[PATCH v8 0/2] drm/xe: Reject unsafe PAT indices for CPU cached memory

[Jia Yao <jia.yao@intel.com>]

This series strengthens PAT index validation to reject unsafe
configurations for CPU cached memory, preventing cases where the GPU
may bypass CPU caches and observe stale or sensitive data.

Patch 1 enforces PAT validation for the madvise ioctl path, ensuring
XE_COH_NONE cannot be used on CPU cached buffers, including CPU address
mirror and userptr-backed memory.

Patch 2 applies the same validation to vm_bind, treating
DRM_XE_VM_BIND_FLAG_CPU_ADDR_MIRROR the same as MAP_USERPTR with respect
to permissible PAT indices.

Together, these patches close a security gap affecting CPU cached
memory access when incoherent PAT values are used.

v9:
- Limit the restrictions to iGPU

Changes since v7:
- Rebased onto latest drm/xe tree, no functional changes.

Changes since v6:
- Corrected Fixes tags.

Fixes: ada7486c5668 ("drm/xe: Implement madvise ioctl for xe")
Fixes: b43e864af0d4 ("drm/xe/uapi: Add DRM_XE_VM_BIND_FLAG_CPU_ADDR_MIRROR")
Cc: stable@vger.kernel.org # v6.18
Cc: Shuicheng Lin <shuicheng.lin@intel.com>
Cc: Mathew Alwin <alwin.mathew@intel.com>
Cc: Michal Mrozek <michal.mrozek@intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Matthew Auld <matthew.auld@intel.com>

Jia Yao (2):
  drm/xe/uapi: Reject coh_none PAT index for CPU cached memory in
    madvise
  drm/xe: Reject coh_none PAT index for CPU_ADDR_MIRROR

 drivers/gpu/drm/xe/xe_vm.c         |  2 +-
 drivers/gpu/drm/xe/xe_vm_madvise.c | 45 ++++++++++++++++++++++++++++++
 2 files changed, 46 insertions(+), 1 deletion(-)

-- 
2.43.0