Re: 回复: [edk2-devel] [PATCH v1 2/2] MdeModulePkg: Variable: Introduce MM based variable read service in PEI
Kun Qin
kuqin12 at gmail.com
Mon Jun 26 20:10:58 UTC 2023
Hi Liming,
Thanks for catching that. I have removed the PCD usage and resend the
patch here:
https://edk2.groups.io/g/devel/message/106372
Could you please let me know if you have any other feedback?
Per your functionality question, yes, the functionality was verified on
both virtual
and physical ARM platforms. I also added this statement to the v2 cover
letter.
Thanks,
Kun
On 6/24/2023 7:23 PM, gaoliming via groups.io wrote:
> Kun:
> Seemly, PcdMaxVariableSize is not used by this module. It can be removed.
>
> And, has its functionality been verified in the real platform?
>
> Thanks
> Liming
>> -----邮件原件-----
>> 发件人: devel at edk2.groups.io <devel at edk2.groups.io> 代表 Kun Qin
>> 发送时间: 2023年6月9日 4:45
>> 收件人: devel at edk2.groups.io
>> 抄送: Hao A Wu <hao.a.wu at intel.com>; Liming Gao
>> <gaoliming at byosoft.com.cn>; Jian J Wang <jian.j.wang at intel.com>; Ronny
>> Hansen <hansen.ronny at microsoft.com>; Shriram Masanamuthu
>> Chinnathurai <shriramma at microsoft.com>; Preshit Harlikar
>> <pharlikar at microsoft.com>
>> 主题: [edk2-devel] [PATCH v1 2/2] MdeModulePkg: Variable: Introduce MM
>> based variable read service in PEI
>>
>> From: Kun Qin <kuqin at microsoft.com>
>>
>> REF: https://bugzilla.tianocore.org/show_bug.cgi?id=4464
>>
>> This change introduced the Standalone MM based variable read capability
>> in PEI phase for applicable platforms (such as ARM platforms).
>>
>> Similar to the x86 counterpart, MM communicate PPI is used to request
>> variable information from Standalone MM environment.
>>
>> Cc: Hao A Wu <hao.a.wu at intel.com>
>> Cc: Liming Gao <gaoliming at byosoft.com.cn>
>> Cc: Jian J Wang <jian.j.wang at intel.com>
>>
>> Co-authored-by: Ronny Hansen <hansen.ronny at microsoft.com>
>> Co-authored-by: Shriram Masanamuthu Chinnathurai
>> <shriramma at microsoft.com>
>> Co-authored-by: Preshit Harlikar <pharlikar at microsoft.com>
>> Signed-off-by: Kun Qin <kuqin at microsoft.com>
>> ---
>> MdeModulePkg/Universal/Variable/MmVariablePei/MmVariablePei.c |
>> 381 ++++++++++++++++++++
>> MdeModulePkg/MdeModulePkg.dsc
>> | 1 +
>> MdeModulePkg/Universal/Variable/MmVariablePei/MmVariablePei.h |
>> 134 +++++++
>> MdeModulePkg/Universal/Variable/MmVariablePei/MmVariablePei.inf |
>> 43 +++
>> 4 files changed, 559 insertions(+)
>>
>> diff --git
>> a/MdeModulePkg/Universal/Variable/MmVariablePei/MmVariablePei.c
>> b/MdeModulePkg/Universal/Variable/MmVariablePei/MmVariablePei.c
>> new file mode 100644
>> index 000000000000..4f937e22e89e
>> --- /dev/null
>> +++ b/MdeModulePkg/Universal/Variable/MmVariablePei/MmVariablePei.c
>> @@ -0,0 +1,381 @@
>> +/** @file -- MmVariablePei.c
>>
>> + Provides interface for reading Secure System Variables during PEI.
>>
>> +
>>
>> + Copyright (c) 2006 - 2019, Intel Corporation. All rights reserved.<BR>
>>
>> + Copyright (c) Microsoft Corporation.<BR>
>>
>> + SPDX-License-Identifier: BSD-2-Clause-Patent
>>
>> +**/
>>
>> +
>>
>> +#include "MmVariablePei.h"
>>
>> +
>>
>> +#define MM_VARIABLE_COMM_BUFFER_OFFSET
>> (SMM_COMMUNICATE_HEADER_SIZE +
>> SMM_VARIABLE_COMMUNICATE_HEADER_SIZE)
>>
>> +
>>
>> +//
>>
>> +// Module globals
>>
>> +//
>>
>> +EFI_PEI_READ_ONLY_VARIABLE2_PPI mPeiSecureVariableRead = {
>>
>> + PeiMmGetVariable,
>>
>> + PeiMmGetNextVariableName
>>
>> +};
>>
>> +
>>
>> +EFI_PEI_PPI_DESCRIPTOR mPeiMmVariablePpi = {
>>
>> + (EFI_PEI_PPI_DESCRIPTOR_PPI |
>> EFI_PEI_PPI_DESCRIPTOR_TERMINATE_LIST),
>>
>> + &gEfiPeiReadOnlyVariable2PpiGuid,
>>
>> + &mPeiSecureVariableRead
>>
>> +};
>>
>> +
>>
>> +/**
>>
>> + 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
>>
>> + )
>>
>> +{
>>
>> + return PeiServicesInstallPpi (&mPeiMmVariablePpi);
>>
>> +}
>>
>> +
>>
>> +/**
>>
>> + Helper function to populate MM communicate header and variable
>> communicate header
>>
>> + and then communicate to PEI.
>>
>> +
>>
>> + @param[in, out] CommunicateBuffer Size of the variable name.
>>
>> + @param[in] CommunicateBufferSize The entire buffer size to be
>> sent to MM.
>>
>> + @param[in] Function The MM variable function
>> value.
>>
>> +
>>
>> + @retval EFI_INVALID_PARAMETER Invalid parameter.
>>
>> + @retval EFI_SUCCESS Find the specified variable.
>>
>> + @retval Others Errors returned by MM
>> communicate or variable service.
>>
>> +
>>
>> +**/
>>
>> +EFI_STATUS
>>
>> +PopulateHeaderAndCommunicate (
>>
>> + IN OUT UINT8 *CommunicateBuffer,
>>
>> + IN UINTN CommunicateBufferSize,
>>
>> + IN UINTN Function
>>
>> + )
>>
>> +{
>>
>> + EFI_STATUS Status;
>>
>> + EFI_PEI_MM_COMMUNICATION_PPI *MmCommunicationPpi;
>>
>> + EFI_MM_COMMUNICATE_HEADER *MmCommunicateHeader;
>>
>> + SMM_VARIABLE_COMMUNICATE_HEADER *MmVarCommsHeader;
>>
>> +
>>
>> + // Minimal sanity check
>>
>> + if ((CommunicateBuffer == NULL) ||
>>
>> + (CommunicateBufferSize <
>> MM_VARIABLE_COMM_BUFFER_OFFSET))
>>
>> + {
>>
>> + Status = EFI_INVALID_PARAMETER;
>>
>> + DEBUG ((DEBUG_ERROR, "%a: Invalid incoming parameters: %p and
>> 0x%x\n", __func__, CommunicateBuffer, CommunicateBufferSize));
>>
>> + goto Exit;
>>
>> + }
>>
>> +
>>
>> + if ((Function !=
>> SMM_VARIABLE_FUNCTION_GET_NEXT_VARIABLE_NAME) &&
>>
>> + (Function != SMM_VARIABLE_FUNCTION_GET_VARIABLE))
>>
>> + {
>>
>> + Status = EFI_INVALID_PARAMETER;
>>
>> + DEBUG ((DEBUG_ERROR, "%a: Invalid function value: 0x%x\n",
>> __func__, Function));
>>
>> + goto Exit;
>>
>> + }
>>
>> +
>>
>> + Status = PeiServicesLocatePpi (&gEfiPeiMmCommunicationPpiGuid, 0,
>> NULL, (VOID **)&MmCommunicationPpi);
>>
>> + if (EFI_ERROR (Status)) {
>>
>> + DEBUG ((DEBUG_ERROR, "%a: Failed to locate PEI MM Communication
>> PPI: %r\n", __func__, Status));
>>
>> + goto Exit;
>>
>> + }
>>
>> +
>>
>> + // Zero the entire Communication Buffer Header
>>
>> + MmCommunicateHeader = (EFI_MM_COMMUNICATE_HEADER
>> *)CommunicateBuffer;
>>
>> +
>>
>> + ZeroMem (MmCommunicateHeader,
>> SMM_COMMUNICATE_HEADER_SIZE);
>>
>> +
>>
>> + // Use gEfiSmmVariableProtocolGuid to request the MM variable service
>> in Standalone MM
>>
>> + CopyMem ((VOID *)&MmCommunicateHeader->HeaderGuid,
>> &gEfiSmmVariableProtocolGuid, sizeof (GUID));
