[PATCH v13 3/8] UefiCpuPkg: Implements MmSaveStateLib library instance

["Abdul Lateef Attar" <abdattar@amd.com>]

From: Abdul Lateef Attar <AbdulLateef.Attar@amd.com>

BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=4182

Implements MmSaveStateLib Library class for
AMD cpu family.

Cc: Paul Grimes <paul.grimes@amd.com>
Cc: Abner Chang <abner.chang@amd.com>
Cc: Eric Dong <eric.dong@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Rahul Kumar <rahul1.kumar@intel.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>

Signed-off-by: Abdul Lateef Attar <abdattar@amd.com>
Reviewed-by: Abner Chang <abner.chang@amd.com>
---
 UefiCpuPkg/UefiCpuPkg.dsc                     |   3 +
 .../MmSaveStateLib/AmdMmSaveStateLib.inf      |  34 ++
 .../Library/MmSaveStateLib/MmSaveState.h      |  94 ++++++
 .../Library/MmSaveStateLib/AmdMmSaveState.c   | 309 ++++++++++++++++++
 .../MmSaveStateLib/MmSaveStateCommon.c        | 132 ++++++++
 5 files changed, 572 insertions(+)
 create mode 100644 UefiCpuPkg/Library/MmSaveStateLib/AmdMmSaveStateLib.inf
 create mode 100644 UefiCpuPkg/Library/MmSaveStateLib/MmSaveState.h
 create mode 100644 UefiCpuPkg/Library/MmSaveStateLib/AmdMmSaveState.c
 create mode 100644 UefiCpuPkg/Library/MmSaveStateLib/MmSaveStateCommon.c

diff --git a/UefiCpuPkg/UefiCpuPkg.dsc b/UefiCpuPkg/UefiCpuPkg.dsc
index 593c11cc7482..8b0cb02a80e8 100644
--- a/UefiCpuPkg/UefiCpuPkg.dsc
+++ b/UefiCpuPkg/UefiCpuPkg.dsc
@@ -2,6 +2,7 @@
 #  UefiCpuPkg Package
 #
 #  Copyright (c) 2007 - 2022, Intel Corporation. All rights reserved.<BR>
+#  Copyright (C) 2023 Advanced Micro Devices, Inc. All rights reserved.<BR>
 #
 #  SPDX-License-Identifier: BSD-2-Clause-Patent
 #
@@ -99,6 +100,7 @@ [LibraryClasses.common.DXE_SMM_DRIVER]
   MemoryAllocationLib|MdePkg/Library/SmmMemoryAllocationLib/SmmMemoryAllocationLib.inf
   HobLib|MdePkg/Library/DxeHobLib/DxeHobLib.inf
   CpuExceptionHandlerLib|UefiCpuPkg/Library/CpuExceptionHandlerLib/SmmCpuExceptionHandlerLib.inf
+  MmSaveStateLib|UefiCpuPkg/Library/MmSaveStateLib/AmdMmSaveStateLib.inf
 
 [LibraryClasses.common.MM_STANDALONE]
   MmServicesTableLib|MdePkg/Library/StandaloneMmServicesTableLib/StandaloneMmServicesTableLib.inf
@@ -182,6 +184,7 @@ [Components.IA32, Components.X64]
     <LibraryClasses>
       UnitTestResultReportLib|UnitTestFrameworkPkg/Library/UnitTestResultReportLib/UnitTestResultReportLibConOut.inf
   }
+  UefiCpuPkg/Library/MmSaveStateLib/AmdMmSaveStateLib.inf
 
 [Components.X64]
   UefiCpuPkg/Library/CpuExceptionHandlerLib/UnitTest/DxeCpuExceptionHandlerLibUnitTest.inf
diff --git a/UefiCpuPkg/Library/MmSaveStateLib/AmdMmSaveStateLib.inf b/UefiCpuPkg/Library/MmSaveStateLib/AmdMmSaveStateLib.inf
new file mode 100644
index 000000000000..5c0685f283d3
--- /dev/null
+++ b/UefiCpuPkg/Library/MmSaveStateLib/AmdMmSaveStateLib.inf
@@ -0,0 +1,34 @@
+## @file
+# MM Smram save state service lib.
+#
+# This is MM Smram save state service lib that provide service to read and
+# save savestate area registers.
