diff -aur xen-4.1.3.orig/xen/arch/x86/mm.c xen-4.1.3/xen/arch/x86/mm.c
--- xen-4.1.3.orig/xen/arch/x86/mm.c	2014-12-05 14:24:41.772853843 +0100
+++ xen-4.1.3/xen/arch/x86/mm.c	2014-12-05 14:26:17.177871063 +0100
@@ -3677,6 +3677,10 @@
         {
             p2m_type_t p2mt;
 
+            rc = -EOPNOTSUPP;
+            if ( unlikely(paging_mode_refcounts(pt_owner)) )
+                break;
+
             rc = xsm_mmu_normal_update(d, pg_owner, req.val);
             if ( rc )
                 break;
Nur in xen-4.1.3/xen/arch/x86: mm.c~.
