[31/47] drm/i915/guc: Reset implementation for new GuC interface

Commit Message

Matthew Brost June 24, 2021, 7:05 a.m. UTC

Reset implementation for new GuC interface. This is the legacy reset
implementation which is called when the i915 owns the engine hang check.
Future patches will offload the engine hang check to GuC but we will
continue to maintain this legacy path as a fallback and this code path
is also required if the GuC dies.

With the new GuC interface it is not possible to reset individual
engines - it is only possible to reset the GPU entirely. This patch
forces an entire chip reset if any engine hangs.

Cc: John Harrison <[e-mail]>
Signed-off-by: Matthew Brost <[e-mail]>
---
 drivers/gpu/drm/i915/gt/intel_context.c       |   3 +
 drivers/gpu/drm/i915/gt/intel_context_types.h |   7 +
 drivers/gpu/drm/i915/gt/intel_engine_types.h  |   6 +
 .../drm/i915/gt/intel_execlists_submission.c  |  40 ++
 drivers/gpu/drm/i915/gt/intel_gt_pm.c         |   6 +-
 drivers/gpu/drm/i915/gt/intel_reset.c         |  18 +-
 .../gpu/drm/i915/gt/intel_ring_submission.c   |  22 +
 drivers/gpu/drm/i915/gt/mock_engine.c         |  31 +
 drivers/gpu/drm/i915/gt/uc/intel_guc.c        |  13 -
 drivers/gpu/drm/i915/gt/uc/intel_guc.h        |   8 +-
 .../gpu/drm/i915/gt/uc/intel_guc_submission.c | 581 ++++++++++++++----
 drivers/gpu/drm/i915/gt/uc/intel_uc.c         |  39 +-
 drivers/gpu/drm/i915/gt/uc/intel_uc.h         |   3 +
 drivers/gpu/drm/i915/i915_request.c           |  41 +-
 drivers/gpu/drm/i915/i915_request.h           |   2 +
 15 files changed, 649 insertions(+), 171 deletions(-)

Comments

John Harrison July 12, 2021, 7:58 p.m. UTC | #1

On 6/24/2021 00:05, Matthew Brost wrote:
> Reset implementation for new GuC interface. This is the legacy reset
> implementation which is called when the i915 owns the engine hang check.
> Future patches will offload the engine hang check to GuC but we will
> continue to maintain this legacy path as a fallback and this code path
> is also required if the GuC dies.
>
> With the new GuC interface it is not possible to reset individual
> engines - it is only possible to reset the GPU entirely. This patch
> forces an entire chip reset if any engine hangs.
There seems to be quite a lot more code being changed in the patch than 
is described above. Sure, it's all in order to support resets but there 
is a lot happening to request/context management, support for GuC 
submission enable/disable, etc. It feels like this patch really should 
be split into a couple of prep patches followed by the actual reset 
support. Plus see couple of minor comments below.

> Cc: John Harrison <[e-mail]>
> Signed-off-by: Matthew Brost <[e-mail]>
> ---
>   drivers/gpu/drm/i915/gt/intel_context.c       |   3 +
>   drivers/gpu/drm/i915/gt/intel_context_types.h |   7 +
>   drivers/gpu/drm/i915/gt/intel_engine_types.h  |   6 +
>   .../drm/i915/gt/intel_execlists_submission.c  |  40 ++
>   drivers/gpu/drm/i915/gt/intel_gt_pm.c         |   6 +-
>   drivers/gpu/drm/i915/gt/intel_reset.c         |  18 +-
>   .../gpu/drm/i915/gt/intel_ring_submission.c   |  22 +
>   drivers/gpu/drm/i915/gt/mock_engine.c         |  31 +
>   drivers/gpu/drm/i915/gt/uc/intel_guc.c        |  13 -
>   drivers/gpu/drm/i915/gt/uc/intel_guc.h        |   8 +-
>   .../gpu/drm/i915/gt/uc/intel_guc_submission.c | 581 ++++++++++++++----
>   drivers/gpu/drm/i915/gt/uc/intel_uc.c         |  39 +-
>   drivers/gpu/drm/i915/gt/uc/intel_uc.h         |   3 +
>   drivers/gpu/drm/i915/i915_request.c           |  41 +-
>   drivers/gpu/drm/i915/i915_request.h           |   2 +
>   15 files changed, 649 insertions(+), 171 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gt/intel_context.c b/drivers/gpu/drm/i915/gt/intel_context.c
> index b24a1b7a3f88..2f01437056a8 100644
> --- a/drivers/gpu/drm/i915/gt/intel_context.c
> +++ b/drivers/gpu/drm/i915/gt/intel_context.c
> @@ -392,6 +392,9 @@ intel_context_init(struct intel_context *ce, struct intel_engine_cs *engine)
>   	spin_lock_init(&ce->guc_state.lock);
>   	INIT_LIST_HEAD(&ce->guc_state.fences);
>   
> +	spin_lock_init(&ce->guc_active.lock);
> +	INIT_LIST_HEAD(&ce->guc_active.requests);
> +
>   	ce->guc_id = GUC_INVALID_LRC_ID;
>   	INIT_LIST_HEAD(&ce->guc_id_link);
>   
> diff --git a/drivers/gpu/drm/i915/gt/intel_context_types.h b/drivers/gpu/drm/i915/gt/intel_context_types.h
> index 6945963a31ba..b63c8cf7823b 100644
> --- a/drivers/gpu/drm/i915/gt/intel_context_types.h
> +++ b/drivers/gpu/drm/i915/gt/intel_context_types.h
> @@ -165,6 +165,13 @@ struct intel_context {
>   		struct list_head fences;
>   	} guc_state;
>   
> +	struct {
> +		/** lock: protects everything in guc_active */
> +		spinlock_t lock;
> +		/** requests: active requests on this context */
> +		struct list_head requests;
> +	} guc_active;
> +
>   	/* GuC scheduling state that does not require a lock. */
>   	atomic_t guc_sched_state_no_lock;
>   
> diff --git a/drivers/gpu/drm/i915/gt/intel_engine_types.h b/drivers/gpu/drm/i915/gt/intel_engine_types.h
> index e7cb6a06db9d..f9d264c008e8 100644
> --- a/drivers/gpu/drm/i915/gt/intel_engine_types.h
> +++ b/drivers/gpu/drm/i915/gt/intel_engine_types.h
> @@ -426,6 +426,12 @@ struct intel_engine_cs {
>   
>   	void		(*release)(struct intel_engine_cs *engine);
>   
> +	/*
> +	 * Add / remove request from engine active tracking
> +	 */
> +	void		(*add_active_request)(struct i915_request *rq);
> +	void		(*remove_active_request)(struct i915_request *rq);
> +
>   	struct intel_engine_execlists execlists;
>   
>   	/*
> diff --git a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
> index c10ea6080752..c301a2d088b1 100644
> --- a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
> +++ b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
> @@ -3118,6 +3118,42 @@ static void execlists_park(struct intel_engine_cs *engine)
>   	cancel_timer(&engine->execlists.preempt);
>   }
>   
> +static void add_to_engine(struct i915_request *rq)
> +{
> +	lockdep_assert_held(&rq->engine->sched_engine->lock);
> +	list_move_tail(&rq->sched.link, &rq->engine->sched_engine->requests);
> +}
> +
> +static void remove_from_engine(struct i915_request *rq)
> +{
> +	struct intel_engine_cs *engine, *locked;
> +
> +	/*
> +	 * Virtual engines complicate acquiring the engine timeline lock,
> +	 * as their rq->engine pointer is not stable until under that
> +	 * engine lock. The simple ploy we use is to take the lock then
> +	 * check that the rq still belongs to the newly locked engine.
> +	 */
> +	locked = READ_ONCE(rq->engine);
> +	spin_lock_irq(&locked->sched_engine->lock);
> +	while (unlikely(locked != (engine = READ_ONCE(rq->engine)))) {
> +		spin_unlock(&locked->sched_engine->lock);
> +		spin_lock(&engine->sched_engine->lock);
> +		locked = engine;
> +	}
> +	list_del_init(&rq->sched.link);
> +
> +	clear_bit(I915_FENCE_FLAG_PQUEUE, &rq->fence.flags);
> +	clear_bit(I915_FENCE_FLAG_HOLD, &rq->fence.flags);
> +
> +	/* Prevent further __await_execution() registering a cb, then flush */
> +	set_bit(I915_FENCE_FLAG_ACTIVE, &rq->fence.flags);
> +
> +	spin_unlock_irq(&locked->sched_engine->lock);
> +
> +	i915_request_notify_execute_cb_imm(rq);
> +}
> +
>   static bool can_preempt(struct intel_engine_cs *engine)
>   {
>   	if (GRAPHICS_VER(engine->i915) > 8)
> @@ -3218,6 +3254,8 @@ logical_ring_default_vfuncs(struct intel_engine_cs *engine)
>   	engine->cops = &execlists_context_ops;
>   	engine->request_alloc = execlists_request_alloc;
>   	engine->bump_serial = execlist_bump_serial;
> +	engine->add_active_request = add_to_engine;
> +	engine->remove_active_request = remove_from_engine;
>   
>   	engine->reset.prepare = execlists_reset_prepare;
>   	engine->reset.rewind = execlists_reset_rewind;
> @@ -3912,6 +3950,8 @@ execlists_create_virtual(struct intel_engine_cs **siblings, unsigned int count)
>   			 "v%dx%d", ve->base.class, count);
>   		ve->base.context_size = sibling->context_size;
>   
> +		ve->base.add_active_request = sibling->add_active_request;
> +		ve->base.remove_active_request = sibling->remove_active_request;
>   		ve->base.emit_bb_start = sibling->emit_bb_start;
>   		ve->base.emit_flush = sibling->emit_flush;
>   		ve->base.emit_init_breadcrumb = sibling->emit_init_breadcrumb;
> diff --git a/drivers/gpu/drm/i915/gt/intel_gt_pm.c b/drivers/gpu/drm/i915/gt/intel_gt_pm.c
> index aef3084e8b16..463a6ae605a0 100644
> --- a/drivers/gpu/drm/i915/gt/intel_gt_pm.c
> +++ b/drivers/gpu/drm/i915/gt/intel_gt_pm.c
> @@ -174,8 +174,6 @@ static void gt_sanitize(struct intel_gt *gt, bool force)
>   	if (intel_gt_is_wedged(gt))
>   		intel_gt_unset_wedged(gt);
>   
> -	intel_uc_sanitize(&gt->uc);
> -
>   	for_each_engine(engine, gt, id)
>   		if (engine->reset.prepare)
>   			engine->reset.prepare(engine);
> @@ -191,6 +189,8 @@ static void gt_sanitize(struct intel_gt *gt, bool force)
>   			__intel_engine_reset(engine, false);
>   	}
>   
> +	intel_uc_reset(&gt->uc, false);
> +
>   	for_each_engine(engine, gt, id)
>   		if (engine->reset.finish)
>   			engine->reset.finish(engine);
> @@ -243,6 +243,8 @@ int intel_gt_resume(struct intel_gt *gt)
>   		goto err_wedged;
>   	}
>   
> +	intel_uc_reset_finish(&gt->uc);
> +
>   	intel_rps_enable(&gt->rps);
>   	intel_llc_enable(&gt->llc);
>   
> diff --git a/drivers/gpu/drm/i915/gt/intel_reset.c b/drivers/gpu/drm/i915/gt/intel_reset.c
> index 72251638d4ea..2987282dff6d 100644
> --- a/drivers/gpu/drm/i915/gt/intel_reset.c
> +++ b/drivers/gpu/drm/i915/gt/intel_reset.c
> @@ -826,6 +826,8 @@ static int gt_reset(struct intel_gt *gt, intel_engine_mask_t stalled_mask)
>   		__intel_engine_reset(engine, stalled_mask & engine->mask);
>   	local_bh_enable();
>   
> +	intel_uc_reset(&gt->uc, true);
> +
>   	intel_ggtt_restore_fences(gt->ggtt);
>   
>   	return err;
> @@ -850,6 +852,8 @@ static void reset_finish(struct intel_gt *gt, intel_engine_mask_t awake)
>   		if (awake & engine->mask)
>   			intel_engine_pm_put(engine);
>   	}
> +
> +	intel_uc_reset_finish(&gt->uc);
>   }
>   
>   static void nop_submit_request(struct i915_request *request)
> @@ -903,6 +907,7 @@ static void __intel_gt_set_wedged(struct intel_gt *gt)
>   	for_each_engine(engine, gt, id)
>   		if (engine->reset.cancel)
>   			engine->reset.cancel(engine);
> +	intel_uc_cancel_requests(&gt->uc);
>   	local_bh_enable();
>   
>   	reset_finish(gt, awake);
> @@ -1191,6 +1196,9 @@ int __intel_engine_reset_bh(struct intel_engine_cs *engine, const char *msg)
>   	ENGINE_TRACE(engine, "flags=%lx\n", gt->reset.flags);
>   	GEM_BUG_ON(!test_bit(I915_RESET_ENGINE + engine->id, &gt->reset.flags));
>   
> +	if (intel_engine_uses_guc(engine))
> +		return -ENODEV;
> +
>   	if (!intel_engine_pm_get_if_awake(engine))
>   		return 0;
>   
> @@ -1201,13 +1209,10 @@ int __intel_engine_reset_bh(struct intel_engine_cs *engine, const char *msg)
>   			   "Resetting %s for %s\n", engine->name, msg);
>   	atomic_inc(&engine->i915->gpu_error.reset_engine_count[engine->uabi_class]);
>   
> -	if (intel_engine_uses_guc(engine))
> -		ret = intel_guc_reset_engine(&engine->gt->uc.guc, engine);
> -	else
> -		ret = intel_gt_reset_engine(engine);
> +	ret = intel_gt_reset_engine(engine);
>   	if (ret) {
>   		/* If we fail here, we expect to fallback to a global reset */
> -		ENGINE_TRACE(engine, "Failed to reset, err: %d\n", ret);
> +		ENGINE_TRACE(engine, "Failed to reset %s, err: %d\n", engine->name, ret);
>   		goto out;
>   	}
>   
> @@ -1341,7 +1346,8 @@ void intel_gt_handle_error(struct intel_gt *gt,
>   	 * Try engine reset when available. We fall back to full reset if
>   	 * single reset fails.
>   	 */
> -	if (intel_has_reset_engine(gt) && !intel_gt_is_wedged(gt)) {
> +	if (!intel_uc_uses_guc_submission(&gt->uc) &&
> +	    intel_has_reset_engine(gt) && !intel_gt_is_wedged(gt)) {
>   		local_bh_disable();
>   		for_each_engine_masked(engine, gt, engine_mask, tmp) {
>   			BUILD_BUG_ON(I915_RESET_MODESET >= I915_RESET_ENGINE);
> diff --git a/drivers/gpu/drm/i915/gt/intel_ring_submission.c b/drivers/gpu/drm/i915/gt/intel_ring_submission.c
> index e1506b280df1..99dcdc8fba12 100644
> --- a/drivers/gpu/drm/i915/gt/intel_ring_submission.c
> +++ b/drivers/gpu/drm/i915/gt/intel_ring_submission.c
> @@ -1049,6 +1049,25 @@ static void ring_bump_serial(struct intel_engine_cs *engine)
>   	engine->serial++;
>   }
>   
> +static void add_to_engine(struct i915_request *rq)
> +{
> +	lockdep_assert_held(&rq->engine->sched_engine->lock);
> +	list_move_tail(&rq->sched.link, &rq->engine->sched_engine->requests);
> +}
> +
> +static void remove_from_engine(struct i915_request *rq)
> +{
> +	spin_lock_irq(&rq->engine->sched_engine->lock);
> +	list_del_init(&rq->sched.link);
> +
> +	/* Prevent further __await_execution() registering a cb, then flush */
> +	set_bit(I915_FENCE_FLAG_ACTIVE, &rq->fence.flags);
> +
> +	spin_unlock_irq(&rq->engine->sched_engine->lock);
> +
> +	i915_request_notify_execute_cb_imm(rq);
> +}
> +
>   static void setup_common(struct intel_engine_cs *engine)
>   {
>   	struct drm_i915_private *i915 = engine->i915;
> @@ -1066,6 +1085,9 @@ static void setup_common(struct intel_engine_cs *engine)
>   	engine->reset.cancel = reset_cancel;
>   	engine->reset.finish = reset_finish;
>   
> +	engine->add_active_request = add_to_engine;
> +	engine->remove_active_request = remove_from_engine;
> +
>   	engine->cops = &ring_context_ops;
>   	engine->request_alloc = ring_request_alloc;
>   	engine->bump_serial = ring_bump_serial;
> diff --git a/drivers/gpu/drm/i915/gt/mock_engine.c b/drivers/gpu/drm/i915/gt/mock_engine.c
> index fc5a65ab1937..c12ff3a75ce6 100644
> --- a/drivers/gpu/drm/i915/gt/mock_engine.c
> +++ b/drivers/gpu/drm/i915/gt/mock_engine.c
> @@ -235,6 +235,35 @@ static void mock_submit_request(struct i915_request *request)
>   	spin_unlock_irqrestore(&engine->hw_lock, flags);
>   }
>   
> +static void mock_add_to_engine(struct i915_request *rq)
> +{
> +	lockdep_assert_held(&rq->engine->sched_engine->lock);
> +	list_move_tail(&rq->sched.link, &rq->engine->sched_engine->requests);
> +}
> +
> +static void mock_remove_from_engine(struct i915_request *rq)
> +{
> +	struct intel_engine_cs *engine, *locked;
> +
> +	/*
> +	 * Virtual engines complicate acquiring the engine timeline lock,
> +	 * as their rq->engine pointer is not stable until under that
> +	 * engine lock. The simple ploy we use is to take the lock then
> +	 * check that the rq still belongs to the newly locked engine.
> +	 */
> +
> +	locked = READ_ONCE(rq->engine);
> +	spin_lock_irq(&locked->sched_engine->lock);
> +	while (unlikely(locked != (engine = READ_ONCE(rq->engine)))) {
> +		spin_unlock(&locked->sched_engine->lock);
> +		spin_lock(&engine->sched_engine->lock);
> +		locked = engine;
> +	}
> +	list_del_init(&rq->sched.link);
> +	spin_unlock_irq(&locked->sched_engine->lock);
> +}
> +
> +
>   static void mock_reset_prepare(struct intel_engine_cs *engine)
>   {
>   }
> @@ -327,6 +356,8 @@ struct intel_engine_cs *mock_engine(struct drm_i915_private *i915,
>   	engine->base.emit_flush = mock_emit_flush;
>   	engine->base.emit_fini_breadcrumb = mock_emit_breadcrumb;
>   	engine->base.submit_request = mock_submit_request;
> +	engine->base.add_active_request = mock_add_to_engine;
> +	engine->base.remove_active_request = mock_remove_from_engine;
>   
>   	engine->base.reset.prepare = mock_reset_prepare;
>   	engine->base.reset.rewind = mock_reset_rewind;
> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc.c b/drivers/gpu/drm/i915/gt/uc/intel_guc.c
> index 6661dcb02239..9b09395b998f 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc.c
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc.c
> @@ -572,19 +572,6 @@ int intel_guc_suspend(struct intel_guc *guc)
>   	return 0;
>   }
>   
> -/**
> - * intel_guc_reset_engine() - ask GuC to reset an engine
> - * @guc:	intel_guc structure
> - * @engine:	engine to be reset
> - */
> -int intel_guc_reset_engine(struct intel_guc *guc,
> -			   struct intel_engine_cs *engine)
> -{
> -	/* XXX: to be implemented with submission interface rework */
> -
> -	return -ENODEV;
> -}
> -
>   /**
>    * intel_guc_resume() - notify GuC resuming from suspend state
>    * @guc:	the guc
> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc.h b/drivers/gpu/drm/i915/gt/uc/intel_guc.h
> index 22eb1e9cca41..40c9868762d7 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc.h
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc.h
> @@ -242,14 +242,16 @@ static inline void intel_guc_disable_msg(struct intel_guc *guc, u32 mask)
>   
>   int intel_guc_wait_for_idle(struct intel_guc *guc, long timeout);
>   
> -int intel_guc_reset_engine(struct intel_guc *guc,
> -			   struct intel_engine_cs *engine);
> -
>   int intel_guc_deregister_done_process_msg(struct intel_guc *guc,
>   					  const u32 *msg, u32 len);
>   int intel_guc_sched_done_process_msg(struct intel_guc *guc,
>   				     const u32 *msg, u32 len);
>   
> +void intel_guc_submission_reset_prepare(struct intel_guc *guc);
> +void intel_guc_submission_reset(struct intel_guc *guc, bool stalled);
> +void intel_guc_submission_reset_finish(struct intel_guc *guc);
> +void intel_guc_submission_cancel_requests(struct intel_guc *guc);
> +
>   void intel_guc_load_status(struct intel_guc *guc, struct drm_printer *p);
>   
>   #endif
> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> index 83058df5ba01..b8c894ad8caf 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> @@ -141,7 +141,7 @@ context_wait_for_deregister_to_register(struct intel_context *ce)
>   static inline void
>   set_context_wait_for_deregister_to_register(struct intel_context *ce)
>   {
> -	/* Only should be called from guc_lrc_desc_pin() */
> +	/* Only should be called from guc_lrc_desc_pin() without lock */
>   	ce->guc_state.sched_state |=
>   		SCHED_STATE_WAIT_FOR_DEREGISTER_TO_REGISTER;
>   }
> @@ -241,15 +241,31 @@ static int guc_lrc_desc_pool_create(struct intel_guc *guc)
>   
>   static void guc_lrc_desc_pool_destroy(struct intel_guc *guc)
>   {
> +	guc->lrc_desc_pool_vaddr = NULL;
>   	i915_vma_unpin_and_release(&guc->lrc_desc_pool, I915_VMA_RELEASE_MAP);
>   }
>   
> +static inline bool guc_submission_initialized(struct intel_guc *guc)
> +{
> +	return guc->lrc_desc_pool_vaddr != NULL;
> +}
> +
>   static inline void reset_lrc_desc(struct intel_guc *guc, u32 id)
>   {
> -	struct guc_lrc_desc *desc = __get_lrc_desc(guc, id);
> +	if (likely(guc_submission_initialized(guc))) {
> +		struct guc_lrc_desc *desc = __get_lrc_desc(guc, id);
> +		unsigned long flags;
>   
> -	memset(desc, 0, sizeof(*desc));
> -	xa_erase_irq(&guc->context_lookup, id);
> +		memset(desc, 0, sizeof(*desc));
> +
> +		/*
> +		 * xarray API doesn't have xa_erase_irqsave wrapper, so calling
> +		 * the lower level functions directly.
> +		 */
> +		xa_lock_irqsave(&guc->context_lookup, flags);
> +		__xa_erase(&guc->context_lookup, id);
> +		xa_unlock_irqrestore(&guc->context_lookup, flags);
> +	}
>   }
>   
>   static inline bool lrc_desc_registered(struct intel_guc *guc, u32 id)
> @@ -260,7 +276,15 @@ static inline bool lrc_desc_registered(struct intel_guc *guc, u32 id)
>   static inline void set_lrc_desc_registered(struct intel_guc *guc, u32 id,
>   					   struct intel_context *ce)
>   {
> -	xa_store_irq(&guc->context_lookup, id, ce, GFP_ATOMIC);
> +	unsigned long flags;
> +
> +	/*
> +	 * xarray API doesn't have xa_save_irqsave wrapper, so calling the
> +	 * lower level functions directly.
> +	 */
> +	xa_lock_irqsave(&guc->context_lookup, flags);
> +	__xa_store(&guc->context_lookup, id, ce, GFP_ATOMIC);
> +	xa_unlock_irqrestore(&guc->context_lookup, flags);
>   }
>   
>   static int guc_submission_busy_loop(struct intel_guc* guc,
> @@ -331,6 +355,8 @@ int intel_guc_wait_for_idle(struct intel_guc *guc, long timeout)
>   					interruptible, timeout);
>   }
>   
> +static int guc_lrc_desc_pin(struct intel_context *ce, bool loop);
> +
>   static int guc_add_request(struct intel_guc *guc, struct i915_request *rq)
>   {
>   	int err;
> @@ -338,11 +364,22 @@ static int guc_add_request(struct intel_guc *guc, struct i915_request *rq)
>   	u32 action[3];
>   	int len = 0;
>   	u32 g2h_len_dw = 0;
> -	bool enabled = context_enabled(ce);
> +	bool enabled;
>   
>   	GEM_BUG_ON(!atomic_read(&ce->guc_id_ref));
>   	GEM_BUG_ON(context_guc_id_invalid(ce));
>   
> +	/*
> +	 * Corner case where the GuC firmware was blown away and reloaded while
> +	 * this context was pinned.
> +	 */
> +	if (unlikely(!lrc_desc_registered(guc, ce->guc_id))) {
> +		err = guc_lrc_desc_pin(ce, false);
> +		if (unlikely(err))
> +			goto out;
> +	}
> +	enabled = context_enabled(ce);
> +
>   	if (!enabled) {
>   		action[len++] = INTEL_GUC_ACTION_SCHED_CONTEXT_MODE_SET;
>   		action[len++] = ce->guc_id;
> @@ -365,6 +402,7 @@ static int guc_add_request(struct intel_guc *guc, struct i915_request *rq)
>   		intel_context_put(ce);
>   	}
>   
> +out:
>   	return err;
>   }
>   
> @@ -419,15 +457,10 @@ static int guc_dequeue_one_context(struct intel_guc *guc)
>   	if (submit) {
>   		guc_set_lrc_tail(last);
>   resubmit:
> -		/*
> -		 * We only check for -EBUSY here even though it is possible for
> -		 * -EDEADLK to be returned. If -EDEADLK is returned, the GuC has
> -		 * died and a full GPU needs to be done. The hangcheck will
> -		 * eventually detect that the GuC has died and trigger this
> -		 * reset so no need to handle -EDEADLK here.
> -		 */
>   		ret = guc_add_request(guc, last);
> -		if (ret == -EBUSY) {
> +		if (unlikely(ret == -EIO))
> +			goto deadlk;
> +		else if (ret == -EBUSY) {
>   			tasklet_schedule(&sched_engine->tasklet);
>   			guc->stalled_request = last;
>   			return false;
> @@ -437,6 +470,11 @@ static int guc_dequeue_one_context(struct intel_guc *guc)
>   
>   	guc->stalled_request = NULL;
>   	return submit;
> +
> +deadlk:
> +	sched_engine->tasklet.callback = NULL;
> +	tasklet_disable_nosync(&sched_engine->tasklet);
> +	return false;
>   }
>   
>   static void guc_submission_tasklet(struct tasklet_struct *t)
> @@ -463,27 +501,165 @@ static void cs_irq_handler(struct intel_engine_cs *engine, u16 iir)
>   		intel_engine_signal_breadcrumbs(engine);
>   }
>   
> -static void guc_reset_prepare(struct intel_engine_cs *engine)
> +static void __guc_context_destroy(struct intel_context *ce);
> +static void release_guc_id(struct intel_guc *guc, struct intel_context *ce);
> +static void guc_signal_context_fence(struct intel_context *ce);
> +
> +static void scrub_guc_desc_for_outstanding_g2h(struct intel_guc *guc)
> +{
> +	struct intel_context *ce;
> +	unsigned long index, flags;
> +	bool pending_disable, pending_enable, deregister, destroyed;
> +
> +	xa_for_each(&guc->context_lookup, index, ce) {
> +		/* Flush context */
> +		spin_lock_irqsave(&ce->guc_state.lock, flags);
> +		spin_unlock_irqrestore(&ce->guc_state.lock, flags);
> +
> +		/*
> +		 * Once we are at this point submission_disabled() is guaranteed
> +		 * to visible to all callers who set the below flags (see above
to be visible

> +		 * flush and flushes in reset_prepare). If submission_disabled()
> +		 * is set, the caller shouldn't set these flags.
> +		 */
> +
> +		destroyed = context_destroyed(ce);
> +		pending_enable = context_pending_enable(ce);
> +		pending_disable = context_pending_disable(ce);
> +		deregister = context_wait_for_deregister_to_register(ce);
> +		init_sched_state(ce);
> +
> +		if (pending_enable || destroyed || deregister) {
> +			atomic_dec(&guc->outstanding_submission_g2h);
> +			if (deregister)
> +				guc_signal_context_fence(ce);
> +			if (destroyed) {
> +				release_guc_id(guc, ce);
> +				__guc_context_destroy(ce);
> +			}
> +			if (pending_enable|| deregister)
> +				intel_context_put(ce);
> +		}
> +
> +		/* Not mutualy exclusive with above if statement. */
> +		if (pending_disable) {
> +			guc_signal_context_fence(ce);
> +			intel_context_sched_disable_unpin(ce);
> +			atomic_dec(&guc->outstanding_submission_g2h);
> +			intel_context_put(ce);
> +		}
> +	}
> +}
> +
> +static inline bool
> +submission_disabled(struct intel_guc *guc)
> +{
> +	struct i915_sched_engine * const sched_engine = guc->sched_engine;
> +
> +	return unlikely(!__tasklet_is_enabled(&sched_engine->tasklet));
> +}
> +
> +static void disable_submission(struct intel_guc *guc)
> +{
> +	struct i915_sched_engine * const sched_engine = guc->sched_engine;
> +
> +	if (__tasklet_is_enabled(&sched_engine->tasklet)) {
> +		GEM_BUG_ON(!guc->ct.enabled);
> +		__tasklet_disable_sync_once(&sched_engine->tasklet);
> +		sched_engine->tasklet.callback = NULL;
> +	}
> +}
> +
> +static void enable_submission(struct intel_guc *guc)
> +{
> +	struct i915_sched_engine * const sched_engine = guc->sched_engine;
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&guc->sched_engine->lock, flags);
> +	sched_engine->tasklet.callback = guc_submission_tasklet;
> +	wmb();
> +	if (!__tasklet_is_enabled(&sched_engine->tasklet) &&
> +	    __tasklet_enable(&sched_engine->tasklet)) {
> +		GEM_BUG_ON(!guc->ct.enabled);
> +
> +		/* And kick in case we missed a new request submission. */
> +		tasklet_hi_schedule(&sched_engine->tasklet);
> +	}
> +	spin_unlock_irqrestore(&guc->sched_engine->lock, flags);
> +}
> +
> +static void guc_flush_submissions(struct intel_guc *guc)
>   {
> -	ENGINE_TRACE(engine, "\n");
> +	struct i915_sched_engine * const sched_engine = guc->sched_engine;
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&sched_engine->lock, flags);
> +	spin_unlock_irqrestore(&sched_engine->lock, flags);
> +}
> +
> +void intel_guc_submission_reset_prepare(struct intel_guc *guc)
> +{
> +	int i;
> +
> +	if (unlikely(!guc_submission_initialized(guc)))
> +		/* Reset called during driver load? GuC not yet initialised! */
> +		return;
Ew. Multi-line if without braces just looks broken even if one line is 
just a comment.

> +
> +	disable_submission(guc);
> +	guc->interrupts.disable(guc);
> +
> +	/* Flush IRQ handler */
> +	spin_lock_irq(&guc_to_gt(guc)->irq_lock);
> +	spin_unlock_irq(&guc_to_gt(guc)->irq_lock);
> +
> +	guc_flush_submissions(guc);
>   
>   	/*
> -	 * Prevent request submission to the hardware until we have
> -	 * completed the reset in i915_gem_reset_finish(). If a request
> -	 * is completed by one engine, it may then queue a request
> -	 * to a second via its execlists->tasklet *just* as we are
> -	 * calling engine->init_hw() and also writing the ELSP.
> -	 * Turning off the execlists->tasklet until the reset is over
> -	 * prevents the race.
> -	 */
> -	__tasklet_disable_sync_once(&engine->sched_engine->tasklet);
> +	 * Handle any outstanding G2Hs before reset. Call IRQ handler directly
> +	 * each pass as interrupt have been disabled. We always scrub for
> +	 * outstanding G2H as it is possible for outstanding_submission_g2h to
> +	 * be incremented after the context state update.
> + 	 */
> +	for (i = 0; i < 4 && atomic_read(&guc->outstanding_submission_g2h); ++i) {
> +		intel_guc_to_host_event_handler(guc);
> +#define wait_for_reset(guc, wait_var) \
> +		guc_wait_for_pending_msg(guc, wait_var, false, (HZ / 20))
> +		do {
> +			wait_for_reset(guc, &guc->outstanding_submission_g2h);
> +		} while (!list_empty(&guc->ct.requests.incoming));
> +	}
> +	scrub_guc_desc_for_outstanding_g2h(guc);
>   }
>   
> -static void guc_reset_state(struct intel_context *ce,
> -			    struct intel_engine_cs *engine,
> -			    u32 head,
> -			    bool scrub)
> +static struct intel_engine_cs *
> +guc_virtual_get_sibling(struct intel_engine_cs *ve, unsigned int sibling)
>   {
> +	struct intel_engine_cs *engine;
> +	intel_engine_mask_t tmp, mask = ve->mask;
> +	unsigned int num_siblings = 0;
> +
> +	for_each_engine_masked(engine, ve->gt, mask, tmp)
> +		if (num_siblings++ == sibling)
> +			return engine;
> +
> +	return NULL;
> +}
> +
> +static inline struct intel_engine_cs *
> +__context_to_physical_engine(struct intel_context *ce)
> +{
> +	struct intel_engine_cs *engine = ce->engine;
> +
> +	if (intel_engine_is_virtual(engine))
> +		engine = guc_virtual_get_sibling(engine, 0);
> +
> +	return engine;
> +}
> +
> +static void guc_reset_state(struct intel_context *ce, u32 head, bool scrub)
> +{
> +	struct intel_engine_cs *engine = __context_to_physical_engine(ce);
> +
>   	GEM_BUG_ON(!intel_context_is_pinned(ce));
>   
>   	/*
> @@ -501,42 +677,147 @@ static void guc_reset_state(struct intel_context *ce,
>   	lrc_update_regs(ce, engine, head);
>   }
>   
> -static void guc_reset_rewind(struct intel_engine_cs *engine, bool stalled)
> +static void guc_reset_nop(struct intel_engine_cs *engine)
>   {
> -	struct intel_engine_execlists * const execlists = &engine->execlists;
> -	struct i915_request *rq;
> +}
> +
> +static void guc_rewind_nop(struct intel_engine_cs *engine, bool stalled)
> +{
> +}
> +
> +static void
> +__unwind_incomplete_requests(struct intel_context *ce)
> +{
> +	struct i915_request *rq, *rn;
> +	struct list_head *pl;
> +	int prio = I915_PRIORITY_INVALID;
> +	struct i915_sched_engine * const sched_engine =
> +		ce->engine->sched_engine;
>   	unsigned long flags;
>   
> -	spin_lock_irqsave(&engine->sched_engine->lock, flags);
> +	spin_lock_irqsave(&sched_engine->lock, flags);
> +	spin_lock(&ce->guc_active.lock);
> +	list_for_each_entry_safe(rq, rn,
> +				 &ce->guc_active.requests,
> +				 sched.link) {
> +		if (i915_request_completed(rq))
> +			continue;
> +
> +		list_del_init(&rq->sched.link);
> +		spin_unlock(&ce->guc_active.lock);
> +
> +		__i915_request_unsubmit(rq);
> +
> +		/* Push the request back into the queue for later resubmission. */
> +		GEM_BUG_ON(rq_prio(rq) == I915_PRIORITY_INVALID);
> +		if (rq_prio(rq) != prio) {
> +			prio = rq_prio(rq);
> +			pl = i915_sched_lookup_priolist(sched_engine, prio);
> +		}
> +		GEM_BUG_ON(i915_sched_engine_is_empty(sched_engine));
> +
> +		list_add_tail(&rq->sched.link, pl);
> +		set_bit(I915_FENCE_FLAG_PQUEUE, &rq->fence.flags);
>   
> -	/* Push back any incomplete requests for replay after the reset. */
> -	rq = execlists_unwind_incomplete_requests(execlists);
> -	if (!rq)
> -		goto out_unlock;
> +		spin_lock(&ce->guc_active.lock);
> +	}
> +	spin_unlock(&ce->guc_active.lock);
> +	spin_unlock_irqrestore(&sched_engine->lock, flags);
> +}
> +
> +static struct i915_request *context_find_active_request(struct intel_context *ce)
> +{
> +	struct i915_request *rq, *active = NULL;
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&ce->guc_active.lock, flags);
> +	list_for_each_entry_reverse(rq, &ce->guc_active.requests,
> +				    sched.link) {
> +		if (i915_request_completed(rq))
> +			break;
> +
> +		active = rq;
> +	}
> +	spin_unlock_irqrestore(&ce->guc_active.lock, flags);
> +
> +	return active;
> +}
> +
> +static void __guc_reset_context(struct intel_context *ce, bool stalled)
> +{
> +	struct i915_request *rq;
> +	u32 head;
> +
> +	/*
> +	 * GuC will implicitly mark the context as non-schedulable
> +	 * when it sends the reset notification. Make sure our state
> +	 * reflects this change. The context will be marked enabled
> +	 * on resubmission.
> +	 */
> +	clr_context_enabled(ce);
> +
> +	rq = context_find_active_request(ce);
> +	if (!rq) {
> +		head = ce->ring->tail;
> +		stalled = false;
> +		goto out_replay;
> +	}
>   
>   	if (!i915_request_started(rq))
>   		stalled = false;
>   
> +	GEM_BUG_ON(i915_active_is_idle(&ce->active));
> +	head = intel_ring_wrap(ce->ring, rq->head);
>   	__i915_request_reset(rq, stalled);
> -	guc_reset_state(rq->context, engine, rq->head, stalled);
>   
> -out_unlock:
> -	spin_unlock_irqrestore(&engine->sched_engine->lock, flags);
> +out_replay:
> +	guc_reset_state(ce, head, stalled);
> +	__unwind_incomplete_requests(ce);
>   }
>   
> -static void guc_reset_cancel(struct intel_engine_cs *engine)
> +void intel_guc_submission_reset(struct intel_guc *guc, bool stalled)
> +{
> +	struct intel_context *ce;
> +	unsigned long index;
> +
> +	if (unlikely(!guc_submission_initialized(guc)))
> +		/* Reset called during driver load? GuC not yet initialised! */
> +		return;
And again.

> +
> +	xa_for_each(&guc->context_lookup, index, ce)
> +		if (intel_context_is_pinned(ce))
> +			__guc_reset_context(ce, stalled);
> +
> +	/* GuC is blown away, drop all references to contexts */
> +	xa_destroy(&guc->context_lookup);
> +}
> +
> +static void guc_cancel_context_requests(struct intel_context *ce)
> +{
> +	struct i915_sched_engine *sched_engine = ce_to_guc(ce)->sched_engine;
> +	struct i915_request *rq;
> +	unsigned long flags;
> +
> +	/* Mark all executing requests as skipped. */
> +	spin_lock_irqsave(&sched_engine->lock, flags);
> +	spin_lock(&ce->guc_active.lock);
> +	list_for_each_entry(rq, &ce->guc_active.requests, sched.link)
> +		i915_request_put(i915_request_mark_eio(rq));
> +	spin_unlock(&ce->guc_active.lock);
> +	spin_unlock_irqrestore(&sched_engine->lock, flags);
> +}
> +
> +static void
> +guc_cancel_sched_engine_requests(struct i915_sched_engine *sched_engine)
>   {
> -	struct i915_sched_engine * const sched_engine = engine->sched_engine;
>   	struct i915_request *rq, *rn;
>   	struct rb_node *rb;
>   	unsigned long flags;
>   
>   	/* Can be called during boot if GuC fails to load */
> -	if (!engine->gt)
> +	if (!sched_engine)
>   		return;
>   
> -	ENGINE_TRACE(engine, "\n");
> -
>   	/*
>   	 * Before we call engine->cancel_requests(), we should have exclusive
>   	 * access to the submission state. This is arranged for us by the
> @@ -553,21 +834,16 @@ static void guc_reset_cancel(struct intel_engine_cs *engine)
>   	 */
>   	spin_lock_irqsave(&sched_engine->lock, flags);
>   
> -	/* Mark all executing requests as skipped. */
> -	list_for_each_entry(rq, &sched_engine->requests, sched.link) {
> -		i915_request_set_error_once(rq, -EIO);
> -		i915_request_mark_complete(rq);
> -	}
> -
>   	/* Flush the queued requests to the timeline list (for retiring). */
>   	while ((rb = rb_first_cached(&sched_engine->queue))) {
>   		struct i915_priolist *p = to_priolist(rb);
>   
>   		priolist_for_each_request_consume(rq, rn, p) {
>   			list_del_init(&rq->sched.link);
> +
>   			__i915_request_submit(rq);
> -			dma_fence_set_error(&rq->fence, -EIO);
> -			i915_request_mark_complete(rq);
> +
> +			i915_request_put(i915_request_mark_eio(rq));
>   		}
>   
>   		rb_erase_cached(&p->node, &sched_engine->queue);
> @@ -582,14 +858,38 @@ static void guc_reset_cancel(struct intel_engine_cs *engine)
>   	spin_unlock_irqrestore(&sched_engine->lock, flags);
>   }
>   
> -static void guc_reset_finish(struct intel_engine_cs *engine)
> +void intel_guc_submission_cancel_requests(struct intel_guc *guc)
>   {
> -	if (__tasklet_enable(&engine->sched_engine->tasklet))
> -		/* And kick in case we missed a new request submission. */
> -		tasklet_hi_schedule(&engine->sched_engine->tasklet);
> +	struct intel_context *ce;
> +	unsigned long index;
> +
> +	xa_for_each(&guc->context_lookup, index, ce)
> +		if (intel_context_is_pinned(ce))
> +			guc_cancel_context_requests(ce);
>   
> -	ENGINE_TRACE(engine, "depth->%d\n",
> -		     atomic_read(&engine->sched_engine->tasklet.count));
> +	guc_cancel_sched_engine_requests(guc->sched_engine);
> +
> +	/* GuC is blown away, drop all references to contexts */
> +	xa_destroy(&guc->context_lookup);
This function shares most of the code with 'intel_guc_submission_reset'. 
Can the xa clean be moved to a common helper?

John.

> +}
> +
> +void intel_guc_submission_reset_finish(struct intel_guc *guc)
> +{
> +	/* Reset called during driver load or during wedge? */
> +	if (unlikely(!guc_submission_initialized(guc) ||
> +		     test_bit(I915_WEDGED, &guc_to_gt(guc)->reset.flags)))
> +		return;
> +
> +	/*
> +	 * Technically possible for either of these values to be non-zero here,
> +	 * but very unlikely + harmless. Regardless let's add a warn so we can
> +	 * see in CI if this happens frequently / a precursor to taking down the
> +	 * machine.
> +	 */
> +	GEM_WARN_ON(atomic_read(&guc->outstanding_submission_g2h));
> +	atomic_set(&guc->outstanding_submission_g2h, 0);
> +
> +	enable_submission(guc);
>   }
>   
>   /*
> @@ -656,6 +956,9 @@ static int guc_bypass_tasklet_submit(struct intel_guc *guc,
>   	else
>   		trace_i915_request_guc_submit(rq);
>   
> +	if (unlikely(ret == -EIO))
> +		disable_submission(guc);
> +
>   	return ret;
>   }
>   
> @@ -668,7 +971,8 @@ static void guc_submit_request(struct i915_request *rq)
>   	/* Will be called from irq-context when using foreign fences. */
>   	spin_lock_irqsave(&sched_engine->lock, flags);
>   
> -	if (guc->stalled_request || !i915_sched_engine_is_empty(sched_engine))
> +	if (submission_disabled(guc) || guc->stalled_request ||
> +	    !i915_sched_engine_is_empty(sched_engine))
>   		queue_request(sched_engine, rq, rq_prio(rq));
>   	else if (guc_bypass_tasklet_submit(guc, rq) == -EBUSY)
>   		tasklet_hi_schedule(&sched_engine->tasklet);
> @@ -805,7 +1109,8 @@ static void unpin_guc_id(struct intel_guc *guc, struct intel_context *ce)
>   
>   static int __guc_action_register_context(struct intel_guc *guc,
>   					 u32 guc_id,
> -					 u32 offset)
> +					 u32 offset,
> +					 bool loop)
>   {
>   	u32 action[] = {
>   		INTEL_GUC_ACTION_REGISTER_CONTEXT,
> @@ -813,10 +1118,10 @@ static int __guc_action_register_context(struct intel_guc *guc,
>   		offset,
>   	};
>   
> -	return guc_submission_busy_loop(guc, action, ARRAY_SIZE(action), 0, true);
> +	return guc_submission_busy_loop(guc, action, ARRAY_SIZE(action), 0, loop);
>   }
>   
> -static int register_context(struct intel_context *ce)
> +static int register_context(struct intel_context *ce, bool loop)
>   {
>   	struct intel_guc *guc = ce_to_guc(ce);
>   	u32 offset = intel_guc_ggtt_offset(guc, guc->lrc_desc_pool) +
> @@ -824,11 +1129,12 @@ static int register_context(struct intel_context *ce)
>   
>   	trace_intel_context_register(ce);
>   
> -	return __guc_action_register_context(guc, ce->guc_id, offset);
> +	return __guc_action_register_context(guc, ce->guc_id, offset, loop);
>   }
>   
>   static int __guc_action_deregister_context(struct intel_guc *guc,
> -					   u32 guc_id)
> +					   u32 guc_id,
> +					   bool loop)
>   {
>   	u32 action[] = {
>   		INTEL_GUC_ACTION_DEREGISTER_CONTEXT,
> @@ -836,16 +1142,16 @@ static int __guc_action_deregister_context(struct intel_guc *guc,
>   	};
>   
>   	return guc_submission_busy_loop(guc, action, ARRAY_SIZE(action),
> -					G2H_LEN_DW_DEREGISTER_CONTEXT, true);
> +					G2H_LEN_DW_DEREGISTER_CONTEXT, loop);
>   }
>   
> -static int deregister_context(struct intel_context *ce, u32 guc_id)
> +static int deregister_context(struct intel_context *ce, u32 guc_id, bool loop)
>   {
>   	struct intel_guc *guc = ce_to_guc(ce);
>   
>   	trace_intel_context_deregister(ce);
>   
> -	return __guc_action_deregister_context(guc, guc_id);
> +	return __guc_action_deregister_context(guc, guc_id, loop);
>   }
>   
>   static intel_engine_mask_t adjust_engine_mask(u8 class, intel_engine_mask_t mask)
> @@ -874,7 +1180,7 @@ static void guc_context_policy_init(struct intel_engine_cs *engine,
>   	desc->preemption_timeout = CONTEXT_POLICY_DEFAULT_PREEMPTION_TIME_US;
>   }
>   
> -static int guc_lrc_desc_pin(struct intel_context *ce)
> +static int guc_lrc_desc_pin(struct intel_context *ce, bool loop)
>   {
>   	struct intel_runtime_pm *runtime_pm =
>   		&ce->engine->gt->i915->runtime_pm;
> @@ -920,18 +1226,44 @@ static int guc_lrc_desc_pin(struct intel_context *ce)
>   	 */
>   	if (context_registered) {
>   		trace_intel_context_steal_guc_id(ce);
> -		set_context_wait_for_deregister_to_register(ce);
> -		intel_context_get(ce);
> +		if (!loop) {
> +			set_context_wait_for_deregister_to_register(ce);
> +			intel_context_get(ce);
> +		} else {
> +			bool disabled;
> +			unsigned long flags;
> +
> +			/* Seal race with Reset */
> +			spin_lock_irqsave(&ce->guc_state.lock, flags);
> +			disabled = submission_disabled(guc);
> +			if (likely(!disabled)) {
> +				set_context_wait_for_deregister_to_register(ce);
> +				intel_context_get(ce);
> +			}
> +			spin_unlock_irqrestore(&ce->guc_state.lock, flags);
> +			if (unlikely(disabled)) {
> +				reset_lrc_desc(guc, desc_idx);
> +				return 0;	/* Will get registered later */
> +			}
> +		}
>   
>   		/*
>   		 * If stealing the guc_id, this ce has the same guc_id as the
>   		 * context whos guc_id was stole.
>   		 */
>   		with_intel_runtime_pm(runtime_pm, wakeref)
> -			ret = deregister_context(ce, ce->guc_id);
> +			ret = deregister_context(ce, ce->guc_id, loop);
> +		if (unlikely(ret == -EBUSY)) {
> +			clr_context_wait_for_deregister_to_register(ce);
> +			intel_context_put(ce);
> +		}
>   	} else {
>   		with_intel_runtime_pm(runtime_pm, wakeref)
> -			ret = register_context(ce);
> +			ret = register_context(ce, loop);
> +		if (unlikely(ret == -EBUSY))
> +			reset_lrc_desc(guc, desc_idx);
> +		else if (unlikely(ret == -ENODEV))
> +			ret = 0;	/* Will get registered later */
>   	}
>   
>   	return ret;
> @@ -994,7 +1326,6 @@ static void __guc_context_sched_disable(struct intel_guc *guc,
>   	GEM_BUG_ON(guc_id == GUC_INVALID_LRC_ID);
>   
>   	trace_intel_context_sched_disable(ce);
> -	intel_context_get(ce);
>   
>   	guc_submission_busy_loop(guc, action, ARRAY_SIZE(action),
>   				 G2H_LEN_DW_SCHED_CONTEXT_MODE_SET, true);
> @@ -1004,6 +1335,7 @@ static u16 prep_context_pending_disable(struct intel_context *ce)
>   {
>   	set_context_pending_disable(ce);
>   	clr_context_enabled(ce);
> +	intel_context_get(ce);
>   
>   	return ce->guc_id;
>   }
> @@ -1016,7 +1348,7 @@ static void guc_context_sched_disable(struct intel_context *ce)
>   	u16 guc_id;
>   	intel_wakeref_t wakeref;
>   
> -	if (context_guc_id_invalid(ce) ||
> +	if (submission_disabled(guc) || context_guc_id_invalid(ce) ||
>   	    !lrc_desc_registered(guc, ce->guc_id)) {
>   		clr_context_enabled(ce);
>   		goto unpin;
> @@ -1034,6 +1366,7 @@ static void guc_context_sched_disable(struct intel_context *ce)
>   	 * request doesn't slip through the 'context_pending_disable' fence.
>   	 */
>   	if (unlikely(atomic_add_unless(&ce->pin_count, -2, 2))) {
> +		spin_unlock_irqrestore(&ce->guc_state.lock, flags);
>   		return;
>   	}
>   	guc_id = prep_context_pending_disable(ce);
> @@ -1050,19 +1383,13 @@ static void guc_context_sched_disable(struct intel_context *ce)
>   
>   static inline void guc_lrc_desc_unpin(struct intel_context *ce)
>   {
> -	struct intel_engine_cs *engine = ce->engine;
> -	struct intel_guc *guc = &engine->gt->uc.guc;
> -	unsigned long flags;
> +	struct intel_guc *guc = ce_to_guc(ce);
>   
>   	GEM_BUG_ON(!lrc_desc_registered(guc, ce->guc_id));
>   	GEM_BUG_ON(ce != __get_context(guc, ce->guc_id));
>   	GEM_BUG_ON(context_enabled(ce));
>   
> -	spin_lock_irqsave(&ce->guc_state.lock, flags);
> -	set_context_destroyed(ce);
> -	spin_unlock_irqrestore(&ce->guc_state.lock, flags);
> -
> -	deregister_context(ce, ce->guc_id);
> +	deregister_context(ce, ce->guc_id, true);
>   }
>   
>   static void __guc_context_destroy(struct intel_context *ce)
> @@ -1090,13 +1417,15 @@ static void guc_context_destroy(struct kref *kref)
>   	struct intel_guc *guc = &ce->engine->gt->uc.guc;
>   	intel_wakeref_t wakeref;
>   	unsigned long flags;
> +	bool disabled;
>   
>   	/*
>   	 * If the guc_id is invalid this context has been stolen and we can free
>   	 * it immediately. Also can be freed immediately if the context is not
>   	 * registered with the GuC.
>   	 */
> -	if (context_guc_id_invalid(ce) ||
> +	if (submission_disabled(guc) ||
> +	    context_guc_id_invalid(ce) ||
>   	    !lrc_desc_registered(guc, ce->guc_id)) {
>   		release_guc_id(guc, ce);
>   		__guc_context_destroy(ce);
> @@ -1123,6 +1452,18 @@ static void guc_context_destroy(struct kref *kref)
>   		list_del_init(&ce->guc_id_link);
>   	spin_unlock_irqrestore(&guc->contexts_lock, flags);
>   
> +	/* Seal race with Reset */
> +	spin_lock_irqsave(&ce->guc_state.lock, flags);
> +	disabled = submission_disabled(guc);
> +	if (likely(!disabled))
> +		set_context_destroyed(ce);
> +	spin_unlock_irqrestore(&ce->guc_state.lock, flags);
> +	if (unlikely(disabled)) {
> +		release_guc_id(guc, ce);
> +		__guc_context_destroy(ce);
> +		return;
> +	}
> +
>   	/*
>   	 * We defer GuC context deregistration until the context is destroyed
>   	 * in order to save on CTBs. With this optimization ideally we only need
> @@ -1145,6 +1486,33 @@ static int guc_context_alloc(struct intel_context *ce)
>   	return lrc_alloc(ce, ce->engine);
>   }
>   
> +static void add_to_context(struct i915_request *rq)
> +{
> +	struct intel_context *ce = rq->context;
> +
> +	spin_lock(&ce->guc_active.lock);
> +	list_move_tail(&rq->sched.link, &ce->guc_active.requests);
> +	spin_unlock(&ce->guc_active.lock);
> +}
> +
> +static void remove_from_context(struct i915_request *rq)
> +{
> +	struct intel_context *ce = rq->context;
> +
> +	spin_lock_irq(&ce->guc_active.lock);
> +
> +	list_del_init(&rq->sched.link);
> +	clear_bit(I915_FENCE_FLAG_PQUEUE, &rq->fence.flags);
> +
> +	/* Prevent further __await_execution() registering a cb, then flush */
> +	set_bit(I915_FENCE_FLAG_ACTIVE, &rq->fence.flags);
> +
> +	spin_unlock_irq(&ce->guc_active.lock);
> +
> +	atomic_dec(&ce->guc_id_ref);
> +	i915_request_notify_execute_cb_imm(rq);
> +}
> +
>   static const struct intel_context_ops guc_context_ops = {
>   	.alloc = guc_context_alloc,
>   
> @@ -1183,8 +1551,6 @@ static void guc_signal_context_fence(struct intel_context *ce)
>   {
>   	unsigned long flags;
>   
> -	GEM_BUG_ON(!context_wait_for_deregister_to_register(ce));
> -
>   	spin_lock_irqsave(&ce->guc_state.lock, flags);
>   	clr_context_wait_for_deregister_to_register(ce);
>   	__guc_signal_context_fence(ce);
> @@ -1193,8 +1559,9 @@ static void guc_signal_context_fence(struct intel_context *ce)
>   
>   static bool context_needs_register(struct intel_context *ce, bool new_guc_id)
>   {
> -	return new_guc_id || test_bit(CONTEXT_LRCA_DIRTY, &ce->flags) ||
> -		!lrc_desc_registered(ce_to_guc(ce), ce->guc_id);
> +	return (new_guc_id || test_bit(CONTEXT_LRCA_DIRTY, &ce->flags) ||
> +		!lrc_desc_registered(ce_to_guc(ce), ce->guc_id)) &&
> +		!submission_disabled(ce_to_guc(ce));
>   }
>   
>   static int guc_request_alloc(struct i915_request *rq)
> @@ -1252,8 +1619,12 @@ static int guc_request_alloc(struct i915_request *rq)
>   	if (unlikely(ret < 0))
>   		return ret;;
>   	if (context_needs_register(ce, !!ret)) {
> -		ret = guc_lrc_desc_pin(ce);
> +		ret = guc_lrc_desc_pin(ce, true);
>   		if (unlikely(ret)) {	/* unwind */
> +			if (ret == -EIO) {
> +				disable_submission(guc);
> +				goto out;	/* GPU will be reset */
> +			}
>   			atomic_dec(&ce->guc_id_ref);
>   			unpin_guc_id(guc, ce);
>   			return ret;
> @@ -1290,20 +1661,6 @@ static int guc_request_alloc(struct i915_request *rq)
>   	return 0;
>   }
>   
> -static struct intel_engine_cs *
> -guc_virtual_get_sibling(struct intel_engine_cs *ve, unsigned int sibling)
> -{
> -	struct intel_engine_cs *engine;
> -	intel_engine_mask_t tmp, mask = ve->mask;
> -	unsigned int num_siblings = 0;
> -
> -	for_each_engine_masked(engine, ve->gt, mask, tmp)
> -		if (num_siblings++ == sibling)
> -			return engine;
> -
> -	return NULL;
> -}
> -
>   static int guc_virtual_context_pre_pin(struct intel_context *ce,
>   				       struct i915_gem_ww_ctx *ww,
>   				       void **vaddr)
> @@ -1512,7 +1869,7 @@ static inline void guc_kernel_context_pin(struct intel_guc *guc,
>   {
>   	if (context_guc_id_invalid(ce))
>   		pin_guc_id(guc, ce);
> -	guc_lrc_desc_pin(ce);
> +	guc_lrc_desc_pin(ce, true);
>   }
>   
>   static inline void guc_init_lrc_mapping(struct intel_guc *guc)
> @@ -1578,13 +1935,15 @@ static void guc_default_vfuncs(struct intel_engine_cs *engine)
>   	engine->cops = &guc_context_ops;
>   	engine->request_alloc = guc_request_alloc;
>   	engine->bump_serial = guc_bump_serial;
> +	engine->add_active_request = add_to_context;
> +	engine->remove_active_request = remove_from_context;
>   
>   	engine->sched_engine->schedule = i915_schedule;
>   
> -	engine->reset.prepare = guc_reset_prepare;
> -	engine->reset.rewind = guc_reset_rewind;
> -	engine->reset.cancel = guc_reset_cancel;
> -	engine->reset.finish = guc_reset_finish;
> +	engine->reset.prepare = guc_reset_nop;
> +	engine->reset.rewind = guc_rewind_nop;
> +	engine->reset.cancel = guc_reset_nop;
> +	engine->reset.finish = guc_reset_nop;
>   
>   	engine->emit_flush = gen8_emit_flush_xcs;
>   	engine->emit_init_breadcrumb = gen8_emit_init_breadcrumb;
> @@ -1757,7 +2116,7 @@ int intel_guc_deregister_done_process_msg(struct intel_guc *guc,
>   		 * register this context.
>   		 */
>   		with_intel_runtime_pm(runtime_pm, wakeref)
> -			register_context(ce);
> +			register_context(ce, true);
>   		guc_signal_context_fence(ce);
>   		intel_context_put(ce);
>   	} else if (context_destroyed(ce)) {
> @@ -1939,6 +2298,10 @@ guc_create_virtual(struct intel_engine_cs **siblings, unsigned int count)
>   				 "v%dx%d", ve->base.class, count);
>   			ve->base.context_size = sibling->context_size;
>   
> +			ve->base.add_active_request =
> +				sibling->add_active_request;
> +			ve->base.remove_active_request =
> +				sibling->remove_active_request;
>   			ve->base.emit_bb_start = sibling->emit_bb_start;
>   			ve->base.emit_flush = sibling->emit_flush;
>   			ve->base.emit_init_breadcrumb =
> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_uc.c b/drivers/gpu/drm/i915/gt/uc/intel_uc.c
> index 6d8b9233214e..f0b02200aa01 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_uc.c
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_uc.c
> @@ -565,12 +565,49 @@ void intel_uc_reset_prepare(struct intel_uc *uc)
>   {
>   	struct intel_guc *guc = &uc->guc;
>   
> -	if (!intel_guc_is_ready(guc))
> +
> +	/* Nothing to do if GuC isn't supported */
> +	if (!intel_uc_supports_guc(uc))
>   		return;
>   
> +	/* Firmware expected to be running when this function is called */
> +	if (!intel_guc_is_ready(guc))
> +		goto sanitize;
> +
> +	if (intel_uc_uses_guc_submission(uc))
> +		intel_guc_submission_reset_prepare(guc);
> +
> +sanitize:
>   	__uc_sanitize(uc);
>   }
>   
> +void intel_uc_reset(struct intel_uc *uc, bool stalled)
> +{
> +	struct intel_guc *guc = &uc->guc;
> +
> +	/* Firmware can not be running when this function is called  */
> +	if (intel_uc_uses_guc_submission(uc))
> +		intel_guc_submission_reset(guc, stalled);
> +}
> +
> +void intel_uc_reset_finish(struct intel_uc *uc)
> +{
> +	struct intel_guc *guc = &uc->guc;
> +
> +	/* Firmware expected to be running when this function is called */
> +	if (intel_guc_is_fw_running(guc) && intel_uc_uses_guc_submission(uc))
> +		intel_guc_submission_reset_finish(guc);
> +}
> +
> +void intel_uc_cancel_requests(struct intel_uc *uc)
> +{
> +	struct intel_guc *guc = &uc->guc;
> +
> +	/* Firmware can not be running when this function is called  */
> +	if (intel_uc_uses_guc_submission(uc))
> +		intel_guc_submission_cancel_requests(guc);
> +}
> +
>   void intel_uc_runtime_suspend(struct intel_uc *uc)
>   {
>   	struct intel_guc *guc = &uc->guc;
> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_uc.h b/drivers/gpu/drm/i915/gt/uc/intel_uc.h
> index c4cef885e984..eaa3202192ac 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_uc.h
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_uc.h
> @@ -37,6 +37,9 @@ void intel_uc_driver_late_release(struct intel_uc *uc);
>   void intel_uc_driver_remove(struct intel_uc *uc);
>   void intel_uc_init_mmio(struct intel_uc *uc);
>   void intel_uc_reset_prepare(struct intel_uc *uc);
> +void intel_uc_reset(struct intel_uc *uc, bool stalled);
> +void intel_uc_reset_finish(struct intel_uc *uc);
> +void intel_uc_cancel_requests(struct intel_uc *uc);
>   void intel_uc_suspend(struct intel_uc *uc);
>   void intel_uc_runtime_suspend(struct intel_uc *uc);
>   int intel_uc_resume(struct intel_uc *uc);
> diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
> index dec5a35c9aa2..192784875a1d 100644
> --- a/drivers/gpu/drm/i915/i915_request.c
> +++ b/drivers/gpu/drm/i915/i915_request.c
> @@ -194,7 +194,7 @@ static bool irq_work_imm(struct irq_work *wrk)
>   	return false;
>   }
>   
> -static void __notify_execute_cb_imm(struct i915_request *rq)
> +void i915_request_notify_execute_cb_imm(struct i915_request *rq)
>   {
>   	__notify_execute_cb(rq, irq_work_imm);
>   }
> @@ -268,37 +268,6 @@ i915_request_active_engine(struct i915_request *rq,
>   	return ret;
>   }
>   
> -
> -static void remove_from_engine(struct i915_request *rq)
> -{
> -	struct intel_engine_cs *engine, *locked;
> -
> -	/*
> -	 * Virtual engines complicate acquiring the engine timeline lock,
> -	 * as their rq->engine pointer is not stable until under that
> -	 * engine lock. The simple ploy we use is to take the lock then
> -	 * check that the rq still belongs to the newly locked engine.
> -	 */
> -	locked = READ_ONCE(rq->engine);
> -	spin_lock_irq(&locked->sched_engine->lock);
> -	while (unlikely(locked != (engine = READ_ONCE(rq->engine)))) {
> -		spin_unlock(&locked->sched_engine->lock);
> -		spin_lock(&engine->sched_engine->lock);
> -		locked = engine;
> -	}
> -	list_del_init(&rq->sched.link);
> -
> -	clear_bit(I915_FENCE_FLAG_PQUEUE, &rq->fence.flags);
> -	clear_bit(I915_FENCE_FLAG_HOLD, &rq->fence.flags);
> -
> -	/* Prevent further __await_execution() registering a cb, then flush */
> -	set_bit(I915_FENCE_FLAG_ACTIVE, &rq->fence.flags);
> -
> -	spin_unlock_irq(&locked->sched_engine->lock);
> -
> -	__notify_execute_cb_imm(rq);
> -}
> -
>   static void __rq_init_watchdog(struct i915_request *rq)
>   {
>   	rq->watchdog.timer.function = NULL;
> @@ -395,9 +364,7 @@ bool i915_request_retire(struct i915_request *rq)
>   	 * after removing the breadcrumb and signaling it, so that we do not
>   	 * inadvertently attach the breadcrumb to a completed request.
>   	 */
> -	if (!list_empty(&rq->sched.link))
> -		remove_from_engine(rq);
> -	atomic_dec(&rq->context->guc_id_ref);
> +	rq->engine->remove_active_request(rq);
>   	GEM_BUG_ON(!llist_empty(&rq->execute_cb));
>   
>   	__list_del_entry(&rq->link); /* poison neither prev/next (RCU walks) */
> @@ -539,7 +506,7 @@ __await_execution(struct i915_request *rq,
>   	if (llist_add(&cb->work.node.llist, &signal->execute_cb)) {
>   		if (i915_request_is_active(signal) ||
>   		    __request_in_flight(signal))
> -			__notify_execute_cb_imm(signal);
> +			i915_request_notify_execute_cb_imm(signal);
>   	}
>   
>   	return 0;
> @@ -676,7 +643,7 @@ bool __i915_request_submit(struct i915_request *request)
>   	result = true;
>   
>   	GEM_BUG_ON(test_bit(I915_FENCE_FLAG_ACTIVE, &request->fence.flags));
> -	list_move_tail(&request->sched.link, &engine->sched_engine->requests);
> +	engine->add_active_request(request);
>   active:
>   	clear_bit(I915_FENCE_FLAG_PQUEUE, &request->fence.flags);
>   	set_bit(I915_FENCE_FLAG_ACTIVE, &request->fence.flags);
> diff --git a/drivers/gpu/drm/i915/i915_request.h b/drivers/gpu/drm/i915/i915_request.h
> index f870cd75a001..bcc6340c505e 100644
> --- a/drivers/gpu/drm/i915/i915_request.h
> +++ b/drivers/gpu/drm/i915/i915_request.h
> @@ -649,4 +649,6 @@ bool
>   i915_request_active_engine(struct i915_request *rq,
>   			   struct intel_engine_cs **active);
>   
> +void i915_request_notify_execute_cb_imm(struct i915_request *rq);
> +
>   #endif /* I915_REQUEST_H */

Matthew Brost July 15, 2021, 12:53 a.m. UTC | #2

On Mon, Jul 12, 2021 at 12:58:45PM -0700, John Harrison wrote:
> On 6/24/2021 00:05, Matthew Brost wrote:
> > Reset implementation for new GuC interface. This is the legacy reset
> > implementation which is called when the i915 owns the engine hang check.
> > Future patches will offload the engine hang check to GuC but we will
> > continue to maintain this legacy path as a fallback and this code path
> > is also required if the GuC dies.
> > 
> > With the new GuC interface it is not possible to reset individual
> > engines - it is only possible to reset the GPU entirely. This patch
> > forces an entire chip reset if any engine hangs.
> There seems to be quite a lot more code being changed in the patch than is
> described above. Sure, it's all in order to support resets but there is a
> lot happening to request/context management, support for GuC submission
> enable/disable, etc. It feels like this patch really should be split into a
> couple of prep patches followed by the actual reset support. Plus see couple
> of minor comments below.
> 

Yea, this is probably the most churned on patch we have as getting
resets to full work isn't easy. I'll fix the below comments but I don't
know if it worth spliting. Everything in the patch is required to get
resets to work and I think it is better to have in a single patch so
'git blame' can give you the whole picture.

