[PATCH v3 0/4] drm/xe/xe_migrate: Fix memory corruption with unaligned dst in MEM_COPY

[Jan Maslak <jan.maslak@intel.com>]

MEM_COPY_CMD in MATRIX_COPY mode produces incorrect results when the
destination address is not aligned to the pitch. This manifests as
memory corruption during xe_migrate_access_memory() reads from VRAM.

The probable cause appears to be a hardware requirement that the
destination address must be aligned to the pitch when using MATRIX_COPY
mode.

This was observed on BMG during xe_migrate_access_memory() calls where
the destination offset within a page was not aligned to the computed
pitch value.

Patch 1 adds the minimal workaround by selecting a pitch that is aligned
to both the copy length and the destination address.

Patch 2 fixes an independent page tracking bug in
xe_migrate_access_memory().

Patch 3 adds a follow-up optimization to reduce the number of linear
copy jobs for unaligned destinations.

Patch 4 adds a KUnit live test that exercises xe_migrate_access_memory()
with various unaligned destination offsets to prevent regressions.

Tested on BMG (Battlemage).

v2:
 - Split the original xe_migrate change into a minimal workaround,
   a standalone page tracking fix, and a follow-up optimization
   per Matthew Auld's review feedback
v3:
 - Used a helper function and added an additional comment in patch 3
   per Matthew Auld's review feedback

Christoph Manszewski (2):
  drm/xe/xe_migrate: Align MEM_COPY pitch with destination address
  drm/xe/xe_migrate: Fix page tracking in access_memory

Jan Maslak (2):
  drm/xe/xe_migrate: Optimize unaligned access_memory copies
  drm/xe/tests: Add xe_migrate_access_memory subtest

 drivers/gpu/drm/xe/tests/xe_migrate.c | 278 ++++++++++++++++++++++++++
 drivers/gpu/drm/xe/xe_migrate.c       | 176 ++++++++++++++--
 2 files changed, 435 insertions(+), 19 deletions(-)

-- 
2.43.0