diff --git a/UefiCpuPkg/CpuDxe/CpuDxe.c b/UefiCpuPkg/CpuDxe/CpuDxe.c
index ad4599dab9..c1eee028aa 100644
--- a/UefiCpuPkg/CpuDxe/CpuDxe.c
+++ b/UefiCpuPkg/CpuDxe/CpuDxe.c
@@ -23,7 +23,6 @@ EFI_CPU_INTERRUPT_HANDLER ExternalVectorTable[0x100];
 BOOLEAN                   InterruptState = FALSE;
 EFI_HANDLE                mCpuHandle = NULL;
 BOOLEAN                   mIsFlushingGCD;
-UINT8                     mDefaultMemoryType    = MTRR_CACHE_WRITE_BACK;
 UINT64                    mValidMtrrAddressMask = MTRR_LIB_CACHE_VALID_ADDRESS;
 UINT64                    mValidMtrrBitsMask    = MTRR_LIB_MSR_VALID_MASK;
 
@@ -715,7 +714,7 @@ InitializeMtrrMask (
 **/
 UINT64
 GetMemorySpaceAttributeFromMtrrType (
-  IN UINT8                MtrrAttributes
+  IN MTRR_MEMORY_CACHE_TYPE  MtrrAttributes
   )
 {
   switch (MtrrAttributes) {
@@ -880,13 +879,14 @@ RefreshGcdMemoryAttributes (
   UINT64                              Length;
   UINT64                              Attributes;
   UINT64                              CurrentAttributes;
-  UINT8                               MtrrType;
+  MTRR_MEMORY_CACHE_TYPE              MtrrType;
   UINTN                               NumberOfDescriptors;
   EFI_GCD_MEMORY_SPACE_DESCRIPTOR     *MemorySpaceMap;
   UINT64                              DefaultAttributes;
   VARIABLE_MTRR                       VariableMtrr[MTRR_NUMBER_OF_VARIABLE_MTRR];
   MTRR_FIXED_SETTINGS                 MtrrFixedSettings;
   UINT32                              FirmwareVariableMtrrCount;
+  MTRR_MEMORY_CACHE_TYPE              DefaultMemoryType;
 
   if (!IsMtrrSupported ()) {
     return;
@@ -895,8 +895,7 @@ RefreshGcdMemoryAttributes (
   FirmwareVariableMtrrCount = GetFirmwareVariableMtrrCount ();
   ASSERT (FirmwareVariableMtrrCount <= MTRR_NUMBER_OF_VARIABLE_MTRR);
 
-//  mIsFlushingGCD = TRUE;
-  mIsFlushingGCD = FALSE;
+  mIsFlushingGCD = TRUE;
   MemorySpaceMap = NULL;
 
   //
@@ -922,7 +921,8 @@ RefreshGcdMemoryAttributes (
                   );
   ASSERT_EFI_ERROR (Status);
 
-  DefaultAttributes = GetMemorySpaceAttributeFromMtrrType (mDefaultMemoryType);
+  DefaultMemoryType = MtrrGetDefaultMemoryType ();
+  DefaultAttributes = GetMemorySpaceAttributeFromMtrrType (DefaultMemoryType);
 
   //
   // Set default attributes to all spaces.
@@ -954,13 +954,15 @@ RefreshGcdMemoryAttributes (
         );
     }
   }
+
   //
-  // Go for variable MTRRs with Non-WB attribute
+  // Go for variable MTRRs with the attribute except for WB and UC attributes
   //
   for (Index = 0; Index < FirmwareVariableMtrrCount; Index++) {
-    if (VariableMtrr[Index].Valid &&
-        VariableMtrr[Index].Type != MTRR_CACHE_WRITE_BACK) {
-      Attributes = GetMemorySpaceAttributeFromMtrrType ((UINT8) VariableMtrr[Index].Type);
+    if (VariableMtrr[Index].Valid &&                          
+        VariableMtrr[Index].Type != MTRR_CACHE_WRITE_BACK &&
+        VariableMtrr[Index].Type != MTRR_CACHE_UNCACHEABLE) {
+      Attributes = GetMemorySpaceAttributeFromMtrrType ((MTRR_MEMORY_CACHE_TYPE) VariableMtrr[Index].Type);
       SetGcdMemorySpaceAttributes (
         MemorySpaceMap,
         NumberOfDescriptors,
@@ -971,6 +973,22 @@ RefreshGcdMemoryAttributes (
     }
   }
 
