MdeModulePkg/Universal/Variable/MmVariablePei/MmVariablePei.h

/** @file -- MmVariablePei.h
  Provides interface for reading Secure System Variables during PEI.

  Copyright (c) Microsoft Corporation.
  SPDX-License-Identifier: BSD-2-Clause-Patent
**/

#ifndef PEI_MM_VARIABLE_LIB_H_
#define PEI_MM_VARIABLE_LIB_H_

#include <PiPei.h>
#include <Uefi/UefiSpec.h>

#include <Library/DebugLib.h>
#include <Library/PcdLib.h>
#include <Library/BaseMemoryLib.h>
#include <Library/PeimEntryPoint.h>
#include <Library/PeiServicesLib.h>
#include <Library/MemoryAllocationLib.h>
#include <Library/HobLib.h>

#include <Guid/SmmVariableCommon.h>

#include <Ppi/ReadOnlyVariable2.h>
#include <Ppi/MmCommunication.h>
#include <Ppi/MmCommunication3.h>

#include <Protocol/SmmVariable.h>
#include <Protocol/MmCommunication.h>

/**
  Entry point of PEI Secure Variable read driver

  @param  FileHandle   Handle of the file being invoked.
                       Type EFI_PEI_FILE_HANDLE is defined in FfsFindNextFile().
  @param  PeiServices  General purpose services available to every PEIM.

  @retval EFI_SUCCESS  If the interface could be successfully installed
  @retval Others       Returned from PeiServicesInstallPpi()
**/
EFI_STATUS
EFIAPI
PeiMmVariableInitialize (
  IN       EFI_PEI_FILE_HANDLE  FileHandle,
  IN CONST EFI_PEI_SERVICES     **PeiServices
  );

/**

  This function enables the read of Secure Variables during PEI.

  This function is using the Secure Variable Store.If the Data
  buffer is too small to hold the contents of the variable, the error
  EFI_BUFFER_TOO_SMALL is returned and DataSize is set to the required buffer
  size to obtain the data.

  The function performs the following:

  1) Creates an MM request
  2) Fills out the following data structures for the Secure Variable Service
      SMM_VARIABLE_COMMUNICATE_HEADER/SMM_VARIABLE_COMMUNICATE_ACCESS_VARIABLE
  3) Adds the MM data structures to the MM request.
  4) Sends the MM request to EL3 using MmCommunicationPeiLib.
  5) The MM request is sent to S-EL0.
  6) The MM request is then handled by the registered handler with GUID: gEfiSmmVariableProtocolGuid

  @param  This                  A pointer to this instance of the EFI_PEI_READ_ONLY_VARIABLE2_PPI.
  @param  VariableName          A pointer to a null-terminated string that is the variable's name.
  @param  VariableGuid          A pointer to an EFI_GUID that is the variable's GUID. The combination of
                                VariableGuid and VariableName must be unique.
  @param  Attributes            If non-NULL, on return, points to the variable's attributes.
  @param  DataSize              On entry, points to the size in bytes of the Data buffer.
                                On return, points to the size of the data returned in Data.
  @param  Data                  Points to the buffer which will hold the returned variable value.
                                May be NULL with a zero DataSize in order to determine the size of the buffer needed.

  @retval EFI_SUCCESS           The variable was read successfully.
  @retval EFI_NOT_FOUND         The variable was not found.
  @retval EFI_BUFFER_TOO_SMALL  The DataSize is too small for the resulting data.
                                DataSize is updated with the size required for
                                the specified variable.
  @retval EFI_INVALID_PARAMETER VariableName, VariableGuid, DataSize or Data is NULL.
  @retval EFI_DEVICE_ERROR      The variable could not be retrieved because of a device error.

**/
EFI_STATUS
EFIAPI
PeiMmGetVariable (
  IN CONST  EFI_PEI_READ_ONLY_VARIABLE2_PPI  *This,
  IN CONST  CHAR16                           *VariableName,
  IN CONST  EFI_GUID                         *VariableGuid,
  OUT       UINT32                           *Attributes,
  IN OUT    UINTN                            *DataSize,
  OUT       VOID                             *Data OPTIONAL
  );

/**
  Return the next variable name and GUID.

  This function is called multiple times to retrieve the VariableName
  and VariableGuid of all variables currently available in the system.
  On each call, the previous results are passed into the interface,
  and, on return, the interface returns the data for the next
  interface. When the entire variable list has been returned,
  EFI_NOT_FOUND is returned.

  @param  This              A pointer to this instance of the EFI_PEI_READ_ONLY_VARIABLE2_PPI.

  @param  VariableNameSize  On entry, points to the size of the buffer pointed to by VariableName.
                            On return, the size of the variable name buffer.
  @param  VariableName      On entry, a pointer to a null-terminated string that is the variable's name.
                            On return, points to the next variable's null-terminated name string.

  @param  VariableGuid      On entry, a pointer to an EFI_GUID that is the variable's GUID.
                            On return, a pointer to the next variable's GUID.

  @retval EFI_SUCCESS           The variable was read successfully.
  @retval EFI_NOT_FOUND         The variable could not be found.
  @retval EFI_BUFFER_TOO_SMALL  The VariableNameSize is too small for the resulting
                                data. VariableNameSize is updated with the size
                                required for the specified variable.
  @retval EFI_INVALID_PARAMETER VariableName, VariableGuid or
                                VariableNameSize is NULL.
  @retval EFI_DEVICE_ERROR      The variable could not be retrieved because of a device error.
**/
EFI_STATUS
EFIAPI
PeiMmGetNextVariableName (
  IN CONST  EFI_PEI_READ_ONLY_VARIABLE2_PPI  *This,
  IN OUT UINTN                               *VariableNameSize,
  IN OUT CHAR16                              *VariableName,
  IN OUT EFI_GUID                            *VariableGuid
  );

#endif /* PEI_MM_VARIABLE_LIB_H_ */