@@ -2970,7 +2970,8 @@ static int gen8_emit_init_breadcrumb(struct i915_request *rq)
{
u32 *cs;
- GEM_BUG_ON(!i915_request_timeline(rq)->has_initial_breadcrumb);
+ if (!i915_request_timeline(rq)->has_initial_breadcrumb)
+ return 0;
cs = intel_ring_begin(rq, 6);
if (IS_ERR(cs))
@@ -4622,8 +4623,13 @@ static int __execlists_context_alloc(struct intel_context *ce,
if (!ce->timeline) {
struct intel_timeline *tl;
+ struct i915_vma *hwsp;
+
+ hwsp = NULL;
+ if (unlikely(test_bit(CONTEXT_BARRIER_BIT, &ce->flags)))
+ hwsp = engine->status_page.vma;
- tl = intel_timeline_create(engine->gt, NULL);
+ tl = intel_timeline_create(engine->gt, hwsp);
if (IS_ERR(tl)) {
ret = PTR_ERR(tl);
goto error_deref_obj;
@@ -881,11 +881,28 @@ __emit_semaphore_wait(struct i915_request *to,
return 0;
}
+static bool can_use_semaphore(const struct i915_request *rq)
+{
+ bool ok;
+
+ rcu_read_lock();
+ ok = rcu_dereference(rq->timeline)->hwsp_cacheline;
+ rcu_read_unlock();
+
+ return ok;
+}
+
static int
emit_semaphore_wait(struct i915_request *to,
struct i915_request *from,
gfp_t gfp)
{
+ if (!intel_context_use_semaphores(to->context))
+ goto await_fence;
+
+ if (!can_use_semaphore(from))
+ goto await_fence;
+
/* Just emit the first semaphore we see as request space is limited. */
if (already_busywaiting(to) & from->engine->mask)
goto await_fence;
@@ -931,12 +948,8 @@ i915_request_await_request(struct i915_request *to, struct i915_request *from)
ret = i915_sw_fence_await_sw_fence_gfp(&to->submit,
&from->submit,
I915_FENCE_GFP);
- else if (intel_context_use_semaphores(to->context))
- ret = emit_semaphore_wait(to, from, I915_FENCE_GFP);
else
- ret = i915_sw_fence_await_dma_fence(&to->submit,
- &from->fence, 0,
- I915_FENCE_GFP);
+ ret = emit_semaphore_wait(to, from, I915_FENCE_GFP);
if (ret < 0)
return ret;
Currently on execlists, we use a local hwsp for the kernel_context, rather than the engine's HWSP, as this is the default for execlists. However, seqno rollover requires allocating a new HWSP cachline, and may require pinning a new HWSP page in the GTT. This operation requiring pinning in the GGTT is not allowed within the kernel_context timeline, as doing so may require re-entering the kernel_context in order to evict from the GGTT. As we want to avoid requiring a new HWSP for the kernel_context, we can use the permanently pinned engine's HWSP instead. However to do so we must prevent the use of semaphores reading the kernel_context's HWSP, as the use of semaphores do not support rollover onto the same cacheline. Fortunately, the kernel_context is mostly isolated, so unlikely to give benefit to semaphores. Reported-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com> --- drivers/gpu/drm/i915/gt/intel_lrc.c | 10 ++++++++-- drivers/gpu/drm/i915/i915_request.c | 23 ++++++++++++++++++----- 2 files changed, 26 insertions(+), 7 deletions(-)