diff mbox series

[v5,2/5] drm/i915: Watchdog timeout: IRQ handler for gen8+

Message ID 20190322234118.65980-3-carlos.santa@intel.com (mailing list archive)
State New, archived
Headers show
Series GEN8+ GPU Watchdog Reset Support | expand

Commit Message

Santa, Carlos March 22, 2019, 11:41 p.m. UTC
From: Michel Thierry <michel.thierry@intel.com>

*** General ***

Watchdog timeout (or "media engine reset") is a feature that allows
userland applications to enable hang detection on individual batch buffers.
The detection mechanism itself is mostly bound to the hardware and the only
thing that the driver needs to do to support this form of hang detection
is to implement the interrupt handling support as well as watchdog command
emission before and after the emitted batch buffer start instruction in the
ring buffer.

The principle of the hang detection mechanism is as follows:

1. Once the decision has been made to enable watchdog timeout for a
particular batch buffer and the driver is in the process of emitting the
batch buffer start instruction into the ring buffer it also emits a
watchdog timer start instruction before and a watchdog timer cancellation
instruction after the batch buffer start instruction in the ring buffer.

2. Once the GPU execution reaches the watchdog timer start instruction
the hardware watchdog counter is started by the hardware. The counter
keeps counting until either reaching a previously configured threshold
value or the timer cancellation instruction is executed.

2a. If the counter reaches the threshold value the hardware fires a
watchdog interrupt that is picked up by the watchdog interrupt handler.
This means that a hang has been detected and the driver needs to deal with
it the same way it would deal with a engine hang detected by the periodic
hang checker. The only difference between the two is that we already blamed
the active request (to ensure an engine reset).

2b. If the batch buffer completes and the execution reaches the watchdog
cancellation instruction before the watchdog counter reaches its
threshold value the watchdog is cancelled and nothing more comes of it.
No hang is detected.

Note about future interaction with preemption: Preemption could happen
in a command sequence prior to watchdog counter getting disabled,
resulting in watchdog being triggered following preemption (e.g. when
watchdog had been enabled in the low priority batch). The driver will
need to explicitly disable the watchdog counter as part of the
preemption sequence.

*** This patch introduces: ***

1. IRQ handler code for watchdog timeout allowing direct hang recovery
based on hardware-driven hang detection, which then integrates directly
with the hang recovery path. This is independent of having per-engine reset
or just full gpu reset.

2. Watchdog specific register information.

Currently the render engine and all available media engines support
watchdog timeout (VECS is only supported in GEN9). The specifications elude
to the BCS engine being supported but that is currently not supported by
this commit.

Note that the value to stop the counter is different between render and
non-render engines in GEN8; GEN9 onwards it's the same.

v2: Move irq handler to tasklet, arm watchdog for a 2nd time to check
against false-positives.

v3: Don't use high priority tasklet, use engine_last_submit while
checking for false-positives. From GEN9 onwards, the stop counter bit is
the same for all engines.

v4: Remove unnecessary brackets, use current_seqno to mark the request
as guilty in the hangcheck/capture code.

v5: Rebased after RESET_ENGINEs flag.

v6: Don't capture error state in case of watchdog timeout. The capture
process is time consuming and this will align to what happens when we
use GuC to handle the watchdog timeout. (Chris)

v7: Rebase.

v8: Rebase, use HZ to reschedule.

v9: Rebase, get forcewake domains in function (no longer in execlists
struct).

v10: Rebase.

v11: Rebase,
     remove extra braces (Tvrtko),
     implement watchdog_to_clock_counts helper (Tvrtko),
     Move tasklet_kill(watchdog_tasklet) inside intel_engines (Tvrtko),
     Use a global heartbeat seqno instead of engine seqno (Chris)
     Make all engines checks all class based checks (Tvrtko)

v12: Rebase,
     Reset immediately upon entering the IRQ (Chris)
     Make reset_engine_to_str a helper (Tvrtko)
     Rename watchdog_irq_handler as watchdog_tasklet (Tvrtko)
     Let the compiler itself do the inline (Tvrtko)

v13: Rebase
v14: Rebase, skip checking for the guilty seqno in the tasklet (Tvrtko)

Cc: Antonio Argenziano <antonio.argenziano@intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Signed-off-by: Michel Thierry <michel.thierry@intel.com>
Signed-off-by: Carlos Santa <carlos.santa@intel.com>
---
 drivers/gpu/drm/i915/i915_gpu_error.h     |  4 ++
 drivers/gpu/drm/i915/i915_irq.c           | 14 ++++--
 drivers/gpu/drm/i915/i915_reg.h           |  6 +++
 drivers/gpu/drm/i915/i915_reset.c         | 20 +++++++++
 drivers/gpu/drm/i915/i915_reset.h         |  6 +++
 drivers/gpu/drm/i915/intel_engine_cs.c    |  1 +
 drivers/gpu/drm/i915/intel_engine_types.h |  5 +++
 drivers/gpu/drm/i915/intel_hangcheck.c    | 11 +----
 drivers/gpu/drm/i915/intel_lrc.c          | 52 +++++++++++++++++++++++
 9 files changed, 107 insertions(+), 12 deletions(-)

Comments

Tvrtko Ursulin March 25, 2019, 10 a.m. UTC | #1
On 22/03/2019 23:41, Carlos Santa wrote:
> From: Michel Thierry <michel.thierry@intel.com>
> 
> *** General ***
> 
> Watchdog timeout (or "media engine reset") is a feature that allows
> userland applications to enable hang detection on individual batch buffers.
> The detection mechanism itself is mostly bound to the hardware and the only
> thing that the driver needs to do to support this form of hang detection
> is to implement the interrupt handling support as well as watchdog command
> emission before and after the emitted batch buffer start instruction in the
> ring buffer.
> 
> The principle of the hang detection mechanism is as follows:
> 
> 1. Once the decision has been made to enable watchdog timeout for a
> particular batch buffer and the driver is in the process of emitting the
> batch buffer start instruction into the ring buffer it also emits a
> watchdog timer start instruction before and a watchdog timer cancellation
> instruction after the batch buffer start instruction in the ring buffer.
> 
> 2. Once the GPU execution reaches the watchdog timer start instruction
> the hardware watchdog counter is started by the hardware. The counter
> keeps counting until either reaching a previously configured threshold
> value or the timer cancellation instruction is executed.
> 
> 2a. If the counter reaches the threshold value the hardware fires a
> watchdog interrupt that is picked up by the watchdog interrupt handler.
> This means that a hang has been detected and the driver needs to deal with
> it the same way it would deal with a engine hang detected by the periodic
> hang checker. The only difference between the two is that we already blamed
> the active request (to ensure an engine reset).
> 
> 2b. If the batch buffer completes and the execution reaches the watchdog
> cancellation instruction before the watchdog counter reaches its
> threshold value the watchdog is cancelled and nothing more comes of it.
> No hang is detected.
> 
> Note about future interaction with preemption: Preemption could happen
> in a command sequence prior to watchdog counter getting disabled,
> resulting in watchdog being triggered following preemption (e.g. when
> watchdog had been enabled in the low priority batch). The driver will
> need to explicitly disable the watchdog counter as part of the
> preemption sequence.
> 
> *** This patch introduces: ***
> 
> 1. IRQ handler code for watchdog timeout allowing direct hang recovery
> based on hardware-driven hang detection, which then integrates directly
> with the hang recovery path. This is independent of having per-engine reset
> or just full gpu reset.
> 
> 2. Watchdog specific register information.
> 
> Currently the render engine and all available media engines support
> watchdog timeout (VECS is only supported in GEN9). The specifications elude
> to the BCS engine being supported but that is currently not supported by
> this commit.
> 
> Note that the value to stop the counter is different between render and
> non-render engines in GEN8; GEN9 onwards it's the same.
> 
> v2: Move irq handler to tasklet, arm watchdog for a 2nd time to check
> against false-positives.
> 
> v3: Don't use high priority tasklet, use engine_last_submit while
> checking for false-positives. From GEN9 onwards, the stop counter bit is
> the same for all engines.
> 
> v4: Remove unnecessary brackets, use current_seqno to mark the request
> as guilty in the hangcheck/capture code.
> 
> v5: Rebased after RESET_ENGINEs flag.
> 
> v6: Don't capture error state in case of watchdog timeout. The capture
> process is time consuming and this will align to what happens when we
> use GuC to handle the watchdog timeout. (Chris)
> 
> v7: Rebase.
> 
> v8: Rebase, use HZ to reschedule.
> 
> v9: Rebase, get forcewake domains in function (no longer in execlists
> struct).
> 
> v10: Rebase.
> 
> v11: Rebase,
>       remove extra braces (Tvrtko),
>       implement watchdog_to_clock_counts helper (Tvrtko),
>       Move tasklet_kill(watchdog_tasklet) inside intel_engines (Tvrtko),
>       Use a global heartbeat seqno instead of engine seqno (Chris)
>       Make all engines checks all class based checks (Tvrtko)
> 
> v12: Rebase,
>       Reset immediately upon entering the IRQ (Chris)
>       Make reset_engine_to_str a helper (Tvrtko)
>       Rename watchdog_irq_handler as watchdog_tasklet (Tvrtko)
>       Let the compiler itself do the inline (Tvrtko)
> 
> v13: Rebase
> v14: Rebase, skip checking for the guilty seqno in the tasklet (Tvrtko)