+#
+# Copyright (C) 2023 Advanced Micro Devices, Inc. All rights reserved.<BR>
+#
+# SPDX-License-Identifier: BSD-2-Clause-Patent
+#
+##
+
+[Defines]
+  INF_VERSION                    = 1.29
+  BASE_NAME                      = AmdMmSaveStateLib
+  FILE_GUID                      = FB7D0A60-E8D4-4EFA-90AA-B357BC569879
+  MODULE_TYPE                    = DXE_SMM_DRIVER
+  VERSION_STRING                 = 1.0
+  LIBRARY_CLASS                  = MmSaveStateLib
+
+[Sources]
+  MmSaveState.h
+  MmSaveStateCommon.c
+  AmdMmSaveState.c
+
+[Packages]
+  MdePkg/MdePkg.dec
+  UefiCpuPkg/UefiCpuPkg.dec
+
+[LibraryClasses]
+  BaseLib
+  BaseMemoryLib
+  DebugLib
+  SmmServicesTableLib
diff --git a/UefiCpuPkg/Library/MmSaveStateLib/MmSaveState.h b/UefiCpuPkg/Library/MmSaveStateLib/MmSaveState.h
new file mode 100644
index 000000000000..c3499cbb3b17
--- /dev/null
+++ b/UefiCpuPkg/Library/MmSaveStateLib/MmSaveState.h
@@ -0,0 +1,94 @@
+/** @file
+  SMRAM Save State Map header file.
+
+  Copyright (c) 2010 - 2019, Intel Corporation. All rights reserved.<BR>
+  Copyright (C) 2023 Advanced Micro Devices, Inc. All rights reserved.<BR>
+  SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+
+#ifndef MM_SAVESTATE_H_
+#define MM_SAVESTATE_H_
+
+#include <Uefi/UefiBaseType.h>
+#include <Protocol/MmCpu.h>
+#include <Library/DebugLib.h>
+#include <Library/MmSaveStateLib.h>
+#include <Library/SmmServicesTableLib.h>
+#include <Library/BaseMemoryLib.h>
+
+// Macro used to simplify the lookup table entries of type CPU_MM_SAVE_STATE_REGISTER_RANGE
+#define MM_REGISTER_RANGE(Start, End)  { Start, End, End - Start + 1 }
+
+// Structure used to describe a range of registers
+typedef struct {
+  EFI_MM_SAVE_STATE_REGISTER    Start;
+  EFI_MM_SAVE_STATE_REGISTER    End;
+  UINTN                         Length;
+} CPU_MM_SAVE_STATE_REGISTER_RANGE;
+
+// Structure used to build a lookup table to retrieve the widths and offsets
+// associated with each supported EFI_MM_SAVE_STATE_REGISTER value
+
+typedef struct {
+  UINT8      Width32;
+  UINT8      Width64;
+  UINT16     Offset32;
+  UINT16     Offset64Lo;
+  UINT16     Offset64Hi;
+  BOOLEAN    Writeable;
+} CPU_MM_SAVE_STATE_LOOKUP_ENTRY;
+
+/**
+  Returns LMA value of the Processor.
+
+  @retval     UINT8     returns LMA bit value.
+**/
+UINT8
+MmSaveStateGetRegisterLma (
+  VOID
+  );
+
+/**
+  Read information from the CPU save state.
+
+  @param  Register  Specifies the CPU register to read form the save state.
+  @param  RegOffset Offset for the next register index.
+
+  @retval 0   Register is not valid
+  @retval >0  Index into mCpuWidthOffset[] associated with Register
+
+**/
+UINTN
+MmSaveStateGetRegisterIndex (
+  IN EFI_MM_SAVE_STATE_REGISTER  Register,
+  IN UINTN                       RegOffset
+  );
+
+/**
+  Read a CPU Save State register on the target processor.
+
+  This function abstracts the differences that whether the CPU Save State register is in the
+  IA32 CPU Save State Map or X64 CPU Save State Map.
+
+  This function supports reading a CPU Save State register in SMBase relocation handler.
+
+  @param[in]  CpuIndex       Specifies the zero-based index of the CPU save state.
+  @param[in]  RegisterIndex  Index into mCpuWidthOffset[] look up table.
+  @param[in]  Width          The number of bytes to read from the CPU save state.
+  @param[out] Buffer         Upon return, this holds the CPU register value read from the save state.
+
+  @retval EFI_SUCCESS           The register was read from Save State.
+  @retval EFI_NOT_FOUND         The register is not defined for the Save State of Processor.
+  @retval EFI_INVALID_PARAMTER  This or Buffer is NULL.
