path: root/MdeModulePkg/Library/SmmLockBoxLib/SmmLockBoxSmmLib.c

/** @file

Copyright (c) 2010 - 2019, Intel Corporation. All rights reserved.<BR>

SPDX-License-Identifier: BSD-2-Clause-Patent

**/

#include <PiSmm.h>
#include <Library/SmmServicesTableLib.h>
#include <Library/BaseLib.h>
#include <Library/BaseMemoryLib.h>
#include <Library/LockBoxLib.h>
#include <Library/DebugLib.h>
#include <Guid/SmmLockBox.h>
#include <Guid/EndOfS3Resume.h>
#include <Protocol/SmmReadyToLock.h>
#include <Protocol/SmmEndOfDxe.h>
#include <Protocol/SmmSxDispatch2.h>

#include "SmmLockBoxLibPrivate.h"

/**
  We need handle this library carefully. Only one library instance will construct the environment.
  Below 2 global variable can only be used in constructor. They should NOT be used in any other library functions.
**/
SMM_LOCK_BOX_CONTEXT mSmmLockBoxContext;
LIST_ENTRY           mLockBoxQueue = INITIALIZE_LIST_HEAD_VARIABLE (mLockBoxQueue);

BOOLEAN              mSmmConfigurationTableInstalled = FALSE;
VOID                 *mSmmLockBoxRegistrationSmmEndOfDxe = NULL;
VOID                 *mSmmLockBoxRegistrationSmmReadyToLock = NULL;
VOID                 *mSmmLockBoxRegistrationEndOfS3Resume = NULL;
BOOLEAN              mSmmLockBoxSmmReadyToLock = FALSE;
BOOLEAN              mSmmLockBoxDuringS3Resume = FALSE;

/**
  This function return SmmLockBox context from SMST.

  @return SmmLockBox context from SMST.
**/
SMM_LOCK_BOX_CONTEXT *
InternalGetSmmLockBoxContext (
  VOID
  )
{
  UINTN   Index;

  //
  // Check if gEfiSmmLockBoxCommunicationGuid is installed by someone
  //
  for (Index = 0; Index < gSmst->NumberOfTableEntries; Index++) {
    if (CompareGuid (&gSmst->SmmConfigurationTable[Index].VendorGuid, &gEfiSmmLockBoxCommunicationGuid)) {
      //
      // Found. That means some other library instance is already run.
      // No need to install again, just return.
      //
      return (SMM_LOCK_BOX_CONTEXT *)gSmst->SmmConfigurationTable[Index].VendorTable;
    }
  }

  //
  // Not found.
  //
  return NULL;
}

/**
  Notification for SMM ReadyToLock protocol.

  @param[in] Protocol   Points to the protocol's unique identifier.
  @param[in] Interface  Points to the interface instance.
  @param[in] Handle     The handle on which the interface was installed.

  @retval EFI_SUCCESS   Notification runs successfully.
**/
EFI_STATUS
EFIAPI
SmmLockBoxSmmReadyToLockNotify (
  IN CONST EFI_GUID  *Protocol,
  IN VOID            *Interface,
  IN EFI_HANDLE      Handle
  )
{
  mSmmLockBoxSmmReadyToLock = TRUE;
  return EFI_SUCCESS;
}

/**
  Main entry point for an SMM handler dispatch or communicate-based callback.

  @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 and quiesced. No other handlers
                                              should still be called.
  @retval EFI_WARN_INTERRUPT_SOURCE_QUIESCED  The interrupt has been quiesced but other handlers should
                                              still be called.
  @retval EFI_WARN_INTERRUPT_SOURCE_PENDING   The interrupt is still pending and other handlers should still
                                              be called.
  @retval EFI_INTERRUPT_PENDING               The interrupt could not be quiesced.
**/
EFI_STATUS
EFIAPI
SmmLockBoxS3EntryCallBack (
  IN           EFI_HANDLE           DispatchHandle,
  IN     CONST VOID                 *Context         OPTIONAL,
  IN OUT       VOID                 *CommBuffer      OPTIONAL,
  IN OUT       UINTN                *CommBufferSize  OPTIONAL
  )
{
  mSmmLockBoxDuringS3Resume = TRUE;
  return EFI_SUCCESS;
}

/**
  Notification for SMM EndOfDxe protocol.

  @param[in] Protocol   Points to the protocol's unique identifier.
  @param[in] Interface  Points to the interface instance.
  @param[in] Handle     The handle on which the interface was installed.

