On Thu, Jan 20, 2022 at 05:34:54PM -0800, John Harrison wrote:

On 1/19/2022 13:24, Matthew Brost wrote:

...

The G2H handler needs to be flushed during a GT reset but a G2H indicating engine reset failure can trigger a GT reset. Add a worker to trigger the GT when an engine reset failure is received to break this

trigger the GT reset?

Yes.

...

circular dependency.

v2: (John Harrison)

• Store engine reset mask
• Fix typo in commit message

Signed-off-by: Matthew Brost matthew.brost@intel.com

drivers/gpu/drm/i915/gt/uc/intel_guc.h | 9 +++++ .../gpu/drm/i915/gt/uc/intel_guc_submission.c | 37 +++++++++++++++++-- 2 files changed, 42 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc.h b/drivers/gpu/drm/i915/gt/uc/intel_guc.h index 9d26a86fe557..c4a9fc7dd246 100644 --- a/drivers/gpu/drm/i915/gt/uc/intel_guc.h +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc.h @@ -119,6 +119,15 @@ struct intel_guc { * function as it might be in an atomic context (no sleeping) */ struct work_struct destroyed_worker;

• /**
  

•  * @reset_worker: worker to trigger a GT reset after an engine
  

•  * reset fails
  

•  */
  

• struct work_struct reset_worker;
  

• /**
  

•  * @reset_mask: mask of engines that failed to reset
  

•  */
  

• intel_engine_mask_t reset_mask;
  

reset_fail_mask might be a less ambiguous name? Same for the worker struct and function.

How about:

struct { worker; mask; } engine_reset_fail;

Matt

John.

...

} submission_state; /** 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 3918f1be114f..514b3060b141 100644 --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c @@ -1731,6 +1731,7 @@ void intel_guc_submission_reset_finish(struct intel_guc *guc) } static void destroyed_worker_func(struct work_struct *w); +static void reset_worker_func(struct work_struct *w); /*

• Set up the memory resources to be shared with the GuC (via the GGTT)

@@ -1761,6 +1762,8 @@ int intel_guc_submission_init(struct intel_guc *guc) INIT_LIST_HEAD(&guc->submission_state.destroyed_contexts); INIT_WORK(&guc->submission_state.destroyed_worker, destroyed_worker_func);

• INIT_WORK(&guc->submission_state.reset_worker,

•   reset_worker_func);
  

  guc->submission_state.guc_ids_bitmap = bitmap_zalloc(NUMBER_MULTI_LRC_GUC_ID(guc), GFP_KERNEL);

@@ -4026,6 +4029,26 @@ guc_lookup_engine(struct intel_guc *guc, u8 guc_class, u8 instance) return gt->engine_class[engine_class][instance]; } +static void reset_worker_func(struct work_struct *w) +{

• struct intel_guc *guc = container_of(w, struct intel_guc,

• 			     submission_state.reset_worker);
  

• struct intel_gt *gt = guc_to_gt(guc);
• intel_engine_mask_t reset_mask;
• unsigned long flags;
• spin_lock_irqsave(&guc->submission_state.lock, flags);
• reset_mask = guc->submission_state.reset_mask;
• guc->submission_state.reset_mask = 0;
• spin_unlock_irqrestore(&guc->submission_state.lock, flags);
• if (likely(reset_mask))

• intel_gt_handle_error(gt, reset_mask,
  

• 		      I915_ERROR_CAPTURE,
  

• 		      "GuC failed to reset engine mask=0x%x\n",
  

• 		      reset_mask);
  

+}

• int intel_guc_engine_failure_process_msg(struct intel_guc *guc, const u32 *msg, u32 len) {

@@ -4033,6 +4056,7 @@ int intel_guc_engine_failure_process_msg(struct intel_guc *guc, struct intel_gt *gt = guc_to_gt(guc); u8 guc_class, instance; u32 reason;

• unsigned long flags; if (unlikely(len != 3)) { drm_err(&gt->i915->drm, "Invalid length %u", len);

@@ -4057,10 +4081,15 @@ int intel_guc_engine_failure_process_msg(struct intel_guc *guc, drm_err(&gt->i915->drm, "GuC engine reset request failed on %d:%d (%s) because 0x%08X", guc_class, instance, engine->name, reason);

• intel_gt_handle_error(gt, engine->mask,

• 	      I915_ERROR_CAPTURE,
  

• 	      "GuC failed to reset %s (reason=0x%08x)\n",
  

• 	      engine->name, reason);
  

• spin_lock_irqsave(&guc->submission_state.lock, flags);
• guc->submission_state.reset_mask |= engine->mask;
• spin_unlock_irqrestore(&guc->submission_state.lock, flags);
• /*

• * A GT reset flushes this worker queue (G2H handler) so we must use
  

• * another worker to trigger a GT reset.
  

• */
  

• queue_work(system_unbound_wq, &guc->submission_state.reset_worker); return 0; }

On 1/19/2022 13:24, Matthew Brost wrote:

Now that the error capture is fully decoupled from fence signalling (request retirement to free memory, which in turn depends on resets) we can safely flush the G2H handler during a GT reset. This is eliminates

This eliminates

John.

corner cases where GuC generated G2H (e.g. engine resets) race with a GT reset.

v2: (John Harrison)

• Fix typo in commit message (s/is/in)

Signed-off-by: Matthew Brost matthew.brost@intel.com Reviewed-by: John Harrison John.C.Harrison@Intel.com

---

.../gpu/drm/i915/gt/uc/intel_guc_submission.c | 18 +----------------- 1 file changed, 1 insertion(+), 17 deletions(-)

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 514b3060b141..406dd2e3f5a9 100644 --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c @@ -1396,8 +1396,6 @@ static void guc_flush_destroyed_contexts(struct intel_guc *guc);

void intel_guc_submission_reset_prepare(struct intel_guc *guc) {

• int i;
• if (unlikely(!guc_submission_initialized(guc))) { /* Reset called during driver load? GuC not yet initialised! */ return;

@@ -1414,21 +1412,7 @@ void intel_guc_submission_reset_prepare(struct intel_guc *guc)

guc_flush_submissions(guc); guc_flush_destroyed_contexts(guc);

• /*

• * Handle any outstanding G2Hs before reset. Call IRQ handler directly
  

• * each pass as interrupt have been disabled. We always scrub for
  

• * outstanding G2H as it is possible for outstanding_submission_g2h to
  

• * be incremented after the context state update.
  

• */
  

• for (i = 0; i < 4 && atomic_read(&guc->outstanding_submission_g2h); ++i) {

• intel_guc_to_host_event_handler(guc);
  

-#define wait_for_reset(guc, wait_var) \

• intel_guc_wait_for_pending_msg(guc, wait_var, false, (HZ / 20))
  

• do {
  

• 	wait_for_reset(guc, &guc->outstanding_submission_g2h);
  

• } while (!list_empty(&guc->ct.requests.incoming));
  

• }

• flush_work(&guc->ct.requests.worker);

  scrub_guc_desc_for_outstanding_g2h(guc); }