This is a note to let you know that I've just added the patch titled
drm/xe: Add mmio read before GGTT invalidate
to the 6.11-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
drm-xe-add-mmio-read-before-ggtt-invalidate.patch
and it can be found in the queue-6.11 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit ef77231ea76a679ce2c45b3633fc73d1968865ba
Author: Matthew Brost <matthew.brost@xxxxxxxxx>
Date: Wed Oct 23 15:12:00 2024 -0700
drm/xe: Add mmio read before GGTT invalidate
[ Upstream commit 993ca0eccec65a2cacc3cefb15d35ffadc6f00fb ]
On LNL without a mmio read before a GGTT invalidate the GuC can
incorrectly read the GGTT scratch page upon next access leading to jobs
not getting scheduled. A mmio read before a GGTT invalidate seems to fix
this. Since a GGTT invalidate is not a hot code path, blindly do a mmio
read before each GGTT invalidate.
Cc: John Harrison <John.C.Harrison@xxxxxxxxx>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@xxxxxxxxx>
Cc: Thomas Hellström <thomas.hellstrom@xxxxxxxxxxxxxxx>
Cc: Lucas De Marchi <lucas.demarchi@xxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Fixes: dd08ebf6c352 ("drm/xe: Introduce a new DRM driver for Intel GPUs")
Reported-by: Paulo Zanoni <paulo.r.zanoni@xxxxxxxxx>
Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/3164
Signed-off-by: Matthew Brost <matthew.brost@xxxxxxxxx>
Reviewed-by: Lucas De Marchi <lucas.demarchi@xxxxxxxxx>
Link: https://patchwork.freedesktop.org/patch/msgid/20241023221200.1797832-1-matthew.brost@xxxxxxxxx
Signed-off-by: Lucas De Marchi <lucas.demarchi@xxxxxxxxx>
(cherry picked from commit 5a710196883e0ac019ac6df2a6d79c16ad3c32fa)
[ Fix conflict with mmio vs gt argument ]
Signed-off-by: Lucas De Marchi <lucas.demarchi@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/gpu/drm/xe/xe_ggtt.c b/drivers/gpu/drm/xe/xe_ggtt.c
index 0cdbc1296e885..226542bb1442e 100644
--- a/drivers/gpu/drm/xe/xe_ggtt.c
+++ b/drivers/gpu/drm/xe/xe_ggtt.c
@@ -309,6 +309,16 @@ static void ggtt_invalidate_gt_tlb(struct xe_gt *gt)
static void xe_ggtt_invalidate(struct xe_ggtt *ggtt)
{
+ struct xe_device *xe = tile_to_xe(ggtt->tile);
+
+ /*
+ * XXX: Barrier for GGTT pages. Unsure exactly why this required but
+ * without this LNL is having issues with the GuC reading scratch page
+ * vs. correct GGTT page. Not particularly a hot code path so blindly
+ * do a mmio read here which results in GuC reading correct GGTT page.
+ */
+ xe_mmio_read32(xe_root_mmio_gt(xe), VF_CAP_REG);
+
/* Each GT in a tile has its own TLB to cache GGTT lookups */
ggtt_invalidate_gt_tlb(ggtt->tile->primary_gt);
ggtt_invalidate_gt_tlb(ggtt->tile->media_gt);
