Index: /trunk/src/VBox/VMM/VMMSwitcher/LegacyandAMD64.mac
===================================================================
--- /trunk/src/VBox/VMM/VMMSwitcher/LegacyandAMD64.mac	(revision 48248)
+++ /trunk/src/VBox/VMM/VMMSwitcher/LegacyandAMD64.mac	(revision 48249)
@@ -429,13 +429,6 @@
     mov     eax, cr3
     mov     [edx + CPUMCPU.Host.cr3], eax
-    mov     eax, cr4
-    mov     [edx + CPUMCPU.Host.cr4], eax
-%if 0 ; paranoia
-    test    eax, X86_CR4_VMXE
-    jz      .vmxe_fine
-    mov     eax, VERR_VMX_IN_VMX_ROOT_MODE
-    retf
-.vmxe_fine:
-%endif
+    mov     esi, cr4                      ; esi = cr4, we'll modify it further down.
+    mov     [edx + CPUMCPU.Host.cr4], esi
 
     DEBUG32_S_CHAR('c')
@@ -467,4 +460,12 @@
 
     ;;
+    ;; Clean up CR4.  X86_CR4_PGE, X86_CR4_PCE, X86_CR4_PCIDE (not really
+    ;; relevant for 32-bit, but whatever) and X86_CR4_VMXE must be cleared.
+    ;;
+    and     esi, X86_CR4_VME | X86_CR4_PVI | X86_CR4_TSD | X86_CR4_DE | X86_CR4_PSE | X86_CR4_PAE \
+               | X86_CR4_MCE | X86_CR4_OSFSXR | X86_CR4_OSXMMEEXCPT | X86_CR4_SMXE | X86_CR4_OSXSAVE
+    mov     cr4, esi
+
+    ;;
     ;; Load Intermediate memory context.
     ;;
@@ -475,10 +476,4 @@
 %ifdef VBOX_WITH_64ON32_CMOS_DEBUG
     DEBUG_CMOS_TRASH_AL 17h
-    jmp     .first_jmp
-    times 65 db 90h
-.first_jmp:
-    times 65 db 90h
-.second_jmp:
-    DEBUG_CMOS_TRASH_AL 18h
 %endif