Index: /trunk/src/VBox/VMM/VMMR3/CPUM.cpp
===================================================================
--- /trunk/src/VBox/VMM/VMMR3/CPUM.cpp	(revision 68340)
+++ /trunk/src/VBox/VMM/VMMR3/CPUM.cpp	(revision 68341)
@@ -1269,5 +1269,6 @@
      */
     /* SVM. */
-    memset(pCtx->hwvirt.svm.CTX_SUFF(pVmcb), 0, sizeof(SVMVMCB));
+    if (pCtx->hwvirt.svm.CTX_SUFF(pVmcb))
+        memset(pCtx->hwvirt.svm.CTX_SUFF(pVmcb), 0, SVM_VMCB_PAGES << PAGE_SHIFT);
     pCtx->hwvirt.svm.uMsrHSavePa = 0;
     pCtx->hwvirt.svm.GCPhysVmcb = 0;