IIRC I only asked about it so I guess you tried it and it works well?

Can you also post the IGTs so we can see the test coverage?

Regards,

Tvrtko

> 
> Cc: Antonio Argenziano <antonio.argenziano@intel.com>
> Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
> Signed-off-by: Michel Thierry <michel.thierry@intel.com>
> Signed-off-by: Carlos Santa <carlos.santa@intel.com>
> ---
>   drivers/gpu/drm/i915/i915_gpu_error.h     |  4 ++
>   drivers/gpu/drm/i915/i915_irq.c           | 14 ++++--
>   drivers/gpu/drm/i915/i915_reg.h           |  6 +++
>   drivers/gpu/drm/i915/i915_reset.c         | 20 +++++++++
>   drivers/gpu/drm/i915/i915_reset.h         |  6 +++
>   drivers/gpu/drm/i915/intel_engine_cs.c    |  1 +
>   drivers/gpu/drm/i915/intel_engine_types.h |  5 +++
>   drivers/gpu/drm/i915/intel_hangcheck.c    | 11 +----
>   drivers/gpu/drm/i915/intel_lrc.c          | 52 +++++++++++++++++++++++
>   9 files changed, 107 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_gpu_error.h b/drivers/gpu/drm/i915/i915_gpu_error.h
> index 99d6b7b270c2..6cf6a8679b26 100644
> --- a/drivers/gpu/drm/i915/i915_gpu_error.h
> +++ b/drivers/gpu/drm/i915/i915_gpu_error.h
> @@ -203,6 +203,9 @@ struct i915_gpu_error {
>   	 * any global resources that may be clobber by the reset (such as
>   	 * FENCE registers).
>   	 *
> +	 * #I915_RESET_WATCHDOG - When hw detects a hang before us, we can use
> +	 * I915_RESET_WATCHDOG to report the hang detection cause accurately.
> +	 *
>   	 * #I915_RESET_ENGINE[num_engines] - Since the driver doesn't need to
>   	 * acquire the struct_mutex to reset an engine, we need an explicit
>   	 * flag to prevent two concurrent reset attempts in the same engine.
> @@ -218,6 +221,7 @@ struct i915_gpu_error {
>   #define I915_RESET_BACKOFF	0
>   #define I915_RESET_MODESET	1
>   #define I915_RESET_ENGINE	2
> +#define I915_RESET_WATCHDOG	3
>   #define I915_WEDGED		(BITS_PER_LONG - 1)
>   
>   	/** Number of times the device has been reset (global) */
> diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
> index 82d487189a34..e64994be25c3 100644
> --- a/drivers/gpu/drm/i915/i915_irq.c
> +++ b/drivers/gpu/drm/i915/i915_irq.c
> @@ -1466,6 +1466,9 @@ gen8_cs_irq_handler(struct intel_engine_cs *engine, u32 iir)
>   
>   	if (tasklet)
>   		tasklet_hi_schedule(&engine->execlists.tasklet);
> +
> +	if (iir & GT_GEN8_WATCHDOG_INTERRUPT)
> +		tasklet_schedule(&engine->execlists.watchdog_tasklet);
>   }
>   
>   static void gen8_gt_irq_ack(struct drm_i915_private *i915,
> @@ -3892,20 +3895,25 @@ static void gen8_gt_irq_postinstall(struct drm_i915_private *dev_priv)
>   	u32 gt_interrupts[] = {
>   		(GT_RENDER_USER_INTERRUPT << GEN8_RCS_IRQ_SHIFT |
>   		 GT_CONTEXT_SWITCH_INTERRUPT << GEN8_RCS_IRQ_SHIFT |
> +		 GT_GEN8_WATCHDOG_INTERRUPT << GEN8_RCS_IRQ_SHIFT |
>   		 GT_RENDER_USER_INTERRUPT << GEN8_BCS_IRQ_SHIFT |
>   		 GT_CONTEXT_SWITCH_INTERRUPT << GEN8_BCS_IRQ_SHIFT),
> -
>   		(GT_RENDER_USER_INTERRUPT << GEN8_VCS0_IRQ_SHIFT |
>   		 GT_CONTEXT_SWITCH_INTERRUPT << GEN8_VCS0_IRQ_SHIFT |
> +		 GT_GEN8_WATCHDOG_INTERRUPT << GEN8_VCS0_IRQ_SHIFT |
>   		 GT_RENDER_USER_INTERRUPT << GEN8_VCS1_IRQ_SHIFT |
> -		 GT_CONTEXT_SWITCH_INTERRUPT << GEN8_VCS1_IRQ_SHIFT),
> -
> +		 GT_CONTEXT_SWITCH_INTERRUPT << GEN8_VCS1_IRQ_SHIFT |
> +		 GT_GEN8_WATCHDOG_INTERRUPT << GEN8_VCS1_IRQ_SHIFT),
>   		0,
>   
>   		(GT_RENDER_USER_INTERRUPT << GEN8_VECS_IRQ_SHIFT |
>   		 GT_CONTEXT_SWITCH_INTERRUPT << GEN8_VECS_IRQ_SHIFT)
>   	};
>   
> +	/* VECS watchdog is only available in skl+ */
> +	if (INTEL_GEN(dev_priv) >= 9)
> +		gt_interrupts[3] |= GT_GEN8_WATCHDOG_INTERRUPT;
> +
>   	dev_priv->pm_ier = 0x0;
>   	dev_priv->pm_imr = ~dev_priv->pm_ier;
>   	GEN8_IRQ_INIT_NDX(GT, 0, ~gt_interrupts[0], gt_interrupts[0]);
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index 9b69cec21f7b..ac8d984e16ae 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -2363,6 +2363,11 @@ enum i915_power_well_id {
>   #define RING_START(base)	_MMIO((base) + 0x38)
>   #define RING_CTL(base)		_MMIO((base) + 0x3c)
>   #define   RING_CTL_SIZE(size)	((size) - PAGE_SIZE) /* in bytes -> pages */
> +#define RING_CNTR(base)		_MMIO((base) + 0x178)
> +#define GEN8_WATCHDOG_ENABLE		0
> +#define GEN8_WATCHDOG_DISABLE		1
> +#define GEN8_XCS_WATCHDOG_DISABLE	0xFFFFFFFF /* GEN8 & non-render only */
> +#define RING_THRESH(base)	_MMIO((base) + 0x17C)
>   #define RING_SYNC_0(base)	_MMIO((base) + 0x40)
>   #define RING_SYNC_1(base)	_MMIO((base) + 0x44)
>   #define RING_SYNC_2(base)	_MMIO((base) + 0x48)
> @@ -2925,6 +2930,7 @@ enum i915_power_well_id {
>   #define GT_BSD_USER_INTERRUPT			(1 << 12)
>   #define GT_RENDER_L3_PARITY_ERROR_INTERRUPT_S1	(1 << 11) /* hsw+; rsvd on snb, ivb, vlv */
>   #define GT_CONTEXT_SWITCH_INTERRUPT		(1 <<  8)
> +#define GT_GEN8_WATCHDOG_INTERRUPT		(1 <<  6) /* gen8+ */
>   #define GT_RENDER_L3_PARITY_ERROR_INTERRUPT	(1 <<  5) /* !snb */
>   #define GT_RENDER_PIPECTL_NOTIFY_INTERRUPT	(1 <<  4)
>   #define GT_RENDER_CS_MASTER_ERROR_INTERRUPT	(1 <<  3)
> diff --git a/drivers/gpu/drm/i915/i915_reset.c b/drivers/gpu/drm/i915/i915_reset.c
> index 861fe083e383..739fa5ad1a8d 100644
> --- a/drivers/gpu/drm/i915/i915_reset.c
> +++ b/drivers/gpu/drm/i915/i915_reset.c
> @@ -1208,6 +1208,26 @@ void i915_clear_error_registers(struct drm_i915_private *dev_priv)
>   	}
>   }
>   
> +void engine_reset_error_to_str(struct drm_i915_private *i915,
> +	           char *msg,
> +	           size_t sz,
> +	           unsigned int hung,
> +	           unsigned int stuck,
