[PATCH v14 2/8] UefiCpuPkg: Adds MmSaveStateLib library class

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

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

Adds MmSaveStateLib Library class in UefiCpuPkg.dec.
Adds function declaration header file.

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>
Reviewed-by: Ray Ni <ray.ni@intel.com>
---
 UefiCpuPkg/UefiCpuPkg.dec                   |  4 ++
 UefiCpuPkg/Include/Library/MmSaveStateLib.h | 74 +++++++++++++++++++++
 2 files changed, 78 insertions(+)
 create mode 100644 UefiCpuPkg/Include/Library/MmSaveStateLib.h

diff --git a/UefiCpuPkg/UefiCpuPkg.dec b/UefiCpuPkg/UefiCpuPkg.dec
index d31c3b127c0b..1f1b10e702bf 100644
--- a/UefiCpuPkg/UefiCpuPkg.dec
+++ b/UefiCpuPkg/UefiCpuPkg.dec
@@ -2,6 +2,7 @@
 # This Package provides UEFI compatible CPU modules and libraries.
 #
 # Copyright (c) 2007 - 2023, Intel Corporation. All rights reserved.<BR>
+# Copyright (C) 2023 Advanced Micro Devices, Inc. All rights reserved.<BR>
 #
 # SPDX-License-Identifier: BSD-2-Clause-Patent
 #
@@ -60,6 +61,9 @@ [LibraryClasses.IA32, LibraryClasses.X64]
   ##  @libraryclass  Provides function for manipulating x86 paging structures.
   CpuPageTableLib|Include/Library/CpuPageTableLib.h
 
+  ## @libraryclass   Provides functions for manipulating smram savestate registers.
+  MmSaveStateLib|Include/Library/MmSaveStateLib.h
+
 [Guids]
   gUefiCpuPkgTokenSpaceGuid      = { 0xac05bf33, 0x995a, 0x4ed4, { 0xaa, 0xb8, 0xef, 0x7a, 0xe8, 0xf, 0x5c, 0xb0 }}
   gMsegSmramGuid                 = { 0x5802bce4, 0xeeee, 0x4e33, { 0xa1, 0x30, 0xeb, 0xad, 0x27, 0xf0, 0xe4, 0x39 }}
diff --git a/UefiCpuPkg/Include/Library/MmSaveStateLib.h b/UefiCpuPkg/Include/Library/MmSaveStateLib.h
new file mode 100644
index 000000000000..db4552e4a809
--- /dev/null
+++ b/UefiCpuPkg/Include/Library/MmSaveStateLib.h
@@ -0,0 +1,74 @@
+/** @file
+Library that provides service to read/write CPU specific smram save state registers.
+
+Copyright (c) 2010 - 2019, Intel Corporation. All rights reserved.<BR>
+Copyright (C) 2023 Advanced Micro Devices, Inc. All rights reserved.<BR>
+
+@note
+  SaveState(Read/Write) of EFI_SMM_SAVE_STATE_REGISTER_PROCESSOR_ID/EFI_MM_SAVE_STATE_REGISTER_PROCESSOR_ID
+  is handled by PiSmmCpuDxeSmm driver.
+
+SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+
+#ifndef MM_SAVE_STATE_LIB_H_
+#define MM_SAVE_STATE_LIB_H_
+
+#include <Protocol/MmCpu.h>
+#include <Uefi/UefiBaseType.h>
+
+/**
+  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
+  );
+
+/**
+  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
+  );
+
+#endif
-- 
2.25.1