Get rid of boot services code after exiting boot services

xtldr/amd64/memory.c

@@ -149,6 +149,10 @@ BlEnablePaging(IN PLIST_ENTRY MemoryMappings,
     BlDbgPrint(L"Exiting EFI boot services\n");
     EfiSystemTable->BootServices->ExitBootServices(EfiImageHandle, MemoryMap->MapKey);
 
+    /* No runtime services should touch boot services code, so get rid of it all at this point */
+    EfiSystemTable->RuntimeServices->SetVirtualAddressMap(MemoryMap->MapSize, MemoryMap->DescriptorSize,
+                                                          MemoryMap->DescriptorVersion, MemoryMap->Map);
+
     /* Write PML4 to CR3 */
     HlWriteCR3((UINT_PTR)*PtePointer);