> +	           unsigned int watchdog)
> +{
> +	int len;
> +	unsigned int tmp;
> +	struct intel_engine_cs *engine;
> +
> +	len = scnprintf(msg, sz,
> +			"%s on ", watchdog ? "watchdog timeout" :
> +				stuck == hung ? "no_progress" : "hang");
> +	for_each_engine_masked(engine, i915, hung, tmp)
> +		len += scnprintf(msg + len, sz - len,
> +				"%s, ", engine->name);
> +	msg[len-2] = '\0';
> +}
> +
>   /**
>    * i915_handle_error - handle a gpu error
>    * @i915: i915 device private
> diff --git a/drivers/gpu/drm/i915/i915_reset.h b/drivers/gpu/drm/i915/i915_reset.h
> index 16f2389f656f..8582d1242248 100644
> --- a/drivers/gpu/drm/i915/i915_reset.h
> +++ b/drivers/gpu/drm/i915/i915_reset.h
> @@ -20,6 +20,12 @@ void i915_handle_error(struct drm_i915_private *i915,
>   		       u32 engine_mask,
>   		       unsigned long flags,
>   		       const char *fmt, ...);
> +void engine_reset_error_to_str(struct drm_i915_private *i915,
> +               char *str,
> +               size_t sz,
> +               unsigned int hung,
> +               unsigned int stuck,
> +               unsigned int watchdog);
>   #define I915_ERROR_CAPTURE BIT(0)
>   
>   void i915_clear_error_registers(struct drm_i915_private *i915);
> diff --git a/drivers/gpu/drm/i915/intel_engine_cs.c b/drivers/gpu/drm/i915/intel_engine_cs.c
> index 652c1b3ba190..88cf0fc07623 100644
> --- a/drivers/gpu/drm/i915/intel_engine_cs.c
> +++ b/drivers/gpu/drm/i915/intel_engine_cs.c
> @@ -1149,6 +1149,7 @@ void intel_engines_park(struct drm_i915_private *i915)
>   		/* Flush the residual irq tasklets first. */
>   		intel_engine_disarm_breadcrumbs(engine);
>   		tasklet_kill(&engine->execlists.tasklet);
> +		tasklet_kill(&engine->execlists.watchdog_tasklet);
>   
>   		/*
>   		 * We are committed now to parking the engines, make sure there
> diff --git a/drivers/gpu/drm/i915/intel_engine_types.h b/drivers/gpu/drm/i915/intel_engine_types.h
> index b0aa1f0d4e47..c4f66b774e7c 100644
> --- a/drivers/gpu/drm/i915/intel_engine_types.h
> +++ b/drivers/gpu/drm/i915/intel_engine_types.h
> @@ -124,6 +124,11 @@ struct intel_engine_execlists {
>   	 */
>   	struct tasklet_struct tasklet;
>   
> +	/*
> +	 * @watchdog_tasklet: stop counter and reschedule hangcheck_work asap
> +	 */
> +	struct tasklet_struct watchdog_tasklet;
> +
>   	/**
>   	 * @default_priolist: priority list for I915_PRIORITY_NORMAL
>   	 */
> diff --git a/drivers/gpu/drm/i915/intel_hangcheck.c b/drivers/gpu/drm/i915/intel_hangcheck.c
> index 57ed49dc19c4..4bf26863678c 100644
> --- a/drivers/gpu/drm/i915/intel_hangcheck.c
> +++ b/drivers/gpu/drm/i915/intel_hangcheck.c
> @@ -220,22 +220,15 @@ static void hangcheck_declare_hang(struct drm_i915_private *i915,
>   				   unsigned int hung,
>   				   unsigned int stuck)
>   {
> -	struct intel_engine_cs *engine;
>   	char msg[80];
> -	unsigned int tmp;
> -	int len;
> +	size_t len = sizeof(msg);
>   
>   	/* If some rings hung but others were still busy, only
>   	 * blame the hanging rings in the synopsis.
>   	 */
>   	if (stuck != hung)
>   		hung &= ~stuck;
> -	len = scnprintf(msg, sizeof(msg),
> -			"%s on ", stuck == hung ? "no progress" : "hang");
> -	for_each_engine_masked(engine, i915, hung, tmp)
> -		len += scnprintf(msg + len, sizeof(msg) - len,
> -				 "%s, ", engine->name);
> -	msg[len-2] = '\0';
> +	engine_reset_error_to_str(i915, msg, len, hung, stuck, 0);
>   
>   	return i915_handle_error(i915, hung, I915_ERROR_CAPTURE, "%s", msg);
>   }
> diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
> index e54e0064b2d6..85785a94f6ae 100644
> --- a/drivers/gpu/drm/i915/intel_lrc.c
> +++ b/drivers/gpu/drm/i915/intel_lrc.c
> @@ -2195,6 +2195,40 @@ static int gen8_emit_flush_render(struct i915_request *request,
>   	return 0;
>   }
>   
> +static void gen8_watchdog_tasklet(unsigned long data)
> +{
> +	struct intel_engine_cs *engine = (struct intel_engine_cs *)data;
> +	struct drm_i915_private *dev_priv = engine->i915;
> +	enum forcewake_domains fw_domains;
> +	char msg[80];
> +	size_t len = sizeof(msg);
> +	unsigned long *lock = &engine->i915->gpu_error.flags;
> +	unsigned int bit = I915_RESET_ENGINE + engine->id;
> +
> +	switch (engine->class) {
> +	default:
> +		MISSING_CASE(engine->id);
> +		/* fall through */
> +	case RENDER_CLASS:
> +		fw_domains = FORCEWAKE_RENDER;
> +		break;
> +	case VIDEO_DECODE_CLASS:
> +	case VIDEO_ENHANCEMENT_CLASS:
> +		fw_domains = FORCEWAKE_MEDIA;
> +		break;
> +	}
> +
> +	intel_uncore_forcewake_get(dev_priv, fw_domains);
> +
> +	if (!test_and_set_bit(bit, lock)) {
> +		unsigned int hung = engine->mask;
> +		engine_reset_error_to_str(dev_priv, msg, len, hung, 0, 1);
> +		i915_reset_engine(engine, msg);
> +		clear_bit(bit, lock);
> +		wake_up_bit(lock, bit);
> +	}
> +}
> +
>   /*
>    * Reserve space for 2 NOOPs at the end of each request to be
>    * used as a workaround for not being allowed to do lite
> @@ -2377,6 +2411,21 @@ logical_ring_default_irqs(struct intel_engine_cs *engine)
>   
>   	engine->irq_enable_mask = GT_RENDER_USER_INTERRUPT << shift;
>   	engine->irq_keep_mask = GT_CONTEXT_SWITCH_INTERRUPT << shift;
> +
> +	switch (engine->class) {
> +	default:
> +		/* BCS engine does not support hw watchdog */
> +		break;
> +	case RENDER_CLASS:
> +	case VIDEO_DECODE_CLASS:
> +		engine->irq_keep_mask |= GT_GEN8_WATCHDOG_INTERRUPT << shift;
> +		break;
> +	case VIDEO_ENHANCEMENT_CLASS:
> +		if (INTEL_GEN(engine->i915) >= 9)
> +			engine->irq_keep_mask |=
> +				GT_GEN8_WATCHDOG_INTERRUPT << shift;
> +		break;
> +	}
>   }
>   
>   static int