>>
>> +
>>
>> + // Program the MM header size
>>
>> + MmCommunicateHeader->MessageLength = CommunicateBufferSize -
>> SMM_COMMUNICATE_HEADER_SIZE;
>>
>> +
>>
>> + MmVarCommsHeader = (SMM_VARIABLE_COMMUNICATE_HEADER
>> *)(CommunicateBuffer + SMM_COMMUNICATE_HEADER_SIZE);
>>
>> +
>>
>> + // We are only supporting GetVariable and GetNextVariableName
>>
>> + MmVarCommsHeader->Function = Function;
>>
>> +
>>
>> + // Send the MM request using MmCommunicationPei
>>
>> + Status = MmCommunicationPpi->Communicate (MmCommunicationPpi,
>> CommunicateBuffer, &CommunicateBufferSize);
>>
>> + if (EFI_ERROR (Status)) {
>>
>> + // Received an error from MM interface.
>>
>> + DEBUG ((DEBUG_ERROR, "%a - MM Interface Error: %r\n", __func__,
>> Status));
>>
>> + goto Exit;
>>
>> + }
>>
>> +
>>
>> + // MM request was successfully handled by the framework.
>>
>> + // Set status to the Variable Service Status Code
>>
>> + Status = MmVarCommsHeader->ReturnStatus;
>>
>> + if (EFI_ERROR (Status)) {
>>
>> + // We received an error from Variable Service.
>>
>> + // We cant do anymore so return Status
>>
>> + if (Status != EFI_BUFFER_TOO_SMALL) {
>>
>> + DEBUG ((DEBUG_ERROR, "%a - Variable Service Error: %r\n",
>> __func__, Status));
>>
>> + }
>>
>> +
>>
>> + goto Exit;
>>
>> + }
>>
>> +
>>
>> +Exit:
>>
>> + return Status;
>>
>> +}
>>
>> +
>>
>> +/**
>>
>> + This service retrieves a variable's value using its name and GUID.
>>
>> +
>>
>> + 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.
>>
>> +
>>
>> + @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, OPTIONAL
>>
>> + IN OUT UINTN *DataSize,
>>
>> + OUT VOID *Data OPTIONAL
>>
>> + )
>>
>> +{
>>
>> + EFI_STATUS Status;
>>
>> + UINTN MessageSize;
>>
>> + SMM_VARIABLE_COMMUNICATE_ACCESS_VARIABLE
>> *MmVarAccessHeader;
>>
>> + UINT8
>> *MmCommunicateBuffer;
>>
>> + UINTN RequiredPages;
>>
>> +
>>
>> + // Check input parameters
>>
>> + if ((VariableName == NULL) || (VariableGuid == NULL) || (DataSize ==
>> NULL)) {
>>
>> + return EFI_INVALID_PARAMETER;
>>
>> + }
>>
>> +
>>
>> + if (VariableName[0] == 0) {
>>
>> + return EFI_NOT_FOUND;
>>
>> + }
>>
>> +
>>
>> + if ((*DataSize > 0) && (Data == NULL)) {
>>
>> + return EFI_INVALID_PARAMETER;
>>
>> + }
>>
>> +
>>
>> + // Allocate required pages to send MM request
>>
>> + MessageSize = MM_VARIABLE_COMM_BUFFER_OFFSET +
>>
>> + OFFSET_OF
>> (SMM_VARIABLE_COMMUNICATE_ACCESS_VARIABLE, Name) +
>>
>> + StrSize (VariableName) + *DataSize;
>>
>> +
>>
>> + RequiredPages = EFI_SIZE_TO_PAGES (MessageSize);
>>
>> + MmCommunicateBuffer = (UINT8 *)AllocatePages (RequiredPages);
>>
>> +
>>
>> + if (MmCommunicateBuffer == NULL) {
>>
>> + Status = EFI_OUT_OF_RESOURCES;
>>
>> + DEBUG ((DEBUG_ERROR, "%a: Failed to allocate memory: %r\n",
>> __func__, Status));
>>
>> + return Status;
>>
>> + }
>>
>> +
>>
>> + // Zero the entire Communication Buffer
>>
>> + ZeroMem (MmCommunicateBuffer, (RequiredPages * EFI_PAGE_SIZE));
>>
>> +
>>
>> + //
>>
>> + // Program all payload structure contents
>>
>> + //
>>
>> + MmVarAccessHeader =
>> (SMM_VARIABLE_COMMUNICATE_ACCESS_VARIABLE
>> *)(MmCommunicateBuffer + MM_VARIABLE_COMM_BUFFER_OFFSET);
>>
>> +
>>
>> + // Variable GUID
>>
>> + CopyMem ((VOID *)&MmVarAccessHeader->Guid, VariableGuid, sizeof
>> (GUID));
>>
>> +
>>
>> + // Program the max amount of data we accept.