Matt 

> > Cc: John Harrison <[e-mail]>
> > Signed-off-by: Matthew Brost <[e-mail]>
> > ---
> >   drivers/gpu/drm/i915/gt/intel_context.c       |   3 +
> >   drivers/gpu/drm/i915/gt/intel_context_types.h |   7 +
> >   drivers/gpu/drm/i915/gt/intel_engine_types.h  |   6 +
> >   .../drm/i915/gt/intel_execlists_submission.c  |  40 ++
> >   drivers/gpu/drm/i915/gt/intel_gt_pm.c         |   6 +-
> >   drivers/gpu/drm/i915/gt/intel_reset.c         |  18 +-
> >   .../gpu/drm/i915/gt/intel_ring_submission.c   |  22 +
> >   drivers/gpu/drm/i915/gt/mock_engine.c         |  31 +
> >   drivers/gpu/drm/i915/gt/uc/intel_guc.c        |  13 -
> >   drivers/gpu/drm/i915/gt/uc/intel_guc.h        |   8 +-
> >   .../gpu/drm/i915/gt/uc/intel_guc_submission.c | 581 ++++++++++++++----
> >   drivers/gpu/drm/i915/gt/uc/intel_uc.c         |  39 +-
> >   drivers/gpu/drm/i915/gt/uc/intel_uc.h         |   3 +
> >   drivers/gpu/drm/i915/i915_request.c           |  41 +-
> >   drivers/gpu/drm/i915/i915_request.h           |   2 +
> >   15 files changed, 649 insertions(+), 171 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/gt/intel_context.c b/drivers/gpu/drm/i915/gt/intel_context.c
> > index b24a1b7a3f88..2f01437056a8 100644
> > --- a/drivers/gpu/drm/i915/gt/intel_context.c
> > +++ b/drivers/gpu/drm/i915/gt/intel_context.c
> > @@ -392,6 +392,9 @@ intel_context_init(struct intel_context *ce, struct intel_engine_cs *engine)
> >   	spin_lock_init(&ce->guc_state.lock);
> >   	INIT_LIST_HEAD(&ce->guc_state.fences);
> > +	spin_lock_init(&ce->guc_active.lock);
> > +	INIT_LIST_HEAD(&ce->guc_active.requests);
> > +
> >   	ce->guc_id = GUC_INVALID_LRC_ID;
> >   	INIT_LIST_HEAD(&ce->guc_id_link);
> > diff --git a/drivers/gpu/drm/i915/gt/intel_context_types.h b/drivers/gpu/drm/i915/gt/intel_context_types.h
> > index 6945963a31ba..b63c8cf7823b 100644
> > --- a/drivers/gpu/drm/i915/gt/intel_context_types.h
> > +++ b/drivers/gpu/drm/i915/gt/intel_context_types.h
> > @@ -165,6 +165,13 @@ struct intel_context {
> >   		struct list_head fences;
> >   	} guc_state;
> > +	struct {
> > +		/** lock: protects everything in guc_active */
> > +		spinlock_t lock;
> > +		/** requests: active requests on this context */
> > +		struct list_head requests;
> > +	} guc_active;
> > +
> >   	/* GuC scheduling state that does not require a lock. */
> >   	atomic_t guc_sched_state_no_lock;
> > diff --git a/drivers/gpu/drm/i915/gt/intel_engine_types.h b/drivers/gpu/drm/i915/gt/intel_engine_types.h
> > index e7cb6a06db9d..f9d264c008e8 100644
> > --- a/drivers/gpu/drm/i915/gt/intel_engine_types.h
> > +++ b/drivers/gpu/drm/i915/gt/intel_engine_types.h
> > @@ -426,6 +426,12 @@ struct intel_engine_cs {
> >   	void		(*release)(struct intel_engine_cs *engine);
> > +	/*
> > +	 * Add / remove request from engine active tracking
> > +	 */
> > +	void		(*add_active_request)(struct i915_request *rq);
> > +	void		(*remove_active_request)(struct i915_request *rq);
> > +
> >   	struct intel_engine_execlists execlists;
> >   	/*
> > diff --git a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
> > index c10ea6080752..c301a2d088b1 100644
> > --- a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
> > +++ b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
> > @@ -3118,6 +3118,42 @@ static void execlists_park(struct intel_engine_cs *engine)
> >   	cancel_timer(&engine->execlists.preempt);
> >   }
> > +static void add_to_engine(struct i915_request *rq)
> > +{
> > +	lockdep_assert_held(&rq->engine->sched_engine->lock);
> > +	list_move_tail(&rq->sched.link, &rq->engine->sched_engine->requests);
> > +}
> > +
> > +static void remove_from_engine(struct i915_request *rq)
> > +{
> > +	struct intel_engine_cs *engine, *locked;
> > +
> > +	/*
> > +	 * Virtual engines complicate acquiring the engine timeline lock,
> > +	 * as their rq->engine pointer is not stable until under that
> > +	 * engine lock. The simple ploy we use is to take the lock then
> > +	 * check that the rq still belongs to the newly locked engine.
> > +	 */
> > +	locked = READ_ONCE(rq->engine);
> > +	spin_lock_irq(&locked->sched_engine->lock);
> > +	while (unlikely(locked != (engine = READ_ONCE(rq->engine)))) {
> > +		spin_unlock(&locked->sched_engine->lock);
> > +		spin_lock(&engine->sched_engine->lock);
> > +		locked = engine;
> > +	}
> > +	list_del_init(&rq->sched.link);
> > +
> > +	clear_bit(I915_FENCE_FLAG_PQUEUE, &rq->fence.flags);
> > +	clear_bit(I915_FENCE_FLAG_HOLD, &rq->fence.flags);
> > +
> > +	/* Prevent further __await_execution() registering a cb, then flush */
> > +	set_bit(I915_FENCE_FLAG_ACTIVE, &rq->fence.flags);
> > +
> > +	spin_unlock_irq(&locked->sched_engine->lock);
> > +
> > +	i915_request_notify_execute_cb_imm(rq);
> > +}
> > +
> >   static bool can_preempt(struct intel_engine_cs *engine)
> >   {
> >   	if (GRAPHICS_VER(engine->i915) > 8)
> > @@ -3218,6 +3254,8 @@ logical_ring_default_vfuncs(struct intel_engine_cs *engine)
> >   	engine->cops = &execlists_context_ops;
> >   	engine->request_alloc = execlists_request_alloc;
> >   	engine->bump_serial = execlist_bump_serial;
> > +	engine->add_active_request = add_to_engine;
> > +	engine->remove_active_request = remove_from_engine;
> >   	engine->reset.prepare = execlists_reset_prepare;
> >   	engine->reset.rewind = execlists_reset_rewind;
> > @@ -3912,6 +3950,8 @@ execlists_create_virtual(struct intel_engine_cs **siblings, unsigned int count)
> >   			 "v%dx%d", ve->base.class, count);
> >   		ve->base.context_size = sibling->context_size;
> > +		ve->base.add_active_request = sibling->add_active_request;
> > +		ve->base.remove_active_request = sibling->remove_active_request;
> >   		ve->base.emit_bb_start = sibling->emit_bb_start;
> >   		ve->base.emit_flush = sibling->emit_flush;
> >   		ve->base.emit_init_breadcrumb = sibling->emit_init_breadcrumb;
> > diff --git a/drivers/gpu/drm/i915/gt/intel_gt_pm.c b/drivers/gpu/drm/i915/gt/intel_gt_pm.c
> > index aef3084e8b16..463a6ae605a0 100644
> > --- a/drivers/gpu/drm/i915/gt/intel_gt_pm.c
> > +++ b/drivers/gpu/drm/i915/gt/intel_gt_pm.c
> > @@ -174,8 +174,6 @@ static void gt_sanitize(struct intel_gt *gt, bool force)
> >   	if (intel_gt_is_wedged(gt))
> >   		intel_gt_unset_wedged(gt);
> > -	intel_uc_sanitize(&gt->uc);
> > -
> >   	for_each_engine(engine, gt, id)
> >   		if (engine->reset.prepare)
> >   			engine->reset.prepare(engine);
> > @@ -191,6 +189,8 @@ static void gt_sanitize(struct intel_gt *gt, bool force)
> >   			__intel_engine_reset(engine, false);
> >   	}
> > +	intel_uc_reset(&gt->uc, false);
> > +
> >   	for_each_engine(engine, gt, id)
> >   		if (engine->reset.finish)
> >   			engine->reset.finish(engine);
> > @@ -243,6 +243,8 @@ int intel_gt_resume(struct intel_gt *gt)
> >   		goto err_wedged;
> >   	}
> > +	intel_uc_reset_finish(&gt->uc);
> > +
> >   	intel_rps_enable(&gt->rps);
> >   	intel_llc_enable(&gt->llc);
> > diff --git a/drivers/gpu/drm/i915/gt/intel_reset.c b/drivers/gpu/drm/i915/gt/intel_reset.c
> > index 72251638d4ea..2987282dff6d 100644
> > --- a/drivers/gpu/drm/i915/gt/intel_reset.c
> > +++ b/drivers/gpu/drm/i915/gt/intel_reset.c
> > @@ -826,6 +826,8 @@ static int gt_reset(struct intel_gt *gt, intel_engine_mask_t stalled_mask)
> >   		__intel_engine_reset(engine, stalled_mask & engine->mask);
> >   	local_bh_enable();
> > +	intel_uc_reset(&gt->uc, true);
> > +
> >   	intel_ggtt_restore_fences(gt->ggtt);
> >   	return err;
> > @@ -850,6 +852,8 @@ static void reset_finish(struct intel_gt *gt, intel_engine_mask_t awake)
> >   		if (awake & engine->mask)
> >   			intel_engine_pm_put(engine);
> >   	}
> > +
> > +	intel_uc_reset_finish(&gt->uc);
> >   }
> >   static void nop_submit_request(struct i915_request *request)
> > @@ -903,6 +907,7 @@ static void __intel_gt_set_wedged(struct intel_gt *gt)
> >   	for_each_engine(engine, gt, id)
> >   		if (engine->reset.cancel)
> >   			engine->reset.cancel(engine);
> > +	intel_uc_cancel_requests(&gt->uc);
> >   	local_bh_enable();
> >   	reset_finish(gt, awake);
> > @@ -1191,6 +1196,9 @@ int __intel_engine_reset_bh(struct intel_engine_cs *engine, const char *msg)
> >   	ENGINE_TRACE(engine, "flags=%lx\n", gt->reset.flags);
> >   	GEM_BUG_ON(!test_bit(I915_RESET_ENGINE + engine->id, &gt->reset.flags));
> > +	if (intel_engine_uses_guc(engine))
> > +		return -ENODEV;
> > +
> >   	if (!intel_engine_pm_get_if_awake(engine))
> >   		return 0;
> > @@ -1201,13 +1209,10 @@ int __intel_engine_reset_bh(struct intel_engine_cs *engine, const char *msg)
> >   			   "Resetting %s for %s\n", engine->name, msg);
> >   	atomic_inc(&engine->i915->gpu_error.reset_engine_count[engine->uabi_class]);
> > -	if (intel_engine_uses_guc(engine))
> > -		ret = intel_guc_reset_engine(&engine->gt->uc.guc, engine);
> > -	else
> > -		ret = intel_gt_reset_engine(engine);
> > +	ret = intel_gt_reset_engine(engine);
> >   	if (ret) {
> >   		/* If we fail here, we expect to fallback to a global reset */
> > -		ENGINE_TRACE(engine, "Failed to reset, err: %d\n", ret);
> > +		ENGINE_TRACE(engine, "Failed to reset %s, err: %d\n", engine->name, ret);
> >   		goto out;
> >   	}
> > @@ -1341,7 +1346,8 @@ void intel_gt_handle_error(struct intel_gt *gt,
> >   	 * Try engine reset when available. We fall back to full reset if
> >   	 * single reset fails.
> >   	 */
> > -	if (intel_has_reset_engine(gt) && !intel_gt_is_wedged(gt)) {
> > +	if (!intel_uc_uses_guc_submission(&gt->uc) &&
> > +	    intel_has_reset_engine(gt) && !intel_gt_is_wedged(gt)) {
> >   		local_bh_disable();
> >   		for_each_engine_masked(engine, gt, engine_mask, tmp) {
> >   			BUILD_BUG_ON(I915_RESET_MODESET >= I915_RESET_ENGINE);
> > diff --git a/drivers/gpu/drm/i915/gt/intel_ring_submission.c b/drivers/gpu/drm/i915/gt/intel_ring_submission.c
> > index e1506b280df1..99dcdc8fba12 100644
> > --- a/drivers/gpu/drm/i915/gt/intel_ring_submission.c
> > +++ b/drivers/gpu/drm/i915/gt/intel_ring_submission.c
> > @@ -1049,6 +1049,25 @@ static void ring_bump_serial(struct intel_engine_cs *engine)
> >   	engine->serial++;
> >   }
> > +static void add_to_engine(struct i915_request *rq)
> > +{
> > +	lockdep_assert_held(&rq->engine->sched_engine->lock);
> > +	list_move_tail(&rq->sched.link, &rq->engine->sched_engine->requests);
> > +}
> > +
> > +static void remove_from_engine(struct i915_request *rq)
> > +{
> > +	spin_lock_irq(&rq->engine->sched_engine->lock);
> > +	list_del_init(&rq->sched.link);
> > +
> > +	/* Prevent further __await_execution() registering a cb, then flush */
> > +	set_bit(I915_FENCE_FLAG_ACTIVE, &rq->fence.flags);
> > +
> > +	spin_unlock_irq(&rq->engine->sched_engine->lock);
> > +
> > +	i915_request_notify_execute_cb_imm(rq);
> > +}
> > +
> >   static void setup_common(struct intel_engine_cs *engine)
> >   {
> >   	struct drm_i915_private *i915 = engine->i915;
> > @@ -1066,6 +1085,9 @@ static void setup_common(struct intel_engine_cs *engine)
> >   	engine->reset.cancel = reset_cancel;
> >   	engine->reset.finish = reset_finish;
> > +	engine->add_active_request = add_to_engine;
> > +	engine->remove_active_request = remove_from_engine;
> > +
> >   	engine->cops = &ring_context_ops;
> >   	engine->request_alloc = ring_request_alloc;
> >   	engine->bump_serial = ring_bump_serial;
> > diff --git a/drivers/gpu/drm/i915/gt/mock_engine.c b/drivers/gpu/drm/i915/gt/mock_engine.c
> > index fc5a65ab1937..c12ff3a75ce6 100644
> > --- a/drivers/gpu/drm/i915/gt/mock_engine.c
> > +++ b/drivers/gpu/drm/i915/gt/mock_engine.c
> > @@ -235,6 +235,35 @@ static void mock_submit_request(struct i915_request *request)
> >   	spin_unlock_irqrestore(&engine->hw_lock, flags);
> >   }
> > +static void mock_add_to_engine(struct i915_request *rq)
> > +{
> > +	lockdep_assert_held(&rq->engine->sched_engine->lock);
> > +	list_move_tail(&rq->sched.link, &rq->engine->sched_engine->requests);
> > +}
> > +
> > +static void mock_remove_from_engine(struct i915_request *rq)
> > +{
> > +	struct intel_engine_cs *engine, *locked;
> > +
> > +	/*
> > +	 * Virtual engines complicate acquiring the engine timeline lock,
> > +	 * as their rq->engine pointer is not stable until under that
> > +	 * engine lock. The simple ploy we use is to take the lock then
> > +	 * check that the rq still belongs to the newly locked engine.
> > +	 */
> > +
> > +	locked = READ_ONCE(rq->engine);
> > +	spin_lock_irq(&locked->sched_engine->lock);
> > +	while (unlikely(locked != (engine = READ_ONCE(rq->engine)))) {
> > +		spin_unlock(&locked->sched_engine->lock);
> > +		spin_lock(&engine->sched_engine->lock);
> > +		locked = engine;
> > +	}
> > +	list_del_init(&rq->sched.link);
> > +	spin_unlock_irq(&locked->sched_engine->lock);
> > +}
> > +
> > +
> >   static void mock_reset_prepare(struct intel_engine_cs *engine)
> >   {
> >   }
> > @@ -327,6 +356,8 @@ struct intel_engine_cs *mock_engine(struct drm_i915_private *i915,
> >   	engine->base.emit_flush = mock_emit_flush;
> >   	engine->base.emit_fini_breadcrumb = mock_emit_breadcrumb;
> >   	engine->base.submit_request = mock_submit_request;
> > +	engine->base.add_active_request = mock_add_to_engine;
> > +	engine->base.remove_active_request = mock_remove_from_engine;
> >   	engine->base.reset.prepare = mock_reset_prepare;
> >   	engine->base.reset.rewind = mock_reset_rewind;
> > diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc.c b/drivers/gpu/drm/i915/gt/uc/intel_guc.c
> > index 6661dcb02239..9b09395b998f 100644
> > --- a/drivers/gpu/drm/i915/gt/uc/intel_guc.c
> > +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc.c
> > @@ -572,19 +572,6 @@ int intel_guc_suspend(struct intel_guc *guc)
> >   	return 0;
> >   }
> > -/**
> > - * intel_guc_reset_engine() - ask GuC to reset an engine
> > - * @guc:	intel_guc structure
> > - * @engine:	engine to be reset
> > - */
> > -int intel_guc_reset_engine(struct intel_guc *guc,
> > -			   struct intel_engine_cs *engine)
> > -{
> > -	/* XXX: to be implemented with submission interface rework */
> > -
> > -	return -ENODEV;
> > -}
> > -
> >   /**
> >    * intel_guc_resume() - notify GuC resuming from suspend state
> >    * @guc:	the guc
> > diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc.h b/drivers/gpu/drm/i915/gt/uc/intel_guc.h
> > index 22eb1e9cca41..40c9868762d7 100644
> > --- a/drivers/gpu/drm/i915/gt/uc/intel_guc.h
> > +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc.h
> > @@ -242,14 +242,16 @@ static inline void intel_guc_disable_msg(struct intel_guc *guc, u32 mask)
> >   int intel_guc_wait_for_idle(struct intel_guc *guc, long timeout);
> > -int intel_guc_reset_engine(struct intel_guc *guc,
> > -			   struct intel_engine_cs *engine);
> > -
> >   int intel_guc_deregister_done_process_msg(struct intel_guc *guc,
> >   					  const u32 *msg, u32 len);
> >   int intel_guc_sched_done_process_msg(struct intel_guc *guc,
> >   				     const u32 *msg, u32 len);
> > +void intel_guc_submission_reset_prepare(struct intel_guc *guc);
> > +void intel_guc_submission_reset(struct intel_guc *guc, bool stalled);
> > +void intel_guc_submission_reset_finish(struct intel_guc *guc);
> > +void intel_guc_submission_cancel_requests(struct intel_guc *guc);
> > +
> >   void intel_guc_load_status(struct intel_guc *guc, struct drm_printer *p);
> >   #endif
> > diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> > index 83058df5ba01..b8c894ad8caf 100644
> > --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> > +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> > @@ -141,7 +141,7 @@ context_wait_for_deregister_to_register(struct intel_context *ce)
> >   static inline void
> >   set_context_wait_for_deregister_to_register(struct intel_context *ce)
> >   {
> > -	/* Only should be called from guc_lrc_desc_pin() */
> > +	/* Only should be called from guc_lrc_desc_pin() without lock */
> >   	ce->guc_state.sched_state |=
> >   		SCHED_STATE_WAIT_FOR_DEREGISTER_TO_REGISTER;
> >   }
> > @@ -241,15 +241,31 @@ static int guc_lrc_desc_pool_create(struct intel_guc *guc)
> >   static void guc_lrc_desc_pool_destroy(struct intel_guc *guc)
> >   {
> > +	guc->lrc_desc_pool_vaddr = NULL;
> >   	i915_vma_unpin_and_release(&guc->lrc_desc_pool, I915_VMA_RELEASE_MAP);
> >   }
> > +static inline bool guc_submission_initialized(struct intel_guc *guc)
> > +{
> > +	return guc->lrc_desc_pool_vaddr != NULL;
> > +}
> > +
> >   static inline void reset_lrc_desc(struct intel_guc *guc, u32 id)
> >   {
> > -	struct guc_lrc_desc *desc = __get_lrc_desc(guc, id);
> > +	if (likely(guc_submission_initialized(guc))) {
> > +		struct guc_lrc_desc *desc = __get_lrc_desc(guc, id);
> > +		unsigned long flags;
> > -	memset(desc, 0, sizeof(*desc));
> > -	xa_erase_irq(&guc->context_lookup, id);
> > +		memset(desc, 0, sizeof(*desc));
> > +
> > +		/*
> > +		 * xarray API doesn't have xa_erase_irqsave wrapper, so calling
> > +		 * the lower level functions directly.
> > +		 */
> > +		xa_lock_irqsave(&guc->context_lookup, flags);
> > +		__xa_erase(&guc->context_lookup, id);
> > +		xa_unlock_irqrestore(&guc->context_lookup, flags);
> > +	}
> >   }
> >   static inline bool lrc_desc_registered(struct intel_guc *guc, u32 id)
> > @@ -260,7 +276,15 @@ static inline bool lrc_desc_registered(struct intel_guc *guc, u32 id)
> >   static inline void set_lrc_desc_registered(struct intel_guc *guc, u32 id,
> >   					   struct intel_context *ce)
> >   {
> > -	xa_store_irq(&guc->context_lookup, id, ce, GFP_ATOMIC);
> > +	unsigned long flags;
> > +
> > +	/*
> > +	 * xarray API doesn't have xa_save_irqsave wrapper, so calling the
> > +	 * lower level functions directly.
> > +	 */
> > +	xa_lock_irqsave(&guc->context_lookup, flags);
> > +	__xa_store(&guc->context_lookup, id, ce, GFP_ATOMIC);
> > +	xa_unlock_irqrestore(&guc->context_lookup, flags);
> >   }
> >   static int guc_submission_busy_loop(struct intel_guc* guc,
> > @@ -331,6 +355,8 @@ int intel_guc_wait_for_idle(struct intel_guc *guc, long timeout)
> >   					interruptible, timeout);
> >   }
> > +static int guc_lrc_desc_pin(struct intel_context *ce, bool loop);
> > +
> >   static int guc_add_request(struct intel_guc *guc, struct i915_request *rq)
> >   {
> >   	int err;
> > @@ -338,11 +364,22 @@ static int guc_add_request(struct intel_guc *guc, struct i915_request *rq)
> >   	u32 action[3];
> >   	int len = 0;
> >   	u32 g2h_len_dw = 0;
> > -	bool enabled = context_enabled(ce);
> > +	bool enabled;
> >   	GEM_BUG_ON(!atomic_read(&ce->guc_id_ref));
> >   	GEM_BUG_ON(context_guc_id_invalid(ce));
> > +	/*
> > +	 * Corner case where the GuC firmware was blown away and reloaded while
> > +	 * this context was pinned.
> > +	 */
> > +	if (unlikely(!lrc_desc_registered(guc, ce->guc_id))) {
> > +		err = guc_lrc_desc_pin(ce, false);
> > +		if (unlikely(err))
> > +			goto out;
> > +	}
> > +	enabled = context_enabled(ce);
> > +
> >   	if (!enabled) {
> >   		action[len++] = INTEL_GUC_ACTION_SCHED_CONTEXT_MODE_SET;
> >   		action[len++] = ce->guc_id;
> > @@ -365,6 +402,7 @@ static int guc_add_request(struct intel_guc *guc, struct i915_request *rq)
> >   		intel_context_put(ce);
> >   	}
> > +out:
> >   	return err;
> >   }
> > @@ -419,15 +457,10 @@ static int guc_dequeue_one_context(struct intel_guc *guc)
> >   	if (submit) {
> >   		guc_set_lrc_tail(last);
> >   resubmit:
> > -		/*
> > -		 * We only check for -EBUSY here even though it is possible for
> > -		 * -EDEADLK to be returned. If -EDEADLK is returned, the GuC has
> > -		 * died and a full GPU needs to be done. The hangcheck will
> > -		 * eventually detect that the GuC has died and trigger this
> > -		 * reset so no need to handle -EDEADLK here.
> > -		 */
> >   		ret = guc_add_request(guc, last);
> > -		if (ret == -EBUSY) {
> > +		if (unlikely(ret == -EIO))
> > +			goto deadlk;
> > +		else if (ret == -EBUSY) {
> >   			tasklet_schedule(&sched_engine->tasklet);
> >   			guc->stalled_request = last;
> >   			return false;
> > @@ -437,6 +470,11 @@ static int guc_dequeue_one_context(struct intel_guc *guc)
> >   	guc->stalled_request = NULL;
> >   	return submit;
> > +
> > +deadlk:
> > +	sched_engine->tasklet.callback = NULL;
> > +	tasklet_disable_nosync(&sched_engine->tasklet);
> > +	return false;
> >   }
> >   static void guc_submission_tasklet(struct tasklet_struct *t)
> > @@ -463,27 +501,165 @@ static void cs_irq_handler(struct intel_engine_cs *engine, u16 iir)
> >   		intel_engine_signal_breadcrumbs(engine);
> >   }
> > -static void guc_reset_prepare(struct intel_engine_cs *engine)
> > +static void __guc_context_destroy(struct intel_context *ce);
> > +static void release_guc_id(struct intel_guc *guc, struct intel_context *ce);
> > +static void guc_signal_context_fence(struct intel_context *ce);
> > +
> > +static void scrub_guc_desc_for_outstanding_g2h(struct intel_guc *guc)
> > +{
> > +	struct intel_context *ce;
> > +	unsigned long index, flags;
> > +	bool pending_disable, pending_enable, deregister, destroyed;
> > +
> > +	xa_for_each(&guc->context_lookup, index, ce) {
> > +		/* Flush context */
> > +		spin_lock_irqsave(&ce->guc_state.lock, flags);
> > +		spin_unlock_irqrestore(&ce->guc_state.lock, flags);
> > +
> > +		/*
> > +		 * Once we are at this point submission_disabled() is guaranteed
> > +		 * to visible to all callers who set the below flags (see above
> to be visible
> 
> > +		 * flush and flushes in reset_prepare). If submission_disabled()
> > +		 * is set, the caller shouldn't set these flags.
> > +		 */
> > +
> > +		destroyed = context_destroyed(ce);
> > +		pending_enable = context_pending_enable(ce);
> > +		pending_disable = context_pending_disable(ce);
> > +		deregister = context_wait_for_deregister_to_register(ce);
> > +		init_sched_state(ce);
> > +
> > +		if (pending_enable || destroyed || deregister) {
> > +			atomic_dec(&guc->outstanding_submission_g2h);
> > +			if (deregister)
> > +				guc_signal_context_fence(ce);
> > +			if (destroyed) {
> > +				release_guc_id(guc, ce);
> > +				__guc_context_destroy(ce);
> > +			}
> > +			if (pending_enable|| deregister)
> > +				intel_context_put(ce);
> > +		}
> > +
> > +		/* Not mutualy exclusive with above if statement. */
> > +		if (pending_disable) {
> > +			guc_signal_context_fence(ce);
> > +			intel_context_sched_disable_unpin(ce);
> > +			atomic_dec(&guc->outstanding_submission_g2h);
> > +			intel_context_put(ce);
> > +		}
> > +	}
> > +}
> > +
> > +static inline bool
> > +submission_disabled(struct intel_guc *guc)
> > +{
> > +	struct i915_sched_engine * const sched_engine = guc->sched_engine;
> > +
> > +	return unlikely(!__tasklet_is_enabled(&sched_engine->tasklet));
> > +}
> > +
> > +static void disable_submission(struct intel_guc *guc)
> > +{
> > +	struct i915_sched_engine * const sched_engine = guc->sched_engine;
> > +
> > +	if (__tasklet_is_enabled(&sched_engine->tasklet)) {
> > +		GEM_BUG_ON(!guc->ct.enabled);
> > +		__tasklet_disable_sync_once(&sched_engine->tasklet);
> > +		sched_engine->tasklet.callback = NULL;
> > +	}
> > +}
> > +
> > +static void enable_submission(struct intel_guc *guc)
> > +{
> > +	struct i915_sched_engine * const sched_engine = guc->sched_engine;
> > +	unsigned long flags;
> > +
> > +	spin_lock_irqsave(&guc->sched_engine->lock, flags);
> > +	sched_engine->tasklet.callback = guc_submission_tasklet;
> > +	wmb();
> > +	if (!__tasklet_is_enabled(&sched_engine->tasklet) &&
> > +	    __tasklet_enable(&sched_engine->tasklet)) {
> > +		GEM_BUG_ON(!guc->ct.enabled);
> > +
> > +		/* And kick in case we missed a new request submission. */
> > +		tasklet_hi_schedule(&sched_engine->tasklet);
> > +	}
> > +	spin_unlock_irqrestore(&guc->sched_engine->lock, flags);
> > +}
> > +
> > +static void guc_flush_submissions(struct intel_guc *guc)
> >   {
> > -	ENGINE_TRACE(engine, "\n");
> > +	struct i915_sched_engine * const sched_engine = guc->sched_engine;
> > +	unsigned long flags;
> > +
> > +	spin_lock_irqsave(&sched_engine->lock, flags);
> > +	spin_unlock_irqrestore(&sched_engine->lock, flags);
> > +}
> > +
> > +void intel_guc_submission_reset_prepare(struct intel_guc *guc)
> > +{
> > +	int i;
> > +
> > +	if (unlikely(!guc_submission_initialized(guc)))
> > +		/* Reset called during driver load? GuC not yet initialised! */
> > +		return;
> Ew. Multi-line if without braces just looks broken even if one line is just
> a comment.
> 
> > +
> > +	disable_submission(guc);
> > +	guc->interrupts.disable(guc);
> > +
> > +	/* Flush IRQ handler */
> > +	spin_lock_irq(&guc_to_gt(guc)->irq_lock);
> > +	spin_unlock_irq(&guc_to_gt(guc)->irq_lock);
> > +
> > +	guc_flush_submissions(guc);
> >   	/*
> > -	 * Prevent request submission to the hardware until we have
> > -	 * completed the reset in i915_gem_reset_finish(). If a request
> > -	 * is completed by one engine, it may then queue a request
> > -	 * to a second via its execlists->tasklet *just* as we are
> > -	 * calling engine->init_hw() and also writing the ELSP.
> > -	 * Turning off the execlists->tasklet until the reset is over
> > -	 * prevents the race.
> > -	 */
> > -	__tasklet_disable_sync_once(&engine->sched_engine->tasklet);
> > +	 * Handle any outstanding G2Hs before reset. Call IRQ handler directly
> > +	 * each pass as interrupt have been disabled. We always scrub for
> > +	 * outstanding G2H as it is possible for outstanding_submission_g2h to
> > +	 * be incremented after the context state update.
> > + 	 */
> > +	for (i = 0; i < 4 && atomic_read(&guc->outstanding_submission_g2h); ++i) {
> > +		intel_guc_to_host_event_handler(guc);
> > +#define wait_for_reset(guc, wait_var) \
> > +		guc_wait_for_pending_msg(guc, wait_var, false, (HZ / 20))
> > +		do {
> > +			wait_for_reset(guc, &guc->outstanding_submission_g2h);
> > +		} while (!list_empty(&guc->ct.requests.incoming));
> > +	}
> > +	scrub_guc_desc_for_outstanding_g2h(guc);
> >   }
> > -static void guc_reset_state(struct intel_context *ce,
> > -			    struct intel_engine_cs *engine,
> > -			    u32 head,
> > -			    bool scrub)
> > +static struct intel_engine_cs *
> > +guc_virtual_get_sibling(struct intel_engine_cs *ve, unsigned int sibling)
> >   {
> > +	struct intel_engine_cs *engine;
> > +	intel_engine_mask_t tmp, mask = ve->mask;
> > +	unsigned int num_siblings = 0;
> > +
> > +	for_each_engine_masked(engine, ve->gt, mask, tmp)
> > +		if (num_siblings++ == sibling)
> > +			return engine;
> > +
> > +	return NULL;
> > +}
> > +
> > +static inline struct intel_engine_cs *
> > +__context_to_physical_engine(struct intel_context *ce)
> > +{
> > +	struct intel_engine_cs *engine = ce->engine;
> > +
> > +	if (intel_engine_is_virtual(engine))
> > +		engine = guc_virtual_get_sibling(engine, 0);
> > +
> > +	return engine;
> > +}
> > +
> > +static void guc_reset_state(struct intel_context *ce, u32 head, bool scrub)
> > +{
> > +	struct intel_engine_cs *engine = __context_to_physical_engine(ce);
> > +
> >   	GEM_BUG_ON(!intel_context_is_pinned(ce));
> >   	/*
> > @@ -501,42 +677,147 @@ static void guc_reset_state(struct intel_context *ce,
> >   	lrc_update_regs(ce, engine, head);
> >   }
> > -static void guc_reset_rewind(struct intel_engine_cs *engine, bool stalled)
> > +static void guc_reset_nop(struct intel_engine_cs *engine)
> >   {
> > -	struct intel_engine_execlists * const execlists = &engine->execlists;
> > -	struct i915_request *rq;
> > +}
> > +
> > +static void guc_rewind_nop(struct intel_engine_cs *engine, bool stalled)
> > +{
> > +}
> > +
> > +static void
> > +__unwind_incomplete_requests(struct intel_context *ce)
> > +{
> > +	struct i915_request *rq, *rn;
> > +	struct list_head *pl;
> > +	int prio = I915_PRIORITY_INVALID;
> > +	struct i915_sched_engine * const sched_engine =
> > +		ce->engine->sched_engine;
> >   	unsigned long flags;
> > -	spin_lock_irqsave(&engine->sched_engine->lock, flags);
> > +	spin_lock_irqsave(&sched_engine->lock, flags);
> > +	spin_lock(&ce->guc_active.lock);
> > +	list_for_each_entry_safe(rq, rn,
> > +				 &ce->guc_active.requests,
> > +				 sched.link) {
> > +		if (i915_request_completed(rq))
> > +			continue;
> > +
> > +		list_del_init(&rq->sched.link);
> > +		spin_unlock(&ce->guc_active.lock);
> > +
> > +		__i915_request_unsubmit(rq);
> > +
> > +		/* Push the request back into the queue for later resubmission. */
> > +		GEM_BUG_ON(rq_prio(rq) == I915_PRIORITY_INVALID);
> > +		if (rq_prio(rq) != prio) {
> > +			prio = rq_prio(rq);
> > +			pl = i915_sched_lookup_priolist(sched_engine, prio);
> > +		}
> > +		GEM_BUG_ON(i915_sched_engine_is_empty(sched_engine));
> > +
> > +		list_add_tail(&rq->sched.link, pl);
> > +		set_bit(I915_FENCE_FLAG_PQUEUE, &rq->fence.flags);
> > -	/* Push back any incomplete requests for replay after the reset. */
> > -	rq = execlists_unwind_incomplete_requests(execlists);
> > -	if (!rq)
> > -		goto out_unlock;
> > +		spin_lock(&ce->guc_active.lock);
> > +	}
> > +	spin_unlock(&ce->guc_active.lock);
> > +	spin_unlock_irqrestore(&sched_engine->lock, flags);
> > +}
> > +
> > +static struct i915_request *context_find_active_request(struct intel_context *ce)
> > +{
> > +	struct i915_request *rq, *active = NULL;
> > +	unsigned long flags;
> > +
> > +	spin_lock_irqsave(&ce->guc_active.lock, flags);
> > +	list_for_each_entry_reverse(rq, &ce->guc_active.requests,
> > +				    sched.link) {
> > +		if (i915_request_completed(rq))
> > +			break;
> > +
> > +		active = rq;
> > +	}
> > +	spin_unlock_irqrestore(&ce->guc_active.lock, flags);
> > +
> > +	return active;
> > +}
> > +
> > +static void __guc_reset_context(struct intel_context *ce, bool stalled)
> > +{
> > +	struct i915_request *rq;
> > +	u32 head;
> > +
> > +	/*
> > +	 * GuC will implicitly mark the context as non-schedulable
> > +	 * when it sends the reset notification. Make sure our state
> > +	 * reflects this change. The context will be marked enabled
> > +	 * on resubmission.
> > +	 */
> > +	clr_context_enabled(ce);
> > +
> > +	rq = context_find_active_request(ce);
> > +	if (!rq) {
> > +		head = ce->ring->tail;
> > +		stalled = false;
> > +		goto out_replay;
> > +	}
> >   	if (!i915_request_started(rq))
> >   		stalled = false;
> > +	GEM_BUG_ON(i915_active_is_idle(&ce->active));
> > +	head = intel_ring_wrap(ce->ring, rq->head);
> >   	__i915_request_reset(rq, stalled);
> > -	guc_reset_state(rq->context, engine, rq->head, stalled);
> > -out_unlock:
> > -	spin_unlock_irqrestore(&engine->sched_engine->lock, flags);
> > +out_replay:
> > +	guc_reset_state(ce, head, stalled);
> > +	__unwind_incomplete_requests(ce);
> >   }
> > -static void guc_reset_cancel(struct intel_engine_cs *engine)
> > +void intel_guc_submission_reset(struct intel_guc *guc, bool stalled)
> > +{
> > +	struct intel_context *ce;
> > +	unsigned long index;
> > +
> > +	if (unlikely(!guc_submission_initialized(guc)))
> > +		/* Reset called during driver load? GuC not yet initialised! */
> > +		return;
> And again.
> 
> > +
> > +	xa_for_each(&guc->context_lookup, index, ce)
> > +		if (intel_context_is_pinned(ce))
> > +			__guc_reset_context(ce, stalled);
> > +
> > +	/* GuC is blown away, drop all references to contexts */
> > +	xa_destroy(&guc->context_lookup);
> > +}
> > +
> > +static void guc_cancel_context_requests(struct intel_context *ce)
> > +{
> > +	struct i915_sched_engine *sched_engine = ce_to_guc(ce)->sched_engine;
> > +	struct i915_request *rq;
> > +	unsigned long flags;
> > +
> > +	/* Mark all executing requests as skipped. */
> > +	spin_lock_irqsave(&sched_engine->lock, flags);
> > +	spin_lock(&ce->guc_active.lock);
> > +	list_for_each_entry(rq, &ce->guc_active.requests, sched.link)
> > +		i915_request_put(i915_request_mark_eio(rq));
> > +	spin_unlock(&ce->guc_active.lock);
> > +	spin_unlock_irqrestore(&sched_engine->lock, flags);
> > +}
> > +
> > +static void
> > +guc_cancel_sched_engine_requests(struct i915_sched_engine *sched_engine)
> >   {
> > -	struct i915_sched_engine * const sched_engine = engine->sched_engine;
> >   	struct i915_request *rq, *rn;
> >   	struct rb_node *rb;
> >   	unsigned long flags;
> >   	/* Can be called during boot if GuC fails to load */
> > -	if (!engine->gt)
> > +	if (!sched_engine)
> >   		return;
> > -	ENGINE_TRACE(engine, "\n");
> > -
> >   	/*
> >   	 * Before we call engine->cancel_requests(), we should have exclusive
> >   	 * access to the submission state. This is arranged for us by the
> > @@ -553,21 +834,16 @@ static void guc_reset_cancel(struct intel_engine_cs *engine)
> >   	 */
> >   	spin_lock_irqsave(&sched_engine->lock, flags);
> > -	/* Mark all executing requests as skipped. */
> > -	list_for_each_entry(rq, &sched_engine->requests, sched.link) {
> > -		i915_request_set_error_once(rq, -EIO);
> > -		i915_request_mark_complete(rq);
> > -	}
> > -
> >   	/* Flush the queued requests to the timeline list (for retiring). */
> >   	while ((rb = rb_first_cached(&sched_engine->queue))) {
> >   		struct i915_priolist *p = to_priolist(rb);
> >   		priolist_for_each_request_consume(rq, rn, p) {
> >   			list_del_init(&rq->sched.link);
> > +
> >   			__i915_request_submit(rq);
> > -			dma_fence_set_error(&rq->fence, -EIO);
> > -			i915_request_mark_complete(rq);
> > +
> > +			i915_request_put(i915_request_mark_eio(rq));
> >   		}
> >   		rb_erase_cached(&p->node, &sched_engine->queue);
> > @@ -582,14 +858,38 @@ static void guc_reset_cancel(struct intel_engine_cs *engine)
> >   	spin_unlock_irqrestore(&sched_engine->lock, flags);
> >   }
> > -static void guc_reset_finish(struct intel_engine_cs *engine)
> > +void intel_guc_submission_cancel_requests(struct intel_guc *guc)
> >   {
> > -	if (__tasklet_enable(&engine->sched_engine->tasklet))
> > -		/* And kick in case we missed a new request submission. */
> > -		tasklet_hi_schedule(&engine->sched_engine->tasklet);
> > +	struct intel_context *ce;
> > +	unsigned long index;
> > +
> > +	xa_for_each(&guc->context_lookup, index, ce)
> > +		if (intel_context_is_pinned(ce))
> > +			guc_cancel_context_requests(ce);
> > -	ENGINE_TRACE(engine, "depth->%d\n",
> > -		     atomic_read(&engine->sched_engine->tasklet.count));
> > +	guc_cancel_sched_engine_requests(guc->sched_engine);
> > +
> > +	/* GuC is blown away, drop all references to contexts */
> > +	xa_destroy(&guc->context_lookup);
> This function shares most of the code with 'intel_guc_submission_reset'. Can
> the xa clean be moved to a common helper?
> 
> John.
> 
> > +}
> > +
> > +void intel_guc_submission_reset_finish(struct intel_guc *guc)
> > +{
> > +	/* Reset called during driver load or during wedge? */
> > +	if (unlikely(!guc_submission_initialized(guc) ||
> > +		     test_bit(I915_WEDGED, &guc_to_gt(guc)->reset.flags)))
> > +		return;
> > +
> > +	/*
> > +	 * Technically possible for either of these values to be non-zero here,
> > +	 * but very unlikely + harmless. Regardless let's add a warn so we can
> > +	 * see in CI if this happens frequently / a precursor to taking down the
> > +	 * machine.
> > +	 */
> > +	GEM_WARN_ON(atomic_read(&guc->outstanding_submission_g2h));
> > +	atomic_set(&guc->outstanding_submission_g2h, 0);
> > +
> > +	enable_submission(guc);
> >   }
> >   /*
> > @@ -656,6 +956,9 @@ static int guc_bypass_tasklet_submit(struct intel_guc *guc,
> >   	else
> >   		trace_i915_request_guc_submit(rq);
> > +	if (unlikely(ret == -EIO))
> > +		disable_submission(guc);
> > +
> >   	return ret;
> >   }
> > @@ -668,7 +971,8 @@ static void guc_submit_request(struct i915_request *rq)
> >   	/* Will be called from irq-context when using foreign fences. */
> >   	spin_lock_irqsave(&sched_engine->lock, flags);
> > -	if (guc->stalled_request || !i915_sched_engine_is_empty(sched_engine))
> > +	if (submission_disabled(guc) || guc->stalled_request ||
> > +	    !i915_sched_engine_is_empty(sched_engine))
> >   		queue_request(sched_engine, rq, rq_prio(rq));
> >   	else if (guc_bypass_tasklet_submit(guc, rq) == -EBUSY)
> >   		tasklet_hi_schedule(&sched_engine->tasklet);
> > @@ -805,7 +1109,8 @@ static void unpin_guc_id(struct intel_guc *guc, struct intel_context *ce)
> >   static int __guc_action_register_context(struct intel_guc *guc,
> >   					 u32 guc_id,
> > -					 u32 offset)
> > +					 u32 offset,
> > +					 bool loop)
> >   {
> >   	u32 action[] = {
> >   		INTEL_GUC_ACTION_REGISTER_CONTEXT,
> > @@ -813,10 +1118,10 @@ static int __guc_action_register_context(struct intel_guc *guc,
> >   		offset,
> >   	};
> > -	return guc_submission_busy_loop(guc, action, ARRAY_SIZE(action), 0, true);
> > +	return guc_submission_busy_loop(guc, action, ARRAY_SIZE(action), 0, loop);
> >   }
> > -static int register_context(struct intel_context *ce)
> > +static int register_context(struct intel_context *ce, bool loop)
> >   {
> >   	struct intel_guc *guc = ce_to_guc(ce);
> >   	u32 offset = intel_guc_ggtt_offset(guc, guc->lrc_desc_pool) +
> > @@ -824,11 +1129,12 @@ static int register_context(struct intel_context *ce)
> >   	trace_intel_context_register(ce);
> > -	return __guc_action_register_context(guc, ce->guc_id, offset);
> > +	return __guc_action_register_context(guc, ce->guc_id, offset, loop);
> >   }
> >   static int __guc_action_deregister_context(struct intel_guc *guc,
> > -					   u32 guc_id)
> > +					   u32 guc_id,
> > +					   bool loop)
> >   {
> >   	u32 action[] = {
> >   		INTEL_GUC_ACTION_DEREGISTER_CONTEXT,
> > @@ -836,16 +1142,16 @@ static int __guc_action_deregister_context(struct intel_guc *guc,
> >   	};
> >   	return guc_submission_busy_loop(guc, action, ARRAY_SIZE(action),
> > -					G2H_LEN_DW_DEREGISTER_CONTEXT, true);
> > +					G2H_LEN_DW_DEREGISTER_CONTEXT, loop);
> >   }
> > -static int deregister_context(struct intel_context *ce, u32 guc_id)
> > +static int deregister_context(struct intel_context *ce, u32 guc_id, bool loop)
> >   {
> >   	struct intel_guc *guc = ce_to_guc(ce);
> >   	trace_intel_context_deregister(ce);
> > -	return __guc_action_deregister_context(guc, guc_id);
> > +	return __guc_action_deregister_context(guc, guc_id, loop);
> >   }
> >   static intel_engine_mask_t adjust_engine_mask(u8 class, intel_engine_mask_t mask)
> > @@ -874,7 +1180,7 @@ static void guc_context_policy_init(struct intel_engine_cs *engine,
> >   	desc->preemption_timeout = CONTEXT_POLICY_DEFAULT_PREEMPTION_TIME_US;
> >   }
> > -static int guc_lrc_desc_pin(struct intel_context *ce)
> > +static int guc_lrc_desc_pin(struct intel_context *ce, bool loop)
> >   {
> >   	struct intel_runtime_pm *runtime_pm =
> >   		&ce->engine->gt->i915->runtime_pm;
> > @@ -920,18 +1226,44 @@ static int guc_lrc_desc_pin(struct intel_context *ce)
> >   	 */
> >   	if (context_registered) {
> >   		trace_intel_context_steal_guc_id(ce);
> > -		set_context_wait_for_deregister_to_register(ce);
> > -		intel_context_get(ce);
> > +		if (!loop) {
> > +			set_context_wait_for_deregister_to_register(ce);
> > +			intel_context_get(ce);
> > +		} else {
> > +			bool disabled;
> > +			unsigned long flags;
> > +
> > +			/* Seal race with Reset */
> > +			spin_lock_irqsave(&ce->guc_state.lock, flags);
> > +			disabled = submission_disabled(guc);
> > +			if (likely(!disabled)) {
> > +				set_context_wait_for_deregister_to_register(ce);
> > +				intel_context_get(ce);
> > +			}
> > +			spin_unlock_irqrestore(&ce->guc_state.lock, flags);
> > +			if (unlikely(disabled)) {
> > +				reset_lrc_desc(guc, desc_idx);
> > +				return 0;	/* Will get registered later */
> > +			}
> > +		}
> >   		/*
> >   		 * If stealing the guc_id, this ce has the same guc_id as the
> >   		 * context whos guc_id was stole.
> >   		 */
> >   		with_intel_runtime_pm(runtime_pm, wakeref)
> > -			ret = deregister_context(ce, ce->guc_id);
> > +			ret = deregister_context(ce, ce->guc_id, loop);
> > +		if (unlikely(ret == -EBUSY)) {
> > +			clr_context_wait_for_deregister_to_register(ce);
> > +			intel_context_put(ce);
> > +		}
> >   	} else {
> >   		with_intel_runtime_pm(runtime_pm, wakeref)
> > -			ret = register_context(ce);
> > +			ret = register_context(ce, loop);
> > +		if (unlikely(ret == -EBUSY))
> > +			reset_lrc_desc(guc, desc_idx);
> > +		else if (unlikely(ret == -ENODEV))
> > +			ret = 0;	/* Will get registered later */
> >   	}
> >   	return ret;
> > @@ -994,7 +1326,6 @@ static void __guc_context_sched_disable(struct intel_guc *guc,
> >   	GEM_BUG_ON(guc_id == GUC_INVALID_LRC_ID);
> >   	trace_intel_context_sched_disable(ce);
> > -	intel_context_get(ce);
> >   	guc_submission_busy_loop(guc, action, ARRAY_SIZE(action),
> >   				 G2H_LEN_DW_SCHED_CONTEXT_MODE_SET, true);
> > @@ -1004,6 +1335,7 @@ static u16 prep_context_pending_disable(struct intel_context *ce)
> >   {
> >   	set_context_pending_disable(ce);
> >   	clr_context_enabled(ce);
> > +	intel_context_get(ce);
> >   	return ce->guc_id;
> >   }
> > @@ -1016,7 +1348,7 @@ static void guc_context_sched_disable(struct intel_context *ce)
> >   	u16 guc_id;
> >   	intel_wakeref_t wakeref;
> > -	if (context_guc_id_invalid(ce) ||
> > +	if (submission_disabled(guc) || context_guc_id_invalid(ce) ||
> >   	    !lrc_desc_registered(guc, ce->guc_id)) {
> >   		clr_context_enabled(ce);
> >   		goto unpin;
> > @@ -1034,6 +1366,7 @@ static void guc_context_sched_disable(struct intel_context *ce)
> >   	 * request doesn't slip through the 'context_pending_disable' fence.
> >   	 */
> >   	if (unlikely(atomic_add_unless(&ce->pin_count, -2, 2))) {
> > +		spin_unlock_irqrestore(&ce->guc_state.lock, flags);
> >   		return;
> >   	}
> >   	guc_id = prep_context_pending_disable(ce);
> > @@ -1050,19 +1383,13 @@ static void guc_context_sched_disable(struct intel_context *ce)
> >   static inline void guc_lrc_desc_unpin(struct intel_context *ce)
> >   {
> > -	struct intel_engine_cs *engine = ce->engine;
> > -	struct intel_guc *guc = &engine->gt->uc.guc;
> > -	unsigned long flags;
> > +	struct intel_guc *guc = ce_to_guc(ce);
> >   	GEM_BUG_ON(!lrc_desc_registered(guc, ce->guc_id));
> >   	GEM_BUG_ON(ce != __get_context(guc, ce->guc_id));
> >   	GEM_BUG_ON(context_enabled(ce));
> > -	spin_lock_irqsave(&ce->guc_state.lock, flags);
> > -	set_context_destroyed(ce);
> > -	spin_unlock_irqrestore(&ce->guc_state.lock, flags);
> > -
> > -	deregister_context(ce, ce->guc_id);
> > +	deregister_context(ce, ce->guc_id, true);
> >   }
> >   static void __guc_context_destroy(struct intel_context *ce)
> > @@ -1090,13 +1417,15 @@ static void guc_context_destroy(struct kref *kref)
> >   	struct intel_guc *guc = &ce->engine->gt->uc.guc;
> >   	intel_wakeref_t wakeref;
> >   	unsigned long flags;
> > +	bool disabled;
> >   	/*
> >   	 * If the guc_id is invalid this context has been stolen and we can free
> >   	 * it immediately. Also can be freed immediately if the context is not
> >   	 * registered with the GuC.
> >   	 */
> > -	if (context_guc_id_invalid(ce) ||
> > +	if (submission_disabled(guc) ||
> > +	    context_guc_id_invalid(ce) ||
> >   	    !lrc_desc_registered(guc, ce->guc_id)) {
> >   		release_guc_id(guc, ce);
> >   		__guc_context_destroy(ce);
> > @@ -1123,6 +1452,18 @@ static void guc_context_destroy(struct kref *kref)
> >   		list_del_init(&ce->guc_id_link);
> >   	spin_unlock_irqrestore(&guc->contexts_lock, flags);
> > +	/* Seal race with Reset */
> > +	spin_lock_irqsave(&ce->guc_state.lock, flags);
> > +	disabled = submission_disabled(guc);
> > +	if (likely(!disabled))
> > +		set_context_destroyed(ce);
> > +	spin_unlock_irqrestore(&ce->guc_state.lock, flags);
> > +	if (unlikely(disabled)) {
> > +		release_guc_id(guc, ce);
> > +		__guc_context_destroy(ce);
> > +		return;
> > +	}
> > +
> >   	/*
> >   	 * We defer GuC context deregistration until the context is destroyed
> >   	 * in order to save on CTBs. With this optimization ideally we only need
> > @@ -1145,6 +1486,33 @@ static int guc_context_alloc(struct intel_context *ce)
> >   	return lrc_alloc(ce, ce->engine);
> >   }
> > +static void add_to_context(struct i915_request *rq)
> > +{
> > +	struct intel_context *ce = rq->context;
> > +
> > +	spin_lock(&ce->guc_active.lock);
> > +	list_move_tail(&rq->sched.link, &ce->guc_active.requests);
> > +	spin_unlock(&ce->guc_active.lock);
> > +}
> > +
> > +static void remove_from_context(struct i915_request *rq)
> > +{
> > +	struct intel_context *ce = rq->context;
> > +
> > +	spin_lock_irq(&ce->guc_active.lock);
> > +
> > +	list_del_init(&rq->sched.link);
> > +	clear_bit(I915_FENCE_FLAG_PQUEUE, &rq->fence.flags);
> > +
> > +	/* Prevent further __await_execution() registering a cb, then flush */
> > +	set_bit(I915_FENCE_FLAG_ACTIVE, &rq->fence.flags);
> > +
> > +	spin_unlock_irq(&ce->guc_active.lock);
> > +
> > +	atomic_dec(&ce->guc_id_ref);
> > +	i915_request_notify_execute_cb_imm(rq);
> > +}
> > +
> >   static const struct intel_context_ops guc_context_ops = {
> >   	.alloc = guc_context_alloc,
> > @@ -1183,8 +1551,6 @@ static void guc_signal_context_fence(struct intel_context *ce)
> >   {
> >   	unsigned long flags;
> > -	GEM_BUG_ON(!context_wait_for_deregister_to_register(ce));
> > -
> >   	spin_lock_irqsave(&ce->guc_state.lock, flags);
> >   	clr_context_wait_for_deregister_to_register(ce);
> >   	__guc_signal_context_fence(ce);
> > @@ -1193,8 +1559,9 @@ static void guc_signal_context_fence(struct intel_context *ce)
> >   static bool context_needs_register(struct intel_context *ce, bool new_guc_id)
> >   {
> > -	return new_guc_id || test_bit(CONTEXT_LRCA_DIRTY, &ce->flags) ||
> > -		!lrc_desc_registered(ce_to_guc(ce), ce->guc_id);
> > +	return (new_guc_id || test_bit(CONTEXT_LRCA_DIRTY, &ce->flags) ||
> > +		!lrc_desc_registered(ce_to_guc(ce), ce->guc_id)) &&
> > +		!submission_disabled(ce_to_guc(ce));
> >   }
> >   static int guc_request_alloc(struct i915_request *rq)
> > @@ -1252,8 +1619,12 @@ static int guc_request_alloc(struct i915_request *rq)
> >   	if (unlikely(ret < 0))
> >   		return ret;;
> >   	if (context_needs_register(ce, !!ret)) {
> > -		ret = guc_lrc_desc_pin(ce);
> > +		ret = guc_lrc_desc_pin(ce, true);
> >   		if (unlikely(ret)) {	/* unwind */
> > +			if (ret == -EIO) {
> > +				disable_submission(guc);
> > +				goto out;	/* GPU will be reset */
> > +			}
> >   			atomic_dec(&ce->guc_id_ref);
> >   			unpin_guc_id(guc, ce);
> >   			return ret;
> > @@ -1290,20 +1661,6 @@ static int guc_request_alloc(struct i915_request *rq)
> >   	return 0;
> >   }
> > -static struct intel_engine_cs *
> > -guc_virtual_get_sibling(struct intel_engine_cs *ve, unsigned int sibling)
> > -{
> > -	struct intel_engine_cs *engine;
> > -	intel_engine_mask_t tmp, mask = ve->mask;
> > -	unsigned int num_siblings = 0;
> > -
> > -	for_each_engine_masked(engine, ve->gt, mask, tmp)
> > -		if (num_siblings++ == sibling)
> > -			return engine;
> > -
> > -	return NULL;
> > -}
> > -
> >   static int guc_virtual_context_pre_pin(struct intel_context *ce,
> >   				       struct i915_gem_ww_ctx *ww,
> >   				       void **vaddr)
> > @@ -1512,7 +1869,7 @@ static inline void guc_kernel_context_pin(struct intel_guc *guc,
> >   {
> >   	if (context_guc_id_invalid(ce))
> >   		pin_guc_id(guc, ce);
> > -	guc_lrc_desc_pin(ce);
> > +	guc_lrc_desc_pin(ce, true);
> >   }
> >   static inline void guc_init_lrc_mapping(struct intel_guc *guc)
> > @@ -1578,13 +1935,15 @@ static void guc_default_vfuncs(struct intel_engine_cs *engine)
> >   	engine->cops = &guc_context_ops;
> >   	engine->request_alloc = guc_request_alloc;
> >   	engine->bump_serial = guc_bump_serial;
> > +	engine->add_active_request = add_to_context;
> > +	engine->remove_active_request = remove_from_context;
> >   	engine->sched_engine->schedule = i915_schedule;
> > -	engine->reset.prepare = guc_reset_prepare;
> > -	engine->reset.rewind = guc_reset_rewind;
> > -	engine->reset.cancel = guc_reset_cancel;
> > -	engine->reset.finish = guc_reset_finish;
> > +	engine->reset.prepare = guc_reset_nop;
> > +	engine->reset.rewind = guc_rewind_nop;
> > +	engine->reset.cancel = guc_reset_nop;
> > +	engine->reset.finish = guc_reset_nop;
> >   	engine->emit_flush = gen8_emit_flush_xcs;
> >   	engine->emit_init_breadcrumb = gen8_emit_init_breadcrumb;
> > @@ -1757,7 +2116,7 @@ int intel_guc_deregister_done_process_msg(struct intel_guc *guc,
> >   		 * register this context.
> >   		 */
> >   		with_intel_runtime_pm(runtime_pm, wakeref)
> > -			register_context(ce);
> > +			register_context(ce, true);
> >   		guc_signal_context_fence(ce);
> >   		intel_context_put(ce);
> >   	} else if (context_destroyed(ce)) {
> > @@ -1939,6 +2298,10 @@ guc_create_virtual(struct intel_engine_cs **siblings, unsigned int count)
> >   				 "v%dx%d", ve->base.class, count);
> >   			ve->base.context_size = sibling->context_size;
> > +			ve->base.add_active_request =
> > +				sibling->add_active_request;
> > +			ve->base.remove_active_request =
> > +				sibling->remove_active_request;
> >   			ve->base.emit_bb_start = sibling->emit_bb_start;
> >   			ve->base.emit_flush = sibling->emit_flush;
> >   			ve->base.emit_init_breadcrumb =
> > diff --git a/drivers/gpu/drm/i915/gt/uc/intel_uc.c b/drivers/gpu/drm/i915/gt/uc/intel_uc.c
> > index 6d8b9233214e..f0b02200aa01 100644
> > --- a/drivers/gpu/drm/i915/gt/uc/intel_uc.c
> > +++ b/drivers/gpu/drm/i915/gt/uc/intel_uc.c
> > @@ -565,12 +565,49 @@ void intel_uc_reset_prepare(struct intel_uc *uc)
> >   {
> >   	struct intel_guc *guc = &uc->guc;
> > -	if (!intel_guc_is_ready(guc))
> > +
> > +	/* Nothing to do if GuC isn't supported */
> > +	if (!intel_uc_supports_guc(uc))
> >   		return;
> > +	/* Firmware expected to be running when this function is called */
> > +	if (!intel_guc_is_ready(guc))
> > +		goto sanitize;
> > +
> > +	if (intel_uc_uses_guc_submission(uc))
> > +		intel_guc_submission_reset_prepare(guc);
> > +
> > +sanitize:
> >   	__uc_sanitize(uc);
> >   }
> > +void intel_uc_reset(struct intel_uc *uc, bool stalled)
> > +{
> > +	struct intel_guc *guc = &uc->guc;
> > +
> > +	/* Firmware can not be running when this function is called  */
> > +	if (intel_uc_uses_guc_submission(uc))
> > +		intel_guc_submission_reset(guc, stalled);
> > +}
> > +
> > +void intel_uc_reset_finish(struct intel_uc *uc)
> > +{
> > +	struct intel_guc *guc = &uc->guc;
> > +
> > +	/* Firmware expected to be running when this function is called */
> > +	if (intel_guc_is_fw_running(guc) && intel_uc_uses_guc_submission(uc))
> > +		intel_guc_submission_reset_finish(guc);
> > +}
> > +
> > +void intel_uc_cancel_requests(struct intel_uc *uc)
> > +{
> > +	struct intel_guc *guc = &uc->guc;
> > +
> > +	/* Firmware can not be running when this function is called  */
> > +	if (intel_uc_uses_guc_submission(uc))
> > +		intel_guc_submission_cancel_requests(guc);
> > +}
> > +
> >   void intel_uc_runtime_suspend(struct intel_uc *uc)
> >   {
> >   	struct intel_guc *guc = &uc->guc;
> > diff --git a/drivers/gpu/drm/i915/gt/uc/intel_uc.h b/drivers/gpu/drm/i915/gt/uc/intel_uc.h
> > index c4cef885e984..eaa3202192ac 100644
> > --- a/drivers/gpu/drm/i915/gt/uc/intel_uc.h
> > +++ b/drivers/gpu/drm/i915/gt/uc/intel_uc.h
> > @@ -37,6 +37,9 @@ void intel_uc_driver_late_release(struct intel_uc *uc);
> >   void intel_uc_driver_remove(struct intel_uc *uc);
> >   void intel_uc_init_mmio(struct intel_uc *uc);
> >   void intel_uc_reset_prepare(struct intel_uc *uc);
> > +void intel_uc_reset(struct intel_uc *uc, bool stalled);
> > +void intel_uc_reset_finish(struct intel_uc *uc);
> > +void intel_uc_cancel_requests(struct intel_uc *uc);
> >   void intel_uc_suspend(struct intel_uc *uc);
> >   void intel_uc_runtime_suspend(struct intel_uc *uc);
> >   int intel_uc_resume(struct intel_uc *uc);
> > diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
> > index dec5a35c9aa2..192784875a1d 100644
> > --- a/drivers/gpu/drm/i915/i915_request.c
> > +++ b/drivers/gpu/drm/i915/i915_request.c
> > @@ -194,7 +194,7 @@ static bool irq_work_imm(struct irq_work *wrk)
> >   	return false;
> >   }
> > -static void __notify_execute_cb_imm(struct i915_request *rq)
> > +void i915_request_notify_execute_cb_imm(struct i915_request *rq)
> >   {
> >   	__notify_execute_cb(rq, irq_work_imm);
> >   }
> > @@ -268,37 +268,6 @@ i915_request_active_engine(struct i915_request *rq,
> >   	return ret;
> >   }
> > -
> > -static void remove_from_engine(struct i915_request *rq)
> > -{
> > -	struct intel_engine_cs *engine, *locked;
> > -
> > -	/*
> > -	 * Virtual engines complicate acquiring the engine timeline lock,
> > -	 * as their rq->engine pointer is not stable until under that
> > -	 * engine lock. The simple ploy we use is to take the lock then
> > -	 * check that the rq still belongs to the newly locked engine.
> > -	 */
> > -	locked = READ_ONCE(rq->engine);
> > -	spin_lock_irq(&locked->sched_engine->lock);
> > -	while (unlikely(locked != (engine = READ_ONCE(rq->engine)))) {
> > -		spin_unlock(&locked->sched_engine->lock);
> > -		spin_lock(&engine->sched_engine->lock);
> > -		locked = engine;
> > -	}
> > -	list_del_init(&rq->sched.link);
> > -
> > -	clear_bit(I915_FENCE_FLAG_PQUEUE, &rq->fence.flags);
> > -	clear_bit(I915_FENCE_FLAG_HOLD, &rq->fence.flags);
> > -
> > -	/* Prevent further __await_execution() registering a cb, then flush */
> > -	set_bit(I915_FENCE_FLAG_ACTIVE, &rq->fence.flags);
> > -
> > -	spin_unlock_irq(&locked->sched_engine->lock);
> > -
> > -	__notify_execute_cb_imm(rq);
> > -}
> > -
> >   static void __rq_init_watchdog(struct i915_request *rq)
> >   {
> >   	rq->watchdog.timer.function = NULL;
> > @@ -395,9 +364,7 @@ bool i915_request_retire(struct i915_request *rq)
> >   	 * after removing the breadcrumb and signaling it, so that we do not
> >   	 * inadvertently attach the breadcrumb to a completed request.
> >   	 */
> > -	if (!list_empty(&rq->sched.link))
> > -		remove_from_engine(rq);
> > -	atomic_dec(&rq->context->guc_id_ref);
> > +	rq->engine->remove_active_request(rq);
> >   	GEM_BUG_ON(!llist_empty(&rq->execute_cb));
> >   	__list_del_entry(&rq->link); /* poison neither prev/next (RCU walks) */
> > @@ -539,7 +506,7 @@ __await_execution(struct i915_request *rq,
> >   	if (llist_add(&cb->work.node.llist, &signal->execute_cb)) {
> >   		if (i915_request_is_active(signal) ||
> >   		    __request_in_flight(signal))
> > -			__notify_execute_cb_imm(signal);
> > +			i915_request_notify_execute_cb_imm(signal);
> >   	}
> >   	return 0;
> > @@ -676,7 +643,7 @@ bool __i915_request_submit(struct i915_request *request)
> >   	result = true;
> >   	GEM_BUG_ON(test_bit(I915_FENCE_FLAG_ACTIVE, &request->fence.flags));
> > -	list_move_tail(&request->sched.link, &engine->sched_engine->requests);
> > +	engine->add_active_request(request);
> >   active:
> >   	clear_bit(I915_FENCE_FLAG_PQUEUE, &request->fence.flags);
> >   	set_bit(I915_FENCE_FLAG_ACTIVE, &request->fence.flags);
> > diff --git a/drivers/gpu/drm/i915/i915_request.h b/drivers/gpu/drm/i915/i915_request.h
> > index f870cd75a001..bcc6340c505e 100644
> > --- a/drivers/gpu/drm/i915/i915_request.h
> > +++ b/drivers/gpu/drm/i915/i915_request.h
> > @@ -649,4 +649,6 @@ bool
> >   i915_request_active_engine(struct i915_request *rq,
> >   			   struct intel_engine_cs **active);
> > +void i915_request_notify_execute_cb_imm(struct i915_request *rq);
> > +
> >   #endif /* I915_REQUEST_H */
>

