On non-LLC platforms, force the flush-on-acquire if this is ever
swapped-in. Our async flush path is not trust worthy enough yet(and
happens in the wrong order), and with some tricks it's conceivable for
userspace to change the cache-level to I915_CACHE_NONE after the pages
are swapped-in, and since execbuf binds the object before doing the
async flush, there is a potential race window.
Signed-off-by: Matthew Auld <matthew.auld@xxxxxxxxx>
Cc: Thomas Hellström <thomas.hellstrom@xxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/gem/i915_gem_shmem.c | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
index cf11aa7e08a0..d77da59fae04 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
@@ -286,6 +286,8 @@ __i915_gem_object_release_shmem(struct drm_i915_gem_object *obj,
struct sg_table *pages,
bool needs_clflush)
{
+ struct drm_i915_private *i915 = to_i915(obj->base.dev);
+
GEM_BUG_ON(obj->mm.madv == __I915_MADV_PURGED);
if (obj->mm.madv == I915_MADV_DONTNEED)
@@ -297,6 +299,16 @@ __i915_gem_object_release_shmem(struct drm_i915_gem_object *obj,
drm_clflush_sg(pages);
__start_cpu_write(obj);
+ /*
+ * On non-LLC platforms, force the flush-on-acquire if this is ever
+ * swapped-in. Our async flush path is not trust worthy enough yet(and
+ * happens in the wrong order), and with some tricks it's conceivable
+ * for userspace to change the cache-level to I915_CACHE_NONE after the
+ * pages are swapped-in, and since execbuf binds the object before doing
+ * the async flush, we have a race window.
+ */
+ if (!HAS_LLC(i915))
+ obj->cache_dirty = true;
}
void i915_gem_object_put_pages_shmem(struct drm_i915_gem_object *obj, struct sg_table *pages)
--
2.26.3
