4 files changed, 46 insertions, 3 deletions

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index c55b5ec8c16b..0ed102d87d5a 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -3666,6 +3666,12 @@ const char *i915_scheduler_queue_status_str(
 	case I915_SQS_FLYING:
 	return "Flying";
 
+	case I915_SQS_OVERTAKING:
+	return "Overtaking";
+
+	case I915_SQS_PREEMPTED:
+	return "Preempted";
+
 	case I915_SQS_COMPLETE:
 	return "Complete";
 
diff --git a/drivers/gpu/drm/i915/i915_params.c b/drivers/gpu/drm/i915/i915_params.c
index f10482d06864..7d93b5b9d12c 100644
--- a/drivers/gpu/drm/i915/i915_params.c
+++ b/drivers/gpu/drm/i915/i915_params.c
@@ -59,6 +59,7 @@ struct i915_params i915 __read_mostly = {
 	.enable_dp_mst = true,
 	.inject_load_failure = 0,
 	.enable_scheduler = 1,
+	.enable_preemption = 0,
 };
 
 module_param_named(modeset, i915.modeset, int, 0400);
@@ -214,3 +215,6 @@ MODULE_PARM_DESC(inject_load_failure,
 
 module_param_named_unsafe(enable_scheduler, i915.enable_scheduler, int, 0600);
 MODULE_PARM_DESC(enable_scheduler, "Enable scheduler (0 = disable, 1 = enable [default])");
+
+module_param_named_unsafe(enable_preemption, i915.enable_preemption, int, 0600);
+MODULE_PARM_DESC(enable_preemption, "Enable pre-emption within scheduler  (0 = disable [default], 1 = enable)");
diff --git a/drivers/gpu/drm/i915/i915_params.h b/drivers/gpu/drm/i915/i915_params.h
index 44b08b3d5b90..6031b69493ad 100644
--- a/drivers/gpu/drm/i915/i915_params.h
+++ b/drivers/gpu/drm/i915/i915_params.h
@@ -51,6 +51,7 @@ struct i915_params {
 	int edp_vswing;
 	unsigned int inject_load_failure;
 	int enable_scheduler;
+	int enable_preemption;
 	/* leave bools at the end to not create holes */
 	bool enable_hangcheck;
 	bool fastboot;
diff --git a/drivers/gpu/drm/i915/i915_scheduler.c b/drivers/gpu/drm/i915/i915_scheduler.c
index c74606520ebc..b2e1c386fb12 100644
--- a/drivers/gpu/drm/i915/i915_scheduler.c
+++ b/drivers/gpu/drm/i915/i915_scheduler.c
@@ -51,10 +51,13 @@ bool i915_scheduler_is_enabled(struct drm_device *dev)
 
 const char *i915_qe_state_str(struct i915_scheduler_queue_entry *node)
 {
+	uint32_t sched_flags = node->params.request->scheduler_flags;
 	static char	str[50];
 	char		*ptr = str;
 
 	*(ptr++) = node->bumped ? 'B' : '-',
+	*(ptr++) = (sched_flags & I915_REQ_SF_PREEMPT) ? 'P' : '-';
+	*(ptr++) = (sched_flags & I915_REQ_SF_WAS_PREEMPT) ? 'p' : '-';
 	*(ptr++) = i915_gem_request_completed(node->params.request) ? 'C' : '-';
 
 	*ptr = 0;
@@ -77,6 +80,12 @@ char i915_scheduler_queue_status_chr(enum i915_scheduler_queue_status status)
 	case I915_SQS_FLYING:
 	return 'F';
 
+	case I915_SQS_OVERTAKING:
+	return 'O';
+
+	case I915_SQS_PREEMPTED:
+	return 'P';
+
 	case I915_SQS_COMPLETE:
 	return 'C';
 
@@ -241,6 +250,7 @@ static void i915_scheduler_node_fly(struct i915_scheduler_queue_entry *node)
 	struct drm_i915_private *dev_priv = to_i915(node->params.dev);
 	struct i915_scheduler *scheduler = dev_priv->scheduler;
 	struct intel_engine_cs *engine = node->params.engine;
+	struct drm_i915_gem_request *req = node->params.request;
 
 	assert_scheduler_lock_held(scheduler);
 
@@ -253,7 +263,10 @@ static void i915_scheduler_node_fly(struct i915_scheduler_queue_entry *node)
 	 */
 	list_add(&node->link, &scheduler->node_queue[engine->id]);
 
-	node->status = I915_SQS_FLYING;
+	if (req->scheduler_flags & I915_REQ_SF_PREEMPT)
+		node->status = I915_SQS_OVERTAKING;
+	else
+		node->status = I915_SQS_FLYING;
 
 	scheduler->counts[engine->id].flying++;
 	trace_i915_scheduler_fly(engine, node);
@@ -858,7 +871,7 @@ int i915_scheduler_queue_execbuffer(struct i915_scheduler_queue_entry *qe)
 	struct i915_scheduler *scheduler = dev_priv->scheduler;
 	struct intel_engine_cs *engine = qe->params.engine;
 	struct i915_scheduler_queue_entry *node;
-	bool not_flying;
+	bool not_flying, want_preempt;
 	int i, e;
 	int incomplete;
 
@@ -939,6 +952,25 @@ int i915_scheduler_queue_execbuffer(struct i915_scheduler_queue_entry *qe)
 	not_flying = i915_scheduler_count_flying(scheduler, engine) <
 						 scheduler->min_flying;
 
+	want_preempt = node->priority >= scheduler->priority_level_preempt;
+
+	if (!i915.enable_preemption)
+		want_preempt = false;
+
+	/* Pre-emption is not yet implemented in non-execlist mode */
+	if (!i915.enable_execlists)
+		want_preempt = false;
+
+	/* Pre-emption is not yet implemented in non-GUC mode */
+	if (!i915.enable_guc_submission)
+		want_preempt = false;
+
+	if (want_preempt) {
+		node->params.request->scheduler_flags |=
+			I915_REQ_SF_WAS_PREEMPT | I915_REQ_SF_PREEMPT;
+		scheduler->stats[engine->id].preempts_queued++;
+	}
+
 	scheduler->counts[engine->id].queued++;
 	scheduler->stats[engine->id].queued++;
 
@@ -947,7 +979,7 @@ int i915_scheduler_queue_execbuffer(struct i915_scheduler_queue_entry *qe)
 
 	spin_unlock_irq(&scheduler->lock);
 
-	if (not_flying)
+	if (not_flying || want_preempt)
 		i915_scheduler_submit(engine);
 
 	return 0;