> @@ -2394,6 +2443,9 @@ logical_ring_setup(struct intel_engine_cs *engine)
>   	tasklet_init(&engine->execlists.tasklet,
>   		     execlists_submission_tasklet, (unsigned long)engine);
>   
> +	tasklet_init(&engine->execlists.watchdog_tasklet,
> +		     gen8_watchdog_tasklet, (unsigned long)engine);
> +
>   	logical_ring_default_vfuncs(engine);
>   	logical_ring_default_irqs(engine);
>   
>
Santa, Carlos March 27, 2019, 1:58 a.m. UTC | #2
On Mon, 2019-03-25 at 10:00 +0000, Tvrtko Ursulin wrote:
> On 22/03/2019 23:41, Carlos Santa wrote:
> > From: Michel Thierry <michel.thierry@intel.com>
> > 
> > *** General ***
> > 
> > Watchdog timeout (or "media engine reset") is a feature that allows
> > userland applications to enable hang detection on individual batch
> > buffers.
> > The detection mechanism itself is mostly bound to the hardware and
> > the only
> > thing that the driver needs to do to support this form of hang
> > detection
> > is to implement the interrupt handling support as well as watchdog
> > command
> > emission before and after the emitted batch buffer start
> > instruction in the
> > ring buffer.
> > 
> > The principle of the hang detection mechanism is as follows:
> > 
> > 1. Once the decision has been made to enable watchdog timeout for a
> > particular batch buffer and the driver is in the process of
> > emitting the
> > batch buffer start instruction into the ring buffer it also emits a
> > watchdog timer start instruction before and a watchdog timer
> > cancellation
> > instruction after the batch buffer start instruction in the ring
> > buffer.
> > 
> > 2. Once the GPU execution reaches the watchdog timer start
> > instruction
> > the hardware watchdog counter is started by the hardware. The
> > counter
> > keeps counting until either reaching a previously configured
> > threshold
> > value or the timer cancellation instruction is executed.
> > 
> > 2a. If the counter reaches the threshold value the hardware fires a
> > watchdog interrupt that is picked up by the watchdog interrupt
> > handler.
> > This means that a hang has been detected and the driver needs to
> > deal with
> > it the same way it would deal with a engine hang detected by the
> > periodic
> > hang checker. The only difference between the two is that we
> > already blamed
> > the active request (to ensure an engine reset).
> > 
> > 2b. If the batch buffer completes and the execution reaches the
> > watchdog
> > cancellation instruction before the watchdog counter reaches its
> > threshold value the watchdog is cancelled and nothing more comes of
> > it.
> > No hang is detected.
> > 
> > Note about future interaction with preemption: Preemption could
> > happen
> > in a command sequence prior to watchdog counter getting disabled,
> > resulting in watchdog being triggered following preemption (e.g.
> > when
> > watchdog had been enabled in the low priority batch). The driver
> > will
> > need to explicitly disable the watchdog counter as part of the
> > preemption sequence.
> > 
> > *** This patch introduces: ***
> > 
> > 1. IRQ handler code for watchdog timeout allowing direct hang
> > recovery
> > based on hardware-driven hang detection, which then integrates
> > directly
> > with the hang recovery path. This is independent of having per-
> > engine reset
> > or just full gpu reset.
> > 
> > 2. Watchdog specific register information.
> > 
> > Currently the render engine and all available media engines support
> > watchdog timeout (VECS is only supported in GEN9). The
> > specifications elude
> > to the BCS engine being supported but that is currently not
> > supported by
> > this commit.
> > 
> > Note that the value to stop the counter is different between render
> > and
> > non-render engines in GEN8; GEN9 onwards it's the same.
> > 
> > v2: Move irq handler to tasklet, arm watchdog for a 2nd time to
> > check
> > against false-positives.
> > 
> > v3: Don't use high priority tasklet, use engine_last_submit while
> > checking for false-positives. From GEN9 onwards, the stop counter
> > bit is
> > the same for all engines.
> > 
> > v4: Remove unnecessary brackets, use current_seqno to mark the
> > request
> > as guilty in the hangcheck/capture code.
> > 
> > v5: Rebased after RESET_ENGINEs flag.
> > 
> > v6: Don't capture error state in case of watchdog timeout. The
> > capture
> > process is time consuming and this will align to what happens when
> > we
> > use GuC to handle the watchdog timeout. (Chris)
> > 
> > v7: Rebase.
> > 
> > v8: Rebase, use HZ to reschedule.
> > 
> > v9: Rebase, get forcewake domains in function (no longer in
> > execlists
> > struct).
> > 
> > v10: Rebase.
> > 
> > v11: Rebase,
> >       remove extra braces (Tvrtko),
> >       implement watchdog_to_clock_counts helper (Tvrtko),
> >       Move tasklet_kill(watchdog_tasklet) inside intel_engines
> > (Tvrtko),
> >       Use a global heartbeat seqno instead of engine seqno (Chris)
> >       Make all engines checks all class based checks (Tvrtko)
> > 
> > v12: Rebase,
> >       Reset immediately upon entering the IRQ (Chris)
> >       Make reset_engine_to_str a helper (Tvrtko)
> >       Rename watchdog_irq_handler as watchdog_tasklet (Tvrtko)
> >       Let the compiler itself do the inline (Tvrtko)
> > 
> > v13: Rebase
> > v14: Rebase, skip checking for the guilty seqno in the tasklet
> > (Tvrtko)
> 
> IIRC I only asked about it so I guess you tried it and it works well?
> 
> Can you also post the IGTs so we can see the test coverage?
> 
> Regards,
> 
> Tvrtko

