Re: [Intel-gfx] [PATCH 2/3] drm/i915/guc: Add work queue to trigger a GT reset

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

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;
> >   }
>