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StandaloneMmPkg/Library: Install Variable Arch Protocol 

In a system implementing the variable store in MM, there are no variable
arch protocol and variable write arch protocol installed into the
DXE_SMM protocol database. On such systems, it is not required to
locate these protocols by the DXE runtime variable drivers because
it can be assumed that these protocols are already installed in the
MM context. But then such an implementation will deviate from the
existing traditional MM based variable driver implementation.

So in order to maintain consistency with the traditional MM variable
driver implementation, allow platforms to install these protocols into
the DXE protocol database but these protocol will not be consumed
by non-secure variable service runtime driver.

The Platform which uses StandaloneMM based secure variable storage
have to include this library

Example
In edk2-platforms/Platform/ARM/SgiPkg/SgiPlatform.dsc

  ArmPkg/Drivers/MmCommunicationDxe/MmCommunication.inf {
    <LibraryClasses>
      NULL|StandaloneMmPkg/Library/VariableMmDependency/VariableMmDependency.inf
  }

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Jagadeesh Ujja <jagadeesh.ujja@arm.com>
Acked-by "Yao, Jiewen" <jiewen.yao@intel.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
This commit is contained in:
Jagadeesh Ujja 2019-03-04 14:23:59 +05:30 committed by Ard Biesheuvel
parent 690d60c0ad
commit 326598e9b7
2 changed files with 99 additions and 0 deletions
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53
StandaloneMmPkg/Library/VariableMmDependency/VariableMmDependency.c Normal file
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@ -0,0 +1,53 @@
/** @file
Runtime DXE part corresponding to StanaloneMM variable module.
This module installs variable arch protocol and variable write arch protocol
to StandaloneMM runtime variable service.
Copyright (c) 2019, ARM Ltd. All rights reserved.
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 <Library/DebugLib.h>
#include <Library/UefiBootServicesTableLib.h>
/**
The constructor function installs variable arch protocol and variable
write arch protocol to StandaloneMM runtime variable service
@param ImageHandle The firmware allocated handle for the EFI image.
@param SystemTable A pointer to the Management mode System Table.
@retval EFI_SUCCESS The constructor always returns EFI_SUCCESS.
**/
EFI_STATUS
EFIAPI
VariableMmDependencyLibConstructor (
IN EFI_HANDLE ImageHandle,
IN EFI_SYSTEM_TABLE *SystemTable
)
{
EFI_STATUS Status;
EFI_HANDLE Handle;
Handle = NULL;
Status = gBS->InstallMultipleProtocolInterfaces (
&Handle,
&gEfiSmmVariableProtocolGuid,
NULL,
&gSmmVariableWriteGuid,
NULL,
NULL
);
ASSERT_EFI_ERROR (Status);
return EFI_SUCCESS;
}

46
StandaloneMmPkg/Library/VariableMmDependency/VariableMmDependency.inf Normal file
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## @file
# Runtime DXE part corresponding to StanaloneMM variable module.
#
# This module installs variable arch protocol and variable write arch protocol
# to StandaloneMM runtime variable service.
#
# Copyright (c) 2019, ARM Ltd. All rights reserved.
# 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.
#
##
[Defines]
INF_VERSION = 0x0001001A
BASE_NAME = VariableMmDependency
FILE_GUID = 64BC4129-778E-4867-BA07-13999A4DEC3F
MODULE_TYPE = DXE_DRIVER
LIBRARY_CLASS = NULL
CONSTRUCTOR = VariableMmDependencyLibConstructor
#
# The following information is for reference only and not required by the build tools.
#
# VALID_ARCHITECTURES = AARCH64
#
#
[Sources]
VariableMmDependency.c
[Packages]
MdePkg/MdePkg.dec
MdeModulePkg/MdeModulePkg.dec
[Protocols]
gEfiSmmVariableProtocolGuid ## PRODUCES
[Guids]
gSmmVariableWriteGuid ## PRODUCES ## GUID # Install protocol
[Depex]
TRUE