[Intel-gfx] [PATCH 41/47] drm/i915/guc: Capture error state on context reset

[Matthew Brost <matthew.brost@intel.com>]

We receive notification of an engine reset from GuC at its
completion. Meaning GuC has potentially cleared any HW state
we may have been interested in capturing. GuC resumes scheduling
on the engine post-reset, as the resets are meant to be transparent,
further muddling our error state.

There is ongoing work to define an API for a GuC debug state dump. The
suggestion for now is to manually disable FW initiated resets in cases
where debug state is needed.

Signed-off-by: Matthew Brost <matthew.brost@intel.com>
---
 drivers/gpu/drm/i915/gt/intel_context.c       | 20 +++++++++++
 drivers/gpu/drm/i915/gt/intel_context.h       |  3 ++
 drivers/gpu/drm/i915/gt/intel_engine.h        | 21 ++++++++++-
 drivers/gpu/drm/i915/gt/intel_engine_cs.c     | 11 ++++--
 drivers/gpu/drm/i915/gt/intel_engine_types.h  |  2 ++
 .../gpu/drm/i915/gt/uc/intel_guc_submission.c | 35 +++++++++----------
 drivers/gpu/drm/i915/i915_gpu_error.c         | 25 ++++++++++---
 7 files changed, 91 insertions(+), 26 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/intel_context.c b/drivers/gpu/drm/i915/gt/intel_context.c
index 2f01437056a8..3fe7794b2bfd 100644
--- a/drivers/gpu/drm/i915/gt/intel_context.c
+++ b/drivers/gpu/drm/i915/gt/intel_context.c
@@ -514,6 +514,26 @@ struct i915_request *intel_context_create_request(struct intel_context *ce)
 	return rq;
 }
 
+struct i915_request *intel_context_find_active_request(struct intel_context *ce)
+{
+	struct i915_request *rq, *active = NULL;
+	unsigned long flags;
+
+	GEM_BUG_ON(!intel_engine_uses_guc(ce->engine));
+
+	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;
+}
+
 #if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
 #include "selftest_context.c"
 #endif
diff --git a/drivers/gpu/drm/i915/gt/intel_context.h b/drivers/gpu/drm/i915/gt/intel_context.h
index a592a9605dc8..3363b59c0c40 100644
--- a/drivers/gpu/drm/i915/gt/intel_context.h
+++ b/drivers/gpu/drm/i915/gt/intel_context.h
@@ -201,6 +201,9 @@ int intel_context_prepare_remote_request(struct intel_context *ce,
 
 struct i915_request *intel_context_create_request(struct intel_context *ce);
 
+struct i915_request *
+intel_context_find_active_request(struct intel_context *ce);
+
 static inline struct intel_ring *__intel_context_ring_size(u64 sz)
 {
 	return u64_to_ptr(struct intel_ring, sz);
diff --git a/drivers/gpu/drm/i915/gt/intel_engine.h b/drivers/gpu/drm/i915/gt/intel_engine.h
index e9e0657f847a..6ea5643a3aaa 100644
--- a/drivers/gpu/drm/i915/gt/intel_engine.h
+++ b/drivers/gpu/drm/i915/gt/intel_engine.h
@@ -245,7 +245,7 @@ ktime_t intel_engine_get_busy_time(struct intel_engine_cs *engine,
 				   ktime_t *now);
 
 struct i915_request *
-intel_engine_find_active_request(struct intel_engine_cs *engine);
+intel_engine_execlist_find_hung_request(struct intel_engine_cs *engine);
 
 u32 intel_engine_context_size(struct intel_gt *gt, u8 class);
 struct intel_context *
@@ -328,4 +328,23 @@ intel_engine_get_sibling(struct intel_engine_cs *engine, unsigned int sibling)
 	return engine->cops->get_sibling(engine, sibling);
 }
 
+static inline void
+intel_engine_set_hung_context(struct intel_engine_cs *engine,
+			      struct intel_context *ce)
+{
+	engine->hung_ce = ce;
+}
+
+static inline void
+intel_engine_clear_hung_context(struct intel_engine_cs *engine)
+{
+	intel_engine_set_hung_context(engine, NULL);
+}
+
+static inline struct intel_context *
+intel_engine_get_hung_context(struct intel_engine_cs *engine)
+{
+	return engine->hung_ce;
+}
+
 #endif /* _INTEL_RINGBUFFER_H_ */
diff --git a/drivers/gpu/drm/i915/gt/intel_engine_cs.c b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
index 69245670b8b0..1d243b83b023 100644
--- a/drivers/gpu/drm/i915/gt/intel_engine_cs.c
+++ b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
@@ -1671,7 +1671,7 @@ void intel_engine_dump(struct intel_engine_cs *engine,
 	drm_printf(m, "\tRequests:\n");
 
 	spin_lock_irqsave(&engine->sched_engine->lock, flags);
-	rq = intel_engine_find_active_request(engine);
+	rq = intel_engine_execlist_find_hung_request(engine);
 	if (rq) {
 		struct intel_timeline *tl = get_timeline(rq);
 
