drm/i915: Don't use stolen memory for ring buffers with LLC

Direction from hardware is that stolen memory should never be used for
ring buffer allocations on platforms with LLC. There are too many
caching pitfalls due to the way stolen memory accesses are routed. So
it is safest to just not use it.

Signed-off-by: John Harrison <[email protected]>
Fixes: c58b735fc762 ("drm/i915: Allocate rings from stolen")
Cc: Chris Wilson <[email protected]>
Cc: Joonas Lahtinen <[email protected]>
Cc: Jani Nikula <[email protected]>
Cc: Rodrigo Vivi <[email protected]>
Cc: Tvrtko Ursulin <[email protected]>
Cc: [email protected]
Cc: <[email protected]> # v4.9+
Tested-by: Jouni Högander <[email protected]>
Reviewed-by: Daniele Ceraolo Spurio <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]
(cherry picked from commit f54c1f6c697c4297f7ed94283c184acc338a5cf8)
Signed-off-by: Jani Nikula <[email protected]>

1 files changed, 1 insertions, 1 deletions

diff --git a/drivers/gpu/drm/i915/gt/intel_ring.c b/drivers/gpu/drm/i915/gt/intel_ring.c
index 15ec64d881c4..fb1d2595392e 100644
--- a/drivers/gpu/drm/i915/gt/intel_ring.c
+++ b/drivers/gpu/drm/i915/gt/intel_ring.c
@@ -116,7 +116,7 @@ static struct i915_vma *create_ring_vma(struct i915_ggtt *ggtt, int size)
 
 	obj = i915_gem_object_create_lmem(i915, size, I915_BO_ALLOC_VOLATILE |
 					  I915_BO_ALLOC_PM_VOLATILE);
-	if (IS_ERR(obj) && i915_ggtt_has_aperture(ggtt))
+	if (IS_ERR(obj) && i915_ggtt_has_aperture(ggtt) && !HAS_LLC(i915))
 		obj = i915_gem_object_create_stolen(i915, size);
 	if (IS_ERR(obj))
 		obj = i915_gem_object_create_internal(i915, size);