Re: [Intel-gfx] [PATCH 3/3] drm/i915/selftests: Add initial GuC selftest for scrubbing lost G2H

[Daniel Vetter <daniel@ffwll.ch>]

On Sun, Aug 08, 2021 at 11:07:57AM -0700, Matthew Brost wrote:
> While debugging an issue with full GT resets I went down a rabbit hole
> thinking the scrubbing of lost G2H wasn't working correctly. This proved
> to be incorrect as this was working just fine but this chase inspired me
> to write a selftest to prove that this works. This simple selftest
> injects errors dropping various G2H and then issues a full GT reset
> proving that the scrubbing of these G2H doesn't blow up.
> 
> Signed-off-by: Matthew Brost <matthew.brost@intel.com>
> ---
>  drivers/gpu/drm/i915/gt/intel_context_types.h |   4 +
>  .../gpu/drm/i915/gt/uc/intel_guc_submission.c |  18 +++
>  drivers/gpu/drm/i915/gt/uc/selftest_guc.c     | 126 ++++++++++++++++++
>  .../drm/i915/selftests/i915_live_selftests.h  |   1 +
>  .../i915/selftests/intel_scheduler_helpers.c  |  12 ++
>  .../i915/selftests/intel_scheduler_helpers.h  |   2 +
>  6 files changed, 163 insertions(+)
>  create mode 100644 drivers/gpu/drm/i915/gt/uc/selftest_guc.c
> 
> diff --git a/drivers/gpu/drm/i915/gt/intel_context_types.h b/drivers/gpu/drm/i915/gt/intel_context_types.h
> index e54351a170e2..fec5ff7ef168 100644
> --- a/drivers/gpu/drm/i915/gt/intel_context_types.h
> +++ b/drivers/gpu/drm/i915/gt/intel_context_types.h
> @@ -198,6 +198,10 @@ struct intel_context {
>  	 */
>  	u8 guc_prio;
>  	u32 guc_prio_count[GUC_CLIENT_PRIORITY_NUM];
> +

I know the existing stuff isn't following this at all, but for anything
new we really should put some kerneldoc into structures. This probably
means you need to open-code the #ifdef here, since this macro will likely
upset kerneldoc parsing.

> +	I915_SELFTEST_DECLARE(bool drop_schedule_enable);
> +	I915_SELFTEST_DECLARE(bool drop_schedule_disable);
> +	I915_SELFTEST_DECLARE(bool drop_deregister);
>  };
>  
>  #endif /* __INTEL_CONTEXT_TYPES__ */
> 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 cd8df078ca87..d13dc56bae43 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> @@ -2618,6 +2618,11 @@ int intel_guc_deregister_done_process_msg(struct intel_guc *guc,
>  
>  	trace_intel_context_deregister_done(ce);
>  
> +	if (I915_SELFTEST_ONLY(ce->drop_deregister)) {
> +		I915_SELFTEST_DECLARE(ce->drop_deregister = false;)

This macro wrapping is quite nasty, can't we just #ifdef this? Especially
the _DECLARE name really doesn't expect a statement.

Aside from these bikesheds I don't have a much to say on the test logic
itself, since I'm far from knowledgable on guc stuff ...
-Daniel