Tvrtko Ursulin July 15, 2021, 9:36 a.m. UTC | #3

On 24/06/2021 08:05, Matthew Brost wrote:
> Reset implementation for new GuC interface. This is the legacy reset
> implementation which is called when the i915 owns the engine hang check.
> Future patches will offload the engine hang check to GuC but we will
> continue to maintain this legacy path as a fallback and this code path
> is also required if the GuC dies.
> 
> With the new GuC interface it is not possible to reset individual
> engines - it is only possible to reset the GPU entirely. This patch
> forces an entire chip reset if any engine hangs.

No updates after my review comments on 6th of May.

At least:

1. wmb documentation

2. Spin lock cycling I either didn't understand or didn't buy the 
explanation. I don't remember seeing that pattern elsewhere in the 
driver - cycle a spinlock to make sure what was updated inside it is 
visible you said?

3. Dropping the lock protecting the list in the middle of 
list_for_each_entry_safe and just continuing to iterate like nothing 
happened. (__unwind_incomplete_requests) Again, perhaps I did not 
understand your explanation properly but you did appear to write:

"""
We only need the active lock for ce->guc_active.requests list. It is
indeed safe to drop the lock.
"""

+	spin_lock(&ce->guc_active.lock);
+	list_for_each_entry_safe(rq, rn,
+				 &ce->guc_active.requests,
+				 sched.link) {
+		if (i915_request_completed(rq))
+			continue;
+
+		list_del_init(&rq->sched.link);
+		spin_unlock(&ce->guc_active.lock);
...
+		spin_lock(&ce->guc_active.lock);
+	}

Safe iterator guards against list_del but dropping the lock means the 
state of the overall list can change so next pointer may or may not be 
valid, requests may be missed, I don't know. Needs a comment explaining 
why it is safe.

Regards,

Tvrtko

> 
> Cc: John Harrison <[e-mail]>
> Signed-off-by: Matthew Brost <[e-mail]>
> ---
>   drivers/gpu/drm/i915/gt/intel_context.c       |   3 +
>   drivers/gpu/drm/i915/gt/intel_context_types.h |   7 +
>   drivers/gpu/drm/i915/gt/intel_engine_types.h  |   6 +
>   .../drm/i915/gt/intel_execlists_submission.c  |  40 ++
>   drivers/gpu/drm/i915/gt/intel_gt_pm.c         |   6 +-
>   drivers/gpu/drm/i915/gt/intel_reset.c         |  18 +-
>   .../gpu/drm/i915/gt/intel_ring_submission.c   |  22 +
>   drivers/gpu/drm/i915/gt/mock_engine.c         |  31 +
>   drivers/gpu/drm/i915/gt/uc/intel_guc.c        |  13 -
>   drivers/gpu/drm/i915/gt/uc/intel_guc.h        |   8 +-
>   .../gpu/drm/i915/gt/uc/intel_guc_submission.c | 581 ++++++++++++++----
>   drivers/gpu/drm/i915/gt/uc/intel_uc.c         |  39 +-
>   drivers/gpu/drm/i915/gt/uc/intel_uc.h         |   3 +
>   drivers/gpu/drm/i915/i915_request.c           |  41 +-
>   drivers/gpu/drm/i915/i915_request.h           |   2 +
>   15 files changed, 649 insertions(+), 171 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/gt/intel_context.c b/drivers/gpu/drm/i915/gt/intel_context.c
> index b24a1b7a3f88..2f01437056a8 100644
> --- a/drivers/gpu/drm/i915/gt/intel_context.c
> +++ b/drivers/gpu/drm/i915/gt/intel_context.c
> @@ -392,6 +392,9 @@ intel_context_init(struct intel_context *ce, struct intel_engine_cs *engine)
>   	spin_lock_init(&ce->guc_state.lock);
>   	INIT_LIST_HEAD(&ce->guc_state.fences);
>   
> +	spin_lock_init(&ce->guc_active.lock);
> +	INIT_LIST_HEAD(&ce->guc_active.requests);
> +
>   	ce->guc_id = GUC_INVALID_LRC_ID;
>   	INIT_LIST_HEAD(&ce->guc_id_link);
>   
> diff --git a/drivers/gpu/drm/i915/gt/intel_context_types.h b/drivers/gpu/drm/i915/gt/intel_context_types.h
> index 6945963a31ba..b63c8cf7823b 100644
> --- a/drivers/gpu/drm/i915/gt/intel_context_types.h
> +++ b/drivers/gpu/drm/i915/gt/intel_context_types.h
> @@ -165,6 +165,13 @@ struct intel_context {
>   		struct list_head fences;
>   	} guc_state;
>   
> +	struct {
> +		/** lock: protects everything in guc_active */
> +		spinlock_t lock;
> +		/** requests: active requests on this context */
> +		struct list_head requests;
> +	} guc_active;
> +
>   	/* GuC scheduling state that does not require a lock. */
>   	atomic_t guc_sched_state_no_lock;
>   
> diff --git a/drivers/gpu/drm/i915/gt/intel_engine_types.h b/drivers/gpu/drm/i915/gt/intel_engine_types.h
> index e7cb6a06db9d..f9d264c008e8 100644
> --- a/drivers/gpu/drm/i915/gt/intel_engine_types.h
> +++ b/drivers/gpu/drm/i915/gt/intel_engine_types.h
> @@ -426,6 +426,12 @@ struct intel_engine_cs {
>   
>   	void		(*release)(struct intel_engine_cs *engine);
>   
> +	/*
> +	 * Add / remove request from engine active tracking
> +	 */
> +	void		(*add_active_request)(struct i915_request *rq);
> +	void		(*remove_active_request)(struct i915_request *rq);
> +
>   	struct intel_engine_execlists execlists;
>   
>   	/*
> diff --git a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
> index c10ea6080752..c301a2d088b1 100644
> --- a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
> +++ b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
> @@ -3118,6 +3118,42 @@ static void execlists_park(struct intel_engine_cs *engine)
>   	cancel_timer(&engine->execlists.preempt);
>   }
>   
> +static void add_to_engine(struct i915_request *rq)
> +{
> +	lockdep_assert_held(&rq->engine->sched_engine->lock);
> +	list_move_tail(&rq->sched.link, &rq->engine->sched_engine->requests);
> +}
> +
> +static void remove_from_engine(struct i915_request *rq)
> +{
> +	struct intel_engine_cs *engine, *locked;
> +
> +	/*
> +	 * Virtual engines complicate acquiring the engine timeline lock,
> +	 * as their rq->engine pointer is not stable until under that
> +	 * engine lock. The simple ploy we use is to take the lock then
> +	 * check that the rq still belongs to the newly locked engine.
> +	 */
> +	locked = READ_ONCE(rq->engine);
> +	spin_lock_irq(&locked->sched_engine->lock);
> +	while (unlikely(locked != (engine = READ_ONCE(rq->engine)))) {
> +		spin_unlock(&locked->sched_engine->lock);
> +		spin_lock(&engine->sched_engine->lock);
> +		locked = engine;
> +	}
> +	list_del_init(&rq->sched.link);
> +
> +	clear_bit(I915_FENCE_FLAG_PQUEUE, &rq->fence.flags);
> +	clear_bit(I915_FENCE_FLAG_HOLD, &rq->fence.flags);
> +
> +	/* Prevent further __await_execution() registering a cb, then flush */
> +	set_bit(I915_FENCE_FLAG_ACTIVE, &rq->fence.flags);
> +
> +	spin_unlock_irq(&locked->sched_engine->lock);
> +
> +	i915_request_notify_execute_cb_imm(rq);
> +}
> +
>   static bool can_preempt(struct intel_engine_cs *engine)
>   {
>   	if (GRAPHICS_VER(engine->i915) > 8)
> @@ -3218,6 +3254,8 @@ logical_ring_default_vfuncs(struct intel_engine_cs *engine)
>   	engine->cops = &execlists_context_ops;
>   	engine->request_alloc = execlists_request_alloc;
>   	engine->bump_serial = execlist_bump_serial;
> +	engine->add_active_request = add_to_engine;
> +	engine->remove_active_request = remove_from_engine;
>   
>   	engine->reset.prepare = execlists_reset_prepare;
>   	engine->reset.rewind = execlists_reset_rewind;
> @@ -3912,6 +3950,8 @@ execlists_create_virtual(struct intel_engine_cs **siblings, unsigned int count)
>   			 "v%dx%d", ve->base.class, count);
>   		ve->base.context_size = sibling->context_size;
>   
> +		ve->base.add_active_request = sibling->add_active_request;
> +		ve->base.remove_active_request = sibling->remove_active_request;
>   		ve->base.emit_bb_start = sibling->emit_bb_start;
>   		ve->base.emit_flush = sibling->emit_flush;
>   		ve->base.emit_init_breadcrumb = sibling->emit_init_breadcrumb;
> diff --git a/drivers/gpu/drm/i915/gt/intel_gt_pm.c b/drivers/gpu/drm/i915/gt/intel_gt_pm.c
> index aef3084e8b16..463a6ae605a0 100644
> --- a/drivers/gpu/drm/i915/gt/intel_gt_pm.c
> +++ b/drivers/gpu/drm/i915/gt/intel_gt_pm.c
> @@ -174,8 +174,6 @@ static void gt_sanitize(struct intel_gt *gt, bool force)
>   	if (intel_gt_is_wedged(gt))
>   		intel_gt_unset_wedged(gt);
>   
> -	intel_uc_sanitize(&gt->uc);
> -
>   	for_each_engine(engine, gt, id)
>   		if (engine->reset.prepare)
>   			engine->reset.prepare(engine);
> @@ -191,6 +189,8 @@ static void gt_sanitize(struct intel_gt *gt, bool force)
>   			__intel_engine_reset(engine, false);
>   	}
>   
> +	intel_uc_reset(&gt->uc, false);
> +
>   	for_each_engine(engine, gt, id)
>   		if (engine->reset.finish)
>   			engine->reset.finish(engine);
> @@ -243,6 +243,8 @@ int intel_gt_resume(struct intel_gt *gt)
>   		goto err_wedged;
>   	}
>   
> +	intel_uc_reset_finish(&gt->uc);
> +
>   	intel_rps_enable(&gt->rps);
>   	intel_llc_enable(&gt->llc);
>   
> diff --git a/drivers/gpu/drm/i915/gt/intel_reset.c b/drivers/gpu/drm/i915/gt/intel_reset.c
> index 72251638d4ea..2987282dff6d 100644
> --- a/drivers/gpu/drm/i915/gt/intel_reset.c
> +++ b/drivers/gpu/drm/i915/gt/intel_reset.c
> @@ -826,6 +826,8 @@ static int gt_reset(struct intel_gt *gt, intel_engine_mask_t stalled_mask)
>   		__intel_engine_reset(engine, stalled_mask & engine->mask);
>   	local_bh_enable();
>   
> +	intel_uc_reset(&gt->uc, true);
> +
>   	intel_ggtt_restore_fences(gt->ggtt);
>   
>   	return err;
> @@ -850,6 +852,8 @@ static void reset_finish(struct intel_gt *gt, intel_engine_mask_t awake)
>   		if (awake & engine->mask)
>   			intel_engine_pm_put(engine);
>   	}
> +
> +	intel_uc_reset_finish(&gt->uc);
>   }
>   
>   static void nop_submit_request(struct i915_request *request)
> @@ -903,6 +907,7 @@ static void __intel_gt_set_wedged(struct intel_gt *gt)
>   	for_each_engine(engine, gt, id)
>   		if (engine->reset.cancel)
>   			engine->reset.cancel(engine);
> +	intel_uc_cancel_requests(&gt->uc);
>   	local_bh_enable();
>   
>   	reset_finish(gt, awake);
> @@ -1191,6 +1196,9 @@ int __intel_engine_reset_bh(struct intel_engine_cs *engine, const char *msg)
>   	ENGINE_TRACE(engine, "flags=%lx\n", gt->reset.flags);
>   	GEM_BUG_ON(!test_bit(I915_RESET_ENGINE + engine->id, &gt->reset.flags));
>   
> +	if (intel_engine_uses_guc(engine))
> +		return -ENODEV;
> +
>   	if (!intel_engine_pm_get_if_awake(engine))
>   		return 0;
>   
> @@ -1201,13 +1209,10 @@ int __intel_engine_reset_bh(struct intel_engine_cs *engine, const char *msg)
>   			   "Resetting %s for %s\n", engine->name, msg);
>   	atomic_inc(&engine->i915->gpu_error.reset_engine_count[engine->uabi_class]);
>   
> -	if (intel_engine_uses_guc(engine))
> -		ret = intel_guc_reset_engine(&engine->gt->uc.guc, engine);
> -	else
> -		ret = intel_gt_reset_engine(engine);
> +	ret = intel_gt_reset_engine(engine);
>   	if (ret) {
>   		/* If we fail here, we expect to fallback to a global reset */
> -		ENGINE_TRACE(engine, "Failed to reset, err: %d\n", ret);
> +		ENGINE_TRACE(engine, "Failed to reset %s, err: %d\n", engine->name, ret);
>   		goto out;
>   	}
>   
> @@ -1341,7 +1346,8 @@ void intel_gt_handle_error(struct intel_gt *gt,
>   	 * Try engine reset when available. We fall back to full reset if
>   	 * single reset fails.
>   	 */
> -	if (intel_has_reset_engine(gt) && !intel_gt_is_wedged(gt)) {
> +	if (!intel_uc_uses_guc_submission(&gt->uc) &&
> +	    intel_has_reset_engine(gt) && !intel_gt_is_wedged(gt)) {
>   		local_bh_disable();
>   		for_each_engine_masked(engine, gt, engine_mask, tmp) {
>   			BUILD_BUG_ON(I915_RESET_MODESET >= I915_RESET_ENGINE);
> diff --git a/drivers/gpu/drm/i915/gt/intel_ring_submission.c b/drivers/gpu/drm/i915/gt/intel_ring_submission.c
> index e1506b280df1..99dcdc8fba12 100644
> --- a/drivers/gpu/drm/i915/gt/intel_ring_submission.c
> +++ b/drivers/gpu/drm/i915/gt/intel_ring_submission.c
> @@ -1049,6 +1049,25 @@ static void ring_bump_serial(struct intel_engine_cs *engine)
>   	engine->serial++;
>   }
>   
> +static void add_to_engine(struct i915_request *rq)
> +{
> +	lockdep_assert_held(&rq->engine->sched_engine->lock);
> +	list_move_tail(&rq->sched.link, &rq->engine->sched_engine->requests);
> +}
> +
> +static void remove_from_engine(struct i915_request *rq)
> +{
> +	spin_lock_irq(&rq->engine->sched_engine->lock);
> +	list_del_init(&rq->sched.link);
> +
> +	/* Prevent further __await_execution() registering a cb, then flush */
> +	set_bit(I915_FENCE_FLAG_ACTIVE, &rq->fence.flags);
> +
> +	spin_unlock_irq(&rq->engine->sched_engine->lock);
> +
> +	i915_request_notify_execute_cb_imm(rq);
> +}
> +
>   static void setup_common(struct intel_engine_cs *engine)
>   {
>   	struct drm_i915_private *i915 = engine->i915;
> @@ -1066,6 +1085,9 @@ static void setup_common(struct intel_engine_cs *engine)
>   	engine->reset.cancel = reset_cancel;
>   	engine->reset.finish = reset_finish;
>   
> +	engine->add_active_request = add_to_engine;
> +	engine->remove_active_request = remove_from_engine;
> +
>   	engine->cops = &ring_context_ops;
>   	engine->request_alloc = ring_request_alloc;
>   	engine->bump_serial = ring_bump_serial;
> diff --git a/drivers/gpu/drm/i915/gt/mock_engine.c b/drivers/gpu/drm/i915/gt/mock_engine.c
> index fc5a65ab1937..c12ff3a75ce6 100644
> --- a/drivers/gpu/drm/i915/gt/mock_engine.c
> +++ b/drivers/gpu/drm/i915/gt/mock_engine.c
> @@ -235,6 +235,35 @@ static void mock_submit_request(struct i915_request *request)
>   	spin_unlock_irqrestore(&engine->hw_lock, flags);
>   }
>   
> +static void mock_add_to_engine(struct i915_request *rq)
> +{
> +	lockdep_assert_held(&rq->engine->sched_engine->lock);
> +	list_move_tail(&rq->sched.link, &rq->engine->sched_engine->requests);
> +}
> +
> +static void mock_remove_from_engine(struct i915_request *rq)
> +{
> +	struct intel_engine_cs *engine, *locked;
> +
> +	/*
> +	 * Virtual engines complicate acquiring the engine timeline lock,
> +	 * as their rq->engine pointer is not stable until under that
> +	 * engine lock. The simple ploy we use is to take the lock then
> +	 * check that the rq still belongs to the newly locked engine.
> +	 */
> +
> +	locked = READ_ONCE(rq->engine);
> +	spin_lock_irq(&locked->sched_engine->lock);
> +	while (unlikely(locked != (engine = READ_ONCE(rq->engine)))) {
> +		spin_unlock(&locked->sched_engine->lock);
> +		spin_lock(&engine->sched_engine->lock);
> +		locked = engine;
> +	}
> +	list_del_init(&rq->sched.link);
> +	spin_unlock_irq(&locked->sched_engine->lock);
> +}
> +
> +
>   static void mock_reset_prepare(struct intel_engine_cs *engine)
>   {
>   }
> @@ -327,6 +356,8 @@ struct intel_engine_cs *mock_engine(struct drm_i915_private *i915,
>   	engine->base.emit_flush = mock_emit_flush;
>   	engine->base.emit_fini_breadcrumb = mock_emit_breadcrumb;
>   	engine->base.submit_request = mock_submit_request;
> +	engine->base.add_active_request = mock_add_to_engine;
> +	engine->base.remove_active_request = mock_remove_from_engine;
>   
>   	engine->base.reset.prepare = mock_reset_prepare;
>   	engine->base.reset.rewind = mock_reset_rewind;
> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc.c b/drivers/gpu/drm/i915/gt/uc/intel_guc.c
> index 6661dcb02239..9b09395b998f 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc.c
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc.c
> @@ -572,19 +572,6 @@ int intel_guc_suspend(struct intel_guc *guc)
>   	return 0;
>   }
>   
> -/**
> - * intel_guc_reset_engine() - ask GuC to reset an engine
> - * @guc:	intel_guc structure
> - * @engine:	engine to be reset
> - */
> -int intel_guc_reset_engine(struct intel_guc *guc,
> -			   struct intel_engine_cs *engine)
> -{
> -	/* XXX: to be implemented with submission interface rework */
> -
> -	return -ENODEV;
> -}
> -
>   /**
>    * intel_guc_resume() - notify GuC resuming from suspend state
>    * @guc:	the guc
> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc.h b/drivers/gpu/drm/i915/gt/uc/intel_guc.h
> index 22eb1e9cca41..40c9868762d7 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc.h
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc.h
> @@ -242,14 +242,16 @@ static inline void intel_guc_disable_msg(struct intel_guc *guc, u32 mask)
>   
>   int intel_guc_wait_for_idle(struct intel_guc *guc, long timeout);
>   
> -int intel_guc_reset_engine(struct intel_guc *guc,
> -			   struct intel_engine_cs *engine);
> -
>   int intel_guc_deregister_done_process_msg(struct intel_guc *guc,
>   					  const u32 *msg, u32 len);
>   int intel_guc_sched_done_process_msg(struct intel_guc *guc,
>   				     const u32 *msg, u32 len);
>   
> +void intel_guc_submission_reset_prepare(struct intel_guc *guc);
> +void intel_guc_submission_reset(struct intel_guc *guc, bool stalled);
> +void intel_guc_submission_reset_finish(struct intel_guc *guc);
> +void intel_guc_submission_cancel_requests(struct intel_guc *guc);
> +
>   void intel_guc_load_status(struct intel_guc *guc, struct drm_printer *p);
>   
>   #endif
> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> index 83058df5ba01..b8c894ad8caf 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> @@ -141,7 +141,7 @@ context_wait_for_deregister_to_register(struct intel_context *ce)
>   static inline void
>   set_context_wait_for_deregister_to_register(struct intel_context *ce)
>   {
> -	/* Only should be called from guc_lrc_desc_pin() */
> +	/* Only should be called from guc_lrc_desc_pin() without lock */
>   	ce->guc_state.sched_state |=
>   		SCHED_STATE_WAIT_FOR_DEREGISTER_TO_REGISTER;
>   }
> @@ -241,15 +241,31 @@ static int guc_lrc_desc_pool_create(struct intel_guc *guc)
>   
>   static void guc_lrc_desc_pool_destroy(struct intel_guc *guc)
>   {
> +	guc->lrc_desc_pool_vaddr = NULL;
>   	i915_vma_unpin_and_release(&guc->lrc_desc_pool, I915_VMA_RELEASE_MAP);
>   }
>   
> +static inline bool guc_submission_initialized(struct intel_guc *guc)
> +{
> +	return guc->lrc_desc_pool_vaddr != NULL;
> +}
> +
>   static inline void reset_lrc_desc(struct intel_guc *guc, u32 id)
>   {
> -	struct guc_lrc_desc *desc = __get_lrc_desc(guc, id);
> +	if (likely(guc_submission_initialized(guc))) {
> +		struct guc_lrc_desc *desc = __get_lrc_desc(guc, id);
> +		unsigned long flags;
>   
> -	memset(desc, 0, sizeof(*desc));
> -	xa_erase_irq(&guc->context_lookup, id);
> +		memset(desc, 0, sizeof(*desc));
> +
> +		/*
> +		 * xarray API doesn't have xa_erase_irqsave wrapper, so calling
> +		 * the lower level functions directly.
> +		 */
> +		xa_lock_irqsave(&guc->context_lookup, flags);
> +		__xa_erase(&guc->context_lookup, id);
> +		xa_unlock_irqrestore(&guc->context_lookup, flags);
> +	}
>   }
>   
>   static inline bool lrc_desc_registered(struct intel_guc *guc, u32 id)
> @@ -260,7 +276,15 @@ static inline bool lrc_desc_registered(struct intel_guc *guc, u32 id)
>   static inline void set_lrc_desc_registered(struct intel_guc *guc, u32 id,
>   					   struct intel_context *ce)
>   {
> -	xa_store_irq(&guc->context_lookup, id, ce, GFP_ATOMIC);
> +	unsigned long flags;
> +
> +	/*
> +	 * xarray API doesn't have xa_save_irqsave wrapper, so calling the
> +	 * lower level functions directly.
> +	 */
> +	xa_lock_irqsave(&guc->context_lookup, flags);
> +	__xa_store(&guc->context_lookup, id, ce, GFP_ATOMIC);
> +	xa_unlock_irqrestore(&guc->context_lookup, flags);
>   }
>   
>   static int guc_submission_busy_loop(struct intel_guc* guc,
> @@ -331,6 +355,8 @@ int intel_guc_wait_for_idle(struct intel_guc *guc, long timeout)
>   					interruptible, timeout);
>   }
>   
> +static int guc_lrc_desc_pin(struct intel_context *ce, bool loop);
> +
>   static int guc_add_request(struct intel_guc *guc, struct i915_request *rq)
>   {
>   	int err;
> @@ -338,11 +364,22 @@ static int guc_add_request(struct intel_guc *guc, struct i915_request *rq)
>   	u32 action[3];
>   	int len = 0;
>   	u32 g2h_len_dw = 0;
> -	bool enabled = context_enabled(ce);
> +	bool enabled;
>   
>   	GEM_BUG_ON(!atomic_read(&ce->guc_id_ref));
>   	GEM_BUG_ON(context_guc_id_invalid(ce));
>   
> +	/*
> +	 * Corner case where the GuC firmware was blown away and reloaded while
> +	 * this context was pinned.
> +	 */
> +	if (unlikely(!lrc_desc_registered(guc, ce->guc_id))) {
> +		err = guc_lrc_desc_pin(ce, false);
> +		if (unlikely(err))
> +			goto out;
> +	}
> +	enabled = context_enabled(ce);
> +
>   	if (!enabled) {
>   		action[len++] = INTEL_GUC_ACTION_SCHED_CONTEXT_MODE_SET;
>   		action[len++] = ce->guc_id;
> @@ -365,6 +402,7 @@ static int guc_add_request(struct intel_guc *guc, struct i915_request *rq)
>   		intel_context_put(ce);
>   	}
>   
> +out:
>   	return err;
>   }
>   
> @@ -419,15 +457,10 @@ static int guc_dequeue_one_context(struct intel_guc *guc)
>   	if (submit) {
>   		guc_set_lrc_tail(last);
>   resubmit:
> -		/*
> -		 * We only check for -EBUSY here even though it is possible for
> -		 * -EDEADLK to be returned. If -EDEADLK is returned, the GuC has
> -		 * died and a full GPU needs to be done. The hangcheck will
> -		 * eventually detect that the GuC has died and trigger this
> -		 * reset so no need to handle -EDEADLK here.
> -		 */
>   		ret = guc_add_request(guc, last);
> -		if (ret == -EBUSY) {
> +		if (unlikely(ret == -EIO))
> +			goto deadlk;
> +		else if (ret == -EBUSY) {
>   			tasklet_schedule(&sched_engine->tasklet);
>   			guc->stalled_request = last;
>   			return false;
> @@ -437,6 +470,11 @@ static int guc_dequeue_one_context(struct intel_guc *guc)
>   
>   	guc->stalled_request = NULL;
>   	return submit;
> +
> +deadlk:
> +	sched_engine->tasklet.callback = NULL;
> +	tasklet_disable_nosync(&sched_engine->tasklet);
> +	return false;
>   }
>   
>   static void guc_submission_tasklet(struct tasklet_struct *t)
> @@ -463,27 +501,165 @@ static void cs_irq_handler(struct intel_engine_cs *engine, u16 iir)
>   		intel_engine_signal_breadcrumbs(engine);
>   }
>   
> -static void guc_reset_prepare(struct intel_engine_cs *engine)
> +static void __guc_context_destroy(struct intel_context *ce);
> +static void release_guc_id(struct intel_guc *guc, struct intel_context *ce);
> +static void guc_signal_context_fence(struct intel_context *ce);
> +
> +static void scrub_guc_desc_for_outstanding_g2h(struct intel_guc *guc)
> +{
> +	struct intel_context *ce;
> +	unsigned long index, flags;
> +	bool pending_disable, pending_enable, deregister, destroyed;
> +
> +	xa_for_each(&guc->context_lookup, index, ce) {
> +		/* Flush context */
> +		spin_lock_irqsave(&ce->guc_state.lock, flags);
> +		spin_unlock_irqrestore(&ce->guc_state.lock, flags);
> +
> +		/*
> +		 * Once we are at this point submission_disabled() is guaranteed
> +		 * to visible to all callers who set the below flags (see above
> +		 * flush and flushes in reset_prepare). If submission_disabled()
> +		 * is set, the caller shouldn't set these flags.
> +		 */
> +
> +		destroyed = context_destroyed(ce);
> +		pending_enable = context_pending_enable(ce);
> +		pending_disable = context_pending_disable(ce);
> +		deregister = context_wait_for_deregister_to_register(ce);
> +		init_sched_state(ce);
> +
> +		if (pending_enable || destroyed || deregister) {
> +			atomic_dec(&guc->outstanding_submission_g2h);
> +			if (deregister)
> +				guc_signal_context_fence(ce);
> +			if (destroyed) {
> +				release_guc_id(guc, ce);
> +				__guc_context_destroy(ce);
> +			}
> +			if (pending_enable|| deregister)
> +				intel_context_put(ce);
> +		}
> +
> +		/* Not mutualy exclusive with above if statement. */
> +		if (pending_disable) {
> +			guc_signal_context_fence(ce);
> +			intel_context_sched_disable_unpin(ce);
> +			atomic_dec(&guc->outstanding_submission_g2h);
> +			intel_context_put(ce);
> +		}
> +	}
> +}
> +
> +static inline bool
> +submission_disabled(struct intel_guc *guc)
> +{
> +	struct i915_sched_engine * const sched_engine = guc->sched_engine;
> +
> +	return unlikely(!__tasklet_is_enabled(&sched_engine->tasklet));
> +}
> +
> +static void disable_submission(struct intel_guc *guc)
> +{
> +	struct i915_sched_engine * const sched_engine = guc->sched_engine;
> +
> +	if (__tasklet_is_enabled(&sched_engine->tasklet)) {
> +		GEM_BUG_ON(!guc->ct.enabled);
> +		__tasklet_disable_sync_once(&sched_engine->tasklet);
> +		sched_engine->tasklet.callback = NULL;
> +	}
> +}
> +
> +static void enable_submission(struct intel_guc *guc)
> +{
> +	struct i915_sched_engine * const sched_engine = guc->sched_engine;
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&guc->sched_engine->lock, flags);
> +	sched_engine->tasklet.callback = guc_submission_tasklet;
> +	wmb();
> +	if (!__tasklet_is_enabled(&sched_engine->tasklet) &&
> +	    __tasklet_enable(&sched_engine->tasklet)) {
> +		GEM_BUG_ON(!guc->ct.enabled);
> +
> +		/* And kick in case we missed a new request submission. */
> +		tasklet_hi_schedule(&sched_engine->tasklet);
> +	}
> +	spin_unlock_irqrestore(&guc->sched_engine->lock, flags);
> +}
> +
> +static void guc_flush_submissions(struct intel_guc *guc)
>   {
> -	ENGINE_TRACE(engine, "\n");
> +	struct i915_sched_engine * const sched_engine = guc->sched_engine;
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&sched_engine->lock, flags);
> +	spin_unlock_irqrestore(&sched_engine->lock, flags);
> +}
> +
> +void intel_guc_submission_reset_prepare(struct intel_guc *guc)
> +{
> +	int i;
> +
> +	if (unlikely(!guc_submission_initialized(guc)))
> +		/* Reset called during driver load? GuC not yet initialised! */
> +		return;
> +
> +	disable_submission(guc);
> +	guc->interrupts.disable(guc);
> +
> +	/* Flush IRQ handler */
> +	spin_lock_irq(&guc_to_gt(guc)->irq_lock);
> +	spin_unlock_irq(&guc_to_gt(guc)->irq_lock);
> +
> +	guc_flush_submissions(guc);
>   
>   	/*
> -	 * Prevent request submission to the hardware until we have
> -	 * completed the reset in i915_gem_reset_finish(). If a request
> -	 * is completed by one engine, it may then queue a request
> -	 * to a second via its execlists->tasklet *just* as we are
> -	 * calling engine->init_hw() and also writing the ELSP.
> -	 * Turning off the execlists->tasklet until the reset is over
> -	 * prevents the race.
> -	 */
> -	__tasklet_disable_sync_once(&engine->sched_engine->tasklet);
> +	 * Handle any outstanding G2Hs before reset. Call IRQ handler directly
> +	 * each pass as interrupt have been disabled. We always scrub for
> +	 * outstanding G2H as it is possible for outstanding_submission_g2h to
> +	 * be incremented after the context state update.
> + 	 */
> +	for (i = 0; i < 4 && atomic_read(&guc->outstanding_submission_g2h); ++i) {
> +		intel_guc_to_host_event_handler(guc);
> +#define wait_for_reset(guc, wait_var) \
> +		guc_wait_for_pending_msg(guc, wait_var, false, (HZ / 20))
> +		do {
> +			wait_for_reset(guc, &guc->outstanding_submission_g2h);
> +		} while (!list_empty(&guc->ct.requests.incoming));
> +	}
> +	scrub_guc_desc_for_outstanding_g2h(guc);
>   }
>   
> -static void guc_reset_state(struct intel_context *ce,
> -			    struct intel_engine_cs *engine,
> -			    u32 head,
> -			    bool scrub)
> +static struct intel_engine_cs *
> +guc_virtual_get_sibling(struct intel_engine_cs *ve, unsigned int sibling)
>   {
> +	struct intel_engine_cs *engine;
> +	intel_engine_mask_t tmp, mask = ve->mask;
> +	unsigned int num_siblings = 0;
> +
> +	for_each_engine_masked(engine, ve->gt, mask, tmp)
> +		if (num_siblings++ == sibling)
> +			return engine;
> +
> +	return NULL;
> +}
> +
> +static inline struct intel_engine_cs *
> +__context_to_physical_engine(struct intel_context *ce)
> +{
> +	struct intel_engine_cs *engine = ce->engine;
> +
> +	if (intel_engine_is_virtual(engine))
> +		engine = guc_virtual_get_sibling(engine, 0);
> +
> +	return engine;
> +}
> +
> +static void guc_reset_state(struct intel_context *ce, u32 head, bool scrub)
> +{
> +	struct intel_engine_cs *engine = __context_to_physical_engine(ce);
> +
>   	GEM_BUG_ON(!intel_context_is_pinned(ce));
>   
>   	/*
> @@ -501,42 +677,147 @@ static void guc_reset_state(struct intel_context *ce,
>   	lrc_update_regs(ce, engine, head);
>   }
>   
> -static void guc_reset_rewind(struct intel_engine_cs *engine, bool stalled)
> +static void guc_reset_nop(struct intel_engine_cs *engine)
>   {
> -	struct intel_engine_execlists * const execlists = &engine->execlists;
> -	struct i915_request *rq;
> +}
> +
> +static void guc_rewind_nop(struct intel_engine_cs *engine, bool stalled)
> +{
> +}
> +
> +static void
> +__unwind_incomplete_requests(struct intel_context *ce)
> +{
> +	struct i915_request *rq, *rn;
> +	struct list_head *pl;
> +	int prio = I915_PRIORITY_INVALID;
> +	struct i915_sched_engine * const sched_engine =
> +		ce->engine->sched_engine;
>   	unsigned long flags;
>   
> -	spin_lock_irqsave(&engine->sched_engine->lock, flags);
> +	spin_lock_irqsave(&sched_engine->lock, flags);
> +	spin_lock(&ce->guc_active.lock);
> +	list_for_each_entry_safe(rq, rn,
> +				 &ce->guc_active.requests,
> +				 sched.link) {
> +		if (i915_request_completed(rq))
> +			continue;
> +
> +		list_del_init(&rq->sched.link);
> +		spin_unlock(&ce->guc_active.lock);
> +
> +		__i915_request_unsubmit(rq);
> +
> +		/* Push the request back into the queue for later resubmission. */
> +		GEM_BUG_ON(rq_prio(rq) == I915_PRIORITY_INVALID);
> +		if (rq_prio(rq) != prio) {
> +			prio = rq_prio(rq);
> +			pl = i915_sched_lookup_priolist(sched_engine, prio);
> +		}
> +		GEM_BUG_ON(i915_sched_engine_is_empty(sched_engine));
> +
> +		list_add_tail(&rq->sched.link, pl);
> +		set_bit(I915_FENCE_FLAG_PQUEUE, &rq->fence.flags);
>   
> -	/* Push back any incomplete requests for replay after the reset. */
> -	rq = execlists_unwind_incomplete_requests(execlists);
> -	if (!rq)
> -		goto out_unlock;
> +		spin_lock(&ce->guc_active.lock);
> +	}
> +	spin_unlock(&ce->guc_active.lock);
> +	spin_unlock_irqrestore(&sched_engine->lock, flags);
> +}
> +
> +static struct i915_request *context_find_active_request(struct intel_context *ce)
> +{
> +	struct i915_request *rq, *active = NULL;
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&ce->guc_active.lock, flags);
> +	list_for_each_entry_reverse(rq, &ce->guc_active.requests,
> +				    sched.link) {
> +		if (i915_request_completed(rq))
> +			break;
> +
> +		active = rq;
> +	}
> +	spin_unlock_irqrestore(&ce->guc_active.lock, flags);
> +
> +	return active;
> +}
> +
> +static void __guc_reset_context(struct intel_context *ce, bool stalled)
> +{
> +	struct i915_request *rq;
> +	u32 head;
> +
> +	/*
> +	 * GuC will implicitly mark the context as non-schedulable
> +	 * when it sends the reset notification. Make sure our state
> +	 * reflects this change. The context will be marked enabled
> +	 * on resubmission.
> +	 */
> +	clr_context_enabled(ce);
> +
> +	rq = context_find_active_request(ce);
> +	if (!rq) {
> +		head = ce->ring->tail;
> +		stalled = false;
> +		goto out_replay;
> +	}
>   
>   	if (!i915_request_started(rq))
>   		stalled = false;
>   
> +	GEM_BUG_ON(i915_active_is_idle(&ce->active));
> +	head = intel_ring_wrap(ce->ring, rq->head);
>   	__i915_request_reset(rq, stalled);
> -	guc_reset_state(rq->context, engine, rq->head, stalled);
>   
> -out_unlock:
> -	spin_unlock_irqrestore(&engine->sched_engine->lock, flags);
> +out_replay:
> +	guc_reset_state(ce, head, stalled);
> +	__unwind_incomplete_requests(ce);
>   }
>   
> -static void guc_reset_cancel(struct intel_engine_cs *engine)
> +void intel_guc_submission_reset(struct intel_guc *guc, bool stalled)
> +{
> +	struct intel_context *ce;
> +	unsigned long index;
> +
> +	if (unlikely(!guc_submission_initialized(guc)))
> +		/* Reset called during driver load? GuC not yet initialised! */
> +		return;
> +
> +	xa_for_each(&guc->context_lookup, index, ce)
> +		if (intel_context_is_pinned(ce))
> +			__guc_reset_context(ce, stalled);
> +
> +	/* GuC is blown away, drop all references to contexts */
> +	xa_destroy(&guc->context_lookup);
> +}
> +
> +static void guc_cancel_context_requests(struct intel_context *ce)
> +{
> +	struct i915_sched_engine *sched_engine = ce_to_guc(ce)->sched_engine;
> +	struct i915_request *rq;
> +	unsigned long flags;
> +
> +	/* Mark all executing requests as skipped. */
> +	spin_lock_irqsave(&sched_engine->lock, flags);
> +	spin_lock(&ce->guc_active.lock);
> +	list_for_each_entry(rq, &ce->guc_active.requests, sched.link)
> +		i915_request_put(i915_request_mark_eio(rq));
> +	spin_unlock(&ce->guc_active.lock);
> +	spin_unlock_irqrestore(&sched_engine->lock, flags);
> +}
> +
> +static void
> +guc_cancel_sched_engine_requests(struct i915_sched_engine *sched_engine)
>   {
> -	struct i915_sched_engine * const sched_engine = engine->sched_engine;
>   	struct i915_request *rq, *rn;
>   	struct rb_node *rb;
>   	unsigned long flags;
>   
>   	/* Can be called during boot if GuC fails to load */
> -	if (!engine->gt)
> +	if (!sched_engine)
>   		return;
>   
> -	ENGINE_TRACE(engine, "\n");
> -
>   	/*
>   	 * Before we call engine->cancel_requests(), we should have exclusive
>   	 * access to the submission state. This is arranged for us by the
> @@ -553,21 +834,16 @@ static void guc_reset_cancel(struct intel_engine_cs *engine)
>   	 */
>   	spin_lock_irqsave(&sched_engine->lock, flags);
>   
> -	/* Mark all executing requests as skipped. */
> -	list_for_each_entry(rq, &sched_engine->requests, sched.link) {
> -		i915_request_set_error_once(rq, -EIO);
> -		i915_request_mark_complete(rq);
> -	}
> -
>   	/* Flush the queued requests to the timeline list (for retiring). */
>   	while ((rb = rb_first_cached(&sched_engine->queue))) {
>   		struct i915_priolist *p = to_priolist(rb);
>   
>   		priolist_for_each_request_consume(rq, rn, p) {
>   			list_del_init(&rq->sched.link);
> +
>   			__i915_request_submit(rq);
> -			dma_fence_set_error(&rq->fence, -EIO);
> -			i915_request_mark_complete(rq);
> +
> +			i915_request_put(i915_request_mark_eio(rq));
>   		}
>   
>   		rb_erase_cached(&p->node, &sched_engine->queue);
> @@ -582,14 +858,38 @@ static void guc_reset_cancel(struct intel_engine_cs *engine)
>   	spin_unlock_irqrestore(&sched_engine->lock, flags);
>   }
>   
> -static void guc_reset_finish(struct intel_engine_cs *engine)
> +void intel_guc_submission_cancel_requests(struct intel_guc *guc)
>   {
> -	if (__tasklet_enable(&engine->sched_engine->tasklet))
> -		/* And kick in case we missed a new request submission. */
> -		tasklet_hi_schedule(&engine->sched_engine->tasklet);
> +	struct intel_context *ce;
> +	unsigned long index;
> +
> +	xa_for_each(&guc->context_lookup, index, ce)
> +		if (intel_context_is_pinned(ce))
> +			guc_cancel_context_requests(ce);
>   
> -	ENGINE_TRACE(engine, "depth->%d\n",
> -		     atomic_read(&engine->sched_engine->tasklet.count));
> +	guc_cancel_sched_engine_requests(guc->sched_engine);
> +
> +	/* GuC is blown away, drop all references to contexts */
> +	xa_destroy(&guc->context_lookup);
> +}
> +
> +void intel_guc_submission_reset_finish(struct intel_guc *guc)
> +{
> +	/* Reset called during driver load or during wedge? */
> +	if (unlikely(!guc_submission_initialized(guc) ||
> +		     test_bit(I915_WEDGED, &guc_to_gt(guc)->reset.flags)))
> +		return;
> +
> +	/*
> +	 * Technically possible for either of these values to be non-zero here,
> +	 * but very unlikely + harmless. Regardless let's add a warn so we can
> +	 * see in CI if this happens frequently / a precursor to taking down the
> +	 * machine.
> +	 */
> +	GEM_WARN_ON(atomic_read(&guc->outstanding_submission_g2h));
> +	atomic_set(&guc->outstanding_submission_g2h, 0);
> +
> +	enable_submission(guc);
>   }
>   
>   /*
> @@ -656,6 +956,9 @@ static int guc_bypass_tasklet_submit(struct intel_guc *guc,
>   	else
>   		trace_i915_request_guc_submit(rq);
>   
> +	if (unlikely(ret == -EIO))
> +		disable_submission(guc);
> +
>   	return ret;
>   }
>   
> @@ -668,7 +971,8 @@ static void guc_submit_request(struct i915_request *rq)
>   	/* Will be called from irq-context when using foreign fences. */
>   	spin_lock_irqsave(&sched_engine->lock, flags);
>   
> -	if (guc->stalled_request || !i915_sched_engine_is_empty(sched_engine))
> +	if (submission_disabled(guc) || guc->stalled_request ||
> +	    !i915_sched_engine_is_empty(sched_engine))
>   		queue_request(sched_engine, rq, rq_prio(rq));
>   	else if (guc_bypass_tasklet_submit(guc, rq) == -EBUSY)
>   		tasklet_hi_schedule(&sched_engine->tasklet);
> @@ -805,7 +1109,8 @@ static void unpin_guc_id(struct intel_guc *guc, struct intel_context *ce)
>   
>   static int __guc_action_register_context(struct intel_guc *guc,
>   					 u32 guc_id,
> -					 u32 offset)
> +					 u32 offset,
> +					 bool loop)
>   {
>   	u32 action[] = {
>   		INTEL_GUC_ACTION_REGISTER_CONTEXT,
> @@ -813,10 +1118,10 @@ static int __guc_action_register_context(struct intel_guc *guc,
>   		offset,
>   	};
>   
> -	return guc_submission_busy_loop(guc, action, ARRAY_SIZE(action), 0, true);
> +	return guc_submission_busy_loop(guc, action, ARRAY_SIZE(action), 0, loop);
>   }
>   
> -static int register_context(struct intel_context *ce)
> +static int register_context(struct intel_context *ce, bool loop)
>   {
>   	struct intel_guc *guc = ce_to_guc(ce);
>   	u32 offset = intel_guc_ggtt_offset(guc, guc->lrc_desc_pool) +
> @@ -824,11 +1129,12 @@ static int register_context(struct intel_context *ce)
>   
>   	trace_intel_context_register(ce);
>   
> -	return __guc_action_register_context(guc, ce->guc_id, offset);
> +	return __guc_action_register_context(guc, ce->guc_id, offset, loop);
>   }
>   
>   static int __guc_action_deregister_context(struct intel_guc *guc,
> -					   u32 guc_id)
> +					   u32 guc_id,
> +					   bool loop)
>   {
>   	u32 action[] = {
>   		INTEL_GUC_ACTION_DEREGISTER_CONTEXT,
> @@ -836,16 +1142,16 @@ static int __guc_action_deregister_context(struct intel_guc *guc,
>   	};
>   
>   	return guc_submission_busy_loop(guc, action, ARRAY_SIZE(action),
> -					G2H_LEN_DW_DEREGISTER_CONTEXT, true);
> +					G2H_LEN_DW_DEREGISTER_CONTEXT, loop);
>   }
>   
> -static int deregister_context(struct intel_context *ce, u32 guc_id)
> +static int deregister_context(struct intel_context *ce, u32 guc_id, bool loop)
>   {
>   	struct intel_guc *guc = ce_to_guc(ce);
>   
>   	trace_intel_context_deregister(ce);
>   
> -	return __guc_action_deregister_context(guc, guc_id);
> +	return __guc_action_deregister_context(guc, guc_id, loop);
>   }
>   
>   static intel_engine_mask_t adjust_engine_mask(u8 class, intel_engine_mask_t mask)
> @@ -874,7 +1180,7 @@ static void guc_context_policy_init(struct intel_engine_cs *engine,
>   	desc->preemption_timeout = CONTEXT_POLICY_DEFAULT_PREEMPTION_TIME_US;
>   }
>   
> -static int guc_lrc_desc_pin(struct intel_context *ce)
> +static int guc_lrc_desc_pin(struct intel_context *ce, bool loop)
>   {
>   	struct intel_runtime_pm *runtime_pm =
>   		&ce->engine->gt->i915->runtime_pm;
> @@ -920,18 +1226,44 @@ static int guc_lrc_desc_pin(struct intel_context *ce)
>   	 */
>   	if (context_registered) {
>   		trace_intel_context_steal_guc_id(ce);
> -		set_context_wait_for_deregister_to_register(ce);
> -		intel_context_get(ce);
> +		if (!loop) {
> +			set_context_wait_for_deregister_to_register(ce);
> +			intel_context_get(ce);
> +		} else {
> +			bool disabled;
> +			unsigned long flags;
> +
> +			/* Seal race with Reset */
> +			spin_lock_irqsave(&ce->guc_state.lock, flags);
> +			disabled = submission_disabled(guc);
> +			if (likely(!disabled)) {
> +				set_context_wait_for_deregister_to_register(ce);
> +				intel_context_get(ce);
> +			}
> +			spin_unlock_irqrestore(&ce->guc_state.lock, flags);
> +			if (unlikely(disabled)) {
> +				reset_lrc_desc(guc, desc_idx);
> +				return 0;	/* Will get registered later */
> +			}
> +		}
>   
>   		/*
>   		 * If stealing the guc_id, this ce has the same guc_id as the
>   		 * context whos guc_id was stole.
>   		 */
>   		with_intel_runtime_pm(runtime_pm, wakeref)
> -			ret = deregister_context(ce, ce->guc_id);
> +			ret = deregister_context(ce, ce->guc_id, loop);
> +		if (unlikely(ret == -EBUSY)) {
> +			clr_context_wait_for_deregister_to_register(ce);
> +			intel_context_put(ce);
> +		}
>   	} else {
>   		with_intel_runtime_pm(runtime_pm, wakeref)
> -			ret = register_context(ce);
> +			ret = register_context(ce, loop);
> +		if (unlikely(ret == -EBUSY))
> +			reset_lrc_desc(guc, desc_idx);
> +		else if (unlikely(ret == -ENODEV))
> +			ret = 0;	/* Will get registered later */
>   	}
>   
>   	return ret;
> @@ -994,7 +1326,6 @@ static void __guc_context_sched_disable(struct intel_guc *guc,
>   	GEM_BUG_ON(guc_id == GUC_INVALID_LRC_ID);
>   
>   	trace_intel_context_sched_disable(ce);
> -	intel_context_get(ce);
>   
>   	guc_submission_busy_loop(guc, action, ARRAY_SIZE(action),
>   				 G2H_LEN_DW_SCHED_CONTEXT_MODE_SET, true);
> @@ -1004,6 +1335,7 @@ static u16 prep_context_pending_disable(struct intel_context *ce)
>   {
>   	set_context_pending_disable(ce);
>   	clr_context_enabled(ce);
> +	intel_context_get(ce);
>   
>   	return ce->guc_id;
>   }
> @@ -1016,7 +1348,7 @@ static void guc_context_sched_disable(struct intel_context *ce)
>   	u16 guc_id;
>   	intel_wakeref_t wakeref;
>   
> -	if (context_guc_id_invalid(ce) ||
> +	if (submission_disabled(guc) || context_guc_id_invalid(ce) ||
>   	    !lrc_desc_registered(guc, ce->guc_id)) {
>   		clr_context_enabled(ce);
>   		goto unpin;
> @@ -1034,6 +1366,7 @@ static void guc_context_sched_disable(struct intel_context *ce)
>   	 * request doesn't slip through the 'context_pending_disable' fence.
>   	 */
>   	if (unlikely(atomic_add_unless(&ce->pin_count, -2, 2))) {
> +		spin_unlock_irqrestore(&ce->guc_state.lock, flags);
>   		return;
>   	}
>   	guc_id = prep_context_pending_disable(ce);
> @@ -1050,19 +1383,13 @@ static void guc_context_sched_disable(struct intel_context *ce)
>   
>   static inline void guc_lrc_desc_unpin(struct intel_context *ce)
>   {
> -	struct intel_engine_cs *engine = ce->engine;
> -	struct intel_guc *guc = &engine->gt->uc.guc;
> -	unsigned long flags;
> +	struct intel_guc *guc = ce_to_guc(ce);
>   
>   	GEM_BUG_ON(!lrc_desc_registered(guc, ce->guc_id));
>   	GEM_BUG_ON(ce != __get_context(guc, ce->guc_id));
>   	GEM_BUG_ON(context_enabled(ce));
>   
> -	spin_lock_irqsave(&ce->guc_state.lock, flags);
> -	set_context_destroyed(ce);
> -	spin_unlock_irqrestore(&ce->guc_state.lock, flags);
> -
> -	deregister_context(ce, ce->guc_id);
> +	deregister_context(ce, ce->guc_id, true);
>   }
>   
>   static void __guc_context_destroy(struct intel_context *ce)
> @@ -1090,13 +1417,15 @@ static void guc_context_destroy(struct kref *kref)
>   	struct intel_guc *guc = &ce->engine->gt->uc.guc;
>   	intel_wakeref_t wakeref;
>   	unsigned long flags;
> +	bool disabled;
>   
>   	/*
>   	 * If the guc_id is invalid this context has been stolen and we can free
>   	 * it immediately. Also can be freed immediately if the context is not
>   	 * registered with the GuC.
>   	 */
> -	if (context_guc_id_invalid(ce) ||
> +	if (submission_disabled(guc) ||
> +	    context_guc_id_invalid(ce) ||
>   	    !lrc_desc_registered(guc, ce->guc_id)) {
>   		release_guc_id(guc, ce);
>   		__guc_context_destroy(ce);
> @@ -1123,6 +1452,18 @@ static void guc_context_destroy(struct kref *kref)
>   		list_del_init(&ce->guc_id_link);
>   	spin_unlock_irqrestore(&guc->contexts_lock, flags);
>   
> +	/* Seal race with Reset */
> +	spin_lock_irqsave(&ce->guc_state.lock, flags);
> +	disabled = submission_disabled(guc);
> +	if (likely(!disabled))
> +		set_context_destroyed(ce);
> +	spin_unlock_irqrestore(&ce->guc_state.lock, flags);
> +	if (unlikely(disabled)) {
> +		release_guc_id(guc, ce);
> +		__guc_context_destroy(ce);
> +		return;
> +	}
> +
>   	/*
>   	 * We defer GuC context deregistration until the context is destroyed
>   	 * in order to save on CTBs. With this optimization ideally we only need
> @@ -1145,6 +1486,33 @@ static int guc_context_alloc(struct intel_context *ce)
>   	return lrc_alloc(ce, ce->engine);
>   }
>   
> +static void add_to_context(struct i915_request *rq)
> +{
> +	struct intel_context *ce = rq->context;
> +
> +	spin_lock(&ce->guc_active.lock);
> +	list_move_tail(&rq->sched.link, &ce->guc_active.requests);
> +	spin_unlock(&ce->guc_active.lock);
> +}
> +
> +static void remove_from_context(struct i915_request *rq)
> +{
> +	struct intel_context *ce = rq->context;
> +
> +	spin_lock_irq(&ce->guc_active.lock);
> +
> +	list_del_init(&rq->sched.link);
> +	clear_bit(I915_FENCE_FLAG_PQUEUE, &rq->fence.flags);
> +
> +	/* Prevent further __await_execution() registering a cb, then flush */
> +	set_bit(I915_FENCE_FLAG_ACTIVE, &rq->fence.flags);
> +
> +	spin_unlock_irq(&ce->guc_active.lock);
> +
> +	atomic_dec(&ce->guc_id_ref);
> +	i915_request_notify_execute_cb_imm(rq);
> +}
> +
>   static const struct intel_context_ops guc_context_ops = {
>   	.alloc = guc_context_alloc,
>   
> @@ -1183,8 +1551,6 @@ static void guc_signal_context_fence(struct intel_context *ce)
>   {
>   	unsigned long flags;
>   
> -	GEM_BUG_ON(!context_wait_for_deregister_to_register(ce));
> -
>   	spin_lock_irqsave(&ce->guc_state.lock, flags);
>   	clr_context_wait_for_deregister_to_register(ce);
>   	__guc_signal_context_fence(ce);
> @@ -1193,8 +1559,9 @@ static void guc_signal_context_fence(struct intel_context *ce)
>   
>   static bool context_needs_register(struct intel_context *ce, bool new_guc_id)
>   {
> -	return new_guc_id || test_bit(CONTEXT_LRCA_DIRTY, &ce->flags) ||
> -		!lrc_desc_registered(ce_to_guc(ce), ce->guc_id);
> +	return (new_guc_id || test_bit(CONTEXT_LRCA_DIRTY, &ce->flags) ||
> +		!lrc_desc_registered(ce_to_guc(ce), ce->guc_id)) &&
> +		!submission_disabled(ce_to_guc(ce));
>   }
>   
>   static int guc_request_alloc(struct i915_request *rq)
> @@ -1252,8 +1619,12 @@ static int guc_request_alloc(struct i915_request *rq)
>   	if (unlikely(ret < 0))
>   		return ret;;
>   	if (context_needs_register(ce, !!ret)) {
> -		ret = guc_lrc_desc_pin(ce);
> +		ret = guc_lrc_desc_pin(ce, true);
>   		if (unlikely(ret)) {	/* unwind */
> +			if (ret == -EIO) {
> +				disable_submission(guc);
> +				goto out;	/* GPU will be reset */
> +			}
>   			atomic_dec(&ce->guc_id_ref);
>   			unpin_guc_id(guc, ce);
>   			return ret;
> @@ -1290,20 +1661,6 @@ static int guc_request_alloc(struct i915_request *rq)
>   	return 0;
>   }
>   
> -static struct intel_engine_cs *
> -guc_virtual_get_sibling(struct intel_engine_cs *ve, unsigned int sibling)
> -{
> -	struct intel_engine_cs *engine;
> -	intel_engine_mask_t tmp, mask = ve->mask;
> -	unsigned int num_siblings = 0;
> -
> -	for_each_engine_masked(engine, ve->gt, mask, tmp)
> -		if (num_siblings++ == sibling)
> -			return engine;
> -
> -	return NULL;
> -}
> -
>   static int guc_virtual_context_pre_pin(struct intel_context *ce,
>   				       struct i915_gem_ww_ctx *ww,
>   				       void **vaddr)
> @@ -1512,7 +1869,7 @@ static inline void guc_kernel_context_pin(struct intel_guc *guc,
>   {
>   	if (context_guc_id_invalid(ce))
>   		pin_guc_id(guc, ce);
> -	guc_lrc_desc_pin(ce);
> +	guc_lrc_desc_pin(ce, true);
>   }
>   
>   static inline void guc_init_lrc_mapping(struct intel_guc *guc)
> @@ -1578,13 +1935,15 @@ static void guc_default_vfuncs(struct intel_engine_cs *engine)
>   	engine->cops = &guc_context_ops;
>   	engine->request_alloc = guc_request_alloc;
>   	engine->bump_serial = guc_bump_serial;
> +	engine->add_active_request = add_to_context;
> +	engine->remove_active_request = remove_from_context;
>   
>   	engine->sched_engine->schedule = i915_schedule;
>   
> -	engine->reset.prepare = guc_reset_prepare;
> -	engine->reset.rewind = guc_reset_rewind;
> -	engine->reset.cancel = guc_reset_cancel;
> -	engine->reset.finish = guc_reset_finish;
> +	engine->reset.prepare = guc_reset_nop;
> +	engine->reset.rewind = guc_rewind_nop;
> +	engine->reset.cancel = guc_reset_nop;
> +	engine->reset.finish = guc_reset_nop;
>   
>   	engine->emit_flush = gen8_emit_flush_xcs;
>   	engine->emit_init_breadcrumb = gen8_emit_init_breadcrumb;
> @@ -1757,7 +2116,7 @@ int intel_guc_deregister_done_process_msg(struct intel_guc *guc,
>   		 * register this context.
>   		 */
>   		with_intel_runtime_pm(runtime_pm, wakeref)
> -			register_context(ce);
> +			register_context(ce, true);
>   		guc_signal_context_fence(ce);
>   		intel_context_put(ce);
>   	} else if (context_destroyed(ce)) {
> @@ -1939,6 +2298,10 @@ guc_create_virtual(struct intel_engine_cs **siblings, unsigned int count)
>   				 "v%dx%d", ve->base.class, count);
>   			ve->base.context_size = sibling->context_size;
>   
> +			ve->base.add_active_request =
> +				sibling->add_active_request;
> +			ve->base.remove_active_request =
> +				sibling->remove_active_request;
>   			ve->base.emit_bb_start = sibling->emit_bb_start;
>   			ve->base.emit_flush = sibling->emit_flush;
>   			ve->base.emit_init_breadcrumb =
> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_uc.c b/drivers/gpu/drm/i915/gt/uc/intel_uc.c
> index 6d8b9233214e..f0b02200aa01 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_uc.c
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_uc.c
> @@ -565,12 +565,49 @@ void intel_uc_reset_prepare(struct intel_uc *uc)
>   {
>   	struct intel_guc *guc = &uc->guc;
>   
> -	if (!intel_guc_is_ready(guc))
> +
> +	/* Nothing to do if GuC isn't supported */
> +	if (!intel_uc_supports_guc(uc))
>   		return;
>   
> +	/* Firmware expected to be running when this function is called */
> +	if (!intel_guc_is_ready(guc))
> +		goto sanitize;
> +
> +	if (intel_uc_uses_guc_submission(uc))
> +		intel_guc_submission_reset_prepare(guc);
> +
> +sanitize:
>   	__uc_sanitize(uc);
>   }
>   
> +void intel_uc_reset(struct intel_uc *uc, bool stalled)
> +{
> +	struct intel_guc *guc = &uc->guc;
> +
> +	/* Firmware can not be running when this function is called  */
> +	if (intel_uc_uses_guc_submission(uc))
> +		intel_guc_submission_reset(guc, stalled);
> +}
> +
> +void intel_uc_reset_finish(struct intel_uc *uc)
> +{
> +	struct intel_guc *guc = &uc->guc;
> +
> +	/* Firmware expected to be running when this function is called */
> +	if (intel_guc_is_fw_running(guc) && intel_uc_uses_guc_submission(uc))
> +		intel_guc_submission_reset_finish(guc);
> +}
> +
> +void intel_uc_cancel_requests(struct intel_uc *uc)
> +{
> +	struct intel_guc *guc = &uc->guc;
> +
> +	/* Firmware can not be running when this function is called  */
> +	if (intel_uc_uses_guc_submission(uc))
> +		intel_guc_submission_cancel_requests(guc);
> +}
> +
>   void intel_uc_runtime_suspend(struct intel_uc *uc)
>   {
>   	struct intel_guc *guc = &uc->guc;
> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_uc.h b/drivers/gpu/drm/i915/gt/uc/intel_uc.h
> index c4cef885e984..eaa3202192ac 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_uc.h
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_uc.h
> @@ -37,6 +37,9 @@ void intel_uc_driver_late_release(struct intel_uc *uc);
>   void intel_uc_driver_remove(struct intel_uc *uc);
>   void intel_uc_init_mmio(struct intel_uc *uc);
>   void intel_uc_reset_prepare(struct intel_uc *uc);
> +void intel_uc_reset(struct intel_uc *uc, bool stalled);
> +void intel_uc_reset_finish(struct intel_uc *uc);
> +void intel_uc_cancel_requests(struct intel_uc *uc);
>   void intel_uc_suspend(struct intel_uc *uc);
>   void intel_uc_runtime_suspend(struct intel_uc *uc);
>   int intel_uc_resume(struct intel_uc *uc);
> diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
> index dec5a35c9aa2..192784875a1d 100644
> --- a/drivers/gpu/drm/i915/i915_request.c
> +++ b/drivers/gpu/drm/i915/i915_request.c
> @@ -194,7 +194,7 @@ static bool irq_work_imm(struct irq_work *wrk)
>   	return false;
>   }
>   
> -static void __notify_execute_cb_imm(struct i915_request *rq)
> +void i915_request_notify_execute_cb_imm(struct i915_request *rq)
>   {
>   	__notify_execute_cb(rq, irq_work_imm);
>   }
> @@ -268,37 +268,6 @@ i915_request_active_engine(struct i915_request *rq,
>   	return ret;
>   }
>   
> -
> -static void remove_from_engine(struct i915_request *rq)
> -{
> -	struct intel_engine_cs *engine, *locked;
> -
> -	/*
> -	 * Virtual engines complicate acquiring the engine timeline lock,
> -	 * as their rq->engine pointer is not stable until under that
> -	 * engine lock. The simple ploy we use is to take the lock then
> -	 * check that the rq still belongs to the newly locked engine.
> -	 */
> -	locked = READ_ONCE(rq->engine);
> -	spin_lock_irq(&locked->sched_engine->lock);
> -	while (unlikely(locked != (engine = READ_ONCE(rq->engine)))) {
> -		spin_unlock(&locked->sched_engine->lock);
> -		spin_lock(&engine->sched_engine->lock);
> -		locked = engine;
> -	}
> -	list_del_init(&rq->sched.link);
> -
> -	clear_bit(I915_FENCE_FLAG_PQUEUE, &rq->fence.flags);
> -	clear_bit(I915_FENCE_FLAG_HOLD, &rq->fence.flags);
> -
> -	/* Prevent further __await_execution() registering a cb, then flush */
> -	set_bit(I915_FENCE_FLAG_ACTIVE, &rq->fence.flags);
> -
> -	spin_unlock_irq(&locked->sched_engine->lock);
> -
> -	__notify_execute_cb_imm(rq);
> -}
> -
>   static void __rq_init_watchdog(struct i915_request *rq)
>   {
>   	rq->watchdog.timer.function = NULL;
> @@ -395,9 +364,7 @@ bool i915_request_retire(struct i915_request *rq)
>   	 * after removing the breadcrumb and signaling it, so that we do not
>   	 * inadvertently attach the breadcrumb to a completed request.
>   	 */
> -	if (!list_empty(&rq->sched.link))
> -		remove_from_engine(rq);
> -	atomic_dec(&rq->context->guc_id_ref);
> +	rq->engine->remove_active_request(rq);
>   	GEM_BUG_ON(!llist_empty(&rq->execute_cb));
>   
>   	__list_del_entry(&rq->link); /* poison neither prev/next (RCU walks) */
> @@ -539,7 +506,7 @@ __await_execution(struct i915_request *rq,
>   	if (llist_add(&cb->work.node.llist, &signal->execute_cb)) {
>   		if (i915_request_is_active(signal) ||
>   		    __request_in_flight(signal))
> -			__notify_execute_cb_imm(signal);
> +			i915_request_notify_execute_cb_imm(signal);
>   	}
>   
>   	return 0;
> @@ -676,7 +643,7 @@ bool __i915_request_submit(struct i915_request *request)
>   	result = true;
>   
>   	GEM_BUG_ON(test_bit(I915_FENCE_FLAG_ACTIVE, &request->fence.flags));
> -	list_move_tail(&request->sched.link, &engine->sched_engine->requests);
> +	engine->add_active_request(request);
>   active:
>   	clear_bit(I915_FENCE_FLAG_PQUEUE, &request->fence.flags);
>   	set_bit(I915_FENCE_FLAG_ACTIVE, &request->fence.flags);
> diff --git a/drivers/gpu/drm/i915/i915_request.h b/drivers/gpu/drm/i915/i915_request.h
> index f870cd75a001..bcc6340c505e 100644
> --- a/drivers/gpu/drm/i915/i915_request.h
> +++ b/drivers/gpu/drm/i915/i915_request.h
> @@ -649,4 +649,6 @@ bool
>   i915_request_active_engine(struct i915_request *rq,
>   			   struct intel_engine_cs **active);
>   
> +void i915_request_notify_execute_cb_imm(struct i915_request *rq);
> +
>   #endif /* I915_REQUEST_H */
>