+  //
+  // Go for variable MTRRs with UC attribute
+  //
+  for (Index = 0; Index < FirmwareVariableMtrrCount; Index++) {
+    if (VariableMtrr[Index].Valid &&
+        VariableMtrr[Index].Type == MTRR_CACHE_UNCACHEABLE) {
+      SetGcdMemorySpaceAttributes (
+        MemorySpaceMap,
+        NumberOfDescriptors,
+        VariableMtrr[Index].BaseAddress,
+        VariableMtrr[Index].Length,
+        EFI_MEMORY_UC
+        );
+    }
+  }
+
   //
   // Go for fixed MTRRs
   //
@@ -984,7 +1002,7 @@ RefreshGcdMemoryAttributes (
     // Check for continuous fixed MTRR sections
     //
     for (SubIndex = 0; SubIndex < 8; SubIndex++) {
-      MtrrType = (UINT8) RShiftU64 (RegValue, SubIndex * 8);
+      MtrrType = (MTRR_MEMORY_CACHE_TYPE) RShiftU64 (RegValue, SubIndex * 8);
       CurrentAttributes = GetMemorySpaceAttributeFromMtrrType (MtrrType);
       if (Length == 0) {
         //
diff --git a/UefiCpuPkg/Include/Library/MtrrLib.h b/UefiCpuPkg/Include/Library/MtrrLib.h
index d24f10f36b..e06fff7f01 100644
--- a/UefiCpuPkg/Include/Library/MtrrLib.h
+++ b/UefiCpuPkg/Include/Library/MtrrLib.h
@@ -1,7 +1,7 @@
 /** @file
   MTRR setting library
 
-  Copyright (c) 2008 - 2010, Intel Corporation. All rights reserved.<BR>
+  Copyright (c) 2008 - 2011, Intel Corporation. All rights reserved.<BR>
   This program and the accompanying materials
   are licensed and made available under the terms and conditions of the BSD License
   which accompanies this distribution.  The full text of the license may be found at
@@ -331,4 +331,16 @@ IsMtrrSupported (
   VOID
   );
 
+/**
+  Returns the default MTRR cache type for the system.
+
+  @return  The default MTRR cache type.
+
+**/
+MTRR_MEMORY_CACHE_TYPE
+EFIAPI
+MtrrGetDefaultMemoryType (
+  VOID
+  );
+
 #endif // _MTRR_LIB_H_
diff --git a/UefiCpuPkg/Library/MtrrLib/MtrrLib.c b/UefiCpuPkg/Library/MtrrLib/MtrrLib.c
index 04c6a1c268..5f1a22c5fd 100644
--- a/UefiCpuPkg/Library/MtrrLib/MtrrLib.c
+++ b/UefiCpuPkg/Library/MtrrLib/MtrrLib.c
@@ -144,17 +144,21 @@ GetFirmwareVariableMtrrCount (
 /**
   Returns the default MTRR cache type for the system.
 
-  @return  MTRR default type
+  @return  The default MTRR cache type.
 
 **/
-UINT64
-GetMtrrDefaultMemoryType (
+MTRR_MEMORY_CACHE_TYPE
+EFIAPI
+MtrrGetDefaultMemoryType (
   VOID
-)
+  )
 {
-  return (AsmReadMsr64 (MTRR_LIB_IA32_MTRR_DEF_TYPE) & 0xff);
-}
+  if (!IsMtrrSupported ()) {
+    return CacheUncacheable;
+  }
 
+  return (MTRR_MEMORY_CACHE_TYPE) (AsmReadMsr64 (MTRR_LIB_IA32_MTRR_DEF_TYPE) & 0x7);
+}
 
 /**
   Preparation before programming MTRR.
@@ -1036,7 +1040,7 @@ MtrrSetMemoryAttribute (
   // The memory type is the same with the type specified by
   // MTRR_LIB_IA32_MTRR_DEF_TYPE.
   //
-  if ((!OverwriteExistingMtrr) && (Attribute == GetMtrrDefaultMemoryType ())) {
+  if ((!OverwriteExistingMtrr) && (Attribute == MtrrGetDefaultMemoryType ())) {
     //
     // Invalidate the now-unused MTRRs
     //