Yeah, the unit test works but it's still the very simple one (updated
for the uAPI mods) I started with last August, I still need to add more
to it though...


https://lists.freedesktop.org/archives/igt-dev/2018-September/005834.html

Right now, I am on the hrtimer workaround to see how that works, will
get back to the test coverage after that...

Regards,
Carlos

> 
> > 
> > Cc: Antonio Argenziano <antonio.argenziano@intel.com>
> > Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
> > Signed-off-by: Michel Thierry <michel.thierry@intel.com>
> > Signed-off-by: Carlos Santa <carlos.santa@intel.com>
> > ---
> >   drivers/gpu/drm/i915/i915_gpu_error.h     |  4 ++
> >   drivers/gpu/drm/i915/i915_irq.c           | 14 ++++--
> >   drivers/gpu/drm/i915/i915_reg.h           |  6 +++
> >   drivers/gpu/drm/i915/i915_reset.c         | 20 +++++++++
> >   drivers/gpu/drm/i915/i915_reset.h         |  6 +++
> >   drivers/gpu/drm/i915/intel_engine_cs.c    |  1 +
> >   drivers/gpu/drm/i915/intel_engine_types.h |  5 +++
> >   drivers/gpu/drm/i915/intel_hangcheck.c    | 11 +----
> >   drivers/gpu/drm/i915/intel_lrc.c          | 52
> > +++++++++++++++++++++++
> >   9 files changed, 107 insertions(+), 12 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/i915_gpu_error.h
> > b/drivers/gpu/drm/i915/i915_gpu_error.h
> > index 99d6b7b270c2..6cf6a8679b26 100644
> > --- a/drivers/gpu/drm/i915/i915_gpu_error.h
> > +++ b/drivers/gpu/drm/i915/i915_gpu_error.h
> > @@ -203,6 +203,9 @@ struct i915_gpu_error {
> >   	 * any global resources that may be clobber by the reset (such
> > as
> >   	 * FENCE registers).
> >   	 *
> > +	 * #I915_RESET_WATCHDOG - When hw detects a hang before us, we
> > can use
> > +	 * I915_RESET_WATCHDOG to report the hang detection cause
> > accurately.
> > +	 *
> >   	 * #I915_RESET_ENGINE[num_engines] - Since the driver doesn't
> > need to
> >   	 * acquire the struct_mutex to reset an engine, we need an
> > explicit
> >   	 * flag to prevent two concurrent reset attempts in the same
> > engine.
> > @@ -218,6 +221,7 @@ struct i915_gpu_error {
> >   #define I915_RESET_BACKOFF	0
> >   #define I915_RESET_MODESET	1
> >   #define I915_RESET_ENGINE	2
> > +#define I915_RESET_WATCHDOG	3
> >   #define I915_WEDGED		(BITS_PER_LONG - 1)
> >   
> >   	/** Number of times the device has been reset (global) */
> > diff --git a/drivers/gpu/drm/i915/i915_irq.c
> > b/drivers/gpu/drm/i915/i915_irq.c
> > index 82d487189a34..e64994be25c3 100644
> > --- a/drivers/gpu/drm/i915/i915_irq.c
> > +++ b/drivers/gpu/drm/i915/i915_irq.c
> > @@ -1466,6 +1466,9 @@ gen8_cs_irq_handler(struct intel_engine_cs
> > *engine, u32 iir)
> >   
> >   	if (tasklet)
> >   		tasklet_hi_schedule(&engine->execlists.tasklet);
> > +
> > +	if (iir & GT_GEN8_WATCHDOG_INTERRUPT)
> > +		tasklet_schedule(&engine->execlists.watchdog_tasklet);
> >   }
> >   
> >   static void gen8_gt_irq_ack(struct drm_i915_private *i915,
> > @@ -3892,20 +3895,25 @@ static void gen8_gt_irq_postinstall(struct
> > drm_i915_private *dev_priv)
> >   	u32 gt_interrupts[] = {
> >   		(GT_RENDER_USER_INTERRUPT << GEN8_RCS_IRQ_SHIFT |
> >   		 GT_CONTEXT_SWITCH_INTERRUPT << GEN8_RCS_IRQ_SHIFT |
> > +		 GT_GEN8_WATCHDOG_INTERRUPT << GEN8_RCS_IRQ_SHIFT |
> >   		 GT_RENDER_USER_INTERRUPT << GEN8_BCS_IRQ_SHIFT |
> >   		 GT_CONTEXT_SWITCH_INTERRUPT << GEN8_BCS_IRQ_SHIFT),
> > -
> >   		(GT_RENDER_USER_INTERRUPT << GEN8_VCS0_IRQ_SHIFT |
> >   		 GT_CONTEXT_SWITCH_INTERRUPT << GEN8_VCS0_IRQ_SHIFT |
> > +		 GT_GEN8_WATCHDOG_INTERRUPT << GEN8_VCS0_IRQ_SHIFT |
> >   		 GT_RENDER_USER_INTERRUPT << GEN8_VCS1_IRQ_SHIFT |
> > -		 GT_CONTEXT_SWITCH_INTERRUPT << GEN8_VCS1_IRQ_SHIFT),
> > -
> > +		 GT_CONTEXT_SWITCH_INTERRUPT << GEN8_VCS1_IRQ_SHIFT |
> > +		 GT_GEN8_WATCHDOG_INTERRUPT << GEN8_VCS1_IRQ_SHIFT),
> >   		0,
> >   
> >   		(GT_RENDER_USER_INTERRUPT << GEN8_VECS_IRQ_SHIFT |
> >   		 GT_CONTEXT_SWITCH_INTERRUPT << GEN8_VECS_IRQ_SHIFT)
> >   	};
> >   
> > +	/* VECS watchdog is only available in skl+ */
> > +	if (INTEL_GEN(dev_priv) >= 9)
> > +		gt_interrupts[3] |= GT_GEN8_WATCHDOG_INTERRUPT;
> > +
> >   	dev_priv->pm_ier = 0x0;
> >   	dev_priv->pm_imr = ~dev_priv->pm_ier;
> >   	GEN8_IRQ_INIT_NDX(GT, 0, ~gt_interrupts[0], gt_interrupts[0]);
> > diff --git a/drivers/gpu/drm/i915/i915_reg.h
> > b/drivers/gpu/drm/i915/i915_reg.h
> > index 9b69cec21f7b..ac8d984e16ae 100644
> > --- a/drivers/gpu/drm/i915/i915_reg.h
> > +++ b/drivers/gpu/drm/i915/i915_reg.h
> > @@ -2363,6 +2363,11 @@ enum i915_power_well_id {
> >   #define RING_START(base)	_MMIO((base) + 0x38)
> >   #define RING_CTL(base)		_MMIO((base) + 0x3c)
> >   #define   RING_CTL_SIZE(size)	((size) - PAGE_SIZE) /* in
> > bytes -> pages */
> > +#define RING_CNTR(base)		_MMIO((base) + 0x178)
> > +#define GEN8_WATCHDOG_ENABLE		0
> > +#define GEN8_WATCHDOG_DISABLE		1
> > +#define GEN8_XCS_WATCHDOG_DISABLE	0xFFFFFFFF /* GEN8 & non-render 
> > only */
> > +#define RING_THRESH(base)	_MMIO((base) + 0x17C)
> >   #define RING_SYNC_0(base)	_MMIO((base) + 0x40)
> >   #define RING_SYNC_1(base)	_MMIO((base) + 0x44)
> >   #define RING_SYNC_2(base)	_MMIO((base) + 0x48)
> > @@ -2925,6 +2930,7 @@ enum i915_power_well_id {
> >   #define GT_BSD_USER_INTERRUPT			(1 << 12)
> >   #define GT_RENDER_L3_PARITY_ERROR_INTERRUPT_S1	(1 << 11) /*
> > hsw+; rsvd on snb, ivb, vlv */
> >   #define GT_CONTEXT_SWITCH_INTERRUPT		(1 <<  8)
> > +#define GT_GEN8_WATCHDOG_INTERRUPT		(1 <<  6) /* gen8+ */
> >   #define GT_RENDER_L3_PARITY_ERROR_INTERRUPT	(1 <<  5) /*
> > !snb */
> >   #define GT_RENDER_PIPECTL_NOTIFY_INTERRUPT	(1 <<  4)
> >   #define GT_RENDER_CS_MASTER_ERROR_INTERRUPT	(1 <<  3)
> > diff --git a/drivers/gpu/drm/i915/i915_reset.c
> > b/drivers/gpu/drm/i915/i915_reset.c
> > index 861fe083e383..739fa5ad1a8d 100644
> > --- a/drivers/gpu/drm/i915/i915_reset.c
> > +++ b/drivers/gpu/drm/i915/i915_reset.c
> > @@ -1208,6 +1208,26 @@ void i915_clear_error_registers(struct
> > drm_i915_private *dev_priv)
> >   	}
> >   }
> >   
> > +void engine_reset_error_to_str(struct drm_i915_private *i915,
> > +	           char *msg,
> > +	           size_t sz,
> > +	           unsigned int hung,
> > +	           unsigned int stuck,
> > +	           unsigned int watchdog)
> > +{
> > +	int len;
> > +	unsigned int tmp;
> > +	struct intel_engine_cs *engine;
> > +
> > +	len = scnprintf(msg, sz,
