Claude review: drm/xe/uapi: Define drm_xe_vm_get_property

[Claude Code Review Bot <claude-review@example.com>]

Patch Review

**uAPI naming convention issue**: The `struct xe_vm_fault` and defines like `FAULT_ACCESS_TYPE_READ`, `FAULT_TYPE_NOT_PRESENT`, `FAULT_LEVEL_PTE` don't follow the `drm_xe_` / `DRM_XE_` naming convention used everywhere else in `xe_drm.h`. These generic names risk collisions with other kernel/userspace headers. They should be:
- `struct drm_xe_vm_fault`
- `DRM_XE_VM_FAULT_ACCESS_TYPE_READ` (etc.)
- `DRM_XE_VM_FAULT_TYPE_NOT_PRESENT` (etc.)
- `DRM_XE_VM_FAULT_LEVEL_PTE` (etc.)

**Missing `pad` MBZ validation in struct docs**: The `pad` field in `struct xe_vm_fault` is documented as MBZ. The ioctl handler (patch 4) never validates that `pad` is zero on output, nor does it validate `extensions` in `struct drm_xe_vm_get_property`. These should be checked to preserve forward compatibility.

**Struct size**: `struct xe_vm_fault` is `8 + 4 + 1 + 1 + 1 + 1 + 32 = 48` bytes, which is nicely aligned. The `reserved[4]` provides 32 bytes for future expansion which seems generous.

The two-phase size query / data fetch pattern is a reasonable approach for the ioctl design.

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Generated by Claude Code Patch Reviewer