We ignore all the user requests to handle flushing to the GTT domain if
the user requests such on a snoopable bo, and as such access through the
GTT to such pages remains incoherent. The specs even warn that such
behaviour is undefined - a strong reason never to do so.
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
drivers/gpu/drm/i915/i915_gem.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 65cf019..6438b2c 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1417,6 +1417,12 @@ int i915_gem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
trace_i915_gem_object_fault(obj, page_offset, true, write);
+ /* Access to snoopable pages through the GTT is incoherent. */
+ if (obj->cache_level != I915_CACHE_NONE && !HAS_LLC(dev)) {
+ ret = -EINVAL;
+ goto unlock;
+ }
+
/* Now bind it into the GTT if needed */
ret = i915_gem_object_pin(obj, 0, I915_PIN_MAPPABLE);
if (ret)
--
1.7.10.4
