drm/i915/guc: Look for a guilty context when an engine reset fails

Engine resets are supposed to never fail. But in the case when one
does (due to unknown reasons that normally come down to a missing
w/a), it is useful to get as much information out of the system as
possible. Given that the GuC intentionally dies on such a situation,
it is not possible to get a guilty context notification back. So do a
manual search instead. Given that GuC is dead, this is safe because
GuC won't be changing the engine state asynchronously.

v2: Change comment to be less alarming (Tvrtko)

Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Acked-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230127002842.3169194-7-John.C.Harrison@Intel.com

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 a2b263e..7adc35b 100644 (file)
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
@@ -4755,11 +4755,24 @@ static void reset_fail_worker_func(struct work_struct *w)
        guc->submission_state.reset_fail_mask = 0;
        spin_unlock_irqrestore(&guc->submission_state.lock, flags);
 
-       if (likely(reset_fail_mask))
+       if (likely(reset_fail_mask)) {
+               struct intel_engine_cs *engine;
+               enum intel_engine_id id;
+
+               /*
+                * GuC is toast at this point - it dead loops after sending the failed
+                * reset notification. So need to manually determine the guilty context.
+                * Note that it should be reliable to do this here because the GuC is
+                * toast and will not be scheduling behind the KMD's back.
+                */
+               for_each_engine_masked(engine, gt, reset_fail_mask, id)
+                       intel_guc_find_hung_context(engine);
+
                intel_gt_handle_error(gt, reset_fail_mask,
                                      I915_ERROR_CAPTURE,
-                                     "GuC failed to reset engine mask=0x%x\n",
+                                     "GuC failed to reset engine mask=0x%x",
                                      reset_fail_mask);
+       }
 }
 
 int intel_guc_engine_failure_process_msg(struct intel_guc *guc,