diff --git a/UefiCpuPkg/Include/AcpiCpuData.h b/UefiCpuPkg/Include/AcpiCpuData.h
index 130eb90895..ec092074ce 100644
--- a/UefiCpuPkg/Include/AcpiCpuData.h
+++ b/UefiCpuPkg/Include/AcpiCpuData.h
@@ -29,11 +29,13 @@ typedef enum {
 // Element of register table entry
 //
 typedef struct {
-  REGISTER_TYPE  RegisterType;
-  UINT32         Index;
-  UINT8          ValidBitStart;
-  UINT8          ValidBitLength;
-  UINT64         Value;
+  REGISTER_TYPE  RegisterType;          // offset 0 - 3
+  UINT32         Index;                 // offset 4 - 7
+  UINT8          ValidBitStart;         // offset 8
+  UINT8          ValidBitLength;        // offset 9
+  UINT16         Reserved;              // offset 10 - 11
+  UINT32         HighIndex;             // offset 12-15, only valid for MemoryMapped
+  UINT64         Value;                 // offset 16-23
 } CPU_REGISTER_TABLE_ENTRY;
 
 //
diff --git a/UefiCpuPkg/Library/RegisterCpuFeaturesLib/CpuFeaturesInitialize.c b/UefiCpuPkg/Library/RegisterCpuFeaturesLib/CpuFeaturesInitialize.c
index d879591ce0..34e6c6bd58 100644
--- a/UefiCpuPkg/Library/RegisterCpuFeaturesLib/CpuFeaturesInitialize.c
+++ b/UefiCpuPkg/Library/RegisterCpuFeaturesLib/CpuFeaturesInitialize.c
@@ -370,9 +370,9 @@ DumpRegisterTableOnProcessor (
     case MemoryMapped:
       DEBUG ((
         DebugPrintErrorLevel,
-        "Processor: %d:  MMIO: %x, Bit Start: %d, Bit Length: %d, Value: %lx\r\n",
+        "Processor: %d:  MMIO: %lx, Bit Start: %d, Bit Length: %d, Value: %lx\r\n",
         ProcessorNumber,
-        RegisterTableEntry->Index,
+        RegisterTableEntry->Index | LShiftU64 (RegisterTableEntry->HighIndex, 32),
         RegisterTableEntry->ValidBitStart,
         RegisterTableEntry->ValidBitLength,
         RegisterTableEntry->Value
@@ -628,7 +628,7 @@ ProgramProcessorRegister (
     case MemoryMapped:
       AcquireSpinLock (&CpuFeaturesData->MemoryMappedLock);
       MmioBitFieldWrite32 (
-        RegisterTableEntry->Index,
+        (UINTN)(RegisterTableEntry->Index | LShiftU64 (RegisterTableEntry->HighIndex, 32)),
         RegisterTableEntry->ValidBitStart,
         RegisterTableEntry->ValidBitStart + RegisterTableEntry->ValidBitLength - 1,
         (UINT32)RegisterTableEntry->Value
diff --git a/UefiCpuPkg/Library/RegisterCpuFeaturesLib/RegisterCpuFeaturesLib.c b/UefiCpuPkg/Library/RegisterCpuFeaturesLib/RegisterCpuFeaturesLib.c
index 32189cbc79..3fec2e6ca3 100644
--- a/UefiCpuPkg/Library/RegisterCpuFeaturesLib/RegisterCpuFeaturesLib.c
+++ b/UefiCpuPkg/Library/RegisterCpuFeaturesLib/RegisterCpuFeaturesLib.c
@@ -551,6 +551,7 @@ CpuRegisterTableWriteWorker (
   RegisterTableEntry = (CPU_REGISTER_TABLE_ENTRY *) (UINTN) RegisterTable->RegisterTableEntry;
   RegisterTableEntry[RegisterTable->TableLength].RegisterType   = RegisterType;
   RegisterTableEntry[RegisterTable->TableLength].Index          = (UINT32) Index;
+  RegisterTableEntry[RegisterTable->TableLength].HighIndex      = (UINT32) RShiftU64 (Index, 32);
   RegisterTableEntry[RegisterTable->TableLength].ValidBitStart  = ValidBitStart;
   RegisterTableEntry[RegisterTable->TableLength].ValidBitLength = ValidBitLength;
   RegisterTableEntry[RegisterTable->TableLength].Value          = Value;
diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/CpuS3.c b/UefiCpuPkg/PiSmmCpuDxeSmm/CpuS3.c
index c3280b8879..9404501498 100644
--- a/UefiCpuPkg/PiSmmCpuDxeSmm/CpuS3.c
+++ b/UefiCpuPkg/PiSmmCpuDxeSmm/CpuS3.c
@@ -315,7 +315,7 @@ SetProcessorRegister (
     case MemoryMapped:
       AcquireSpinLock (mMemoryMappedLock);
       MmioBitFieldWrite32 (
-        RegisterTableEntry->Index,
+        (UINTN)(RegisterTableEntry->Index | LShiftU64 (RegisterTableEntry->HighIndex, 32)),
         RegisterTableEntry->ValidBitStart,
         RegisterTableEntry->ValidBitStart + RegisterTableEntry->ValidBitLength - 1,
         (UINT32)RegisterTableEntry->Value