> +		return 0;
> +	}
> +
>  	if (context_wait_for_deregister_to_register(ce)) {
>  		struct intel_runtime_pm *runtime_pm =
>  			&ce->engine->gt->i915->runtime_pm;
> @@ -2672,10 +2677,19 @@ int intel_guc_sched_done_process_msg(struct intel_guc *guc,
>  	trace_intel_context_sched_done(ce);
>  
>  	if (context_pending_enable(ce)) {
> +		if (I915_SELFTEST_ONLY(ce->drop_schedule_enable)) {
> +			I915_SELFTEST_DECLARE(ce->drop_schedule_enable = false;)
> +			return 0;
> +		}
>  		clr_context_pending_enable(ce);
>  	} else if (context_pending_disable(ce)) {
>  		bool banned;
>  
> +		if (I915_SELFTEST_ONLY(ce->drop_schedule_disable)) {
> +			I915_SELFTEST_DECLARE(ce->drop_schedule_disable = false;)
> +			return 0;
> +		}
> +
>  		/*
>  		 * Unpin must be done before __guc_signal_context_fence,
>  		 * otherwise a race exists between the requests getting
> @@ -3047,3 +3061,7 @@ bool intel_guc_virtual_engine_has_heartbeat(const struct intel_engine_cs *ve)
>  
>  	return false;
>  }
> +
> +#if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
> +#include "selftest_guc.c"
> +#endif
> diff --git a/drivers/gpu/drm/i915/gt/uc/selftest_guc.c b/drivers/gpu/drm/i915/gt/uc/selftest_guc.c
> new file mode 100644
> index 000000000000..46ca6554f65d
> --- /dev/null
> +++ b/drivers/gpu/drm/i915/gt/uc/selftest_guc.c
> @@ -0,0 +1,126 @@
> +// SPDX-License-Identifier: MIT
> +/*
> + * Copyright �� 2021 Intel Corporation
> + */
> +
> +#include "selftests/intel_scheduler_helpers.h"
> +
> +static struct i915_request *nop_user_request(struct intel_context *ce,
> +					     struct i915_request *from)
> +{
> +	struct i915_request *rq;
> +	int ret;
> +
> +	rq = intel_context_create_request(ce);
> +	if (IS_ERR(rq))
> +		return rq;
> +
> +	if (from) {
> +		ret = i915_sw_fence_await_dma_fence(&rq->submit,
> +						    &from->fence, 0,
> +						    I915_FENCE_GFP);
> +		if (ret < 0) {
> +			i915_request_put(rq);
> +			return ERR_PTR(ret);
> +		}
> +	}
> +
> +	i915_request_get(rq);
> +	i915_request_add(rq);
> +
> +	return rq;
> +}
> +
> +static int intel_guc_scrub_ctbs(void *arg)
> +{
> +	struct intel_gt *gt = arg;
> +	int ret = 0;
> +	int i;
> +	struct i915_request *last[3] = {NULL, NULL, NULL}, *rq;
> +	intel_wakeref_t wakeref;
> +	struct intel_engine_cs *engine;
> +	struct intel_context *ce;
> +
> +	wakeref = intel_runtime_pm_get(gt->uncore->rpm);
> +	engine = intel_selftest_find_any_engine(gt);
> +
> +	/* Submit requests and inject errors forcing G2H to be dropped */
> +	for (i = 0; i < 3; ++i) {
> +		ce = intel_context_create(engine);
> +		if (IS_ERR(ce)) {
> +			ret = PTR_ERR(ce);
> +			pr_err("Failed to create context, %d: %d\n", i, ret);
> +			goto err;
> +		}
> +
> +		switch(i) {
> +		case 0:
> +			ce->drop_schedule_enable = true;
> +			break;
> +		case 1:
> +			ce->drop_schedule_disable = true;
> +			break;
> +		case 2:
> +			ce->drop_deregister = true;
> +			break;
> +		}
> +
> +		rq = nop_user_request(ce, NULL);
> +		intel_context_put(ce);
> +
> +		if (IS_ERR(rq)) {
> +			ret = PTR_ERR(rq);
> +			pr_err("Failed to create request, %d: %d\n", i, ret);
> +			goto err;
> +		}
> +
> +		last[i] = rq;
> +	}
> +
> +	for (i = 0; i < 3; ++i) {
> +		ret = i915_request_wait(last[i], 0, HZ);
> +		if (ret < 0) {
> +			pr_err("Last request failed to complete: %d\n", ret);
> +			goto err;
