From eb119bd612906519cacef2536a9a524c2da5f7fb Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Sun, 16 Dec 2012 12:43:36 +0000 Subject: [PATCH] drm/i915: Access to snooped system memory through the GTT is incoherent 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 Signed-off-by: Daniel Vetter --- 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 6380c6083cb2..d15c86279d02 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -1341,6 +1341,12 @@ 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, true, false); if (ret) -- 2.20.1