On 10/22/21 18:48, Matthew Auld wrote:
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.

Signed-off-by: Matthew Auld <matthew.a...@intel.com>
Cc: Thomas Hellström <thomas.hellst...@linux.intel.com>
Cc: Chris Wilson <ch...@chris-wilson.co.uk>
Cc: Ramalingam C <ramalinga...@intel.com>

Reviewed-by: Thomas Hellström <thomas.hellst...@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..b6c088423319 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);
+       clflush_cache_range(vaddr, scratch->base.size);
  }
int setup_scratch_page(struct i915_address_space *vm)

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