drm/xe/mmio_gem: use write-back mapping for dummy page

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Currently vmf_insert_pfn() maps the dummy page as UC, inheriting the
VMA's page protection which was set for the real MMIO region. This
conflicts with the direct map's WB mapping of the same page, creating a
cache type alias which is architecturally undefined on some platforms.

Use vmf_insert_pfn_prot() with a WB pgprot instead. Also simplify to
fault in the requested page instead of the whole VMA.

Fixes: 1ffcf8b8ae ("drm/xe: Support for mmap-ing mmio regions")
Reported-by: Sashiko <sashiko-bot@kernel.org>
Closes: https://sashiko.dev/#/patchset/20260525125801.975038-6-ilia.levi%40intel.com
Assisted-by: GitHub-Copilot:claude-opus-4.6
Signed-off-by: Ilia Levi <ilia.levi@intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patch.msgid.link/20260908165046.1393557-12-matthew.auld@intel.com

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Ilia Levi 2026-09-08 17:50:49 +01:00 • committed by Matthew Auld

parent f3391a0b12

commit 1e8e28e35d

1 changed files with 5 additions and 14 deletions

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drivers/gpu/drm/xe/xe_mmio_gem.c

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