diff --git a/OvmfPkg/Library/LockBoxLib/LockBoxLib.c b/OvmfPkg/Library/LockBoxLib/LockBoxLib.c
index 45481b9230..04233059f1 100644
--- a/OvmfPkg/Library/LockBoxLib/LockBoxLib.c
+++ b/OvmfPkg/Library/LockBoxLib/LockBoxLib.c
@@ -3,7 +3,7 @@
   Library implementing the LockBox interface for OVMF
 
   Copyright (C) 2013, Red Hat, Inc.
-  Copyright (c) 2010 - 2014, Intel Corporation. All rights reserved.<BR>
+  Copyright (c) 2010 - 2019, Intel Corporation. All rights reserved.<BR>
 
   This program and the accompanying materials are licensed and made available
   under the terms and conditions of the BSD License which accompanies this
@@ -224,8 +224,13 @@ SetLockBoxAttributes (
   @retval RETURN_INVALID_PARAMETER  the Guid is NULL, or Buffer is NULL, or
                                     Length is 0.
   @retval RETURN_NOT_FOUND          the requested GUID not found.
-  @retval RETURN_BUFFER_TOO_SMALL   the original buffer to too small to hold
-                                    new information.
+  @retval RETURN_BUFFER_TOO_SMALL   for lockbox without attribute
+                                    LOCK_BOX_ATTRIBUTE_RESTORE_IN_S3_ONLY, the
+                                    original buffer to too small to hold new
+                                    information.
+  @retval RETURN_OUT_OF_RESOURCES   for lockbox with attribute
+                                    LOCK_BOX_ATTRIBUTE_RESTORE_IN_S3_ONLY, no
+                                    enough resource to save the information.
   @retval RETURN_ACCESS_DENIED      it is too late to invoke this interface
   @retval RETURN_NOT_STARTED        it is too early to invoke this interface
   @retval RETURN_UNSUPPORTED        the service is not supported by