On 19/10/2022 08:12, Andrzej Hajda wrote:
Instruction prefetch mechanism requires that 512 bytes after the last
command should be readable by EU. Otherwise DMAR errors and engine
hangs can happen.
Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/5278
Signed-off-by: Andrzej Hajda <andrzej.hajda@xxxxxxxxx>
Is there a Bspec ref for this? I would have assumed that EU was more
about kernels/shaders, than simple MI commands? Also should we be
hitting dmar errors for ppGTT if this were some kind of overfetch?
AFAICT we always point entries back to scratch, unlike with say the GGTT
where we might have stale entries, and unbinding should flush the tlb?
---
drivers/gpu/drm/i915/gem/selftests/igt_gem_utils.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/gem/selftests/igt_gem_utils.c b/drivers/gpu/drm/i915/gem/selftests/igt_gem_utils.c
index 3c55e77b0f1b00..fe999a02f8e10a 100644
--- a/drivers/gpu/drm/i915/gem/selftests/igt_gem_utils.c
+++ b/drivers/gpu/drm/i915/gem/selftests/igt_gem_utils.c
@@ -50,7 +50,7 @@ igt_emit_store_dw(struct i915_vma *vma,
u32 *cmd;
int err;
- size = (4 * count + 1) * sizeof(u32);
+ size = (4 * count + 1) * sizeof(u32) + 512;
size = round_up(size, PAGE_SIZE);
obj = i915_gem_object_create_internal(vma->vm->i915, size);
if (IS_ERR(obj))
