UefiCpuPkg/CpuMpPei: Add GDT migration support (CVE-2019-11098)

REF:https://bugzilla.tianocore.org/show_bug.cgi?id=1614

Moves the GDT to permanent memory in a memory discovered
callback. This is done to ensure the GDT authenticated in
pre-memory is not fetched from outside a verified location
after the permanent memory transition.

Cc: Eric Dong <eric.dong@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Rahul Kumar <rahul1.kumar@intel.com>
Signed-off-by: Michael Kubacki <michael.a.kubacki@intel.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jian J Wang <jian.j.wang@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>

UefiCpuPkg/CpuMpPei/CpuPaging.c

@@ -602,8 +602,16 @@ MemoryDiscoveredPpiNotifyCallback (
   IN VOID                       *Ppi
   )
 {
-  EFI_STATUS      Status;
-  BOOLEAN         InitStackGuard;
+  EFI_STATUS  Status;
+  BOOLEAN     InitStackGuard;
+  BOOLEAN     InterruptState;
+
+  if (PcdGetBool (PcdMigrateTemporaryRamFirmwareVolumes)) {
+    InterruptState = SaveAndDisableInterrupts ();
+    Status = MigrateGdt ();
+    ASSERT_EFI_ERROR (Status);
+    SetInterruptState (InterruptState);
+  }
 
   //
   // Paging must be setup first. Otherwise the exception TSS setup during MP