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/** @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 <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_ */
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