Claude review: drm/xe/uapi: Define drm_xe_vm_get_property

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

Patch Review

**uAPI naming concern:** The `struct xe_vm_fault` does not follow the `drm_xe_` prefix convention used by all other uAPI structs in this header (e.g., `drm_xe_vm_create`, `drm_xe_vm_bind`). Similarly, the `FAULT_ACCESS_TYPE_*`, `FAULT_TYPE_*`, and `FAULT_LEVEL_*` defines lack a `DRM_XE_` prefix, which risks namespace collisions. Every other define in this header uses `DRM_XE_` prefixing. This is a uAPI that will be set in stone once merged — the naming should be consistent.

**Struct padding/alignment:** `struct xe_vm_fault` has `__u64 address`, then `__u32 address_precision`, then three `__u8` fields, then one `__u8 pad`, then `__u64 reserved[4]`. Between `pad` and `reserved` there are 0 bytes of implicit padding since the three u8 + pad = 4 bytes, and address_precision (u32) + 4 bytes of u8s = 8 bytes after the u64, so alignment is fine. Good.

**`data`/`value` union:** The union of `data` and `value` in `drm_xe_vm_get_property` is reasonable for supporting both pointer and scalar property types, though currently only `data` (pointer) is used.

**Size field is `__u32`:** The `size` field is `__u32`, which limits the maximum reportable faults. With `sizeof(struct xe_vm_fault)` being 48 bytes and MAX_FAULTS_SAVED_PER_VM=50, the max is 2400 bytes — well within `__u32` range. Fine, but somewhat inconsistent with other ioctls that use `__u64` for sizes.

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