+
+**/
+EFI_STATUS
+MmSaveStateReadRegisterByIndex (
+  IN UINTN  CpuIndex,
+  IN UINTN  RegisterIndex,
+  IN UINTN  Width,
+  OUT VOID  *Buffer
+  );
+
+#endif
diff --git a/UefiCpuPkg/Library/MmSaveStateLib/AmdMmSaveState.c b/UefiCpuPkg/Library/MmSaveStateLib/AmdMmSaveState.c
new file mode 100644
index 000000000000..9fed52896f5c
--- /dev/null
+++ b/UefiCpuPkg/Library/MmSaveStateLib/AmdMmSaveState.c
@@ -0,0 +1,309 @@
+/** @file
+Provides services to access SMRAM Save State Map
+
+Copyright (c) 2010 - 2019, Intel Corporation. All rights reserved.<BR>
+Copyright (C) 2023 Advanced Micro Devices, Inc. All rights reserved.<BR>
+SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+
+#include "MmSaveState.h"
+#include <Register/Amd/SmramSaveStateMap.h>
+#include <Library/BaseLib.h>
+
+// EFER register LMA bit
+#define LMA                                        BIT10
+#define EFER_ADDRESS                               0xC0000080ul
+#define AMD_MM_SAVE_STATE_REGISTER_SMMREVID_INDEX  1
+#define AMD_MM_SAVE_STATE_REGISTER_MAX_INDEX       2
+
+// Macro used to simplify the lookup table entries of type CPU_MM_SAVE_STATE_LOOKUP_ENTRY
+#define MM_CPU_OFFSET(Field)  OFFSET_OF (AMD_SMRAM_SAVE_STATE_MAP, Field)
+
+// Lookup table used to retrieve the widths and offsets associated with each
+// supported EFI_MM_SAVE_STATE_REGISTER value
+CONST CPU_MM_SAVE_STATE_LOOKUP_ENTRY  mCpuWidthOffset[] = {
+  { 0, 0, 0,                            0,                                    FALSE },                                        //  Reserved
+
+  //
+  // Internally defined CPU Save State Registers. Not defined in PI SMM CPU Protocol.
+  //
+  { 4, 4, MM_CPU_OFFSET (x86.SMMRevId), MM_CPU_OFFSET (x64.SMMRevId),         0, FALSE},                                      // AMD_MM_SAVE_STATE_REGISTER_SMMREVID_INDEX  = 1
+
+  //
+  // CPU Save State registers defined in PI SMM CPU Protocol.
+  //
+  { 4, 8, MM_CPU_OFFSET (x86.GDTBase),  MM_CPU_OFFSET (x64._GDTRBaseLoDword), MM_CPU_OFFSET (x64._GDTRBaseHiDword), FALSE},   //  EFI_MM_SAVE_STATE_REGISTER_GDTBASE  = 4
+  { 0, 8, 0,                            MM_CPU_OFFSET (x64._IDTRBaseLoDword), MM_CPU_OFFSET (x64._IDTRBaseLoDword), FALSE},   //  EFI_MM_SAVE_STATE_REGISTER_IDTBASE  = 5
+  { 0, 8, 0,                            MM_CPU_OFFSET (x64._LDTRBaseLoDword), MM_CPU_OFFSET (x64._LDTRBaseLoDword), FALSE},   //  EFI_MM_SAVE_STATE_REGISTER_LDTBASE  = 6
+  { 0, 2, 0,                            MM_CPU_OFFSET (x64._GDTRLimit),       0, FALSE},                                      //  EFI_MM_SAVE_STATE_REGISTER_GDTLIMIT = 7
+  { 0, 2, 0,                            MM_CPU_OFFSET (x64._IDTRLimit),       0, FALSE},                                      //  EFI_MM_SAVE_STATE_REGISTER_IDTLIMIT = 8
+  { 0, 4, 0,                            MM_CPU_OFFSET (x64._LDTRLimit),       0, FALSE},                                      //  EFI_MM_SAVE_STATE_REGISTER_LDTLIMIT = 9
+  { 0, 0, 0,                            0,                                    0, FALSE},                                      //  EFI_MM_SAVE_STATE_REGISTER_LDTINFO  = 10
+  { 4, 2, MM_CPU_OFFSET (x86._ES),      MM_CPU_OFFSET (x64._ES),              0, FALSE},                                      //  EFI_MM_SAVE_STATE_REGISTER_ES       = 20
+  { 4, 2, MM_CPU_OFFSET (x86._CS),      MM_CPU_OFFSET (x64._CS),              0, FALSE},                                      //  EFI_MM_SAVE_STATE_REGISTER_CS       = 21
+  { 4, 2, MM_CPU_OFFSET (x86._SS),      MM_CPU_OFFSET (x64._SS),              0, FALSE},                                      //  EFI_MM_SAVE_STATE_REGISTER_SS       = 22
+  { 4, 2, MM_CPU_OFFSET (x86._DS),      MM_CPU_OFFSET (x64._DS),              0, FALSE},                                      //  EFI_MM_SAVE_STATE_REGISTER_DS       = 23
+  { 4, 2, MM_CPU_OFFSET (x86._FS),      MM_CPU_OFFSET (x64._FS),              0, FALSE},                                      //  EFI_MM_SAVE_STATE_REGISTER_FS       = 24
+  { 4, 2, MM_CPU_OFFSET (x86._GS),      MM_CPU_OFFSET (x64._GS),              0, FALSE},                                      //  EFI_MM_SAVE_STATE_REGISTER_GS       = 25
+  { 0, 2, 0,                            MM_CPU_OFFSET (x64._LDTR),            0, FALSE},                                      //  EFI_MM_SAVE_STATE_REGISTER_LDTR_SEL = 26
+  { 0, 2, 0,                            MM_CPU_OFFSET (x64._TR),              0, FALSE},                                      //  EFI_MM_SAVE_STATE_REGISTER_TR_SEL   = 27
+  { 4, 8, MM_CPU_OFFSET (x86._DR7),     MM_CPU_OFFSET (x64._DR7),             MM_CPU_OFFSET (x64._DR7)         + 4, FALSE},   //  EFI_MM_SAVE_STATE_REGISTER_DR7      = 28
+  { 4, 8, MM_CPU_OFFSET (x86._DR6),     MM_CPU_OFFSET (x64._DR6),             MM_CPU_OFFSET (x64._DR6)         + 4, FALSE},   //  EFI_MM_SAVE_STATE_REGISTER_DR6      = 29
+  { 0, 8, 0,                            MM_CPU_OFFSET (x64._R8),              MM_CPU_OFFSET (x64._R8)          + 4, TRUE},    //  EFI_MM_SAVE_STATE_REGISTER_R8       = 30
+  { 0, 8, 0,                            MM_CPU_OFFSET (x64._R9),              MM_CPU_OFFSET (x64._R9)          + 4, TRUE},    //  EFI_MM_SAVE_STATE_REGISTER_R9       = 31
+  { 0, 8, 0,                            MM_CPU_OFFSET (x64._R10),             MM_CPU_OFFSET (x64._R10)         + 4, TRUE},    //  EFI_MM_SAVE_STATE_REGISTER_R10      = 32
+  { 0, 8, 0,                            MM_CPU_OFFSET (x64._R11),             MM_CPU_OFFSET (x64._R11)         + 4, TRUE},    //  EFI_MM_SAVE_STATE_REGISTER_R11      = 33
+  { 0, 8, 0,                            MM_CPU_OFFSET (x64._R12),             MM_CPU_OFFSET (x64._R12)         + 4, TRUE},    //  EFI_MM_SAVE_STATE_REGISTER_R12      = 34
+  { 0, 8, 0,                            MM_CPU_OFFSET (x64._R13),             MM_CPU_OFFSET (x64._R13)         + 4, TRUE},    //  EFI_MM_SAVE_STATE_REGISTER_R13      = 35
+  { 0, 8, 0,                            MM_CPU_OFFSET (x64._R14),             MM_CPU_OFFSET (x64._R14)         + 4, TRUE},    //  EFI_MM_SAVE_STATE_REGISTER_R14      = 36
+  { 0, 8, 0,                            MM_CPU_OFFSET (x64._R15),             MM_CPU_OFFSET (x64._R15)         + 4, TRUE},    //  EFI_MM_SAVE_STATE_REGISTER_R15      = 37
+  { 4, 8, MM_CPU_OFFSET (x86._EAX),     MM_CPU_OFFSET (x64._RAX),             MM_CPU_OFFSET (x64._RAX)         + 4, TRUE},    //  EFI_MM_SAVE_STATE_REGISTER_RAX      = 38
+  { 4, 8, MM_CPU_OFFSET (x86._EBX),     MM_CPU_OFFSET (x64._RBX),             MM_CPU_OFFSET (x64._RBX)         + 4, TRUE},    //  EFI_MM_SAVE_STATE_REGISTER_RBX      = 39
+  { 4, 8, MM_CPU_OFFSET (x86._ECX),     MM_CPU_OFFSET (x64._RCX),             MM_CPU_OFFSET (x64._RCX)         + 4, TRUE},    //  EFI_MM_SAVE_STATE_REGISTER_RBX      = 39
+  { 4, 8, MM_CPU_OFFSET (x86._EDX),     MM_CPU_OFFSET (x64._RDX),             MM_CPU_OFFSET (x64._RDX)         + 4, TRUE},    //  EFI_MM_SAVE_STATE_REGISTER_RDX      = 41
+  { 4, 8, MM_CPU_OFFSET (x86._ESP),     MM_CPU_OFFSET (x64._RSP),             MM_CPU_OFFSET (x64._RSP)         + 4, TRUE},    //  EFI_MM_SAVE_STATE_REGISTER_RSP      = 42
+  { 4, 8, MM_CPU_OFFSET (x86._EBP),     MM_CPU_OFFSET (x64._RBP),             MM_CPU_OFFSET (x64._RBP)         + 4, TRUE},    //  EFI_MM_SAVE_STATE_REGISTER_RBP      = 43
+  { 4, 8, MM_CPU_OFFSET (x86._ESI),     MM_CPU_OFFSET (x64._RSI),             MM_CPU_OFFSET (x64._RSI)         + 4, TRUE},    //  EFI_MM_SAVE_STATE_REGISTER_RSI      = 44
+  { 4, 8, MM_CPU_OFFSET (x86._EDI),     MM_CPU_OFFSET (x64._RDI),             MM_CPU_OFFSET (x64._RDI)         + 4, TRUE},    //  EFI_MM_SAVE_STATE_REGISTER_RDI      = 45
+  { 4, 8, MM_CPU_OFFSET (x86._EIP),     MM_CPU_OFFSET (x64._RIP),             MM_CPU_OFFSET (x64._RIP)         + 4, TRUE},    //  EFI_MM_SAVE_STATE_REGISTER_RIP      = 46
+
+  { 4, 8, MM_CPU_OFFSET (x86._EFLAGS),  MM_CPU_OFFSET (x64._RFLAGS),          MM_CPU_OFFSET (x64._RFLAGS)      + 4, TRUE},    //  EFI_MM_SAVE_STATE_REGISTER_RFLAGS   = 51
+  { 4, 8, MM_CPU_OFFSET (x86._CR0),     MM_CPU_OFFSET (x64._CR0),             MM_CPU_OFFSET (x64._CR0)         + 4, FALSE},   //  EFI_MM_SAVE_STATE_REGISTER_CR0      = 52
+  { 4, 8, MM_CPU_OFFSET (x86._CR3),     MM_CPU_OFFSET (x64._CR3),             MM_CPU_OFFSET (x64._CR3)         + 4, FALSE},   //  EFI_MM_SAVE_STATE_REGISTER_CR3      = 53
+  { 0, 8, 0,                            MM_CPU_OFFSET (x64._CR4),             MM_CPU_OFFSET (x64._CR4)         + 4, FALSE},   //  EFI_MM_SAVE_STATE_REGISTER_CR4      = 54
+  { 0, 0, 0,                            0,                                    0     }
+};
+
+/**
+  Read a save state register on the target processor.  If this function
+  returns EFI_UNSUPPORTED, then the caller is responsible for reading the
+  MM Save State register.
+
+  @param[in]  CpuIndex  The index of the CPU to read the Save State register.
+                        The value must be between 0 and the NumberOfCpus field in
+                        the System Management System Table (SMST).
+  @param[in]  Register  The MM Save State register to read.
+  @param[in]  Width     The number of bytes to read from the CPU save state.
+  @param[out] Buffer    Upon return, this holds the CPU register value read
+                        from the save state.
+
+  @retval EFI_SUCCESS           The register was read from Save State.
+  @retval EFI_INVALID_PARAMTER  Buffer is NULL.
+  @retval EFI_UNSUPPORTED       This function does not support reading Register.
+  @retval EFI_NOT_FOUND         If desired Register not found.
+**/
+EFI_STATUS
+EFIAPI
+MmSaveStateReadRegister (
+  IN  UINTN                       CpuIndex,
+  IN  EFI_MM_SAVE_STATE_REGISTER  Register,
+  IN  UINTN                       Width,
+  OUT VOID                        *Buffer
+  )
+{
+  UINT32                     SmmRevId;
+  EFI_MM_SAVE_STATE_IO_INFO  *IoInfo;
+  AMD_SMRAM_SAVE_STATE_MAP   *CpuSaveState;
+  UINT8                      DataWidth;
+
+  // Read CPU State
+  CpuSaveState = (AMD_SMRAM_SAVE_STATE_MAP *)gSmst->CpuSaveState[CpuIndex];
+
+  // Check for special EFI_MM_SAVE_STATE_REGISTER_LMA
+  if (Register == EFI_MM_SAVE_STATE_REGISTER_LMA) {
+    // Only byte access is supported for this register
+    if (Width != 1) {
+      return EFI_INVALID_PARAMETER;
+    }
+
+    *(UINT8 *)Buffer = MmSaveStateGetRegisterLma ();
+
+    return EFI_SUCCESS;
+  }
+
+  // Check for special EFI_MM_SAVE_STATE_REGISTER_IO
+  if (Register == EFI_MM_SAVE_STATE_REGISTER_IO) {
+    //
+    // Get SMM Revision ID
+    //
+    MmSaveStateReadRegisterByIndex (CpuIndex, AMD_MM_SAVE_STATE_REGISTER_SMMREVID_INDEX, sizeof (SmmRevId), &SmmRevId);
+
+    //
+    // See if the CPU supports the IOMisc register in the save state
+    //
+    if (SmmRevId < AMD_SMM_MIN_REV_ID_X64) {
+      return EFI_NOT_FOUND;
+    }
+
+    // Check if IO Restart Dword [IO Trap] is valid or not using bit 1.
+    if (!(CpuSaveState->x64.IO_DWord & 0x02u)) {
+      return EFI_NOT_FOUND;
+    }
+
+    // Zero the IoInfo structure that will be returned in Buffer
+    IoInfo = (EFI_MM_SAVE_STATE_IO_INFO *)Buffer;
+    ZeroMem (IoInfo, sizeof (EFI_MM_SAVE_STATE_IO_INFO));
+
+    IoInfo->IoPort = (UINT16)(CpuSaveState->x64.IO_DWord >> 16u);
+
+    if (CpuSaveState->x64.IO_DWord & 0x10u) {
+      IoInfo->IoWidth = EFI_MM_SAVE_STATE_IO_WIDTH_UINT8;
+      DataWidth       = 0x01u;
+    } else if (CpuSaveState->x64.IO_DWord & 0x20u) {
+      IoInfo->IoWidth = EFI_MM_SAVE_STATE_IO_WIDTH_UINT16;
+      DataWidth       = 0x02u;
+    } else {
+      IoInfo->IoWidth = EFI_MM_SAVE_STATE_IO_WIDTH_UINT32;
+      DataWidth       = 0x04u;
+    }
+
+    if (CpuSaveState->x64.IO_DWord & 0x01u) {
+      IoInfo->IoType = EFI_MM_SAVE_STATE_IO_TYPE_INPUT;
+    } else {
+      IoInfo->IoType = EFI_MM_SAVE_STATE_IO_TYPE_OUTPUT;
+    }
+
+    if ((IoInfo->IoType == EFI_MM_SAVE_STATE_IO_TYPE_INPUT) || (IoInfo->IoType == EFI_MM_SAVE_STATE_IO_TYPE_OUTPUT)) {
+      MmSaveStateReadRegister (CpuIndex, EFI_MM_SAVE_STATE_REGISTER_RAX, DataWidth, &IoInfo->IoData);
+    }
+
+    return EFI_SUCCESS;
+  }
+
+  // Convert Register to a register lookup table index
+  return MmSaveStateReadRegisterByIndex (CpuIndex, MmSaveStateGetRegisterIndex (Register, AMD_MM_SAVE_STATE_REGISTER_MAX_INDEX), Width, Buffer);
+}
+
+/**
+  Writes a save state register on the target processor.  If this function
+  returns EFI_UNSUPPORTED, then the caller is responsible for writing the
+  MM save state register.
+
+  @param[in] CpuIndex  The index of the CPU to write the MM Save State.  The
+                       value must be between 0 and the NumberOfCpus field in
+                       the System Management System Table (SMST).
+  @param[in] Register  The MM Save State register to write.
+  @param[in] Width     The number of bytes to write to the CPU save state.
+  @param[in] Buffer    Upon entry, this holds the new CPU register value.
+
+  @retval EFI_SUCCESS           The register was written to Save State.
+  @retval EFI_INVALID_PARAMTER  Buffer is NULL.
+  @retval EFI_UNSUPPORTED       This function does not support writing Register.
+  @retval EFI_NOT_FOUND         If desired Register not found.
+**/
+EFI_STATUS
+EFIAPI
+MmSaveStateWriteRegister (
+  IN UINTN                       CpuIndex,
+  IN EFI_MM_SAVE_STATE_REGISTER  Register,
+  IN UINTN                       Width,
+  IN CONST VOID                  *Buffer
+  )
+{
+  UINTN                     RegisterIndex;
+  AMD_SMRAM_SAVE_STATE_MAP  *CpuSaveState;
+
+  //
+  // Writes to EFI_MM_SAVE_STATE_REGISTER_LMA are ignored
+  //
+  if (Register == EFI_MM_SAVE_STATE_REGISTER_LMA) {
+    return EFI_SUCCESS;
+  }
+
+  //
+  // Writes to EFI_MM_SAVE_STATE_REGISTER_IO are not supported
+  //
+  if (Register == EFI_MM_SAVE_STATE_REGISTER_IO) {
+    return EFI_NOT_FOUND;
+  }
+
+  //
+  // Convert Register to a register lookup table index
+  //
+  RegisterIndex = MmSaveStateGetRegisterIndex (Register, AMD_MM_SAVE_STATE_REGISTER_MAX_INDEX);
+  if (RegisterIndex == 0) {
+    return EFI_NOT_FOUND;
+  }
+
+  CpuSaveState = gSmst->CpuSaveState[CpuIndex];
+
+  //
+  // Do not write non-writable SaveState, because it will cause exception.
+  //
+  if (!mCpuWidthOffset[RegisterIndex].Writeable) {
+    return EFI_UNSUPPORTED;
+  }
+
+  //
+  // Check CPU mode
+  //
+  if (MmSaveStateGetRegisterLma () == EFI_MM_SAVE_STATE_REGISTER_LMA_32BIT) {
+    //
+    // If 32-bit mode width is zero, then the specified register can not be accessed
+    //
+    if (mCpuWidthOffset[RegisterIndex].Width32 == 0) {
+      return EFI_NOT_FOUND;
+    }
+
+    //
+    // If Width is bigger than the 32-bit mode width, then the specified register can not be accessed
+    //
+    if (Width > mCpuWidthOffset[RegisterIndex].Width32) {
+      return EFI_INVALID_PARAMETER;
+    }
+
+    //
+    // Write SMM State register
+    //
+    ASSERT (CpuSaveState != NULL);
+    CopyMem ((UINT8 *)CpuSaveState + mCpuWidthOffset[RegisterIndex].Offset32, Buffer, Width);
+  } else {
+    //
+    // If 64-bit mode width is zero, then the specified register can not be accessed
+    //
+    if (mCpuWidthOffset[RegisterIndex].Width64 == 0) {
+      return EFI_NOT_FOUND;
+    }
+
+    //
+    // If Width is bigger than the 64-bit mode width, then the specified register can not be accessed
+    //
+    if (Width > mCpuWidthOffset[RegisterIndex].Width64) {
+      return EFI_INVALID_PARAMETER;
+    }
+
+    //
+    // Write lower 32-bits of SMM State register
+    //
+    CopyMem ((UINT8 *)CpuSaveState + mCpuWidthOffset[RegisterIndex].Offset64Lo, Buffer, MIN (4, Width));
+    if (Width >= 4) {
+      //
+      // Write upper 32-bits of SMM State register
+      //
+      CopyMem ((UINT8 *)CpuSaveState + mCpuWidthOffset[RegisterIndex].Offset64Hi, (UINT8 *)Buffer + 4, Width - 4);
+    }
+  }
+
+  return EFI_SUCCESS;
+}
+
+/**
+  Returns LMA value of the Processor.
+
+  @retval     UINT8     returns LMA bit value.
+**/
+UINT8
+MmSaveStateGetRegisterLma (
+  VOID
+  )
+{
+  UINT32  LMAValue;
+
+  LMAValue = (UINT32)AsmReadMsr64 (EFER_ADDRESS) & LMA;
+  if (LMAValue) {
+    return EFI_MM_SAVE_STATE_REGISTER_LMA_64BIT;
+  }
+
+  return EFI_MM_SAVE_STATE_REGISTER_LMA_32BIT;
+}
diff --git a/UefiCpuPkg/Library/MmSaveStateLib/MmSaveStateCommon.c b/UefiCpuPkg/Library/MmSaveStateLib/MmSaveStateCommon.c
new file mode 100644
index 000000000000..09c6c3f96fed
--- /dev/null
+++ b/UefiCpuPkg/Library/MmSaveStateLib/MmSaveStateCommon.c
@@ -0,0 +1,132 @@
+/** @file
+  Provides common supporting function to access SMRAM Save State Map
+
+  Copyright (c) 2010 - 2019, Intel Corporation. All rights reserved.<BR>
+  Copyright (C) 2023 Advanced Micro Devices, Inc. All rights reserved.<BR>
+
+  SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+
+#include "MmSaveState.h"
+
+// Table used by MmSaveStateGetRegisterIndex() to convert an EFI_MM_SAVE_STATE_REGISTER
+// value to an index into a table of type CPU_MM_SAVE_STATE_LOOKUP_ENTRY
+CONST CPU_MM_SAVE_STATE_REGISTER_RANGE  mCpuRegisterRanges[] = {
+  MM_REGISTER_RANGE (EFI_MM_SAVE_STATE_REGISTER_GDTBASE, EFI_MM_SAVE_STATE_REGISTER_LDTINFO),
+  MM_REGISTER_RANGE (EFI_MM_SAVE_STATE_REGISTER_ES,      EFI_MM_SAVE_STATE_REGISTER_RIP),
+  MM_REGISTER_RANGE (EFI_MM_SAVE_STATE_REGISTER_RFLAGS,  EFI_MM_SAVE_STATE_REGISTER_CR4),
+  { (EFI_MM_SAVE_STATE_REGISTER)0,                       (EFI_MM_SAVE_STATE_REGISTER)0,      0}
+};
+
+extern CONST CPU_MM_SAVE_STATE_LOOKUP_ENTRY  mCpuWidthOffset[];
+
+/**
+  Read information from the CPU save state.
