drm/i915: Individual request cancellation

Currently, we cancel outstanding requests within a context when the
context is closed. We may also want to cancel individual requests using
the same graceful preemption mechanism.

v2 (Tvrtko):
 * Cancel waiters carefully considering no timeline lock and RCU.
 * Fixed selftests.

v3 (Tvrtko):
 * Remove error propagation to waiters for now.

v4 (Tvrtko):
 * Rebase for extracted i915_request_active_engine. (Matt)
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
[danvet: Resolve conflict because intel_engine_flush_scheduler is
still called intel_engine_flush_submission]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210324121335.2307063-3-tvrtko.ursulin@linux.intel.com

drivers/gpu/drm/i915/gt/intel_engine_heartbeat.c

@@ -279,6 +279,7 @@ int intel_engine_pulse(struct intel_engine_cs *engine)
 		mutex_unlock(&ce->timeline->mutex);
 	}
 
+	intel_engine_flush_submission(engine);
 	intel_engine_pm_put(engine);
 	return err;
 }

drivers/gpu/drm/i915/gt/intel_execlists_submission.c

@@ -470,6 +470,11 @@ static void reset_active(struct i915_request *rq,
 	ce->lrc.lrca = lrc_update_regs(ce, engine, head);
 }
 
+static bool bad_request(const struct i915_request *rq)
+{
+	return rq->fence.error && i915_request_started(rq);
+}
+
 static struct intel_engine_cs *
 __execlists_schedule_in(struct i915_request *rq)
 {
@@ -482,7 +487,7 @@ __execlists_schedule_in(struct i915_request *rq)
 		     !intel_engine_has_heartbeat(engine)))
 		intel_context_set_banned(ce);
 
-	if (unlikely(intel_context_is_banned(ce)))
+	if (unlikely(intel_context_is_banned(ce) || bad_request(rq)))
 		reset_active(rq, engine);
 
 	if (IS_ENABLED(CONFIG_DRM_I915_DEBUG_GEM))
@@ -1208,7 +1213,7 @@ static unsigned long active_preempt_timeout(struct intel_engine_cs *engine,
 		return 0;
 
 	/* Force a fast reset for terminated contexts (ignoring sysfs!) */
-	if (unlikely(intel_context_is_banned(rq->context)))
+	if (unlikely(intel_context_is_banned(rq->context) || bad_request(rq)))
 		return 1;
 
 	return READ_ONCE(engine->props.preempt_timeout_ms);

drivers/gpu/drm/i915/i915_request.c

@@ -33,7 +33,10 @@
 #include "gem/i915_gem_context.h"
 #include "gt/intel_breadcrumbs.h"
 #include "gt/intel_context.h"
+#include "gt/intel_engine.h"
+#include "gt/intel_engine_heartbeat.h"
 #include "gt/intel_gpu_commands.h"
+#include "gt/intel_reset.h"
 #include "gt/intel_ring.h"
 #include "gt/intel_rps.h"
 
@@ -542,20 +545,22 @@ void __i915_request_skip(struct i915_request *rq)
 	rq->infix = rq->postfix;
 }
 
-void i915_request_set_error_once(struct i915_request *rq, int error)
+bool i915_request_set_error_once(struct i915_request *rq, int error)
 {
 	int old;
 
 	GEM_BUG_ON(!IS_ERR_VALUE((long)error));
 
 	if (i915_request_signaled(rq))
-		return;
+		return false;
 
 	old = READ_ONCE(rq->fence.error);
 	do {
 		if (fatal_error(old))
-			return;
+			return false;
 	} while (!try_cmpxchg(&rq->fence.error, &old, error));
+
+	return true;
 }
 
 void i915_request_mark_eio(struct i915_request *rq)
@@ -722,6 +727,28 @@ void i915_request_unsubmit(struct i915_request *request)
 	spin_unlock_irqrestore(&engine->active.lock, flags);
 }
 