Matthew Brost July 26, 2021, 10:48 p.m. UTC | #4

On Thu, Jul 15, 2021 at 10:36:51AM +0100, Tvrtko Ursulin wrote:
> 
> On 24/06/2021 08:05, Matthew Brost wrote:
> > Reset implementation for new GuC interface. This is the legacy reset
> > implementation which is called when the i915 owns the engine hang check.
> > Future patches will offload the engine hang check to GuC but we will
> > continue to maintain this legacy path as a fallback and this code path
> > is also required if the GuC dies.
> > 
> > With the new GuC interface it is not possible to reset individual
> > engines - it is only possible to reset the GPU entirely. This patch
> > forces an entire chip reset if any engine hangs.
> 
> No updates after my review comments on 6th of May.
> 
> At least:
> 
> 1. wmb documentation
> 

Yea, missed this. Checkpatch yelled at me too. Will be fixed in next
rev.

> 2. Spin lock cycling I either didn't understand or didn't buy the
> explanation. I don't remember seeing that pattern elsewhere in the driver -
> cycle a spinlock to make sure what was updated inside it is visible you
> said?
>

I did respond - not really my fault if you don't understand a fairly
simple concept but I'll explain again.

Change a variable
Cycle a lock
At this point we know anyone that acquires above lock the variable
change is visible.

I can't be the first person in the Linux kernel to do this nor in the
i915.

This basically allows to seal all the reset races without a BKL.

Also I told you I explain in this a doc patch that will get reposted
after GuC submission lands:
https://patchwork.freedesktop.org/patch/432408/?series=89844&rev=1

> 3. Dropping the lock protecting the list in the middle of
> list_for_each_entry_safe and just continuing to iterate like nothing
> happened. (__unwind_incomplete_requests) Again, perhaps I did not understand
> your explanation properly but you did appear to write:
>

To be honest looking at the code now we likely don't need to drop the
look but regardless I don't think we should change this for the
following reasons.

1. I assure you this is safe and works. I can add a better comment
explaining this though.
2. This is thoroughly tested and resets are the hardest thing to get
stable and working.
3. This code is literally going to get deleted when we move to the DRM
scheduler as all the tracking / unwinding / resubmission will be in the
DRM scheduler core.
4. A 2 second search of the driver found that we do the same thing in
intel_gt_retire_requests_timeout so this isn't unprecedented.

Matt

> """
> We only need the active lock for ce->guc_active.requests list. It is
> indeed safe to drop the lock.
> """
> 
> +	spin_lock(&ce->guc_active.lock);
> +	list_for_each_entry_safe(rq, rn,
> +				 &ce->guc_active.requests,
> +				 sched.link) {
> +		if (i915_request_completed(rq))
> +			continue;
> +
> +		list_del_init(&rq->sched.link);
> +		spin_unlock(&ce->guc_active.lock);
> ...
> +		spin_lock(&ce->guc_active.lock);
> +	}
> 
> Safe iterator guards against list_del but dropping the lock means the state
> of the overall list can change so next pointer may or may not be valid,
> requests may be missed, I don't know. Needs a comment explaining why it is
> safe.
> 
> Regards,
> 
> Tvrtko
> 
> > 
> > Cc: John Harrison <[e-mail]>
> > Signed-off-by: Matthew Brost <[e-mail]>
> > ---
> >   drivers/gpu/drm/i915/gt/intel_context.c       |   3 +
> >   drivers/gpu/drm/i915/gt/intel_context_types.h |   7 +
> >   drivers/gpu/drm/i915/gt/intel_engine_types.h  |   6 +
> >   .../drm/i915/gt/intel_execlists_submission.c  |  40 ++
> >   drivers/gpu/drm/i915/gt/intel_gt_pm.c         |   6 +-
> >   drivers/gpu/drm/i915/gt/intel_reset.c         |  18 +-
> >   .../gpu/drm/i915/gt/intel_ring_submission.c   |  22 +
> >   drivers/gpu/drm/i915/gt/mock_engine.c         |  31 +
> >   drivers/gpu/drm/i915/gt/uc/intel_guc.c        |  13 -
> >   drivers/gpu/drm/i915/gt/uc/intel_guc.h        |   8 +-
> >   .../gpu/drm/i915/gt/uc/intel_guc_submission.c | 581 ++++++++++++++----
> >   drivers/gpu/drm/i915/gt/uc/intel_uc.c         |  39 +-
> >   drivers/gpu/drm/i915/gt/uc/intel_uc.h         |   3 +
> >   drivers/gpu/drm/i915/i915_request.c           |  41 +-
> >   drivers/gpu/drm/i915/i915_request.h           |   2 +
> >   15 files changed, 649 insertions(+), 171 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/gt/intel_context.c b/drivers/gpu/drm/i915/gt/intel_context.c
> > index b24a1b7a3f88..2f01437056a8 100644
> > --- a/drivers/gpu/drm/i915/gt/intel_context.c
> > +++ b/drivers/gpu/drm/i915/gt/intel_context.c
> > @@ -392,6 +392,9 @@ intel_context_init(struct intel_context *ce, struct intel_engine_cs *engine)
> >   	spin_lock_init(&ce->guc_state.lock);
> >   	INIT_LIST_HEAD(&ce->guc_state.fences);
> > +	spin_lock_init(&ce->guc_active.lock);
> > +	INIT_LIST_HEAD(&ce->guc_active.requests);
> > +
> >   	ce->guc_id = GUC_INVALID_LRC_ID;
> >   	INIT_LIST_HEAD(&ce->guc_id_link);
> > diff --git a/drivers/gpu/drm/i915/gt/intel_context_types.h b/drivers/gpu/drm/i915/gt/intel_context_types.h
> > index 6945963a31ba..b63c8cf7823b 100644
> > --- a/drivers/gpu/drm/i915/gt/intel_context_types.h
> > +++ b/drivers/gpu/drm/i915/gt/intel_context_types.h
> > @@ -165,6 +165,13 @@ struct intel_context {
> >   		struct list_head fences;
> >   	} guc_state;
> > +	struct {
> > +		/** lock: protects everything in guc_active */
> > +		spinlock_t lock;
> > +		/** requests: active requests on this context */
> > +		struct list_head requests;
> > +	} guc_active;
> > +
> >   	/* GuC scheduling state that does not require a lock. */
> >   	atomic_t guc_sched_state_no_lock;
> > diff --git a/drivers/gpu/drm/i915/gt/intel_engine_types.h b/drivers/gpu/drm/i915/gt/intel_engine_types.h
> > index e7cb6a06db9d..f9d264c008e8 100644
> > --- a/drivers/gpu/drm/i915/gt/intel_engine_types.h
> > +++ b/drivers/gpu/drm/i915/gt/intel_engine_types.h
> > @@ -426,6 +426,12 @@ struct intel_engine_cs {
> >   	void		(*release)(struct intel_engine_cs *engine);
> > +	/*
> > +	 * Add / remove request from engine active tracking
> > +	 */
> > +	void		(*add_active_request)(struct i915_request *rq);
> > +	void		(*remove_active_request)(struct i915_request *rq);
> > +
> >   	struct intel_engine_execlists execlists;
> >   	/*
> > diff --git a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
> > index c10ea6080752..c301a2d088b1 100644
> > --- a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
> > +++ b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
> > @@ -3118,6 +3118,42 @@ static void execlists_park(struct intel_engine_cs *engine)
> >   	cancel_timer(&engine->execlists.preempt);
> >   }
> > +static void add_to_engine(struct i915_request *rq)
> > +{
> > +	lockdep_assert_held(&rq->engine->sched_engine->lock);
> > +	list_move_tail(&rq->sched.link, &rq->engine->sched_engine->requests);
> > +}
> > +
> > +static void remove_from_engine(struct i915_request *rq)
> > +{
> > +	struct intel_engine_cs *engine, *locked;
> > +
> > +	/*
> > +	 * Virtual engines complicate acquiring the engine timeline lock,
> > +	 * as their rq->engine pointer is not stable until under that
> > +	 * engine lock. The simple ploy we use is to take the lock then
> > +	 * check that the rq still belongs to the newly locked engine.
> > +	 */
> > +	locked = READ_ONCE(rq->engine);
> > +	spin_lock_irq(&locked->sched_engine->lock);
> > +	while (unlikely(locked != (engine = READ_ONCE(rq->engine)))) {
> > +		spin_unlock(&locked->sched_engine->lock);
> > +		spin_lock(&engine->sched_engine->lock);
> > +		locked = engine;
> > +	}
> > +	list_del_init(&rq->sched.link);
> > +
> > +	clear_bit(I915_FENCE_FLAG_PQUEUE, &rq->fence.flags);
> > +	clear_bit(I915_FENCE_FLAG_HOLD, &rq->fence.flags);
> > +
> > +	/* Prevent further __await_execution() registering a cb, then flush */
> > +	set_bit(I915_FENCE_FLAG_ACTIVE, &rq->fence.flags);
> > +
> > +	spin_unlock_irq(&locked->sched_engine->lock);
> > +
> > +	i915_request_notify_execute_cb_imm(rq);
> > +}
> > +
> >   static bool can_preempt(struct intel_engine_cs *engine)
> >   {
> >   	if (GRAPHICS_VER(engine->i915) > 8)
> > @@ -3218,6 +3254,8 @@ logical_ring_default_vfuncs(struct intel_engine_cs *engine)
> >   	engine->cops = &execlists_context_ops;
> >   	engine->request_alloc = execlists_request_alloc;
> >   	engine->bump_serial = execlist_bump_serial;
> > +	engine->add_active_request = add_to_engine;
> > +	engine->remove_active_request = remove_from_engine;
> >   	engine->reset.prepare = execlists_reset_prepare;
> >   	engine->reset.rewind = execlists_reset_rewind;
> > @@ -3912,6 +3950,8 @@ execlists_create_virtual(struct intel_engine_cs **siblings, unsigned int count)
> >   			 "v%dx%d", ve->base.class, count);
> >   		ve->base.context_size = sibling->context_size;
> > +		ve->base.add_active_request = sibling->add_active_request;
> > +		ve->base.remove_active_request = sibling->remove_active_request;
> >   		ve->base.emit_bb_start = sibling->emit_bb_start;
> >   		ve->base.emit_flush = sibling->emit_flush;
> >   		ve->base.emit_init_breadcrumb = sibling->emit_init_breadcrumb;
> > diff --git a/drivers/gpu/drm/i915/gt/intel_gt_pm.c b/drivers/gpu/drm/i915/gt/intel_gt_pm.c
> > index aef3084e8b16..463a6ae605a0 100644
> > --- a/drivers/gpu/drm/i915/gt/intel_gt_pm.c
> > +++ b/drivers/gpu/drm/i915/gt/intel_gt_pm.c
> > @@ -174,8 +174,6 @@ static void gt_sanitize(struct intel_gt *gt, bool force)
> >   	if (intel_gt_is_wedged(gt))
> >   		intel_gt_unset_wedged(gt);
> > -	intel_uc_sanitize(&gt->uc);
> > -
> >   	for_each_engine(engine, gt, id)
> >   		if (engine->reset.prepare)
> >   			engine->reset.prepare(engine);
> > @@ -191,6 +189,8 @@ static void gt_sanitize(struct intel_gt *gt, bool force)
> >   			__intel_engine_reset(engine, false);
> >   	}
> > +	intel_uc_reset(&gt->uc, false);
> > +
> >   	for_each_engine(engine, gt, id)
> >   		if (engine->reset.finish)
> >   			engine->reset.finish(engine);
> > @@ -243,6 +243,8 @@ int intel_gt_resume(struct intel_gt *gt)
> >   		goto err_wedged;
> >   	}
> > +	intel_uc_reset_finish(&gt->uc);
> > +
> >   	intel_rps_enable(&gt->rps);
> >   	intel_llc_enable(&gt->llc);
> > diff --git a/drivers/gpu/drm/i915/gt/intel_reset.c b/drivers/gpu/drm/i915/gt/intel_reset.c
> > index 72251638d4ea..2987282dff6d 100644
> > --- a/drivers/gpu/drm/i915/gt/intel_reset.c
> > +++ b/drivers/gpu/drm/i915/gt/intel_reset.c
> > @@ -826,6 +826,8 @@ static int gt_reset(struct intel_gt *gt, intel_engine_mask_t stalled_mask)
> >   		__intel_engine_reset(engine, stalled_mask & engine->mask);
> >   	local_bh_enable();
> > +	intel_uc_reset(&gt->uc, true);
> > +
> >   	intel_ggtt_restore_fences(gt->ggtt);
> >   	return err;
> > @@ -850,6 +852,8 @@ static void reset_finish(struct intel_gt *gt, intel_engine_mask_t awake)
> >   		if (awake & engine->mask)
> >   			intel_engine_pm_put(engine);
> >   	}
> > +
> > +	intel_uc_reset_finish(&gt->uc);
> >   }
> >   static void nop_submit_request(struct i915_request *request)
> > @@ -903,6 +907,7 @@ static void __intel_gt_set_wedged(struct intel_gt *gt)
> >   	for_each_engine(engine, gt, id)
> >   		if (engine->reset.cancel)
> >   			engine->reset.cancel(engine);
> > +	intel_uc_cancel_requests(&gt->uc);
> >   	local_bh_enable();
> >   	reset_finish(gt, awake);
> > @@ -1191,6 +1196,9 @@ int __intel_engine_reset_bh(struct intel_engine_cs *engine, const char *msg)
> >   	ENGINE_TRACE(engine, "flags=%lx\n", gt->reset.flags);
> >   	GEM_BUG_ON(!test_bit(I915_RESET_ENGINE + engine->id, &gt->reset.flags));
> > +	if (intel_engine_uses_guc(engine))
> > +		return -ENODEV;
> > +
> >   	if (!intel_engine_pm_get_if_awake(engine))
> >   		return 0;
> > @@ -1201,13 +1209,10 @@ int __intel_engine_reset_bh(struct intel_engine_cs *engine, const char *msg)
> >   			   "Resetting %s for %s\n", engine->name, msg);
> >   	atomic_inc(&engine->i915->gpu_error.reset_engine_count[engine->uabi_class]);
> > -	if (intel_engine_uses_guc(engine))
> > -		ret = intel_guc_reset_engine(&engine->gt->uc.guc, engine);
> > -	else
> > -		ret = intel_gt_reset_engine(engine);
> > +	ret = intel_gt_reset_engine(engine);
> >   	if (ret) {
> >   		/* If we fail here, we expect to fallback to a global reset */
> > -		ENGINE_TRACE(engine, "Failed to reset, err: %d\n", ret);
> > +		ENGINE_TRACE(engine, "Failed to reset %s, err: %d\n", engine->name, ret);
> >   		goto out;
> >   	}
> > @@ -1341,7 +1346,8 @@ void intel_gt_handle_error(struct intel_gt *gt,
> >   	 * Try engine reset when available. We fall back to full reset if
> >   	 * single reset fails.
> >   	 */
> > -	if (intel_has_reset_engine(gt) && !intel_gt_is_wedged(gt)) {
> > +	if (!intel_uc_uses_guc_submission(&gt->uc) &&
> > +	    intel_has_reset_engine(gt) && !intel_gt_is_wedged(gt)) {
> >   		local_bh_disable();
> >   		for_each_engine_masked(engine, gt, engine_mask, tmp) {
> >   			BUILD_BUG_ON(I915_RESET_MODESET >= I915_RESET_ENGINE);
> > diff --git a/drivers/gpu/drm/i915/gt/intel_ring_submission.c b/drivers/gpu/drm/i915/gt/intel_ring_submission.c
> > index e1506b280df1..99dcdc8fba12 100644
> > --- a/drivers/gpu/drm/i915/gt/intel_ring_submission.c
> > +++ b/drivers/gpu/drm/i915/gt/intel_ring_submission.c
> > @@ -1049,6 +1049,25 @@ static void ring_bump_serial(struct intel_engine_cs *engine)
> >   	engine->serial++;
> >   }
> > +static void add_to_engine(struct i915_request *rq)
> > +{
> > +	lockdep_assert_held(&rq->engine->sched_engine->lock);
> > +	list_move_tail(&rq->sched.link, &rq->engine->sched_engine->requests);
> > +}
> > +
> > +static void remove_from_engine(struct i915_request *rq)
> > +{
> > +	spin_lock_irq(&rq->engine->sched_engine->lock);
> > +	list_del_init(&rq->sched.link);
> > +
> > +	/* Prevent further __await_execution() registering a cb, then flush */
> > +	set_bit(I915_FENCE_FLAG_ACTIVE, &rq->fence.flags);
> > +
> > +	spin_unlock_irq(&rq->engine->sched_engine->lock);
> > +
> > +	i915_request_notify_execute_cb_imm(rq);
> > +}
> > +
> >   static void setup_common(struct intel_engine_cs *engine)
> >   {
> >   	struct drm_i915_private *i915 = engine->i915;
> > @@ -1066,6 +1085,9 @@ static void setup_common(struct intel_engine_cs *engine)
> >   	engine->reset.cancel = reset_cancel;
> >   	engine->reset.finish = reset_finish;
> > +	engine->add_active_request = add_to_engine;
> > +	engine->remove_active_request = remove_from_engine;
> > +
> >   	engine->cops = &ring_context_ops;
> >   	engine->request_alloc = ring_request_alloc;
> >   	engine->bump_serial = ring_bump_serial;
> > diff --git a/drivers/gpu/drm/i915/gt/mock_engine.c b/drivers/gpu/drm/i915/gt/mock_engine.c
> > index fc5a65ab1937..c12ff3a75ce6 100644
> > --- a/drivers/gpu/drm/i915/gt/mock_engine.c
> > +++ b/drivers/gpu/drm/i915/gt/mock_engine.c
> > @@ -235,6 +235,35 @@ static void mock_submit_request(struct i915_request *request)
> >   	spin_unlock_irqrestore(&engine->hw_lock, flags);
> >   }
> > +static void mock_add_to_engine(struct i915_request *rq)
> > +{
> > +	lockdep_assert_held(&rq->engine->sched_engine->lock);
> > +	list_move_tail(&rq->sched.link, &rq->engine->sched_engine->requests);
> > +}
> > +
> > +static void mock_remove_from_engine(struct i915_request *rq)
> > +{
> > +	struct intel_engine_cs *engine, *locked;
> > +
> > +	/*
> > +	 * Virtual engines complicate acquiring the engine timeline lock,
> > +	 * as their rq->engine pointer is not stable until under that
> > +	 * engine lock. The simple ploy we use is to take the lock then
> > +	 * check that the rq still belongs to the newly locked engine.
> > +	 */
> > +
> > +	locked = READ_ONCE(rq->engine);
> > +	spin_lock_irq(&locked->sched_engine->lock);
> > +	while (unlikely(locked != (engine = READ_ONCE(rq->engine)))) {
> > +		spin_unlock(&locked->sched_engine->lock);
> > +		spin_lock(&engine->sched_engine->lock);
> > +		locked = engine;
> > +	}
> > +	list_del_init(&rq->sched.link);
> > +	spin_unlock_irq(&locked->sched_engine->lock);
> > +}
> > +
> > +
> >   static void mock_reset_prepare(struct intel_engine_cs *engine)
> >   {
> >   }
> > @@ -327,6 +356,8 @@ struct intel_engine_cs *mock_engine(struct drm_i915_private *i915,
> >   	engine->base.emit_flush = mock_emit_flush;
> >   	engine->base.emit_fini_breadcrumb = mock_emit_breadcrumb;
> >   	engine->base.submit_request = mock_submit_request;
> > +	engine->base.add_active_request = mock_add_to_engine;
> > +	engine->base.remove_active_request = mock_remove_from_engine;
> >   	engine->base.reset.prepare = mock_reset_prepare;
> >   	engine->base.reset.rewind = mock_reset_rewind;
> > diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc.c b/drivers/gpu/drm/i915/gt/uc/intel_guc.c
> > index 6661dcb02239..9b09395b998f 100644
> > --- a/drivers/gpu/drm/i915/gt/uc/intel_guc.c
> > +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc.c
> > @@ -572,19 +572,6 @@ int intel_guc_suspend(struct intel_guc *guc)
> >   	return 0;
> >   }
> > -/**
> > - * intel_guc_reset_engine() - ask GuC to reset an engine
> > - * @guc:	intel_guc structure
> > - * @engine:	engine to be reset
> > - */
> > -int intel_guc_reset_engine(struct intel_guc *guc,
> > -			   struct intel_engine_cs *engine)
> > -{
> > -	/* XXX: to be implemented with submission interface rework */
> > -
> > -	return -ENODEV;
> > -}
> > -
> >   /**
> >    * intel_guc_resume() - notify GuC resuming from suspend state
> >    * @guc:	the guc
> > diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc.h b/drivers/gpu/drm/i915/gt/uc/intel_guc.h
> > index 22eb1e9cca41..40c9868762d7 100644
> > --- a/drivers/gpu/drm/i915/gt/uc/intel_guc.h
> > +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc.h
> > @@ -242,14 +242,16 @@ static inline void intel_guc_disable_msg(struct intel_guc *guc, u32 mask)
> >   int intel_guc_wait_for_idle(struct intel_guc *guc, long timeout);
> > -int intel_guc_reset_engine(struct intel_guc *guc,
> > -			   struct intel_engine_cs *engine);
> > -
> >   int intel_guc_deregister_done_process_msg(struct intel_guc *guc,
> >   					  const u32 *msg, u32 len);
> >   int intel_guc_sched_done_process_msg(struct intel_guc *guc,
> >   				     const u32 *msg, u32 len);
> > +void intel_guc_submission_reset_prepare(struct intel_guc *guc);
> > +void intel_guc_submission_reset(struct intel_guc *guc, bool stalled);
> > +void intel_guc_submission_reset_finish(struct intel_guc *guc);
> > +void intel_guc_submission_cancel_requests(struct intel_guc *guc);
> > +
> >   void intel_guc_load_status(struct intel_guc *guc, struct drm_printer *p);
> >   #endif
> > diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> > index 83058df5ba01..b8c894ad8caf 100644
> > --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> > +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> > @@ -141,7 +141,7 @@ context_wait_for_deregister_to_register(struct intel_context *ce)
> >   static inline void
> >   set_context_wait_for_deregister_to_register(struct intel_context *ce)
> >   {
> > -	/* Only should be called from guc_lrc_desc_pin() */
> > +	/* Only should be called from guc_lrc_desc_pin() without lock */
> >   	ce->guc_state.sched_state |=
> >   		SCHED_STATE_WAIT_FOR_DEREGISTER_TO_REGISTER;
> >   }
> > @@ -241,15 +241,31 @@ static int guc_lrc_desc_pool_create(struct intel_guc *guc)
> >   static void guc_lrc_desc_pool_destroy(struct intel_guc *guc)
> >   {
> > +	guc->lrc_desc_pool_vaddr = NULL;
> >   	i915_vma_unpin_and_release(&guc->lrc_desc_pool, I915_VMA_RELEASE_MAP);
> >   }
> > +static inline bool guc_submission_initialized(struct intel_guc *guc)
> > +{
> > +	return guc->lrc_desc_pool_vaddr != NULL;
> > +}
> > +
> >   static inline void reset_lrc_desc(struct intel_guc *guc, u32 id)
> >   {
> > -	struct guc_lrc_desc *desc = __get_lrc_desc(guc, id);
> > +	if (likely(guc_submission_initialized(guc))) {
> > +		struct guc_lrc_desc *desc = __get_lrc_desc(guc, id);
> > +		unsigned long flags;
> > -	memset(desc, 0, sizeof(*desc));
> > -	xa_erase_irq(&guc->context_lookup, id);
> > +		memset(desc, 0, sizeof(*desc));
> > +
> > +		/*
> > +		 * xarray API doesn't have xa_erase_irqsave wrapper, so calling
> > +		 * the lower level functions directly.
> > +		 */
> > +		xa_lock_irqsave(&guc->context_lookup, flags);
> > +		__xa_erase(&guc->context_lookup, id);
> > +		xa_unlock_irqrestore(&guc->context_lookup, flags);
> > +	}
> >   }
> >   static inline bool lrc_desc_registered(struct intel_guc *guc, u32 id)
> > @@ -260,7 +276,15 @@ static inline bool lrc_desc_registered(struct intel_guc *guc, u32 id)
> >   static inline void set_lrc_desc_registered(struct intel_guc *guc, u32 id,
> >   					   struct intel_context *ce)
> >   {
> > -	xa_store_irq(&guc->context_lookup, id, ce, GFP_ATOMIC);
> > +	unsigned long flags;
> > +
> > +	/*
> > +	 * xarray API doesn't have xa_save_irqsave wrapper, so calling the
> > +	 * lower level functions directly.
> > +	 */
> > +	xa_lock_irqsave(&guc->context_lookup, flags);
> > +	__xa_store(&guc->context_lookup, id, ce, GFP_ATOMIC);
> > +	xa_unlock_irqrestore(&guc->context_lookup, flags);
> >   }
> >   static int guc_submission_busy_loop(struct intel_guc* guc,
> > @@ -331,6 +355,8 @@ int intel_guc_wait_for_idle(struct intel_guc *guc, long timeout)
> >   					interruptible, timeout);
> >   }
> > +static int guc_lrc_desc_pin(struct intel_context *ce, bool loop);
> > +
> >   static int guc_add_request(struct intel_guc *guc, struct i915_request *rq)
> >   {
> >   	int err;
> > @@ -338,11 +364,22 @@ static int guc_add_request(struct intel_guc *guc, struct i915_request *rq)
> >   	u32 action[3];
> >   	int len = 0;
> >   	u32 g2h_len_dw = 0;
> > -	bool enabled = context_enabled(ce);
> > +	bool enabled;
> >   	GEM_BUG_ON(!atomic_read(&ce->guc_id_ref));
> >   	GEM_BUG_ON(context_guc_id_invalid(ce));
> > +	/*
> > +	 * Corner case where the GuC firmware was blown away and reloaded while
> > +	 * this context was pinned.
> > +	 */
> > +	if (unlikely(!lrc_desc_registered(guc, ce->guc_id))) {
> > +		err = guc_lrc_desc_pin(ce, false);
> > +		if (unlikely(err))
> > +			goto out;
> > +	}
> > +	enabled = context_enabled(ce);
> > +
> >   	if (!enabled) {
> >   		action[len++] = INTEL_GUC_ACTION_SCHED_CONTEXT_MODE_SET;
> >   		action[len++] = ce->guc_id;
> > @@ -365,6 +402,7 @@ static int guc_add_request(struct intel_guc *guc, struct i915_request *rq)
> >   		intel_context_put(ce);
> >   	}
> > +out:
> >   	return err;
> >   }
> > @@ -419,15 +457,10 @@ static int guc_dequeue_one_context(struct intel_guc *guc)
> >   	if (submit) {
> >   		guc_set_lrc_tail(last);
> >   resubmit:
> > -		/*
> > -		 * We only check for -EBUSY here even though it is possible for
> > -		 * -EDEADLK to be returned. If -EDEADLK is returned, the GuC has
> > -		 * died and a full GPU needs to be done. The hangcheck will
> > -		 * eventually detect that the GuC has died and trigger this
> > -		 * reset so no need to handle -EDEADLK here.
> > -		 */
> >   		ret = guc_add_request(guc, last);
> > -		if (ret == -EBUSY) {
> > +		if (unlikely(ret == -EIO))
> > +			goto deadlk;
> > +		else if (ret == -EBUSY) {
> >   			tasklet_schedule(&sched_engine->tasklet);
> >   			guc->stalled_request = last;
> >   			return false;
> > @@ -437,6 +470,11 @@ static int guc_dequeue_one_context(struct intel_guc *guc)
> >   	guc->stalled_request = NULL;
> >   	return submit;
> > +
> > +deadlk:
> > +	sched_engine->tasklet.callback = NULL;
> > +	tasklet_disable_nosync(&sched_engine->tasklet);
> > +	return false;
> >   }
> >   static void guc_submission_tasklet(struct tasklet_struct *t)
> > @@ -463,27 +501,165 @@ static void cs_irq_handler(struct intel_engine_cs *engine, u16 iir)
> >   		intel_engine_signal_breadcrumbs(engine);
> >   }
> > -static void guc_reset_prepare(struct intel_engine_cs *engine)
> > +static void __guc_context_destroy(struct intel_context *ce);
> > +static void release_guc_id(struct intel_guc *guc, struct intel_context *ce);
> > +static void guc_signal_context_fence(struct intel_context *ce);
> > +
> > +static void scrub_guc_desc_for_outstanding_g2h(struct intel_guc *guc)
> > +{
> > +	struct intel_context *ce;
> > +	unsigned long index, flags;
> > +	bool pending_disable, pending_enable, deregister, destroyed;
> > +
> > +	xa_for_each(&guc->context_lookup, index, ce) {
> > +		/* Flush context */
> > +		spin_lock_irqsave(&ce->guc_state.lock, flags);
> > +		spin_unlock_irqrestore(&ce->guc_state.lock, flags);
> > +
> > +		/*
> > +		 * Once we are at this point submission_disabled() is guaranteed
> > +		 * to visible to all callers who set the below flags (see above
> > +		 * flush and flushes in reset_prepare). If submission_disabled()
> > +		 * is set, the caller shouldn't set these flags.
> > +		 */
> > +
> > +		destroyed = context_destroyed(ce);
> > +		pending_enable = context_pending_enable(ce);
> > +		pending_disable = context_pending_disable(ce);
> > +		deregister = context_wait_for_deregister_to_register(ce);
> > +		init_sched_state(ce);
> > +
> > +		if (pending_enable || destroyed || deregister) {
> > +			atomic_dec(&guc->outstanding_submission_g2h);
> > +			if (deregister)
> > +				guc_signal_context_fence(ce);
> > +			if (destroyed) {
> > +				release_guc_id(guc, ce);
> > +				__guc_context_destroy(ce);
> > +			}
> > +			if (pending_enable|| deregister)
> > +				intel_context_put(ce);
> > +		}
> > +
> > +		/* Not mutualy exclusive with above if statement. */
> > +		if (pending_disable) {
> > +			guc_signal_context_fence(ce);
> > +			intel_context_sched_disable_unpin(ce);
> > +			atomic_dec(&guc->outstanding_submission_g2h);
> > +			intel_context_put(ce);
> > +		}
> > +	}
> > +}
> > +
> > +static inline bool
> > +submission_disabled(struct intel_guc *guc)
> > +{
> > +	struct i915_sched_engine * const sched_engine = guc->sched_engine;
> > +
> > +	return unlikely(!__tasklet_is_enabled(&sched_engine->tasklet));
> > +}
> > +
> > +static void disable_submission(struct intel_guc *guc)
> > +{
> > +	struct i915_sched_engine * const sched_engine = guc->sched_engine;
> > +
> > +	if (__tasklet_is_enabled(&sched_engine->tasklet)) {
> > +		GEM_BUG_ON(!guc->ct.enabled);
> > +		__tasklet_disable_sync_once(&sched_engine->tasklet);
> > +		sched_engine->tasklet.callback = NULL;
> > +	}
> > +}
> > +
> > +static void enable_submission(struct intel_guc *guc)
> > +{
> > +	struct i915_sched_engine * const sched_engine = guc->sched_engine;
> > +	unsigned long flags;
> > +
> > +	spin_lock_irqsave(&guc->sched_engine->lock, flags);
> > +	sched_engine->tasklet.callback = guc_submission_tasklet;
> > +	wmb();
> > +	if (!__tasklet_is_enabled(&sched_engine->tasklet) &&
> > +	    __tasklet_enable(&sched_engine->tasklet)) {
> > +		GEM_BUG_ON(!guc->ct.enabled);
> > +
> > +		/* And kick in case we missed a new request submission. */
> > +		tasklet_hi_schedule(&sched_engine->tasklet);
> > +	}
> > +	spin_unlock_irqrestore(&guc->sched_engine->lock, flags);
> > +}
> > +
> > +static void guc_flush_submissions(struct intel_guc *guc)
> >   {
> > -	ENGINE_TRACE(engine, "\n");
> > +	struct i915_sched_engine * const sched_engine = guc->sched_engine;
> > +	unsigned long flags;
> > +
> > +	spin_lock_irqsave(&sched_engine->lock, flags);
> > +	spin_unlock_irqrestore(&sched_engine->lock, flags);
> > +}
> > +
> > +void intel_guc_submission_reset_prepare(struct intel_guc *guc)
> > +{
> > +	int i;
> > +
> > +	if (unlikely(!guc_submission_initialized(guc)))
> > +		/* Reset called during driver load? GuC not yet initialised! */
> > +		return;
> > +
> > +	disable_submission(guc);
> > +	guc->interrupts.disable(guc);
> > +
> > +	/* Flush IRQ handler */
> > +	spin_lock_irq(&guc_to_gt(guc)->irq_lock);
> > +	spin_unlock_irq(&guc_to_gt(guc)->irq_lock);
> > +
> > +	guc_flush_submissions(guc);
> >   	/*
> > -	 * Prevent request submission to the hardware until we have
> > -	 * completed the reset in i915_gem_reset_finish(). If a request
> > -	 * is completed by one engine, it may then queue a request
> > -	 * to a second via its execlists->tasklet *just* as we are
> > -	 * calling engine->init_hw() and also writing the ELSP.
> > -	 * Turning off the execlists->tasklet until the reset is over
> > -	 * prevents the race.
> > -	 */
> > -	__tasklet_disable_sync_once(&engine->sched_engine->tasklet);
> > +	 * Handle any outstanding G2Hs before reset. Call IRQ handler directly
> > +	 * each pass as interrupt have been disabled. We always scrub for
> > +	 * outstanding G2H as it is possible for outstanding_submission_g2h to
> > +	 * be incremented after the context state update.
> > + 	 */
> > +	for (i = 0; i < 4 && atomic_read(&guc->outstanding_submission_g2h); ++i) {
> > +		intel_guc_to_host_event_handler(guc);
> > +#define wait_for_reset(guc, wait_var) \
> > +		guc_wait_for_pending_msg(guc, wait_var, false, (HZ / 20))
> > +		do {
> > +			wait_for_reset(guc, &guc->outstanding_submission_g2h);
> > +		} while (!list_empty(&guc->ct.requests.incoming));
> > +	}
> > +	scrub_guc_desc_for_outstanding_g2h(guc);
> >   }
> > -static void guc_reset_state(struct intel_context *ce,
> > -			    struct intel_engine_cs *engine,
> > -			    u32 head,
> > -			    bool scrub)
> > +static struct intel_engine_cs *
> > +guc_virtual_get_sibling(struct intel_engine_cs *ve, unsigned int sibling)
> >   {
> > +	struct intel_engine_cs *engine;
> > +	intel_engine_mask_t tmp, mask = ve->mask;
> > +	unsigned int num_siblings = 0;
> > +
> > +	for_each_engine_masked(engine, ve->gt, mask, tmp)
> > +		if (num_siblings++ == sibling)
> > +			return engine;
> > +
> > +	return NULL;
> > +}
> > +
> > +static inline struct intel_engine_cs *
> > +__context_to_physical_engine(struct intel_context *ce)
> > +{
> > +	struct intel_engine_cs *engine = ce->engine;
> > +
> > +	if (intel_engine_is_virtual(engine))
> > +		engine = guc_virtual_get_sibling(engine, 0);
> > +
> > +	return engine;
> > +}
> > +
> > +static void guc_reset_state(struct intel_context *ce, u32 head, bool scrub)
> > +{
> > +	struct intel_engine_cs *engine = __context_to_physical_engine(ce);
> > +
> >   	GEM_BUG_ON(!intel_context_is_pinned(ce));
> >   	/*
> > @@ -501,42 +677,147 @@ static void guc_reset_state(struct intel_context *ce,
> >   	lrc_update_regs(ce, engine, head);
> >   }
> > -static void guc_reset_rewind(struct intel_engine_cs *engine, bool stalled)
> > +static void guc_reset_nop(struct intel_engine_cs *engine)
> >   {
> > -	struct intel_engine_execlists * const execlists = &engine->execlists;
> > -	struct i915_request *rq;
> > +}
> > +
> > +static void guc_rewind_nop(struct intel_engine_cs *engine, bool stalled)
> > +{
> > +}
> > +
> > +static void
> > +__unwind_incomplete_requests(struct intel_context *ce)
> > +{
> > +	struct i915_request *rq, *rn;
> > +	struct list_head *pl;
> > +	int prio = I915_PRIORITY_INVALID;
> > +	struct i915_sched_engine * const sched_engine =
> > +		ce->engine->sched_engine;
> >   	unsigned long flags;
> > -	spin_lock_irqsave(&engine->sched_engine->lock, flags);
> > +	spin_lock_irqsave(&sched_engine->lock, flags);
> > +	spin_lock(&ce->guc_active.lock);
> > +	list_for_each_entry_safe(rq, rn,
> > +				 &ce->guc_active.requests,
> > +				 sched.link) {
> > +		if (i915_request_completed(rq))
> > +			continue;
> > +
> > +		list_del_init(&rq->sched.link);
> > +		spin_unlock(&ce->guc_active.lock);
> > +
> > +		__i915_request_unsubmit(rq);
> > +
> > +		/* Push the request back into the queue for later resubmission. */
> > +		GEM_BUG_ON(rq_prio(rq) == I915_PRIORITY_INVALID);
> > +		if (rq_prio(rq) != prio) {
> > +			prio = rq_prio(rq);
> > +			pl = i915_sched_lookup_priolist(sched_engine, prio);
> > +		}
> > +		GEM_BUG_ON(i915_sched_engine_is_empty(sched_engine));
> > +
> > +		list_add_tail(&rq->sched.link, pl);
> > +		set_bit(I915_FENCE_FLAG_PQUEUE, &rq->fence.flags);
> > -	/* Push back any incomplete requests for replay after the reset. */
> > -	rq = execlists_unwind_incomplete_requests(execlists);
> > -	if (!rq)
> > -		goto out_unlock;
> > +		spin_lock(&ce->guc_active.lock);
> > +	}
> > +	spin_unlock(&ce->guc_active.lock);
> > +	spin_unlock_irqrestore(&sched_engine->lock, flags);
> > +}
> > +
> > +static struct i915_request *context_find_active_request(struct intel_context *ce)
> > +{
> > +	struct i915_request *rq, *active = NULL;
> > +	unsigned long flags;
> > +
> > +	spin_lock_irqsave(&ce->guc_active.lock, flags);
> > +	list_for_each_entry_reverse(rq, &ce->guc_active.requests,
> > +				    sched.link) {
> > +		if (i915_request_completed(rq))
> > +			break;
> > +
> > +		active = rq;
> > +	}
> > +	spin_unlock_irqrestore(&ce->guc_active.lock, flags);
> > +
> > +	return active;
> > +}
> > +
> > +static void __guc_reset_context(struct intel_context *ce, bool stalled)
> > +{
> > +	struct i915_request *rq;
> > +	u32 head;
> > +
> > +	/*
> > +	 * GuC will implicitly mark the context as non-schedulable
> > +	 * when it sends the reset notification. Make sure our state
> > +	 * reflects this change. The context will be marked enabled
> > +	 * on resubmission.
> > +	 */
> > +	clr_context_enabled(ce);
> > +
> > +	rq = context_find_active_request(ce);
> > +	if (!rq) {
> > +		head = ce->ring->tail;
> > +		stalled = false;
> > +		goto out_replay;
> > +	}
> >   	if (!i915_request_started(rq))
> >   		stalled = false;
> > +	GEM_BUG_ON(i915_active_is_idle(&ce->active));
> > +	head = intel_ring_wrap(ce->ring, rq->head);
> >   	__i915_request_reset(rq, stalled);
> > -	guc_reset_state(rq->context, engine, rq->head, stalled);
> > -out_unlock:
> > -	spin_unlock_irqrestore(&engine->sched_engine->lock, flags);
> > +out_replay:
> > +	guc_reset_state(ce, head, stalled);
> > +	__unwind_incomplete_requests(ce);
> >   }
> > -static void guc_reset_cancel(struct intel_engine_cs *engine)
> > +void intel_guc_submission_reset(struct intel_guc *guc, bool stalled)
> > +{
> > +	struct intel_context *ce;
> > +	unsigned long index;
> > +
> > +	if (unlikely(!guc_submission_initialized(guc)))
> > +		/* Reset called during driver load? GuC not yet initialised! */
> > +		return;
> > +
> > +	xa_for_each(&guc->context_lookup, index, ce)
> > +		if (intel_context_is_pinned(ce))
> > +			__guc_reset_context(ce, stalled);
> > +
> > +	/* GuC is blown away, drop all references to contexts */
> > +	xa_destroy(&guc->context_lookup);
> > +}
> > +
> > +static void guc_cancel_context_requests(struct intel_context *ce)
> > +{
> > +	struct i915_sched_engine *sched_engine = ce_to_guc(ce)->sched_engine;
> > +	struct i915_request *rq;
> > +	unsigned long flags;
> > +
> > +	/* Mark all executing requests as skipped. */
> > +	spin_lock_irqsave(&sched_engine->lock, flags);
> > +	spin_lock(&ce->guc_active.lock);
> > +	list_for_each_entry(rq, &ce->guc_active.requests, sched.link)
> > +		i915_request_put(i915_request_mark_eio(rq));
> > +	spin_unlock(&ce->guc_active.lock);
> > +	spin_unlock_irqrestore(&sched_engine->lock, flags);
> > +}
> > +
> > +static void
> > +guc_cancel_sched_engine_requests(struct i915_sched_engine *sched_engine)
> >   {
> > -	struct i915_sched_engine * const sched_engine = engine->sched_engine;
> >   	struct i915_request *rq, *rn;
> >   	struct rb_node *rb;
> >   	unsigned long flags;
> >   	/* Can be called during boot if GuC fails to load */
> > -	if (!engine->gt)
> > +	if (!sched_engine)
> >   		return;
> > -	ENGINE_TRACE(engine, "\n");
> > -
> >   	/*
> >   	 * Before we call engine->cancel_requests(), we should have exclusive
> >   	 * access to the submission state. This is arranged for us by the
> > @@ -553,21 +834,16 @@ static void guc_reset_cancel(struct intel_engine_cs *engine)
> >   	 */
> >   	spin_lock_irqsave(&sched_engine->lock, flags);
> > -	/* Mark all executing requests as skipped. */
> > -	list_for_each_entry(rq, &sched_engine->requests, sched.link) {
> > -		i915_request_set_error_once(rq, -EIO);
> > -		i915_request_mark_complete(rq);
> > -	}
> > -
> >   	/* Flush the queued requests to the timeline list (for retiring). */
> >   	while ((rb = rb_first_cached(&sched_engine->queue))) {
> >   		struct i915_priolist *p = to_priolist(rb);
> >   		priolist_for_each_request_consume(rq, rn, p) {
> >   			list_del_init(&rq->sched.link);
> > +
> >   			__i915_request_submit(rq);
> > -			dma_fence_set_error(&rq->fence, -EIO);
> > -			i915_request_mark_complete(rq);
> > +
> > +			i915_request_put(i915_request_mark_eio(rq));
> >   		}
> >   		rb_erase_cached(&p->node, &sched_engine->queue);
> > @@ -582,14 +858,38 @@ static void guc_reset_cancel(struct intel_engine_cs *engine)
> >   	spin_unlock_irqrestore(&sched_engine->lock, flags);
> >   }
> > -static void guc_reset_finish(struct intel_engine_cs *engine)
> > +void intel_guc_submission_cancel_requests(struct intel_guc *guc)
> >   {
> > -	if (__tasklet_enable(&engine->sched_engine->tasklet))
> > -		/* And kick in case we missed a new request submission. */
> > -		tasklet_hi_schedule(&engine->sched_engine->tasklet);
> > +	struct intel_context *ce;
> > +	unsigned long index;
> > +
> > +	xa_for_each(&guc->context_lookup, index, ce)
> > +		if (intel_context_is_pinned(ce))
> > +			guc_cancel_context_requests(ce);
> > -	ENGINE_TRACE(engine, "depth->%d\n",
> > -		     atomic_read(&engine->sched_engine->tasklet.count));
> > +	guc_cancel_sched_engine_requests(guc->sched_engine);
> > +
> > +	/* GuC is blown away, drop all references to contexts */
> > +	xa_destroy(&guc->context_lookup);
> > +}
> > +
> > +void intel_guc_submission_reset_finish(struct intel_guc *guc)
> > +{
> > +	/* Reset called during driver load or during wedge? */
> > +	if (unlikely(!guc_submission_initialized(guc) ||
> > +		     test_bit(I915_WEDGED, &guc_to_gt(guc)->reset.flags)))
> > +		return;
> > +
> > +	/*
> > +	 * Technically possible for either of these values to be non-zero here,
> > +	 * but very unlikely + harmless. Regardless let's add a warn so we can
> > +	 * see in CI if this happens frequently / a precursor to taking down the
> > +	 * machine.
> > +	 */
> > +	GEM_WARN_ON(atomic_read(&guc->outstanding_submission_g2h));
> > +	atomic_set(&guc->outstanding_submission_g2h, 0);
> > +
> > +	enable_submission(guc);
> >   }
> >   /*
> > @@ -656,6 +956,9 @@ static int guc_bypass_tasklet_submit(struct intel_guc *guc,
> >   	else
> >   		trace_i915_request_guc_submit(rq);
> > +	if (unlikely(ret == -EIO))
> > +		disable_submission(guc);
> > +
> >   	return ret;
> >   }
> > @@ -668,7 +971,8 @@ static void guc_submit_request(struct i915_request *rq)
> >   	/* Will be called from irq-context when using foreign fences. */
> >   	spin_lock_irqsave(&sched_engine->lock, flags);
> > -	if (guc->stalled_request || !i915_sched_engine_is_empty(sched_engine))
> > +	if (submission_disabled(guc) || guc->stalled_request ||
> > +	    !i915_sched_engine_is_empty(sched_engine))
> >   		queue_request(sched_engine, rq, rq_prio(rq));
> >   	else if (guc_bypass_tasklet_submit(guc, rq) == -EBUSY)
> >   		tasklet_hi_schedule(&sched_engine->tasklet);
> > @@ -805,7 +1109,8 @@ static void unpin_guc_id(struct intel_guc *guc, struct intel_context *ce)
> >   static int __guc_action_register_context(struct intel_guc *guc,
> >   					 u32 guc_id,
> > -					 u32 offset)
> > +					 u32 offset,
> > +					 bool loop)
> >   {
> >   	u32 action[] = {
> >   		INTEL_GUC_ACTION_REGISTER_CONTEXT,
> > @@ -813,10 +1118,10 @@ static int __guc_action_register_context(struct intel_guc *guc,
> >   		offset,
> >   	};
> > -	return guc_submission_busy_loop(guc, action, ARRAY_SIZE(action), 0, true);
> > +	return guc_submission_busy_loop(guc, action, ARRAY_SIZE(action), 0, loop);
> >   }
> > -static int register_context(struct intel_context *ce)
> > +static int register_context(struct intel_context *ce, bool loop)
> >   {
> >   	struct intel_guc *guc = ce_to_guc(ce);
> >   	u32 offset = intel_guc_ggtt_offset(guc, guc->lrc_desc_pool) +
> > @@ -824,11 +1129,12 @@ static int register_context(struct intel_context *ce)
> >   	trace_intel_context_register(ce);
> > -	return __guc_action_register_context(guc, ce->guc_id, offset);
> > +	return __guc_action_register_context(guc, ce->guc_id, offset, loop);
> >   }
> >   static int __guc_action_deregister_context(struct intel_guc *guc,
> > -					   u32 guc_id)
> > +					   u32 guc_id,
> > +					   bool loop)
> >   {
> >   	u32 action[] = {
> >   		INTEL_GUC_ACTION_DEREGISTER_CONTEXT,
> > @@ -836,16 +1142,16 @@ static int __guc_action_deregister_context(struct intel_guc *guc,
> >   	};
> >   	return guc_submission_busy_loop(guc, action, ARRAY_SIZE(action),
> > -					G2H_LEN_DW_DEREGISTER_CONTEXT, true);
> > +					G2H_LEN_DW_DEREGISTER_CONTEXT, loop);
> >   }
> > -static int deregister_context(struct intel_context *ce, u32 guc_id)
> > +static int deregister_context(struct intel_context *ce, u32 guc_id, bool loop)
> >   {
> >   	struct intel_guc *guc = ce_to_guc(ce);
> >   	trace_intel_context_deregister(ce);
> > -	return __guc_action_deregister_context(guc, guc_id);
> > +	return __guc_action_deregister_context(guc, guc_id, loop);
> >   }
> >   static intel_engine_mask_t adjust_engine_mask(u8 class, intel_engine_mask_t mask)
> > @@ -874,7 +1180,7 @@ static void guc_context_policy_init(struct intel_engine_cs *engine,
> >   	desc->preemption_timeout = CONTEXT_POLICY_DEFAULT_PREEMPTION_TIME_US;
> >   }
> > -static int guc_lrc_desc_pin(struct intel_context *ce)
> > +static int guc_lrc_desc_pin(struct intel_context *ce, bool loop)
> >   {
> >   	struct intel_runtime_pm *runtime_pm =
> >   		&ce->engine->gt->i915->runtime_pm;
> > @@ -920,18 +1226,44 @@ static int guc_lrc_desc_pin(struct intel_context *ce)
> >   	 */
> >   	if (context_registered) {
> >   		trace_intel_context_steal_guc_id(ce);
> > -		set_context_wait_for_deregister_to_register(ce);
> > -		intel_context_get(ce);
> > +		if (!loop) {
> > +			set_context_wait_for_deregister_to_register(ce);
> > +			intel_context_get(ce);
> > +		} else {
> > +			bool disabled;
> > +			unsigned long flags;
> > +
> > +			/* Seal race with Reset */
> > +			spin_lock_irqsave(&ce->guc_state.lock, flags);
> > +			disabled = submission_disabled(guc);
> > +			if (likely(!disabled)) {
> > +				set_context_wait_for_deregister_to_register(ce);
> > +				intel_context_get(ce);
> > +			}
> > +			spin_unlock_irqrestore(&ce->guc_state.lock, flags);
> > +			if (unlikely(disabled)) {
> > +				reset_lrc_desc(guc, desc_idx);
> > +				return 0;	/* Will get registered later */
> > +			}
> > +		}
> >   		/*
> >   		 * If stealing the guc_id, this ce has the same guc_id as the
> >   		 * context whos guc_id was stole.
> >   		 */
> >   		with_intel_runtime_pm(runtime_pm, wakeref)
> > -			ret = deregister_context(ce, ce->guc_id);
> > +			ret = deregister_context(ce, ce->guc_id, loop);
> > +		if (unlikely(ret == -EBUSY)) {
> > +			clr_context_wait_for_deregister_to_register(ce);
> > +			intel_context_put(ce);
> > +		}
> >   	} else {
> >   		with_intel_runtime_pm(runtime_pm, wakeref)
> > -			ret = register_context(ce);
> > +			ret = register_context(ce, loop);
> > +		if (unlikely(ret == -EBUSY))
> > +			reset_lrc_desc(guc, desc_idx);
> > +		else if (unlikely(ret == -ENODEV))
> > +			ret = 0;	/* Will get registered later */
> >   	}
> >   	return ret;
> > @@ -994,7 +1326,6 @@ static void __guc_context_sched_disable(struct intel_guc *guc,
> >   	GEM_BUG_ON(guc_id == GUC_INVALID_LRC_ID);
> >   	trace_intel_context_sched_disable(ce);
> > -	intel_context_get(ce);
> >   	guc_submission_busy_loop(guc, action, ARRAY_SIZE(action),
> >   				 G2H_LEN_DW_SCHED_CONTEXT_MODE_SET, true);
> > @@ -1004,6 +1335,7 @@ static u16 prep_context_pending_disable(struct intel_context *ce)
> >   {
> >   	set_context_pending_disable(ce);
> >   	clr_context_enabled(ce);
> > +	intel_context_get(ce);
> >   	return ce->guc_id;
> >   }
> > @@ -1016,7 +1348,7 @@ static void guc_context_sched_disable(struct intel_context *ce)
> >   	u16 guc_id;
> >   	intel_wakeref_t wakeref;
> > -	if (context_guc_id_invalid(ce) ||
> > +	if (submission_disabled(guc) || context_guc_id_invalid(ce) ||
> >   	    !lrc_desc_registered(guc, ce->guc_id)) {
> >   		clr_context_enabled(ce);
> >   		goto unpin;
> > @@ -1034,6 +1366,7 @@ static void guc_context_sched_disable(struct intel_context *ce)
> >   	 * request doesn't slip through the 'context_pending_disable' fence.
> >   	 */
> >   	if (unlikely(atomic_add_unless(&ce->pin_count, -2, 2))) {
> > +		spin_unlock_irqrestore(&ce->guc_state.lock, flags);
> >   		return;
> >   	}
> >   	guc_id = prep_context_pending_disable(ce);
> > @@ -1050,19 +1383,13 @@ static void guc_context_sched_disable(struct intel_context *ce)
> >   static inline void guc_lrc_desc_unpin(struct intel_context *ce)
> >   {
> > -	struct intel_engine_cs *engine = ce->engine;
> > -	struct intel_guc *guc = &engine->gt->uc.guc;
> > -	unsigned long flags;
> > +	struct intel_guc *guc = ce_to_guc(ce);
> >   	GEM_BUG_ON(!lrc_desc_registered(guc, ce->guc_id));
> >   	GEM_BUG_ON(ce != __get_context(guc, ce->guc_id));
> >   	GEM_BUG_ON(context_enabled(ce));
> > -	spin_lock_irqsave(&ce->guc_state.lock, flags);
> > -	set_context_destroyed(ce);
> > -	spin_unlock_irqrestore(&ce->guc_state.lock, flags);
> > -
> > -	deregister_context(ce, ce->guc_id);
> > +	deregister_context(ce, ce->guc_id, true);
> >   }
> >   static void __guc_context_destroy(struct intel_context *ce)
> > @@ -1090,13 +1417,15 @@ static void guc_context_destroy(struct kref *kref)
> >   	struct intel_guc *guc = &ce->engine->gt->uc.guc;
> >   	intel_wakeref_t wakeref;
> >   	unsigned long flags;
> > +	bool disabled;
> >   	/*
> >   	 * If the guc_id is invalid this context has been stolen and we can free
> >   	 * it immediately. Also can be freed immediately if the context is not
> >   	 * registered with the GuC.
> >   	 */
> > -	if (context_guc_id_invalid(ce) ||
> > +	if (submission_disabled(guc) ||
> > +	    context_guc_id_invalid(ce) ||
> >   	    !lrc_desc_registered(guc, ce->guc_id)) {
> >   		release_guc_id(guc, ce);
> >   		__guc_context_destroy(ce);
> > @@ -1123,6 +1452,18 @@ static void guc_context_destroy(struct kref *kref)
> >   		list_del_init(&ce->guc_id_link);
> >   	spin_unlock_irqrestore(&guc->contexts_lock, flags);
> > +	/* Seal race with Reset */
> > +	spin_lock_irqsave(&ce->guc_state.lock, flags);
> > +	disabled = submission_disabled(guc);
> > +	if (likely(!disabled))
> > +		set_context_destroyed(ce);
> > +	spin_unlock_irqrestore(&ce->guc_state.lock, flags);
> > +	if (unlikely(disabled)) {
> > +		release_guc_id(guc, ce);
> > +		__guc_context_destroy(ce);
> > +		return;
> > +	}
> > +
> >   	/*
> >   	 * We defer GuC context deregistration until the context is destroyed
> >   	 * in order to save on CTBs. With this optimization ideally we only need
> > @@ -1145,6 +1486,33 @@ static int guc_context_alloc(struct intel_context *ce)
> >   	return lrc_alloc(ce, ce->engine);
> >   }
> > +static void add_to_context(struct i915_request *rq)
> > +{
> > +	struct intel_context *ce = rq->context;
> > +
> > +	spin_lock(&ce->guc_active.lock);
> > +	list_move_tail(&rq->sched.link, &ce->guc_active.requests);
> > +	spin_unlock(&ce->guc_active.lock);
> > +}
> > +
> > +static void remove_from_context(struct i915_request *rq)
> > +{
> > +	struct intel_context *ce = rq->context;
> > +
> > +	spin_lock_irq(&ce->guc_active.lock);
> > +
> > +	list_del_init(&rq->sched.link);
> > +	clear_bit(I915_FENCE_FLAG_PQUEUE, &rq->fence.flags);
> > +
> > +	/* Prevent further __await_execution() registering a cb, then flush */
> > +	set_bit(I915_FENCE_FLAG_ACTIVE, &rq->fence.flags);
> > +
> > +	spin_unlock_irq(&ce->guc_active.lock);
> > +
> > +	atomic_dec(&ce->guc_id_ref);
> > +	i915_request_notify_execute_cb_imm(rq);
> > +}
> > +
> >   static const struct intel_context_ops guc_context_ops = {
> >   	.alloc = guc_context_alloc,
> > @@ -1183,8 +1551,6 @@ static void guc_signal_context_fence(struct intel_context *ce)
> >   {
> >   	unsigned long flags;
> > -	GEM_BUG_ON(!context_wait_for_deregister_to_register(ce));
> > -
> >   	spin_lock_irqsave(&ce->guc_state.lock, flags);
> >   	clr_context_wait_for_deregister_to_register(ce);
> >   	__guc_signal_context_fence(ce);
> > @@ -1193,8 +1559,9 @@ static void guc_signal_context_fence(struct intel_context *ce)
> >   static bool context_needs_register(struct intel_context *ce, bool new_guc_id)
> >   {
> > -	return new_guc_id || test_bit(CONTEXT_LRCA_DIRTY, &ce->flags) ||
> > -		!lrc_desc_registered(ce_to_guc(ce), ce->guc_id);
> > +	return (new_guc_id || test_bit(CONTEXT_LRCA_DIRTY, &ce->flags) ||
> > +		!lrc_desc_registered(ce_to_guc(ce), ce->guc_id)) &&
> > +		!submission_disabled(ce_to_guc(ce));
> >   }
> >   static int guc_request_alloc(struct i915_request *rq)
> > @@ -1252,8 +1619,12 @@ static int guc_request_alloc(struct i915_request *rq)
> >   	if (unlikely(ret < 0))
> >   		return ret;;
> >   	if (context_needs_register(ce, !!ret)) {
> > -		ret = guc_lrc_desc_pin(ce);
> > +		ret = guc_lrc_desc_pin(ce, true);
> >   		if (unlikely(ret)) {	/* unwind */
> > +			if (ret == -EIO) {
> > +				disable_submission(guc);
> > +				goto out;	/* GPU will be reset */
> > +			}
> >   			atomic_dec(&ce->guc_id_ref);
> >   			unpin_guc_id(guc, ce);
> >   			return ret;
> > @@ -1290,20 +1661,6 @@ static int guc_request_alloc(struct i915_request *rq)
> >   	return 0;
> >   }
> > -static struct intel_engine_cs *
> > -guc_virtual_get_sibling(struct intel_engine_cs *ve, unsigned int sibling)
> > -{
> > -	struct intel_engine_cs *engine;
> > -	intel_engine_mask_t tmp, mask = ve->mask;
> > -	unsigned int num_siblings = 0;
> > -
> > -	for_each_engine_masked(engine, ve->gt, mask, tmp)
> > -		if (num_siblings++ == sibling)
> > -			return engine;
> > -
> > -	return NULL;
> > -}
> > -
> >   static int guc_virtual_context_pre_pin(struct intel_context *ce,
> >   				       struct i915_gem_ww_ctx *ww,
> >   				       void **vaddr)
> > @@ -1512,7 +1869,7 @@ static inline void guc_kernel_context_pin(struct intel_guc *guc,
> >   {
> >   	if (context_guc_id_invalid(ce))
> >   		pin_guc_id(guc, ce);
> > -	guc_lrc_desc_pin(ce);
> > +	guc_lrc_desc_pin(ce, true);
> >   }
> >   static inline void guc_init_lrc_mapping(struct intel_guc *guc)
> > @@ -1578,13 +1935,15 @@ static void guc_default_vfuncs(struct intel_engine_cs *engine)
> >   	engine->cops = &guc_context_ops;
> >   	engine->request_alloc = guc_request_alloc;
> >   	engine->bump_serial = guc_bump_serial;
> > +	engine->add_active_request = add_to_context;
> > +	engine->remove_active_request = remove_from_context;
> >   	engine->sched_engine->schedule = i915_schedule;
> > -	engine->reset.prepare = guc_reset_prepare;
> > -	engine->reset.rewind = guc_reset_rewind;
> > -	engine->reset.cancel = guc_reset_cancel;
> > -	engine->reset.finish = guc_reset_finish;
> > +	engine->reset.prepare = guc_reset_nop;
> > +	engine->reset.rewind = guc_rewind_nop;
> > +	engine->reset.cancel = guc_reset_nop;
> > +	engine->reset.finish = guc_reset_nop;
> >   	engine->emit_flush = gen8_emit_flush_xcs;
> >   	engine->emit_init_breadcrumb = gen8_emit_init_breadcrumb;
> > @@ -1757,7 +2116,7 @@ int intel_guc_deregister_done_process_msg(struct intel_guc *guc,
> >   		 * register this context.
> >   		 */
> >   		with_intel_runtime_pm(runtime_pm, wakeref)
> > -			register_context(ce);
> > +			register_context(ce, true);
> >   		guc_signal_context_fence(ce);
> >   		intel_context_put(ce);
> >   	} else if (context_destroyed(ce)) {
> > @@ -1939,6 +2298,10 @@ guc_create_virtual(struct intel_engine_cs **siblings, unsigned int count)
> >   				 "v%dx%d", ve->base.class, count);
> >   			ve->base.context_size = sibling->context_size;
> > +			ve->base.add_active_request =
> > +				sibling->add_active_request;
> > +			ve->base.remove_active_request =
> > +				sibling->remove_active_request;
> >   			ve->base.emit_bb_start = sibling->emit_bb_start;
> >   			ve->base.emit_flush = sibling->emit_flush;
> >   			ve->base.emit_init_breadcrumb =
> > diff --git a/drivers/gpu/drm/i915/gt/uc/intel_uc.c b/drivers/gpu/drm/i915/gt/uc/intel_uc.c
> > index 6d8b9233214e..f0b02200aa01 100644
> > --- a/drivers/gpu/drm/i915/gt/uc/intel_uc.c
> > +++ b/drivers/gpu/drm/i915/gt/uc/intel_uc.c
> > @@ -565,12 +565,49 @@ void intel_uc_reset_prepare(struct intel_uc *uc)
> >   {
> >   	struct intel_guc *guc = &uc->guc;
> > -	if (!intel_guc_is_ready(guc))
> > +
> > +	/* Nothing to do if GuC isn't supported */
> > +	if (!intel_uc_supports_guc(uc))
> >   		return;
> > +	/* Firmware expected to be running when this function is called */
> > +	if (!intel_guc_is_ready(guc))
> > +		goto sanitize;
> > +
> > +	if (intel_uc_uses_guc_submission(uc))
> > +		intel_guc_submission_reset_prepare(guc);
> > +
> > +sanitize:
> >   	__uc_sanitize(uc);
> >   }
> > +void intel_uc_reset(struct intel_uc *uc, bool stalled)
> > +{
> > +	struct intel_guc *guc = &uc->guc;
> > +
> > +	/* Firmware can not be running when this function is called  */
> > +	if (intel_uc_uses_guc_submission(uc))
> > +		intel_guc_submission_reset(guc, stalled);
> > +}
> > +
> > +void intel_uc_reset_finish(struct intel_uc *uc)
> > +{
> > +	struct intel_guc *guc = &uc->guc;
> > +
> > +	/* Firmware expected to be running when this function is called */
> > +	if (intel_guc_is_fw_running(guc) && intel_uc_uses_guc_submission(uc))
> > +		intel_guc_submission_reset_finish(guc);
> > +}
> > +
> > +void intel_uc_cancel_requests(struct intel_uc *uc)
> > +{
> > +	struct intel_guc *guc = &uc->guc;
> > +
> > +	/* Firmware can not be running when this function is called  */
> > +	if (intel_uc_uses_guc_submission(uc))
> > +		intel_guc_submission_cancel_requests(guc);
> > +}
> > +
> >   void intel_uc_runtime_suspend(struct intel_uc *uc)
> >   {
> >   	struct intel_guc *guc = &uc->guc;
> > diff --git a/drivers/gpu/drm/i915/gt/uc/intel_uc.h b/drivers/gpu/drm/i915/gt/uc/intel_uc.h
> > index c4cef885e984..eaa3202192ac 100644
> > --- a/drivers/gpu/drm/i915/gt/uc/intel_uc.h
> > +++ b/drivers/gpu/drm/i915/gt/uc/intel_uc.h
> > @@ -37,6 +37,9 @@ void intel_uc_driver_late_release(struct intel_uc *uc);
> >   void intel_uc_driver_remove(struct intel_uc *uc);
> >   void intel_uc_init_mmio(struct intel_uc *uc);
> >   void intel_uc_reset_prepare(struct intel_uc *uc);
> > +void intel_uc_reset(struct intel_uc *uc, bool stalled);
> > +void intel_uc_reset_finish(struct intel_uc *uc);
> > +void intel_uc_cancel_requests(struct intel_uc *uc);
> >   void intel_uc_suspend(struct intel_uc *uc);
> >   void intel_uc_runtime_suspend(struct intel_uc *uc);
> >   int intel_uc_resume(struct intel_uc *uc);
> > diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
> > index dec5a35c9aa2..192784875a1d 100644
> > --- a/drivers/gpu/drm/i915/i915_request.c
> > +++ b/drivers/gpu/drm/i915/i915_request.c
> > @@ -194,7 +194,7 @@ static bool irq_work_imm(struct irq_work *wrk)
> >   	return false;
> >   }
> > -static void __notify_execute_cb_imm(struct i915_request *rq)
> > +void i915_request_notify_execute_cb_imm(struct i915_request *rq)
> >   {
> >   	__notify_execute_cb(rq, irq_work_imm);
> >   }
> > @@ -268,37 +268,6 @@ i915_request_active_engine(struct i915_request *rq,
> >   	return ret;
> >   }
> > -
> > -static void remove_from_engine(struct i915_request *rq)
> > -{
> > -	struct intel_engine_cs *engine, *locked;
> > -
> > -	/*
> > -	 * Virtual engines complicate acquiring the engine timeline lock,
> > -	 * as their rq->engine pointer is not stable until under that
> > -	 * engine lock. The simple ploy we use is to take the lock then
> > -	 * check that the rq still belongs to the newly locked engine.
> > -	 */
> > -	locked = READ_ONCE(rq->engine);
> > -	spin_lock_irq(&locked->sched_engine->lock);
> > -	while (unlikely(locked != (engine = READ_ONCE(rq->engine)))) {
> > -		spin_unlock(&locked->sched_engine->lock);
> > -		spin_lock(&engine->sched_engine->lock);
> > -		locked = engine;
> > -	}
> > -	list_del_init(&rq->sched.link);
> > -
> > -	clear_bit(I915_FENCE_FLAG_PQUEUE, &rq->fence.flags);
> > -	clear_bit(I915_FENCE_FLAG_HOLD, &rq->fence.flags);
> > -
> > -	/* Prevent further __await_execution() registering a cb, then flush */
> > -	set_bit(I915_FENCE_FLAG_ACTIVE, &rq->fence.flags);
> > -
> > -	spin_unlock_irq(&locked->sched_engine->lock);
> > -
> > -	__notify_execute_cb_imm(rq);
> > -}
> > -
> >   static void __rq_init_watchdog(struct i915_request *rq)
> >   {
> >   	rq->watchdog.timer.function = NULL;
> > @@ -395,9 +364,7 @@ bool i915_request_retire(struct i915_request *rq)
> >   	 * after removing the breadcrumb and signaling it, so that we do not
> >   	 * inadvertently attach the breadcrumb to a completed request.
> >   	 */
> > -	if (!list_empty(&rq->sched.link))
> > -		remove_from_engine(rq);
> > -	atomic_dec(&rq->context->guc_id_ref);
> > +	rq->engine->remove_active_request(rq);
> >   	GEM_BUG_ON(!llist_empty(&rq->execute_cb));
> >   	__list_del_entry(&rq->link); /* poison neither prev/next (RCU walks) */
> > @@ -539,7 +506,7 @@ __await_execution(struct i915_request *rq,
> >   	if (llist_add(&cb->work.node.llist, &signal->execute_cb)) {
> >   		if (i915_request_is_active(signal) ||
> >   		    __request_in_flight(signal))
> > -			__notify_execute_cb_imm(signal);
> > +			i915_request_notify_execute_cb_imm(signal);
> >   	}
> >   	return 0;
> > @@ -676,7 +643,7 @@ bool __i915_request_submit(struct i915_request *request)
> >   	result = true;
> >   	GEM_BUG_ON(test_bit(I915_FENCE_FLAG_ACTIVE, &request->fence.flags));
> > -	list_move_tail(&request->sched.link, &engine->sched_engine->requests);
> > +	engine->add_active_request(request);
> >   active:
> >   	clear_bit(I915_FENCE_FLAG_PQUEUE, &request->fence.flags);
> >   	set_bit(I915_FENCE_FLAG_ACTIVE, &request->fence.flags);
> > diff --git a/drivers/gpu/drm/i915/i915_request.h b/drivers/gpu/drm/i915/i915_request.h
> > index f870cd75a001..bcc6340c505e 100644
> > --- a/drivers/gpu/drm/i915/i915_request.h
> > +++ b/drivers/gpu/drm/i915/i915_request.h
> > @@ -649,4 +649,6 @@ bool
> >   i915_request_active_engine(struct i915_request *rq,
> >   			   struct intel_engine_cs **active);
> > +void i915_request_notify_execute_cb_imm(struct i915_request *rq);
> > +
> >   #endif /* I915_REQUEST_H */
> >