>>
>> + MmVarAccessHeader->DataSize = *DataSize;
>>
>> +
>>
>> + // Get size of the variable name
>>
>> + MmVarAccessHeader->NameSize = StrSize (VariableName);
>>
>> +
>>
>> + // Populate incoming variable name
>>
>> + CopyMem ((VOID *)&MmVarAccessHeader->Name, VariableName,
>> MmVarAccessHeader->NameSize);
>>
>> +
>>
>> + Status = PopulateHeaderAndCommunicate (MmCommunicateBuffer,
>> MessageSize, SMM_VARIABLE_FUNCTION_GET_VARIABLE);
>>
>> + if (EFI_ERROR (Status)) {
>>
>> + // We received an error from either communicate or Variable Service.
>>
>> + if (Status != EFI_BUFFER_TOO_SMALL) {
>>
>> + DEBUG ((DEBUG_ERROR, "%a - Communite to MM for variable
>> service errored: %r\n", __func__, Status));
>>
>> + }
>>
>> +
>>
>> + goto Exit;
>>
>> + }
>>
>> +
>>
>> + Status = EFI_SUCCESS;
>>
>> +
>>
>> + // User provided buffer is too small
>>
>> + if (*DataSize < MmVarAccessHeader->DataSize) {
>>
>> + Status = EFI_BUFFER_TOO_SMALL;
>>
>> + }
>>
>> +
>>
>> +Exit:
>>
>> + // Check if we need to set Attributes
>>
>> + if (Attributes != NULL) {
>>
>> + *Attributes = MmVarAccessHeader->Attributes;
>>
>> + }
>>
>> +
>>
>> + *DataSize = MmVarAccessHeader->DataSize;
>>
>> +
>>
>> + if (Status == EFI_SUCCESS) {
>>
>> + CopyMem ((VOID *)Data, (UINT8 *)MmVarAccessHeader->Name +
>> MmVarAccessHeader->NameSize, *DataSize);
>>
>> + }
>>
>> +
>>
>> + // Free the Communication Buffer
>>
>> + if (MmCommunicateBuffer != NULL) {
>>
>> + FreePages (MmCommunicateBuffer, RequiredPages);
>>
>> + }
>>
>> +
>>
>> + return Status;
>>
>> +}
>>
>> +
>>
>> +/**
>>
>> + 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
>>
>> + )
>>
>> +{
>>
>> + EFI_STATUS Status;
>>
>> + UINTN
>> MessageSize;
>>
>> + UINT8
>> *MmCommunicateBuffer;
>>
>> + SMM_VARIABLE_COMMUNICATE_GET_NEXT_VARIABLE_NAME
>> *MmVarGetNextVarHeader;
>>
>> + UINTN
>> RequiredPages;
>>
>> +
>>
>> + // Check input parameters
>>
>> + if ((VariableName == NULL) ||
>>
>> + (VariableGuid == NULL) ||
>>
>> + (VariableNameSize == NULL) ||
>>
>> + (*VariableNameSize == 0))
>>
>> + {
>>
>> + return EFI_INVALID_PARAMETER;
>>
>> + }
>>
>> +
>>
>> + // Allocate required pages to send MM request
>>
>> + MessageSize = MM_VARIABLE_COMM_BUFFER_OFFSET +
>>
>> + OFFSET_OF
>> (SMM_VARIABLE_COMMUNICATE_ACCESS_VARIABLE, Name) +
>>
>> + StrSize (VariableName) + *VariableNameSize;
>>
>> +
>>
>> + RequiredPages = EFI_SIZE_TO_PAGES (MessageSize);
>>
>> + MmCommunicateBuffer = (UINT8 *)AllocatePages (RequiredPages);
>>
>> +
>>
>> + if (MmCommunicateBuffer == NULL) {
>>
>> + Status = EFI_OUT_OF_RESOURCES;
>>
>> + DEBUG ((DEBUG_ERROR, "%a: Failed to allocate memory: %r\n",
>> __func__, Status));
>>
>> + return Status;
>>
>> + }
>>
>> +
>>
>> + // Zero the entire Communication Buffer
>>
>> + ZeroMem (MmCommunicateBuffer, (RequiredPages * EFI_PAGE_SIZE));
>>
>> +
>>
>> + //
>>
>> + // Program all payload structure contents
>>
>> + //
>>
>> + MmVarGetNextVarHeader =
>> (SMM_VARIABLE_COMMUNICATE_GET_NEXT_VARIABLE_NAME
>> *)(MmCommunicateBuffer + MM_VARIABLE_COMM_BUFFER_OFFSET);
>>
>> +
>>
>> + // Variable GUID
>>
>> + CopyMem ((VOID *)&MmVarGetNextVarHeader->Guid, VariableGuid,
>> sizeof (GUID));
>>
>> +
>>
>> + // Program the maximal length of name we can accept.
>>
>> + MmVarGetNextVarHeader->NameSize = *VariableNameSize;
>>
>> +
>>
>> + // Populate incoming variable name
>>
>> + CopyMem ((VOID *)&MmVarGetNextVarHeader->Name, VariableName,
>> MmVarGetNextVarHeader->NameSize);
>>
>> +
>>
>> + // Send the MM request using MmCommunicationPei
>>
>> + Status = PopulateHeaderAndCommunicate (MmCommunicateBuffer,
>> MessageSize, SMM_VARIABLE_FUNCTION_GET_NEXT_VARIABLE_NAME);
>>
>> + if (EFI_ERROR (Status)) {
>>
>> + // We received an error from either communicate or Variable Service.
>>
>> + if (Status != EFI_BUFFER_TOO_SMALL) {
>>
>> + DEBUG ((DEBUG_ERROR, "%a - Communite to MM for variable
>> service errored: %r\n", __func__, Status));
>>
>> + }
>>
>> +
>>
>> + goto Exit;
>>
>> + }
>>
>> +
>>
>> + Status = EFI_SUCCESS;
>>
>> +
>>
>> + // User provided buffer is too small
>>
>> + if (*VariableNameSize < MmVarGetNextVarHeader->NameSize) {
>>
>> + Status = EFI_BUFFER_TOO_SMALL;
>>
>> + }
>>
>> +
>>
>> +Exit:
>>
>> + // Update the name size to be returned
>>
>> + *VariableNameSize = MmVarGetNextVarHeader->NameSize;
>>
>> +
>>
>> + if (Status == EFI_SUCCESS) {
>>
>> + CopyMem ((VOID *)VariableName, (UINT8
>> *)MmVarGetNextVarHeader->Name, *VariableNameSize);
>>
>> + CopyMem ((VOID *)VariableGuid, (UINT8
>> *)&(MmVarGetNextVarHeader->Guid), sizeof (EFI_GUID));
>>
>> + }
>>
>> +
>>
>> + // Free the Communication Buffer
>>
>> + if (MmCommunicateBuffer != NULL) {
>>
>> + FreePages (MmCommunicateBuffer, RequiredPages);
>>
>> + }
>>
>> +
>>
>> + return Status;
>>
>> +}
>>
>> diff --git a/MdeModulePkg/MdeModulePkg.dsc
>> b/MdeModulePkg/MdeModulePkg.dsc
>> index 5b1f50e9c084..1aedfe280ae1 100644
>> --- a/MdeModulePkg/MdeModulePkg.dsc
>> +++ b/MdeModulePkg/MdeModulePkg.dsc
>> @@ -400,6 +400,7 @@ [Components]
>> MdeModulePkg/Application/VariableInfo/VariableInfo.inf