  @retval EFI_SUCCESS   Notification runs successfully.
**/
EFI_STATUS
EFIAPI
SmmLockBoxSmmEndOfDxeNotify (
  IN CONST EFI_GUID  *Protocol,
  IN VOID            *Interface,
  IN EFI_HANDLE      Handle
  )
{
  EFI_STATUS                        Status;
  EFI_SMM_SX_DISPATCH2_PROTOCOL     *SxDispatch;
  EFI_SMM_SX_REGISTER_CONTEXT       EntryRegisterContext;
  EFI_HANDLE                        S3EntryHandle;

  //
  // Locate SmmSxDispatch2 protocol.
  //
  Status = gSmst->SmmLocateProtocol (
                    &gEfiSmmSxDispatch2ProtocolGuid,
                    NULL,
                    (VOID **)&SxDispatch
                    );
  if (!EFI_ERROR (Status) && (SxDispatch != NULL)) {
    //
    // Register a S3 entry callback function to
    // determine if it will be during S3 resume.
    //
    EntryRegisterContext.Type  = SxS3;
    EntryRegisterContext.Phase = SxEntry;
    Status = SxDispatch->Register (
                           SxDispatch,
                           SmmLockBoxS3EntryCallBack,
                           &EntryRegisterContext,
                           &S3EntryHandle
                           );
    ASSERT_EFI_ERROR (Status);
  }

  return EFI_SUCCESS;
}

/**
  Notification for SMM EndOfS3Resume protocol.

  @param[in] Protocol   Points to the protocol's unique identifier.
  @param[in] Interface  Points to the interface instance.
  @param[in] Handle     The handle on which the interface was installed.

  @retval EFI_SUCCESS   Notification runs successfully.
**/
EFI_STATUS
EFIAPI
SmmLockBoxEndOfS3ResumeNotify (
  IN CONST EFI_GUID  *Protocol,
  IN VOID            *Interface,
  IN EFI_HANDLE      Handle
  )
{
  mSmmLockBoxDuringS3Resume = FALSE;
  return EFI_SUCCESS;
}

/**
  Constructor for SmmLockBox library.
  This is used to set SmmLockBox context, which will be used in PEI phase in S3 boot path later.

  @param[in] ImageHandle  Image handle of this driver.
  @param[in] SystemTable  A Pointer to the EFI System Table.

  @retval EFI_SUCEESS
  @return Others          Some error occurs.
**/
EFI_STATUS
EFIAPI
SmmLockBoxSmmConstructor (
  IN EFI_HANDLE        ImageHandle,
  IN EFI_SYSTEM_TABLE  *SystemTable
  )
{
  EFI_STATUS           Status;
  SMM_LOCK_BOX_CONTEXT *SmmLockBoxContext;

  DEBUG ((DEBUG_INFO, "SmmLockBoxSmmLib SmmLockBoxSmmConstructor - Enter\n"));

  //
  // Register SmmReadyToLock notification.
  //
  Status = gSmst->SmmRegisterProtocolNotify (
                    &gEfiSmmReadyToLockProtocolGuid,
                    SmmLockBoxSmmReadyToLockNotify,
                    &mSmmLockBoxRegistrationSmmReadyToLock
                    );
  ASSERT_EFI_ERROR (Status);

  //
  // Register SmmEndOfDxe notification.
  //
  Status = gSmst->SmmRegisterProtocolNotify (
                    &gEfiSmmEndOfDxeProtocolGuid,
                    SmmLockBoxSmmEndOfDxeNotify,
                    &mSmmLockBoxRegistrationSmmEndOfDxe
                    );
  ASSERT_EFI_ERROR (Status);

  //
  // Register EndOfS3Resume notification.
  //
  Status = gSmst->SmmRegisterProtocolNotify (
                    &gEdkiiEndOfS3ResumeGuid,
                    SmmLockBoxEndOfS3ResumeNotify,
                    &mSmmLockBoxRegistrationEndOfS3Resume
                    );
  ASSERT_EFI_ERROR (Status);

  //
  // Check if gEfiSmmLockBoxCommunicationGuid is installed by someone
  //
  SmmLockBoxContext = InternalGetSmmLockBoxContext ();
  if (SmmLockBoxContext != NULL) {
    //
    // Find it. That means some other library instance is already run.
    // No need to install again, just return.
    //
    DEBUG ((DEBUG_INFO, "SmmLockBoxSmmLib SmmLockBoxContext - already installed\n"));
    DEBUG ((DEBUG_INFO, "SmmLockBoxSmmLib SmmLockBoxSmmConstructor - Exit\n"));
    return EFI_SUCCESS;
  }

