drm/xe: Take a ref to xe file when user creates a VM

Take a reference to xef when user creates the VM and put the reference
when user destroys the VM.

Signed-off-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240718210548.3580382-4-umesh.nerlige.ramappa@intel.com
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>

drivers/gpu/drm/xe/xe_vm.c

@@ -1670,6 +1670,10 @@ static void vm_destroy_work_func(struct work_struct *w)
 		XE_WARN_ON(vm->pt_root[id]);
 
 	trace_xe_vm_free(vm);
+
+	if (vm->xef)
+		xe_file_put(vm->xef);
+
 	kfree(vm);
 }
 
@@ -1802,7 +1806,7 @@ int xe_vm_create_ioctl(struct drm_device *dev, void *data,
 	}
 
 	args->vm_id = id;
-	vm->xef = xef;
+	vm->xef = xe_file_get(xef);
 
 	/* Record BO memory for VM pagetable created against client */
 	for_each_tile(tile, xe, id)