[Intel-gfx] [PATCH] drm/i915/gt: Confirm the context survives execution

[Tvrtko Ursulin]

On 13/10/2020 16:35, Chris Wilson wrote:
> Repeat our sanitychecks from before execution to after execution. One
> expects that if we were to see these, the gpu would already be on fire,
> but the timing may be informative.
> 
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> ---
>   drivers/gpu/drm/i915/gt/intel_lrc.c | 10 +++++++---
>   1 file changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c
> index 287537089c77..3dbdd5d0cb60 100644
> --- a/drivers/gpu/drm/i915/gt/intel_lrc.c
> +++ b/drivers/gpu/drm/i915/gt/intel_lrc.c
> @@ -1216,7 +1216,8 @@ static void intel_engine_context_out(struct intel_engine_cs *engine)
>   
>   static void
>   execlists_check_context(const struct intel_context *ce,
> -			const struct intel_engine_cs *engine)
> +			const struct intel_engine_cs *engine,
> +			const char *when)
>   {
>   	const struct intel_ring *ring = ce->ring;
>   	u32 *regs = ce->lrc_reg_state;
> @@ -1251,7 +1252,7 @@ execlists_check_context(const struct intel_context *ce,
>   		valid = false;
>   	}
>   
> -	WARN_ONCE(!valid, "Invalid lrc state found before submission\n");
> +	WARN_ONCE(!valid, "Invalid lrc state found %s submission\n", when);
>   }
>   
>   static void restore_default_state(struct intel_context *ce,
> @@ -1347,7 +1348,7 @@ __execlists_schedule_in(struct i915_request *rq)
>   		reset_active(rq, engine);
>   
>   	if (IS_ENABLED(CONFIG_DRM_I915_DEBUG_GEM))
> -		execlists_check_context(ce, engine);
> +		execlists_check_context(ce, engine, "before");
>   
>   	if (ce->tag) {
>   		/* Use a fixed tag for OA and friends */
> @@ -1418,6 +1419,9 @@ __execlists_schedule_out(struct i915_request *rq,
>   	 * refrain from doing non-trivial work here.
>   	 */
>   
> +	if (IS_ENABLED(CONFIG_DRM_I915_DEBUG_GEM))
> +		execlists_check_context(ce, engine, "after");
> +

CI failures here are either something super scary or a simple mistake 
which I cannot see. Or is engine retire, possible queued up before, 
racing with current schedule_out?

Regards,

Tvrtko

>   	/*
>   	 * If we have just completed this context, the engine may now be
>   	 * idle and we want to re-enter powersaving.
>