[Intel-gfx] [PATCH] drm/i915: Disable semaphore on vGPU for now

[Zhenyu Wang]

This is to disable semaphore usage when on vGPU for now. Unfortunately
GVT-g hasn't fully enabled semaphore usage yet, so current guest with
semaphore use would cause vGPU failure.

Although current semaphore failure with vGPU can be simply resolved by
allowing cmd parser to accept MI_SEMAPHORE_WAIT command with address
audit, we're checking general usage of semaphore and how we should
handle it properly for virtualization in consider of function and
security concern. So we decide to request to disable it for now in
guest driver. Once GVT could support it, we would add new compat bit
to turn it on.

Cc: Kevin Tian <kevin.tian at intel.com>
Cc: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw at linux.intel.com>
---
Note this needs to queue for -next otherwise next kernel i915 as guest
would be broken for GVT.

 drivers/gpu/drm/i915/intel_lrc.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 66bc3cd4e166..50075e24ae03 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -2315,7 +2315,8 @@ void intel_execlists_set_default_submission(struct intel_engine_cs *engine)
 	engine->park = NULL;
 	engine->unpark = NULL;
 
-	engine->flags |= I915_ENGINE_HAS_SEMAPHORES;
+	if (!intel_vgpu_active(engine->i915))
+		engine->flags |= I915_ENGINE_HAS_SEMAPHORES;
 	engine->flags |= I915_ENGINE_SUPPORTS_STATS;
 	if (engine->preempt_context)
 		engine->flags |= I915_ENGINE_HAS_PREEMPTION;
-- 
2.20.1