+static void __cancel_request(struct i915_request *rq)
+{
+	struct intel_engine_cs *engine = NULL;
+
+	i915_request_active_engine(rq, &engine);
+
+	if (engine && intel_engine_pulse(engine))
+		intel_gt_handle_error(engine->gt, engine->mask, 0,
+				      "request cancellation by %s",
+				      current->comm);
+}
+
+void i915_request_cancel(struct i915_request *rq, int error)
+{
+	if (!i915_request_set_error_once(rq, error))
+		return;
+
+	set_bit(I915_FENCE_FLAG_SENTINEL, &rq->fence.flags);
+
+	__cancel_request(rq);
+}
+
 static int __i915_sw_fence_call
 submit_notify(struct i915_sw_fence *fence, enum i915_sw_fence_notify state)
 {

drivers/gpu/drm/i915/i915_request.h

@@ -300,7 +300,7 @@ struct i915_request * __must_check
 i915_request_create(struct intel_context *ce);
 
 void __i915_request_skip(struct i915_request *rq);
-void i915_request_set_error_once(struct i915_request *rq, int error);
+bool i915_request_set_error_once(struct i915_request *rq, int error);
 void i915_request_mark_eio(struct i915_request *rq);
 
 struct i915_request *__i915_request_commit(struct i915_request *request);
@@ -356,6 +356,8 @@ void i915_request_submit(struct i915_request *request);
 void __i915_request_unsubmit(struct i915_request *request);
 void i915_request_unsubmit(struct i915_request *request);
 
+void i915_request_cancel(struct i915_request *rq, int error);
+
 long i915_request_wait(struct i915_request *rq,
 		       unsigned int flags,
 		       long timeout)

