[Intel-gfx] [PATCH v2 1/2] drm/i915/gtt: flush the scratch page

[Matthew Auld <matthew.auld@intel.com>]

The scratch page is directly visible in the users address space, and
while this is forced as CACHE_LLC, by the kernel, we still have to
contend with things like "Bypass-LLC" MOCS. So just flush no matter
what.

v2(Thomas):
  - Make sure we use drm_clflush_virt_range here, in case clflush support
    is missing.

Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Ramalingam C <ramalingam.c@intel.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
---
 drivers/gpu/drm/i915/gt/intel_gtt.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/i915/gt/intel_gtt.c b/drivers/gpu/drm/i915/gt/intel_gtt.c
index 67d14afa6623..efb51e881c5a 100644
--- a/drivers/gpu/drm/i915/gt/intel_gtt.c
+++ b/drivers/gpu/drm/i915/gt/intel_gtt.c
@@ -273,6 +273,7 @@ static void poison_scratch_page(struct drm_i915_gem_object *scratch)
 		val = POISON_FREE;
 
 	memset(vaddr, val, scratch->base.size);
+	drm_clflush_virt_range(vaddr, scratch->base.size);
 }
 
 int setup_scratch_page(struct i915_address_space *vm)
-- 
2.26.3