Tvrtko Ursulin July 27, 2021, 8:56 a.m. UTC | #5

On 26/07/2021 23:48, Matthew Brost wrote:
> On Thu, Jul 15, 2021 at 10:36:51AM +0100, Tvrtko Ursulin wrote:
>>
>> On 24/06/2021 08:05, Matthew Brost wrote:
>>> Reset implementation for new GuC interface. This is the legacy reset
>>> implementation which is called when the i915 owns the engine hang check.
>>> Future patches will offload the engine hang check to GuC but we will
>>> continue to maintain this legacy path as a fallback and this code path
>>> is also required if the GuC dies.
>>>
>>> With the new GuC interface it is not possible to reset individual
>>> engines - it is only possible to reset the GPU entirely. This patch
>>> forces an entire chip reset if any engine hangs.
>>
>> No updates after my review comments on 6th of May.
>>
>> At least:
>>
>> 1. wmb documentation
>>
> 
> Yea, missed this. Checkpatch yelled at me too. Will be fixed in next
> rev.
> 
>> 2. Spin lock cycling I either didn't understand or didn't buy the
>> explanation. I don't remember seeing that pattern elsewhere in the driver -
>> cycle a spinlock to make sure what was updated inside it is visible you
>> said?
>>
> 
> I did respond - not really my fault if you don't understand a fairly
> simple concept but I'll explain again.
> 
> Change a variable
> Cycle a lock
> At this point we know anyone that acquires above lock the variable
> change is visible.
> 
> I can't be the first person in the Linux kernel to do this nor in the
> i915.

Don't know, did not do an exhaustive search. I can understand it being 
used to make sure any lock taking sections would exit, if they happened 
to be running simultaneously to the lock cycling code, but you seem to 
be describing it being used as a memory barrier.

So either a code comment or just use a memory barrier is my ask. There 
is a requirement to comment memory barriers anyway so if this is 
effectively one of them it's pretty clear cut.

> This basically allows to seal all the reset races without a BKL.
> 
> Also I told you I explain in this a doc patch that will get reposted
> after GuC submission lands:
> https://patchwork.freedesktop.org/patch/432408/?series=89844&rev=1
> 
>> 3. Dropping the lock protecting the list in the middle of
>> list_for_each_entry_safe and just continuing to iterate like nothing
>> happened. (__unwind_incomplete_requests) Again, perhaps I did not understand
>> your explanation properly but you did appear to write:
>>
> 
> To be honest looking at the code now we likely don't need to drop the
> look but regardless I don't think we should change this for the
> following reasons.

Then don't?

> 1. I assure you this is safe and works. I can add a better comment
> explaining this though.

Yes please for a comment. Assurances are all good until a new bug is found.

> 2. This is thoroughly tested and resets are the hardest thing to get
> stable and working.

Well new bugs are found even after statements of things being well 
tested so I'd err on the side of caution. And I don't mean your code 
here but as a general principle.

> 3. This code is literally going to get deleted when we move to the DRM
> scheduler as all the tracking / unwinding / resubmission will be in the
> DRM scheduler core.

Yeah, but if that cannot be guaranteed to happen in the same kernel 
release then lets not put dodgy code in.

> 4. A 2 second search of the driver found that we do the same thing in
> intel_gt_retire_requests_timeout so this isn't unprecedented.

The code there is bit different. It uses list_safe_reset_next after 
re-acquiring the lock and only then unlinks the current element from the 
list.

It all boils down to whether something can modify the list in parallel 
in your case. If it can't, just don't take the lock but instead put a 
comment saying why the lock does not need to be taken would be my 
suggestion. That way you avoid having to explain why the iteration is 
not broken.