drivers/gpu/drm/i915/selftests/i915_request.c

@@ -609,6 +609,206 @@ static int live_nop_request(void *arg)
 	return err;
 }
 
+static int __cancel_inactive(struct intel_engine_cs *engine)
+{
+	struct intel_context *ce;
+	struct igt_spinner spin;
+	struct i915_request *rq;
+	int err = 0;
+
+	if (igt_spinner_init(&spin, engine->gt))
+		return -ENOMEM;
+
+	ce = intel_context_create(engine);
+	if (IS_ERR(ce)) {
+		err = PTR_ERR(ce);
+		goto out_spin;
+	}
+
+	rq = igt_spinner_create_request(&spin, ce, MI_ARB_CHECK);
+	if (IS_ERR(rq)) {
+		err = PTR_ERR(rq);
+		goto out_ce;
+	}
+
+	pr_debug("%s: Cancelling inactive request\n", engine->name);
+	i915_request_cancel(rq, -EINTR);
+	i915_request_get(rq);
+	i915_request_add(rq);
+
+	if (i915_request_wait(rq, 0, HZ / 5) < 0) {
+		struct drm_printer p = drm_info_printer(engine->i915->drm.dev);
+
+		pr_err("%s: Failed to cancel inactive request\n", engine->name);
+		intel_engine_dump(engine, &p, "%s\n", engine->name);
+		err = -ETIME;
+		goto out_rq;
+	}
+
+	if (rq->fence.error != -EINTR) {
+		pr_err("%s: fence not cancelled (%u)\n",
+		       engine->name, rq->fence.error);
+		err = -EINVAL;
+	}
+
+out_rq:
+	i915_request_put(rq);
+out_ce:
+	intel_context_put(ce);
+out_spin:
+	igt_spinner_fini(&spin);
+	if (err)
+		pr_err("%s: %s error %d\n", __func__, engine->name, err);
+	return err;
+}
+
+static int __cancel_active(struct intel_engine_cs *engine)
+{
+	struct intel_context *ce;
+	struct igt_spinner spin;
+	struct i915_request *rq;
+	int err = 0;
+
+	if (igt_spinner_init(&spin, engine->gt))
+		return -ENOMEM;
+
+	ce = intel_context_create(engine);
+	if (IS_ERR(ce)) {
+		err = PTR_ERR(ce);
+		goto out_spin;
+	}
+
+	rq = igt_spinner_create_request(&spin, ce, MI_ARB_CHECK);
+	if (IS_ERR(rq)) {
+		err = PTR_ERR(rq);
+		goto out_ce;
+	}
+
+	pr_debug("%s: Cancelling active request\n", engine->name);
+	i915_request_get(rq);
+	i915_request_add(rq);
+	if (!igt_wait_for_spinner(&spin, rq)) {
+		struct drm_printer p = drm_info_printer(engine->i915->drm.dev);
+
+		pr_err("Failed to start spinner on %s\n", engine->name);
+		intel_engine_dump(engine, &p, "%s\n", engine->name);
+		err = -ETIME;
+		goto out_rq;
+	}
+	i915_request_cancel(rq, -EINTR);
+
+	if (i915_request_wait(rq, 0, HZ / 5) < 0) {
+		struct drm_printer p = drm_info_printer(engine->i915->drm.dev);
+
+		pr_err("%s: Failed to cancel active request\n", engine->name);
+		intel_engine_dump(engine, &p, "%s\n", engine->name);
+		err = -ETIME;
+		goto out_rq;
+	}
+
+	if (rq->fence.error != -EINTR) {
+		pr_err("%s: fence not cancelled (%u)\n",
+		       engine->name, rq->fence.error);
+		err = -EINVAL;
+	}
+
+out_rq:
+	i915_request_put(rq);
+out_ce:
+	intel_context_put(ce);
+out_spin:
+	igt_spinner_fini(&spin);
+	if (err)
+		pr_err("%s: %s error %d\n", __func__, engine->name, err);
+	return err;
+}
+
+static int __cancel_completed(struct intel_engine_cs *engine)
+{
+	struct intel_context *ce;
+	struct igt_spinner spin;
+	struct i915_request *rq;
+	int err = 0;
+
+	if (igt_spinner_init(&spin, engine->gt))
+		return -ENOMEM;
+
+	ce = intel_context_create(engine);
+	if (IS_ERR(ce)) {
+		err = PTR_ERR(ce);
+		goto out_spin;
+	}
+
+	rq = igt_spinner_create_request(&spin, ce, MI_ARB_CHECK);
+	if (IS_ERR(rq)) {
+		err = PTR_ERR(rq);
+		goto out_ce;
+	}
+	igt_spinner_end(&spin);
+	i915_request_get(rq);
+	i915_request_add(rq);
+
+	if (i915_request_wait(rq, 0, HZ / 5) < 0) {
+		err = -ETIME;
+		goto out_rq;
+	}
+
+	pr_debug("%s: Cancelling completed request\n", engine->name);
+	i915_request_cancel(rq, -EINTR);
+	if (rq->fence.error) {
+		pr_err("%s: fence not cancelled (%u)\n",
+		       engine->name, rq->fence.error);
+		err = -EINVAL;
+	}
+
+out_rq:
+	i915_request_put(rq);
+out_ce:
+	intel_context_put(ce);
+out_spin:
+	igt_spinner_fini(&spin);
+	if (err)
+		pr_err("%s: %s error %d\n", __func__, engine->name, err);
+	return err;
+}
+
+static int live_cancel_request(void *arg)
+{
+	struct drm_i915_private *i915 = arg;
+	struct intel_engine_cs *engine;
+
+	/*
+	 * Check cancellation of requests. We expect to be able to immediately
+	 * cancel active requests, even if they are currently on the GPU.
+	 */
+
+	for_each_uabi_engine(engine, i915) {
+		struct igt_live_test t;
+		int err, err2;
+
+		if (!intel_engine_has_preemption(engine))
+			continue;
+
+		err = igt_live_test_begin(&t, i915, __func__, engine->name);
+		if (err)
+			return err;
+
+		err = __cancel_inactive(engine);
+		if (err == 0)
+			err = __cancel_active(engine);
+		if (err == 0)
+			err = __cancel_completed(engine);
+
+		err2 = igt_live_test_end(&t);
+		if (err)
+			return err;
+		if (err2)
+			return err2;
+	}
+
+	return 0;
+}
+
 static struct i915_vma *empty_batch(struct drm_i915_private *i915)
 {
 	struct drm_i915_gem_object *obj;
@@ -1486,6 +1686,7 @@ int i915_request_live_selftests(struct drm_i915_private *i915)
 		SUBTEST(live_sequential_engines),
 		SUBTEST(live_parallel_engines),
 		SUBTEST(live_empty_request),
+		SUBTEST(live_cancel_request),
 		SUBTEST(live_breadcrumbs_smoketest),
 	};