Index: /trunk/src/VBox/VMM/HWACCM.cpp
===================================================================
--- /trunk/src/VBox/VMM/HWACCM.cpp	(revision 10690)
+++ /trunk/src/VBox/VMM/HWACCM.cpp	(revision 10691)
@@ -93,4 +93,9 @@
     if (VBOX_FAILURE(rc))
         return rc;
+
+    /* Check CFGM option. */
+    rc = CFGMR3QueryBool(CFGMR3GetRoot(pVM), "EnableNestedPaging", &pVM->hwaccm.s.fAllowNestedPaging);
+    if (VBOX_FAILURE(rc))
+        pVM->hwaccm.s.fAllowNestedPaging = true;    /* enabled by default now. */
 
     /* Misc initialisation. */
@@ -504,8 +509,6 @@
             pVM->hwaccm.s.fInitialized = true;
 
-#ifdef VBOX_WITH_NESTED_PAGING
             if (pVM->hwaccm.s.svm.u32Features & AMD_CPUID_SVM_FEATURE_EDX_NESTED_PAGING)
-                pVM->hwaccm.s.fNestedPaging = true;
-#endif
+                pVM->hwaccm.s.fNestedPaging = pVM->hwaccm.s.fAllowNestedPaging;
 
             rc = SUPCallVMMR0Ex(pVM->pVMR0, VMMR0_DO_HWACC_SETUP_VM, 0, NULL);
Index: /trunk/src/VBox/VMM/HWACCMInternal.h
===================================================================
--- /trunk/src/VBox/VMM/HWACCMInternal.h	(revision 10690)
+++ /trunk/src/VBox/VMM/HWACCMInternal.h	(revision 10691)
@@ -34,6 +34,4 @@
 #include <iprt/mp.h>
 
-/* Uncomment to enable experimental nested paging. */
-/////#define VBOX_WITH_NESTED_PAGING
 #if HC_ARCH_BITS == 64
 /* Enable 64 bits guest support. */
@@ -177,4 +175,7 @@
     /** Set if nested paging is enabled. */
     bool                        fNestedPaging;
+
+    /** Set if nested paging is allowed. */
+    bool                        fAllowNestedPaging;
 
     /** HWACCM_CHANGED_* flags. */