Regards,

Tvrtko

> 
> Matt
> 
>> """
>> We only need the active lock for ce->guc_active.requests list. It is
>> indeed safe to drop the lock.
>> """
>>
>> +	spin_lock(&ce->guc_active.lock);
>> +	list_for_each_entry_safe(rq, rn,
>> +				 &ce->guc_active.requests,
>> +				 sched.link) {
>> +		if (i915_request_completed(rq))
>> +			continue;
>> +
>> +		list_del_init(&rq->sched.link);
>> +		spin_unlock(&ce->guc_active.lock);
>> ...
>> +		spin_lock(&ce->guc_active.lock);
>> +	}
>>
>> Safe iterator guards against list_del but dropping the lock means the state
>> of the overall list can change so next pointer may or may not be valid,
>> requests may be missed, I don't know. Needs a comment explaining why it is
>> safe.
>>
>> Regards,
>>
>> Tvrtko
>>
>>>
>>> Cc: John Harrison <[e-mail]>
>>> Signed-off-by: Matthew Brost <[e-mail]>
>>> ---
>>>    drivers/gpu/drm/i915/gt/intel_context.c       |   3 +
>>>    drivers/gpu/drm/i915/gt/intel_context_types.h |   7 +
>>>    drivers/gpu/drm/i915/gt/intel_engine_types.h  |   6 +
>>>    .../drm/i915/gt/intel_execlists_submission.c  |  40 ++
>>>    drivers/gpu/drm/i915/gt/intel_gt_pm.c         |   6 +-
>>>    drivers/gpu/drm/i915/gt/intel_reset.c         |  18 +-
>>>    .../gpu/drm/i915/gt/intel_ring_submission.c   |  22 +
>>>    drivers/gpu/drm/i915/gt/mock_engine.c         |  31 +
>>>    drivers/gpu/drm/i915/gt/uc/intel_guc.c        |  13 -
>>>    drivers/gpu/drm/i915/gt/uc/intel_guc.h        |   8 +-
>>>    .../gpu/drm/i915/gt/uc/intel_guc_submission.c | 581 ++++++++++++++----
>>>    drivers/gpu/drm/i915/gt/uc/intel_uc.c         |  39 +-
>>>    drivers/gpu/drm/i915/gt/uc/intel_uc.h         |   3 +
>>>    drivers/gpu/drm/i915/i915_request.c           |  41 +-
>>>    drivers/gpu/drm/i915/i915_request.h           |   2 +
>>>    15 files changed, 649 insertions(+), 171 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/i915/gt/intel_context.c b/drivers/gpu/drm/i915/gt/intel_context.c
>>> index b24a1b7a3f88..2f01437056a8 100644
>>> --- a/drivers/gpu/drm/i915/gt/intel_context.c
>>> +++ b/drivers/gpu/drm/i915/gt/intel_context.c
>>> @@ -392,6 +392,9 @@ intel_context_init(struct intel_context *ce, struct intel_engine_cs *engine)
>>>    	spin_lock_init(&ce->guc_state.lock);
>>>    	INIT_LIST_HEAD(&ce->guc_state.fences);
>>> +	spin_lock_init(&ce->guc_active.lock);
>>> +	INIT_LIST_HEAD(&ce->guc_active.requests);
>>> +
>>>    	ce->guc_id = GUC_INVALID_LRC_ID;
>>>    	INIT_LIST_HEAD(&ce->guc_id_link);
>>> diff --git a/drivers/gpu/drm/i915/gt/intel_context_types.h b/drivers/gpu/drm/i915/gt/intel_context_types.h
>>> index 6945963a31ba..b63c8cf7823b 100644
>>> --- a/drivers/gpu/drm/i915/gt/intel_context_types.h
>>> +++ b/drivers/gpu/drm/i915/gt/intel_context_types.h
>>> @@ -165,6 +165,13 @@ struct intel_context {
>>>    		struct list_head fences;
>>>    	} guc_state;
>>> +	struct {
>>> +		/** lock: protects everything in guc_active */
>>> +		spinlock_t lock;
>>> +		/** requests: active requests on this context */
>>> +		struct list_head requests;
>>> +	} guc_active;
>>> +
>>>    	/* GuC scheduling state that does not require a lock. */
>>>    	atomic_t guc_sched_state_no_lock;
>>> diff --git a/drivers/gpu/drm/i915/gt/intel_engine_types.h b/drivers/gpu/drm/i915/gt/intel_engine_types.h
>>> index e7cb6a06db9d..f9d264c008e8 100644
>>> --- a/drivers/gpu/drm/i915/gt/intel_engine_types.h
>>> +++ b/drivers/gpu/drm/i915/gt/intel_engine_types.h
>>> @@ -426,6 +426,12 @@ struct intel_engine_cs {
>>>    	void		(*release)(struct intel_engine_cs *engine);
>>> +	/*
>>> +	 * Add / remove request from engine active tracking
>>> +	 */
>>> +	void		(*add_active_request)(struct i915_request *rq);
>>> +	void		(*remove_active_request)(struct i915_request *rq);
>>> +
>>>    	struct intel_engine_execlists execlists;
>>>    	/*
>>> diff --git a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
>>> index c10ea6080752..c301a2d088b1 100644
>>> --- a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
>>> +++ b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
>>> @@ -3118,6 +3118,42 @@ static void execlists_park(struct intel_engine_cs *engine)
>>>    	cancel_timer(&engine->execlists.preempt);
>>>    }
>>> +static void add_to_engine(struct i915_request *rq)
>>> +{
>>> +	lockdep_assert_held(&rq->engine->sched_engine->lock);
>>> +	list_move_tail(&rq->sched.link, &rq->engine->sched_engine->requests);
>>> +}
>>> +
>>> +static void remove_from_engine(struct i915_request *rq)
>>> +{
>>> +	struct intel_engine_cs *engine, *locked;
>>> +
>>> +	/*
>>> +	 * Virtual engines complicate acquiring the engine timeline lock,
>>> +	 * as their rq->engine pointer is not stable until under that
>>> +	 * engine lock. The simple ploy we use is to take the lock then
>>> +	 * check that the rq still belongs to the newly locked engine.
>>> +	 */
>>> +	locked = READ_ONCE(rq->engine);
>>> +	spin_lock_irq(&locked->sched_engine->lock);
>>> +	while (unlikely(locked != (engine = READ_ONCE(rq->engine)))) {
>>> +		spin_unlock(&locked->sched_engine->lock);
>>> +		spin_lock(&engine->sched_engine->lock);
>>> +		locked = engine;
>>> +	}
>>> +	list_del_init(&rq->sched.link);
>>> +
>>> +	clear_bit(I915_FENCE_FLAG_PQUEUE, &rq->fence.flags);
>>> +	clear_bit(I915_FENCE_FLAG_HOLD, &rq->fence.flags);
>>> +
>>> +	/* Prevent further __await_execution() registering a cb, then flush */
>>> +	set_bit(I915_FENCE_FLAG_ACTIVE, &rq->fence.flags);
>>> +
>>> +	spin_unlock_irq(&locked->sched_engine->lock);
>>> +
>>> +	i915_request_notify_execute_cb_imm(rq);
>>> +}
>>> +
>>>    static bool can_preempt(struct intel_engine_cs *engine)
>>>    {
>>>    	if (GRAPHICS_VER(engine->i915) > 8)
>>> @@ -3218,6 +3254,8 @@ logical_ring_default_vfuncs(struct intel_engine_cs *engine)
>>>    	engine->cops = &execlists_context_ops;
>>>    	engine->request_alloc = execlists_request_alloc;
>>>    	engine->bump_serial = execlist_bump_serial;
>>> +	engine->add_active_request = add_to_engine;
>>> +	engine->remove_active_request = remove_from_engine;
>>>    	engine->reset.prepare = execlists_reset_prepare;
>>>    	engine->reset.rewind = execlists_reset_rewind;
>>> @@ -3912,6 +3950,8 @@ execlists_create_virtual(struct intel_engine_cs **siblings, unsigned int count)
>>>    			 "v%dx%d", ve->base.class, count);
>>>    		ve->base.context_size = sibling->context_size;
>>> +		ve->base.add_active_request = sibling->add_active_request;
>>> +		ve->base.remove_active_request = sibling->remove_active_request;
>>>    		ve->base.emit_bb_start = sibling->emit_bb_start;
>>>    		ve->base.emit_flush = sibling->emit_flush;
>>>    		ve->base.emit_init_breadcrumb = sibling->emit_init_breadcrumb;
>>> diff --git a/drivers/gpu/drm/i915/gt/intel_gt_pm.c b/drivers/gpu/drm/i915/gt/intel_gt_pm.c
>>> index aef3084e8b16..463a6ae605a0 100644
>>> --- a/drivers/gpu/drm/i915/gt/intel_gt_pm.c
>>> +++ b/drivers/gpu/drm/i915/gt/intel_gt_pm.c
>>> @@ -174,8 +174,6 @@ static void gt_sanitize(struct intel_gt *gt, bool force)
>>>    	if (intel_gt_is_wedged(gt))
>>>    		intel_gt_unset_wedged(gt);
>>> -	intel_uc_sanitize(&gt->uc);
>>> -
>>>    	for_each_engine(engine, gt, id)
>>>    		if (engine->reset.prepare)
>>>    			engine->reset.prepare(engine);
>>> @@ -191,6 +189,8 @@ static void gt_sanitize(struct intel_gt *gt, bool force)
>>>    			__intel_engine_reset(engine, false);
>>>    	}
>>> +	intel_uc_reset(&gt->uc, false);
>>> +
>>>    	for_each_engine(engine, gt, id)
>>>    		if (engine->reset.finish)
>>>    			engine->reset.finish(engine);
>>> @@ -243,6 +243,8 @@ int intel_gt_resume(struct intel_gt *gt)
>>>    		goto err_wedged;
>>>    	}
>>> +	intel_uc_reset_finish(&gt->uc);
>>> +
>>>    	intel_rps_enable(&gt->rps);
>>>    	intel_llc_enable(&gt->llc);
>>> diff --git a/drivers/gpu/drm/i915/gt/intel_reset.c b/drivers/gpu/drm/i915/gt/intel_reset.c
>>> index 72251638d4ea..2987282dff6d 100644
>>> --- a/drivers/gpu/drm/i915/gt/intel_reset.c
>>> +++ b/drivers/gpu/drm/i915/gt/intel_reset.c
>>> @@ -826,6 +826,8 @@ static int gt_reset(struct intel_gt *gt, intel_engine_mask_t stalled_mask)
>>>    		__intel_engine_reset(engine, stalled_mask & engine->mask);
>>>    	local_bh_enable();
>>> +	intel_uc_reset(&gt->uc, true);
>>> +
>>>    	intel_ggtt_restore_fences(gt->ggtt);
>>>    	return err;
>>> @@ -850,6 +852,8 @@ static void reset_finish(struct intel_gt *gt, intel_engine_mask_t awake)
>>>    		if (awake & engine->mask)
>>>    			intel_engine_pm_put(engine);
>>>    	}
>>> +
>>> +	intel_uc_reset_finish(&gt->uc);
>>>    }
>>>    static void nop_submit_request(struct i915_request *request)
>>> @@ -903,6 +907,7 @@ static void __intel_gt_set_wedged(struct intel_gt *gt)
>>>    	for_each_engine(engine, gt, id)
>>>    		if (engine->reset.cancel)
>>>    			engine->reset.cancel(engine);
>>> +	intel_uc_cancel_requests(&gt->uc);
>>>    	local_bh_enable();
>>>    	reset_finish(gt, awake);
>>> @@ -1191,6 +1196,9 @@ int __intel_engine_reset_bh(struct intel_engine_cs *engine, const char *msg)
>>>    	ENGINE_TRACE(engine, "flags=%lx\n", gt->reset.flags);
>>>    	GEM_BUG_ON(!test_bit(I915_RESET_ENGINE + engine->id, &gt->reset.flags));
>>> +	if (intel_engine_uses_guc(engine))
>>> +		return -ENODEV;
>>> +
>>>    	if (!intel_engine_pm_get_if_awake(engine))
>>>    		return 0;
>>> @@ -1201,13 +1209,10 @@ int __intel_engine_reset_bh(struct intel_engine_cs *engine, const char *msg)
>>>    			   "Resetting %s for %s\n", engine->name, msg);
>>>    	atomic_inc(&engine->i915->gpu_error.reset_engine_count[engine->uabi_class]);
>>> -	if (intel_engine_uses_guc(engine))
>>> -		ret = intel_guc_reset_engine(&engine->gt->uc.guc, engine);
>>> -	else
>>> -		ret = intel_gt_reset_engine(engine);
>>> +	ret = intel_gt_reset_engine(engine);
>>>    	if (ret) {
>>>    		/* If we fail here, we expect to fallback to a global reset */
>>> -		ENGINE_TRACE(engine, "Failed to reset, err: %d\n", ret);
>>> +		ENGINE_TRACE(engine, "Failed to reset %s, err: %d\n", engine->name, ret);
>>>    		goto out;
>>>    	}
>>> @@ -1341,7 +1346,8 @@ void intel_gt_handle_error(struct intel_gt *gt,
>>>    	 * Try engine reset when available. We fall back to full reset if
>>>    	 * single reset fails.
>>>    	 */
>>> -	if (intel_has_reset_engine(gt) && !intel_gt_is_wedged(gt)) {
>>> +	if (!intel_uc_uses_guc_submission(&gt->uc) &&
>>> +	    intel_has_reset_engine(gt) && !intel_gt_is_wedged(gt)) {
>>>    		local_bh_disable();
>>>    		for_each_engine_masked(engine, gt, engine_mask, tmp) {
>>>    			BUILD_BUG_ON(I915_RESET_MODESET >= I915_RESET_ENGINE);
>>> diff --git a/drivers/gpu/drm/i915/gt/intel_ring_submission.c b/drivers/gpu/drm/i915/gt/intel_ring_submission.c
>>> index e1506b280df1..99dcdc8fba12 100644
>>> --- a/drivers/gpu/drm/i915/gt/intel_ring_submission.c
>>> +++ b/drivers/gpu/drm/i915/gt/intel_ring_submission.c
>>> @@ -1049,6 +1049,25 @@ static void ring_bump_serial(struct intel_engine_cs *engine)
>>>    	engine->serial++;
>>>    }
>>> +static void add_to_engine(struct i915_request *rq)
>>> +{
>>> +	lockdep_assert_held(&rq->engine->sched_engine->lock);
>>> +	list_move_tail(&rq->sched.link, &rq->engine->sched_engine->requests);
>>> +}
>>> +
>>> +static void remove_from_engine(struct i915_request *rq)
>>> +{
>>> +	spin_lock_irq(&rq->engine->sched_engine->lock);
>>> +	list_del_init(&rq->sched.link);
>>> +
>>> +	/* Prevent further __await_execution() registering a cb, then flush */
>>> +	set_bit(I915_FENCE_FLAG_ACTIVE, &rq->fence.flags);
>>> +
>>> +	spin_unlock_irq(&rq->engine->sched_engine->lock);
>>> +
>>> +	i915_request_notify_execute_cb_imm(rq);
>>> +}
>>> +
>>>    static void setup_common(struct intel_engine_cs *engine)
>>>    {
>>>    	struct drm_i915_private *i915 = engine->i915;
>>> @@ -1066,6 +1085,9 @@ static void setup_common(struct intel_engine_cs *engine)
>>>    	engine->reset.cancel = reset_cancel;
>>>    	engine->reset.finish = reset_finish;
>>> +	engine->add_active_request = add_to_engine;
>>> +	engine->remove_active_request = remove_from_engine;
>>> +
>>>    	engine->cops = &ring_context_ops;
>>>    	engine->request_alloc = ring_request_alloc;
>>>    	engine->bump_serial = ring_bump_serial;
>>> diff --git a/drivers/gpu/drm/i915/gt/mock_engine.c b/drivers/gpu/drm/i915/gt/mock_engine.c
>>> index fc5a65ab1937..c12ff3a75ce6 100644
>>> --- a/drivers/gpu/drm/i915/gt/mock_engine.c
>>> +++ b/drivers/gpu/drm/i915/gt/mock_engine.c
>>> @@ -235,6 +235,35 @@ static void mock_submit_request(struct i915_request *request)
>>>    	spin_unlock_irqrestore(&engine->hw_lock, flags);
>>>    }
>>> +static void mock_add_to_engine(struct i915_request *rq)
>>> +{
>>> +	lockdep_assert_held(&rq->engine->sched_engine->lock);
>>> +	list_move_tail(&rq->sched.link, &rq->engine->sched_engine->requests);
>>> +}
>>> +
>>> +static void mock_remove_from_engine(struct i915_request *rq)
>>> +{
>>> +	struct intel_engine_cs *engine, *locked;
>>> +
>>> +	/*
>>> +	 * Virtual engines complicate acquiring the engine timeline lock,
>>> +	 * as their rq->engine pointer is not stable until under that
>>> +	 * engine lock. The simple ploy we use is to take the lock then
>>> +	 * check that the rq still belongs to the newly locked engine.
>>> +	 */
>>> +
>>> +	locked = READ_ONCE(rq->engine);
>>> +	spin_lock_irq(&locked->sched_engine->lock);
>>> +	while (unlikely(locked != (engine = READ_ONCE(rq->engine)))) {
>>> +		spin_unlock(&locked->sched_engine->lock);
>>> +		spin_lock(&engine->sched_engine->lock);
>>> +		locked = engine;
>>> +	}
>>> +	list_del_init(&rq->sched.link);
>>> +	spin_unlock_irq(&locked->sched_engine->lock);
>>> +}
>>> +
>>> +
>>>    static void mock_reset_prepare(struct intel_engine_cs *engine)
>>>    {
>>>    }
>>> @@ -327,6 +356,8 @@ struct intel_engine_cs *mock_engine(struct drm_i915_private *i915,
>>>    	engine->base.emit_flush = mock_emit_flush;
>>>    	engine->base.emit_fini_breadcrumb = mock_emit_breadcrumb;
>>>    	engine->base.submit_request = mock_submit_request;
>>> +	engine->base.add_active_request = mock_add_to_engine;
>>> +	engine->base.remove_active_request = mock_remove_from_engine;
>>>    	engine->base.reset.prepare = mock_reset_prepare;
>>>    	engine->base.reset.rewind = mock_reset_rewind;
>>> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc.c b/drivers/gpu/drm/i915/gt/uc/intel_guc.c
>>> index 6661dcb02239..9b09395b998f 100644
>>> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc.c
>>> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc.c
>>> @@ -572,19 +572,6 @@ int intel_guc_suspend(struct intel_guc *guc)
>>>    	return 0;
>>>    }
>>> -/**
>>> - * intel_guc_reset_engine() - ask GuC to reset an engine
>>> - * @guc:	intel_guc structure
>>> - * @engine:	engine to be reset
>>> - */
>>> -int intel_guc_reset_engine(struct intel_guc *guc,
>>> -			   struct intel_engine_cs *engine)
>>> -{
>>> -	/* XXX: to be implemented with submission interface rework */
>>> -
>>> -	return -ENODEV;
>>> -}
>>> -
>>>    /**
>>>     * intel_guc_resume() - notify GuC resuming from suspend state
>>>     * @guc:	the guc
>>> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc.h b/drivers/gpu/drm/i915/gt/uc/intel_guc.h
>>> index 22eb1e9cca41..40c9868762d7 100644
>>> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc.h
>>> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc.h
>>> @@ -242,14 +242,16 @@ static inline void intel_guc_disable_msg(struct intel_guc *guc, u32 mask)
>>>    int intel_guc_wait_for_idle(struct intel_guc *guc, long timeout);
>>> -int intel_guc_reset_engine(struct intel_guc *guc,
>>> -			   struct intel_engine_cs *engine);
>>> -
>>>    int intel_guc_deregister_done_process_msg(struct intel_guc *guc,
>>>    					  const u32 *msg, u32 len);
>>>    int intel_guc_sched_done_process_msg(struct intel_guc *guc,
>>>    				     const u32 *msg, u32 len);
>>> +void intel_guc_submission_reset_prepare(struct intel_guc *guc);
>>> +void intel_guc_submission_reset(struct intel_guc *guc, bool stalled);
>>> +void intel_guc_submission_reset_finish(struct intel_guc *guc);
>>> +void intel_guc_submission_cancel_requests(struct intel_guc *guc);
>>> +
>>>    void intel_guc_load_status(struct intel_guc *guc, struct drm_printer *p);
>>>    #endif
>>> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
>>> index 83058df5ba01..b8c894ad8caf 100644
>>> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
>>> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
>>> @@ -141,7 +141,7 @@ context_wait_for_deregister_to_register(struct intel_context *ce)
>>>    static inline void
>>>    set_context_wait_for_deregister_to_register(struct intel_context *ce)
>>>    {
>>> -	/* Only should be called from guc_lrc_desc_pin() */
>>> +	/* Only should be called from guc_lrc_desc_pin() without lock */
>>>    	ce->guc_state.sched_state |=
>>>    		SCHED_STATE_WAIT_FOR_DEREGISTER_TO_REGISTER;
>>>    }
>>> @@ -241,15 +241,31 @@ static int guc_lrc_desc_pool_create(struct intel_guc *guc)
>>>    static void guc_lrc_desc_pool_destroy(struct intel_guc *guc)
>>>    {
>>> +	guc->lrc_desc_pool_vaddr = NULL;
>>>    	i915_vma_unpin_and_release(&guc->lrc_desc_pool, I915_VMA_RELEASE_MAP);
>>>    }
>>> +static inline bool guc_submission_initialized(struct intel_guc *guc)
>>> +{
>>> +	return guc->lrc_desc_pool_vaddr != NULL;
>>> +}
>>> +
>>>    static inline void reset_lrc_desc(struct intel_guc *guc, u32 id)
>>>    {
>>> -	struct guc_lrc_desc *desc = __get_lrc_desc(guc, id);
>>> +	if (likely(guc_submission_initialized(guc))) {
>>> +		struct guc_lrc_desc *desc = __get_lrc_desc(guc, id);
>>> +		unsigned long flags;
>>> -	memset(desc, 0, sizeof(*desc));
>>> -	xa_erase_irq(&guc->context_lookup, id);
>>> +		memset(desc, 0, sizeof(*desc));
>>> +
>>> +		/*
>>> +		 * xarray API doesn't have xa_erase_irqsave wrapper, so calling
>>> +		 * the lower level functions directly.
>>> +		 */
>>> +		xa_lock_irqsave(&guc->context_lookup, flags);
>>> +		__xa_erase(&guc->context_lookup, id);
>>> +		xa_unlock_irqrestore(&guc->context_lookup, flags);
>>> +	}
>>>    }
>>>    static inline bool lrc_desc_registered(struct intel_guc *guc, u32 id)
>>> @@ -260,7 +276,15 @@ static inline bool lrc_desc_registered(struct intel_guc *guc, u32 id)
>>>    static inline void set_lrc_desc_registered(struct intel_guc *guc, u32 id,
>>>    					   struct intel_context *ce)
>>>    {
>>> -	xa_store_irq(&guc->context_lookup, id, ce, GFP_ATOMIC);
>>> +	unsigned long flags;
>>> +
>>> +	/*
>>> +	 * xarray API doesn't have xa_save_irqsave wrapper, so calling the
>>> +	 * lower level functions directly.
>>> +	 */
>>> +	xa_lock_irqsave(&guc->context_lookup, flags);
>>> +	__xa_store(&guc->context_lookup, id, ce, GFP_ATOMIC);
>>> +	xa_unlock_irqrestore(&guc->context_lookup, flags);
>>>    }
>>>    static int guc_submission_busy_loop(struct intel_guc* guc,
>>> @@ -331,6 +355,8 @@ int intel_guc_wait_for_idle(struct intel_guc *guc, long timeout)
>>>    					interruptible, timeout);
>>>    }
>>> +static int guc_lrc_desc_pin(struct intel_context *ce, bool loop);
>>> +
>>>    static int guc_add_request(struct intel_guc *guc, struct i915_request *rq)
>>>    {
>>>    	int err;
>>> @@ -338,11 +364,22 @@ static int guc_add_request(struct intel_guc *guc, struct i915_request *rq)
>>>    	u32 action[3];
>>>    	int len = 0;
>>>    	u32 g2h_len_dw = 0;
>>> -	bool enabled = context_enabled(ce);
>>> +	bool enabled;
>>>    	GEM_BUG_ON(!atomic_read(&ce->guc_id_ref));
>>>    	GEM_BUG_ON(context_guc_id_invalid(ce));
>>> +	/*
>>> +	 * Corner case where the GuC firmware was blown away and reloaded while
>>> +	 * this context was pinned.
>>> +	 */
>>> +	if (unlikely(!lrc_desc_registered(guc, ce->guc_id))) {
>>> +		err = guc_lrc_desc_pin(ce, false);
>>> +		if (unlikely(err))
>>> +			goto out;
>>> +	}
>>> +	enabled = context_enabled(ce);
>>> +
>>>    	if (!enabled) {
>>>    		action[len++] = INTEL_GUC_ACTION_SCHED_CONTEXT_MODE_SET;
>>>    		action[len++] = ce->guc_id;
>>> @@ -365,6 +402,7 @@ static int guc_add_request(struct intel_guc *guc, struct i915_request *rq)
>>>    		intel_context_put(ce);
>>>    	}
>>> +out:
>>>    	return err;
>>>    }
>>> @@ -419,15 +457,10 @@ static int guc_dequeue_one_context(struct intel_guc *guc)
>>>    	if (submit) {
>>>    		guc_set_lrc_tail(last);
>>>    resubmit:
>>> -		/*
>>> -		 * We only check for -EBUSY here even though it is possible for
>>> -		 * -EDEADLK to be returned. If -EDEADLK is returned, the GuC has
>>> -		 * died and a full GPU needs to be done. The hangcheck will
>>> -		 * eventually detect that the GuC has died and trigger this
>>> -		 * reset so no need to handle -EDEADLK here.
>>> -		 */
>>>    		ret = guc_add_request(guc, last);
>>> -		if (ret == -EBUSY) {
>>> +		if (unlikely(ret == -EIO))
>>> +			goto deadlk;
>>> +		else if (ret == -EBUSY) {
>>>    			tasklet_schedule(&sched_engine->tasklet);
>>>    			guc->stalled_request = last;
>>>    			return false;
>>> @@ -437,6 +470,11 @@ static int guc_dequeue_one_context(struct intel_guc *guc)
>>>    	guc->stalled_request = NULL;
>>>    	return submit;
>>> +
>>> +deadlk:
>>> +	sched_engine->tasklet.callback = NULL;
>>> +	tasklet_disable_nosync(&sched_engine->tasklet);
>>> +	return false;
>>>    }
>>>    static void guc_submission_tasklet(struct tasklet_struct *t)
>>> @@ -463,27 +501,165 @@ static void cs_irq_handler(struct intel_engine_cs *engine, u16 iir)
>>>    		intel_engine_signal_breadcrumbs(engine);
>>>    }
>>> -static void guc_reset_prepare(struct intel_engine_cs *engine)
>>> +static void __guc_context_destroy(struct intel_context *ce);
>>> +static void release_guc_id(struct intel_guc *guc, struct intel_context *ce);
>>> +static void guc_signal_context_fence(struct intel_context *ce);
>>> +
>>> +static void scrub_guc_desc_for_outstanding_g2h(struct intel_guc *guc)
>>> +{
>>> +	struct intel_context *ce;
>>> +	unsigned long index, flags;
>>> +	bool pending_disable, pending_enable, deregister, destroyed;
>>> +
>>> +	xa_for_each(&guc->context_lookup, index, ce) {
>>> +		/* Flush context */
>>> +		spin_lock_irqsave(&ce->guc_state.lock, flags);
>>> +		spin_unlock_irqrestore(&ce->guc_state.lock, flags);
>>> +
>>> +		/*
>>> +		 * Once we are at this point submission_disabled() is guaranteed
>>> +		 * to visible to all callers who set the below flags (see above
>>> +		 * flush and flushes in reset_prepare). If submission_disabled()
>>> +		 * is set, the caller shouldn't set these flags.
>>> +		 */
>>> +
>>> +		destroyed = context_destroyed(ce);
>>> +		pending_enable = context_pending_enable(ce);
>>> +		pending_disable = context_pending_disable(ce);
>>> +		deregister = context_wait_for_deregister_to_register(ce);
>>> +		init_sched_state(ce);
>>> +
>>> +		if (pending_enable || destroyed || deregister) {
>>> +			atomic_dec(&guc->outstanding_submission_g2h);
>>> +			if (deregister)
>>> +				guc_signal_context_fence(ce);
>>> +			if (destroyed) {
>>> +				release_guc_id(guc, ce);
>>> +				__guc_context_destroy(ce);
>>> +			}
>>> +			if (pending_enable|| deregister)
>>> +				intel_context_put(ce);
>>> +		}
>>> +
>>> +		/* Not mutualy exclusive with above if statement. */
>>> +		if (pending_disable) {
>>> +			guc_signal_context_fence(ce);
>>> +			intel_context_sched_disable_unpin(ce);
>>> +			atomic_dec(&guc->outstanding_submission_g2h);
>>> +			intel_context_put(ce);
>>> +		}
>>> +	}
>>> +}
>>> +
>>> +static inline bool
>>> +submission_disabled(struct intel_guc *guc)
>>> +{
>>> +	struct i915_sched_engine * const sched_engine = guc->sched_engine;
>>> +
>>> +	return unlikely(!__tasklet_is_enabled(&sched_engine->tasklet));
>>> +}
>>> +
>>> +static void disable_submission(struct intel_guc *guc)
>>> +{
>>> +	struct i915_sched_engine * const sched_engine = guc->sched_engine;
>>> +
>>> +	if (__tasklet_is_enabled(&sched_engine->tasklet)) {
>>> +		GEM_BUG_ON(!guc->ct.enabled);
>>> +		__tasklet_disable_sync_once(&sched_engine->tasklet);
>>> +		sched_engine->tasklet.callback = NULL;
>>> +	}
>>> +}
>>> +
>>> +static void enable_submission(struct intel_guc *guc)
>>> +{
>>> +	struct i915_sched_engine * const sched_engine = guc->sched_engine;
>>> +	unsigned long flags;
>>> +
>>> +	spin_lock_irqsave(&guc->sched_engine->lock, flags);
>>> +	sched_engine->tasklet.callback = guc_submission_tasklet;
>>> +	wmb();
>>> +	if (!__tasklet_is_enabled(&sched_engine->tasklet) &&
>>> +	    __tasklet_enable(&sched_engine->tasklet)) {
>>> +		GEM_BUG_ON(!guc->ct.enabled);
>>> +
>>> +		/* And kick in case we missed a new request submission. */
>>> +		tasklet_hi_schedule(&sched_engine->tasklet);
>>> +	}
>>> +	spin_unlock_irqrestore(&guc->sched_engine->lock, flags);
>>> +}
>>> +
>>> +static void guc_flush_submissions(struct intel_guc *guc)
>>>    {
>>> -	ENGINE_TRACE(engine, "\n");
>>> +	struct i915_sched_engine * const sched_engine = guc->sched_engine;
>>> +	unsigned long flags;
>>> +
>>> +	spin_lock_irqsave(&sched_engine->lock, flags);
>>> +	spin_unlock_irqrestore(&sched_engine->lock, flags);
>>> +}
>>> +
>>> +void intel_guc_submission_reset_prepare(struct intel_guc *guc)
>>> +{
>>> +	int i;
>>> +
>>> +	if (unlikely(!guc_submission_initialized(guc)))
>>> +		/* Reset called during driver load? GuC not yet initialised! */
>>> +		return;
>>> +
>>> +	disable_submission(guc);
>>> +	guc->interrupts.disable(guc);
>>> +
>>> +	/* Flush IRQ handler */
>>> +	spin_lock_irq(&guc_to_gt(guc)->irq_lock);
>>> +	spin_unlock_irq(&guc_to_gt(guc)->irq_lock);
>>> +
>>> +	guc_flush_submissions(guc);
>>>    	/*
>>> -	 * Prevent request submission to the hardware until we have
>>> -	 * completed the reset in i915_gem_reset_finish(). If a request
>>> -	 * is completed by one engine, it may then queue a request
>>> -	 * to a second via its execlists->tasklet *just* as we are
>>> -	 * calling engine->init_hw() and also writing the ELSP.
>>> -	 * Turning off the execlists->tasklet until the reset is over
>>> -	 * prevents the race.
>>> -	 */
>>> -	__tasklet_disable_sync_once(&engine->sched_engine->tasklet);
>>> +	 * Handle any outstanding G2Hs before reset. Call IRQ handler directly
>>> +	 * each pass as interrupt have been disabled. We always scrub for
>>> +	 * outstanding G2H as it is possible for outstanding_submission_g2h to
>>> +	 * be incremented after the context state update.
>>> + 	 */
>>> +	for (i = 0; i < 4 && atomic_read(&guc->outstanding_submission_g2h); ++i) {
>>> +		intel_guc_to_host_event_handler(guc);
>>> +#define wait_for_reset(guc, wait_var) \
>>> +		guc_wait_for_pending_msg(guc, wait_var, false, (HZ / 20))
>>> +		do {
>>> +			wait_for_reset(guc, &guc->outstanding_submission_g2h);
>>> +		} while (!list_empty(&guc->ct.requests.incoming));
>>> +	}
>>> +	scrub_guc_desc_for_outstanding_g2h(guc);
>>>    }
>>> -static void guc_reset_state(struct intel_context *ce,
>>> -			    struct intel_engine_cs *engine,
>>> -			    u32 head,
>>> -			    bool scrub)
>>> +static struct intel_engine_cs *
>>> +guc_virtual_get_sibling(struct intel_engine_cs *ve, unsigned int sibling)
>>>    {
>>> +	struct intel_engine_cs *engine;
>>> +	intel_engine_mask_t tmp, mask = ve->mask;
>>> +	unsigned int num_siblings = 0;
>>> +
>>> +	for_each_engine_masked(engine, ve->gt, mask, tmp)
>>> +		if (num_siblings++ == sibling)
>>> +			return engine;
>>> +
>>> +	return NULL;
>>> +}
>>> +
>>> +static inline struct intel_engine_cs *
>>> +__context_to_physical_engine(struct intel_context *ce)
>>> +{
>>> +	struct intel_engine_cs *engine = ce->engine;
>>> +
>>> +	if (intel_engine_is_virtual(engine))
>>> +		engine = guc_virtual_get_sibling(engine, 0);
>>> +
>>> +	return engine;
>>> +}
>>> +
>>> +static void guc_reset_state(struct intel_context *ce, u32 head, bool scrub)
>>> +{
>>> +	struct intel_engine_cs *engine = __context_to_physical_engine(ce);
>>> +
>>>    	GEM_BUG_ON(!intel_context_is_pinned(ce));
>>>    	/*
>>> @@ -501,42 +677,147 @@ static void guc_reset_state(struct intel_context *ce,
>>>    	lrc_update_regs(ce, engine, head);
>>>    }
>>> -static void guc_reset_rewind(struct intel_engine_cs *engine, bool stalled)
>>> +static void guc_reset_nop(struct intel_engine_cs *engine)
>>>    {
>>> -	struct intel_engine_execlists * const execlists = &engine->execlists;
>>> -	struct i915_request *rq;
>>> +}
>>> +
>>> +static void guc_rewind_nop(struct intel_engine_cs *engine, bool stalled)
>>> +{
>>> +}
>>> +
>>> +static void
>>> +__unwind_incomplete_requests(struct intel_context *ce)
>>> +{
>>> +	struct i915_request *rq, *rn;
>>> +	struct list_head *pl;
>>> +	int prio = I915_PRIORITY_INVALID;
>>> +	struct i915_sched_engine * const sched_engine =
>>> +		ce->engine->sched_engine;
>>>    	unsigned long flags;
>>> -	spin_lock_irqsave(&engine->sched_engine->lock, flags);
>>> +	spin_lock_irqsave(&sched_engine->lock, flags);
>>> +	spin_lock(&ce->guc_active.lock);
>>> +	list_for_each_entry_safe(rq, rn,
>>> +				 &ce->guc_active.requests,
>>> +				 sched.link) {
>>> +		if (i915_request_completed(rq))
>>> +			continue;
>>> +
>>> +		list_del_init(&rq->sched.link);
>>> +		spin_unlock(&ce->guc_active.lock);
>>> +
>>> +		__i915_request_unsubmit(rq);
>>> +
>>> +		/* Push the request back into the queue for later resubmission. */
>>> +		GEM_BUG_ON(rq_prio(rq) == I915_PRIORITY_INVALID);
>>> +		if (rq_prio(rq) != prio) {
>>> +			prio = rq_prio(rq);
>>> +			pl = i915_sched_lookup_priolist(sched_engine, prio);
>>> +		}
>>> +		GEM_BUG_ON(i915_sched_engine_is_empty(sched_engine));
>>> +
>>> +		list_add_tail(&rq->sched.link, pl);
>>> +		set_bit(I915_FENCE_FLAG_PQUEUE, &rq->fence.flags);
>>> -	/* Push back any incomplete requests for replay after the reset. */
>>> -	rq = execlists_unwind_incomplete_requests(execlists);
>>> -	if (!rq)
>>> -		goto out_unlock;
>>> +		spin_lock(&ce->guc_active.lock);
>>> +	}
>>> +	spin_unlock(&ce->guc_active.lock);
>>> +	spin_unlock_irqrestore(&sched_engine->lock, flags);
>>> +}
>>> +
>>> +static struct i915_request *context_find_active_request(struct intel_context *ce)
>>> +{
>>> +	struct i915_request *rq, *active = NULL;
>>> +	unsigned long flags;
>>> +
>>> +	spin_lock_irqsave(&ce->guc_active.lock, flags);
>>> +	list_for_each_entry_reverse(rq, &ce->guc_active.requests,
>>> +				    sched.link) {
>>> +		if (i915_request_completed(rq))
>>> +			break;
>>> +
>>> +		active = rq;
>>> +	}
>>> +	spin_unlock_irqrestore(&ce->guc_active.lock, flags);
>>> +
>>> +	return active;
>>> +}
>>> +
>>> +static void __guc_reset_context(struct intel_context *ce, bool stalled)
>>> +{
>>> +	struct i915_request *rq;
>>> +	u32 head;
>>> +
>>> +	/*
>>> +	 * GuC will implicitly mark the context as non-schedulable
>>> +	 * when it sends the reset notification. Make sure our state
>>> +	 * reflects this change. The context will be marked enabled
>>> +	 * on resubmission.
>>> +	 */
>>> +	clr_context_enabled(ce);
>>> +
>>> +	rq = context_find_active_request(ce);
>>> +	if (!rq) {
>>> +		head = ce->ring->tail;
>>> +		stalled = false;
>>> +		goto out_replay;
>>> +	}
>>>    	if (!i915_request_started(rq))
>>>    		stalled = false;
>>> +	GEM_BUG_ON(i915_active_is_idle(&ce->active));
>>> +	head = intel_ring_wrap(ce->ring, rq->head);
>>>    	__i915_request_reset(rq, stalled);
>>> -	guc_reset_state(rq->context, engine, rq->head, stalled);
>>> -out_unlock:
>>> -	spin_unlock_irqrestore(&engine->sched_engine->lock, flags);
>>> +out_replay:
>>> +	guc_reset_state(ce, head, stalled);
>>> +	__unwind_incomplete_requests(ce);
>>>    }
>>> -static void guc_reset_cancel(struct intel_engine_cs *engine)
>>> +void intel_guc_submission_reset(struct intel_guc *guc, bool stalled)
>>> +{
>>> +	struct intel_context *ce;
>>> +	unsigned long index;
>>> +
>>> +	if (unlikely(!guc_submission_initialized(guc)))
>>> +		/* Reset called during driver load? GuC not yet initialised! */
>>> +		return;
>>> +
>>> +	xa_for_each(&guc->context_lookup, index, ce)
>>> +		if (intel_context_is_pinned(ce))
>>> +			__guc_reset_context(ce, stalled);
>>> +
>>> +	/* GuC is blown away, drop all references to contexts */
>>> +	xa_destroy(&guc->context_lookup);
>>> +}
>>> +
>>> +static void guc_cancel_context_requests(struct intel_context *ce)
>>> +{
>>> +	struct i915_sched_engine *sched_engine = ce_to_guc(ce)->sched_engine;
>>> +	struct i915_request *rq;
>>> +	unsigned long flags;
>>> +
>>> +	/* Mark all executing requests as skipped. */
>>> +	spin_lock_irqsave(&sched_engine->lock, flags);
>>> +	spin_lock(&ce->guc_active.lock);
>>> +	list_for_each_entry(rq, &ce->guc_active.requests, sched.link)
>>> +		i915_request_put(i915_request_mark_eio(rq));
>>> +	spin_unlock(&ce->guc_active.lock);
>>> +	spin_unlock_irqrestore(&sched_engine->lock, flags);
>>> +}
>>> +
>>> +static void
>>> +guc_cancel_sched_engine_requests(struct i915_sched_engine *sched_engine)
>>>    {
>>> -	struct i915_sched_engine * const sched_engine = engine->sched_engine;
>>>    	struct i915_request *rq, *rn;
>>>    	struct rb_node *rb;
>>>    	unsigned long flags;
>>>    	/* Can be called during boot if GuC fails to load */
>>> -	if (!engine->gt)
>>> +	if (!sched_engine)
>>>    		return;
>>> -	ENGINE_TRACE(engine, "\n");
>>> -
>>>    	/*
>>>    	 * Before we call engine->cancel_requests(), we should have exclusive
>>>    	 * access to the submission state. This is arranged for us by the
>>> @@ -553,21 +834,16 @@ static void guc_reset_cancel(struct intel_engine_cs *engine)
>>>    	 */
>>>    	spin_lock_irqsave(&sched_engine->lock, flags);
>>> -	/* Mark all executing requests as skipped. */
>>> -	list_for_each_entry(rq, &sched_engine->requests, sched.link) {
>>> -		i915_request_set_error_once(rq, -EIO);
>>> -		i915_request_mark_complete(rq);
>>> -	}
>>> -
>>>    	/* Flush the queued requests to the timeline list (for retiring). */
>>>    	while ((rb = rb_first_cached(&sched_engine->queue))) {
>>>    		struct i915_priolist *p = to_priolist(rb);
>>>    		priolist_for_each_request_consume(rq, rn, p) {
>>>    			list_del_init(&rq->sched.link);
>>> +
>>>    			__i915_request_submit(rq);
>>> -			dma_fence_set_error(&rq->fence, -EIO);
>>> -			i915_request_mark_complete(rq);
>>> +
>>> +			i915_request_put(i915_request_mark_eio(rq));
>>>    		}
>>>    		rb_erase_cached(&p->node, &sched_engine->queue);
>>> @@ -582,14 +858,38 @@ static void guc_reset_cancel(struct intel_engine_cs *engine)
>>>    	spin_unlock_irqrestore(&sched_engine->lock, flags);
>>>    }
>>> -static void guc_reset_finish(struct intel_engine_cs *engine)
>>> +void intel_guc_submission_cancel_requests(struct intel_guc *guc)
>>>    {
>>> -	if (__tasklet_enable(&engine->sched_engine->tasklet))
>>> -		/* And kick in case we missed a new request submission. */
>>> -		tasklet_hi_schedule(&engine->sched_engine->tasklet);
>>> +	struct intel_context *ce;
>>> +	unsigned long index;
>>> +
>>> +	xa_for_each(&guc->context_lookup, index, ce)
>>> +		if (intel_context_is_pinned(ce))
>>> +			guc_cancel_context_requests(ce);
>>> -	ENGINE_TRACE(engine, "depth->%d\n",
>>> -		     atomic_read(&engine->sched_engine->tasklet.count));
>>> +	guc_cancel_sched_engine_requests(guc->sched_engine);
>>> +
>>> +	/* GuC is blown away, drop all references to contexts */
>>> +	xa_destroy(&guc->context_lookup);
>>> +}
>>> +
>>> +void intel_guc_submission_reset_finish(struct intel_guc *guc)
>>> +{
>>> +	/* Reset called during driver load or during wedge? */
>>> +	if (unlikely(!guc_submission_initialized(guc) ||
>>> +		     test_bit(I915_WEDGED, &guc_to_gt(guc)->reset.flags)))
>>> +		return;
>>> +
>>> +	/*
>>> +	 * Technically possible for either of these values to be non-zero here,
>>> +	 * but very unlikely + harmless. Regardless let's add a warn so we can
>>> +	 * see in CI if this happens frequently / a precursor to taking down the
>>> +	 * machine.
>>> +	 */
>>> +	GEM_WARN_ON(atomic_read(&guc->outstanding_submission_g2h));
>>> +	atomic_set(&guc->outstanding_submission_g2h, 0);
>>> +
>>> +	enable_submission(guc);
>>>    }
>>>    /*
>>> @@ -656,6 +956,9 @@ static int guc_bypass_tasklet_submit(struct intel_guc *guc,
>>>    	else
>>>    		trace_i915_request_guc_submit(rq);
>>> +	if (unlikely(ret == -EIO))
>>> +		disable_submission(guc);
>>> +
>>>    	return ret;
>>>    }
>>> @@ -668,7 +971,8 @@ static void guc_submit_request(struct i915_request *rq)
>>>    	/* Will be called from irq-context when using foreign fences. */
>>>    	spin_lock_irqsave(&sched_engine->lock, flags);
>>> -	if (guc->stalled_request || !i915_sched_engine_is_empty(sched_engine))
>>> +	if (submission_disabled(guc) || guc->stalled_request ||
>>> +	    !i915_sched_engine_is_empty(sched_engine))
>>>    		queue_request(sched_engine, rq, rq_prio(rq));
>>>    	else if (guc_bypass_tasklet_submit(guc, rq) == -EBUSY)
>>>    		tasklet_hi_schedule(&sched_engine->tasklet);
>>> @@ -805,7 +1109,8 @@ static void unpin_guc_id(struct intel_guc *guc, struct intel_context *ce)
>>>    static int __guc_action_register_context(struct intel_guc *guc,
>>>    					 u32 guc_id,
>>> -					 u32 offset)
>>> +					 u32 offset,
>>> +					 bool loop)
>>>    {
>>>    	u32 action[] = {
>>>    		INTEL_GUC_ACTION_REGISTER_CONTEXT,
>>> @@ -813,10 +1118,10 @@ static int __guc_action_register_context(struct intel_guc *guc,
>>>    		offset,
>>>    	};
>>> -	return guc_submission_busy_loop(guc, action, ARRAY_SIZE(action), 0, true);
>>> +	return guc_submission_busy_loop(guc, action, ARRAY_SIZE(action), 0, loop);
>>>    }
>>> -static int register_context(struct intel_context *ce)
>>> +static int register_context(struct intel_context *ce, bool loop)
>>>    {
>>>    	struct intel_guc *guc = ce_to_guc(ce);
>>>    	u32 offset = intel_guc_ggtt_offset(guc, guc->lrc_desc_pool) +
>>> @@ -824,11 +1129,12 @@ static int register_context(struct intel_context *ce)
>>>    	trace_intel_context_register(ce);
>>> -	return __guc_action_register_context(guc, ce->guc_id, offset);
>>> +	return __guc_action_register_context(guc, ce->guc_id, offset, loop);
>>>    }
>>>    static int __guc_action_deregister_context(struct intel_guc *guc,
>>> -					   u32 guc_id)
>>> +					   u32 guc_id,
>>> +					   bool loop)
>>>    {
>>>    	u32 action[] = {
>>>    		INTEL_GUC_ACTION_DEREGISTER_CONTEXT,
>>> @@ -836,16 +1142,16 @@ static int __guc_action_deregister_context(struct intel_guc *guc,
>>>    	};
>>>    	return guc_submission_busy_loop(guc, action, ARRAY_SIZE(action),
>>> -					G2H_LEN_DW_DEREGISTER_CONTEXT, true);
>>> +					G2H_LEN_DW_DEREGISTER_CONTEXT, loop);
>>>    }
>>> -static int deregister_context(struct intel_context *ce, u32 guc_id)
>>> +static int deregister_context(struct intel_context *ce, u32 guc_id, bool loop)
>>>    {
>>>    	struct intel_guc *guc = ce_to_guc(ce);
>>>    	trace_intel_context_deregister(ce);
>>> -	return __guc_action_deregister_context(guc, guc_id);
>>> +	return __guc_action_deregister_context(guc, guc_id, loop);
>>>    }
>>>    static intel_engine_mask_t adjust_engine_mask(u8 class, intel_engine_mask_t mask)
>>> @@ -874,7 +1180,7 @@ static void guc_context_policy_init(struct intel_engine_cs *engine,
>>>    	desc->preemption_timeout = CONTEXT_POLICY_DEFAULT_PREEMPTION_TIME_US;
>>>    }
>>> -static int guc_lrc_desc_pin(struct intel_context *ce)
>>> +static int guc_lrc_desc_pin(struct intel_context *ce, bool loop)
>>>    {
>>>    	struct intel_runtime_pm *runtime_pm =
>>>    		&ce->engine->gt->i915->runtime_pm;
>>> @@ -920,18 +1226,44 @@ static int guc_lrc_desc_pin(struct intel_context *ce)
>>>    	 */
>>>    	if (context_registered) {
>>>    		trace_intel_context_steal_guc_id(ce);
>>> -		set_context_wait_for_deregister_to_register(ce);
>>> -		intel_context_get(ce);
>>> +		if (!loop) {
>>> +			set_context_wait_for_deregister_to_register(ce);
>>> +			intel_context_get(ce);
>>> +		} else {
>>> +			bool disabled;
>>> +			unsigned long flags;
>>> +
>>> +			/* Seal race with Reset */
>>> +			spin_lock_irqsave(&ce->guc_state.lock, flags);
>>> +			disabled = submission_disabled(guc);
>>> +			if (likely(!disabled)) {
>>> +				set_context_wait_for_deregister_to_register(ce);
>>> +				intel_context_get(ce);
>>> +			}
>>> +			spin_unlock_irqrestore(&ce->guc_state.lock, flags);
>>> +			if (unlikely(disabled)) {
>>> +				reset_lrc_desc(guc, desc_idx);
>>> +				return 0;	/* Will get registered later */
>>> +			}
>>> +		}
>>>    		/*
>>>    		 * If stealing the guc_id, this ce has the same guc_id as the
>>>    		 * context whos guc_id was stole.
>>>    		 */
>>>    		with_intel_runtime_pm(runtime_pm, wakeref)
>>> -			ret = deregister_context(ce, ce->guc_id);
>>> +			ret = deregister_context(ce, ce->guc_id, loop);
>>> +		if (unlikely(ret == -EBUSY)) {
>>> +			clr_context_wait_for_deregister_to_register(ce);
>>> +			intel_context_put(ce);
>>> +		}
>>>    	} else {
>>>    		with_intel_runtime_pm(runtime_pm, wakeref)
>>> -			ret = register_context(ce);
>>> +			ret = register_context(ce, loop);
>>> +		if (unlikely(ret == -EBUSY))
>>> +			reset_lrc_desc(guc, desc_idx);
>>> +		else if (unlikely(ret == -ENODEV))
>>> +			ret = 0;	/* Will get registered later */
>>>    	}
>>>    	return ret;
>>> @@ -994,7 +1326,6 @@ static void __guc_context_sched_disable(struct intel_guc *guc,
>>>    	GEM_BUG_ON(guc_id == GUC_INVALID_LRC_ID);
>>>    	trace_intel_context_sched_disable(ce);
>>> -	intel_context_get(ce);
>>>    	guc_submission_busy_loop(guc, action, ARRAY_SIZE(action),
>>>    				 G2H_LEN_DW_SCHED_CONTEXT_MODE_SET, true);
>>> @@ -1004,6 +1335,7 @@ static u16 prep_context_pending_disable(struct intel_context *ce)
>>>    {
>>>    	set_context_pending_disable(ce);
>>>    	clr_context_enabled(ce);
>>> +	intel_context_get(ce);
>>>    	return ce->guc_id;
>>>    }
>>> @@ -1016,7 +1348,7 @@ static void guc_context_sched_disable(struct intel_context *ce)
>>>    	u16 guc_id;
>>>    	intel_wakeref_t wakeref;
>>> -	if (context_guc_id_invalid(ce) ||
>>> +	if (submission_disabled(guc) || context_guc_id_invalid(ce) ||
>>>    	    !lrc_desc_registered(guc, ce->guc_id)) {
>>>    		clr_context_enabled(ce);
>>>    		goto unpin;
>>> @@ -1034,6 +1366,7 @@ static void guc_context_sched_disable(struct intel_context *ce)
>>>    	 * request doesn't slip through the 'context_pending_disable' fence.
>>>    	 */
>>>    	if (unlikely(atomic_add_unless(&ce->pin_count, -2, 2))) {
>>> +		spin_unlock_irqrestore(&ce->guc_state.lock, flags);
>>>    		return;
>>>    	}
>>>    	guc_id = prep_context_pending_disable(ce);
>>> @@ -1050,19 +1383,13 @@ static void guc_context_sched_disable(struct intel_context *ce)
>>>    static inline void guc_lrc_desc_unpin(struct intel_context *ce)
>>>    {
>>> -	struct intel_engine_cs *engine = ce->engine;
>>> -	struct intel_guc *guc = &engine->gt->uc.guc;
>>> -	unsigned long flags;
>>> +	struct intel_guc *guc = ce_to_guc(ce);
>>>    	GEM_BUG_ON(!lrc_desc_registered(guc, ce->guc_id));
>>>    	GEM_BUG_ON(ce != __get_context(guc, ce->guc_id));
>>>    	GEM_BUG_ON(context_enabled(ce));
>>> -	spin_lock_irqsave(&ce->guc_state.lock, flags);
>>> -	set_context_destroyed(ce);
>>> -	spin_unlock_irqrestore(&ce->guc_state.lock, flags);
>>> -
>>> -	deregister_context(ce, ce->guc_id);
>>> +	deregister_context(ce, ce->guc_id, true);
>>>    }
>>>    static void __guc_context_destroy(struct intel_context *ce)
>>> @@ -1090,13 +1417,15 @@ static void guc_context_destroy(struct kref *kref)
>>>    	struct intel_guc *guc = &ce->engine->gt->uc.guc;
>>>    	intel_wakeref_t wakeref;
>>>    	unsigned long flags;
>>> +	bool disabled;
>>>    	/*
>>>    	 * If the guc_id is invalid this context has been stolen and we can free
>>>    	 * it immediately. Also can be freed immediately if the context is not
>>>    	 * registered with the GuC.
>>>    	 */
>>> -	if (context_guc_id_invalid(ce) ||
>>> +	if (submission_disabled(guc) ||
>>> +	    context_guc_id_invalid(ce) ||
>>>    	    !lrc_desc_registered(guc, ce->guc_id)) {
>>>    		release_guc_id(guc, ce);
>>>    		__guc_context_destroy(ce);
>>> @@ -1123,6 +1452,18 @@ static void guc_context_destroy(struct kref *kref)
>>>    		list_del_init(&ce->guc_id_link);
>>>    	spin_unlock_irqrestore(&guc->contexts_lock, flags);
>>> +	/* Seal race with Reset */
>>> +	spin_lock_irqsave(&ce->guc_state.lock, flags);
>>> +	disabled = submission_disabled(guc);
>>> +	if (likely(!disabled))
>>> +		set_context_destroyed(ce);
>>> +	spin_unlock_irqrestore(&ce->guc_state.lock, flags);
>>> +	if (unlikely(disabled)) {
>>> +		release_guc_id(guc, ce);
>>> +		__guc_context_destroy(ce);
>>> +		return;
>>> +	}
>>> +
>>>    	/*
>>>    	 * We defer GuC context deregistration until the context is destroyed
>>>    	 * in order to save on CTBs. With this optimization ideally we only need
>>> @@ -1145,6 +1486,33 @@ static int guc_context_alloc(struct intel_context *ce)
>>>    	return lrc_alloc(ce, ce->engine);
>>>    }
>>> +static void add_to_context(struct i915_request *rq)
>>> +{
>>> +	struct intel_context *ce = rq->context;
>>> +
>>> +	spin_lock(&ce->guc_active.lock);
>>> +	list_move_tail(&rq->sched.link, &ce->guc_active.requests);
>>> +	spin_unlock(&ce->guc_active.lock);
>>> +}
>>> +
>>> +static void remove_from_context(struct i915_request *rq)
>>> +{
>>> +	struct intel_context *ce = rq->context;
>>> +
>>> +	spin_lock_irq(&ce->guc_active.lock);
>>> +
>>> +	list_del_init(&rq->sched.link);
>>> +	clear_bit(I915_FENCE_FLAG_PQUEUE, &rq->fence.flags);
>>> +
>>> +	/* Prevent further __await_execution() registering a cb, then flush */
>>> +	set_bit(I915_FENCE_FLAG_ACTIVE, &rq->fence.flags);
>>> +
>>> +	spin_unlock_irq(&ce->guc_active.lock);
>>> +
>>> +	atomic_dec(&ce->guc_id_ref);
>>> +	i915_request_notify_execute_cb_imm(rq);
>>> +}
>>> +
>>>    static const struct intel_context_ops guc_context_ops = {
>>>    	.alloc = guc_context_alloc,
>>> @@ -1183,8 +1551,6 @@ static void guc_signal_context_fence(struct intel_context *ce)
>>>    {
>>>    	unsigned long flags;
>>> -	GEM_BUG_ON(!context_wait_for_deregister_to_register(ce));
>>> -
>>>    	spin_lock_irqsave(&ce->guc_state.lock, flags);
>>>    	clr_context_wait_for_deregister_to_register(ce);
>>>    	__guc_signal_context_fence(ce);
>>> @@ -1193,8 +1559,9 @@ static void guc_signal_context_fence(struct intel_context *ce)
>>>    static bool context_needs_register(struct intel_context *ce, bool new_guc_id)
>>>    {
>>> -	return new_guc_id || test_bit(CONTEXT_LRCA_DIRTY, &ce->flags) ||
>>> -		!lrc_desc_registered(ce_to_guc(ce), ce->guc_id);
>>> +	return (new_guc_id || test_bit(CONTEXT_LRCA_DIRTY, &ce->flags) ||
>>> +		!lrc_desc_registered(ce_to_guc(ce), ce->guc_id)) &&
>>> +		!submission_disabled(ce_to_guc(ce));
>>>    }
>>>    static int guc_request_alloc(struct i915_request *rq)
>>> @@ -1252,8 +1619,12 @@ static int guc_request_alloc(struct i915_request *rq)
>>>    	if (unlikely(ret < 0))
>>>    		return ret;;
>>>    	if (context_needs_register(ce, !!ret)) {
>>> -		ret = guc_lrc_desc_pin(ce);
>>> +		ret = guc_lrc_desc_pin(ce, true);
>>>    		if (unlikely(ret)) {	/* unwind */
>>> +			if (ret == -EIO) {
>>> +				disable_submission(guc);
>>> +				goto out;	/* GPU will be reset */
>>> +			}
>>>    			atomic_dec(&ce->guc_id_ref);
>>>    			unpin_guc_id(guc, ce);
>>>    			return ret;
>>> @@ -1290,20 +1661,6 @@ static int guc_request_alloc(struct i915_request *rq)
>>>    	return 0;
>>>    }
>>> -static struct intel_engine_cs *
>>> -guc_virtual_get_sibling(struct intel_engine_cs *ve, unsigned int sibling)
>>> -{
>>> -	struct intel_engine_cs *engine;
>>> -	intel_engine_mask_t tmp, mask = ve->mask;
>>> -	unsigned int num_siblings = 0;
>>> -
>>> -	for_each_engine_masked(engine, ve->gt, mask, tmp)
>>> -		if (num_siblings++ == sibling)
>>> -			return engine;
>>> -
>>> -	return NULL;
>>> -}
>>> -
>>>    static int guc_virtual_context_pre_pin(struct intel_context *ce,
>>>    				       struct i915_gem_ww_ctx *ww,
>>>    				       void **vaddr)
>>> @@ -1512,7 +1869,7 @@ static inline void guc_kernel_context_pin(struct intel_guc *guc,
>>>    {
>>>    	if (context_guc_id_invalid(ce))
>>>    		pin_guc_id(guc, ce);
>>> -	guc_lrc_desc_pin(ce);
>>> +	guc_lrc_desc_pin(ce, true);
>>>    }
>>>    static inline void guc_init_lrc_mapping(struct intel_guc *guc)
>>> @@ -1578,13 +1935,15 @@ static void guc_default_vfuncs(struct intel_engine_cs *engine)
>>>    	engine->cops = &guc_context_ops;
>>>    	engine->request_alloc = guc_request_alloc;
>>>    	engine->bump_serial = guc_bump_serial;
>>> +	engine->add_active_request = add_to_context;
>>> +	engine->remove_active_request = remove_from_context;
>>>    	engine->sched_engine->schedule = i915_schedule;
>>> -	engine->reset.prepare = guc_reset_prepare;
>>> -	engine->reset.rewind = guc_reset_rewind;
>>> -	engine->reset.cancel = guc_reset_cancel;
>>> -	engine->reset.finish = guc_reset_finish;
>>> +	engine->reset.prepare = guc_reset_nop;
>>> +	engine->reset.rewind = guc_rewind_nop;
>>> +	engine->reset.cancel = guc_reset_nop;
>>> +	engine->reset.finish = guc_reset_nop;
>>>    	engine->emit_flush = gen8_emit_flush_xcs;
>>>    	engine->emit_init_breadcrumb = gen8_emit_init_breadcrumb;
>>> @@ -1757,7 +2116,7 @@ int intel_guc_deregister_done_process_msg(struct intel_guc *guc,
>>>    		 * register this context.
>>>    		 */
>>>    		with_intel_runtime_pm(runtime_pm, wakeref)
>>> -			register_context(ce);
>>> +			register_context(ce, true);
>>>    		guc_signal_context_fence(ce);
>>>    		intel_context_put(ce);
>>>    	} else if (context_destroyed(ce)) {
>>> @@ -1939,6 +2298,10 @@ guc_create_virtual(struct intel_engine_cs **siblings, unsigned int count)
>>>    				 "v%dx%d", ve->base.class, count);
>>>    			ve->base.context_size = sibling->context_size;
>>> +			ve->base.add_active_request =
>>> +				sibling->add_active_request;
>>> +			ve->base.remove_active_request =
>>> +				sibling->remove_active_request;
>>>    			ve->base.emit_bb_start = sibling->emit_bb_start;
>>>    			ve->base.emit_flush = sibling->emit_flush;
>>>    			ve->base.emit_init_breadcrumb =
>>> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_uc.c b/drivers/gpu/drm/i915/gt/uc/intel_uc.c
>>> index 6d8b9233214e..f0b02200aa01 100644
>>> --- a/drivers/gpu/drm/i915/gt/uc/intel_uc.c
>>> +++ b/drivers/gpu/drm/i915/gt/uc/intel_uc.c
>>> @@ -565,12 +565,49 @@ void intel_uc_reset_prepare(struct intel_uc *uc)
>>>    {
>>>    	struct intel_guc *guc = &uc->guc;
>>> -	if (!intel_guc_is_ready(guc))
>>> +
>>> +	/* Nothing to do if GuC isn't supported */
>>> +	if (!intel_uc_supports_guc(uc))
>>>    		return;
>>> +	/* Firmware expected to be running when this function is called */
>>> +	if (!intel_guc_is_ready(guc))
>>> +		goto sanitize;
>>> +
>>> +	if (intel_uc_uses_guc_submission(uc))
>>> +		intel_guc_submission_reset_prepare(guc);
>>> +
>>> +sanitize:
>>>    	__uc_sanitize(uc);
>>>    }
>>> +void intel_uc_reset(struct intel_uc *uc, bool stalled)
>>> +{
>>> +	struct intel_guc *guc = &uc->guc;
>>> +
>>> +	/* Firmware can not be running when this function is called  */
>>> +	if (intel_uc_uses_guc_submission(uc))
>>> +		intel_guc_submission_reset(guc, stalled);
>>> +}
>>> +
>>> +void intel_uc_reset_finish(struct intel_uc *uc)
>>> +{
>>> +	struct intel_guc *guc = &uc->guc;
>>> +
>>> +	/* Firmware expected to be running when this function is called */
>>> +	if (intel_guc_is_fw_running(guc) && intel_uc_uses_guc_submission(uc))
>>> +		intel_guc_submission_reset_finish(guc);
>>> +}
>>> +
>>> +void intel_uc_cancel_requests(struct intel_uc *uc)
>>> +{
>>> +	struct intel_guc *guc = &uc->guc;
>>> +
>>> +	/* Firmware can not be running when this function is called  */
>>> +	if (intel_uc_uses_guc_submission(uc))
>>> +		intel_guc_submission_cancel_requests(guc);
>>> +}
>>> +
>>>    void intel_uc_runtime_suspend(struct intel_uc *uc)
>>>    {
>>>    	struct intel_guc *guc = &uc->guc;
>>> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_uc.h b/drivers/gpu/drm/i915/gt/uc/intel_uc.h
>>> index c4cef885e984..eaa3202192ac 100644
>>> --- a/drivers/gpu/drm/i915/gt/uc/intel_uc.h
>>> +++ b/drivers/gpu/drm/i915/gt/uc/intel_uc.h
>>> @@ -37,6 +37,9 @@ void intel_uc_driver_late_release(struct intel_uc *uc);
>>>    void intel_uc_driver_remove(struct intel_uc *uc);
>>>    void intel_uc_init_mmio(struct intel_uc *uc);
>>>    void intel_uc_reset_prepare(struct intel_uc *uc);
>>> +void intel_uc_reset(struct intel_uc *uc, bool stalled);
>>> +void intel_uc_reset_finish(struct intel_uc *uc);
>>> +void intel_uc_cancel_requests(struct intel_uc *uc);
>>>    void intel_uc_suspend(struct intel_uc *uc);
>>>    void intel_uc_runtime_suspend(struct intel_uc *uc);
>>>    int intel_uc_resume(struct intel_uc *uc);
>>> diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
>>> index dec5a35c9aa2..192784875a1d 100644
>>> --- a/drivers/gpu/drm/i915/i915_request.c
>>> +++ b/drivers/gpu/drm/i915/i915_request.c
>>> @@ -194,7 +194,7 @@ static bool irq_work_imm(struct irq_work *wrk)
>>>    	return false;
>>>    }
>>> -static void __notify_execute_cb_imm(struct i915_request *rq)
>>> +void i915_request_notify_execute_cb_imm(struct i915_request *rq)
>>>    {
>>>    	__notify_execute_cb(rq, irq_work_imm);
>>>    }
>>> @@ -268,37 +268,6 @@ i915_request_active_engine(struct i915_request *rq,
>>>    	return ret;
>>>    }
>>> -
>>> -static void remove_from_engine(struct i915_request *rq)
>>> -{
>>> -	struct intel_engine_cs *engine, *locked;
>>> -
>>> -	/*
>>> -	 * Virtual engines complicate acquiring the engine timeline lock,
>>> -	 * as their rq->engine pointer is not stable until under that
>>> -	 * engine lock. The simple ploy we use is to take the lock then
>>> -	 * check that the rq still belongs to the newly locked engine.
>>> -	 */
>>> -	locked = READ_ONCE(rq->engine);
>>> -	spin_lock_irq(&locked->sched_engine->lock);
>>> -	while (unlikely(locked != (engine = READ_ONCE(rq->engine)))) {
>>> -		spin_unlock(&locked->sched_engine->lock);
>>> -		spin_lock(&engine->sched_engine->lock);
>>> -		locked = engine;
>>> -	}
>>> -	list_del_init(&rq->sched.link);
>>> -
>>> -	clear_bit(I915_FENCE_FLAG_PQUEUE, &rq->fence.flags);
>>> -	clear_bit(I915_FENCE_FLAG_HOLD, &rq->fence.flags);
>>> -
>>> -	/* Prevent further __await_execution() registering a cb, then flush */
>>> -	set_bit(I915_FENCE_FLAG_ACTIVE, &rq->fence.flags);
>>> -
>>> -	spin_unlock_irq(&locked->sched_engine->lock);
>>> -
>>> -	__notify_execute_cb_imm(rq);
>>> -}
>>> -
>>>    static void __rq_init_watchdog(struct i915_request *rq)
>>>    {
>>>    	rq->watchdog.timer.function = NULL;
>>> @@ -395,9 +364,7 @@ bool i915_request_retire(struct i915_request *rq)
>>>    	 * after removing the breadcrumb and signaling it, so that we do not
>>>    	 * inadvertently attach the breadcrumb to a completed request.
>>>    	 */
>>> -	if (!list_empty(&rq->sched.link))
>>> -		remove_from_engine(rq);
>>> -	atomic_dec(&rq->context->guc_id_ref);
>>> +	rq->engine->remove_active_request(rq);
>>>    	GEM_BUG_ON(!llist_empty(&rq->execute_cb));
>>>    	__list_del_entry(&rq->link); /* poison neither prev/next (RCU walks) */
>>> @@ -539,7 +506,7 @@ __await_execution(struct i915_request *rq,
>>>    	if (llist_add(&cb->work.node.llist, &signal->execute_cb)) {
>>>    		if (i915_request_is_active(signal) ||
>>>    		    __request_in_flight(signal))
>>> -			__notify_execute_cb_imm(signal);
>>> +			i915_request_notify_execute_cb_imm(signal);
>>>    	}
>>>    	return 0;
>>> @@ -676,7 +643,7 @@ bool __i915_request_submit(struct i915_request *request)
>>>    	result = true;
>>>    	GEM_BUG_ON(test_bit(I915_FENCE_FLAG_ACTIVE, &request->fence.flags));
>>> -	list_move_tail(&request->sched.link, &engine->sched_engine->requests);
>>> +	engine->add_active_request(request);
>>>    active:
>>>    	clear_bit(I915_FENCE_FLAG_PQUEUE, &request->fence.flags);
>>>    	set_bit(I915_FENCE_FLAG_ACTIVE, &request->fence.flags);
>>> diff --git a/drivers/gpu/drm/i915/i915_request.h b/drivers/gpu/drm/i915/i915_request.h
>>> index f870cd75a001..bcc6340c505e 100644
>>> --- a/drivers/gpu/drm/i915/i915_request.h
>>> +++ b/drivers/gpu/drm/i915/i915_request.h
>>> @@ -649,4 +649,6 @@ bool
>>>    i915_request_active_engine(struct i915_request *rq,
>>>    			   struct intel_engine_cs **active);
>>> +void i915_request_notify_execute_cb_imm(struct i915_request *rq);
>>> +
>>>    #endif /* I915_REQUEST_H */
>>>

Matthew Brost July 27, 2021, 6:30 p.m. UTC | #6

On Tue, Jul 27, 2021 at 09:56:06AM +0100, Tvrtko Ursulin wrote:
> 
> On 26/07/2021 23:48, Matthew Brost wrote:
> > On Thu, Jul 15, 2021 at 10:36:51AM +0100, Tvrtko Ursulin wrote:
> > > 
> > > On 24/06/2021 08:05, Matthew Brost wrote:
> > > > Reset implementation for new GuC interface. This is the legacy reset
> > > > implementation which is called when the i915 owns the engine hang check.
> > > > Future patches will offload the engine hang check to GuC but we will
> > > > continue to maintain this legacy path as a fallback and this code path
> > > > is also required if the GuC dies.
> > > > 
> > > > With the new GuC interface it is not possible to reset individual
> > > > engines - it is only possible to reset the GPU entirely. This patch
> > > > forces an entire chip reset if any engine hangs.
> > > 
> > > No updates after my review comments on 6th of May.
> > > 
> > > At least:
> > > 
> > > 1. wmb documentation
> > > 
> > 
> > Yea, missed this. Checkpatch yelled at me too. Will be fixed in next
> > rev.
> > 
> > > 2. Spin lock cycling I either didn't understand or didn't buy the
> > > explanation. I don't remember seeing that pattern elsewhere in the driver -
> > > cycle a spinlock to make sure what was updated inside it is visible you
> > > said?
> > > 
> > 
> > I did respond - not really my fault if you don't understand a fairly
> > simple concept but I'll explain again.
> > 
> > Change a variable
> > Cycle a lock
> > At this point we know anyone that acquires above lock the variable
> > change is visible.
> > 
> > I can't be the first person in the Linux kernel to do this nor in the
> > i915.
> 
> Don't know, did not do an exhaustive search. I can understand it being used
> to make sure any lock taking sections would exit, if they happened to be
> running simultaneously to the lock cycling code, but you seem to be
> describing it being used as a memory barrier.
> 
> So either a code comment or just use a memory barrier is my ask. There is a
> requirement to comment memory barriers anyway so if this is effectively one
> of them it's pretty clear cut.
> 

This more than a memory barrier, not just ensuring that variable change
is visible but any actions before the change was visible are complete.

> > This basically allows to seal all the reset races without a BKL.
> > 
> > Also I told you I explain in this a doc patch that will get reposted
> > after GuC submission lands:
> > https://patchwork.freedesktop.org/patch/432408/?series=89844&rev=1
> > 
> > > 3. Dropping the lock protecting the list in the middle of
> > > list_for_each_entry_safe and just continuing to iterate like nothing
> > > happened. (__unwind_incomplete_requests) Again, perhaps I did not understand
> > > your explanation properly but you did appear to write:
> > > 
> > 
> > To be honest looking at the code now we likely don't need to drop the
> > look but regardless I don't think we should change this for the
> > following reasons.
> 
> Then don't?
>

Ok, let me write this down and do this in an immediate follow up after
some thorough testing.