  //
  // If no one install this, it means this is first instance. Install it.
  //
  if (sizeof(UINTN) == sizeof(UINT64)) {
    mSmmLockBoxContext.Signature = SMM_LOCK_BOX_SIGNATURE_64;
  } else {
    mSmmLockBoxContext.Signature = SMM_LOCK_BOX_SIGNATURE_32;
  }
  mSmmLockBoxContext.LockBoxDataAddress = (EFI_PHYSICAL_ADDRESS)(UINTN)&mLockBoxQueue;

  Status = gSmst->SmmInstallConfigurationTable (
                    gSmst,
                    &gEfiSmmLockBoxCommunicationGuid,
                    &mSmmLockBoxContext,
                    sizeof(mSmmLockBoxContext)
                    );
  ASSERT_EFI_ERROR (Status);
  mSmmConfigurationTableInstalled = TRUE;

  DEBUG ((DEBUG_INFO, "SmmLockBoxSmmLib SmmLockBoxContext - %x\n", (UINTN)&mSmmLockBoxContext));
  DEBUG ((DEBUG_INFO, "SmmLockBoxSmmLib LockBoxDataAddress - %x\n", (UINTN)&mLockBoxQueue));
  DEBUG ((DEBUG_INFO, "SmmLockBoxSmmLib SmmLockBoxSmmConstructor - Exit\n"));

  return Status;
}

/**
  Destructor for SmmLockBox library.
  This is used to uninstall SmmLockBoxCommunication configuration table
  if it has been installed in Constructor.

  @param[in] ImageHandle    Image handle of this driver.
  @param[in] SystemTable    A Pointer to the EFI System Table.

  @retval EFI_SUCEESS       The destructor always returns EFI_SUCCESS.

**/
EFI_STATUS
EFIAPI
SmmLockBoxSmmDestructor (
  IN EFI_HANDLE         ImageHandle,
  IN EFI_SYSTEM_TABLE   *SystemTable
  )
{
  EFI_STATUS            Status;

  DEBUG ((DEBUG_INFO, "SmmLockBoxSmmLib SmmLockBoxSmmDestructor in %a module\n", gEfiCallerBaseName));

  if (mSmmConfigurationTableInstalled) {
    Status = gSmst->SmmInstallConfigurationTable (
                      gSmst,
                      &gEfiSmmLockBoxCommunicationGuid,
                      NULL,
                      0
                      );
    ASSERT_EFI_ERROR (Status);
    DEBUG ((DEBUG_INFO, "SmmLockBoxSmmLib uninstall SmmLockBoxCommunication configuration table\n"));
  }

  if (mSmmLockBoxRegistrationSmmReadyToLock != NULL) {
    //
    // Unregister SmmReadyToLock notification.
    //
    Status = gSmst->SmmRegisterProtocolNotify (
                      &gEfiSmmReadyToLockProtocolGuid,
                      NULL,
                      &mSmmLockBoxRegistrationSmmReadyToLock
                      );
    ASSERT_EFI_ERROR (Status);
  }
  if (mSmmLockBoxRegistrationSmmEndOfDxe != NULL) {
    //
    // Unregister SmmEndOfDxe notification.
    //
    Status = gSmst->SmmRegisterProtocolNotify (
                      &gEfiSmmEndOfDxeProtocolGuid,
                      NULL,
                      &mSmmLockBoxRegistrationSmmEndOfDxe
                      );
    ASSERT_EFI_ERROR (Status);
  }
  if (mSmmLockBoxRegistrationEndOfS3Resume != NULL) {
    //
    // Unregister EndOfS3Resume notification.
    //
    Status = gSmst->SmmRegisterProtocolNotify (
                      &gEdkiiEndOfS3ResumeGuid,
                      NULL,
                      &mSmmLockBoxRegistrationEndOfS3Resume
                      );
    ASSERT_EFI_ERROR (Status);
  }

  return EFI_SUCCESS;
}

/**
  This function return SmmLockBox queue address.

  @return SmmLockBox queue address.
**/
LIST_ENTRY *
InternalGetLockBoxQueue (
  VOID
  )
{
  SMM_LOCK_BOX_CONTEXT        *SmmLockBoxContext;

  SmmLockBoxContext = InternalGetSmmLockBoxContext ();
  ASSERT (SmmLockBoxContext != NULL);
  if (SmmLockBoxContext == NULL) {
    return NULL;
  }
  return (LIST_ENTRY *)(UINTN)SmmLockBoxContext->LockBoxDataAddress;
}

/**
  This function find LockBox by GUID.

  @param Guid The guid to indentify the LockBox

  @return LockBoxData
**/
SMM_LOCK_BOX_DATA *
InternalFindLockBoxByGuid (
  IN EFI_GUID   *Guid
  )
{
  LIST_ENTRY                    *Link;
  SMM_LOCK_BOX_DATA             *LockBox;
  LIST_ENTRY                    *LockBoxQueue;

  LockBoxQueue = InternalGetLockBoxQueue ();
  ASSERT (LockBoxQueue != NULL);

  for (Link = LockBoxQueue->ForwardLink;
       Link != LockBoxQueue;
       Link = Link->ForwardLink) {
    LockBox = BASE_CR (
                Link,
                SMM_LOCK_BOX_DATA,
                Link
                );
    if (CompareGuid (&LockBox->Guid, Guid)) {
      return LockBox;
    }
  }
  return NULL;
}

/**
  This function will save confidential information to lockbox.

  @param Guid       the guid to identify the confidential information
  @param Buffer     the address of the confidential information
  @param Length     the length of the confidential information

  @retval RETURN_SUCCESS            the information is saved successfully.
  @retval RETURN_INVALID_PARAMETER  the Guid is NULL, or Buffer is NULL, or Length is 0
  @retval RETURN_ALREADY_STARTED    the requested GUID already exist.
  @retval RETURN_OUT_OF_RESOURCES   no enough resource to save the information.
  @retval RETURN_ACCESS_DENIED      it is too late to invoke this interface
  @retval RETURN_NOT_STARTED        it is too early to invoke this interface
  @retval RETURN_UNSUPPORTED        the service is not supported by implementaion.
**/
RETURN_STATUS
EFIAPI
SaveLockBox (
  IN  GUID                        *Guid,
  IN  VOID                        *Buffer,
  IN  UINTN                       Length
  )
{
  SMM_LOCK_BOX_DATA           *LockBox;
  EFI_PHYSICAL_ADDRESS        SmramBuffer;
  EFI_STATUS                  Status;
  LIST_ENTRY                  *LockBoxQueue;

  DEBUG ((DEBUG_INFO, "SmmLockBoxSmmLib SaveLockBox - Enter\n"));

  //
  // Basic check
  //
  if ((Guid == NULL) || (Buffer == NULL) || (Length == 0)) {
    DEBUG ((DEBUG_INFO, "SmmLockBoxSmmLib SaveLockBox - Exit (%r)\n", EFI_INVALID_PARAMETER));
    return EFI_INVALID_PARAMETER;
  }

  //
  // Find LockBox
  //
  LockBox = InternalFindLockBoxByGuid (Guid);
  if (LockBox != NULL) {
    DEBUG ((DEBUG_INFO, "SmmLockBoxSmmLib SaveLockBox - Exit (%r)\n", EFI_ALREADY_STARTED));
    return EFI_ALREADY_STARTED;
  }

  //
  // Allocate SMRAM buffer
  //
  Status = gSmst->SmmAllocatePages (
                    AllocateAnyPages,
                    EfiRuntimeServicesData,
                    EFI_SIZE_TO_PAGES (Length),
                    &SmramBuffer
                    );
  ASSERT_EFI_ERROR (Status);
  if (EFI_ERROR (Status)) {
    DEBUG ((DEBUG_INFO, "SmmLockBoxSmmLib SaveLockBox - Exit (%r)\n", EFI_OUT_OF_RESOURCES));
    return EFI_OUT_OF_RESOURCES;
  }

  //
  // Allocate LockBox
  //
  Status = gSmst->SmmAllocatePool (
                    EfiRuntimeServicesData,
                    sizeof(*LockBox),
                    (VOID **)&LockBox
                    );
  ASSERT_EFI_ERROR (Status);
  if (EFI_ERROR (Status)) {
    gSmst->SmmFreePages (SmramBuffer, EFI_SIZE_TO_PAGES (Length));
    DEBUG ((DEBUG_INFO, "SmmLockBoxSmmLib SaveLockBox - Exit (%r)\n", EFI_OUT_OF_RESOURCES));
    return EFI_OUT_OF_RESOURCES;
  }

  //
  // Save data
  //
  CopyMem ((VOID *)(UINTN)SmramBuffer, (VOID *)(UINTN)Buffer, Length);

  //
  // Insert LockBox to queue
  //
  LockBox->Signature   = SMM_LOCK_BOX_DATA_SIGNATURE;
  CopyMem (&LockBox->Guid, Guid, sizeof(EFI_GUID));
  LockBox->Buffer      = (EFI_PHYSICAL_ADDRESS)(UINTN)Buffer;
  LockBox->Length      = (UINT64)Length;
  LockBox->Attributes  = 0;
  LockBox->SmramBuffer = SmramBuffer;

  DEBUG ((
    DEBUG_INFO,
    "LockBoxGuid - %g, SmramBuffer - 0x%lx, Length - 0x%lx\n",
    &LockBox->Guid,
    LockBox->SmramBuffer,
    LockBox->Length
    ));

  LockBoxQueue = InternalGetLockBoxQueue ();
  ASSERT (LockBoxQueue != NULL);
  InsertTailList (LockBoxQueue, &LockBox->Link);

  //
  // Done
  //
  DEBUG ((DEBUG_INFO, "SmmLockBoxSmmLib SaveLockBox - Exit (%r)\n", EFI_SUCCESS));
  return EFI_SUCCESS;
}

/**
  This function will set lockbox attributes.

  @param Guid       the guid to identify the confidential information
  @param Attributes the attributes of the lockbox

  @retval RETURN_SUCCESS            the information is saved successfully.
  @retval RETURN_INVALID_PARAMETER  attributes is invalid.
  @retval RETURN_NOT_FOUND          the requested GUID not found.
  @retval RETURN_ACCESS_DENIED      it is too late to invoke this interface
  @retval RETURN_NOT_STARTED        it is too early to invoke this interface
  @retval RETURN_UNSUPPORTED        the service is not supported by implementaion.
**/
RETURN_STATUS
EFIAPI
SetLockBoxAttributes (
  IN  GUID                        *Guid,
  IN  UINT64                      Attributes
  )
{
  SMM_LOCK_BOX_DATA              *LockBox;

  DEBUG ((DEBUG_INFO, "SmmLockBoxSmmLib SetLockBoxAttributes - Enter\n"));

  //
  // Basic check
  //
  if ((Guid == NULL) ||
      ((Attributes & ~(LOCK_BOX_ATTRIBUTE_RESTORE_IN_PLACE | LOCK_BOX_ATTRIBUTE_RESTORE_IN_S3_ONLY)) != 0)) {
    DEBUG ((DEBUG_INFO, "SmmLockBoxSmmLib SetLockBoxAttributes - Exit (%r)\n", EFI_INVALID_PARAMETER));
    return EFI_INVALID_PARAMETER;
  }

  if (((Attributes & LOCK_BOX_ATTRIBUTE_RESTORE_IN_PLACE) != 0) &&
      ((Attributes & LOCK_BOX_ATTRIBUTE_RESTORE_IN_S3_ONLY) != 0)) {
    DEBUG ((DEBUG_INFO, "SmmLockBoxSmmLib SetLockBoxAttributes - Exit (%r)\n", EFI_INVALID_PARAMETER));
    DEBUG ((DEBUG_INFO, "  LOCK_BOX_ATTRIBUTE_RESTORE_IN_PLACE and LOCK_BOX_ATTRIBUTE_RESTORE_IN_S3_ONLY\n\n"));
    DEBUG ((DEBUG_INFO, "  can not be set together\n"));
    return EFI_INVALID_PARAMETER;
  }

  //
  // Find LockBox
  //
  LockBox = InternalFindLockBoxByGuid (Guid);
  if (LockBox == NULL) {
    DEBUG ((DEBUG_INFO, "SmmLockBoxSmmLib SetLockBoxAttributes - Exit (%r)\n", EFI_NOT_FOUND));
    return EFI_NOT_FOUND;
  }