>>
>>
>> MdeModulePkg/Universal/FaultTolerantWritePei/FaultTolerantWritePei.inf
>>
>> MdeModulePkg/Universal/Variable/Pei/VariablePei.inf
>>
>> + MdeModulePkg/Universal/Variable/MmVariablePei/MmVariablePei.inf
>>
>> MdeModulePkg/Universal/WatchdogTimerDxe/WatchdogTimer.inf
>>
>> MdeModulePkg/Universal/TimestampDxe/TimestampDxe.inf
>>
>>
>> MdeModulePkg/Universal/FaultTolerantWriteDxe/FaultTolerantWriteDxe.inf
>>
>> diff --git
>> a/MdeModulePkg/Universal/Variable/MmVariablePei/MmVariablePei.h
>> b/MdeModulePkg/Universal/Variable/MmVariablePei/MmVariablePei.h
>> new file mode 100644
>> index 000000000000..0feed8cd1cb6
>> --- /dev/null
>> +++ b/MdeModulePkg/Universal/Variable/MmVariablePei/MmVariablePei.h
>> @@ -0,0 +1,134 @@
>> +/** @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_COMMUNICAT
>> E_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_ */
>>
>> diff --git
>> a/MdeModulePkg/Universal/Variable/MmVariablePei/MmVariablePei.inf
>> b/MdeModulePkg/Universal/Variable/MmVariablePei/MmVariablePei.inf
>> new file mode 100644
>> index 000000000000..d122703e9b5d
>> --- /dev/null
>> +++ b/MdeModulePkg/Universal/Variable/MmVariablePei/MmVariablePei.inf
>> @@ -0,0 +1,43 @@
>> +## @file -- MmVariablePei.inf
>>
>> +# Provides interface for reading Secure System Variables during PEI.
>>
>> +#
>>
>> +# Copyright (c) Microsoft Corporation.
>>
>> +# SPDX-License-Identifier: BSD-2-Clause-Patent
>>
>> +##
>>
>> +
>>
>> +
>>
>> +[Defines]
>>
>> + INF_VERSION = 0x00010005
>>
>> + BASE_NAME = MmVariablePei
>>
>> + FILE_GUID =
>> CD660A87-454B-4346-A35C-3D89BF8ECFAF
>>
>> + MODULE_TYPE = PEIM
>>
>> + VERSION_STRING = 1.0
>>
>> + ENTRY_POINT = PeiMmVariableInitialize
>>
>> +
>>
>> +[Sources]
>>
>> + MmVariablePei.c
>>
>> + MmVariablePei.h
>>
>> +
>>
>> +[Packages]
>>
>> + MdePkg/MdePkg.dec
>>
>> + MdeModulePkg/MdeModulePkg.dec
>>
>> +
>>
>> +[LibraryClasses]
>>
>> + PcdLib
>>
>> + PeiServicesLib
>>
>> + PeimEntryPoint
>>
>> + MemoryAllocationLib
>>
>> + HobLib
>>
>> +
>>
>> +[Pcd]
>>
>> + gEfiMdeModulePkgTokenSpaceGuid.PcdMaxVariableSize
>>
>> +
>>
>> +[Protocols]
>>
>> + gEfiSmmVariableProtocolGuid ## CONSUMES
>>
>> +
>>
>> +[Ppis]
>>
>> + gEfiPeiReadOnlyVariable2PpiGuid ## PRODUCES
>>
>> + gEfiPeiMmCommunicationPpiGuid ## CONSUMES
>>
>> +
>>
>> +[Depex]
>>
>> + gEfiPeiMmCommunicationPpiGuid
>>
>> --
>> 2.40.1.windows.1
>>
>>
>>
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>>
>
>
>
>
>
>
>
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