Re: [PATCH 35/47] drm/i915/guc: Handle context reset notification

[John Harrison <john.c.harrison@xxxxxxxxx>]

On 6/24/2021 00:05, Matthew Brost wrote:
> GuC will issue a reset on detecting an engine hang and will notify
> the driver via a G2H message. The driver will service the notification
> by resetting the guilty context to a simple state or banning it
> completely.
>
> Cc: Matthew Brost <matthew.brost@xxxxxxxxx>
> Cc: John Harrison <John.C.Harrison@xxxxxxxxx>
> Signed-off-by: Matthew Brost <matthew.brost@xxxxxxxxx>
> ---
>   drivers/gpu/drm/i915/gt/uc/intel_guc.h        |  2 ++
>   drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c     |  3 ++
>   .../gpu/drm/i915/gt/uc/intel_guc_submission.c | 35 +++++++++++++++++++
>   drivers/gpu/drm/i915/i915_trace.h             | 10 ++++++
>   4 files changed, 50 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc.h b/drivers/gpu/drm/i915/gt/uc/intel_guc.h
> index 85ef6767f13b..e94b0ef733da 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc.h
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc.h
> @@ -262,6 +262,8 @@ int intel_guc_deregister_done_process_msg(struct intel_guc *guc,
>   					  const u32 *msg, u32 len);
>   int intel_guc_sched_done_process_msg(struct intel_guc *guc,
>   				     const u32 *msg, u32 len);
> +int intel_guc_context_reset_process_msg(struct intel_guc *guc,
> +					const u32 *msg, u32 len);
>   
>   void intel_guc_submission_reset_prepare(struct intel_guc *guc);
>   void intel_guc_submission_reset(struct intel_guc *guc, bool stalled);
> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c
> index 4ed074df88e5..a2020373b8e8 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c
> @@ -945,6 +945,9 @@ static int ct_process_request(struct intel_guc_ct *ct, struct ct_incoming_msg *r
>   	case INTEL_GUC_ACTION_SCHED_CONTEXT_MODE_DONE:
>   		ret = intel_guc_sched_done_process_msg(guc, payload, len);
>   		break;
> +	case INTEL_GUC_ACTION_CONTEXT_RESET_NOTIFICATION:
> +		ret = intel_guc_context_reset_process_msg(guc, payload, len);
> +		break;
>   	default:
>   		ret = -EOPNOTSUPP;
>   		break;
> 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 16b61fe71b07..9845c5bd9832 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> @@ -2192,6 +2192,41 @@ int intel_guc_sched_done_process_msg(struct intel_guc *guc,
>   	return 0;
>   }
>   
> +static void guc_context_replay(struct intel_context *ce)
> +{
> +	struct i915_sched_engine *sched_engine = ce->engine->sched_engine;
> +
> +	__guc_reset_context(ce, true);
> +	tasklet_hi_schedule(&sched_engine->tasklet);
> +}
> +
> +static void guc_handle_context_reset(struct intel_guc *guc,
> +				     struct intel_context *ce)
> +{
> +	trace_intel_context_reset(ce);
> +	guc_context_replay(ce);
> +}
> +
> +int intel_guc_context_reset_process_msg(struct intel_guc *guc,
> +					const u32 *msg, u32 len)
> +{
> +	struct intel_context *ce;
> +	int desc_idx = msg[0];
Should do this dereference after checking the length? Or is it 
guaranteed that the length cannot be zero?

John.

> +
> +	if (unlikely(len != 1)) {
> +		drm_dbg(&guc_to_gt(guc)->i915->drm, "Invalid length %u", len);
> +		return -EPROTO;
> +	}
> +
> +	ce = g2h_context_lookup(guc, desc_idx);
> +	if (unlikely(!ce))
> +		return -EPROTO;
> +
> +	guc_handle_context_reset(guc, ce);
> +
> +	return 0;
> +}
> +
>   void intel_guc_log_submission_info(struct intel_guc *guc,
>   				   struct drm_printer *p)
>   {
> diff --git a/drivers/gpu/drm/i915/i915_trace.h b/drivers/gpu/drm/i915/i915_trace.h
> index 97c2e83984ed..c095c4d39456 100644
> --- a/drivers/gpu/drm/i915/i915_trace.h
> +++ b/drivers/gpu/drm/i915/i915_trace.h
> @@ -929,6 +929,11 @@ DECLARE_EVENT_CLASS(intel_context,
>   		      __entry->guc_sched_state_no_lock)
>   );
>   
> +DEFINE_EVENT(intel_context, intel_context_reset,
> +	     TP_PROTO(struct intel_context *ce),
> +	     TP_ARGS(ce)
> +);
> +
>   DEFINE_EVENT(intel_context, intel_context_register,
>   	     TP_PROTO(struct intel_context *ce),
>   	     TP_ARGS(ce)
> @@ -1026,6 +1031,11 @@ trace_i915_request_out(struct i915_request *rq)
>   {
>   }
>   
> +static inline void
> +trace_intel_context_reset(struct intel_context *ce)
> +{
> +}
> +
>   static inline void
>   trace_intel_context_register(struct intel_context *ce)
>   {