Matt

> > 1. I assure you this is safe and works. I can add a better comment
> > explaining this though.
> 
> Yes please for a comment. Assurances are all good until a new bug is found.
> 
> > 2. This is thoroughly tested and resets are the hardest thing to get
> > stable and working.
> 
> Well new bugs are found even after statements of things being well tested so
> I'd err on the side of caution. And I don't mean your code here but as a
> general principle.
> 
> > 3. This code is literally going to get deleted when we move to the DRM
> > scheduler as all the tracking / unwinding / resubmission will be in the
> > DRM scheduler core.
> 
> Yeah, but if that cannot be guaranteed to happen in the same kernel release
> then lets not put dodgy code in.
> 
> > 4. A 2 second search of the driver found that we do the same thing in
> > intel_gt_retire_requests_timeout so this isn't unprecedented.
> 
> The code there is bit different. It uses list_safe_reset_next after
> re-acquiring the lock and only then unlinks the current element from the
> list.
> 
> It all boils down to whether something can modify the list in parallel in
> your case. If it can't, just don't take the lock but instead put a comment
> saying why the lock does not need to be taken would be my suggestion. That
> way you avoid having to explain why the iteration is not broken.
> 
> Regards,
> 
> Tvrtko
> 
> > 
> > Matt
> > 
> > > """
> > > We only need the active lock for ce->guc_active.requests list. It is
> > > indeed safe to drop the lock.
> > > """
> > > 
> > > +	spin_lock(&ce->guc_active.lock);
> > > +	list_for_each_entry_safe(rq, rn,
> > > +				 &ce->guc_active.requests,
> > > +				 sched.link) {
> > > +		if (i915_request_completed(rq))
> > > +			continue;
> > > +
> > > +		list_del_init(&rq->sched.link);
> > > +		spin_unlock(&ce->guc_active.lock);
> > > ...
> > > +		spin_lock(&ce->guc_active.lock);
> > > +	}
> > > 
> > > Safe iterator guards against list_del but dropping the lock means the state
> > > of the overall list can change so next pointer may or may not be valid,
> > > requests may be missed, I don't know. Needs a comment explaining why it is
> > > safe.
> > > 
> > > Regards,
> > > 
> > > Tvrtko
> > > 
> > > > 
> > > > Cc: John Harrison <[e-mail]>
> > > > Signed-off-by: Matthew Brost <[e-mail]>
> > > > ---
> > > >    drivers/gpu/drm/i915/gt/intel_context.c       |   3 +
> > > >    drivers/gpu/drm/i915/gt/intel_context_types.h |   7 +
> > > >    drivers/gpu/drm/i915/gt/intel_engine_types.h  |   6 +
> > > >    .../drm/i915/gt/intel_execlists_submission.c  |  40 ++
> > > >    drivers/gpu/drm/i915/gt/intel_gt_pm.c         |   6 +-
> > > >    drivers/gpu/drm/i915/gt/intel_reset.c         |  18 +-
> > > >    .../gpu/drm/i915/gt/intel_ring_submission.c   |  22 +
> > > >    drivers/gpu/drm/i915/gt/mock_engine.c         |  31 +
> > > >    drivers/gpu/drm/i915/gt/uc/intel_guc.c        |  13 -
> > > >    drivers/gpu/drm/i915/gt/uc/intel_guc.h        |   8 +-
> > > >    .../gpu/drm/i915/gt/uc/intel_guc_submission.c | 581 ++++++++++++++----
> > > >    drivers/gpu/drm/i915/gt/uc/intel_uc.c         |  39 +-
> > > >    drivers/gpu/drm/i915/gt/uc/intel_uc.h         |   3 +
> > > >    drivers/gpu/drm/i915/i915_request.c           |  41 +-
> > > >    drivers/gpu/drm/i915/i915_request.h           |   2 +
> > > >    15 files changed, 649 insertions(+), 171 deletions(-)
> > > > 
> > > > diff --git a/drivers/gpu/drm/i915/gt/intel_context.c b/drivers/gpu/drm/i915/gt/intel_context.c
> > > > index b24a1b7a3f88..2f01437056a8 100644
> > > > --- a/drivers/gpu/drm/i915/gt/intel_context.c
> > > > +++ b/drivers/gpu/drm/i915/gt/intel_context.c
> > > > @@ -392,6 +392,9 @@ intel_context_init(struct intel_context *ce, struct intel_engine_cs *engine)
> > > >    	spin_lock_init(&ce->guc_state.lock);
> > > >    	INIT_LIST_HEAD(&ce->guc_state.fences);
> > > > +	spin_lock_init(&ce->guc_active.lock);
> > > > +	INIT_LIST_HEAD(&ce->guc_active.requests);
> > > > +
> > > >    	ce->guc_id = GUC_INVALID_LRC_ID;
> > > >    	INIT_LIST_HEAD(&ce->guc_id_link);
> > > > diff --git a/drivers/gpu/drm/i915/gt/intel_context_types.h b/drivers/gpu/drm/i915/gt/intel_context_types.h
> > > > index 6945963a31ba..b63c8cf7823b 100644
> > > > --- a/drivers/gpu/drm/i915/gt/intel_context_types.h
> > > > +++ b/drivers/gpu/drm/i915/gt/intel_context_types.h
> > > > @@ -165,6 +165,13 @@ struct intel_context {
> > > >    		struct list_head fences;
> > > >    	} guc_state;
> > > > +	struct {
> > > > +		/** lock: protects everything in guc_active */
> > > > +		spinlock_t lock;
> > > > +		/** requests: active requests on this context */
> > > > +		struct list_head requests;
> > > > +	} guc_active;
> > > > +
> > > >    	/* GuC scheduling state that does not require a lock. */
> > > >    	atomic_t guc_sched_state_no_lock;
> > > > diff --git a/drivers/gpu/drm/i915/gt/intel_engine_types.h b/drivers/gpu/drm/i915/gt/intel_engine_types.h
> > > > index e7cb6a06db9d..f9d264c008e8 100644
> > > > --- a/drivers/gpu/drm/i915/gt/intel_engine_types.h
> > > > +++ b/drivers/gpu/drm/i915/gt/intel_engine_types.h
> > > > @@ -426,6 +426,12 @@ struct intel_engine_cs {
> > > >    	void		(*release)(struct intel_engine_cs *engine);
> > > > +	/*
> > > > +	 * Add / remove request from engine active tracking
> > > > +	 */
> > > > +	void		(*add_active_request)(struct i915_request *rq);
> > > > +	void		(*remove_active_request)(struct i915_request *rq);
> > > > +
> > > >    	struct intel_engine_execlists execlists;
> > > >    	/*
> > > > diff --git a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
> > > > index c10ea6080752..c301a2d088b1 100644
> > > > --- a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
> > > > +++ b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
> > > > @@ -3118,6 +3118,42 @@ static void execlists_park(struct intel_engine_cs *engine)
> > > >    	cancel_timer(&engine->execlists.preempt);
> > > >    }
> > > > +static void add_to_engine(struct i915_request *rq)
> > > > +{
> > > > +	lockdep_assert_held(&rq->engine->sched_engine->lock);
> > > > +	list_move_tail(&rq->sched.link, &rq->engine->sched_engine->requests);
> > > > +}
> > > > +
> > > > +static void remove_from_engine(struct i915_request *rq)
> > > > +{
> > > > +	struct intel_engine_cs *engine, *locked;
> > > > +
> > > > +	/*
> > > > +	 * Virtual engines complicate acquiring the engine timeline lock,
> > > > +	 * as their rq->engine pointer is not stable until under that
> > > > +	 * engine lock. The simple ploy we use is to take the lock then
> > > > +	 * check that the rq still belongs to the newly locked engine.
> > > > +	 */
> > > > +	locked = READ_ONCE(rq->engine);
> > > > +	spin_lock_irq(&locked->sched_engine->lock);
> > > > +	while (unlikely(locked != (engine = READ_ONCE(rq->engine)))) {
> > > > +		spin_unlock(&locked->sched_engine->lock);
> > > > +		spin_lock(&engine->sched_engine->lock);
> > > > +		locked = engine;
> > > > +	}
> > > > +	list_del_init(&rq->sched.link);
> > > > +
> > > > +	clear_bit(I915_FENCE_FLAG_PQUEUE, &rq->fence.flags);
> > > > +	clear_bit(I915_FENCE_FLAG_HOLD, &rq->fence.flags);
> > > > +
> > > > +	/* Prevent further __await_execution() registering a cb, then flush */
> > > > +	set_bit(I915_FENCE_FLAG_ACTIVE, &rq->fence.flags);
> > > > +
> > > > +	spin_unlock_irq(&locked->sched_engine->lock);
> > > > +
> > > > +	i915_request_notify_execute_cb_imm(rq);
> > > > +}
> > > > +
> > > >    static bool can_preempt(struct intel_engine_cs *engine)
> > > >    {
> > > >    	if (GRAPHICS_VER(engine->i915) > 8)
> > > > @@ -3218,6 +3254,8 @@ logical_ring_default_vfuncs(struct intel_engine_cs *engine)
> > > >    	engine->cops = &execlists_context_ops;
> > > >    	engine->request_alloc = execlists_request_alloc;
> > > >    	engine->bump_serial = execlist_bump_serial;
> > > > +	engine->add_active_request = add_to_engine;
> > > > +	engine->remove_active_request = remove_from_engine;
> > > >    	engine->reset.prepare = execlists_reset_prepare;
> > > >    	engine->reset.rewind = execlists_reset_rewind;
> > > > @@ -3912,6 +3950,8 @@ execlists_create_virtual(struct intel_engine_cs **siblings, unsigned int count)
> > > >    			 "v%dx%d", ve->base.class, count);
> > > >    		ve->base.context_size = sibling->context_size;
> > > > +		ve->base.add_active_request = sibling->add_active_request;
> > > > +		ve->base.remove_active_request = sibling->remove_active_request;
> > > >    		ve->base.emit_bb_start = sibling->emit_bb_start;
> > > >    		ve->base.emit_flush = sibling->emit_flush;
> > > >    		ve->base.emit_init_breadcrumb = sibling->emit_init_breadcrumb;
> > > > diff --git a/drivers/gpu/drm/i915/gt/intel_gt_pm.c b/drivers/gpu/drm/i915/gt/intel_gt_pm.c
> > > > index aef3084e8b16..463a6ae605a0 100644
> > > > --- a/drivers/gpu/drm/i915/gt/intel_gt_pm.c
> > > > +++ b/drivers/gpu/drm/i915/gt/intel_gt_pm.c
> > > > @@ -174,8 +174,6 @@ static void gt_sanitize(struct intel_gt *gt, bool force)
> > > >    	if (intel_gt_is_wedged(gt))
> > > >    		intel_gt_unset_wedged(gt);
> > > > -	intel_uc_sanitize(&gt->uc);
> > > > -
> > > >    	for_each_engine(engine, gt, id)
> > > >    		if (engine->reset.prepare)
> > > >    			engine->reset.prepare(engine);
> > > > @@ -191,6 +189,8 @@ static void gt_sanitize(struct intel_gt *gt, bool force)
> > > >    			__intel_engine_reset(engine, false);
> > > >    	}
> > > > +	intel_uc_reset(&gt->uc, false);
> > > > +
> > > >    	for_each_engine(engine, gt, id)
> > > >    		if (engine->reset.finish)
> > > >    			engine->reset.finish(engine);
> > > > @@ -243,6 +243,8 @@ int intel_gt_resume(struct intel_gt *gt)
> > > >    		goto err_wedged;
> > > >    	}
> > > > +	intel_uc_reset_finish(&gt->uc);
> > > > +
> > > >    	intel_rps_enable(&gt->rps);
> > > >    	intel_llc_enable(&gt->llc);
> > > > diff --git a/drivers/gpu/drm/i915/gt/intel_reset.c b/drivers/gpu/drm/i915/gt/intel_reset.c
> > > > index 72251638d4ea..2987282dff6d 100644
> > > > --- a/drivers/gpu/drm/i915/gt/intel_reset.c
> > > > +++ b/drivers/gpu/drm/i915/gt/intel_reset.c
> > > > @@ -826,6 +826,8 @@ static int gt_reset(struct intel_gt *gt, intel_engine_mask_t stalled_mask)
> > > >    		__intel_engine_reset(engine, stalled_mask & engine->mask);
> > > >    	local_bh_enable();
> > > > +	intel_uc_reset(&gt->uc, true);
> > > > +
> > > >    	intel_ggtt_restore_fences(gt->ggtt);
> > > >    	return err;
> > > > @@ -850,6 +852,8 @@ static void reset_finish(struct intel_gt *gt, intel_engine_mask_t awake)
> > > >    		if (awake & engine->mask)
> > > >    			intel_engine_pm_put(engine);
> > > >    	}
> > > > +
> > > > +	intel_uc_reset_finish(&gt->uc);
> > > >    }
> > > >    static void nop_submit_request(struct i915_request *request)
> > > > @@ -903,6 +907,7 @@ static void __intel_gt_set_wedged(struct intel_gt *gt)
> > > >    	for_each_engine(engine, gt, id)
> > > >    		if (engine->reset.cancel)
> > > >    			engine->reset.cancel(engine);
> > > > +	intel_uc_cancel_requests(&gt->uc);
> > > >    	local_bh_enable();
> > > >    	reset_finish(gt, awake);
> > > > @@ -1191,6 +1196,9 @@ int __intel_engine_reset_bh(struct intel_engine_cs *engine, const char *msg)
> > > >    	ENGINE_TRACE(engine, "flags=%lx\n", gt->reset.flags);
> > > >    	GEM_BUG_ON(!test_bit(I915_RESET_ENGINE + engine->id, &gt->reset.flags));
> > > > +	if (intel_engine_uses_guc(engine))
> > > > +		return -ENODEV;
> > > > +
> > > >    	if (!intel_engine_pm_get_if_awake(engine))
> > > >    		return 0;
> > > > @@ -1201,13 +1209,10 @@ int __intel_engine_reset_bh(struct intel_engine_cs *engine, const char *msg)
> > > >    			   "Resetting %s for %s\n", engine->name, msg);
> > > >    	atomic_inc(&engine->i915->gpu_error.reset_engine_count[engine->uabi_class]);
> > > > -	if (intel_engine_uses_guc(engine))
> > > > -		ret = intel_guc_reset_engine(&engine->gt->uc.guc, engine);
> > > > -	else
> > > > -		ret = intel_gt_reset_engine(engine);
> > > > +	ret = intel_gt_reset_engine(engine);
> > > >    	if (ret) {
> > > >    		/* If we fail here, we expect to fallback to a global reset */
> > > > -		ENGINE_TRACE(engine, "Failed to reset, err: %d\n", ret);
> > > > +		ENGINE_TRACE(engine, "Failed to reset %s, err: %d\n", engine->name, ret);
> > > >    		goto out;
> > > >    	}
> > > > @@ -1341,7 +1346,8 @@ void intel_gt_handle_error(struct intel_gt *gt,
> > > >    	 * Try engine reset when available. We fall back to full reset if
> > > >    	 * single reset fails.
> > > >    	 */
> > > > -	if (intel_has_reset_engine(gt) && !intel_gt_is_wedged(gt)) {
> > > > +	if (!intel_uc_uses_guc_submission(&gt->uc) &&
> > > > +	    intel_has_reset_engine(gt) && !intel_gt_is_wedged(gt)) {
> > > >    		local_bh_disable();
> > > >    		for_each_engine_masked(engine, gt, engine_mask, tmp) {
> > > >    			BUILD_BUG_ON(I915_RESET_MODESET >= I915_RESET_ENGINE);
> > > > diff --git a/drivers/gpu/drm/i915/gt/intel_ring_submission.c b/drivers/gpu/drm/i915/gt/intel_ring_submission.c
> > > > index e1506b280df1..99dcdc8fba12 100644
> > > > --- a/drivers/gpu/drm/i915/gt/intel_ring_submission.c
> > > > +++ b/drivers/gpu/drm/i915/gt/intel_ring_submission.c
> > > > @@ -1049,6 +1049,25 @@ static void ring_bump_serial(struct intel_engine_cs *engine)
> > > >    	engine->serial++;
> > > >    }
> > > > +static void add_to_engine(struct i915_request *rq)
> > > > +{
> > > > +	lockdep_assert_held(&rq->engine->sched_engine->lock);
> > > > +	list_move_tail(&rq->sched.link, &rq->engine->sched_engine->requests);
> > > > +}
> > > > +
> > > > +static void remove_from_engine(struct i915_request *rq)
> > > > +{
> > > > +	spin_lock_irq(&rq->engine->sched_engine->lock);
> > > > +	list_del_init(&rq->sched.link);
> > > > +
> > > > +	/* Prevent further __await_execution() registering a cb, then flush */
> > > > +	set_bit(I915_FENCE_FLAG_ACTIVE, &rq->fence.flags);
> > > > +
> > > > +	spin_unlock_irq(&rq->engine->sched_engine->lock);
> > > > +
> > > > +	i915_request_notify_execute_cb_imm(rq);
> > > > +}
> > > > +
> > > >    static void setup_common(struct intel_engine_cs *engine)
> > > >    {
> > > >    	struct drm_i915_private *i915 = engine->i915;
> > > > @@ -1066,6 +1085,9 @@ static void setup_common(struct intel_engine_cs *engine)
> > > >    	engine->reset.cancel = reset_cancel;
> > > >    	engine->reset.finish = reset_finish;
> > > > +	engine->add_active_request = add_to_engine;
> > > > +	engine->remove_active_request = remove_from_engine;
> > > > +
> > > >    	engine->cops = &ring_context_ops;
> > > >    	engine->request_alloc = ring_request_alloc;
> > > >    	engine->bump_serial = ring_bump_serial;
> > > > diff --git a/drivers/gpu/drm/i915/gt/mock_engine.c b/drivers/gpu/drm/i915/gt/mock_engine.c
> > > > index fc5a65ab1937..c12ff3a75ce6 100644
> > > > --- a/drivers/gpu/drm/i915/gt/mock_engine.c
> > > > +++ b/drivers/gpu/drm/i915/gt/mock_engine.c
> > > > @@ -235,6 +235,35 @@ static void mock_submit_request(struct i915_request *request)
> > > >    	spin_unlock_irqrestore(&engine->hw_lock, flags);
> > > >    }
> > > > +static void mock_add_to_engine(struct i915_request *rq)
> > > > +{
> > > > +	lockdep_assert_held(&rq->engine->sched_engine->lock);
> > > > +	list_move_tail(&rq->sched.link, &rq->engine->sched_engine->requests);
> > > > +}
> > > > +
> > > > +static void mock_remove_from_engine(struct i915_request *rq)
> > > > +{
> > > > +	struct intel_engine_cs *engine, *locked;
> > > > +
> > > > +	/*
> > > > +	 * Virtual engines complicate acquiring the engine timeline lock,
> > > > +	 * as their rq->engine pointer is not stable until under that
> > > > +	 * engine lock. The simple ploy we use is to take the lock then
> > > > +	 * check that the rq still belongs to the newly locked engine.
> > > > +	 */
> > > > +
> > > > +	locked = READ_ONCE(rq->engine);
> > > > +	spin_lock_irq(&locked->sched_engine->lock);
> > > > +	while (unlikely(locked != (engine = READ_ONCE(rq->engine)))) {
> > > > +		spin_unlock(&locked->sched_engine->lock);
> > > > +		spin_lock(&engine->sched_engine->lock);
> > > > +		locked = engine;
> > > > +	}
> > > > +	list_del_init(&rq->sched.link);
> > > > +	spin_unlock_irq(&locked->sched_engine->lock);
> > > > +}
> > > > +
> > > > +
> > > >    static void mock_reset_prepare(struct intel_engine_cs *engine)
> > > >    {
> > > >    }
> > > > @@ -327,6 +356,8 @@ struct intel_engine_cs *mock_engine(struct drm_i915_private *i915,
> > > >    	engine->base.emit_flush = mock_emit_flush;
> > > >    	engine->base.emit_fini_breadcrumb = mock_emit_breadcrumb;
> > > >    	engine->base.submit_request = mock_submit_request;
> > > > +	engine->base.add_active_request = mock_add_to_engine;
> > > > +	engine->base.remove_active_request = mock_remove_from_engine;
> > > >    	engine->base.reset.prepare = mock_reset_prepare;
> > > >    	engine->base.reset.rewind = mock_reset_rewind;
> > > > diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc.c b/drivers/gpu/drm/i915/gt/uc/intel_guc.c
> > > > index 6661dcb02239..9b09395b998f 100644
> > > > --- a/drivers/gpu/drm/i915/gt/uc/intel_guc.c
> > > > +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc.c
> > > > @@ -572,19 +572,6 @@ int intel_guc_suspend(struct intel_guc *guc)
> > > >    	return 0;
> > > >    }
> > > > -/**
> > > > - * intel_guc_reset_engine() - ask GuC to reset an engine
> > > > - * @guc:	intel_guc structure
> > > > - * @engine:	engine to be reset
> > > > - */
> > > > -int intel_guc_reset_engine(struct intel_guc *guc,
> > > > -			   struct intel_engine_cs *engine)
> > > > -{
> > > > -	/* XXX: to be implemented with submission interface rework */
> > > > -
> > > > -	return -ENODEV;
> > > > -}
> > > > -
> > > >    /**
> > > >     * intel_guc_resume() - notify GuC resuming from suspend state
> > > >     * @guc:	the guc
> > > > diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc.h b/drivers/gpu/drm/i915/gt/uc/intel_guc.h
> > > > index 22eb1e9cca41..40c9868762d7 100644
> > > > --- a/drivers/gpu/drm/i915/gt/uc/intel_guc.h
> > > > +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc.h
> > > > @@ -242,14 +242,16 @@ static inline void intel_guc_disable_msg(struct intel_guc *guc, u32 mask)
> > > >    int intel_guc_wait_for_idle(struct intel_guc *guc, long timeout);
> > > > -int intel_guc_reset_engine(struct intel_guc *guc,
> > > > -			   struct intel_engine_cs *engine);
> > > > -
> > > >    int intel_guc_deregister_done_process_msg(struct intel_guc *guc,
> > > >    					  const u32 *msg, u32 len);
> > > >    int intel_guc_sched_done_process_msg(struct intel_guc *guc,
> > > >    				     const u32 *msg, u32 len);
> > > > +void intel_guc_submission_reset_prepare(struct intel_guc *guc);
> > > > +void intel_guc_submission_reset(struct intel_guc *guc, bool stalled);
> > > > +void intel_guc_submission_reset_finish(struct intel_guc *guc);
> > > > +void intel_guc_submission_cancel_requests(struct intel_guc *guc);
> > > > +
> > > >    void intel_guc_load_status(struct intel_guc *guc, struct drm_printer *p);
> > > >    #endif
> > > > diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> > > > index 83058df5ba01..b8c894ad8caf 100644
> > > > --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> > > > +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> > > > @@ -141,7 +141,7 @@ context_wait_for_deregister_to_register(struct intel_context *ce)
> > > >    static inline void
> > > >    set_context_wait_for_deregister_to_register(struct intel_context *ce)
> > > >    {
> > > > -	/* Only should be called from guc_lrc_desc_pin() */
> > > > +	/* Only should be called from guc_lrc_desc_pin() without lock */
> > > >    	ce->guc_state.sched_state |=
> > > >    		SCHED_STATE_WAIT_FOR_DEREGISTER_TO_REGISTER;
> > > >    }
> > > > @@ -241,15 +241,31 @@ static int guc_lrc_desc_pool_create(struct intel_guc *guc)
> > > >    static void guc_lrc_desc_pool_destroy(struct intel_guc *guc)
> > > >    {
> > > > +	guc->lrc_desc_pool_vaddr = NULL;
> > > >    	i915_vma_unpin_and_release(&guc->lrc_desc_pool, I915_VMA_RELEASE_MAP);
> > > >    }
> > > > +static inline bool guc_submission_initialized(struct intel_guc *guc)
> > > > +{
> > > > +	return guc->lrc_desc_pool_vaddr != NULL;
> > > > +}
> > > > +
> > > >    static inline void reset_lrc_desc(struct intel_guc *guc, u32 id)
> > > >    {
> > > > -	struct guc_lrc_desc *desc = __get_lrc_desc(guc, id);
> > > > +	if (likely(guc_submission_initialized(guc))) {
> > > > +		struct guc_lrc_desc *desc = __get_lrc_desc(guc, id);
> > > > +		unsigned long flags;
> > > > -	memset(desc, 0, sizeof(*desc));
> > > > -	xa_erase_irq(&guc->context_lookup, id);
> > > > +		memset(desc, 0, sizeof(*desc));
> > > > +
> > > > +		/*
> > > > +		 * xarray API doesn't have xa_erase_irqsave wrapper, so calling
> > > > +		 * the lower level functions directly.
> > > > +		 */
> > > > +		xa_lock_irqsave(&guc->context_lookup, flags);
> > > > +		__xa_erase(&guc->context_lookup, id);
> > > > +		xa_unlock_irqrestore(&guc->context_lookup, flags);
> > > > +	}
> > > >    }
> > > >    static inline bool lrc_desc_registered(struct intel_guc *guc, u32 id)
> > > > @@ -260,7 +276,15 @@ static inline bool lrc_desc_registered(struct intel_guc *guc, u32 id)
> > > >    static inline void set_lrc_desc_registered(struct intel_guc *guc, u32 id,
> > > >    					   struct intel_context *ce)
> > > >    {
> > > > -	xa_store_irq(&guc->context_lookup, id, ce, GFP_ATOMIC);
> > > > +	unsigned long flags;
> > > > +
> > > > +	/*
> > > > +	 * xarray API doesn't have xa_save_irqsave wrapper, so calling the
> > > > +	 * lower level functions directly.
> > > > +	 */
> > > > +	xa_lock_irqsave(&guc->context_lookup, flags);
> > > > +	__xa_store(&guc->context_lookup, id, ce, GFP_ATOMIC);
> > > > +	xa_unlock_irqrestore(&guc->context_lookup, flags);
> > > >    }
> > > >    static int guc_submission_busy_loop(struct intel_guc* guc,
> > > > @@ -331,6 +355,8 @@ int intel_guc_wait_for_idle(struct intel_guc *guc, long timeout)
> > > >    					interruptible, timeout);
> > > >    }
> > > > +static int guc_lrc_desc_pin(struct intel_context *ce, bool loop);
> > > > +
> > > >    static int guc_add_request(struct intel_guc *guc, struct i915_request *rq)
> > > >    {
> > > >    	int err;
> > > > @@ -338,11 +364,22 @@ static int guc_add_request(struct intel_guc *guc, struct i915_request *rq)
> > > >    	u32 action[3];
> > > >    	int len = 0;
> > > >    	u32 g2h_len_dw = 0;
> > > > -	bool enabled = context_enabled(ce);
> > > > +	bool enabled;
> > > >    	GEM_BUG_ON(!atomic_read(&ce->guc_id_ref));
> > > >    	GEM_BUG_ON(context_guc_id_invalid(ce));
> > > > +	/*
> > > > +	 * Corner case where the GuC firmware was blown away and reloaded while
> > > > +	 * this context was pinned.
> > > > +	 */
> > > > +	if (unlikely(!lrc_desc_registered(guc, ce->guc_id))) {
> > > > +		err = guc_lrc_desc_pin(ce, false);
> > > > +		if (unlikely(err))
> > > > +			goto out;
> > > > +	}
> > > > +	enabled = context_enabled(ce);
> > > > +
> > > >    	if (!enabled) {
> > > >    		action[len++] = INTEL_GUC_ACTION_SCHED_CONTEXT_MODE_SET;
> > > >    		action[len++] = ce->guc_id;
> > > > @@ -365,6 +402,7 @@ static int guc_add_request(struct intel_guc *guc, struct i915_request *rq)
> > > >    		intel_context_put(ce);
> > > >    	}
> > > > +out:
> > > >    	return err;
> > > >    }
> > > > @@ -419,15 +457,10 @@ static int guc_dequeue_one_context(struct intel_guc *guc)
> > > >    	if (submit) {
> > > >    		guc_set_lrc_tail(last);
> > > >    resubmit:
> > > > -		/*
> > > > -		 * We only check for -EBUSY here even though it is possible for
> > > > -		 * -EDEADLK to be returned. If -EDEADLK is returned, the GuC has
> > > > -		 * died and a full GPU needs to be done. The hangcheck will
> > > > -		 * eventually detect that the GuC has died and trigger this
> > > > -		 * reset so no need to handle -EDEADLK here.
> > > > -		 */
> > > >    		ret = guc_add_request(guc, last);
> > > > -		if (ret == -EBUSY) {
> > > > +		if (unlikely(ret == -EIO))
> > > > +			goto deadlk;
> > > > +		else if (ret == -EBUSY) {
> > > >    			tasklet_schedule(&sched_engine->tasklet);
> > > >    			guc->stalled_request = last;
> > > >    			return false;
> > > > @@ -437,6 +470,11 @@ static int guc_dequeue_one_context(struct intel_guc *guc)
> > > >    	guc->stalled_request = NULL;
> > > >    	return submit;
> > > > +
> > > > +deadlk:
> > > > +	sched_engine->tasklet.callback = NULL;
> > > > +	tasklet_disable_nosync(&sched_engine->tasklet);
> > > > +	return false;
> > > >    }
> > > >    static void guc_submission_tasklet(struct tasklet_struct *t)
> > > > @@ -463,27 +501,165 @@ static void cs_irq_handler(struct intel_engine_cs *engine, u16 iir)
> > > >    		intel_engine_signal_breadcrumbs(engine);
> > > >    }
> > > > -static void guc_reset_prepare(struct intel_engine_cs *engine)
> > > > +static void __guc_context_destroy(struct intel_context *ce);
> > > > +static void release_guc_id(struct intel_guc *guc, struct intel_context *ce);
> > > > +static void guc_signal_context_fence(struct intel_context *ce);
> > > > +
> > > > +static void scrub_guc_desc_for_outstanding_g2h(struct intel_guc *guc)
> > > > +{
> > > > +	struct intel_context *ce;
> > > > +	unsigned long index, flags;
> > > > +	bool pending_disable, pending_enable, deregister, destroyed;
> > > > +
> > > > +	xa_for_each(&guc->context_lookup, index, ce) {
> > > > +		/* Flush context */
> > > > +		spin_lock_irqsave(&ce->guc_state.lock, flags);
> > > > +		spin_unlock_irqrestore(&ce->guc_state.lock, flags);
> > > > +
> > > > +		/*
> > > > +		 * Once we are at this point submission_disabled() is guaranteed
> > > > +		 * to visible to all callers who set the below flags (see above
> > > > +		 * flush and flushes in reset_prepare). If submission_disabled()
> > > > +		 * is set, the caller shouldn't set these flags.
> > > > +		 */
> > > > +
> > > > +		destroyed = context_destroyed(ce);
> > > > +		pending_enable = context_pending_enable(ce);
> > > > +		pending_disable = context_pending_disable(ce);
> > > > +		deregister = context_wait_for_deregister_to_register(ce);
> > > > +		init_sched_state(ce);
> > > > +
> > > > +		if (pending_enable || destroyed || deregister) {
> > > > +			atomic_dec(&guc->outstanding_submission_g2h);
> > > > +			if (deregister)
> > > > +				guc_signal_context_fence(ce);
> > > > +			if (destroyed) {
> > > > +				release_guc_id(guc, ce);
> > > > +				__guc_context_destroy(ce);
> > > > +			}
> > > > +			if (pending_enable|| deregister)
> > > > +				intel_context_put(ce);
> > > > +		}
> > > > +
> > > > +		/* Not mutualy exclusive with above if statement. */
> > > > +		if (pending_disable) {
> > > > +			guc_signal_context_fence(ce);
> > > > +			intel_context_sched_disable_unpin(ce);
> > > > +			atomic_dec(&guc->outstanding_submission_g2h);
> > > > +			intel_context_put(ce);
> > > > +		}
> > > > +	}
> > > > +}
> > > > +
> > > > +static inline bool
> > > > +submission_disabled(struct intel_guc *guc)
> > > > +{
> > > > +	struct i915_sched_engine * const sched_engine = guc->sched_engine;
> > > > +
> > > > +	return unlikely(!__tasklet_is_enabled(&sched_engine->tasklet));
> > > > +}
> > > > +
> > > > +static void disable_submission(struct intel_guc *guc)
> > > > +{
> > > > +	struct i915_sched_engine * const sched_engine = guc->sched_engine;
> > > > +
> > > > +	if (__tasklet_is_enabled(&sched_engine->tasklet)) {
> > > > +		GEM_BUG_ON(!guc->ct.enabled);
> > > > +		__tasklet_disable_sync_once(&sched_engine->tasklet);
> > > > +		sched_engine->tasklet.callback = NULL;
> > > > +	}
> > > > +}
> > > > +
> > > > +static void enable_submission(struct intel_guc *guc)
> > > > +{
> > > > +	struct i915_sched_engine * const sched_engine = guc->sched_engine;
> > > > +	unsigned long flags;
> > > > +
> > > > +	spin_lock_irqsave(&guc->sched_engine->lock, flags);
> > > > +	sched_engine->tasklet.callback = guc_submission_tasklet;
> > > > +	wmb();
> > > > +	if (!__tasklet_is_enabled(&sched_engine->tasklet) &&
> > > > +	    __tasklet_enable(&sched_engine->tasklet)) {
> > > > +		GEM_BUG_ON(!guc->ct.enabled);
> > > > +
> > > > +		/* And kick in case we missed a new request submission. */
> > > > +		tasklet_hi_schedule(&sched_engine->tasklet);
> > > > +	}
> > > > +	spin_unlock_irqrestore(&guc->sched_engine->lock, flags);
> > > > +}
> > > > +
> > > > +static void guc_flush_submissions(struct intel_guc *guc)
> > > >    {
> > > > -	ENGINE_TRACE(engine, "\n");
> > > > +	struct i915_sched_engine * const sched_engine = guc->sched_engine;
> > > > +	unsigned long flags;
> > > > +
> > > > +	spin_lock_irqsave(&sched_engine->lock, flags);
> > > > +	spin_unlock_irqrestore(&sched_engine->lock, flags);
> > > > +}
> > > > +
> > > > +void intel_guc_submission_reset_prepare(struct intel_guc *guc)
> > > > +{
> > > > +	int i;
> > > > +
> > > > +	if (unlikely(!guc_submission_initialized(guc)))
> > > > +		/* Reset called during driver load? GuC not yet initialised! */
> > > > +		return;
> > > > +
> > > > +	disable_submission(guc);
> > > > +	guc->interrupts.disable(guc);
> > > > +
> > > > +	/* Flush IRQ handler */
> > > > +	spin_lock_irq(&guc_to_gt(guc)->irq_lock);
> > > > +	spin_unlock_irq(&guc_to_gt(guc)->irq_lock);
> > > > +
> > > > +	guc_flush_submissions(guc);
> > > >    	/*
> > > > -	 * Prevent request submission to the hardware until we have
> > > > -	 * completed the reset in i915_gem_reset_finish(). If a request
> > > > -	 * is completed by one engine, it may then queue a request
> > > > -	 * to a second via its execlists->tasklet *just* as we are
> > > > -	 * calling engine->init_hw() and also writing the ELSP.
> > > > -	 * Turning off the execlists->tasklet until the reset is over
> > > > -	 * prevents the race.
> > > > -	 */
> > > > -	__tasklet_disable_sync_once(&engine->sched_engine->tasklet);
> > > > +	 * Handle any outstanding G2Hs before reset. Call IRQ handler directly
> > > > +	 * each pass as interrupt have been disabled. We always scrub for
> > > > +	 * outstanding G2H as it is possible for outstanding_submission_g2h to
> > > > +	 * be incremented after the context state update.
> > > > + 	 */
> > > > +	for (i = 0; i < 4 && atomic_read(&guc->outstanding_submission_g2h); ++i) {
> > > > +		intel_guc_to_host_event_handler(guc);
> > > > +#define wait_for_reset(guc, wait_var) \
> > > > +		guc_wait_for_pending_msg(guc, wait_var, false, (HZ / 20))
> > > > +		do {
> > > > +			wait_for_reset(guc, &guc->outstanding_submission_g2h);
> > > > +		} while (!list_empty(&guc->ct.requests.incoming));
> > > > +	}
> > > > +	scrub_guc_desc_for_outstanding_g2h(guc);
> > > >    }
> > > > -static void guc_reset_state(struct intel_context *ce,
> > > > -			    struct intel_engine_cs *engine,
> > > > -			    u32 head,
> > > > -			    bool scrub)
> > > > +static struct intel_engine_cs *
> > > > +guc_virtual_get_sibling(struct intel_engine_cs *ve, unsigned int sibling)
> > > >    {
> > > > +	struct intel_engine_cs *engine;
> > > > +	intel_engine_mask_t tmp, mask = ve->mask;
> > > > +	unsigned int num_siblings = 0;
> > > > +
> > > > +	for_each_engine_masked(engine, ve->gt, mask, tmp)
> > > > +		if (num_siblings++ == sibling)
> > > > +			return engine;
> > > > +
> > > > +	return NULL;
> > > > +}
> > > > +
> > > > +static inline struct intel_engine_cs *
> > > > +__context_to_physical_engine(struct intel_context *ce)
> > > > +{
> > > > +	struct intel_engine_cs *engine = ce->engine;
> > > > +
> > > > +	if (intel_engine_is_virtual(engine))
> > > > +		engine = guc_virtual_get_sibling(engine, 0);
> > > > +
> > > > +	return engine;
> > > > +}
> > > > +
> > > > +static void guc_reset_state(struct intel_context *ce, u32 head, bool scrub)
> > > > +{
> > > > +	struct intel_engine_cs *engine = __context_to_physical_engine(ce);
> > > > +
> > > >    	GEM_BUG_ON(!intel_context_is_pinned(ce));
> > > >    	/*
> > > > @@ -501,42 +677,147 @@ static void guc_reset_state(struct intel_context *ce,
> > > >    	lrc_update_regs(ce, engine, head);
> > > >    }
> > > > -static void guc_reset_rewind(struct intel_engine_cs *engine, bool stalled)
> > > > +static void guc_reset_nop(struct intel_engine_cs *engine)
> > > >    {
> > > > -	struct intel_engine_execlists * const execlists = &engine->execlists;
> > > > -	struct i915_request *rq;
> > > > +}
> > > > +
> > > > +static void guc_rewind_nop(struct intel_engine_cs *engine, bool stalled)
> > > > +{
> > > > +}
> > > > +
> > > > +static void
> > > > +__unwind_incomplete_requests(struct intel_context *ce)
> > > > +{
> > > > +	struct i915_request *rq, *rn;
> > > > +	struct list_head *pl;
> > > > +	int prio = I915_PRIORITY_INVALID;
> > > > +	struct i915_sched_engine * const sched_engine =
> > > > +		ce->engine->sched_engine;
> > > >    	unsigned long flags;
> > > > -	spin_lock_irqsave(&engine->sched_engine->lock, flags);
> > > > +	spin_lock_irqsave(&sched_engine->lock, flags);
> > > > +	spin_lock(&ce->guc_active.lock);
> > > > +	list_for_each_entry_safe(rq, rn,
> > > > +				 &ce->guc_active.requests,
> > > > +				 sched.link) {
> > > > +		if (i915_request_completed(rq))
> > > > +			continue;
> > > > +
> > > > +		list_del_init(&rq->sched.link);
> > > > +		spin_unlock(&ce->guc_active.lock);
> > > > +
> > > > +		__i915_request_unsubmit(rq);
> > > > +
> > > > +		/* Push the request back into the queue for later resubmission. */
> > > > +		GEM_BUG_ON(rq_prio(rq) == I915_PRIORITY_INVALID);
> > > > +		if (rq_prio(rq) != prio) {
> > > > +			prio = rq_prio(rq);
> > > > +			pl = i915_sched_lookup_priolist(sched_engine, prio);
> > > > +		}
> > > > +		GEM_BUG_ON(i915_sched_engine_is_empty(sched_engine));
> > > > +
> > > > +		list_add_tail(&rq->sched.link, pl);
> > > > +		set_bit(I915_FENCE_FLAG_PQUEUE, &rq->fence.flags);
> > > > -	/* Push back any incomplete requests for replay after the reset. */
> > > > -	rq = execlists_unwind_incomplete_requests(execlists);
> > > > -	if (!rq)
> > > > -		goto out_unlock;
> > > > +		spin_lock(&ce->guc_active.lock);
> > > > +	}
> > > > +	spin_unlock(&ce->guc_active.lock);
> > > > +	spin_unlock_irqrestore(&sched_engine->lock, flags);
> > > > +}
> > > > +
> > > > +static struct i915_request *context_find_active_request(struct intel_context *ce)
> > > > +{
> > > > +	struct i915_request *rq, *active = NULL;
> > > > +	unsigned long flags;
> > > > +
> > > > +	spin_lock_irqsave(&ce->guc_active.lock, flags);
> > > > +	list_for_each_entry_reverse(rq, &ce->guc_active.requests,
> > > > +				    sched.link) {
> > > > +		if (i915_request_completed(rq))
> > > > +			break;
> > > > +
> > > > +		active = rq;
> > > > +	}
> > > > +	spin_unlock_irqrestore(&ce->guc_active.lock, flags);
> > > > +
> > > > +	return active;
> > > > +}
> > > > +
> > > > +static void __guc_reset_context(struct intel_context *ce, bool stalled)
> > > > +{
> > > > +	struct i915_request *rq;
> > > > +	u32 head;
> > > > +
> > > > +	/*
> > > > +	 * GuC will implicitly mark the context as non-schedulable
> > > > +	 * when it sends the reset notification. Make sure our state
> > > > +	 * reflects this change. The context will be marked enabled
> > > > +	 * on resubmission.
> > > > +	 */
> > > > +	clr_context_enabled(ce);
> > > > +
> > > > +	rq = context_find_active_request(ce);
> > > > +	if (!rq) {
> > > > +		head = ce->ring->tail;
> > > > +		stalled = false;
> > > > +		goto out_replay;
> > > > +	}
> > > >    	if (!i915_request_started(rq))
> > > >    		stalled = false;
> > > > +	GEM_BUG_ON(i915_active_is_idle(&ce->active));
> > > > +	head = intel_ring_wrap(ce->ring, rq->head);
> > > >    	__i915_request_reset(rq, stalled);
> > > > -	guc_reset_state(rq->context, engine, rq->head, stalled);
> > > > -out_unlock:
> > > > -	spin_unlock_irqrestore(&engine->sched_engine->lock, flags);
> > > > +out_replay:
> > > > +	guc_reset_state(ce, head, stalled);
> > > > +	__unwind_incomplete_requests(ce);
> > > >    }
> > > > -static void guc_reset_cancel(struct intel_engine_cs *engine)
> > > > +void intel_guc_submission_reset(struct intel_guc *guc, bool stalled)
> > > > +{
> > > > +	struct intel_context *ce;
> > > > +	unsigned long index;
> > > > +
> > > > +	if (unlikely(!guc_submission_initialized(guc)))
> > > > +		/* Reset called during driver load? GuC not yet initialised! */
> > > > +		return;
> > > > +
> > > > +	xa_for_each(&guc->context_lookup, index, ce)
> > > > +		if (intel_context_is_pinned(ce))
> > > > +			__guc_reset_context(ce, stalled);
> > > > +
> > > > +	/* GuC is blown away, drop all references to contexts */
> > > > +	xa_destroy(&guc->context_lookup);
> > > > +}
> > > > +
> > > > +static void guc_cancel_context_requests(struct intel_context *ce)
> > > > +{
> > > > +	struct i915_sched_engine *sched_engine = ce_to_guc(ce)->sched_engine;
> > > > +	struct i915_request *rq;
> > > > +	unsigned long flags;
> > > > +
> > > > +	/* Mark all executing requests as skipped. */
> > > > +	spin_lock_irqsave(&sched_engine->lock, flags);
> > > > +	spin_lock(&ce->guc_active.lock);
> > > > +	list_for_each_entry(rq, &ce->guc_active.requests, sched.link)
> > > > +		i915_request_put(i915_request_mark_eio(rq));
> > > > +	spin_unlock(&ce->guc_active.lock);
> > > > +	spin_unlock_irqrestore(&sched_engine->lock, flags);
> > > > +}
> > > > +
> > > > +static void
> > > > +guc_cancel_sched_engine_requests(struct i915_sched_engine *sched_engine)
> > > >    {
> > > > -	struct i915_sched_engine * const sched_engine = engine->sched_engine;
> > > >    	struct i915_request *rq, *rn;
> > > >    	struct rb_node *rb;
> > > >    	unsigned long flags;
> > > >    	/* Can be called during boot if GuC fails to load */
> > > > -	if (!engine->gt)
> > > > +	if (!sched_engine)
> > > >    		return;
> > > > -	ENGINE_TRACE(engine, "\n");
> > > > -
> > > >    	/*
> > > >    	 * Before we call engine->cancel_requests(), we should have exclusive
> > > >    	 * access to the submission state. This is arranged for us by the
> > > > @@ -553,21 +834,16 @@ static void guc_reset_cancel(struct intel_engine_cs *engine)
> > > >    	 */
> > > >    	spin_lock_irqsave(&sched_engine->lock, flags);
> > > > -	/* Mark all executing requests as skipped. */
> > > > -	list_for_each_entry(rq, &sched_engine->requests, sched.link) {
> > > > -		i915_request_set_error_once(rq, -EIO);
> > > > -		i915_request_mark_complete(rq);
> > > > -	}
> > > > -
> > > >    	/* Flush the queued requests to the timeline list (for retiring). */
> > > >    	while ((rb = rb_first_cached(&sched_engine->queue))) {
> > > >    		struct i915_priolist *p = to_priolist(rb);
> > > >    		priolist_for_each_request_consume(rq, rn, p) {
> > > >    			list_del_init(&rq->sched.link);
> > > > +
> > > >    			__i915_request_submit(rq);
> > > > -			dma_fence_set_error(&rq->fence, -EIO);
> > > > -			i915_request_mark_complete(rq);
> > > > +
> > > > +			i915_request_put(i915_request_mark_eio(rq));
> > > >    		}
> > > >    		rb_erase_cached(&p->node, &sched_engine->queue);
> > > > @@ -582,14 +858,38 @@ static void guc_reset_cancel(struct intel_engine_cs *engine)
> > > >    	spin_unlock_irqrestore(&sched_engine->lock, flags);
> > > >    }
> > > > -static void guc_reset_finish(struct intel_engine_cs *engine)
> > > > +void intel_guc_submission_cancel_requests(struct intel_guc *guc)
> > > >    {
> > > > -	if (__tasklet_enable(&engine->sched_engine->tasklet))
> > > > -		/* And kick in case we missed a new request submission. */
> > > > -		tasklet_hi_schedule(&engine->sched_engine->tasklet);
> > > > +	struct intel_context *ce;
> > > > +	unsigned long index;
> > > > +
> > > > +	xa_for_each(&guc->context_lookup, index, ce)
> > > > +		if (intel_context_is_pinned(ce))
> > > > +			guc_cancel_context_requests(ce);
> > > > -	ENGINE_TRACE(engine, "depth->%d\n",
> > > > -		     atomic_read(&engine->sched_engine->tasklet.count));
> > > > +	guc_cancel_sched_engine_requests(guc->sched_engine);
> > > > +
> > > > +	/* GuC is blown away, drop all references to contexts */
> > > > +	xa_destroy(&guc->context_lookup);
> > > > +}
> > > > +
> > > > +void intel_guc_submission_reset_finish(struct intel_guc *guc)
> > > > +{
> > > > +	/* Reset called during driver load or during wedge? */
> > > > +	if (unlikely(!guc_submission_initialized(guc) ||
> > > > +		     test_bit(I915_WEDGED, &guc_to_gt(guc)->reset.flags)))
> > > > +		return;
> > > > +
> > > > +	/*
> > > > +	 * Technically possible for either of these values to be non-zero here,
> > > > +	 * but very unlikely + harmless. Regardless let's add a warn so we can
> > > > +	 * see in CI if this happens frequently / a precursor to taking down the
> > > > +	 * machine.
> > > > +	 */
> > > > +	GEM_WARN_ON(atomic_read(&guc->outstanding_submission_g2h));
> > > > +	atomic_set(&guc->outstanding_submission_g2h, 0);
> > > > +
> > > > +	enable_submission(guc);
> > > >    }
> > > >    /*
> > > > @@ -656,6 +956,9 @@ static int guc_bypass_tasklet_submit(struct intel_guc *guc,
> > > >    	else
> > > >    		trace_i915_request_guc_submit(rq);
> > > > +	if (unlikely(ret == -EIO))
> > > > +		disable_submission(guc);
> > > > +
> > > >    	return ret;
> > > >    }
> > > > @@ -668,7 +971,8 @@ static void guc_submit_request(struct i915_request *rq)
> > > >    	/* Will be called from irq-context when using foreign fences. */
> > > >    	spin_lock_irqsave(&sched_engine->lock, flags);
> > > > -	if (guc->stalled_request || !i915_sched_engine_is_empty(sched_engine))
> > > > +	if (submission_disabled(guc) || guc->stalled_request ||
> > > > +	    !i915_sched_engine_is_empty(sched_engine))
> > > >    		queue_request(sched_engine, rq, rq_prio(rq));
> > > >    	else if (guc_bypass_tasklet_submit(guc, rq) == -EBUSY)
> > > >    		tasklet_hi_schedule(&sched_engine->tasklet);
> > > > @@ -805,7 +1109,8 @@ static void unpin_guc_id(struct intel_guc *guc, struct intel_context *ce)
> > > >    static int __guc_action_register_context(struct intel_guc *guc,
> > > >    					 u32 guc_id,
> > > > -					 u32 offset)
> > > > +					 u32 offset,
> > > > +					 bool loop)
> > > >    {
> > > >    	u32 action[] = {
> > > >    		INTEL_GUC_ACTION_REGISTER_CONTEXT,
> > > > @@ -813,10 +1118,10 @@ static int __guc_action_register_context(struct intel_guc *guc,
> > > >    		offset,
> > > >    	};
> > > > -	return guc_submission_busy_loop(guc, action, ARRAY_SIZE(action), 0, true);
> > > > +	return guc_submission_busy_loop(guc, action, ARRAY_SIZE(action), 0, loop);
> > > >    }
> > > > -static int register_context(struct intel_context *ce)
> > > > +static int register_context(struct intel_context *ce, bool loop)
> > > >    {
> > > >    	struct intel_guc *guc = ce_to_guc(ce);
> > > >    	u32 offset = intel_guc_ggtt_offset(guc, guc->lrc_desc_pool) +
> > > > @@ -824,11 +1129,12 @@ static int register_context(struct intel_context *ce)
> > > >    	trace_intel_context_register(ce);
> > > > -	return __guc_action_register_context(guc, ce->guc_id, offset);
> > > > +	return __guc_action_register_context(guc, ce->guc_id, offset, loop);
> > > >    }
> > > >    static int __guc_action_deregister_context(struct intel_guc *guc,
> > > > -					   u32 guc_id)
> > > > +					   u32 guc_id,
> > > > +					   bool loop)
> > > >    {
> > > >    	u32 action[] = {
> > > >    		INTEL_GUC_ACTION_DEREGISTER_CONTEXT,
> > > > @@ -836,16 +1142,16 @@ static int __guc_action_deregister_context(struct intel_guc *guc,
> > > >    	};
> > > >    	return guc_submission_busy_loop(guc, action, ARRAY_SIZE(action),
> > > > -					G2H_LEN_DW_DEREGISTER_CONTEXT, true);
> > > > +					G2H_LEN_DW_DEREGISTER_CONTEXT, loop);
> > > >    }
> > > > -static int deregister_context(struct intel_context *ce, u32 guc_id)
> > > > +static int deregister_context(struct intel_context *ce, u32 guc_id, bool loop)
> > > >    {
> > > >    	struct intel_guc *guc = ce_to_guc(ce);
> > > >    	trace_intel_context_deregister(ce);
> > > > -	return __guc_action_deregister_context(guc, guc_id);
> > > > +	return __guc_action_deregister_context(guc, guc_id, loop);
> > > >    }
> > > >    static intel_engine_mask_t adjust_engine_mask(u8 class, intel_engine_mask_t mask)
> > > > @@ -874,7 +1180,7 @@ static void guc_context_policy_init(struct intel_engine_cs *engine,
> > > >    	desc->preemption_timeout = CONTEXT_POLICY_DEFAULT_PREEMPTION_TIME_US;
> > > >    }
> > > > -static int guc_lrc_desc_pin(struct intel_context *ce)
> > > > +static int guc_lrc_desc_pin(struct intel_context *ce, bool loop)
> > > >    {
> > > >    	struct intel_runtime_pm *runtime_pm =
> > > >    		&ce->engine->gt->i915->runtime_pm;
> > > > @@ -920,18 +1226,44 @@ static int guc_lrc_desc_pin(struct intel_context *ce)
> > > >    	 */
> > > >    	if (context_registered) {
> > > >    		trace_intel_context_steal_guc_id(ce);
> > > > -		set_context_wait_for_deregister_to_register(ce);
> > > > -		intel_context_get(ce);
> > > > +		if (!loop) {
> > > > +			set_context_wait_for_deregister_to_register(ce);
> > > > +			intel_context_get(ce);
> > > > +		} else {
> > > > +			bool disabled;
> > > > +			unsigned long flags;
> > > > +
> > > > +			/* Seal race with Reset */
> > > > +			spin_lock_irqsave(&ce->guc_state.lock, flags);
> > > > +			disabled = submission_disabled(guc);
> > > > +			if (likely(!disabled)) {
> > > > +				set_context_wait_for_deregister_to_register(ce);
> > > > +				intel_context_get(ce);
> > > > +			}
> > > > +			spin_unlock_irqrestore(&ce->guc_state.lock, flags);
> > > > +			if (unlikely(disabled)) {
> > > > +				reset_lrc_desc(guc, desc_idx);
> > > > +				return 0;	/* Will get registered later */
> > > > +			}
> > > > +		}
> > > >    		/*
> > > >    		 * If stealing the guc_id, this ce has the same guc_id as the
> > > >    		 * context whos guc_id was stole.
> > > >    		 */
> > > >    		with_intel_runtime_pm(runtime_pm, wakeref)
> > > > -			ret = deregister_context(ce, ce->guc_id);
> > > > +			ret = deregister_context(ce, ce->guc_id, loop);
> > > > +		if (unlikely(ret == -EBUSY)) {
> > > > +			clr_context_wait_for_deregister_to_register(ce);
> > > > +			intel_context_put(ce);
> > > > +		}
> > > >    	} else {
> > > >    		with_intel_runtime_pm(runtime_pm, wakeref)
> > > > -			ret = register_context(ce);
> > > > +			ret = register_context(ce, loop);
> > > > +		if (unlikely(ret == -EBUSY))
> > > > +			reset_lrc_desc(guc, desc_idx);
> > > > +		else if (unlikely(ret == -ENODEV))
> > > > +			ret = 0;	/* Will get registered later */
> > > >    	}
> > > >    	return ret;
> > > > @@ -994,7 +1326,6 @@ static void __guc_context_sched_disable(struct intel_guc *guc,
> > > >    	GEM_BUG_ON(guc_id == GUC_INVALID_LRC_ID);
> > > >    	trace_intel_context_sched_disable(ce);
> > > > -	intel_context_get(ce);
> > > >    	guc_submission_busy_loop(guc, action, ARRAY_SIZE(action),
> > > >    				 G2H_LEN_DW_SCHED_CONTEXT_MODE_SET, true);
> > > > @@ -1004,6 +1335,7 @@ static u16 prep_context_pending_disable(struct intel_context *ce)
> > > >    {
> > > >    	set_context_pending_disable(ce);
> > > >    	clr_context_enabled(ce);
> > > > +	intel_context_get(ce);
> > > >    	return ce->guc_id;
> > > >    }
> > > > @@ -1016,7 +1348,7 @@ static void guc_context_sched_disable(struct intel_context *ce)
> > > >    	u16 guc_id;
> > > >    	intel_wakeref_t wakeref;
> > > > -	if (context_guc_id_invalid(ce) ||
> > > > +	if (submission_disabled(guc) || context_guc_id_invalid(ce) ||
> > > >    	    !lrc_desc_registered(guc, ce->guc_id)) {
> > > >    		clr_context_enabled(ce);
> > > >    		goto unpin;
> > > > @@ -1034,6 +1366,7 @@ static void guc_context_sched_disable(struct intel_context *ce)
> > > >    	 * request doesn't slip through the 'context_pending_disable' fence.
> > > >    	 */
> > > >    	if (unlikely(atomic_add_unless(&ce->pin_count, -2, 2))) {
> > > > +		spin_unlock_irqrestore(&ce->guc_state.lock, flags);
> > > >    		return;
> > > >    	}
> > > >    	guc_id = prep_context_pending_disable(ce);
> > > > @@ -1050,19 +1383,13 @@ static void guc_context_sched_disable(struct intel_context *ce)
> > > >    static inline void guc_lrc_desc_unpin(struct intel_context *ce)
> > > >    {
> > > > -	struct intel_engine_cs *engine = ce->engine;
> > > > -	struct intel_guc *guc = &engine->gt->uc.guc;
> > > > -	unsigned long flags;
> > > > +	struct intel_guc *guc = ce_to_guc(ce);
> > > >    	GEM_BUG_ON(!lrc_desc_registered(guc, ce->guc_id));
> > > >    	GEM_BUG_ON(ce != __get_context(guc, ce->guc_id));
> > > >    	GEM_BUG_ON(context_enabled(ce));
> > > > -	spin_lock_irqsave(&ce->guc_state.lock, flags);
> > > > -	set_context_destroyed(ce);
> > > > -	spin_unlock_irqrestore(&ce->guc_state.lock, flags);
> > > > -
> > > > -	deregister_context(ce, ce->guc_id);
> > > > +	deregister_context(ce, ce->guc_id, true);
> > > >    }
> > > >    static void __guc_context_destroy(struct intel_context *ce)
> > > > @@ -1090,13 +1417,15 @@ static void guc_context_destroy(struct kref *kref)
> > > >    	struct intel_guc *guc = &ce->engine->gt->uc.guc;
> > > >    	intel_wakeref_t wakeref;
> > > >    	unsigned long flags;
> > > > +	bool disabled;
> > > >    	/*
> > > >    	 * If the guc_id is invalid this context has been stolen and we can free
> > > >    	 * it immediately. Also can be freed immediately if the context is not
> > > >    	 * registered with the GuC.
> > > >    	 */
> > > > -	if (context_guc_id_invalid(ce) ||
> > > > +	if (submission_disabled(guc) ||
> > > > +	    context_guc_id_invalid(ce) ||
> > > >    	    !lrc_desc_registered(guc, ce->guc_id)) {
> > > >    		release_guc_id(guc, ce);
> > > >    		__guc_context_destroy(ce);
> > > > @@ -1123,6 +1452,18 @@ static void guc_context_destroy(struct kref *kref)
> > > >    		list_del_init(&ce->guc_id_link);
> > > >    	spin_unlock_irqrestore(&guc->contexts_lock, flags);
> > > > +	/* Seal race with Reset */
> > > > +	spin_lock_irqsave(&ce->guc_state.lock, flags);
> > > > +	disabled = submission_disabled(guc);
> > > > +	if (likely(!disabled))
> > > > +		set_context_destroyed(ce);
> > > > +	spin_unlock_irqrestore(&ce->guc_state.lock, flags);
> > > > +	if (unlikely(disabled)) {
> > > > +		release_guc_id(guc, ce);
> > > > +		__guc_context_destroy(ce);
> > > > +		return;
> > > > +	}
> > > > +
> > > >    	/*
> > > >    	 * We defer GuC context deregistration until the context is destroyed
> > > >    	 * in order to save on CTBs. With this optimization ideally we only need
> > > > @@ -1145,6 +1486,33 @@ static int guc_context_alloc(struct intel_context *ce)
> > > >    	return lrc_alloc(ce, ce->engine);
> > > >    }
> > > > +static void add_to_context(struct i915_request *rq)
> > > > +{
> > > > +	struct intel_context *ce = rq->context;
> > > > +
> > > > +	spin_lock(&ce->guc_active.lock);
> > > > +	list_move_tail(&rq->sched.link, &ce->guc_active.requests);
> > > > +	spin_unlock(&ce->guc_active.lock);
> > > > +}
> > > > +
> > > > +static void remove_from_context(struct i915_request *rq)
> > > > +{
> > > > +	struct intel_context *ce = rq->context;
> > > > +
> > > > +	spin_lock_irq(&ce->guc_active.lock);
> > > > +
> > > > +	list_del_init(&rq->sched.link);
> > > > +	clear_bit(I915_FENCE_FLAG_PQUEUE, &rq->fence.flags);
> > > > +
> > > > +	/* Prevent further __await_execution() registering a cb, then flush */
> > > > +	set_bit(I915_FENCE_FLAG_ACTIVE, &rq->fence.flags);
> > > > +
> > > > +	spin_unlock_irq(&ce->guc_active.lock);
> > > > +
> > > > +	atomic_dec(&ce->guc_id_ref);
> > > > +	i915_request_notify_execute_cb_imm(rq);
> > > > +}
> > > > +
> > > >    static const struct intel_context_ops guc_context_ops = {
> > > >    	.alloc = guc_context_alloc,
> > > > @@ -1183,8 +1551,6 @@ static void guc_signal_context_fence(struct intel_context *ce)
> > > >    {
> > > >    	unsigned long flags;
> > > > -	GEM_BUG_ON(!context_wait_for_deregister_to_register(ce));
> > > > -
> > > >    	spin_lock_irqsave(&ce->guc_state.lock, flags);
> > > >    	clr_context_wait_for_deregister_to_register(ce);
> > > >    	__guc_signal_context_fence(ce);
> > > > @@ -1193,8 +1559,9 @@ static void guc_signal_context_fence(struct intel_context *ce)
> > > >    static bool context_needs_register(struct intel_context *ce, bool new_guc_id)
> > > >    {
> > > > -	return new_guc_id || test_bit(CONTEXT_LRCA_DIRTY, &ce->flags) ||
> > > > -		!lrc_desc_registered(ce_to_guc(ce), ce->guc_id);
> > > > +	return (new_guc_id || test_bit(CONTEXT_LRCA_DIRTY, &ce->flags) ||
> > > > +		!lrc_desc_registered(ce_to_guc(ce), ce->guc_id)) &&
> > > > +		!submission_disabled(ce_to_guc(ce));
> > > >    }
> > > >    static int guc_request_alloc(struct i915_request *rq)
> > > > @@ -1252,8 +1619,12 @@ static int guc_request_alloc(struct i915_request *rq)
> > > >    	if (unlikely(ret < 0))
> > > >    		return ret;;
> > > >    	if (context_needs_register(ce, !!ret)) {
> > > > -		ret = guc_lrc_desc_pin(ce);
> > > > +		ret = guc_lrc_desc_pin(ce, true);
> > > >    		if (unlikely(ret)) {	/* unwind */
> > > > +			if (ret == -EIO) {
> > > > +				disable_submission(guc);
> > > > +				goto out;	/* GPU will be reset */
> > > > +			}
> > > >    			atomic_dec(&ce->guc_id_ref);
> > > >    			unpin_guc_id(guc, ce);
> > > >    			return ret;
> > > > @@ -1290,20 +1661,6 @@ static int guc_request_alloc(struct i915_request *rq)
> > > >    	return 0;
> > > >    }
> > > > -static struct intel_engine_cs *
> > > > -guc_virtual_get_sibling(struct intel_engine_cs *ve, unsigned int sibling)
> > > > -{
> > > > -	struct intel_engine_cs *engine;
> > > > -	intel_engine_mask_t tmp, mask = ve->mask;
> > > > -	unsigned int num_siblings = 0;
> > > > -
> > > > -	for_each_engine_masked(engine, ve->gt, mask, tmp)
> > > > -		if (num_siblings++ == sibling)
> > > > -			return engine;
> > > > -
> > > > -	return NULL;
> > > > -}
> > > > -
> > > >    static int guc_virtual_context_pre_pin(struct intel_context *ce,
> > > >    				       struct i915_gem_ww_ctx *ww,
> > > >    				       void **vaddr)
> > > > @@ -1512,7 +1869,7 @@ static inline void guc_kernel_context_pin(struct intel_guc *guc,
> > > >    {
> > > >    	if (context_guc_id_invalid(ce))
> > > >    		pin_guc_id(guc, ce);
> > > > -	guc_lrc_desc_pin(ce);
> > > > +	guc_lrc_desc_pin(ce, true);
> > > >    }
> > > >    static inline void guc_init_lrc_mapping(struct intel_guc *guc)
> > > > @@ -1578,13 +1935,15 @@ static void guc_default_vfuncs(struct intel_engine_cs *engine)
> > > >    	engine->cops = &guc_context_ops;
> > > >    	engine->request_alloc = guc_request_alloc;
> > > >    	engine->bump_serial = guc_bump_serial;
> > > > +	engine->add_active_request = add_to_context;
> > > > +	engine->remove_active_request = remove_from_context;
> > > >    	engine->sched_engine->schedule = i915_schedule;
> > > > -	engine->reset.prepare = guc_reset_prepare;
> > > > -	engine->reset.rewind = guc_reset_rewind;
> > > > -	engine->reset.cancel = guc_reset_cancel;
> > > > -	engine->reset.finish = guc_reset_finish;
> > > > +	engine->reset.prepare = guc_reset_nop;
> > > > +	engine->reset.rewind = guc_rewind_nop;
> > > > +	engine->reset.cancel = guc_reset_nop;
> > > > +	engine->reset.finish = guc_reset_nop;
> > > >    	engine->emit_flush = gen8_emit_flush_xcs;
> > > >    	engine->emit_init_breadcrumb = gen8_emit_init_breadcrumb;
> > > > @@ -1757,7 +2116,7 @@ int intel_guc_deregister_done_process_msg(struct intel_guc *guc,
> > > >    		 * register this context.
> > > >    		 */
> > > >    		with_intel_runtime_pm(runtime_pm, wakeref)
> > > > -			register_context(ce);
> > > > +			register_context(ce, true);
> > > >    		guc_signal_context_fence(ce);
> > > >    		intel_context_put(ce);
> > > >    	} else if (context_destroyed(ce)) {
> > > > @@ -1939,6 +2298,10 @@ guc_create_virtual(struct intel_engine_cs **siblings, unsigned int count)
> > > >    				 "v%dx%d", ve->base.class, count);
> > > >    			ve->base.context_size = sibling->context_size;
> > > > +			ve->base.add_active_request =
> > > > +				sibling->add_active_request;
> > > > +			ve->base.remove_active_request =
> > > > +				sibling->remove_active_request;
> > > >    			ve->base.emit_bb_start = sibling->emit_bb_start;
> > > >    			ve->base.emit_flush = sibling->emit_flush;
> > > >    			ve->base.emit_init_breadcrumb =
> > > > diff --git a/drivers/gpu/drm/i915/gt/uc/intel_uc.c b/drivers/gpu/drm/i915/gt/uc/intel_uc.c
> > > > index 6d8b9233214e..f0b02200aa01 100644
> > > > --- a/drivers/gpu/drm/i915/gt/uc/intel_uc.c
> > > > +++ b/drivers/gpu/drm/i915/gt/uc/intel_uc.c
> > > > @@ -565,12 +565,49 @@ void intel_uc_reset_prepare(struct intel_uc *uc)
> > > >    {
> > > >    	struct intel_guc *guc = &uc->guc;
> > > > -	if (!intel_guc_is_ready(guc))
> > > > +
> > > > +	/* Nothing to do if GuC isn't supported */
> > > > +	if (!intel_uc_supports_guc(uc))
> > > >    		return;
> > > > +	/* Firmware expected to be running when this function is called */
> > > > +	if (!intel_guc_is_ready(guc))
> > > > +		goto sanitize;
> > > > +
> > > > +	if (intel_uc_uses_guc_submission(uc))
> > > > +		intel_guc_submission_reset_prepare(guc);
> > > > +
> > > > +sanitize:
> > > >    	__uc_sanitize(uc);
> > > >    }
> > > > +void intel_uc_reset(struct intel_uc *uc, bool stalled)
> > > > +{
> > > > +	struct intel_guc *guc = &uc->guc;
> > > > +
> > > > +	/* Firmware can not be running when this function is called  */
> > > > +	if (intel_uc_uses_guc_submission(uc))
> > > > +		intel_guc_submission_reset(guc, stalled);
> > > > +}
> > > > +
> > > > +void intel_uc_reset_finish(struct intel_uc *uc)
> > > > +{
> > > > +	struct intel_guc *guc = &uc->guc;
> > > > +
> > > > +	/* Firmware expected to be running when this function is called */
> > > > +	if (intel_guc_is_fw_running(guc) && intel_uc_uses_guc_submission(uc))
> > > > +		intel_guc_submission_reset_finish(guc);
> > > > +}
> > > > +
> > > > +void intel_uc_cancel_requests(struct intel_uc *uc)
> > > > +{
> > > > +	struct intel_guc *guc = &uc->guc;
> > > > +
> > > > +	/* Firmware can not be running when this function is called  */
> > > > +	if (intel_uc_uses_guc_submission(uc))
> > > > +		intel_guc_submission_cancel_requests(guc);
> > > > +}
> > > > +
> > > >    void intel_uc_runtime_suspend(struct intel_uc *uc)
> > > >    {
> > > >    	struct intel_guc *guc = &uc->guc;
> > > > diff --git a/drivers/gpu/drm/i915/gt/uc/intel_uc.h b/drivers/gpu/drm/i915/gt/uc/intel_uc.h
> > > > index c4cef885e984..eaa3202192ac 100644
> > > > --- a/drivers/gpu/drm/i915/gt/uc/intel_uc.h
> > > > +++ b/drivers/gpu/drm/i915/gt/uc/intel_uc.h
> > > > @@ -37,6 +37,9 @@ void intel_uc_driver_late_release(struct intel_uc *uc);
> > > >    void intel_uc_driver_remove(struct intel_uc *uc);
> > > >    void intel_uc_init_mmio(struct intel_uc *uc);
> > > >    void intel_uc_reset_prepare(struct intel_uc *uc);
> > > > +void intel_uc_reset(struct intel_uc *uc, bool stalled);
> > > > +void intel_uc_reset_finish(struct intel_uc *uc);
> > > > +void intel_uc_cancel_requests(struct intel_uc *uc);
> > > >    void intel_uc_suspend(struct intel_uc *uc);
> > > >    void intel_uc_runtime_suspend(struct intel_uc *uc);
> > > >    int intel_uc_resume(struct intel_uc *uc);
> > > > diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
> > > > index dec5a35c9aa2..192784875a1d 100644
> > > > --- a/drivers/gpu/drm/i915/i915_request.c
> > > > +++ b/drivers/gpu/drm/i915/i915_request.c
> > > > @@ -194,7 +194,7 @@ static bool irq_work_imm(struct irq_work *wrk)
> > > >    	return false;
> > > >    }
> > > > -static void __notify_execute_cb_imm(struct i915_request *rq)
> > > > +void i915_request_notify_execute_cb_imm(struct i915_request *rq)
> > > >    {
> > > >    	__notify_execute_cb(rq, irq_work_imm);
> > > >    }
> > > > @@ -268,37 +268,6 @@ i915_request_active_engine(struct i915_request *rq,
> > > >    	return ret;
> > > >    }
> > > > -
> > > > -static void remove_from_engine(struct i915_request *rq)
> > > > -{
> > > > -	struct intel_engine_cs *engine, *locked;
> > > > -
> > > > -	/*
> > > > -	 * Virtual engines complicate acquiring the engine timeline lock,
> > > > -	 * as their rq->engine pointer is not stable until under that
> > > > -	 * engine lock. The simple ploy we use is to take the lock then
> > > > -	 * check that the rq still belongs to the newly locked engine.
> > > > -	 */
> > > > -	locked = READ_ONCE(rq->engine);
> > > > -	spin_lock_irq(&locked->sched_engine->lock);
> > > > -	while (unlikely(locked != (engine = READ_ONCE(rq->engine)))) {
> > > > -		spin_unlock(&locked->sched_engine->lock);
> > > > -		spin_lock(&engine->sched_engine->lock);
> > > > -		locked = engine;
> > > > -	}
> > > > -	list_del_init(&rq->sched.link);
> > > > -
> > > > -	clear_bit(I915_FENCE_FLAG_PQUEUE, &rq->fence.flags);
> > > > -	clear_bit(I915_FENCE_FLAG_HOLD, &rq->fence.flags);
> > > > -
> > > > -	/* Prevent further __await_execution() registering a cb, then flush */
> > > > -	set_bit(I915_FENCE_FLAG_ACTIVE, &rq->fence.flags);
> > > > -
> > > > -	spin_unlock_irq(&locked->sched_engine->lock);
> > > > -
> > > > -	__notify_execute_cb_imm(rq);
> > > > -}
> > > > -
> > > >    static void __rq_init_watchdog(struct i915_request *rq)
> > > >    {
> > > >    	rq->watchdog.timer.function = NULL;
> > > > @@ -395,9 +364,7 @@ bool i915_request_retire(struct i915_request *rq)
> > > >    	 * after removing the breadcrumb and signaling it, so that we do not
> > > >    	 * inadvertently attach the breadcrumb to a completed request.
> > > >    	 */
> > > > -	if (!list_empty(&rq->sched.link))
> > > > -		remove_from_engine(rq);
> > > > -	atomic_dec(&rq->context->guc_id_ref);
> > > > +	rq->engine->remove_active_request(rq);
> > > >    	GEM_BUG_ON(!llist_empty(&rq->execute_cb));
> > > >    	__list_del_entry(&rq->link); /* poison neither prev/next (RCU walks) */
> > > > @@ -539,7 +506,7 @@ __await_execution(struct i915_request *rq,
> > > >    	if (llist_add(&cb->work.node.llist, &signal->execute_cb)) {
> > > >    		if (i915_request_is_active(signal) ||
> > > >    		    __request_in_flight(signal))
> > > > -			__notify_execute_cb_imm(signal);
> > > > +			i915_request_notify_execute_cb_imm(signal);
> > > >    	}
> > > >    	return 0;
> > > > @@ -676,7 +643,7 @@ bool __i915_request_submit(struct i915_request *request)
> > > >    	result = true;
> > > >    	GEM_BUG_ON(test_bit(I915_FENCE_FLAG_ACTIVE, &request->fence.flags));
> > > > -	list_move_tail(&request->sched.link, &engine->sched_engine->requests);
> > > > +	engine->add_active_request(request);
> > > >    active:
> > > >    	clear_bit(I915_FENCE_FLAG_PQUEUE, &request->fence.flags);
> > > >    	set_bit(I915_FENCE_FLAG_ACTIVE, &request->fence.flags);
> > > > diff --git a/drivers/gpu/drm/i915/i915_request.h b/drivers/gpu/drm/i915/i915_request.h
> > > > index f870cd75a001..bcc6340c505e 100644
> > > > --- a/drivers/gpu/drm/i915/i915_request.h
> > > > +++ b/drivers/gpu/drm/i915/i915_request.h
> > > > @@ -649,4 +649,6 @@ bool
> > > >    i915_request_active_engine(struct i915_request *rq,
> > > >    			   struct intel_engine_cs **active);
> > > > +void i915_request_notify_execute_cb_imm(struct i915_request *rq);
> > > > +
> > > >    #endif /* I915_REQUEST_H */
> > > >

