On 2/15/2023 5:11 PM, John.C.Harrison@Intel.com wrote:

From: John Harrison John.C.Harrison@Intel.com

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 John.C.Harrison@Intel.com Fixes: c58b735fc762 ("drm/i915: Allocate rings from stolen") Cc: Chris Wilson chris@chris-wilson.co.uk Cc: Joonas Lahtinen joonas.lahtinen@linux.intel.com Cc: Jani Nikula jani.nikula@linux.intel.com Cc: Rodrigo Vivi rodrigo.vivi@intel.com Cc: Tvrtko Ursulin tvrtko.ursulin@linux.intel.com Cc: intel-gfx@lists.freedesktop.org Cc: stable@vger.kernel.org # v4.9+

Reviewed-by: Daniele Ceraolo Spurio daniele.ceraolospurio@intel.com

Daniele

---

drivers/gpu/drm/i915/gt/intel_ring.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/gt/intel_ring.c b/drivers/gpu/drm/i915/gt/intel_ring.c index 15ec64d881c44..fb1d2595392ed 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);