Re: [Intel-gfx] [RFC PATCH 74/97] drm/i915/guc: Capture error state on context reset

On Tue, May 11, 2021 at 10:12:32AM -0700, Matthew Brost wrote:

On Tue, May 11, 2021 at 06:28:25PM +0200, Daniel Vetter wrote:

...

On Thu, May 06, 2021 at 12:14:28PM -0700, Matthew Brost wrote:

...

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

This looks a bit backwards to me:

Definitely a bit hacky but this patch does the best to capture the error as it can,

...

• I figured we should capture error state when we get the G2H, in which case I hope we do know which the offending context was that got shot.

We know which context was shot based on the G2H. See 'hung_ce' in this patch.

Ah maybe I should read more. Would be good to have comments on how the locking works here, especially around reset it tends to be tricky. Comments in the data structs/members.

...

• For now we're missing the hw state, but we should still be able to capture the buffers userspace wants us to capture. So that could be wired up already?

Which buffers exactly? We dump all buffers associated with the context.

There's an opt-in list that userspace can set in execbuf. Maybe that's the one you mean. -Daniel

...

But yeah register state capturing needs support from GuC fw.

I think this is a big enough miss in GuC features that we should list it on the rfc as a thing to fix.

Agree this needs to be fixed.

Matt

...

-Daniel

...

---

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 9b211ca5ecc7..d2b499ed8a05 100644 --- a/drivers/gpu/drm/i915/gt/intel_context.h +++ b/drivers/gpu/drm/i915/gt/intel_context.h @@ -195,6 +195,9 @@ 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 3321d0917a99..bb94963a9fa2 100644 --- a/drivers/gpu/drm/i915/gt/intel_engine.h +++ b/drivers/gpu/drm/i915/gt/intel_engine.h @@ -242,7 +242,7 @@ 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);

@@ -316,4 +316,23 @@ 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 10300db1c9a6..ad3987289f09 100644 --- a/drivers/gpu/drm/i915/gt/intel_engine_cs.c +++ b/drivers/gpu/drm/i915/gt/intel_engine_cs.c @@ -1727,7 +1727,7 @@ 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);

@@ -1838,10 +1838,17 @@ 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 b84562b2708b..bba53e3b39b9 100644 --- a/drivers/gpu/drm/i915/gt/intel_engine_types.h +++ b/drivers/gpu/drm/i915/gt/intel_engine_types.h @@ -304,6 +304,8 @@ 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 22f17a055b21..6b3b74e50b31 100644 --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c @@ -726,24 +726,6 @@ __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; @@ -757,7 +739,7 @@ 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 3352f56bcf63..825bdfe44225 100644 --- a/drivers/gpu/drm/i915/i915_gpu_error.c +++ b/drivers/gpu/drm/i915/i915_gpu_error.c @@ -1435,20 +1435,37 @@ 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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-- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch