path: root/SecurityPkg/Tcg/Tcg2Smm/Tcg2Smm.c

/** @file
  It updates TPM2 items in ACPI table and registers SMI2 callback
  functions for Tcg2 physical presence, ClearMemory, and sample
  for dTPM StartMethod.

  Caution: This module requires additional review when modified.
  This driver will have external input - variable and ACPINvs data in SMM mode.
  This external input must be validated carefully to avoid security issue.

  PhysicalPresenceCallback() and MemoryClearCallback() will receive untrusted input and do some check.

Copyright (c) 2015 - 2016, 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 
http://opensource.org/licenses/bsd-license.php

THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, 
WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.

**/

#include "Tcg2Smm.h"

typedef enum {
  PtpInterfaceTis,
  PtpInterfaceFifo,
  PtpInterfaceCrb,
  PtpInterfaceMax,
} PTP_INTERFACE_TYPE;

/**
  Return PTP interface type.

  @param[in] Register                Pointer to PTP register.

  @return PTP interface type.
**/
PTP_INTERFACE_TYPE
GetPtpInterface (
  IN VOID *Register
  )
{
  PTP_CRB_INTERFACE_IDENTIFIER  InterfaceId;
  PTP_FIFO_INTERFACE_CAPABILITY InterfaceCapability;

  //
  // Check interface id
  //
  InterfaceId.Uint32 = MmioRead32 ((UINTN)&((PTP_CRB_REGISTERS *)Register)->InterfaceId);
  InterfaceCapability.Uint32 = MmioRead32 ((UINTN)&((PTP_FIFO_REGISTERS *)Register)->InterfaceCapability);

  if (InterfaceId.Bits.InterfaceType == PTP_INTERFACE_IDENTIFIER_INTERFACE_TYPE_TIS) {
    return PtpInterfaceTis;
  }

  if ((InterfaceId.Bits.InterfaceType == PTP_INTERFACE_IDENTIFIER_INTERFACE_TYPE_CRB) &&
      (InterfaceId.Bits.InterfaceVersion == PTP_INTERFACE_IDENTIFIER_INTERFACE_VERSION_CRB) &&
      (InterfaceId.Bits.CapCRB != 0)) {
    return PtpInterfaceCrb;
  }

  if ((InterfaceId.Bits.InterfaceType == PTP_INTERFACE_IDENTIFIER_INTERFACE_TYPE_FIFO) &&
      (InterfaceId.Bits.InterfaceVersion == PTP_INTERFACE_IDENTIFIER_INTERFACE_VERSION_FIFO) &&
      (InterfaceId.Bits.CapFIFO != 0) &&
      (InterfaceCapability.Bits.InterfaceVersion == INTERFACE_CAPABILITY_INTERFACE_VERSION_PTP)) {
    return PtpInterfaceFifo;
  }

  //
  // No Ptp interface available
  //
  return PtpInterfaceMax;
}

EFI_TPM2_ACPI_TABLE  mTpm2AcpiTemplate = {
  {
    EFI_ACPI_5_0_TRUSTED_COMPUTING_PLATFORM_2_TABLE_SIGNATURE,
    sizeof (mTpm2AcpiTemplate),
    EFI_TPM2_ACPI_TABLE_REVISION,
    //
    // Compiler initializes the remaining bytes to 0
    // These fields should be filled in in production
    //
  },
  0, // Flags
  0, // Control Area
  EFI_TPM2_ACPI_TABLE_START_METHOD_TIS, // StartMethod
};

EFI_SMM_VARIABLE_PROTOCOL  *mSmmVariable;
TCG_NVS                    *mTcgNvs;

/**
  Software SMI callback for TPM physical presence which is called from ACPI method.

  Caution: This function may receive untrusted input.
  Variable and ACPINvs are external input, so this function will validate
  its data structure to be valid value.

  @param[in]      DispatchHandle  The unique handle assigned to this handler by SmiHandlerRegister().
  @param[in]      Context         Points to an optional handler context which was specified when the
                                  handler was registered.
  @param[in, out] CommBuffer      A pointer to a collection of data in memory that will
                                  be conveyed from a non-SMM environment into an SMM environment.
  @param[in, out] CommBufferSize  The size of the CommBuffer.

  @retval EFI_SUCCESS             The interrupt was handled successfully.

**/
EFI_STATUS
EFIAPI
PhysicalPresenceCallback (
  IN EFI_HANDLE                  DispatchHandle,
  IN CONST VOID                  *Context,
  IN OUT VOID                    *CommBuffer,
  IN OUT UINTN                   *CommBufferSize
  )
{
  UINT32                MostRecentRequest;
  UINT32                Response;
  UINT32                OperationRequest;
  UINT32                RequestParameter;


  if (mTcgNvs->PhysicalPresence.Parameter == TCG_ACPI_FUNCTION_RETURN_REQUEST_RESPONSE_TO_OS) {
    mTcgNvs->PhysicalPresence.ReturnCode = Tcg2PhysicalPresenceLibReturnOperationResponseToOsFunction (
                                             &MostRecentRequest,
                                             &Response
                                             );
    mTcgNvs->PhysicalPresence.LastRequest = MostRecentRequest;
    mTcgNvs->PhysicalPresence.Response = Response;
    return EFI_SUCCESS;
  } else if ((mTcgNvs->PhysicalPresence.Parameter == TCG_ACPI_FUNCTION_SUBMIT_REQUEST_TO_BIOS) 
          || (mTcgNvs->PhysicalPresence.Parameter == TCG_ACPI_FUNCTION_SUBMIT_REQUEST_TO_BIOS_2)) {

    OperationRequest = mTcgNvs->PhysicalPresence.Request;
    RequestParameter = mTcgNvs->PhysicalPresence.RequestParameter;
    mTcgNvs->PhysicalPresence.ReturnCode = Tcg2PhysicalPresenceLibSubmitRequestToPreOSFunctionEx (
                                             &OperationRequest,
                                             &RequestParameter
                                             );
    mTcgNvs->PhysicalPresence.Request = OperationRequest;
    mTcgNvs->PhysicalPresence.RequestParameter = RequestParameter;
  } else if (mTcgNvs->PhysicalPresence.Parameter == TCG_ACPI_FUNCTION_GET_USER_CONFIRMATION_STATUS_FOR_REQUEST) {
    mTcgNvs->PhysicalPresence.ReturnCode = Tcg2PhysicalPresenceLibGetUserConfirmationStatusFunction (mTcgNvs->PPRequestUserConfirm);
  }

  return EFI_SUCCESS;
}


/**
  Software SMI callback for MemoryClear which is called from ACPI method.

  Caution: This function may receive untrusted input.
  Variable and ACPINvs are external input, so this function will validate
  its data structure to be valid value.

  @param[in]      DispatchHandle  The unique handle assigned to this handler by SmiHandlerRegister().
  @param[in]      Context         Points to an optional handler context which was specified when the
                                  handler was registered.
  @param[in, out] CommBuffer      A pointer to a collection of data in memory that will
                                  be conveyed from a non-SMM environment into an SMM environment.
  @param[in, out] CommBufferSize  The size of the CommBuffer.

  @retval EFI_SUCCESS             The interrupt was handled successfully.

**/
EFI_STATUS
EFIAPI
MemoryClearCallback (
  IN EFI_HANDLE                  DispatchHandle,
  IN CONST VOID                  *Context,
  IN OUT VOID                    *CommBuffer,
  IN OUT UINTN                   *CommBufferSize
  )
{
  EFI_STATUS                     Status;
  UINTN                          DataSize;
  UINT8                          MorControl;

  mTcgNvs->MemoryClear.ReturnCode = MOR_REQUEST_SUCCESS;
  if (mTcgNvs->MemoryClear.Parameter == ACPI_FUNCTION_DSM_MEMORY_CLEAR_INTERFACE) {
    MorControl = (UINT8) mTcgNvs->MemoryClear.Request;
  } else if (mTcgNvs->MemoryClear.Parameter == ACPI_FUNCTION_PTS_CLEAR_MOR_BIT) {
    DataSize = sizeof (UINT8);
    Status = mSmmVariable->SmmGetVariable (
                             MEMORY_OVERWRITE_REQUEST_VARIABLE_NAME,
                             &gEfiMemoryOverwriteControlDataGuid,
                             NULL,
                             &DataSize,
                             &MorControl
                             );
    if (EFI_ERROR (Status)) {
      mTcgNvs->MemoryClear.ReturnCode = MOR_REQUEST_GENERAL_FAILURE;
      DEBUG ((EFI_D_ERROR, "[TPM] Get MOR variable failure! Status = %r\n", Status));
      return EFI_SUCCESS;
    }

    if (MOR_CLEAR_MEMORY_VALUE (MorControl) == 0x0) {
      return EFI_SUCCESS;
    }
    MorControl &= ~MOR_CLEAR_MEMORY_BIT_MASK;
  }

  DataSize = sizeof (UINT8);
  Status = mSmmVariable->SmmSetVariable (
                           MEMORY_OVERWRITE_REQUEST_VARIABLE_NAME,
                           &gEfiMemoryOverwriteControlDataGuid,
                           EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,
                           DataSize,
                           &MorControl
                           );
  if (EFI_ERROR (Status)) { 
    mTcgNvs->MemoryClear.ReturnCode = MOR_REQUEST_GENERAL_FAILURE;
    DEBUG ((EFI_D_ERROR, "[TPM] Set MOR variable failure! Status = %r\n", Status));
  }

  return EFI_SUCCESS;
}

/**
  Find the operation region in TCG ACPI table by given Name and Size,
  and initialize it if the region is found.

  @param[in, out] Table          The TPM item in ACPI table.
  @param[in]      Name           The name string to find in TPM table.
  @param[in]      Size           The size of the region to find.

  @return                        The allocated address for the found region.

**/
VOID *
AssignOpRegion (
  EFI_ACPI_DESCRIPTION_HEADER    *Table,
  UINT32                         Name,
  UINT16                         Size
  )
{
  EFI_STATUS                     Status;
  AML_OP_REGION_32_8             *OpRegion;
  EFI_PHYSICAL_ADDRESS           MemoryAddress;

  MemoryAddress = SIZE_4GB - 1;

  //
  // Patch some pointers for the ASL code before loading the SSDT.
  //
  for (OpRegion  = (AML_OP_REGION_32_8 *) (Table + 1);
       OpRegion <= (AML_OP_REGION_32_8 *) ((UINT8 *) Table + Table->Length);
       OpRegion  = (AML_OP_REGION_32_8 *) ((UINT8 *) OpRegion + 1)) {
    if ((OpRegion->OpRegionOp  == AML_EXT_REGION_OP) && 
        (OpRegion->NameString  == Name) &&
        (OpRegion->DWordPrefix == AML_DWORD_PREFIX) &&
        (OpRegion->BytePrefix  == AML_BYTE_PREFIX)) {

      Status = gBS->AllocatePages(AllocateMaxAddress, EfiACPIMemoryNVS, EFI_SIZE_TO_PAGES (Size), &MemoryAddress);
      ASSERT_EFI_ERROR (Status);
      ZeroMem ((VOID *)(UINTN)MemoryAddress, Size);
      OpRegion->RegionOffset = (UINT32) (UINTN) MemoryAddress;
      OpRegion->RegionLen    = (UINT8) Size;
      break;
    }
  }

  return (VOID *) (UINTN) MemoryAddress;
}

/**
  Patch version string of Physical Presence interface supported by platform. The initial string tag in TPM 
ACPI table is "$PV".

  @param[in, out] Table          The TPM item in ACPI table.
  @param[in]      PPVer          Version string of Physical Presence interface supported by platform.

  @return                        The allocated address for the found region.

**/
EFI_STATUS
UpdatePPVersion (
  EFI_ACPI_DESCRIPTION_HEADER    *Table,
  CHAR8                          *PPVer
  )
{
  EFI_STATUS  Status;
  UINT8       *DataPtr;

  //
  // Patch some pointers for the ASL code before loading the SSDT.
  //
  for (DataPtr  = (UINT8 *)(Table + 1);
       DataPtr <= (UINT8 *) ((UINT8 *) Table + Table->Length - PHYSICAL_PRESENCE_VERSION_SIZE);
       DataPtr += 1) {
    if (AsciiStrCmp((CHAR8 *)DataPtr,  PHYSICAL_PRESENCE_VERSION_TAG) == 0) {
      Status = AsciiStrCpyS((CHAR8 *)DataPtr, PHYSICAL_PRESENCE_VERSION_SIZE, PPVer);
      DEBUG((EFI_D_INFO, "TPM2 Physical Presence Interface Version update status 0x%x\n", Status));
      return Status;
    }
  }

  return EFI_NOT_FOUND;
}

/**
  Patch TPM2 device HID string.  The initial string tag in TPM2 ACPI table is "NNN0000".

  @param[in, out] Table          The TPM2 SSDT ACPI table.

  @return                               HID Update status.

**/
EFI_STATUS
UpdateHID (
  EFI_ACPI_DESCRIPTION_HEADER    *Table
  )
{
  EFI_STATUS  Status;
  UINT8       *DataPtr;
  CHAR8       HID[TPM_HID_ACPI_SIZE];
  UINT32      ManufacturerID;
  UINT32      FirmwareVersion1;
  UINT32      FirmwareVersion2;
  BOOLEAN     PnpHID;

  PnpHID = TRUE;

  //
  // Initialize HID with Default PNP string
  //
  ZeroMem(HID, TPM_HID_ACPI_SIZE);
  CopyMem(HID, TPM_HID_TAG, TPM_HID_PNP_SIZE);

  //
  // Get Manufacturer ID
  //
  Status = Tpm2GetCapabilityManufactureID(&ManufacturerID);
  if (!EFI_ERROR(Status)) {
    DEBUG((EFI_D_INFO, "TPM_PT_MANUFACTURER 0x%08x\n", ManufacturerID));
    //
    // ManfacturerID defined in TCG Vendor ID Registry 
    // may tailed with 0x00 or 0x20
    //
    if ((ManufacturerID >> 24) == 0x00 || ((ManufacturerID >> 24) == 0x20)) {
      //
      //  HID containing PNP ID "NNN####"
      //   NNN is uppercase letter for Vendor ID specified by manufacturer
      //
      CopyMem(HID, &ManufacturerID, 3);
    } else {
      //
      //  HID containing ACP ID "NNNN####"
      //   NNNN is uppercase letter for Vendor ID specified by manufacturer
      //
      CopyMem(HID, &ManufacturerID, 4);
      PnpHID = FALSE;
    }
  } else {
    DEBUG ((EFI_D_ERROR, "Get TPM_PT_MANUFACTURER failed %x!\n", Status));
    ASSERT(FALSE);
    return Status;
  }

  Status = Tpm2GetCapabilityFirmwareVersion(&FirmwareVersion1, &FirmwareVersion2);
  if (!EFI_ERROR(Status)) {
    DEBUG((EFI_D_INFO, "TPM_PT_FIRMWARE_VERSION_1 0x%x\n", FirmwareVersion1));
    DEBUG((EFI_D_INFO, "TPM_PT_FIRMWARE_VERSION_2 0x%x\n", FirmwareVersion2));
    //
    //   #### is Firmware Version 1
    //
    if (PnpHID) {
      AsciiSPrint(HID + 3, TPM_HID_PNP_SIZE - 3, "%02d%02d", ((FirmwareVersion1 & 0xFFFF0000) >> 16), (FirmwareVersion1 && 0x0000FFFF));
    } else {
      AsciiSPrint(HID + 4, TPM_HID_ACPI_SIZE - 4, "%02d%02d", ((FirmwareVersion1 & 0xFFFF0000) >> 16), (FirmwareVersion1 && 0x0000FFFF));
    }
    
  } else {
    DEBUG ((EFI_D_ERROR, "Get TPM_PT_FIRMWARE_VERSION_X failed %x!\n", Status));
    ASSERT(FALSE);
    return Status;
  }

  //
  // Patch HID in ASL code before loading the SSDT.
  //
  for (DataPtr  = (UINT8 *)(Table + 1);
       DataPtr <= (UINT8 *) ((UINT8 *) Table + Table->Length - TPM_HID_PNP_SIZE);
       DataPtr += 1) {
    if (AsciiStrCmp((CHAR8 *)DataPtr,  TPM_HID_TAG) == 0) {
      if (PnpHID) {
        CopyMem(DataPtr, HID, TPM_HID_PNP_SIZE);
      } else {
        //
        // NOOP will be patched to '\0'
        //
        CopyMem(DataPtr, HID, TPM_HID_ACPI_SIZE);
      }
      DEBUG((EFI_D_INFO, "TPM2 ACPI _HID updated to %a\n", HID));
      return Status;
    }
  }

  DEBUG((EFI_D_ERROR, "TPM2 ACPI HID TAG for patch not found!\n"));
  return EFI_NOT_FOUND;
}

/**
  Initialize and publish TPM items in ACPI table.

  @retval   EFI_SUCCESS     The TCG ACPI table is published successfully.
  @retval   Others          The TCG ACPI table is not published.

**/
EFI_STATUS
PublishAcpiTable (
  VOID
  )
{
  EFI_STATUS                     Status;
  EFI_ACPI_TABLE_PROTOCOL        *AcpiTable;
  UINTN                          TableKey;
  EFI_ACPI_DESCRIPTION_HEADER    *Table;
  UINTN                          TableSize;

  Status = GetSectionFromFv (
             &gEfiCallerIdGuid,
             EFI_SECTION_RAW,
             0,
             (VOID **) &Table,
             &TableSize
             );
  ASSERT_EFI_ERROR (Status);

  //
  // Update Table version before measuring it to PCR
  //
  Status = UpdatePPVersion(Table, (CHAR8 *)PcdGetPtr(PcdTcgPhysicalPresenceInterfaceVer));
  ASSERT_EFI_ERROR (Status);

  //
  // Update TPM2 HID before measuring it to PCR
  //
  Status = UpdateHID(Table);
  if (EFI_ERROR(Status)) {
    return Status;
  }

  //
  // Measure to PCR[0] with event EV_POST_CODE ACPI DATA
  //
  TpmMeasureAndLogData(
    0,
    EV_POST_CODE,
    EV_POSTCODE_INFO_ACPI_DATA,
    ACPI_DATA_LEN,
    Table,
    TableSize
    );


  ASSERT (Table->OemTableId == SIGNATURE_64 ('T', 'p', 'm', '2', 'T', 'a', 'b', 'l'));
  CopyMem (Table->OemId, PcdGetPtr (PcdAcpiDefaultOemId), sizeof (Table->OemId) );
  mTcgNvs = AssignOpRegion (Table, SIGNATURE_32 ('T', 'N', 'V', 'S'), (UINT16) sizeof (TCG_NVS));
  ASSERT (mTcgNvs != NULL);

  //
  // Publish the TPM ACPI table. Table is re-checksumed.
  //
  Status = gBS->LocateProtocol (&gEfiAcpiTableProtocolGuid, NULL, (VOID **) &AcpiTable);
  ASSERT_EFI_ERROR (Status);

  TableKey = 0;
  Status = AcpiTable->InstallAcpiTable (
                        AcpiTable,
                        Table,
                        TableSize,
                        &TableKey
                        );
  ASSERT_EFI_ERROR (Status);

  return Status;
}

/**
  Publish TPM2 ACPI table

  @retval   EFI_SUCCESS     The TPM2 ACPI table is published successfully.
  @retval   Others          The TPM2 ACPI table is not published.

**/
EFI_STATUS
PublishTpm2 (
  VOID
  )
{
  EFI_STATUS                     Status;
  EFI_ACPI_TABLE_PROTOCOL        *AcpiTable;
  UINTN                          TableKey;
  UINT64                         OemTableId;
  EFI_TPM2_ACPI_CONTROL_AREA     *ControlArea;
  PTP_INTERFACE_TYPE             InterfaceType;

  //
  // Measure to PCR[0] with event EV_POST_CODE ACPI DATA
  //
  TpmMeasureAndLogData(
    0,
    EV_POST_CODE,
    EV_POSTCODE_INFO_ACPI_DATA,
    ACPI_DATA_LEN,
    &mTpm2AcpiTemplate,
    sizeof(mTpm2AcpiTemplate)
    );

  InterfaceType = GetPtpInterface ((VOID *) (UINTN) PcdGet64 (PcdTpmBaseAddress));
  switch (InterfaceType) {
  case PtpInterfaceCrb:
    mTpm2AcpiTemplate.StartMethod = EFI_TPM2_ACPI_TABLE_START_METHOD_COMMAND_RESPONSE_BUFFER_INTERFACE;
    mTpm2AcpiTemplate.AddressOfControlArea = PcdGet64 (PcdTpmBaseAddress) + 0x40;
    ControlArea = (EFI_TPM2_ACPI_CONTROL_AREA *)(UINTN)mTpm2AcpiTemplate.AddressOfControlArea;
    ControlArea->CommandSize  = 0xF80;
    ControlArea->ResponseSize = 0xF80;
    ControlArea->Command      = PcdGet64 (PcdTpmBaseAddress) + 0x80;
    ControlArea->Response     = PcdGet64 (PcdTpmBaseAddress) + 0x80;
    break;
  case PtpInterfaceFifo:
  case PtpInterfaceTis:
    break;
  default:
    DEBUG((EFI_D_ERROR, "TPM2 InterfaceType get error! %d\n", InterfaceType));
    break;
  }

  CopyMem (mTpm2AcpiTemplate.Header.OemId, PcdGetPtr (PcdAcpiDefaultOemId), sizeof (mTpm2AcpiTemplate.Header.OemId));
  OemTableId = PcdGet64 (PcdAcpiDefaultOemTableId);
  CopyMem (&mTpm2AcpiTemplate.Header.OemTableId, &OemTableId, sizeof (UINT64));
  mTpm2AcpiTemplate.Header.OemRevision      = PcdGet32 (PcdAcpiDefaultOemRevision);
  mTpm2AcpiTemplate.Header.CreatorId        = PcdGet32 (PcdAcpiDefaultCreatorId);
  mTpm2AcpiTemplate.Header.CreatorRevision  = PcdGet32 (PcdAcpiDefaultCreatorRevision);

  //
  // Construct ACPI table
  //
  Status = gBS->LocateProtocol (&gEfiAcpiTableProtocolGuid, NULL, (VOID **) &AcpiTable);
  ASSERT_EFI_ERROR (Status);

  Status = AcpiTable->InstallAcpiTable (
                        AcpiTable,
                        &mTpm2AcpiTemplate,
                        sizeof(mTpm2AcpiTemplate),
                        &TableKey
                        );
  ASSERT_EFI_ERROR (Status);

  return Status;
}

/**
  The driver's entry point.

  It install callbacks for TPM physical presence and MemoryClear, and locate 
  SMM variable to be used in the callback function.

  @param[in] ImageHandle  The firmware allocated handle for the EFI image.  
  @param[in] SystemTable  A pointer to the EFI System Table.
  
  @retval EFI_SUCCESS     The entry point is executed successfully.
  @retval Others          Some error occurs when executing this entry point.

**/
EFI_STATUS
EFIAPI
InitializeTcgSmm (
  IN EFI_HANDLE                  ImageHandle,
  IN EFI_SYSTEM_TABLE            *SystemTable
  )
{
  EFI_STATUS                     Status;
  EFI_SMM_SW_DISPATCH2_PROTOCOL  *SwDispatch;
  EFI_SMM_SW_REGISTER_CONTEXT    SwContext;
  EFI_HANDLE                     SwHandle;

  if (!CompareGuid (PcdGetPtr(PcdTpmInstanceGuid), &gEfiTpmDeviceInstanceTpm20DtpmGuid)){
    DEBUG ((EFI_D_ERROR, "No TPM2 DTPM instance required!\n"));
    return EFI_UNSUPPORTED;
  }

  Status = PublishAcpiTable ();
  ASSERT_EFI_ERROR (Status);

  //
  // Get the Sw dispatch protocol and register SMI callback functions.
  //
  Status = gSmst->SmmLocateProtocol (&gEfiSmmSwDispatch2ProtocolGuid, NULL, (VOID**)&SwDispatch);
  ASSERT_EFI_ERROR (Status);
  SwContext.SwSmiInputValue = (UINTN) -1;
  Status = SwDispatch->Register (SwDispatch, PhysicalPresenceCallback, &SwContext, &SwHandle);
  ASSERT_EFI_ERROR (Status);
  if (EFI_ERROR (Status)) {
    return Status;
  }
  mTcgNvs->PhysicalPresence.SoftwareSmi = (UINT8) SwContext.SwSmiInputValue;

  SwContext.SwSmiInputValue = (UINTN) -1;
  Status = SwDispatch->Register (SwDispatch, MemoryClearCallback, &SwContext, &SwHandle);
  ASSERT_EFI_ERROR (Status);
  if (EFI_ERROR (Status)) {
    return Status;
  }
  mTcgNvs->MemoryClear.SoftwareSmi = (UINT8) SwContext.SwSmiInputValue;
  
  //
  // Locate SmmVariableProtocol.
  //
  Status = gSmst->SmmLocateProtocol (&gEfiSmmVariableProtocolGuid, NULL, (VOID**)&mSmmVariable);
  ASSERT_EFI_ERROR (Status);

  //
  // Set TPM2 ACPI table
  //
  Status = PublishTpm2 ();
  ASSERT_EFI_ERROR (Status);


  return EFI_SUCCESS;
}