drm/xe/svm: Support DRM_XE_SVM_MEM_RANGE_ATTR_PAT memory attribute

This attributes sets the pat_index for the svm used vma range, which is
utilized to ascertain the coherence.

v2 (Matthew Brost)
- Pat index sanity check

Cc: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Link: https://lore.kernel.org/r/20250821173104.3030148-12-himal.prasad.ghimiray@intel.com
Signed-off-by: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>

drivers/gpu/drm/xe/xe_vm_madvise.c

@@ -9,6 +9,7 @@
 #include <drm/xe_drm.h>
 
 #include "xe_bo.h"
+#include "xe_pat.h"
 #include "xe_pt.h"
 #include "xe_svm.h"
 
@@ -121,7 +122,12 @@ static void madvise_pat_index(struct xe_device *xe, struct xe_vm *vm,
 			      struct xe_vma **vmas, int num_vmas,
 			      struct drm_xe_madvise *op)
 {
-	/* Implementation pending */
+	int i;
+
+	xe_assert(vm->xe, op->type == DRM_XE_MEM_RANGE_ATTR_PAT);
+
+	for (i = 0; i < num_vmas; i++)
+		vmas[i]->attr.pat_index = op->pat_index.val;
 }
 
 typedef void (*madvise_func)(struct xe_device *xe, struct xe_vm *vm,
@@ -229,8 +235,22 @@ static bool madvise_args_are_sane(struct xe_device *xe, const struct drm_xe_madv
 
 		break;
 	case DRM_XE_MEM_RANGE_ATTR_PAT:
-		/*TODO: Add valid pat check */
+	{
+		u16 coh_mode = xe_pat_index_get_coh_mode(xe, args->pat_index.val);
+
+		if (XE_IOCTL_DBG(xe, !coh_mode))
+			return false;
+
+		if (XE_WARN_ON(coh_mode > XE_COH_AT_LEAST_1WAY))
+			return false;
+
+		if (XE_IOCTL_DBG(xe, args->pat_index.pad))
+			return false;
+
+		if (XE_IOCTL_DBG(xe, args->pat_index.reserved))
+			return false;
 		break;
+	}
 	default:
 		if (XE_IOCTL_DBG(xe, 1))
 			return false;