[Intel-gfx] [PATCH] drm/i915/selftests: Exercise reset to break stuck GTT eviction

[Tvrtko Ursulin]

On 16/07/2018 14:40, Chris Wilson wrote:
> We must be able to reset the GPU while we are waiting on it to perform
> an eviction (unbinding an active vma). So attach a spinning request to a
> target vma and try and it evict it from a thread to see if that blocks
> indefinitely.
> 
> v2: Add a wait for the thread to start just in case that takes more than
> 10ms...
> v3: complete() not completion_done() to signal the completion.
> 
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> ---
>   .../gpu/drm/i915/selftests/intel_hangcheck.c  | 171 +++++++++++++++++-
>   1 file changed, 169 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/selftests/intel_hangcheck.c b/drivers/gpu/drm/i915/selftests/intel_hangcheck.c
> index 73462a65a330..65d66cdedd26 100644
> --- a/drivers/gpu/drm/i915/selftests/intel_hangcheck.c
> +++ b/drivers/gpu/drm/i915/selftests/intel_hangcheck.c
> @@ -27,6 +27,7 @@
>   #include "../i915_selftest.h"
>   #include "i915_random.h"
>   #include "igt_flush_test.h"
> +#include "igt_wedge_me.h"
>   
>   #include "mock_context.h"
>   #include "mock_drm.h"
> @@ -921,7 +922,7 @@ static u32 fake_hangcheck(struct i915_request *rq, u32 mask)
>   	return reset_count;
>   }
>   
> -static int igt_wait_reset(void *arg)
> +static int igt_reset_wait(void *arg)
>   {
>   	struct drm_i915_private *i915 = arg;
>   	struct i915_request *rq;
> @@ -995,6 +996,170 @@ static int igt_wait_reset(void *arg)
>   	return err;
>   }
>   
> +struct evict_vma {
> +	struct completion completion;
> +	struct i915_vma *vma;
> +};
> +
> +static int evict_vma(void *data)
> +{
> +	struct evict_vma *arg = data;
> +	struct i915_address_space *vm = arg->vma->vm;
> +	struct drm_i915_private *i915 = vm->i915;
> +	struct drm_mm_node evict = arg->vma->node;
> +	int err;
> +
> +	complete(&arg->completion);
> +
> +	mutex_lock(&i915->drm.struct_mutex);
> +	err = i915_gem_evict_for_node(vm, &evict, 0);
> +	mutex_unlock(&i915->drm.struct_mutex);
> +
> +	return err;
> +}
> +
> +static int __igt_reset_evict_vma(struct drm_i915_private *i915,
> +				 struct i915_address_space *vm)
> +{
> +	struct drm_i915_gem_object *obj;
> +	struct task_struct *tsk = NULL;
> +	struct i915_request *rq;
> +	struct evict_vma arg;
> +	struct hang h;
> +	int err;
> +
> +	if (!intel_engine_can_store_dword(i915->engine[RCS]))
> +		return 0;
> +
> +	/* Check that we can recover an unbind stuck on a hanging request */
> +
> +	global_reset_lock(i915);
> +
> +	mutex_lock(&i915->drm.struct_mutex);
> +	err = hang_init(&h, i915);
> +	if (err)
> +		goto unlock;
> +
> +	obj = i915_gem_object_create_internal(i915, PAGE_SIZE);
> +	if (IS_ERR(obj)) {
> +		err = PTR_ERR(obj);
> +		goto fini;
> +	}
> +
> +	arg.vma = i915_vma_instance(obj, vm, NULL);
> +	if (IS_ERR(arg.vma)) {
> +		err = PTR_ERR(arg.vma);
> +		goto out_obj;
> +	}
> +
> +	rq = hang_create_request(&h, i915->engine[RCS]);
> +	if (IS_ERR(rq)) {
> +		err = PTR_ERR(rq);
> +		goto out_obj;
> +	}
> +
> +	err = i915_vma_pin(arg.vma, 0, 0,
> +			   i915_vma_is_ggtt(arg.vma) ? PIN_GLOBAL : PIN_USER);