+
+  @param  Register  Specifies the CPU register to read form the save state.
+  @param  RegOffset Offset for the next register index.
+
+  @retval 0   Register is not valid
+  @retval >0  Index into mCpuWidthOffset[] associated with Register
+
+**/
+UINTN
+MmSaveStateGetRegisterIndex (
+  IN EFI_MM_SAVE_STATE_REGISTER  Register,
+  IN UINTN                       RegOffset
+  )
+{
+  UINTN  Index;
+  UINTN  Offset;
+
+  for (Index = 0, Offset = RegOffset; mCpuRegisterRanges[Index].Length != 0; Index++) {
+    if ((Register >= mCpuRegisterRanges[Index].Start) && (Register <= mCpuRegisterRanges[Index].End)) {
+      return Register - mCpuRegisterRanges[Index].Start + Offset;
+    }
+
+    Offset += mCpuRegisterRanges[Index].Length;
+  }
+
+  return 0;
+}
+
+/**
+  Read a CPU Save State register on the target processor.
+
+  This function abstracts the differences that whether the CPU Save State register is in the
+  IA32 CPU Save State Map or X64 CPU Save State Map.
+
+  This function supports reading a CPU Save State register in SMBase relocation handler.
+
+  @param[in]  CpuIndex       Specifies the zero-based index of the CPU save state.
+  @param[in]  RegisterIndex  Index into mCpuWidthOffset[] look up table.
+  @param[in]  Width          The number of bytes to read from the CPU save state.
+  @param[out] Buffer         Upon return, this holds the CPU register value read from the save state.
+
+  @retval EFI_SUCCESS           The register was read from Save State.
+  @retval EFI_NOT_FOUND         The register is not defined for the Save State of Processor.
+  @retval EFI_INVALID_PARAMTER  This or Buffer is NULL.
+
+**/
+EFI_STATUS
+MmSaveStateReadRegisterByIndex (
+  IN UINTN  CpuIndex,
+  IN UINTN  RegisterIndex,
+  IN UINTN  Width,
+  OUT VOID  *Buffer
+  )
+{
+  if (RegisterIndex == 0) {
+    return EFI_NOT_FOUND;
+  }
+
+  if (MmSaveStateGetRegisterLma () == EFI_MM_SAVE_STATE_REGISTER_LMA_32BIT) {
+    //
+    // If 32-bit mode width is zero, then the specified register can not be accessed
+    //
+    if (mCpuWidthOffset[RegisterIndex].Width32 == 0) {
+      return EFI_NOT_FOUND;
+    }
+
+    //
+    // If Width is bigger than the 32-bit mode width, then the specified register can not be accessed
+    //
+    if (Width > mCpuWidthOffset[RegisterIndex].Width32) {
+      return EFI_INVALID_PARAMETER;
+    }
+
+    //
+    // Write return buffer
+    //
+    ASSERT (gSmst->CpuSaveState[CpuIndex] != NULL);
+    CopyMem (Buffer, (UINT8 *)gSmst->CpuSaveState[CpuIndex] + mCpuWidthOffset[RegisterIndex].Offset32, Width);
+  } else {
+    //
+    // If 64-bit mode width is zero, then the specified register can not be accessed
+    //
+    if (mCpuWidthOffset[RegisterIndex].Width64 == 0) {
+      return EFI_NOT_FOUND;
+    }
+
+    //
+    // If Width is bigger than the 64-bit mode width, then the specified register can not be accessed
+    //
+    if (Width > mCpuWidthOffset[RegisterIndex].Width64) {
+      return EFI_INVALID_PARAMETER;
+    }
+
+    //
+    // Write lower 32-bits of return buffer
+    //
+    CopyMem (Buffer, (UINT8 *)gSmst->CpuSaveState[CpuIndex] + mCpuWidthOffset[RegisterIndex].Offset64Lo, MIN (4, Width));
+    if (Width > 4) {
+      //
+      // Write upper 32-bits of return buffer
+      //
+      CopyMem ((UINT8 *)Buffer + 4, (UINT8 *)gSmst->CpuSaveState[CpuIndex] + mCpuWidthOffset[RegisterIndex].Offset64Hi, Width - 4);
+    }
+  }
+
+  return EFI_SUCCESS;
+}
-- 
2.25.1