> > +			"%s on ", watchdog ? "watchdog timeout" :
> > +				stuck == hung ? "no_progress" :
> > "hang");
> > +	for_each_engine_masked(engine, i915, hung, tmp)
> > +		len += scnprintf(msg + len, sz - len,
> > +				"%s, ", engine->name);
> > +	msg[len-2] = '\0';
> > +}
> > +
> >   /**
> >    * i915_handle_error - handle a gpu error
> >    * @i915: i915 device private
> > diff --git a/drivers/gpu/drm/i915/i915_reset.h
> > b/drivers/gpu/drm/i915/i915_reset.h
> > index 16f2389f656f..8582d1242248 100644
> > --- a/drivers/gpu/drm/i915/i915_reset.h
> > +++ b/drivers/gpu/drm/i915/i915_reset.h
> > @@ -20,6 +20,12 @@ void i915_handle_error(struct drm_i915_private
> > *i915,
> >   		       u32 engine_mask,
> >   		       unsigned long flags,
> >   		       const char *fmt, ...);
> > +void engine_reset_error_to_str(struct drm_i915_private *i915,
> > +               char *str,
> > +               size_t sz,
> > +               unsigned int hung,
> > +               unsigned int stuck,
> > +               unsigned int watchdog);
> >   #define I915_ERROR_CAPTURE BIT(0)
> >   
> >   void i915_clear_error_registers(struct drm_i915_private *i915);
> > diff --git a/drivers/gpu/drm/i915/intel_engine_cs.c
> > b/drivers/gpu/drm/i915/intel_engine_cs.c
> > index 652c1b3ba190..88cf0fc07623 100644
> > --- a/drivers/gpu/drm/i915/intel_engine_cs.c
> > +++ b/drivers/gpu/drm/i915/intel_engine_cs.c
> > @@ -1149,6 +1149,7 @@ void intel_engines_park(struct
> > drm_i915_private *i915)
> >   		/* Flush the residual irq tasklets first. */
> >   		intel_engine_disarm_breadcrumbs(engine);
> >   		tasklet_kill(&engine->execlists.tasklet);
> > +		tasklet_kill(&engine->execlists.watchdog_tasklet);
> >   
> >   		/*
> >   		 * We are committed now to parking the engines, make
> > sure there
> > diff --git a/drivers/gpu/drm/i915/intel_engine_types.h
> > b/drivers/gpu/drm/i915/intel_engine_types.h
> > index b0aa1f0d4e47..c4f66b774e7c 100644
> > --- a/drivers/gpu/drm/i915/intel_engine_types.h
> > +++ b/drivers/gpu/drm/i915/intel_engine_types.h
> > @@ -124,6 +124,11 @@ struct intel_engine_execlists {
> >   	 */
> >   	struct tasklet_struct tasklet;
> >   
> > +	/*
> > +	 * @watchdog_tasklet: stop counter and reschedule
> > hangcheck_work asap
> > +	 */
> > +	struct tasklet_struct watchdog_tasklet;
> > +
> >   	/**
> >   	 * @default_priolist: priority list for I915_PRIORITY_NORMAL
> >   	 */
> > diff --git a/drivers/gpu/drm/i915/intel_hangcheck.c
> > b/drivers/gpu/drm/i915/intel_hangcheck.c
> > index 57ed49dc19c4..4bf26863678c 100644
> > --- a/drivers/gpu/drm/i915/intel_hangcheck.c
> > +++ b/drivers/gpu/drm/i915/intel_hangcheck.c
> > @@ -220,22 +220,15 @@ static void hangcheck_declare_hang(struct
> > drm_i915_private *i915,
> >   				   unsigned int hung,
> >   				   unsigned int stuck)
> >   {
> > -	struct intel_engine_cs *engine;
> >   	char msg[80];
> > -	unsigned int tmp;
> > -	int len;
> > +	size_t len = sizeof(msg);
> >   
> >   	/* If some rings hung but others were still busy, only
> >   	 * blame the hanging rings in the synopsis.
> >   	 */
> >   	if (stuck != hung)
> >   		hung &= ~stuck;
> > -	len = scnprintf(msg, sizeof(msg),
> > -			"%s on ", stuck == hung ? "no progress" :
> > "hang");
> > -	for_each_engine_masked(engine, i915, hung, tmp)
> > -		len += scnprintf(msg + len, sizeof(msg) - len,
> > -				 "%s, ", engine->name);
> > -	msg[len-2] = '\0';
> > +	engine_reset_error_to_str(i915, msg, len, hung, stuck, 0);
> >   
> >   	return i915_handle_error(i915, hung, I915_ERROR_CAPTURE, "%s",
> > msg);
> >   }
> > diff --git a/drivers/gpu/drm/i915/intel_lrc.c
> > b/drivers/gpu/drm/i915/intel_lrc.c
> > index e54e0064b2d6..85785a94f6ae 100644
> > --- a/drivers/gpu/drm/i915/intel_lrc.c
> > +++ b/drivers/gpu/drm/i915/intel_lrc.c
> > @@ -2195,6 +2195,40 @@ static int gen8_emit_flush_render(struct
> > i915_request *request,
> >   	return 0;
> >   }
> >   
> > +static void gen8_watchdog_tasklet(unsigned long data)
> > +{
> > +	struct intel_engine_cs *engine = (struct intel_engine_cs
> > *)data;
> > +	struct drm_i915_private *dev_priv = engine->i915;
> > +	enum forcewake_domains fw_domains;
> > +	char msg[80];
> > +	size_t len = sizeof(msg);
> > +	unsigned long *lock = &engine->i915->gpu_error.flags;
> > +	unsigned int bit = I915_RESET_ENGINE + engine->id;
> > +
> > +	switch (engine->class) {
> > +	default:
> > +		MISSING_CASE(engine->id);
> > +		/* fall through */
> > +	case RENDER_CLASS:
> > +		fw_domains = FORCEWAKE_RENDER;
> > +		break;
> > +	case VIDEO_DECODE_CLASS:
> > +	case VIDEO_ENHANCEMENT_CLASS:
> > +		fw_domains = FORCEWAKE_MEDIA;
> > +		break;
> > +	}
> > +
> > +	intel_uncore_forcewake_get(dev_priv, fw_domains);
> > +
> > +	if (!test_and_set_bit(bit, lock)) {
> > +		unsigned int hung = engine->mask;
> > +		engine_reset_error_to_str(dev_priv, msg, len, hung, 0,
> > 1);
> > +		i915_reset_engine(engine, msg);
> > +		clear_bit(bit, lock);
> > +		wake_up_bit(lock, bit);
> > +	}
> > +}
> > +
> >   /*
> >    * Reserve space for 2 NOOPs at the end of each request to be
> >    * used as a workaround for not being allowed to do lite
> > @@ -2377,6 +2411,21 @@ logical_ring_default_irqs(struct
> > intel_engine_cs *engine)
> >   
> >   	engine->irq_enable_mask = GT_RENDER_USER_INTERRUPT << shift;
> >   	engine->irq_keep_mask = GT_CONTEXT_SWITCH_INTERRUPT << shift;
> > +
> > +	switch (engine->class) {
> > +	default:
> > +		/* BCS engine does not support hw watchdog */
> > +		break;
> > +	case RENDER_CLASS:
> > +	case VIDEO_DECODE_CLASS:
> > +		engine->irq_keep_mask |= GT_GEN8_WATCHDOG_INTERRUPT <<
> > shift;
> > +		break;
> > +	case VIDEO_ENHANCEMENT_CLASS:
> > +		if (INTEL_GEN(engine->i915) >= 9)
> > +			engine->irq_keep_mask |=
> > +				GT_GEN8_WATCHDOG_INTERRUPT << shift;
> > +		break;
> > +	}
> >   }
> >   
> >   static int
> > @@ -2394,6 +2443,9 @@ logical_ring_setup(struct intel_engine_cs
> > *engine)
> >   	tasklet_init(&engine->execlists.tasklet,
> >   		     execlists_submission_tasklet, (unsigned
> > long)engine);
> >   
> > +	tasklet_init(&engine->execlists.watchdog_tasklet,
> > +		     gen8_watchdog_tasklet, (unsigned long)engine);
> > +
> >   	logical_ring_default_vfuncs(engine);
> >   	logical_ring_default_irqs(engine);
> >   
> >
Tvrtko Ursulin March 27, 2019, 10:40 a.m. UTC | #3
On 27/03/2019 01:58, Carlos Santa wrote:

[snip]

>>> v13: Rebase
>>> v14: Rebase, skip checking for the guilty seqno in the tasklet
>>> (Tvrtko)
>>
>> IIRC I only asked about it so I guess you tried it and it works well?
>>
>> Can you also post the IGTs so we can see the test coverage?
>>
>> Regards,
>>
>> Tvrtko
> 
> Yeah, the unit test works but it's still the very simple one (updated
> for the uAPI mods) I started with last August, I still need to add more
> to it though...
> 
> 
> https://lists.freedesktop.org/archives/igt-dev/2018-September/005834.html
> 
> Right now, I am on the hrtimer workaround to see how that works, will
> get back to the test coverage after that...

It may be tricky though so it may make sense to extend the test first 
until you can make a test which fails with the hw watchdog 
implementation. :)

What are the test cases I can think of..

Probably could use fence status to figure out which context was reset, 
and could use spin batches with userspace timers to control durations. 
And corking to control ordering. Then you need some preemption 
(priorities). A mix of batches on contexts with and without the watchdog 
and checking the expected one was reset.

ctx = create_context

long batch -> executed

ctx.set_watchdog

ctx.long batch -> canceled

ctx2.long_batch
ctx.long_batch

  -> executed, canceled

ctx.long_batch
ctx2.long_batch

  -> canceled, executed

(Hm maybe you end up having to use nop calibrated batches to make the 
last one work.)

ctx.batch_just_below_threshold -> executed

(Try a few times in a loop, or a bunch of batches like this one 
submitted at once and check all executed.)

Then expand and submit one random one of them as over threshold and 
check only that one was canceled.

Flavour of the above with two contexts, one with watchdog, one without.

Flavour where watchdog is set only on some engines. Single context, 
batches on different engines = different watchog behaviour.

Then preemption handling.. submit a long batch and after half of 
expected runtime submit a higher prio batch with half duration. Check 
the latter was executed. Then check the status of the former. What 
should it be? (Don't know, open to define the semantics..)

Submit a low prio long batch, wo/ watchdog, then a higher prio with 
watchdog and check it was canceled before the low prio one completed.

This is how much I can think of right now, but should be a good start.

Regards,

Tvrtko
diff mbox series

Patch

diff --git a/drivers/gpu/drm/i915/i915_gpu_error.h b/drivers/gpu/drm/i915/i915_gpu_error.h
index 99d6b7b270c2..6cf6a8679b26 100644
--- a/drivers/gpu/drm/i915/i915_gpu_error.h
+++ b/drivers/gpu/drm/i915/i915_gpu_error.h
@@ -203,6 +203,9 @@  struct i915_gpu_error {
 	 * any global resources that may be clobber by the reset (such as
 	 * FENCE registers).
 	 *
+	 * #I915_RESET_WATCHDOG - When hw detects a hang before us, we can use
+	 * I915_RESET_WATCHDOG to report the hang detection cause accurately.
+	 *
 	 * #I915_RESET_ENGINE[num_engines] - Since the driver doesn't need to
 	 * acquire the struct_mutex to reset an engine, we need an explicit
 	 * flag to prevent two concurrent reset attempts in the same engine.
@@ -218,6 +221,7 @@  struct i915_gpu_error {
 #define I915_RESET_BACKOFF	0
 #define I915_RESET_MODESET	1
 #define I915_RESET_ENGINE	2
+#define I915_RESET_WATCHDOG	3
 #define I915_WEDGED		(BITS_PER_LONG - 1)
 
 	/** Number of times the device has been reset (global) */
diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index 82d487189a34..e64994be25c3 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -1466,6 +1466,9 @@  gen8_cs_irq_handler(struct intel_engine_cs *engine, u32 iir)
 
 	if (tasklet)
 		tasklet_hi_schedule(&engine->execlists.tasklet);
+
+	if (iir & GT_GEN8_WATCHDOG_INTERRUPT)
+		tasklet_schedule(&engine->execlists.watchdog_tasklet);
 }
 
 static void gen8_gt_irq_ack(struct drm_i915_private *i915,
@@ -3892,20 +3895,25 @@  static void gen8_gt_irq_postinstall(struct drm_i915_private *dev_priv)
 	u32 gt_interrupts[] = {
 		(GT_RENDER_USER_INTERRUPT << GEN8_RCS_IRQ_SHIFT |
 		 GT_CONTEXT_SWITCH_INTERRUPT << GEN8_RCS_IRQ_SHIFT |
+		 GT_GEN8_WATCHDOG_INTERRUPT << GEN8_RCS_IRQ_SHIFT |
 		 GT_RENDER_USER_INTERRUPT << GEN8_BCS_IRQ_SHIFT |
 		 GT_CONTEXT_SWITCH_INTERRUPT << GEN8_BCS_IRQ_SHIFT),
-
 		(GT_RENDER_USER_INTERRUPT << GEN8_VCS0_IRQ_SHIFT |
 		 GT_CONTEXT_SWITCH_INTERRUPT << GEN8_VCS0_IRQ_SHIFT |
+		 GT_GEN8_WATCHDOG_INTERRUPT << GEN8_VCS0_IRQ_SHIFT |
 		 GT_RENDER_USER_INTERRUPT << GEN8_VCS1_IRQ_SHIFT |
-		 GT_CONTEXT_SWITCH_INTERRUPT << GEN8_VCS1_IRQ_SHIFT),
-
+		 GT_CONTEXT_SWITCH_INTERRUPT << GEN8_VCS1_IRQ_SHIFT |
+		 GT_GEN8_WATCHDOG_INTERRUPT << GEN8_VCS1_IRQ_SHIFT),
 		0,
 
 		(GT_RENDER_USER_INTERRUPT << GEN8_VECS_IRQ_SHIFT |
 		 GT_CONTEXT_SWITCH_INTERRUPT << GEN8_VECS_IRQ_SHIFT)
 	};
 
+	/* VECS watchdog is only available in skl+ */
+	if (INTEL_GEN(dev_priv) >= 9)
+		gt_interrupts[3] |= GT_GEN8_WATCHDOG_INTERRUPT;
+
 	dev_priv->pm_ier = 0x0;
 	dev_priv->pm_imr = ~dev_priv->pm_ier;
 	GEN8_IRQ_INIT_NDX(GT, 0, ~gt_interrupts[0], gt_interrupts[0]);
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 9b69cec21f7b..ac8d984e16ae 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -2363,6 +2363,11 @@  enum i915_power_well_id {
 #define RING_START(base)	_MMIO((base) + 0x38)
 #define RING_CTL(base)		_MMIO((base) + 0x3c)
 #define   RING_CTL_SIZE(size)	((size) - PAGE_SIZE) /* in bytes -> pages */
+#define RING_CNTR(base)		_MMIO((base) + 0x178)
+#define GEN8_WATCHDOG_ENABLE		0
+#define GEN8_WATCHDOG_DISABLE		1
+#define GEN8_XCS_WATCHDOG_DISABLE	0xFFFFFFFF /* GEN8 & non-render only */
+#define RING_THRESH(base)	_MMIO((base) + 0x17C)
 #define RING_SYNC_0(base)	_MMIO((base) + 0x40)
 #define RING_SYNC_1(base)	_MMIO((base) + 0x44)
 #define RING_SYNC_2(base)	_MMIO((base) + 0x48)
@@ -2925,6 +2930,7 @@  enum i915_power_well_id {
 #define GT_BSD_USER_INTERRUPT			(1 << 12)
 #define GT_RENDER_L3_PARITY_ERROR_INTERRUPT_S1	(1 << 11) /* hsw+; rsvd on snb, ivb, vlv */
 #define GT_CONTEXT_SWITCH_INTERRUPT		(1 <<  8)
+#define GT_GEN8_WATCHDOG_INTERRUPT		(1 <<  6) /* gen8+ */
 #define GT_RENDER_L3_PARITY_ERROR_INTERRUPT	(1 <<  5) /* !snb */
 #define GT_RENDER_PIPECTL_NOTIFY_INTERRUPT	(1 <<  4)
 #define GT_RENDER_CS_MASTER_ERROR_INTERRUPT	(1 <<  3)
diff --git a/drivers/gpu/drm/i915/i915_reset.c b/drivers/gpu/drm/i915/i915_reset.c
index 861fe083e383..739fa5ad1a8d 100644
--- a/drivers/gpu/drm/i915/i915_reset.c
+++ b/drivers/gpu/drm/i915/i915_reset.c
@@ -1208,6 +1208,26 @@  void i915_clear_error_registers(struct drm_i915_private *dev_priv)
 	}
 }
 
