[PATCH 1/3] drm/i915/execlists: Disable preemption under GVT

[Chris Wilson]

Preempt-to-busy uses a GPU semaphore to enforce an idle-barrier across
preemption, but mediated gvt does not fully support semaphores.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/gt/intel_lrc.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c
index c8a0c9b32764..d8649e759ce8 100644
--- a/drivers/gpu/drm/i915/gt/intel_lrc.c
+++ b/drivers/gpu/drm/i915/gt/intel_lrc.c
@@ -294,6 +294,9 @@ static inline bool need_preempt(const struct intel_engine_cs *engine,
 {
 	int last_prio;
 
+	if (!intel_engine_has_preemption(engine))
+		return false;
+
 	/*
 	 * Check if the current priority hint merits a preemption attempt.
 	 *
@@ -890,6 +893,9 @@ need_timeslice(struct intel_engine_cs *engine, const struct i915_request *rq)
 {
 	int hint;
 
+	if (!intel_engine_has_preemption(engine))
+		return false;
+
 	if (list_is_last(&rq->sched.link, &engine->active.requests))
 		return false;
 
@@ -2672,10 +2678,11 @@ void intel_execlists_set_default_submission(struct intel_engine_cs *engine)
 	engine->unpark = NULL;
 
 	engine->flags |= I915_ENGINE_SUPPORTS_STATS;
-	if (!intel_vgpu_active(engine->i915))
+	if (!intel_vgpu_active(engine->i915)) {
 		engine->flags |= I915_ENGINE_HAS_SEMAPHORES;
-	if (HAS_LOGICAL_RING_PREEMPTION(engine->i915))
-		engine->flags |= I915_ENGINE_HAS_PREEMPTION;
+		if (HAS_LOGICAL_RING_PREEMPTION(engine->i915))
+			engine->flags |= I915_ENGINE_HAS_PREEMPTION;
+	}
 }
 
 static void execlists_destroy(struct intel_engine_cs *engine)
-- 
2.20.1