diff -r ef514a30fd70 xen/arch/x86/hvm/svm/nestedsvm.c
--- a/xen/arch/x86/hvm/svm/nestedsvm.c	Fri Sep 21 13:25:22 2012 +0200
+++ b/xen/arch/x86/hvm/svm/nestedsvm.c	Fri Sep 21 14:44:13 2012 +0200
@@ -745,6 +745,11 @@ nsvm_vcpu_vmrun(struct vcpu *v, struct c
         return 1;
     }
 
+    /* If we use nested paging and l1 guest uses shadow paging ... */
+    if (paging_mode_hap(v->domain) && !nestedhvm_paging_mode_hap(v))
+        /* ... update the paging modes. */
+        paging_update_paging_modes(v);
+
     nv->nv_vmswitch_in_progress = 0;
     return 0;
 }
@@ -1412,6 +1417,11 @@ nestedsvm_vcpu_vmexit(struct vcpu *v, st
      */
     rc = nhvm_vcpu_vmexit(v, regs, exitcode);
 
+    /* If we use nested paging and l1 guest uses shadow paging ... */
+    if (paging_mode_hap(v->domain) && !nestedhvm_paging_mode_hap(v))
+        /* ... update the paging modes. */
+        paging_update_paging_modes(v);
+
     nv->nv_vmswitch_in_progress = 0;
 
     if (rc)