  if ((((Attributes & LOCK_BOX_ATTRIBUTE_RESTORE_IN_PLACE) != 0) &&
      ((LockBox->Attributes & LOCK_BOX_ATTRIBUTE_RESTORE_IN_S3_ONLY) != 0)) ||
      (((LockBox->Attributes & LOCK_BOX_ATTRIBUTE_RESTORE_IN_PLACE) != 0) &&
      ((Attributes & LOCK_BOX_ATTRIBUTE_RESTORE_IN_S3_ONLY) != 0))) {
    DEBUG ((DEBUG_INFO, "SmmLockBoxSmmLib SetLockBoxAttributes 0x%lx 0x%lx - Exit (%r)\n", LockBox->Attributes, Attributes, EFI_INVALID_PARAMETER));
    DEBUG ((DEBUG_INFO, "  LOCK_BOX_ATTRIBUTE_RESTORE_IN_PLACE and LOCK_BOX_ATTRIBUTE_RESTORE_IN_S3_ONLY\n\n"));
    DEBUG ((DEBUG_INFO, "  can not be set together\n"));
    return EFI_INVALID_PARAMETER;
  }

  //
  // Update data
  //
  LockBox->Attributes = Attributes;

  //
  // Done
  //
  DEBUG ((DEBUG_INFO, "SmmLockBoxSmmLib SetLockBoxAttributes - Exit (%r)\n", EFI_SUCCESS));
  return EFI_SUCCESS;
}

/**
  This function will update confidential information to lockbox.

  @param Guid   the guid to identify the original confidential information
  @param Offset the offset of the original confidential information
  @param Buffer the address of the updated confidential information
  @param Length the length of the updated confidential information

  @retval RETURN_SUCCESS            the information is saved successfully.
  @retval RETURN_INVALID_PARAMETER  the Guid is NULL, or Buffer is NULL, or Length is 0.
  @retval RETURN_NOT_FOUND          the requested GUID not found.
  @retval RETURN_BUFFER_TOO_SMALL   for lockbox without attribute LOCK_BOX_ATTRIBUTE_RESTORE_IN_S3_ONLY,
                                    the original buffer to too small to hold new information.
  @retval RETURN_OUT_OF_RESOURCES   for lockbox with attribute LOCK_BOX_ATTRIBUTE_RESTORE_IN_S3_ONLY,
                                    no enough resource to save the information.
  @retval RETURN_ACCESS_DENIED      it is too late to invoke this interface
  @retval RETURN_NOT_STARTED        it is too early to invoke this interface
  @retval RETURN_UNSUPPORTED        the service is not supported by implementaion.
**/
RETURN_STATUS
EFIAPI
UpdateLockBox (
  IN  GUID                        *Guid,
  IN  UINTN                       Offset,
  IN  VOID                        *Buffer,
  IN  UINTN                       Length
  )
{
  SMM_LOCK_BOX_DATA             *LockBox;
  EFI_PHYSICAL_ADDRESS          SmramBuffer;
  EFI_STATUS                    Status;

  DEBUG ((DEBUG_INFO, "SmmLockBoxSmmLib UpdateLockBox - Enter\n"));

  //
  // Basic check
  //
  if ((Guid == NULL) || (Buffer == NULL) || (Length == 0) ||
      (Length > MAX_UINTN - Offset)) {
    DEBUG ((DEBUG_INFO, "SmmLockBoxSmmLib UpdateLockBox - Exit (%r)\n", EFI_INVALID_PARAMETER));
    return EFI_INVALID_PARAMETER;
  }

  //
  // Find LockBox
  //
  LockBox = InternalFindLockBoxByGuid (Guid);
  if (LockBox == NULL) {
    DEBUG ((DEBUG_INFO, "SmmLockBoxSmmLib UpdateLockBox - Exit (%r)\n", EFI_NOT_FOUND));
    return EFI_NOT_FOUND;
  }

  //
  // Update data
  //
  if (LockBox->Length < Offset + Length) {
    if ((LockBox->Attributes & LOCK_BOX_ATTRIBUTE_RESTORE_IN_S3_ONLY) != 0) {
      //
      // If 'LOCK_BOX_ATTRIBUTE_RESTORE_IN_S3_ONLY' attribute is set, enlarge the
      // LockBox.
      //
      DEBUG ((
        DEBUG_INFO,
        "SmmLockBoxSmmLib UpdateLockBox - Origin LockBox too small, enlarge.\n"
        ));

      if (EFI_PAGES_TO_SIZE (EFI_SIZE_TO_PAGES ((UINTN)LockBox->Length)) < Offset + Length) {
        //
        // In SaveLockBox(), the SMRAM buffer allocated for LockBox is of page
        // granularity. Here, if the required size is larger than the origin size
        // of the pages, allocate new buffer from SMRAM to enlarge the LockBox.
        //
        DEBUG ((
          DEBUG_INFO,
          "SmmLockBoxSmmLib UpdateLockBox - Allocate new buffer to enlarge.\n"
          ));
        Status = gSmst->SmmAllocatePages (
                          AllocateAnyPages,
                          EfiRuntimeServicesData,
                          EFI_SIZE_TO_PAGES (Offset + Length),
                          &SmramBuffer
                          );
        if (EFI_ERROR (Status)) {
          DEBUG ((DEBUG_INFO, "SmmLockBoxSmmLib UpdateLockBox - Exit (%r)\n", EFI_OUT_OF_RESOURCES));
          return EFI_OUT_OF_RESOURCES;
        }

        //
        // Copy origin data to the new SMRAM buffer and wipe the content in the
        // origin SMRAM buffer.
        //
        CopyMem ((VOID *)(UINTN)SmramBuffer, (VOID *)(UINTN)LockBox->SmramBuffer, (UINTN)LockBox->Length);
        ZeroMem ((VOID *)(UINTN)LockBox->SmramBuffer, (UINTN)LockBox->Length);
        gSmst->SmmFreePages (LockBox->SmramBuffer, EFI_SIZE_TO_PAGES ((UINTN)LockBox->Length));

        LockBox->SmramBuffer = SmramBuffer;
      }

      //
      // Handle uninitialized content in the LockBox.
      //
      if (Offset > LockBox->Length) {
        ZeroMem (
          (VOID *)((UINTN)LockBox->SmramBuffer + (UINTN)LockBox->Length),
          Offset - (UINTN)LockBox->Length
          );
      }
      LockBox->Length = Offset + Length;
    } else {
      //
      // If 'LOCK_BOX_ATTRIBUTE_RESTORE_IN_S3_ONLY' attribute is NOT set, return
      // EFI_BUFFER_TOO_SMALL directly.
      //
      DEBUG ((DEBUG_INFO, "SmmLockBoxSmmLib UpdateLockBox - Exit (%r)\n", EFI_BUFFER_TOO_SMALL));
      return EFI_BUFFER_TOO_SMALL;
    }
  }
  ASSERT ((UINTN)LockBox->SmramBuffer <= (MAX_ADDRESS - Offset));
  CopyMem ((VOID *)((UINTN)LockBox->SmramBuffer + Offset), Buffer, Length);

  //
  // Done
  //
  DEBUG ((DEBUG_INFO, "SmmLockBoxSmmLib UpdateLockBox - Exit (%r)\n", EFI_SUCCESS));
  return EFI_SUCCESS;
}

/**
  This function will restore confidential information from lockbox.

  @param Guid   the guid to identify the confidential information
  @param Buffer the address of the restored confidential information
                NULL means restored to original address, Length MUST be NULL at same time.
  @param Length the length of the restored confidential information

  @retval RETURN_SUCCESS            the information is restored successfully.
  @retval RETURN_INVALID_PARAMETER  the Guid is NULL, or one of Buffer and Length is NULL.
  @retval RETURN_WRITE_PROTECTED    Buffer and Length are NULL, but the LockBox has no
                                    LOCK_BOX_ATTRIBUTE_RESTORE_IN_PLACE attribute.
  @retval RETURN_BUFFER_TOO_SMALL   the Length is too small to hold the confidential information.
  @retval RETURN_NOT_FOUND          the requested GUID not found.
  @retval RETURN_NOT_STARTED        it is too early to invoke this interface
  @retval RETURN_ACCESS_DENIED      not allow to restore to the address
  @retval RETURN_UNSUPPORTED        the service is not supported by implementaion.
**/
RETURN_STATUS
EFIAPI
RestoreLockBox (
  IN  GUID                        *Guid,
  IN  VOID                        *Buffer, OPTIONAL
  IN  OUT UINTN                   *Length  OPTIONAL
  )
{
  SMM_LOCK_BOX_DATA              *LockBox;
  VOID                           *RestoreBuffer;

  DEBUG ((DEBUG_INFO, "SmmLockBoxSmmLib RestoreLockBox - Enter\n"));

  //
  // Restore this, Buffer and Length MUST be both NULL or both non-NULL
  //
  if ((Guid == NULL) ||
      ((Buffer == NULL) && (Length != NULL)) ||
      ((Buffer != NULL) && (Length == NULL))) {
    DEBUG ((DEBUG_INFO, "SmmLockBoxSmmLib RestoreLockBox - Exit (%r)\n", EFI_INVALID_PARAMETER));
    return EFI_INVALID_PARAMETER;
  }

