From: Jia Yao <jia.yao@intel.com>
Date: Fri, 17 Apr 2026 05:59:17 +0000 (+0000)
Subject: drm/xe/uapi: Reject coh_none PAT index for CPU_ADDR_MIRROR
X-Git-Tag: v7.1-rc2~7^2^2
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=662f9ddc8077792129440d05cbef2f944a07777a;p=thirdparty%2Fkernel%2Flinux.git

drm/xe/uapi: Reject coh_none PAT index for CPU_ADDR_MIRROR

Add validation in xe_vm_bind_ioctl() to reject PAT indices
with XE_COH_NONE coherency mode when used with
DRM_XE_VM_BIND_FLAG_CPU_ADDR_MIRROR.

CPU address mirror mappings use system memory that is CPU
cached, which makes them incompatible with COH_NONE PAT
indices. Allowing COH_NONE with CPU cached buffers is a
security risk, as the GPU may bypass CPU caches and read
stale sensitive data from DRAM.

Although CPU_ADDR_MIRROR does not create an immediate
mapping, the backing system memory is still CPU cached.
Apply the same PAT coherency restrictions as
DRM_XE_VM_BIND_OP_MAP_USERPTR.

v2:
- Correct fix tag

v6:
- No change

v7:
- Correct fix tag

v8:
- Rebase

v9:
- Limit the restrictions to iGPU

v10:
- Just add the iGPU logic but keep dGPU logic

Fixes: b43e864af0d4 ("drm/xe/uapi: Add DRM_XE_VM_BIND_FLAG_CPU_ADDR_MIRROR")
Cc: <stable@vger.kernel.org> # v6.15+
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>
Signed-off-by: Jia Yao <jia.yao@intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Acked-by: Michal Mrozek <michal.mrozek@intel.com>
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patch.msgid.link/20260417055917.2027459-3-jia.yao@intel.com
(cherry picked from commit 4d58d7535e826a3175527b6174502f0db319d7f6)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
---

diff --git a/drivers/gpu/drm/xe/xe_vm.c b/drivers/gpu/drm/xe/xe_vm.c
index 1720205c09ca..a717a2b8dea3 100644
--- a/drivers/gpu/drm/xe/xe_vm.c
+++ b/drivers/gpu/drm/xe/xe_vm.c
@@ -3658,6 +3658,8 @@ static int vm_bind_ioctl_check_args(struct xe_device *xe, struct xe_vm *vm,
 				 op == DRM_XE_VM_BIND_OP_MAP_USERPTR) ||
 		    XE_IOCTL_DBG(xe, coh_mode == XE_COH_NONE &&
 				 op == DRM_XE_VM_BIND_OP_MAP_USERPTR) ||
+		    XE_IOCTL_DBG(xe, !IS_DGFX(xe) && coh_mode == XE_COH_NONE &&
+				 is_cpu_addr_mirror) ||
 		    XE_IOCTL_DBG(xe, xe_device_is_l2_flush_optimized(xe) &&
 				 (op == DRM_XE_VM_BIND_OP_MAP_USERPTR ||
 				  is_cpu_addr_mirror) &&