> +		}
> +		i915_request_put(last[i]);
> +		last[i] = NULL;
> +	}
> +
> +	/* Force all H2G / G2H to be submitted / processed */
> +	intel_gt_retire_requests(gt);
> +	msleep(500);
> +
> +	/* Scrub missing G2H */
> +	intel_gt_handle_error(engine->gt, -1, 0, "selftest reset");
> +
> +	ret = intel_gt_wait_for_idle(gt, HZ);
> +	if (ret < 0) {
> +		pr_err("GT failed to idle: %d\n", ret);
> +		goto err;
> +	}
> +
> +err:
> +	for (i = 0; i < 3; ++i)
> +		if (last[i])
> +			i915_request_put(last[i]);
> +	intel_runtime_pm_put(gt->uncore->rpm, wakeref);
> +
> +	return ret;
> +}
> +
> +int intel_guc_live_selftests(struct drm_i915_private *i915)
> +{
> +	static const struct i915_subtest tests[] = {
> +		SUBTEST(intel_guc_scrub_ctbs),
> +	};
> +	struct intel_gt *gt = &i915->gt;
> +
> +	if (intel_gt_is_wedged(gt))
> +		return 0;
> +
> +	if (!intel_uc_uses_guc_submission(&gt->uc))
> +		return 0;
> +
> +	return intel_gt_live_subtests(tests, gt);
> +}
> diff --git a/drivers/gpu/drm/i915/selftests/i915_live_selftests.h b/drivers/gpu/drm/i915/selftests/i915_live_selftests.h
> index cfa5c4165a4f..3cf6758931f9 100644
> --- a/drivers/gpu/drm/i915/selftests/i915_live_selftests.h
> +++ b/drivers/gpu/drm/i915/selftests/i915_live_selftests.h
> @@ -47,5 +47,6 @@ selftest(execlists, intel_execlists_live_selftests)
>  selftest(ring_submission, intel_ring_submission_live_selftests)
>  selftest(perf, i915_perf_live_selftests)
>  selftest(slpc, intel_slpc_live_selftests)
> +selftest(guc, intel_guc_live_selftests)
>  /* Here be dragons: keep last to run last! */
>  selftest(late_gt_pm, intel_gt_pm_late_selftests)
> diff --git a/drivers/gpu/drm/i915/selftests/intel_scheduler_helpers.c b/drivers/gpu/drm/i915/selftests/intel_scheduler_helpers.c
> index 4b328346b48a..310fb83c527e 100644
> --- a/drivers/gpu/drm/i915/selftests/intel_scheduler_helpers.c
> +++ b/drivers/gpu/drm/i915/selftests/intel_scheduler_helpers.c
> @@ -14,6 +14,18 @@
>  #define REDUCED_PREEMPT		10
>  #define WAIT_FOR_RESET_TIME	10000
>  
> +struct intel_engine_cs *intel_selftest_find_any_engine(struct intel_gt *gt)
> +{
> +	struct intel_engine_cs *engine;
> +	enum intel_engine_id id;
> +
> +	for_each_engine(engine, gt, id)
> +		return engine;
> +
> +	pr_err("No valid engine found!\n");
> +	return NULL;
> +}
> +
>  int intel_selftest_modify_policy(struct intel_engine_cs *engine,
>  				 struct intel_selftest_saved_policy *saved,
>  				 u32 modify_type)
> diff --git a/drivers/gpu/drm/i915/selftests/intel_scheduler_helpers.h b/drivers/gpu/drm/i915/selftests/intel_scheduler_helpers.h
> index 35c098601ac0..ae60bb507f45 100644
> --- a/drivers/gpu/drm/i915/selftests/intel_scheduler_helpers.h
> +++ b/drivers/gpu/drm/i915/selftests/intel_scheduler_helpers.h
> @@ -10,6 +10,7 @@
>  
>  struct i915_request;
>  struct intel_engine_cs;
> +struct intel_gt;
>  
>  struct intel_selftest_saved_policy {
>  	u32 flags;
> @@ -23,6 +24,7 @@ enum selftest_scheduler_modify {
>  	SELFTEST_SCHEDULER_MODIFY_FAST_RESET,
>  };
>  
> +struct intel_engine_cs *intel_selftest_find_any_engine(struct intel_gt *gt);
>  int intel_selftest_modify_policy(struct intel_engine_cs *engine,
>  				 struct intel_selftest_saved_policy *saved,
>  				 enum selftest_scheduler_modify modify_type);
> -- 
> 2.28.0
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch