Re: [EXTERNAL] Re: [edk2-devel] [PATCH v4 09/14] MdeModulePkg: Connect VariablePolicy business logic to VariableServices

["Laszlo Ersek" <lersek@redhat.com>]

On 06/02/20 20:17, Bret Barkelew wrote:
> Actually, two things:
> 
>   1.  I was running on the wrong branch and
>   2.  I don’t know that I submitted this series to GitHub yet, so the CI wouldn’t have caught it.

Ah OK -- I thought you had run the v4 series through a personal CI build
(= PR without the "push" label) on github.com.

(I don't closely monitor my github notifications folder just yet, i.e.
before we transition to github.com for good, and so I couldn't have
remembered either the presence or the absence of such a personal CI
build / PR in the recent past.)

Thanks!
Laszlo

> 
> I ran it through the Windows CI on my local machine before v4 patches, but VS is less picky (for better or [probably] worse) about things like EFIAPI and CONST.
> 
> I have these patched and ready for v5.
> 
> - Bret
> 
> From: Bret Barkelew via groups.io<mailto:bret.barkelew=microsoft.com@groups.io>
> Sent: Tuesday, June 2, 2020 9:55 AM
> To: devel@edk2.groups.io<mailto:devel@edk2.groups.io>; lersek@redhat.com<mailto:lersek@redhat.com>; bret@corthon.com<mailto:bret@corthon.com>
> Cc: Jian J Wang<mailto:jian.j.wang@intel.com>; Hao A Wu<mailto:hao.a.wu@intel.com>; liming.gao<mailto:liming.gao@intel.com>
> Subject: Re: [EXTERNAL] Re: [edk2-devel] [PATCH v4 09/14] MdeModulePkg: Connect VariablePolicy business logic to VariableServices
> 
> I’m also puzzled by the lack of error in CI. I just tried to leverage it to iterate on the problem and resolve the issue you’re seeing, but it wasn’t of any use. Will poke around a little, but also keen to hear from anyone with more GCC5 experience.
> 
> - Bret
> 
> From: Laszlo Ersek via groups.io<mailto:lersek=redhat.com@groups.io>
> Sent: Tuesday, June 2, 2020 8:48 AM
> To: devel@edk2.groups.io<mailto:devel@edk2.groups.io>; bret@corthon.com<mailto:bret@corthon.com>
> Cc: Jian J Wang<mailto:jian.j.wang@intel.com>; Hao A Wu<mailto:hao.a.wu@intel.com>; liming.gao<mailto:liming.gao@intel.com>
> Subject: [EXTERNAL] Re: [edk2-devel] [PATCH v4 09/14] MdeModulePkg: Connect VariablePolicy business logic to VariableServices
> 
> Hi Bret,
> 
> this patch causes a build failure with the GCC48 toolchain (actual
> version: gcc 4.8.5-36 in RHEL7), and also with the GCC5 toolchain
> (actual version: "Red Hat Cross 6.1.1-2"):
> 
> On 06/01/20 18:33, Bret Barkelew wrote:
>> https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fbugzilla.tianocore.org%2Fshow_bug.cgi%3Fid%3D2522&amp;data=02%7C01%7CBret.Barkelew%40microsoft.com%7C40552c2a4896475ed9da08d8070c6f51%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637267097285334746&amp;sdata=UEd%2FyUeixp5cq2jXwUQ68tIws9pbGBl0m9cpnrijaGc%3D&amp;reserved=0<https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fbugzilla.tianocore.org%2Fshow_bug.cgi%3Fid%3D2522&data=02%7C01%7Cbret.barkelew%40microsoft.com%7C35bc0a0f5b704d509a4808d80715cd2c%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637267137524542472&sdata=JpZVvrk4J3uqv8z5uCcR9DDLXSu0eL4Sm2UtffT9N3U%3D&reserved=0>
>>
>> VariablePolicy is an updated interface to
>> replace VarLock and VarCheckProtocol.
>>
>> Add connective code to publish the VariablePolicy protocol
>> and wire it to either the SMM communication interface
>> or directly into the VariablePolicyLib business logic.
>>
>> Cc: Jian J Wang <jian.j.wang@intel.com>
>> Cc: Hao A Wu <hao.a.wu@intel.com>
>> Cc: Liming Gao <liming.gao@intel.com>
>> Cc: Bret Barkelew <brbarkel@microsoft.com>
>> Signed-off-by: Bret Barkelew <brbarkel@microsoft.com>
>> ---
>>  MdeModulePkg/Universal/Variable/RuntimeDxe/VariableDxe.c             |  53 ++
>>  MdeModulePkg/Universal/Variable/RuntimeDxe/VariablePolicySmmDxe.c    | 642 ++++++++++++++++++++
>>  MdeModulePkg/Universal/Variable/RuntimeDxe/VariableSmmRuntimeDxe.c   |  14 +
>>  MdeModulePkg/Universal/Variable/RuntimeDxe/VariableRuntimeDxe.inf    |   2 +
>>  MdeModulePkg/Universal/Variable/RuntimeDxe/VariableSmm.inf           |   3 +
>>  MdeModulePkg/Universal/Variable/RuntimeDxe/VariableSmmRuntimeDxe.inf |  10 +
>>  6 files changed, 724 insertions(+)
>>
>> diff --git a/MdeModulePkg/Universal/Variable/RuntimeDxe/VariableDxe.c b/MdeModulePkg/Universal/Variable/RuntimeDxe/VariableDxe.c
>> index 7d2b6c8e1fad..d404d4763e54 100644
>> --- a/MdeModulePkg/Universal/Variable/RuntimeDxe/VariableDxe.c
>> +++ b/MdeModulePkg/Universal/Variable/RuntimeDxe/VariableDxe.c
>> @@ -5,18 +5,34 @@
>>  Copyright (C) 2013, Red Hat, Inc.
>>  Copyright (c) 2006 - 2019, Intel Corporation. All rights reserved.<BR>
>>  (C) Copyright 2015 Hewlett Packard Enterprise Development LP<BR>
>> +Copyright (c) Microsoft Corporation.
>>  SPDX-License-Identifier: BSD-2-Clause-Patent
>>
>>  **/
>>
>>  #include "Variable.h"
>>
>> +#include <Protocol/VariablePolicy.h>
>> +#include <Library/VariablePolicyLib.h>
>> +
>> +EFI_STATUS
>> +EFIAPI
>> +ProtocolIsVariablePolicyEnabled (
>> +  OUT BOOLEAN *State
>> +  );
>> +
>>  EFI_HANDLE                          mHandle                    = NULL;
>>  EFI_EVENT                           mVirtualAddressChangeEvent = NULL;
>>  VOID                                *mFtwRegistration          = NULL;
>>  VOID                                ***mVarCheckAddressPointer = NULL;
>>  UINTN                               mVarCheckAddressPointerCount = 0;
>>  EDKII_VARIABLE_LOCK_PROTOCOL        mVariableLock              = { VariableLockRequestToLock };
>> +EDKII_VARIABLE_POLICY_PROTOCOL      mVariablePolicyProtocol    = { EDKII_VARIABLE_POLICY_PROTOCOL_REVISION,
>> +                                                                    DisableVariablePolicy,
>> +                                                                    ProtocolIsVariablePolicyEnabled,
>> +                                                                    RegisterVariablePolicy,
> 
> (1) "error: initialization from incompatible pointer type [-Werror]"
> 
> That's because RegisterVariablePolicy() has the following prototype
> (from "MdeModulePkg/Include/Library/VariablePolicyLib.h"):
> 
>   EFI_STATUS
>   EFIAPI
>   RegisterVariablePolicy (
>     IN CONST VARIABLE_POLICY_ENTRY    *NewPolicy
>     );
> 
> whereas "EDKII_VARIABLE_POLICY_PROTOCOL.RegisterVariablePolicy" has the
> following type (from "MdeModulePkg/Include/Protocol/VariablePolicy.h"):
> 
>   typedef
>   EFI_STATUS
>   (EFIAPI *REGISTER_VARIABLE_POLICY)(
>     IN VARIABLE_POLICY_ENTRY *PolicyEntry
>     );
> 
> The latter does not take a pointer to CONST.
> 
> Now, assuming that "CONST is good", I locally modified the
> REGISTER_VARIABLE_POLICY typedef, just to see if that would allow the
> build to complete. It fixes problem (1), but it triggers a different
> problem:
> 
> 
>> +                                                                    DumpVariablePolicy,
>> +                                                                    LockVariablePolicy };
>>  EDKII_VAR_CHECK_PROTOCOL            mVarCheck                  = { VarCheckRegisterSetVariableCheckHandler,
>>                                                                      VarCheckVariablePropertySet,
>>                                                                      VarCheckVariablePropertyGet };
>> @@ -303,6 +319,8 @@ OnReadyToBoot (
>>      }
>>    }
>>
>> +  ASSERT_EFI_ERROR (LockVariablePolicy ());
>> +
>>    gBS->CloseEvent (Event);
>>  }
>>
>> @@ -466,6 +484,28 @@ FtwNotificationEvent (
>>  }
>>
>>
>> +/**
>> +  This API function returns whether or not the policy engine is
>> +  currently being enforced.
>> +
>> +  @param[out]   State       Pointer to a return value for whether the policy enforcement
>> +                            is currently enabled.
>> +
>> +  @retval     EFI_SUCCESS
>> +  @retval     Others        An error has prevented this command from completing.
>> +
>> +**/
>> +EFI_STATUS
>> +EFIAPI
>> +ProtocolIsVariablePolicyEnabled (
>> +  OUT BOOLEAN *State
>> +  )
>> +{
>> +  *State = IsVariablePolicyEnabled ();
>> +  return EFI_SUCCESS;
>> +}
>> +
>> +
>>  /**
>>    Variable Driver main entry point. The Variable driver places the 4 EFI
>>    runtime services in the EFI System Table and installs arch protocols
>> @@ -576,6 +616,19 @@ VariableServiceInitialize (
>>                    );
>>    ASSERT_EFI_ERROR (Status);
>>
>> +  // Register and initialize the VariablePolicy engine.
>> +  Status = InitVariablePolicyLib (VariableServiceGetVariable);
>> +  ASSERT_EFI_ERROR (Status);
>> +  Status = VarCheckRegisterSetVariableCheckHandler (ValidateSetVariable);
>> +  ASSERT_EFI_ERROR (Status);
>> +  Status = gBS->InstallMultipleProtocolInterfaces (
>> +                    &mHandle,
>> +                    &gEdkiiVariablePolicyProtocolGuid,
>> +                    &mVariablePolicyProtocol,
>> +                    NULL
>> +                    );
>> +  ASSERT_EFI_ERROR (Status);
>> +
>>    return EFI_SUCCESS;
>>  }
>>
>> diff --git a/MdeModulePkg/Universal/Variable/RuntimeDxe/VariablePolicySmmDxe.c b/MdeModulePkg/Universal/Variable/RuntimeDxe/VariablePolicySmmDxe.c
>> new file mode 100644
>> index 000000000000..3d799025983a
>> --- /dev/null
>> +++ b/MdeModulePkg/Universal/Variable/RuntimeDxe/VariablePolicySmmDxe.c
>> @@ -0,0 +1,642 @@
>> +/** @file -- VariablePolicySmmDxe.c
>> +This protocol allows communication with Variable Policy Engine.
>> +
>> +Copyright (c) Microsoft Corporation.
>> +SPDX-License-Identifier: BSD-2-Clause-Patent
>> +
>> +**/
>> +
>> +#include <Library/BaseLib.h>
>> +#include <Library/UefiLib.h>
>> +#include <Library/DebugLib.h>
>> +#include <Library/SafeIntLib.h>
>> +#include <Library/UefiBootServicesTableLib.h>
>> +#include <Library/BaseMemoryLib.h>
>> +#include <Library/MemoryAllocationLib.h>
>> +
>> +#include <Protocol/VariablePolicy.h>
>> +#include <Protocol/MmCommunication2.h>
>> +
>> +#include <Guid/VarCheckPolicyMmi.h>
>> +
>> +#include "Variable.h"
>> +
>> +EDKII_VARIABLE_POLICY_PROTOCOL  mVariablePolicyProtocol;
>> +EFI_MM_COMMUNICATION2_PROTOCOL  *mMmCommunication;
>> +
>> +VOID      *mMmCommunicationBuffer;
>> +UINTN     mMmCommunicationBufferSize;
>> +EFI_LOCK  mMmCommunicationLock;
>> +
>> +/**
>> +  Internal helper function to consolidate communication method.
>> +
>> +  @param[in,out]  CommBuffer
>> +  @param[in,out]  CommSize    Size of the CommBuffer.
>> +
>> +  @retval   EFI_STATUS    Result from communication method.
>> +
>> +**/
>> +STATIC
>> +EFI_STATUS
>> +InternalMmCommunicate (
>> +  IN OUT VOID             *CommBuffer,
>> +  IN OUT UINTN            *CommSize
>> +  )
>> +{
>> +  EFI_STATUS    Status;
>> +  if (CommBuffer == NULL || CommSize == NULL) {
>> +    return EFI_INVALID_PARAMETER;
>> +  }
>> +  Status = mMmCommunication->Communicate (mMmCommunication, CommBuffer, CommBuffer, CommSize);
>> +  return Status;
>> +}
>> +
>> +
>> +/**
>> +  This API function disables the variable policy enforcement. If it's
>> +  already been called once, will return EFI_ALREADY_STARTED.
>> +
>> +  @retval     EFI_SUCCESS
>> +  @retval     EFI_ALREADY_STARTED   Has already been called once this boot.
>> +  @retval     EFI_WRITE_PROTECTED   Interface has been locked until reboot.
>> +  @retval     EFI_WRITE_PROTECTED   Interface option is disabled by platform PCD.
>> +
>> +**/
>> +STATIC
>> +EFI_STATUS
>> +EFIAPI
>> +ProtocolDisableVariablePolicy (
>> +  VOID
>> +  )
>> +{
>> +  EFI_STATUS                    Status;
>> +  EFI_MM_COMMUNICATE_HEADER     *CommHeader;
>> +  VAR_CHECK_POLICY_COMM_HEADER  *PolicyHeader;
>> +  UINTN                         BufferSize;
>> +
>> +  // Check the PCD for convenience.
>> +  // This would also be rejected by the lib, but why go to MM if we don't have to?
>> +  if (!PcdGetBool (PcdAllowVariablePolicyEnforcementDisable)) {
>> +    return EFI_WRITE_PROTECTED;
>> +  }
>> +
>> +  AcquireLockOnlyAtBootTime (&mMmCommunicationLock);
>> +
>> +  // Set up the MM communication.
>> +  BufferSize    = mMmCommunicationBufferSize;
>> +  CommHeader    = mMmCommunicationBuffer;
>> +  PolicyHeader  = (VAR_CHECK_POLICY_COMM_HEADER*)&CommHeader->Data;
>> +  CopyGuid( &CommHeader->HeaderGuid, &gVarCheckPolicyLibMmiHandlerGuid );
>> +  CommHeader->MessageLength = BufferSize;
>> +  PolicyHeader->Signature   = VAR_CHECK_POLICY_COMM_SIG;
>> +  PolicyHeader->Revision    = VAR_CHECK_POLICY_COMM_REVISION;
>> +  PolicyHeader->Command     = VAR_CHECK_POLICY_COMMAND_DISABLE;
>> +
>> +  Status = InternalMmCommunicate (CommHeader, &BufferSize);
>> +  DEBUG(( DEBUG_VERBOSE, "%a - MmCommunication returned %r.\n", __FUNCTION__, Status ));
>> +
>> +  ReleaseLockOnlyAtBootTime (&mMmCommunicationLock);
>> +
>> +  return (EFI_ERROR( Status )) ? Status : PolicyHeader->Result;
>> +}
>> +
>> +
>> +/**
>> +  This API function returns whether or not the policy engine is
>> +  currently being enforced.
>> +
>> +  @param[out]   State       Pointer to a return value for whether the policy enforcement
>> +                            is currently enabled.
>> +
>> +  @retval     EFI_SUCCESS
>> +  @retval     Others        An error has prevented this command from completing.
>> +
>> +**/
>> +STATIC
>> +EFI_STATUS
>> +EFIAPI
>> +ProtocolIsVariablePolicyEnabled (
>> +  OUT BOOLEAN     *State
>> +  )
>> +{
>> +  EFI_STATUS                                Status;
>> +  EFI_MM_COMMUNICATE_HEADER                 *CommHeader;
>> +  VAR_CHECK_POLICY_COMM_HEADER              *PolicyHeader;
>> +  VAR_CHECK_POLICY_COMM_IS_ENABLED_PARAMS   *CommandParams;
>> +  UINTN                                     BufferSize;
>> +
>> +  if (State == NULL) {
>> +    return EFI_INVALID_PARAMETER;
>> +  }
>> +
>> +  AcquireLockOnlyAtBootTime (&mMmCommunicationLock);
>> +
>> +  // Set up the MM communication.
>> +  BufferSize    = mMmCommunicationBufferSize;
>> +  CommHeader    = mMmCommunicationBuffer;
>> +  PolicyHeader  = (VAR_CHECK_POLICY_COMM_HEADER*)&CommHeader->Data;
>> +  CommandParams = (VAR_CHECK_POLICY_COMM_IS_ENABLED_PARAMS*)(PolicyHeader + 1);
>> +  CopyGuid( &CommHeader->HeaderGuid, &gVarCheckPolicyLibMmiHandlerGuid );
>> +  CommHeader->MessageLength = BufferSize;
>> +  PolicyHeader->Signature   = VAR_CHECK_POLICY_COMM_SIG;
>> +  PolicyHeader->Revision    = VAR_CHECK_POLICY_COMM_REVISION;
>> +  PolicyHeader->Command     = VAR_CHECK_POLICY_COMMAND_IS_ENABLED;
>> +
>> +  Status = InternalMmCommunicate (CommHeader, &BufferSize);
>> +  DEBUG(( DEBUG_VERBOSE, "%a - MmCommunication returned %r.\n", __FUNCTION__, Status ));
>> +
>> +  if (!EFI_ERROR( Status )) {
>> +    Status = PolicyHeader->Result;
>> +    *State = CommandParams->State;
>> +  }
>> +
>> +  ReleaseLockOnlyAtBootTime (&mMmCommunicationLock);
>> +
>> +  return Status;
>> +}
>> +
>> +
>> +/**
>> +  This API function validates and registers a new policy with
>> +  the policy enforcement engine.
>> +
>> +  @param[in]  NewPolicy     Pointer to the incoming policy structure.
>> +
>> +  @retval     EFI_SUCCESS
>> +  @retval     EFI_INVALID_PARAMETER   NewPolicy is NULL or is internally inconsistent.
>> +  @retval     EFI_ALREADY_STARTED     An identical matching policy already exists.
>> +  @retval     EFI_WRITE_PROTECTED     The interface has been locked until the next reboot.
>> +  @retval     EFI_UNSUPPORTED         Policy enforcement has been disabled. No reason to add more policies.
>> +  @retval     EFI_ABORTED             A calculation error has prevented this function from completing.
>> +  @retval     EFI_OUT_OF_RESOURCES    Cannot grow the table to hold any more policies.
>> +
>> +**/
>> +STATIC
>> +EFI_STATUS
>> +EFIAPI
>> +ProtocolRegisterVariablePolicy (
>> +  IN VARIABLE_POLICY_ENTRY    *NewPolicy
>> +  )
>> +{
>> +  EFI_STATUS                                Status;
>> +  EFI_MM_COMMUNICATE_HEADER                 *CommHeader;
>> +  VAR_CHECK_POLICY_COMM_HEADER              *PolicyHeader;
>> +  VOID                                      *PolicyBuffer;
>> +  UINTN                                     BufferSize;
>> +  UINTN                                     RequiredSize;
>> +
>> +  if (NewPolicy == NULL) {
>> +    return EFI_INVALID_PARAMETER;
>> +  }
>> +
>> +  // First, make sure that the required size does not exceed the capabilities
>> +  // of the MmCommunication buffer.
>> +  RequiredSize = OFFSET_OF(EFI_MM_COMMUNICATE_HEADER, Data) + sizeof(VAR_CHECK_POLICY_COMM_HEADER);
>> +  Status = SafeUintnAdd( RequiredSize, NewPolicy->Size, &RequiredSize );
>> +  if (EFI_ERROR( Status ) || RequiredSize > mMmCommunicationBufferSize) {
>> +    DEBUG(( DEBUG_ERROR, "%a - Policy too large for buffer! %r, %d > %d \n", __FUNCTION__,
>> +            Status, RequiredSize, mMmCommunicationBufferSize ));
>> +    return EFI_OUT_OF_RESOURCES;
>> +  }
>> +
>> +  AcquireLockOnlyAtBootTime (&mMmCommunicationLock);
>> +
>> +  // Set up the MM communication.
>> +  BufferSize    = mMmCommunicationBufferSize;
>> +  CommHeader    = mMmCommunicationBuffer;
>> +  PolicyHeader  = (VAR_CHECK_POLICY_COMM_HEADER*)&CommHeader->Data;
>> +  PolicyBuffer  = (VOID*)(PolicyHeader + 1);
>> +  CopyGuid( &CommHeader->HeaderGuid, &gVarCheckPolicyLibMmiHandlerGuid );
>> +  CommHeader->MessageLength = BufferSize;
>> +  PolicyHeader->Signature   = VAR_CHECK_POLICY_COMM_SIG;
>> +  PolicyHeader->Revision    = VAR_CHECK_POLICY_COMM_REVISION;
>> +  PolicyHeader->Command     = VAR_CHECK_POLICY_COMMAND_REGISTER;
>> +
>> +  // Copy the policy into place. This copy is safe because we've already tested above.
>> +  CopyMem( PolicyBuffer, NewPolicy, NewPolicy->Size );
>> +
>> +  Status = InternalMmCommunicate (CommHeader, &BufferSize);
>> +  DEBUG(( DEBUG_VERBOSE, "%a - MmCommunication returned %r.\n", __FUNCTION__, Status ));
>> +
>> +  ReleaseLockOnlyAtBootTime (&mMmCommunicationLock);
>> +
>> +  return (EFI_ERROR( Status )) ? Status : PolicyHeader->Result;
>> +}
>> +
>> +
>> +/**
>> +  This helper function takes care of the overhead of formatting, sending, and interpreting
>> +  the results for a single DumpVariablePolicy request.
>> +
>> +  @param[in]      PageRequested   The page of the paginated results from MM. 0 for metadata.
>> +  @param[out]     TotalSize       The total size of the entire buffer. Returned as part of metadata.
>> +  @param[out]     PageSize        The size of the current page being returned. Not valid as part of metadata.
>> +  @param[out]     HasMore         A flag indicating whether there are more pages after this one.
>> +  @param[out]     Buffer          The start of the current page from MM.
>> +
>> +  @retval     EFI_SUCCESS             Output params have been updated (either metadata or dump page).
>> +  @retval     EFI_INVALID_PARAMETER   One of the output params is NULL.
>> +  @retval     Others                  Response from MM handler.
>> +
>> +**/
>> +STATIC
>> +EFI_STATUS
>> +DumpVariablePolicyHelper (
>> +  IN  UINT32        PageRequested,
>> +  OUT UINT32        *TotalSize,
>> +  OUT UINT32        *PageSize,
>> +  OUT BOOLEAN       *HasMore,
>> +  OUT UINT8         **Buffer
>> +  )
>> +{
>> +  EFI_STATUS                              Status;
>> +  EFI_MM_COMMUNICATE_HEADER               *CommHeader;
>> +  VAR_CHECK_POLICY_COMM_HEADER            *PolicyHeader;
>> +  VAR_CHECK_POLICY_COMM_DUMP_PARAMS       *CommandParams;
>> +  UINTN                                   BufferSize;
>> +
>> +  if (TotalSize == NULL || PageSize == NULL || HasMore == NULL || Buffer == NULL) {
>> +    return EFI_INVALID_PARAMETER;
>> +  }
>> +
>> +  // Set up the MM communication.
>> +  BufferSize    = mMmCommunicationBufferSize;
>> +  CommHeader    = mMmCommunicationBuffer;
>> +  PolicyHeader  = (VAR_CHECK_POLICY_COMM_HEADER*)&CommHeader->Data;
>> +  CommandParams = (VAR_CHECK_POLICY_COMM_DUMP_PARAMS*)(PolicyHeader + 1);
>> +  CopyGuid( &CommHeader->HeaderGuid, &gVarCheckPolicyLibMmiHandlerGuid );
>> +  CommHeader->MessageLength = BufferSize;
>> +  PolicyHeader->Signature   = VAR_CHECK_POLICY_COMM_SIG;
>> +  PolicyHeader->Revision    = VAR_CHECK_POLICY_COMM_REVISION;
>> +  PolicyHeader->Command     = VAR_CHECK_POLICY_COMMAND_DUMP;
>> +
>> +  CommandParams->PageRequested = PageRequested;
>> +
>> +  Status = InternalMmCommunicate (CommHeader, &BufferSize);
>> +  DEBUG(( DEBUG_VERBOSE, "%a - MmCommunication returned %r.\n", __FUNCTION__, Status ));
>> +
>> +  if (!EFI_ERROR( Status )) {
>> +    Status = PolicyHeader->Result;
>> +    *TotalSize = CommandParams->TotalSize;
>> +    *PageSize = CommandParams->PageSize;
>> +    *HasMore = CommandParams->HasMore;
>> +    *Buffer = (UINT8*)(CommandParams + 1);
>> +  }
>> +
>> +  return Status;
>> +}
>> +
>> +
>> +/**
>> +  This API function will dump the entire contents of the variable policy table.
>> +
>> +  Similar to GetVariable, the first call can be made with a 0 size and it will return
>> +  the size of the buffer required to hold the entire table.
>> +
>> +  @param[out]     Policy  Pointer to the policy buffer. Can be NULL if Size is 0.
>> +  @param[in,out]  Size    On input, the size of the output buffer. On output, the size
>> +                          of the data returned.
>> +
>> +  @retval     EFI_SUCCESS             Policy data is in the output buffer and Size has been updated.
>> +  @retval     EFI_INVALID_PARAMETER   Size is NULL, or Size is non-zero and Policy is NULL.
>> +  @retval     EFI_BUFFER_TOO_SMALL    Size is insufficient to hold policy. Size updated with required size.
>> +
>> +**/
>> +STATIC
>> +EFI_STATUS
>> +EFIAPI
>> +ProtocolDumpVariablePolicy (
>> +  OUT UINT8             *Policy OPTIONAL,
>> +  IN OUT UINT32         *Size
>> +  )
>> +{
>> +  EFI_STATUS    Status;
>> +  UINT8         *Source;
>> +  UINT8         *Destination;
>> +  UINT32        PolicySize;
>> +  UINT32        PageSize;
>> +  BOOLEAN       HasMore;
>> +  UINT32        PageIndex;
>> +
>> +  if (Size == NULL || (*Size > 0 && Policy == NULL)) {
>> +    return EFI_INVALID_PARAMETER;
>> +  }
>> +
>> +  AcquireLockOnlyAtBootTime (&mMmCommunicationLock);
>> +
>> +  // Repeat this whole process until we either have a failure case or get the entire buffer.
>> +  do {
>> +    // First, we must check the zero page to determine the buffer size and
>> +    // reset the internal state.
>> +    PolicySize = 0;
>> +    PageSize = 0;
>> +    HasMore = FALSE;
>> +    Status = DumpVariablePolicyHelper (0, &PolicySize, &PageSize, &HasMore, &Source);
>> +    if (EFI_ERROR (Status)) {
>> +      break;
>> +    }
>> +
>> +    // If we're good, we can at least check the required size now.
>> +    if (*Size < PolicySize) {
>> +      *Size = PolicySize;
>> +      Status = EFI_BUFFER_TOO_SMALL;
>> +      break;
>> +    }
>> +
>> +    // On further thought, let's update the size either way.
>> +    *Size = PolicySize;
>> +    // And get ready to ROCK.
>> +    Destination = Policy;
>> +
>> +    // Keep looping and copying until we're either done or freak out.
>> +    for (PageIndex = 1; !EFI_ERROR (Status) && HasMore && PageIndex < MAX_UINT32; PageIndex++) {
>> +      Status = DumpVariablePolicyHelper (PageIndex, &PolicySize, &PageSize, &HasMore, &Source);
>> +      if (!EFI_ERROR (Status)) {
>> +        CopyMem (Destination, Source, PageSize);
>> +        Destination += PageSize;
>> +      }
>> +    }
>> +
>> +    // Next, we check to see whether
>> +  } while (Status == EFI_TIMEOUT);
>> +
>> +  ReleaseLockOnlyAtBootTime (&mMmCommunicationLock);
>> +
>> +  // There's currently no use for this, but it shouldn't be hard to implement.
>> +  return Status;
>> +}
>> +
>> +
>> +/**
>> +  This API function locks the interface so that no more policy updates
>> +  can be performed or changes made to the enforcement until the next boot.
>> +
>> +  @retval     EFI_SUCCESS
>> +  @retval     Others        An error has prevented this command from completing.
>> +
>> +**/
>> +STATIC
>> +EFI_STATUS
>> +EFIAPI
>> +ProtocolLockVariablePolicy (
>> +  VOID
>> +  )
>> +{
>> +  EFI_STATUS                    Status;
>> +  EFI_MM_COMMUNICATE_HEADER     *CommHeader;
>> +  VAR_CHECK_POLICY_COMM_HEADER  *PolicyHeader;
>> +  UINTN                         BufferSize;
>> +
>> +  AcquireLockOnlyAtBootTime (&mMmCommunicationLock);
>> +
>> +  // Set up the MM communication.
>> +  BufferSize    = mMmCommunicationBufferSize;
>> +  CommHeader    = mMmCommunicationBuffer;
>> +  PolicyHeader  = (VAR_CHECK_POLICY_COMM_HEADER*)&CommHeader->Data;
>> +  CopyGuid( &CommHeader->HeaderGuid, &gVarCheckPolicyLibMmiHandlerGuid );
>> +  CommHeader->MessageLength = BufferSize;
>> +  PolicyHeader->Signature   = VAR_CHECK_POLICY_COMM_SIG;
>> +  PolicyHeader->Revision    = VAR_CHECK_POLICY_COMM_REVISION;
>> +  PolicyHeader->Command     = VAR_CHECK_POLICY_COMMAND_LOCK;
>> +
>> +  Status = InternalMmCommunicate (CommHeader, &BufferSize);
>> +  DEBUG(( DEBUG_VERBOSE, "%a - MmCommunication returned %r.\n", __FUNCTION__, Status ));
>> +
>> +  ReleaseLockOnlyAtBootTime (&mMmCommunicationLock);
>> +
>> +  return (EFI_ERROR( Status )) ? Status : PolicyHeader->Result;
>> +}
>> +
>> +
>> +/**
>> +  This helper function locates the shared comm buffer and assigns it to input pointers.
>> +
>> +  @param[in,out]  BufferSize      On input, the minimum buffer size required INCLUDING the MM communicate header.
>> +                                  On output, the size of the matching buffer found.
>> +  @param[out]     LocatedBuffer   A pointer to the matching buffer.
>> +
>> +  @retval     EFI_SUCCESS
>> +  @retval     EFI_INVALID_PARAMETER   One of the output pointers was NULL.
>> +  @retval     EFI_OUT_OF_RESOURCES    Not enough memory to allocate a comm buffer.
>> +
>> +**/
>> +STATIC
>> +EFI_STATUS
>> +InitMmCommonCommBuffer (
>> +  IN OUT  UINTN       *BufferSize,
>> +  OUT     VOID        **LocatedBuffer
>> +  )
>> +{
>> +  EFI_STATUS                  Status;
>> +
>> +  Status = EFI_SUCCESS;
>> +
>> +  // Make sure that we're working with good pointers.
>> +  if (BufferSize == NULL || LocatedBuffer == NULL) {
>> +    return EFI_INVALID_PARAMETER;
>> +  }
>> +
>> +  // Allocate the runtime memory for the comm buffer.
>> +  *LocatedBuffer = AllocateRuntimePool (*BufferSize);
>> +  if (*LocatedBuffer == NULL) {
>> +    Status = EFI_OUT_OF_RESOURCES;
>> +    *BufferSize = 0;
>> +  }
>> +
>> +  EfiInitializeLock (&mMmCommunicationLock, TPL_NOTIFY);
>> +
>> +  return Status;
>> +}
>> +
>> +
>> +/**
>> +  This helper is responsible for telemetry and any other actions that
>> +  need to be taken if the VariablePolicy fails to lock.
>> +
>> +  NOTE: It's possible that parts of this handling will need to become
>> +        part of a platform policy.
>> +
>> +  @param[in]  FailureStatus   The failure that was reported by LockVariablePolicy
>> +
>> +**/
>> +STATIC
>> +VOID
>> +VariablePolicyHandleFailureToLock (
>> +  IN  EFI_STATUS      FailureStatus
>> +  )
>> +{
>> +  // For now, there's no agreed-upon policy for this.
>> +  return;
>> +}
>> +
>> +
>> +/**
>> +  ReadyToBoot Callback
>> +  Lock the VariablePolicy interface if it hasn't already been locked.
>> +
>> +  @param[in]  Event     Event whose notification function is being invoked
>> +  @param[in]  Context   Pointer to the notification function's context
>> +
>> +**/
>> +STATIC
>> +VOID
>> +EFIAPI
>> +LockPolicyInterfaceAtReadyToBoot (
>> +  IN      EFI_EVENT                 Event,
>> +  IN      VOID                      *Context
>> +  )
>> +{
>> +  EFI_STATUS  Status;
>> +
>> +  Status = ProtocolLockVariablePolicy();
>> +
>> +  if (EFI_ERROR( Status )) {
>> +    VariablePolicyHandleFailureToLock( Status );
>> +  }
>> +  else {
>> +    gBS->CloseEvent( Event );
>> +  }
>> +
>> +}
>> +
>> +
>> +/**
>> +  Convert internal pointer addresses to virtual addresses.
>> +
>> +  @param[in] Event      Event whose notification function is being invoked.
>> +  @param[in] Context    The pointer to the notification function's context, which
>> +                        is implementation-dependent.
>> +**/
>> +STATIC
>> +VOID
>> +EFIAPI
>> +VariablePolicyVirtualAddressCallback (
>> +  IN  EFI_EVENT   Event,
>> +  IN  VOID        *Context
>> +  )
>> +{
>> +  EfiConvertPointer (0, (VOID **)&mMmCommunication);
>> +  EfiConvertPointer (0, (VOID **)&mMmCommunicationBuffer);
>> +}
>> +
>> +
>> +/**
>> +  The driver's entry point.
>> +
>> +  @param[in] ImageHandle  The firmware allocated handle for the EFI image.
>> +  @param[in] SystemTable  A pointer to the EFI System Table.
>> +
>> +  @retval EFI_SUCCESS     The entry point executed successfully.
>> +  @retval other           Some error occured when executing this entry point.
>> +
>> +**/
>> +EFI_STATUS
>> +EFIAPI
>> +VariablePolicySmmDxeMain (
>> +  IN    EFI_HANDLE                  ImageHandle,
>> +  IN    EFI_SYSTEM_TABLE            *SystemTable
>> +  )
>> +{
>> +  EFI_STATUS              Status;
>> +  BOOLEAN                 ProtocolInstalled;
>> +  BOOLEAN                 CallbackRegistered;
>> +  BOOLEAN                 VirtualAddressChangeRegistered;
>> +  EFI_EVENT               ReadyToBootEvent;
>> +  EFI_EVENT               VirtualAddressChangeEvent;
>> +
>> +  Status = EFI_SUCCESS;
>> +  ProtocolInstalled = FALSE;
>> +  CallbackRegistered = FALSE;
>> +  VirtualAddressChangeRegistered = FALSE;
>> +
>> +  // Update the minimum buffer size.
>> +  mMmCommunicationBufferSize = VAR_CHECK_POLICY_MM_COMM_BUFFER_SIZE;
>> +  // Locate the shared comm buffer to use for sending MM commands.
>> +  Status = InitMmCommonCommBuffer( &mMmCommunicationBufferSize, &mMmCommunicationBuffer );
>> +  if (EFI_ERROR( Status )) {
>> +    DEBUG((DEBUG_ERROR, "%a - Failed to locate a viable MM comm buffer! %r\n", __FUNCTION__, Status));
>> +    ASSERT_EFI_ERROR( Status );
>> +    return Status;
>> +  }
>> +
>> +  // Locate the MmCommunication protocol.
>> +  Status = gBS->LocateProtocol( &gEfiMmCommunication2ProtocolGuid, NULL, (VOID**)&mMmCommunication );
>> +  if (EFI_ERROR( Status )) {
>> +    DEBUG((DEBUG_ERROR, "%a - Failed to locate MmCommunication protocol! %r\n", __FUNCTION__, Status));
>> +    ASSERT_EFI_ERROR( Status );
>> +    return Status;
>> +  }
>> +
>> +  // Configure the VariablePolicy protocol structure.
>> +  mVariablePolicyProtocol.Revision                = EDKII_VARIABLE_POLICY_PROTOCOL_REVISION;
>> +  mVariablePolicyProtocol.DisableVariablePolicy   = ProtocolDisableVariablePolicy;
>> +  mVariablePolicyProtocol.IsVariablePolicyEnabled = ProtocolIsVariablePolicyEnabled;
>> +  mVariablePolicyProtocol.RegisterVariablePolicy  = ProtocolRegisterVariablePolicy;
> 
> (2) "error: assignment from incompatible pointer type [-Werror]"
> 
> Because, with my local modification for (1), the LHS now takes a
> pointer-to-CONST, but the RHS is declared (in the present patch) as
> 
>   STATIC
>   EFI_STATUS
>   EFIAPI
>   ProtocolRegisterVariablePolicy (
>     IN VARIABLE_POLICY_ENTRY    *NewPolicy
>     )
> 
> So I modified this too, to take a pointer-to-CONST. That allowed the
> builds to complete.
> 
> Therefore I suggest one of the following:
> 
> (a) If CONST is not important in the RegisterVariablePolicy() lib class
> API, then please remove CONST from there (and the implementation(s) of
> that function).
> 
> (b) Alternatively, if CONST is preferred in the library, then
> 
> (b1) please squash the following hunk:
> 
>> diff --git a/MdeModulePkg/Include/Protocol/VariablePolicy.h b/MdeModulePkg/Include/Protocol/VariablePolicy.h
>> index 30d6c155ae6a..83b6a999df07 100644
>> --- a/MdeModulePkg/Include/Protocol/VariablePolicy.h
>> +++ b/MdeModulePkg/Include/Protocol/VariablePolicy.h
>> @@ -102,7 +102,7 @@ EFI_STATUS
>>  typedef
>>  EFI_STATUS
>>  (EFIAPI *REGISTER_VARIABLE_POLICY)(
>> -  IN VARIABLE_POLICY_ENTRY *PolicyEntry
>> +  IN CONST VARIABLE_POLICY_ENTRY *PolicyEntry
>>    );
>>
>>  /**
> 
> into patch "MdeModulePkg: Define the VariablePolicy protocol interface".
> 
> (b2) And please squash the following hunk:
> 
>> diff --git a/MdeModulePkg/Universal/Variable/RuntimeDxe/VariablePolicySmmDxe.c b/MdeModulePkg/Universal/Variable/RuntimeDxe/VariablePolicySmmDxe.c
>> index 3d799025983a..e2d4cf4cec1a 100644
>> --- a/MdeModulePkg/Universal/Variable/RuntimeDxe/VariablePolicySmmDxe.c
>> +++ b/MdeModulePkg/Universal/Variable/RuntimeDxe/VariablePolicySmmDxe.c
>> @@ -176,7 +176,7 @@ STATIC
>>  EFI_STATUS
>>  EFIAPI
>>  ProtocolRegisterVariablePolicy (
>> -  IN VARIABLE_POLICY_ENTRY    *NewPolicy
>> +  IN CONST VARIABLE_POLICY_ENTRY    *NewPolicy
>>    )
>>  {
>>    EFI_STATUS                                Status;
> 
> into the present patch.
> 
> I've used (b1)+(b2) locally, and those together allow the builds to
> complete.
> 
> 
> Now, I wonder why the GCC / OVMF build(s) in the github.com CI did not
> report this problem. According to the C99 standard, "6.7.5.3 Function
> declarators (including prototypes)", paragraph 15:
> 
>   For two function types to be compatible, both shall specify compatible
>   return types. [...]  Moreover, the parameter type lists, if both are
>   present, shall agree in the number of parameters and in use of the
>   ellipsis terminator; corresponding parameters shall have compatible
>   types. [...]
> 
> Furthermore, from "6.7.5.1 Pointer declarators", paragraph 2:
> 
>   For two pointer types to be compatible, both shall be identically
>   qualified and both shall be pointers to compatible types.
> 
> Yet further, from "6.5.16.1 Simple assignment", paragraph 1:
> 
>   One of the following shall hold:
> 
>   [...]
> 
>   - both operands are pointers to qualified or unqualified versions of
>     compatible types, and the type pointed to by the left has all the
>     qualifiers of the type pointed to by the right;
> 
>   [...]
> 
> So the thought process is:
> 
> - "mVariablePolicyProtocol.RegisterVariablePolicy" has type
> 
>     EFI_STATUS (EFIAPI *)(      VARIABLE_POLICY_ENTRY *)
> 
>   while a pointer to RegisterVariablePolicy(), from the library, has
>   type
> 
>     EFI_STATUS (EFIAPI *)(const VARIABLE_POLICY_ENTRY *)
> 
>   For the assignment, these need to be compatible, per 6.5.16.1p1.
> 
>   Are they compatible?
> 
> - Per 6.7.5.1p2, that depends on whether the pointed-to function types
>   are compatible.
> 
>   Are the pointed-to function types compatible?
> 
> - Per 6.7.5.3p15, that depends on whether (VARIABLE_POLICY_ENTRY *) and
>   (const VARIABLE_POLICY_ENTRY *) are compatible.
> 
>   Are those pointer types compatible?
> 
> - They're not, based on 6.7.5.1p2 -- they are not identically qualified.
> 
> So IMO (according to the language standard), the code should have been
> flagged by MSVC too; but more importantly, I don't understand why the
> GCC5 / Ubuntu builds succeeded in CI.
> 
> Thanks!
> Laszlo
> 
> 
>> +  mVariablePolicyProtocol.DumpVariablePolicy      = ProtocolDumpVariablePolicy;
>> +  mVariablePolicyProtocol.LockVariablePolicy      = ProtocolLockVariablePolicy;
>> +
>> +  // Register all the protocols and return the status.
>> +  Status = gBS->InstallMultipleProtocolInterfaces( &ImageHandle,
>> +                                                   &gEdkiiVariablePolicyProtocolGuid, &mVariablePolicyProtocol,
>> +                                                   NULL );
>> +  if (EFI_ERROR( Status )) {
>> +    DEBUG(( DEBUG_ERROR, "%a - Failed to install protocol! %r\n", __FUNCTION__, Status ));
>> +    goto Exit;
>> +  }
>> +  else {
>> +    ProtocolInstalled = TRUE;
>> +  }
>> +
>> +  //
>> +  // Register a callback for ReadyToBoot so that the interface is at least locked before
>> +  // dispatching any bootloaders or UEFI apps.
>> +  Status = gBS->CreateEventEx( EVT_NOTIFY_SIGNAL,
>> +                               TPL_CALLBACK,
>> +                               LockPolicyInterfaceAtReadyToBoot,
>> +                               NULL,
>> +                               &gEfiEventReadyToBootGuid,
>> +                               &ReadyToBootEvent );
>> +  if (EFI_ERROR( Status )) {
>> +    DEBUG(( DEBUG_ERROR, "%a - Failed to create ReadyToBoot event! %r\n", __FUNCTION__, Status ));
>> +    goto Exit;
>> +  }
>> +  else {
>> +    CallbackRegistered = TRUE;
>> +  }
>> +
>> +  //
>> +  // Register a VirtualAddressChange callback for the MmComm protocol and Comm buffer.
>> +  Status = gBS->CreateEventEx (EVT_NOTIFY_SIGNAL,
>> +                                TPL_NOTIFY,
>> +                                VariablePolicyVirtualAddressCallback,
>> +                                NULL,
>> +                                &gEfiEventVirtualAddressChangeGuid,
>> +                                &VirtualAddressChangeEvent);
>> +  if (EFI_ERROR( Status )) {
>> +    DEBUG(( DEBUG_ERROR, "%a - Failed to create VirtualAddressChange event! %r\n", __FUNCTION__, Status ));
>> +    goto Exit;
>> +  }
>> +  else {
>> +    VirtualAddressChangeRegistered = TRUE;
>> +  }
>> +
>> +
>> +Exit:
>> +  //
>> +  // If we're about to return a failed status (and unload this driver), we must first undo anything that
>> +  // has been successfully done.
>> +  if (EFI_ERROR( Status )) {
>> +    if (ProtocolInstalled) {
>> +      gBS->UninstallProtocolInterface( &ImageHandle, &gEdkiiVariablePolicyProtocolGuid, &mVariablePolicyProtocol );
>> +    }
>> +    if (CallbackRegistered) {
>> +      gBS->CloseEvent( ReadyToBootEvent );
>> +    }
>> +    if (VirtualAddressChangeRegistered) {
>> +      gBS->CloseEvent( VirtualAddressChangeEvent );
>> +    }
>> +  }
>> +
>> +  return Status;
>> +}
>> diff --git a/MdeModulePkg/Universal/Variable/RuntimeDxe/VariableSmmRuntimeDxe.c b/MdeModulePkg/Universal/Variable/RuntimeDxe/VariableSmmRuntimeDxe.c
>> index 663a1aaa128f..c47e614d81f4 100644
>> --- a/MdeModulePkg/Universal/Variable/RuntimeDxe/VariableSmmRuntimeDxe.c
>> +++ b/MdeModulePkg/Universal/Variable/RuntimeDxe/VariableSmmRuntimeDxe.c
>> @@ -65,6 +65,17 @@ EFI_LOCK                         mVariableServicesLock;
>>  EDKII_VARIABLE_LOCK_PROTOCOL     mVariableLock;
>>  EDKII_VAR_CHECK_PROTOCOL         mVarCheck;
>>
>> +/**
>> +  The logic to initialize the VariablePolicy engine is in its own file.
>> +
>> +**/
>> +EFI_STATUS
>> +EFIAPI
>> +VariablePolicySmmDxeMain (
>> +  IN    EFI_HANDLE                  ImageHandle,
>> +  IN    EFI_SYSTEM_TABLE            *SystemTable
>> +  );
>> +
>>  /**
>>    Some Secure Boot Policy Variable may update following other variable changes(SecureBoot follows PK change, etc).
>>    Record their initial State when variable write service is ready.
>> @@ -1796,6 +1807,9 @@ VariableSmmRuntimeInitialize (
>>           &mVirtualAddressChangeEvent
>>           );
>>
>> +  // Initialize the VariablePolicy protocol and engine.
>> +  VariablePolicySmmDxeMain (ImageHandle, SystemTable);
>> +
>>    return EFI_SUCCESS;
>>  }
>>
>> diff --git a/MdeModulePkg/Universal/Variable/RuntimeDxe/VariableRuntimeDxe.inf b/MdeModulePkg/Universal/Variable/RuntimeDxe/VariableRuntimeDxe.inf
>> index ceea5d1ff9ac..48ac167906f7 100644
>> --- a/MdeModulePkg/Universal/Variable/RuntimeDxe/VariableRuntimeDxe.inf
>> +++ b/MdeModulePkg/Universal/Variable/RuntimeDxe/VariableRuntimeDxe.inf
>> @@ -10,6 +10,7 @@
>>  #  buffer overflow or integer overflow.
>>  #
>>  # Copyright (c) 2006 - 2019, Intel Corporation. All rights reserved.<BR>
>> +# Copyright (c) Microsoft Corporation.
>>  # SPDX-License-Identifier: BSD-2-Clause-Patent
>>  #
>>  ##
>> @@ -69,6 +70,7 @@ [LibraryClasses]
>>    TpmMeasurementLib
>>    AuthVariableLib
>>    VarCheckLib
>> +  VariablePolicyLib
>>
>>  [Protocols]
>>    gEfiFirmwareVolumeBlockProtocolGuid           ## CONSUMES
>> diff --git a/MdeModulePkg/Universal/Variable/RuntimeDxe/VariableSmm.inf b/MdeModulePkg/Universal/Variable/RuntimeDxe/VariableSmm.inf
>> index bc3033588d40..bbc8d2080193 100644
>> --- a/MdeModulePkg/Universal/Variable/RuntimeDxe/VariableSmm.inf
>> +++ b/MdeModulePkg/Universal/Variable/RuntimeDxe/VariableSmm.inf
>> @@ -19,6 +19,7 @@
>>  #  the authentication service provided in this driver will be broken, and the behavior is undefined.
>>  #
>>  # Copyright (c) 2010 - 2019, Intel Corporation. All rights reserved.<BR>
>> +# Copyright (c) Microsoft Corporation.
>>  # SPDX-License-Identifier: BSD-2-Clause-Patent
>>  #
>>  ##
>> @@ -78,6 +79,8 @@ [LibraryClasses]
>>    AuthVariableLib
>>    VarCheckLib
>>    UefiBootServicesTableLib
>> +  VariablePolicyLib
>> +  VariablePolicyHelperLib
>>
>>  [Protocols]
>>    gEfiSmmFirmwareVolumeBlockProtocolGuid        ## CONSUMES
>> diff --git a/MdeModulePkg/Universal/Variable/RuntimeDxe/VariableSmmRuntimeDxe.inf b/MdeModulePkg/Universal/Variable/RuntimeDxe/VariableSmmRuntimeDxe.inf
>> index 01564e4c5068..f217530b2985 100644
>> --- a/MdeModulePkg/Universal/Variable/RuntimeDxe/VariableSmmRuntimeDxe.inf
>> +++ b/MdeModulePkg/Universal/Variable/RuntimeDxe/VariableSmmRuntimeDxe.inf
>> @@ -14,6 +14,7 @@
>>  #  the authentication service provided in this driver will be broken, and the behavior is undefined.
>>  #
>>  # Copyright (c) 2010 - 2019, Intel Corporation. All rights reserved.<BR>
>> +# Copyright (c) Microsoft Corporation.<BR>
>>  # SPDX-License-Identifier: BSD-2-Clause-Patent
>>  #
>>  ##
>> @@ -42,6 +43,7 @@ [Sources]
>>    VariableParsing.c
>>    VariableParsing.h
>>    Variable.h
>> +  VariablePolicySmmDxe.c
>>
>>  [Packages]
>>    MdePkg/MdePkg.dec
>> @@ -56,6 +58,8 @@ [LibraryClasses]
>>    DxeServicesTableLib
>>    UefiDriverEntryPoint
>>    TpmMeasurementLib
>> +  SafeIntLib
>> +  PcdLib
>>
>>  [Protocols]
>>    gEfiVariableWriteArchProtocolGuid             ## PRODUCES
>> @@ -67,11 +71,15 @@ [Protocols]
>>    gEfiSmmVariableProtocolGuid
>>    gEdkiiVariableLockProtocolGuid                ## PRODUCES
>>    gEdkiiVarCheckProtocolGuid                    ## PRODUCES
>> +  gEdkiiVariablePolicyProtocolGuid              ## PRODUCES
>>
>>  [FeaturePcd]
>>    gEfiMdeModulePkgTokenSpaceGuid.PcdEnableVariableRuntimeCache           ## CONSUMES
>>    gEfiMdeModulePkgTokenSpaceGuid.PcdVariableCollectStatistics            ## CONSUMES
>>
>> +[Pcd]
>> +  gEfiMdeModulePkgTokenSpaceGuid.PcdAllowVariablePolicyEnforcementDisable     ## CONSUMES
>> +
>>  [Guids]
>>    ## PRODUCES             ## GUID # Signature of Variable store header
>>    ## CONSUMES             ## GUID # Signature of Variable store header
>> @@ -99,6 +107,8 @@ [Guids]
>>    ## SOMETIMES_CONSUMES   ## Variable:L"dbt"
>>    gEfiImageSecurityDatabaseGuid
>>
>> +  gVarCheckPolicyLibMmiHandlerGuid
>> +
>>  [Depex]
>>    gEfiMmCommunication2ProtocolGuid
>>
>>
> 
> 
> 
> 
>