  //
  // Find LockBox
  //
  LockBox = InternalFindLockBoxByGuid (Guid);
  if (LockBox == NULL) {
    //
    // Not found
    //
    DEBUG ((DEBUG_INFO, "SmmLockBoxSmmLib RestoreLockBox - Exit (%r)\n", EFI_NOT_FOUND));
    return EFI_NOT_FOUND;
  }

  if (((LockBox->Attributes & LOCK_BOX_ATTRIBUTE_RESTORE_IN_S3_ONLY) != 0) &&
      mSmmLockBoxSmmReadyToLock &&
      !mSmmLockBoxDuringS3Resume) {
    //
    // With LOCK_BOX_ATTRIBUTE_RESTORE_IN_S3_ONLY,
    // this LockBox can be restored in S3 resume only.
    //
    return EFI_ACCESS_DENIED;
  }

  //
  // Set RestoreBuffer
  //
  if (Buffer != NULL) {
    //
    // restore to new buffer
    //
    RestoreBuffer = Buffer;
  } else {
    //
    // restore to original buffer
    //
    if ((LockBox->Attributes & LOCK_BOX_ATTRIBUTE_RESTORE_IN_PLACE) == 0) {
      DEBUG ((DEBUG_INFO, "SmmLockBoxSmmLib RestoreLockBox - Exit (%r)\n", EFI_WRITE_PROTECTED));
      return EFI_WRITE_PROTECTED;
    }
    RestoreBuffer = (VOID *)(UINTN)LockBox->Buffer;
  }

  //
  // Set RestoreLength
  //
  if (Length != NULL) {
    if (*Length < (UINTN)LockBox->Length) {
      //
      // Input buffer is too small to hold all data.
      //
      *Length = (UINTN)LockBox->Length;
      DEBUG ((DEBUG_INFO, "SmmLockBoxSmmLib RestoreLockBox - Exit (%r)\n", EFI_BUFFER_TOO_SMALL));
      return EFI_BUFFER_TOO_SMALL;
    }
    *Length = (UINTN)LockBox->Length;
  }

  //
  // Restore data
  //
  CopyMem (RestoreBuffer, (VOID *)(UINTN)LockBox->SmramBuffer, (UINTN)LockBox->Length);

  //
  // Done
  //
  DEBUG ((DEBUG_INFO, "SmmLockBoxSmmLib RestoreLockBox - Exit (%r)\n", EFI_SUCCESS));
  return EFI_SUCCESS;
}

/**
  This function will restore confidential information from all lockbox which have RestoreInPlace attribute.

  @retval RETURN_SUCCESS            the information is restored successfully.
  @retval RETURN_NOT_STARTED        it is too early to invoke this interface
  @retval RETURN_UNSUPPORTED        the service is not supported by implementaion.
**/
RETURN_STATUS
EFIAPI
RestoreAllLockBoxInPlace (
  VOID
  )
{
  SMM_LOCK_BOX_DATA             *LockBox;
  LIST_ENTRY                    *Link;
  LIST_ENTRY                    *LockBoxQueue;

  DEBUG ((DEBUG_INFO, "SmmLockBoxSmmLib RestoreAllLockBoxInPlace - Enter\n"));

  LockBoxQueue = InternalGetLockBoxQueue ();
  ASSERT (LockBoxQueue != NULL);

  //
  // Restore all, Buffer and Length MUST be NULL
  //
  for (Link = LockBoxQueue->ForwardLink;
       Link != LockBoxQueue;
       Link = Link->ForwardLink) {
    LockBox = BASE_CR (
                Link,
                SMM_LOCK_BOX_DATA,
                Link
                );
    if ((LockBox->Attributes & LOCK_BOX_ATTRIBUTE_RESTORE_IN_PLACE) != 0) {
      //
      // Restore data
      //
      CopyMem ((VOID *)(UINTN)LockBox->Buffer, (VOID *)(UINTN)LockBox->SmramBuffer, (UINTN)LockBox->Length);
    }
  }
  //
  // Done
  //
  DEBUG ((DEBUG_INFO, "SmmLockBoxSmmLib RestoreAllLockBoxInPlace - Exit (%r)\n", EFI_SUCCESS));
  return EFI_SUCCESS;
}