[PATCH v2] UefiCpuPkg\CpuSmm: Save & restore CR2 on-demand paging in SMM

[nkvangup <narendra.k.vanguput@intel.com>]

BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=1593

For every SMI occurrence, save and restore CR2 register only when SMM
on-demand paging support is enabled in 64 bit operation mode.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Vanguput Narendra K <narendra.k.vanguput@intel.com>
Cc: Eric Dong <eric.dong@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Yao Jiewen <jiewen.yao@intel.com>
---
 UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c | 20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c b/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c
index 3b0b3b52ac..5be4a2b020 100644
--- a/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c
+++ b/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c
@@ -1111,10 +1111,12 @@ SmiRendezvous (
 
   ASSERT(CpuIndex < mMaxNumberOfCpus);
 
-  //
-  // Save Cr2 because Page Fault exception in SMM may override its value
-  //
-  Cr2 = AsmReadCr2 ();
+  if ((sizeof (UINTN) == sizeof (UINT64)) && (!PcdGetBool (PcdCpuSmmStaticPageTable))) {
+    //
+    // Save Cr2 because Page Fault exception in SMM may override its value
+    //
+    Cr2 = AsmReadCr2 ();
+  }
 
   //
   // Perform CPU specific entry hooks
@@ -1253,10 +1255,12 @@ SmiRendezvous (
 
 Exit:
   SmmCpuFeaturesRendezvousExit (CpuIndex);
-  //
-  // Restore Cr2
-  //
-  AsmWriteCr2 (Cr2);
+  if ((sizeof (UINTN) == sizeof (UINT64)) && (!PcdGetBool (PcdCpuSmmStaticPageTable))) {
+    //
+    // Restore Cr2
+    //
+    AsmWriteCr2 (Cr2);
+  }
 }
 
 /**
-- 
2.16.2.windows.1