drm/xe: Support device page faults on integrated platforms

Update xe_migrate_prepare_vm() to use the usm batch buffer even for
servicing device page faults on integrated platforms. And as we have
no VRAM on integrated platforms, device pagefault handler should not
attempt to migrate into VRAM.
LNL is first integrated platform to support device pagefaults.
Signed-off-by: Brian Welty <brian.welty@intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

drivers/gpu/drm/xe/xe_gt_pagefault.c

@@ -106,7 +106,7 @@ static int xe_pf_begin(struct drm_exec *exec, struct xe_vma *vma,
 	if (err)
 		return err;
 
-	if (atomic) {
+	if (atomic && IS_DGFX(vm->xe)) {
 		if (xe_vma_is_userptr(vma)) {
 			err = -EACCES;
 			return err;

drivers/gpu/drm/xe/xe_migrate.c

@@ -215,10 +215,13 @@ static int xe_migrate_prepare_vm(struct xe_tile *tile, struct xe_migrate *m,
 	}
 
 	if (!IS_DGFX(xe)) {
-		xe_tile_assert(tile, !xe->info.supports_usm);
-
 		/* Write out batch too */
 		m->batch_base_ofs = NUM_PT_SLOTS * XE_PAGE_SIZE;
+		if (xe->info.supports_usm) {
+			batch = tile->primary_gt->usm.bb_pool->bo;
+			m->usm_batch_base_ofs = m->batch_base_ofs;
+		}
+
 		for (i = 0; i < batch->size;
 		     i += vm->flags & XE_VM_FLAG_64K ? XE_64K_PAGE_SIZE :
 		     XE_PAGE_SIZE) {