Patch

diff --git a/drivers/gpu/drm/i915/gt/intel_context.c b/drivers/gpu/drm/i915/gt/intel_context.c
index b24a1b7a3f88..2f01437056a8 100644
--- a/drivers/gpu/drm/i915/gt/intel_context.c
+++ b/drivers/gpu/drm/i915/gt/intel_context.c
@@ -392,6 +392,9 @@  intel_context_init(struct intel_context *ce, struct intel_engine_cs *engine)
 	spin_lock_init(&ce->guc_state.lock);
 	INIT_LIST_HEAD(&ce->guc_state.fences);
 
+	spin_lock_init(&ce->guc_active.lock);
+	INIT_LIST_HEAD(&ce->guc_active.requests);
+
 	ce->guc_id = GUC_INVALID_LRC_ID;
 	INIT_LIST_HEAD(&ce->guc_id_link);
 
diff --git a/drivers/gpu/drm/i915/gt/intel_context_types.h b/drivers/gpu/drm/i915/gt/intel_context_types.h
index 6945963a31ba..b63c8cf7823b 100644
--- a/drivers/gpu/drm/i915/gt/intel_context_types.h
+++ b/drivers/gpu/drm/i915/gt/intel_context_types.h
@@ -165,6 +165,13 @@  struct intel_context {
 		struct list_head fences;
 	} guc_state;
 
+	struct {
+		/** lock: protects everything in guc_active */
+		spinlock_t lock;
+		/** requests: active requests on this context */
+		struct list_head requests;
+	} guc_active;
+
 	/* GuC scheduling state that does not require a lock. */
 	atomic_t guc_sched_state_no_lock;
 
diff --git a/drivers/gpu/drm/i915/gt/intel_engine_types.h b/drivers/gpu/drm/i915/gt/intel_engine_types.h
index e7cb6a06db9d..f9d264c008e8 100644
--- a/drivers/gpu/drm/i915/gt/intel_engine_types.h
+++ b/drivers/gpu/drm/i915/gt/intel_engine_types.h
@@ -426,6 +426,12 @@  struct intel_engine_cs {
 
 	void		(*release)(struct intel_engine_cs *engine);
 
+	/*
+	 * Add / remove request from engine active tracking
+	 */
+	void		(*add_active_request)(struct i915_request *rq);
+	void		(*remove_active_request)(struct i915_request *rq);
+
 	struct intel_engine_execlists execlists;
 
 	/*
diff --git a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
index c10ea6080752..c301a2d088b1 100644
--- a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
+++ b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
@@ -3118,6 +3118,42 @@  static void execlists_park(struct intel_engine_cs *engine)
 	cancel_timer(&engine->execlists.preempt);
 }
 
+static void add_to_engine(struct i915_request *rq)
+{
+	lockdep_assert_held(&rq->engine->sched_engine->lock);
+	list_move_tail(&rq->sched.link, &rq->engine->sched_engine->requests);
+}
+
+static void remove_from_engine(struct i915_request *rq)
+{
+	struct intel_engine_cs *engine, *locked;
+
+	/*
+	 * Virtual engines complicate acquiring the engine timeline lock,
+	 * as their rq->engine pointer is not stable until under that
+	 * engine lock. The simple ploy we use is to take the lock then
+	 * check that the rq still belongs to the newly locked engine.
+	 */
+	locked = READ_ONCE(rq->engine);
+	spin_lock_irq(&locked->sched_engine->lock);
+	while (unlikely(locked != (engine = READ_ONCE(rq->engine)))) {
+		spin_unlock(&locked->sched_engine->lock);
+		spin_lock(&engine->sched_engine->lock);
+		locked = engine;
+	}
+	list_del_init(&rq->sched.link);
+
+	clear_bit(I915_FENCE_FLAG_PQUEUE, &rq->fence.flags);
+	clear_bit(I915_FENCE_FLAG_HOLD, &rq->fence.flags);
+
+	/* Prevent further __await_execution() registering a cb, then flush */
+	set_bit(I915_FENCE_FLAG_ACTIVE, &rq->fence.flags);
+
+	spin_unlock_irq(&locked->sched_engine->lock);
+
+	i915_request_notify_execute_cb_imm(rq);
+}
+
 static bool can_preempt(struct intel_engine_cs *engine)
 {
 	if (GRAPHICS_VER(engine->i915) > 8)
@@ -3218,6 +3254,8 @@  logical_ring_default_vfuncs(struct intel_engine_cs *engine)
 	engine->cops = &execlists_context_ops;
 	engine->request_alloc = execlists_request_alloc;
 	engine->bump_serial = execlist_bump_serial;
+	engine->add_active_request = add_to_engine;
+	engine->remove_active_request = remove_from_engine;
 
 	engine->reset.prepare = execlists_reset_prepare;
 	engine->reset.rewind = execlists_reset_rewind;
@@ -3912,6 +3950,8 @@  execlists_create_virtual(struct intel_engine_cs **siblings, unsigned int count)
 			 "v%dx%d", ve->base.class, count);
 		ve->base.context_size = sibling->context_size;
 
+		ve->base.add_active_request = sibling->add_active_request;
+		ve->base.remove_active_request = sibling->remove_active_request;
 		ve->base.emit_bb_start = sibling->emit_bb_start;
 		ve->base.emit_flush = sibling->emit_flush;
 		ve->base.emit_init_breadcrumb = sibling->emit_init_breadcrumb;
diff --git a/drivers/gpu/drm/i915/gt/intel_gt_pm.c b/drivers/gpu/drm/i915/gt/intel_gt_pm.c
index aef3084e8b16..463a6ae605a0 100644
--- a/drivers/gpu/drm/i915/gt/intel_gt_pm.c
+++ b/drivers/gpu/drm/i915/gt/intel_gt_pm.c
@@ -174,8 +174,6 @@  static void gt_sanitize(struct intel_gt *gt, bool force)
 	if (intel_gt_is_wedged(gt))
 		intel_gt_unset_wedged(gt);
 
-	intel_uc_sanitize(&gt->uc);
-
 	for_each_engine(engine, gt, id)
 		if (engine->reset.prepare)
 			engine->reset.prepare(engine);
@@ -191,6 +189,8 @@  static void gt_sanitize(struct intel_gt *gt, bool force)
 			__intel_engine_reset(engine, false);
 	}
 
+	intel_uc_reset(&gt->uc, false);
+
 	for_each_engine(engine, gt, id)
 		if (engine->reset.finish)
 			engine->reset.finish(engine);
@@ -243,6 +243,8 @@  int intel_gt_resume(struct intel_gt *gt)
 		goto err_wedged;
 	}
 
+	intel_uc_reset_finish(&gt->uc);
+
 	intel_rps_enable(&gt->rps);
 	intel_llc_enable(&gt->llc);
 
diff --git a/drivers/gpu/drm/i915/gt/intel_reset.c b/drivers/gpu/drm/i915/gt/intel_reset.c
index 72251638d4ea..2987282dff6d 100644
--- a/drivers/gpu/drm/i915/gt/intel_reset.c
+++ b/drivers/gpu/drm/i915/gt/intel_reset.c
@@ -826,6 +826,8 @@  static int gt_reset(struct intel_gt *gt, intel_engine_mask_t stalled_mask)
 		__intel_engine_reset(engine, stalled_mask & engine->mask);
 	local_bh_enable();
 
+	intel_uc_reset(&gt->uc, true);
+
 	intel_ggtt_restore_fences(gt->ggtt);
 
 	return err;
@@ -850,6 +852,8 @@  static void reset_finish(struct intel_gt *gt, intel_engine_mask_t awake)
 		if (awake & engine->mask)
 			intel_engine_pm_put(engine);
 	}
+
+	intel_uc_reset_finish(&gt->uc);
 }
 
 static void nop_submit_request(struct i915_request *request)
@@ -903,6 +907,7 @@  static void __intel_gt_set_wedged(struct intel_gt *gt)
 	for_each_engine(engine, gt, id)
 		if (engine->reset.cancel)
 			engine->reset.cancel(engine);
+	intel_uc_cancel_requests(&gt->uc);
 	local_bh_enable();
 
 	reset_finish(gt, awake);
@@ -1191,6 +1196,9 @@  int __intel_engine_reset_bh(struct intel_engine_cs *engine, const char *msg)
 	ENGINE_TRACE(engine, "flags=%lx\n", gt->reset.flags);
 	GEM_BUG_ON(!test_bit(I915_RESET_ENGINE + engine->id, &gt->reset.flags));
 
+	if (intel_engine_uses_guc(engine))
+		return -ENODEV;
+
 	if (!intel_engine_pm_get_if_awake(engine))
 		return 0;
 
@@ -1201,13 +1209,10 @@  int __intel_engine_reset_bh(struct intel_engine_cs *engine, const char *msg)
 			   "Resetting %s for %s\n", engine->name, msg);
 	atomic_inc(&engine->i915->gpu_error.reset_engine_count[engine->uabi_class]);
 
-	if (intel_engine_uses_guc(engine))
-		ret = intel_guc_reset_engine(&engine->gt->uc.guc, engine);
-	else
-		ret = intel_gt_reset_engine(engine);
+	ret = intel_gt_reset_engine(engine);
 	if (ret) {
 		/* If we fail here, we expect to fallback to a global reset */
-		ENGINE_TRACE(engine, "Failed to reset, err: %d\n", ret);
+		ENGINE_TRACE(engine, "Failed to reset %s, err: %d\n", engine->name, ret);
 		goto out;
 	}
 
@@ -1341,7 +1346,8 @@  void intel_gt_handle_error(struct intel_gt *gt,
 	 * Try engine reset when available. We fall back to full reset if
 	 * single reset fails.
 	 */
-	if (intel_has_reset_engine(gt) && !intel_gt_is_wedged(gt)) {
+	if (!intel_uc_uses_guc_submission(&gt->uc) &&
+	    intel_has_reset_engine(gt) && !intel_gt_is_wedged(gt)) {
 		local_bh_disable();
 		for_each_engine_masked(engine, gt, engine_mask, tmp) {
 			BUILD_BUG_ON(I915_RESET_MODESET >= I915_RESET_ENGINE);
diff --git a/drivers/gpu/drm/i915/gt/intel_ring_submission.c b/drivers/gpu/drm/i915/gt/intel_ring_submission.c
index e1506b280df1..99dcdc8fba12 100644
--- a/drivers/gpu/drm/i915/gt/intel_ring_submission.c
+++ b/drivers/gpu/drm/i915/gt/intel_ring_submission.c
@@ -1049,6 +1049,25 @@  static void ring_bump_serial(struct intel_engine_cs *engine)
 	engine->serial++;
 }
 
+static void add_to_engine(struct i915_request *rq)
+{
+	lockdep_assert_held(&rq->engine->sched_engine->lock);
+	list_move_tail(&rq->sched.link, &rq->engine->sched_engine->requests);
+}
+
+static void remove_from_engine(struct i915_request *rq)
+{
+	spin_lock_irq(&rq->engine->sched_engine->lock);
+	list_del_init(&rq->sched.link);
+
+	/* Prevent further __await_execution() registering a cb, then flush */
+	set_bit(I915_FENCE_FLAG_ACTIVE, &rq->fence.flags);
+
+	spin_unlock_irq(&rq->engine->sched_engine->lock);
+
+	i915_request_notify_execute_cb_imm(rq);
+}
+
 static void setup_common(struct intel_engine_cs *engine)
 {
 	struct drm_i915_private *i915 = engine->i915;
@@ -1066,6 +1085,9 @@  static void setup_common(struct intel_engine_cs *engine)
 	engine->reset.cancel = reset_cancel;
 	engine->reset.finish = reset_finish;
 
+	engine->add_active_request = add_to_engine;
+	engine->remove_active_request = remove_from_engine;
+
 	engine->cops = &ring_context_ops;
 	engine->request_alloc = ring_request_alloc;
 	engine->bump_serial = ring_bump_serial;
diff --git a/drivers/gpu/drm/i915/gt/mock_engine.c b/drivers/gpu/drm/i915/gt/mock_engine.c
index fc5a65ab1937..c12ff3a75ce6 100644
--- a/drivers/gpu/drm/i915/gt/mock_engine.c
+++ b/drivers/gpu/drm/i915/gt/mock_engine.c
@@ -235,6 +235,35 @@  static void mock_submit_request(struct i915_request *request)
 	spin_unlock_irqrestore(&engine->hw_lock, flags);
 }
 
+static void mock_add_to_engine(struct i915_request *rq)
+{
+	lockdep_assert_held(&rq->engine->sched_engine->lock);
+	list_move_tail(&rq->sched.link, &rq->engine->sched_engine->requests);
+}
+
+static void mock_remove_from_engine(struct i915_request *rq)
+{
+	struct intel_engine_cs *engine, *locked;
+
+	/*
+	 * Virtual engines complicate acquiring the engine timeline lock,
+	 * as their rq->engine pointer is not stable until under that
+	 * engine lock. The simple ploy we use is to take the lock then
+	 * check that the rq still belongs to the newly locked engine.
+	 */
+
+	locked = READ_ONCE(rq->engine);
+	spin_lock_irq(&locked->sched_engine->lock);
+	while (unlikely(locked != (engine = READ_ONCE(rq->engine)))) {
+		spin_unlock(&locked->sched_engine->lock);
+		spin_lock(&engine->sched_engine->lock);
+		locked = engine;
+	}
+	list_del_init(&rq->sched.link);
+	spin_unlock_irq(&locked->sched_engine->lock);
+}
+
+
 static void mock_reset_prepare(struct intel_engine_cs *engine)
 {
 }
@@ -327,6 +356,8 @@  struct intel_engine_cs *mock_engine(struct drm_i915_private *i915,
 	engine->base.emit_flush = mock_emit_flush;
 	engine->base.emit_fini_breadcrumb = mock_emit_breadcrumb;
 	engine->base.submit_request = mock_submit_request;
+	engine->base.add_active_request = mock_add_to_engine;
+	engine->base.remove_active_request = mock_remove_from_engine;
 
 	engine->base.reset.prepare = mock_reset_prepare;
 	engine->base.reset.rewind = mock_reset_rewind;
diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc.c b/drivers/gpu/drm/i915/gt/uc/intel_guc.c
index 6661dcb02239..9b09395b998f 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc.c
@@ -572,19 +572,6 @@  int intel_guc_suspend(struct intel_guc *guc)
 	return 0;
 }
 
-/**
- * intel_guc_reset_engine() - ask GuC to reset an engine
- * @guc:	intel_guc structure
- * @engine:	engine to be reset
- */
-int intel_guc_reset_engine(struct intel_guc *guc,
-			   struct intel_engine_cs *engine)
-{
-	/* XXX: to be implemented with submission interface rework */
-
-	return -ENODEV;
-}
-
 /**
  * intel_guc_resume() - notify GuC resuming from suspend state
  * @guc:	the guc
diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc.h b/drivers/gpu/drm/i915/gt/uc/intel_guc.h
index 22eb1e9cca41..40c9868762d7 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc.h
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc.h
@@ -242,14 +242,16 @@  static inline void intel_guc_disable_msg(struct intel_guc *guc, u32 mask)
 
 int intel_guc_wait_for_idle(struct intel_guc *guc, long timeout);
 
-int intel_guc_reset_engine(struct intel_guc *guc,
-			   struct intel_engine_cs *engine);
-
 int intel_guc_deregister_done_process_msg(struct intel_guc *guc,
 					  const u32 *msg, u32 len);
 int intel_guc_sched_done_process_msg(struct intel_guc *guc,
 				     const u32 *msg, u32 len);
 
+void intel_guc_submission_reset_prepare(struct intel_guc *guc);
+void intel_guc_submission_reset(struct intel_guc *guc, bool stalled);
+void intel_guc_submission_reset_finish(struct intel_guc *guc);
+void intel_guc_submission_cancel_requests(struct intel_guc *guc);
+
 void intel_guc_load_status(struct intel_guc *guc, struct drm_printer *p);
 
 #endif
diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
index 83058df5ba01..b8c894ad8caf 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
@@ -141,7 +141,7 @@  context_wait_for_deregister_to_register(struct intel_context *ce)
 static inline void
 set_context_wait_for_deregister_to_register(struct intel_context *ce)
 {
-	/* Only should be called from guc_lrc_desc_pin() */
+	/* Only should be called from guc_lrc_desc_pin() without lock */
 	ce->guc_state.sched_state |=
 		SCHED_STATE_WAIT_FOR_DEREGISTER_TO_REGISTER;
 }
@@ -241,15 +241,31 @@  static int guc_lrc_desc_pool_create(struct intel_guc *guc)
 
 static void guc_lrc_desc_pool_destroy(struct intel_guc *guc)
 {
+	guc->lrc_desc_pool_vaddr = NULL;
 	i915_vma_unpin_and_release(&guc->lrc_desc_pool, I915_VMA_RELEASE_MAP);
 }
 
+static inline bool guc_submission_initialized(struct intel_guc *guc)
+{
+	return guc->lrc_desc_pool_vaddr != NULL;
+}
+
 static inline void reset_lrc_desc(struct intel_guc *guc, u32 id)
 {
-	struct guc_lrc_desc *desc = __get_lrc_desc(guc, id);
+	if (likely(guc_submission_initialized(guc))) {
+		struct guc_lrc_desc *desc = __get_lrc_desc(guc, id);
+		unsigned long flags;
 
-	memset(desc, 0, sizeof(*desc));
-	xa_erase_irq(&guc->context_lookup, id);
+		memset(desc, 0, sizeof(*desc));
+
+		/*
+		 * xarray API doesn't have xa_erase_irqsave wrapper, so calling
+		 * the lower level functions directly.
+		 */
+		xa_lock_irqsave(&guc->context_lookup, flags);
+		__xa_erase(&guc->context_lookup, id);
+		xa_unlock_irqrestore(&guc->context_lookup, flags);
+	}
 }
 
 static inline bool lrc_desc_registered(struct intel_guc *guc, u32 id)
@@ -260,7 +276,15 @@  static inline bool lrc_desc_registered(struct intel_guc *guc, u32 id)
 static inline void set_lrc_desc_registered(struct intel_guc *guc, u32 id,
 					   struct intel_context *ce)
 {
-	xa_store_irq(&guc->context_lookup, id, ce, GFP_ATOMIC);
+	unsigned long flags;
+
+	/*
+	 * xarray API doesn't have xa_save_irqsave wrapper, so calling the
+	 * lower level functions directly.
+	 */
+	xa_lock_irqsave(&guc->context_lookup, flags);
+	__xa_store(&guc->context_lookup, id, ce, GFP_ATOMIC);
+	xa_unlock_irqrestore(&guc->context_lookup, flags);
 }
 
 static int guc_submission_busy_loop(struct intel_guc* guc,
@@ -331,6 +355,8 @@  int intel_guc_wait_for_idle(struct intel_guc *guc, long timeout)
 					interruptible, timeout);
 }
 
+static int guc_lrc_desc_pin(struct intel_context *ce, bool loop);
+
 static int guc_add_request(struct intel_guc *guc, struct i915_request *rq)
 {
 	int err;
@@ -338,11 +364,22 @@  static int guc_add_request(struct intel_guc *guc, struct i915_request *rq)
 	u32 action[3];
 	int len = 0;
 	u32 g2h_len_dw = 0;
-	bool enabled = context_enabled(ce);
+	bool enabled;
 
 	GEM_BUG_ON(!atomic_read(&ce->guc_id_ref));
 	GEM_BUG_ON(context_guc_id_invalid(ce));
 
+	/*
+	 * Corner case where the GuC firmware was blown away and reloaded while
+	 * this context was pinned.
+	 */
+	if (unlikely(!lrc_desc_registered(guc, ce->guc_id))) {
+		err = guc_lrc_desc_pin(ce, false);
+		if (unlikely(err))
+			goto out;
+	}
+	enabled = context_enabled(ce);
+
 	if (!enabled) {
 		action[len++] = INTEL_GUC_ACTION_SCHED_CONTEXT_MODE_SET;
 		action[len++] = ce->guc_id;
@@ -365,6 +402,7 @@  static int guc_add_request(struct intel_guc *guc, struct i915_request *rq)
 		intel_context_put(ce);
 	}
 
+out:
 	return err;
 }
 
@@ -419,15 +457,10 @@  static int guc_dequeue_one_context(struct intel_guc *guc)
 	if (submit) {
 		guc_set_lrc_tail(last);
 resubmit:
-		/*
-		 * We only check for -EBUSY here even though it is possible for
-		 * -EDEADLK to be returned. If -EDEADLK is returned, the GuC has
-		 * died and a full GPU needs to be done. The hangcheck will
-		 * eventually detect that the GuC has died and trigger this
-		 * reset so no need to handle -EDEADLK here.
-		 */
 		ret = guc_add_request(guc, last);
-		if (ret == -EBUSY) {
+		if (unlikely(ret == -EIO))
+			goto deadlk;
+		else if (ret == -EBUSY) {
 			tasklet_schedule(&sched_engine->tasklet);
 			guc->stalled_request = last;
 			return false;
@@ -437,6 +470,11 @@  static int guc_dequeue_one_context(struct intel_guc *guc)
 
 	guc->stalled_request = NULL;
 	return submit;
+
+deadlk:
+	sched_engine->tasklet.callback = NULL;
+	tasklet_disable_nosync(&sched_engine->tasklet);
+	return false;
 }
 
 static void guc_submission_tasklet(struct tasklet_struct *t)
@@ -463,27 +501,165 @@  static void cs_irq_handler(struct intel_engine_cs *engine, u16 iir)
 		intel_engine_signal_breadcrumbs(engine);
 }
 
-static void guc_reset_prepare(struct intel_engine_cs *engine)
+static void __guc_context_destroy(struct intel_context *ce);
+static void release_guc_id(struct intel_guc *guc, struct intel_context *ce);
+static void guc_signal_context_fence(struct intel_context *ce);
+
+static void scrub_guc_desc_for_outstanding_g2h(struct intel_guc *guc)
+{
+	struct intel_context *ce;
+	unsigned long index, flags;
+	bool pending_disable, pending_enable, deregister, destroyed;
+
+	xa_for_each(&guc->context_lookup, index, ce) {
+		/* Flush context */
+		spin_lock_irqsave(&ce->guc_state.lock, flags);
+		spin_unlock_irqrestore(&ce->guc_state.lock, flags);
+
+		/*
+		 * Once we are at this point submission_disabled() is guaranteed
+		 * to visible to all callers who set the below flags (see above
+		 * flush and flushes in reset_prepare). If submission_disabled()
+		 * is set, the caller shouldn't set these flags.
+		 */
+
+		destroyed = context_destroyed(ce);
+		pending_enable = context_pending_enable(ce);
+		pending_disable = context_pending_disable(ce);
+		deregister = context_wait_for_deregister_to_register(ce);
+		init_sched_state(ce);
+
+		if (pending_enable || destroyed || deregister) {
+			atomic_dec(&guc->outstanding_submission_g2h);
+			if (deregister)
+				guc_signal_context_fence(ce);
+			if (destroyed) {
+				release_guc_id(guc, ce);
+				__guc_context_destroy(ce);
+			}
+			if (pending_enable|| deregister)
+				intel_context_put(ce);
+		}
+
+		/* Not mutualy exclusive with above if statement. */
+		if (pending_disable) {
+			guc_signal_context_fence(ce);
+			intel_context_sched_disable_unpin(ce);
+			atomic_dec(&guc->outstanding_submission_g2h);
+			intel_context_put(ce);
+		}
+	}
+}
+
+static inline bool
+submission_disabled(struct intel_guc *guc)
+{
+	struct i915_sched_engine * const sched_engine = guc->sched_engine;
+
+	return unlikely(!__tasklet_is_enabled(&sched_engine->tasklet));
+}
+
+static void disable_submission(struct intel_guc *guc)
+{
+	struct i915_sched_engine * const sched_engine = guc->sched_engine;
+
+	if (__tasklet_is_enabled(&sched_engine->tasklet)) {
+		GEM_BUG_ON(!guc->ct.enabled);
+		__tasklet_disable_sync_once(&sched_engine->tasklet);
+		sched_engine->tasklet.callback = NULL;
+	}
+}
+
+static void enable_submission(struct intel_guc *guc)
+{
+	struct i915_sched_engine * const sched_engine = guc->sched_engine;
+	unsigned long flags;
+
+	spin_lock_irqsave(&guc->sched_engine->lock, flags);
+	sched_engine->tasklet.callback = guc_submission_tasklet;
+	wmb();
+	if (!__tasklet_is_enabled(&sched_engine->tasklet) &&
+	    __tasklet_enable(&sched_engine->tasklet)) {
+		GEM_BUG_ON(!guc->ct.enabled);
+
+		/* And kick in case we missed a new request submission. */
+		tasklet_hi_schedule(&sched_engine->tasklet);
+	}
+	spin_unlock_irqrestore(&guc->sched_engine->lock, flags);
+}
+
+static void guc_flush_submissions(struct intel_guc *guc)
 {
-	ENGINE_TRACE(engine, "\n");
+	struct i915_sched_engine * const sched_engine = guc->sched_engine;
+	unsigned long flags;
+
+	spin_lock_irqsave(&sched_engine->lock, flags);
+	spin_unlock_irqrestore(&sched_engine->lock, flags);
+}
+
+void intel_guc_submission_reset_prepare(struct intel_guc *guc)
+{
+	int i;
+
+	if (unlikely(!guc_submission_initialized(guc)))
+		/* Reset called during driver load? GuC not yet initialised! */
+		return;
+
+	disable_submission(guc);
+	guc->interrupts.disable(guc);
+
+	/* Flush IRQ handler */
+	spin_lock_irq(&guc_to_gt(guc)->irq_lock);
+	spin_unlock_irq(&guc_to_gt(guc)->irq_lock);
+
+	guc_flush_submissions(guc);
 
 	/*
-	 * Prevent request submission to the hardware until we have
-	 * completed the reset in i915_gem_reset_finish(). If a request
-	 * is completed by one engine, it may then queue a request
-	 * to a second via its execlists->tasklet *just* as we are
-	 * calling engine->init_hw() and also writing the ELSP.
-	 * Turning off the execlists->tasklet until the reset is over
-	 * prevents the race.
-	 */
-	__tasklet_disable_sync_once(&engine->sched_engine->tasklet);
+	 * Handle any outstanding G2Hs before reset. Call IRQ handler directly
+	 * each pass as interrupt have been disabled. We always scrub for
+	 * outstanding G2H as it is possible for outstanding_submission_g2h to
+	 * be incremented after the context state update.
+ 	 */
+	for (i = 0; i < 4 && atomic_read(&guc->outstanding_submission_g2h); ++i) {
+		intel_guc_to_host_event_handler(guc);
+#define wait_for_reset(guc, wait_var) \
+		guc_wait_for_pending_msg(guc, wait_var, false, (HZ / 20))
+		do {
+			wait_for_reset(guc, &guc->outstanding_submission_g2h);
+		} while (!list_empty(&guc->ct.requests.incoming));
+	}
+	scrub_guc_desc_for_outstanding_g2h(guc);
 }
 
-static void guc_reset_state(struct intel_context *ce,
-			    struct intel_engine_cs *engine,
-			    u32 head,
-			    bool scrub)
+static struct intel_engine_cs *
+guc_virtual_get_sibling(struct intel_engine_cs *ve, unsigned int sibling)
 {
+	struct intel_engine_cs *engine;
+	intel_engine_mask_t tmp, mask = ve->mask;
+	unsigned int num_siblings = 0;
+
+	for_each_engine_masked(engine, ve->gt, mask, tmp)
+		if (num_siblings++ == sibling)
+			return engine;
+
+	return NULL;
+}
+
+static inline struct intel_engine_cs *
+__context_to_physical_engine(struct intel_context *ce)
+{
+	struct intel_engine_cs *engine = ce->engine;
+
+	if (intel_engine_is_virtual(engine))
+		engine = guc_virtual_get_sibling(engine, 0);
+
+	return engine;
+}
+
+static void guc_reset_state(struct intel_context *ce, u32 head, bool scrub)
+{
+	struct intel_engine_cs *engine = __context_to_physical_engine(ce);
+
 	GEM_BUG_ON(!intel_context_is_pinned(ce));
 
 	/*
@@ -501,42 +677,147 @@  static void guc_reset_state(struct intel_context *ce,
 	lrc_update_regs(ce, engine, head);
 }
 
-static void guc_reset_rewind(struct intel_engine_cs *engine, bool stalled)
+static void guc_reset_nop(struct intel_engine_cs *engine)
 {
-	struct intel_engine_execlists * const execlists = &engine->execlists;
-	struct i915_request *rq;
+}
+
+static void guc_rewind_nop(struct intel_engine_cs *engine, bool stalled)
+{
+}
+
+static void
+__unwind_incomplete_requests(struct intel_context *ce)
+{
+	struct i915_request *rq, *rn;
+	struct list_head *pl;
+	int prio = I915_PRIORITY_INVALID;
+	struct i915_sched_engine * const sched_engine =
+		ce->engine->sched_engine;
 	unsigned long flags;
 
-	spin_lock_irqsave(&engine->sched_engine->lock, flags);
+	spin_lock_irqsave(&sched_engine->lock, flags);
+	spin_lock(&ce->guc_active.lock);
+	list_for_each_entry_safe(rq, rn,
+				 &ce->guc_active.requests,
+				 sched.link) {
+		if (i915_request_completed(rq))
+			continue;
+
+		list_del_init(&rq->sched.link);
+		spin_unlock(&ce->guc_active.lock);
+
+		__i915_request_unsubmit(rq);
+
+		/* Push the request back into the queue for later resubmission. */
+		GEM_BUG_ON(rq_prio(rq) == I915_PRIORITY_INVALID);
+		if (rq_prio(rq) != prio) {
+			prio = rq_prio(rq);
+			pl = i915_sched_lookup_priolist(sched_engine, prio);
+		}
+		GEM_BUG_ON(i915_sched_engine_is_empty(sched_engine));
+
+		list_add_tail(&rq->sched.link, pl);
+		set_bit(I915_FENCE_FLAG_PQUEUE, &rq->fence.flags);
 
-	/* Push back any incomplete requests for replay after the reset. */
-	rq = execlists_unwind_incomplete_requests(execlists);
-	if (!rq)
-		goto out_unlock;
+		spin_lock(&ce->guc_active.lock);
+	}
+	spin_unlock(&ce->guc_active.lock);
+	spin_unlock_irqrestore(&sched_engine->lock, flags);
+}
+
+static struct i915_request *context_find_active_request(struct intel_context *ce)
+{
+	struct i915_request *rq, *active = NULL;
+	unsigned long flags;
+
+	spin_lock_irqsave(&ce->guc_active.lock, flags);
+	list_for_each_entry_reverse(rq, &ce->guc_active.requests,
+				    sched.link) {
+		if (i915_request_completed(rq))
+			break;
+
+		active = rq;
+	}
+	spin_unlock_irqrestore(&ce->guc_active.lock, flags);
+
+	return active;
+}
+
+static void __guc_reset_context(struct intel_context *ce, bool stalled)
+{
+	struct i915_request *rq;
+	u32 head;
+
+	/*
+	 * GuC will implicitly mark the context as non-schedulable
+	 * when it sends the reset notification. Make sure our state
+	 * reflects this change. The context will be marked enabled
+	 * on resubmission.
+	 */
+	clr_context_enabled(ce);
+
+	rq = context_find_active_request(ce);
+	if (!rq) {
+		head = ce->ring->tail;
+		stalled = false;
+		goto out_replay;
+	}
 
 	if (!i915_request_started(rq))
 		stalled = false;
 
+	GEM_BUG_ON(i915_active_is_idle(&ce->active));
+	head = intel_ring_wrap(ce->ring, rq->head);
 	__i915_request_reset(rq, stalled);
-	guc_reset_state(rq->context, engine, rq->head, stalled);
 
-out_unlock:
-	spin_unlock_irqrestore(&engine->sched_engine->lock, flags);
+out_replay:
+	guc_reset_state(ce, head, stalled);
+	__unwind_incomplete_requests(ce);
 }
 
-static void guc_reset_cancel(struct intel_engine_cs *engine)
+void intel_guc_submission_reset(struct intel_guc *guc, bool stalled)
+{
+	struct intel_context *ce;
+	unsigned long index;
+
+	if (unlikely(!guc_submission_initialized(guc)))
+		/* Reset called during driver load? GuC not yet initialised! */
+		return;
+
+	xa_for_each(&guc->context_lookup, index, ce)
+		if (intel_context_is_pinned(ce))
+			__guc_reset_context(ce, stalled);
+
+	/* GuC is blown away, drop all references to contexts */
+	xa_destroy(&guc->context_lookup);
+}
+
+static void guc_cancel_context_requests(struct intel_context *ce)
+{
+	struct i915_sched_engine *sched_engine = ce_to_guc(ce)->sched_engine;
+	struct i915_request *rq;
+	unsigned long flags;
+
+	/* Mark all executing requests as skipped. */
+	spin_lock_irqsave(&sched_engine->lock, flags);
+	spin_lock(&ce->guc_active.lock);
+	list_for_each_entry(rq, &ce->guc_active.requests, sched.link)
+		i915_request_put(i915_request_mark_eio(rq));
+	spin_unlock(&ce->guc_active.lock);
+	spin_unlock_irqrestore(&sched_engine->lock, flags);
+}
+
+static void
+guc_cancel_sched_engine_requests(struct i915_sched_engine *sched_engine)
 {
-	struct i915_sched_engine * const sched_engine = engine->sched_engine;
 	struct i915_request *rq, *rn;
 	struct rb_node *rb;
 	unsigned long flags;
 
 	/* Can be called during boot if GuC fails to load */
-	if (!engine->gt)
+	if (!sched_engine)
 		return;
 
-	ENGINE_TRACE(engine, "\n");
-
 	/*
 	 * Before we call engine->cancel_requests(), we should have exclusive
 	 * access to the submission state. This is arranged for us by the
@@ -553,21 +834,16 @@  static void guc_reset_cancel(struct intel_engine_cs *engine)
 	 */
 	spin_lock_irqsave(&sched_engine->lock, flags);
 
-	/* Mark all executing requests as skipped. */
-	list_for_each_entry(rq, &sched_engine->requests, sched.link) {
-		i915_request_set_error_once(rq, -EIO);
-		i915_request_mark_complete(rq);
-	}
-
 	/* Flush the queued requests to the timeline list (for retiring). */
 	while ((rb = rb_first_cached(&sched_engine->queue))) {
 		struct i915_priolist *p = to_priolist(rb);
 
 		priolist_for_each_request_consume(rq, rn, p) {
 			list_del_init(&rq->sched.link);
+
 			__i915_request_submit(rq);
-			dma_fence_set_error(&rq->fence, -EIO);
-			i915_request_mark_complete(rq);
+
+			i915_request_put(i915_request_mark_eio(rq));
 		}
 
 		rb_erase_cached(&p->node, &sched_engine->queue);
@@ -582,14 +858,38 @@  static void guc_reset_cancel(struct intel_engine_cs *engine)
 	spin_unlock_irqrestore(&sched_engine->lock, flags);
 }
 
-static void guc_reset_finish(struct intel_engine_cs *engine)
+void intel_guc_submission_cancel_requests(struct intel_guc *guc)
 {
-	if (__tasklet_enable(&engine->sched_engine->tasklet))
-		/* And kick in case we missed a new request submission. */
-		tasklet_hi_schedule(&engine->sched_engine->tasklet);
+	struct intel_context *ce;
+	unsigned long index;
+
+	xa_for_each(&guc->context_lookup, index, ce)
+		if (intel_context_is_pinned(ce))
+			guc_cancel_context_requests(ce);
 
-	ENGINE_TRACE(engine, "depth->%d\n",
-		     atomic_read(&engine->sched_engine->tasklet.count));
+	guc_cancel_sched_engine_requests(guc->sched_engine);
+
+	/* GuC is blown away, drop all references to contexts */
+	xa_destroy(&guc->context_lookup);
+}
+
+void intel_guc_submission_reset_finish(struct intel_guc *guc)
+{
+	/* Reset called during driver load or during wedge? */
+	if (unlikely(!guc_submission_initialized(guc) ||
+		     test_bit(I915_WEDGED, &guc_to_gt(guc)->reset.flags)))
+		return;
+
+	/*
+	 * Technically possible for either of these values to be non-zero here,
+	 * but very unlikely + harmless. Regardless let's add a warn so we can
+	 * see in CI if this happens frequently / a precursor to taking down the
+	 * machine.
+	 */
+	GEM_WARN_ON(atomic_read(&guc->outstanding_submission_g2h));
+	atomic_set(&guc->outstanding_submission_g2h, 0);
+
+	enable_submission(guc);
 }
 
 /*
@@ -656,6 +956,9 @@  static int guc_bypass_tasklet_submit(struct intel_guc *guc,
 	else
 		trace_i915_request_guc_submit(rq);
 
+	if (unlikely(ret == -EIO))
+		disable_submission(guc);
+
 	return ret;
 }
 
@@ -668,7 +971,8 @@  static void guc_submit_request(struct i915_request *rq)
 	/* Will be called from irq-context when using foreign fences. */
 	spin_lock_irqsave(&sched_engine->lock, flags);
 
-	if (guc->stalled_request || !i915_sched_engine_is_empty(sched_engine))
+	if (submission_disabled(guc) || guc->stalled_request ||
+	    !i915_sched_engine_is_empty(sched_engine))
 		queue_request(sched_engine, rq, rq_prio(rq));
 	else if (guc_bypass_tasklet_submit(guc, rq) == -EBUSY)
 		tasklet_hi_schedule(&sched_engine->tasklet);
@@ -805,7 +1109,8 @@  static void unpin_guc_id(struct intel_guc *guc, struct intel_context *ce)
 
 static int __guc_action_register_context(struct intel_guc *guc,
 					 u32 guc_id,
-					 u32 offset)
+					 u32 offset,
+					 bool loop)
 {
 	u32 action[] = {
 		INTEL_GUC_ACTION_REGISTER_CONTEXT,
@@ -813,10 +1118,10 @@  static int __guc_action_register_context(struct intel_guc *guc,
 		offset,
 	};
 
-	return guc_submission_busy_loop(guc, action, ARRAY_SIZE(action), 0, true);
+	return guc_submission_busy_loop(guc, action, ARRAY_SIZE(action), 0, loop);
 }
 
-static int register_context(struct intel_context *ce)
+static int register_context(struct intel_context *ce, bool loop)
 {
 	struct intel_guc *guc = ce_to_guc(ce);
 	u32 offset = intel_guc_ggtt_offset(guc, guc->lrc_desc_pool) +
@@ -824,11 +1129,12 @@  static int register_context(struct intel_context *ce)
 
 	trace_intel_context_register(ce);
 
-	return __guc_action_register_context(guc, ce->guc_id, offset);
+	return __guc_action_register_context(guc, ce->guc_id, offset, loop);
 }
 
 static int __guc_action_deregister_context(struct intel_guc *guc,
-					   u32 guc_id)
+					   u32 guc_id,
+					   bool loop)
 {
 	u32 action[] = {
 		INTEL_GUC_ACTION_DEREGISTER_CONTEXT,
@@ -836,16 +1142,16 @@  static int __guc_action_deregister_context(struct intel_guc *guc,
 	};
 
 	return guc_submission_busy_loop(guc, action, ARRAY_SIZE(action),
-					G2H_LEN_DW_DEREGISTER_CONTEXT, true);
+					G2H_LEN_DW_DEREGISTER_CONTEXT, loop);
 }
 
-static int deregister_context(struct intel_context *ce, u32 guc_id)
+static int deregister_context(struct intel_context *ce, u32 guc_id, bool loop)
 {
 	struct intel_guc *guc = ce_to_guc(ce);
 
 	trace_intel_context_deregister(ce);
 
-	return __guc_action_deregister_context(guc, guc_id);
+	return __guc_action_deregister_context(guc, guc_id, loop);
 }
 
 static intel_engine_mask_t adjust_engine_mask(u8 class, intel_engine_mask_t mask)
@@ -874,7 +1180,7 @@  static void guc_context_policy_init(struct intel_engine_cs *engine,
 	desc->preemption_timeout = CONTEXT_POLICY_DEFAULT_PREEMPTION_TIME_US;
 }
 
-static int guc_lrc_desc_pin(struct intel_context *ce)
+static int guc_lrc_desc_pin(struct intel_context *ce, bool loop)
 {
 	struct intel_runtime_pm *runtime_pm =
 		&ce->engine->gt->i915->runtime_pm;
@@ -920,18 +1226,44 @@  static int guc_lrc_desc_pin(struct intel_context *ce)
 	 */
 	if (context_registered) {
 		trace_intel_context_steal_guc_id(ce);
-		set_context_wait_for_deregister_to_register(ce);
-		intel_context_get(ce);
+		if (!loop) {
+			set_context_wait_for_deregister_to_register(ce);
+			intel_context_get(ce);
+		} else {
+			bool disabled;
+			unsigned long flags;
+
+			/* Seal race with Reset */
+			spin_lock_irqsave(&ce->guc_state.lock, flags);
+			disabled = submission_disabled(guc);
+			if (likely(!disabled)) {
+				set_context_wait_for_deregister_to_register(ce);
+				intel_context_get(ce);
+			}
+			spin_unlock_irqrestore(&ce->guc_state.lock, flags);
+			if (unlikely(disabled)) {
+				reset_lrc_desc(guc, desc_idx);
+				return 0;	/* Will get registered later */
+			}
+		}
 
 		/*
 		 * If stealing the guc_id, this ce has the same guc_id as the
 		 * context whos guc_id was stole.
 		 */
 		with_intel_runtime_pm(runtime_pm, wakeref)
-			ret = deregister_context(ce, ce->guc_id);
+			ret = deregister_context(ce, ce->guc_id, loop);
+		if (unlikely(ret == -EBUSY)) {
+			clr_context_wait_for_deregister_to_register(ce);
+			intel_context_put(ce);
+		}
 	} else {
 		with_intel_runtime_pm(runtime_pm, wakeref)
-			ret = register_context(ce);
+			ret = register_context(ce, loop);
+		if (unlikely(ret == -EBUSY))
+			reset_lrc_desc(guc, desc_idx);
+		else if (unlikely(ret == -ENODEV))
+			ret = 0;	/* Will get registered later */
 	}
 
 	return ret;
@@ -994,7 +1326,6 @@  static void __guc_context_sched_disable(struct intel_guc *guc,
 	GEM_BUG_ON(guc_id == GUC_INVALID_LRC_ID);
 
 	trace_intel_context_sched_disable(ce);
-	intel_context_get(ce);
 
 	guc_submission_busy_loop(guc, action, ARRAY_SIZE(action),
 				 G2H_LEN_DW_SCHED_CONTEXT_MODE_SET, true);
@@ -1004,6 +1335,7 @@  static u16 prep_context_pending_disable(struct intel_context *ce)
 {
 	set_context_pending_disable(ce);
 	clr_context_enabled(ce);
+	intel_context_get(ce);
 
 	return ce->guc_id;
 }
@@ -1016,7 +1348,7 @@  static void guc_context_sched_disable(struct intel_context *ce)
 	u16 guc_id;
 	intel_wakeref_t wakeref;
 
-	if (context_guc_id_invalid(ce) ||
+	if (submission_disabled(guc) || context_guc_id_invalid(ce) ||
 	    !lrc_desc_registered(guc, ce->guc_id)) {
 		clr_context_enabled(ce);
 		goto unpin;
@@ -1034,6 +1366,7 @@  static void guc_context_sched_disable(struct intel_context *ce)
 	 * request doesn't slip through the 'context_pending_disable' fence.
 	 */
 	if (unlikely(atomic_add_unless(&ce->pin_count, -2, 2))) {
+		spin_unlock_irqrestore(&ce->guc_state.lock, flags);
 		return;
 	}
 	guc_id = prep_context_pending_disable(ce);
@@ -1050,19 +1383,13 @@  static void guc_context_sched_disable(struct intel_context *ce)
 
 static inline void guc_lrc_desc_unpin(struct intel_context *ce)
 {
-	struct intel_engine_cs *engine = ce->engine;
-	struct intel_guc *guc = &engine->gt->uc.guc;
-	unsigned long flags;
+	struct intel_guc *guc = ce_to_guc(ce);
 
 	GEM_BUG_ON(!lrc_desc_registered(guc, ce->guc_id));
 	GEM_BUG_ON(ce != __get_context(guc, ce->guc_id));
 	GEM_BUG_ON(context_enabled(ce));
 
-	spin_lock_irqsave(&ce->guc_state.lock, flags);
-	set_context_destroyed(ce);
-	spin_unlock_irqrestore(&ce->guc_state.lock, flags);
-
-	deregister_context(ce, ce->guc_id);
+	deregister_context(ce, ce->guc_id, true);
 }
 
 static void __guc_context_destroy(struct intel_context *ce)
@@ -1090,13 +1417,15 @@  static void guc_context_destroy(struct kref *kref)
 	struct intel_guc *guc = &ce->engine->gt->uc.guc;
 	intel_wakeref_t wakeref;
 	unsigned long flags;
+	bool disabled;
 
 	/*
 	 * If the guc_id is invalid this context has been stolen and we can free
 	 * it immediately. Also can be freed immediately if the context is not
 	 * registered with the GuC.
 	 */
-	if (context_guc_id_invalid(ce) ||
+	if (submission_disabled(guc) ||
+	    context_guc_id_invalid(ce) ||
 	    !lrc_desc_registered(guc, ce->guc_id)) {
 		release_guc_id(guc, ce);
 		__guc_context_destroy(ce);
@@ -1123,6 +1452,18 @@  static void guc_context_destroy(struct kref *kref)
 		list_del_init(&ce->guc_id_link);
 	spin_unlock_irqrestore(&guc->contexts_lock, flags);
 
+	/* Seal race with Reset */
+	spin_lock_irqsave(&ce->guc_state.lock, flags);
+	disabled = submission_disabled(guc);
+	if (likely(!disabled))
+		set_context_destroyed(ce);
+	spin_unlock_irqrestore(&ce->guc_state.lock, flags);
+	if (unlikely(disabled)) {
+		release_guc_id(guc, ce);
+		__guc_context_destroy(ce);
+		return;
+	}
+
 	/*
 	 * We defer GuC context deregistration until the context is destroyed
 	 * in order to save on CTBs. With this optimization ideally we only need
@@ -1145,6 +1486,33 @@  static int guc_context_alloc(struct intel_context *ce)
 	return lrc_alloc(ce, ce->engine);
 }
 
+static void add_to_context(struct i915_request *rq)
+{
+	struct intel_context *ce = rq->context;
+
+	spin_lock(&ce->guc_active.lock);
+	list_move_tail(&rq->sched.link, &ce->guc_active.requests);
+	spin_unlock(&ce->guc_active.lock);
+}
+
+static void remove_from_context(struct i915_request *rq)
+{
+	struct intel_context *ce = rq->context;
+
+	spin_lock_irq(&ce->guc_active.lock);
+
+	list_del_init(&rq->sched.link);
+	clear_bit(I915_FENCE_FLAG_PQUEUE, &rq->fence.flags);
+
+	/* Prevent further __await_execution() registering a cb, then flush */
+	set_bit(I915_FENCE_FLAG_ACTIVE, &rq->fence.flags);
+
+	spin_unlock_irq(&ce->guc_active.lock);
+
+	atomic_dec(&ce->guc_id_ref);
+	i915_request_notify_execute_cb_imm(rq);
+}
+
 static const struct intel_context_ops guc_context_ops = {
 	.alloc = guc_context_alloc,
 
@@ -1183,8 +1551,6 @@  static void guc_signal_context_fence(struct intel_context *ce)
 {
 	unsigned long flags;
 
-	GEM_BUG_ON(!context_wait_for_deregister_to_register(ce));
-
 	spin_lock_irqsave(&ce->guc_state.lock, flags);
 	clr_context_wait_for_deregister_to_register(ce);
 	__guc_signal_context_fence(ce);
@@ -1193,8 +1559,9 @@  static void guc_signal_context_fence(struct intel_context *ce)
 
 static bool context_needs_register(struct intel_context *ce, bool new_guc_id)
 {
-	return new_guc_id || test_bit(CONTEXT_LRCA_DIRTY, &ce->flags) ||
-		!lrc_desc_registered(ce_to_guc(ce), ce->guc_id);
+	return (new_guc_id || test_bit(CONTEXT_LRCA_DIRTY, &ce->flags) ||
+		!lrc_desc_registered(ce_to_guc(ce), ce->guc_id)) &&
+		!submission_disabled(ce_to_guc(ce));
 }
 
 static int guc_request_alloc(struct i915_request *rq)
@@ -1252,8 +1619,12 @@  static int guc_request_alloc(struct i915_request *rq)
 	if (unlikely(ret < 0))
 		return ret;;
 	if (context_needs_register(ce, !!ret)) {
-		ret = guc_lrc_desc_pin(ce);
+		ret = guc_lrc_desc_pin(ce, true);
 		if (unlikely(ret)) {	/* unwind */
+			if (ret == -EIO) {
+				disable_submission(guc);
+				goto out;	/* GPU will be reset */
+			}
 			atomic_dec(&ce->guc_id_ref);
 			unpin_guc_id(guc, ce);
 			return ret;
@@ -1290,20 +1661,6 @@  static int guc_request_alloc(struct i915_request *rq)
 	return 0;
 }
 
-static struct intel_engine_cs *
-guc_virtual_get_sibling(struct intel_engine_cs *ve, unsigned int sibling)
-{
-	struct intel_engine_cs *engine;
-	intel_engine_mask_t tmp, mask = ve->mask;
-	unsigned int num_siblings = 0;
-
-	for_each_engine_masked(engine, ve->gt, mask, tmp)
-		if (num_siblings++ == sibling)
-			return engine;
-
-	return NULL;
-}
-
 static int guc_virtual_context_pre_pin(struct intel_context *ce,
 				       struct i915_gem_ww_ctx *ww,
 				       void **vaddr)
@@ -1512,7 +1869,7 @@  static inline void guc_kernel_context_pin(struct intel_guc *guc,
 {
 	if (context_guc_id_invalid(ce))
 		pin_guc_id(guc, ce);
-	guc_lrc_desc_pin(ce);
+	guc_lrc_desc_pin(ce, true);
 }
 
 static inline void guc_init_lrc_mapping(struct intel_guc *guc)
@@ -1578,13 +1935,15 @@  static void guc_default_vfuncs(struct intel_engine_cs *engine)
 	engine->cops = &guc_context_ops;
 	engine->request_alloc = guc_request_alloc;
 	engine->bump_serial = guc_bump_serial;
+	engine->add_active_request = add_to_context;
+	engine->remove_active_request = remove_from_context;
 
 	engine->sched_engine->schedule = i915_schedule;
 
-	engine->reset.prepare = guc_reset_prepare;
-	engine->reset.rewind = guc_reset_rewind;
-	engine->reset.cancel = guc_reset_cancel;
-	engine->reset.finish = guc_reset_finish;
+	engine->reset.prepare = guc_reset_nop;
+	engine->reset.rewind = guc_rewind_nop;
+	engine->reset.cancel = guc_reset_nop;
+	engine->reset.finish = guc_reset_nop;
 
 	engine->emit_flush = gen8_emit_flush_xcs;
 	engine->emit_init_breadcrumb = gen8_emit_init_breadcrumb;
@@ -1757,7 +2116,7 @@  int intel_guc_deregister_done_process_msg(struct intel_guc *guc,
 		 * register this context.
 		 */
 		with_intel_runtime_pm(runtime_pm, wakeref)
-			register_context(ce);
+			register_context(ce, true);
 		guc_signal_context_fence(ce);
 		intel_context_put(ce);
 	} else if (context_destroyed(ce)) {
@@ -1939,6 +2298,10 @@  guc_create_virtual(struct intel_engine_cs **siblings, unsigned int count)
 				 "v%dx%d", ve->base.class, count);
 			ve->base.context_size = sibling->context_size;
 
+			ve->base.add_active_request =
+				sibling->add_active_request;
+			ve->base.remove_active_request =
+				sibling->remove_active_request;
 			ve->base.emit_bb_start = sibling->emit_bb_start;
 			ve->base.emit_flush = sibling->emit_flush;
 			ve->base.emit_init_breadcrumb =
diff --git a/drivers/gpu/drm/i915/gt/uc/intel_uc.c b/drivers/gpu/drm/i915/gt/uc/intel_uc.c
index 6d8b9233214e..f0b02200aa01 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_uc.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_uc.c
@@ -565,12 +565,49 @@  void intel_uc_reset_prepare(struct intel_uc *uc)
 {
 	struct intel_guc *guc = &uc->guc;
 
-	if (!intel_guc_is_ready(guc))
+
+	/* Nothing to do if GuC isn't supported */
+	if (!intel_uc_supports_guc(uc))
 		return;
 
+	/* Firmware expected to be running when this function is called */
+	if (!intel_guc_is_ready(guc))
+		goto sanitize;
+
+	if (intel_uc_uses_guc_submission(uc))
+		intel_guc_submission_reset_prepare(guc);
+
+sanitize:
 	__uc_sanitize(uc);
 }
 
+void intel_uc_reset(struct intel_uc *uc, bool stalled)
+{
+	struct intel_guc *guc = &uc->guc;
+
+	/* Firmware can not be running when this function is called  */
+	if (intel_uc_uses_guc_submission(uc))
+		intel_guc_submission_reset(guc, stalled);
+}
+
+void intel_uc_reset_finish(struct intel_uc *uc)
+{
+	struct intel_guc *guc = &uc->guc;
+
+	/* Firmware expected to be running when this function is called */
+	if (intel_guc_is_fw_running(guc) && intel_uc_uses_guc_submission(uc))
+		intel_guc_submission_reset_finish(guc);
+}
+
+void intel_uc_cancel_requests(struct intel_uc *uc)
+{
+	struct intel_guc *guc = &uc->guc;
+
+	/* Firmware can not be running when this function is called  */
+	if (intel_uc_uses_guc_submission(uc))
+		intel_guc_submission_cancel_requests(guc);
+}
+
 void intel_uc_runtime_suspend(struct intel_uc *uc)
 {
 	struct intel_guc *guc = &uc->guc;
diff --git a/drivers/gpu/drm/i915/gt/uc/intel_uc.h b/drivers/gpu/drm/i915/gt/uc/intel_uc.h
index c4cef885e984..eaa3202192ac 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_uc.h
+++ b/drivers/gpu/drm/i915/gt/uc/intel_uc.h
@@ -37,6 +37,9 @@  void intel_uc_driver_late_release(struct intel_uc *uc);
 void intel_uc_driver_remove(struct intel_uc *uc);
 void intel_uc_init_mmio(struct intel_uc *uc);
 void intel_uc_reset_prepare(struct intel_uc *uc);
+void intel_uc_reset(struct intel_uc *uc, bool stalled);
+void intel_uc_reset_finish(struct intel_uc *uc);
+void intel_uc_cancel_requests(struct intel_uc *uc);
 void intel_uc_suspend(struct intel_uc *uc);
 void intel_uc_runtime_suspend(struct intel_uc *uc);
 int intel_uc_resume(struct intel_uc *uc);
diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
index dec5a35c9aa2..192784875a1d 100644
--- a/drivers/gpu/drm/i915/i915_request.c
+++ b/drivers/gpu/drm/i915/i915_request.c
@@ -194,7 +194,7 @@  static bool irq_work_imm(struct irq_work *wrk)
 	return false;
 }
 
-static void __notify_execute_cb_imm(struct i915_request *rq)
+void i915_request_notify_execute_cb_imm(struct i915_request *rq)
 {
 	__notify_execute_cb(rq, irq_work_imm);
 }
@@ -268,37 +268,6 @@  i915_request_active_engine(struct i915_request *rq,
 	return ret;
 }
 
-
-static void remove_from_engine(struct i915_request *rq)
-{
-	struct intel_engine_cs *engine, *locked;
-
-	/*
-	 * Virtual engines complicate acquiring the engine timeline lock,
-	 * as their rq->engine pointer is not stable until under that
-	 * engine lock. The simple ploy we use is to take the lock then
-	 * check that the rq still belongs to the newly locked engine.
-	 */
-	locked = READ_ONCE(rq->engine);
-	spin_lock_irq(&locked->sched_engine->lock);
-	while (unlikely(locked != (engine = READ_ONCE(rq->engine)))) {
-		spin_unlock(&locked->sched_engine->lock);
-		spin_lock(&engine->sched_engine->lock);
-		locked = engine;
-	}
-	list_del_init(&rq->sched.link);
-
-	clear_bit(I915_FENCE_FLAG_PQUEUE, &rq->fence.flags);
-	clear_bit(I915_FENCE_FLAG_HOLD, &rq->fence.flags);
-
-	/* Prevent further __await_execution() registering a cb, then flush */
-	set_bit(I915_FENCE_FLAG_ACTIVE, &rq->fence.flags);
-
-	spin_unlock_irq(&locked->sched_engine->lock);
-
-	__notify_execute_cb_imm(rq);
-}
-
 static void __rq_init_watchdog(struct i915_request *rq)
 {
 	rq->watchdog.timer.function = NULL;
@@ -395,9 +364,7 @@  bool i915_request_retire(struct i915_request *rq)
 	 * after removing the breadcrumb and signaling it, so that we do not
 	 * inadvertently attach the breadcrumb to a completed request.
 	 */
-	if (!list_empty(&rq->sched.link))
-		remove_from_engine(rq);
-	atomic_dec(&rq->context->guc_id_ref);
+	rq->engine->remove_active_request(rq);
 	GEM_BUG_ON(!llist_empty(&rq->execute_cb));
 
 	__list_del_entry(&rq->link); /* poison neither prev/next (RCU walks) */
@@ -539,7 +506,7 @@  __await_execution(struct i915_request *rq,
 	if (llist_add(&cb->work.node.llist, &signal->execute_cb)) {
 		if (i915_request_is_active(signal) ||
 		    __request_in_flight(signal))
-			__notify_execute_cb_imm(signal);
+			i915_request_notify_execute_cb_imm(signal);
 	}
 
 	return 0;
@@ -676,7 +643,7 @@  bool __i915_request_submit(struct i915_request *request)
 	result = true;
 
 	GEM_BUG_ON(test_bit(I915_FENCE_FLAG_ACTIVE, &request->fence.flags));
-	list_move_tail(&request->sched.link, &engine->sched_engine->requests);
+	engine->add_active_request(request);
 active:
 	clear_bit(I915_FENCE_FLAG_PQUEUE, &request->fence.flags);
 	set_bit(I915_FENCE_FLAG_ACTIVE, &request->fence.flags);
diff --git a/drivers/gpu/drm/i915/i915_request.h b/drivers/gpu/drm/i915/i915_request.h
index f870cd75a001..bcc6340c505e 100644
--- a/drivers/gpu/drm/i915/i915_request.h
+++ b/drivers/gpu/drm/i915/i915_request.h
@@ -649,4 +649,6 @@  bool
 i915_request_active_engine(struct i915_request *rq,
 			   struct intel_engine_cs **active);
 
+void i915_request_notify_execute_cb_imm(struct i915_request *rq);
+
 #endif /* I915_REQUEST_H */