@@ -1782,10 +1782,17 @@ static bool match_ring(struct i915_request *rq)
 }
 
 struct i915_request *
-intel_engine_find_active_request(struct intel_engine_cs *engine)
+intel_engine_execlist_find_hung_request(struct intel_engine_cs *engine)
 {
 	struct i915_request *request, *active = NULL;
 
+	/*
+	 * This search does not work in GuC submission mode. However, the GuC
+	 * will report the hanging context directly to the driver itself. So
+	 * the driver should never get here when in GuC mode.
+	 */
+	GEM_BUG_ON(intel_uc_uses_guc_submission(&engine->gt->uc));
+
 	/*
 	 * We are called by the error capture, reset and to dump engine
 	 * state at random points in time. In particular, note that neither is
diff --git a/drivers/gpu/drm/i915/gt/intel_engine_types.h b/drivers/gpu/drm/i915/gt/intel_engine_types.h
index f9d264c008e8..0ceffa2be7a7 100644
--- a/drivers/gpu/drm/i915/gt/intel_engine_types.h
+++ b/drivers/gpu/drm/i915/gt/intel_engine_types.h
@@ -303,6 +303,8 @@ struct intel_engine_cs {
 	/* keep a request in reserve for a [pm] barrier under oom */
 	struct i915_request *request_pool;
 
+	struct intel_context *hung_ce;
+
 	struct llist_head barrier_tasks;
 
 	struct intel_context *kernel_context; /* pinned */
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 c3223958dfe0..315edeaa186a 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
@@ -727,24 +727,6 @@ __unwind_incomplete_requests(struct intel_context *ce)
 	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;
@@ -758,7 +740,7 @@ static void __guc_reset_context(struct intel_context *ce, bool stalled)
 	 */
 	clr_context_enabled(ce);
 
-	rq = context_find_active_request(ce);
+	rq = intel_context_find_active_request(ce);
 	if (!rq) {
 		head = ce->ring->tail;
 		stalled = false;
@@ -2192,6 +2174,20 @@ int intel_guc_sched_done_process_msg(struct intel_guc *guc,
 	return 0;
 }
 
+static void capture_error_state(struct intel_guc *guc,
+				struct intel_context *ce)
+{
+	struct intel_gt *gt = guc_to_gt(guc);
+	struct drm_i915_private *i915 = gt->i915;
+	struct intel_engine_cs *engine = __context_to_physical_engine(ce);
+	intel_wakeref_t wakeref;
+
+	intel_engine_set_hung_context(engine, ce);
+	with_intel_runtime_pm(&i915->runtime_pm, wakeref)
+		i915_capture_error_state(gt, engine->mask);
+	atomic_inc(&i915->gpu_error.reset_engine_count[engine->uabi_class]);
+}
+
 static void guc_context_replay(struct intel_context *ce)
 {
 	struct i915_sched_engine *sched_engine = ce->engine->sched_engine;
@@ -2204,6 +2200,7 @@ static void guc_handle_context_reset(struct intel_guc *guc,
 				     struct intel_context *ce)
 {
 	trace_intel_context_reset(ce);
+	capture_error_state(guc, ce);
 	guc_context_replay(ce);
 }
 
diff --git a/drivers/gpu/drm/i915/i915_gpu_error.c b/drivers/gpu/drm/i915/i915_gpu_error.c
index cb182c6d265a..20e0a1bfadc1 100644
--- a/drivers/gpu/drm/i915/i915_gpu_error.c
+++ b/drivers/gpu/drm/i915/i915_gpu_error.c
@@ -1429,20 +1429,37 @@ capture_engine(struct intel_engine_cs *engine,
 {
 	struct intel_engine_capture_vma *capture = NULL;
 	struct intel_engine_coredump *ee;
-	struct i915_request *rq;
+	struct intel_context *ce;
+	struct i915_request *rq = NULL;
 	unsigned long flags;
 
 	ee = intel_engine_coredump_alloc(engine, GFP_KERNEL);
 	if (!ee)
 		return NULL;
 
-	spin_lock_irqsave(&engine->sched_engine->lock, flags);
-	rq = intel_engine_find_active_request(engine);
+	ce = intel_engine_get_hung_context(engine);
+	if (ce) {
+		intel_engine_clear_hung_context(engine);
+		rq = intel_context_find_active_request(ce);
+		if (!rq || !i915_request_started(rq))
+			goto no_request_capture;
+	} else {
+		/*
+		 * Getting here with GuC enabled means it is a forced error capture
+		 * with no actual hang. So, no need to attempt the execlist search.
+		 */
+		if (!intel_uc_uses_guc_submission(&engine->gt->uc)) {
+			spin_lock_irqsave(&engine->sched_engine->lock, flags);
+			rq = intel_engine_execlist_find_hung_request(engine);
+			spin_unlock_irqrestore(&engine->sched_engine->lock,
+					       flags);
+		}
+	}
 	if (rq)
 		capture = intel_engine_coredump_add_request(ee, rq,
 							    ATOMIC_MAYFAIL);
-	spin_unlock_irqrestore(&engine->sched_engine->lock, flags);
 	if (!capture) {
+no_request_capture:
 		kfree(ee);
 		return NULL;
 	}
-- 
2.28.0

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