+void engine_reset_error_to_str(struct drm_i915_private *i915,
+	           char *msg,
+	           size_t sz,
+	           unsigned int hung,
+	           unsigned int stuck,
+	           unsigned int watchdog)
+{
+	int len;
+	unsigned int tmp;
+	struct intel_engine_cs *engine;
+
+	len = scnprintf(msg, sz,
+			"%s on ", watchdog ? "watchdog timeout" :
+				stuck == hung ? "no_progress" : "hang");
+	for_each_engine_masked(engine, i915, hung, tmp)
+		len += scnprintf(msg + len, sz - len,
+				"%s, ", engine->name);
+	msg[len-2] = '\0';
+}
+
 /**
  * i915_handle_error - handle a gpu error
  * @i915: i915 device private
diff --git a/drivers/gpu/drm/i915/i915_reset.h b/drivers/gpu/drm/i915/i915_reset.h
index 16f2389f656f..8582d1242248 100644
--- a/drivers/gpu/drm/i915/i915_reset.h
+++ b/drivers/gpu/drm/i915/i915_reset.h
@@ -20,6 +20,12 @@  void i915_handle_error(struct drm_i915_private *i915,
 		       u32 engine_mask,
 		       unsigned long flags,
 		       const char *fmt, ...);
+void engine_reset_error_to_str(struct drm_i915_private *i915,
+               char *str,
+               size_t sz,
+               unsigned int hung,
+               unsigned int stuck,
+               unsigned int watchdog);
 #define I915_ERROR_CAPTURE BIT(0)
 
 void i915_clear_error_registers(struct drm_i915_private *i915);
diff --git a/drivers/gpu/drm/i915/intel_engine_cs.c b/drivers/gpu/drm/i915/intel_engine_cs.c
index 652c1b3ba190..88cf0fc07623 100644
--- a/drivers/gpu/drm/i915/intel_engine_cs.c
+++ b/drivers/gpu/drm/i915/intel_engine_cs.c
@@ -1149,6 +1149,7 @@  void intel_engines_park(struct drm_i915_private *i915)
 		/* Flush the residual irq tasklets first. */
 		intel_engine_disarm_breadcrumbs(engine);
 		tasklet_kill(&engine->execlists.tasklet);
+		tasklet_kill(&engine->execlists.watchdog_tasklet);
 
 		/*
 		 * We are committed now to parking the engines, make sure there
diff --git a/drivers/gpu/drm/i915/intel_engine_types.h b/drivers/gpu/drm/i915/intel_engine_types.h
index b0aa1f0d4e47..c4f66b774e7c 100644
--- a/drivers/gpu/drm/i915/intel_engine_types.h
+++ b/drivers/gpu/drm/i915/intel_engine_types.h
@@ -124,6 +124,11 @@  struct intel_engine_execlists {
 	 */
 	struct tasklet_struct tasklet;
 
+	/*
+	 * @watchdog_tasklet: stop counter and reschedule hangcheck_work asap
+	 */
+	struct tasklet_struct watchdog_tasklet;
+
 	/**
 	 * @default_priolist: priority list for I915_PRIORITY_NORMAL
 	 */
diff --git a/drivers/gpu/drm/i915/intel_hangcheck.c b/drivers/gpu/drm/i915/intel_hangcheck.c
index 57ed49dc19c4..4bf26863678c 100644
--- a/drivers/gpu/drm/i915/intel_hangcheck.c
+++ b/drivers/gpu/drm/i915/intel_hangcheck.c
@@ -220,22 +220,15 @@  static void hangcheck_declare_hang(struct drm_i915_private *i915,
 				   unsigned int hung,
 				   unsigned int stuck)
 {
-	struct intel_engine_cs *engine;
 	char msg[80];
-	unsigned int tmp;
-	int len;
+	size_t len = sizeof(msg);
 
 	/* If some rings hung but others were still busy, only
 	 * blame the hanging rings in the synopsis.
 	 */
 	if (stuck != hung)
 		hung &= ~stuck;
-	len = scnprintf(msg, sizeof(msg),
-			"%s on ", stuck == hung ? "no progress" : "hang");
-	for_each_engine_masked(engine, i915, hung, tmp)
-		len += scnprintf(msg + len, sizeof(msg) - len,
-				 "%s, ", engine->name);
-	msg[len-2] = '\0';
+	engine_reset_error_to_str(i915, msg, len, hung, stuck, 0);
 
 	return i915_handle_error(i915, hung, I915_ERROR_CAPTURE, "%s", msg);
 }
diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index e54e0064b2d6..85785a94f6ae 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -2195,6 +2195,40 @@  static int gen8_emit_flush_render(struct i915_request *request,
 	return 0;
 }
 
+static void gen8_watchdog_tasklet(unsigned long data)
+{
+	struct intel_engine_cs *engine = (struct intel_engine_cs *)data;
+	struct drm_i915_private *dev_priv = engine->i915;
+	enum forcewake_domains fw_domains;
+	char msg[80];
+	size_t len = sizeof(msg);
+	unsigned long *lock = &engine->i915->gpu_error.flags;
+	unsigned int bit = I915_RESET_ENGINE + engine->id;
+
+	switch (engine->class) {
+	default:
+		MISSING_CASE(engine->id);
+		/* fall through */
+	case RENDER_CLASS:
+		fw_domains = FORCEWAKE_RENDER;
+		break;
+	case VIDEO_DECODE_CLASS:
+	case VIDEO_ENHANCEMENT_CLASS:
+		fw_domains = FORCEWAKE_MEDIA;
+		break;
+	}
+
+	intel_uncore_forcewake_get(dev_priv, fw_domains);
+
+	if (!test_and_set_bit(bit, lock)) {
+		unsigned int hung = engine->mask;
+		engine_reset_error_to_str(dev_priv, msg, len, hung, 0, 1);
+		i915_reset_engine(engine, msg);
+		clear_bit(bit, lock);
+		wake_up_bit(lock, bit);
+	}
+}
+
 /*
  * Reserve space for 2 NOOPs at the end of each request to be
  * used as a workaround for not being allowed to do lite
@@ -2377,6 +2411,21 @@  logical_ring_default_irqs(struct intel_engine_cs *engine)
 
 	engine->irq_enable_mask = GT_RENDER_USER_INTERRUPT << shift;
 	engine->irq_keep_mask = GT_CONTEXT_SWITCH_INTERRUPT << shift;
+
+	switch (engine->class) {
+	default:
+		/* BCS engine does not support hw watchdog */
+		break;
+	case RENDER_CLASS:
+	case VIDEO_DECODE_CLASS:
+		engine->irq_keep_mask |= GT_GEN8_WATCHDOG_INTERRUPT << shift;
+		break;
+	case VIDEO_ENHANCEMENT_CLASS:
+		if (INTEL_GEN(engine->i915) >= 9)
+			engine->irq_keep_mask |=
+				GT_GEN8_WATCHDOG_INTERRUPT << shift;
+		break;
+	}
 }
 
 static int
@@ -2394,6 +2443,9 @@  logical_ring_setup(struct intel_engine_cs *engine)
 	tasklet_init(&engine->execlists.tasklet,
 		     execlists_submission_tasklet, (unsigned long)engine);
 
+	tasklet_init(&engine->execlists.watchdog_tasklet,
+		     gen8_watchdog_tasklet, (unsigned long)engine);
+
 	logical_ring_default_vfuncs(engine);
 	logical_ring_default_irqs(engine);