> +	if (err)
> +		goto out_obj;
> +
> +	err = i915_vma_move_to_active(arg.vma, rq, EXEC_OBJECT_WRITE);
> +	i915_vma_unpin(arg.vma);
> +
> +	i915_request_get(rq);
> +	i915_request_add(rq);
> +	if (err)
> +		goto out_rq;
> +
> +	mutex_unlock(&i915->drm.struct_mutex);
> +
> +	if (!wait_until_running(&h, rq)) {
> +		struct drm_printer p = drm_info_printer(i915->drm.dev);
> +
> +		pr_err("%s: Failed to start request %x, at %x\n",
> +		       __func__, rq->fence.seqno, hws_seqno(&h, rq));
> +		intel_engine_dump(rq->engine, &p, "%s\n", rq->engine->name);
> +
> +		i915_gem_set_wedged(i915);
> +		goto out_reset;
> +	}
> +
> +	init_completion(&arg.completion);
> +
> +	tsk = kthread_run(evict_vma, &arg, "igt/evict_vma");
> +	if (IS_ERR(tsk)) {
> +		err = PTR_ERR(tsk);
> +		tsk = NULL;
> +		goto out_reset;
> +	}
> +
> +	wait_for_completion(&arg.completion);
> +
> +	if (wait_for(waitqueue_active(&rq->execute), 10)) {
> +		struct drm_printer p = drm_info_printer(i915->drm.dev);
> +
> +		pr_err("igt/evict_vma kthread did not wait\n");
> +		intel_engine_dump(rq->engine, &p, "%s\n", rq->engine->name);
> +
> +		i915_gem_set_wedged(i915);
> +		goto out_reset;
> +	}
> +
> +out_reset:
> +	fake_hangcheck(rq, intel_engine_flag(rq->engine));
> +
> +	if (tsk) {
> +		struct igt_wedge_me w;
> +
> +		/* The reset, even indirectly, should take less than 10ms. */
> +		igt_wedge_on_timeout(&w, i915, HZ / 10 /* 100ms timeout*/)
> +			err = kthread_stop(tsk);
> +	}
> +
> +	mutex_lock(&i915->drm.struct_mutex);
> +out_rq:
> +	i915_request_put(rq);
> +out_obj:
> +	i915_gem_object_put(obj);
> +fini:
> +	hang_fini(&h);
> +unlock:
> +	mutex_unlock(&i915->drm.struct_mutex);
> +	global_reset_unlock(i915);
> +
> +	if (i915_terminally_wedged(&i915->gpu_error))
> +		return -EIO;
> +
> +	return err;
> +}
> +
> +static int igt_reset_evict_ggtt(void *arg)
> +{
> +	struct drm_i915_private *i915 = arg;
> +
> +	return __igt_reset_evict_vma(i915, &i915->ggtt.vm);
> +}
> +
> +static int igt_reset_evict_ppgtt(void *arg)
> +{
> +	struct drm_i915_private *i915 = arg;
> +	struct i915_gem_context *ctx;
> +	int err;
> +
> +	mutex_lock(&i915->drm.struct_mutex);
> +	ctx = kernel_context(i915);
> +	mutex_unlock(&i915->drm.struct_mutex);
> +	if (IS_ERR(ctx))
> +		return PTR_ERR(ctx);
> +
> +	err = 0;
> +	if (ctx->ppgtt) /* aliasing == global gtt locking, covered above */
> +		err = __igt_reset_evict_vma(i915, &ctx->ppgtt->vm);
> +
> +	kernel_context_close(ctx);
> +	return err;
> +}
> +
>   static int wait_for_others(struct drm_i915_private *i915,
>   			   struct intel_engine_cs *exclude)
>   {
> @@ -1240,8 +1405,10 @@ int intel_hangcheck_live_selftests(struct drm_i915_private *i915)
>   		SUBTEST(igt_reset_idle_engine),
>   		SUBTEST(igt_reset_active_engine),
>   		SUBTEST(igt_reset_engines),
> -		SUBTEST(igt_wait_reset),
>   		SUBTEST(igt_reset_queue),
> +		SUBTEST(igt_reset_wait),
> +		SUBTEST(igt_reset_evict_ggtt),
> +		SUBTEST(igt_reset_evict_ppgtt),
>   		SUBTEST(igt_handle_error),
>   	};
>   	bool saved_hangcheck;
> 

Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>

Regards,

Tvrtko