Re: [edk2-platforms:PATCH] Intel/IntelSiliconPkg Implement SmmAccess in IntelSiliconPkg

["Marc W Chen" <marc.w.chen@intel.com>]

Thanks Ray and Sai for reviewing, please see my below reply for your questions.

1. The reason why I put the Library folder in Feature/SmmAccess folder is because I saw Feature/Capsule also doing it this way, so I thought we want to put all related implementation in the same feature folder including library, please let me know if you want me to move the PeiSmmAccessLib to root Library folder.

2. I saw that Vtd also depend on MdeModulePkg, so I thought IntelSiliconPkg is allowed to use MdeModulePkg, and SmmAccess code need SmmAccess.h, which is in MdeModulePkg, even we can change to use MmAccess.h from MdePkg now, but I thought the SMM is belong to x86 silicon, so use SmmAccess.h is better than MmAccess.h, let me know if you prefer to use MmAccess, then I'll modify the Patch to use that.

Thanks,
Marc

> -----Original Message-----
> From: Ni, Ray
> Sent: Saturday, August 24, 2019 5:03 AM
> To: Chaganty, Rangasai V <rangasai.v.chaganty@intel.com>; Chen, Marc W
> <marc.w.chen@intel.com>; devel@edk2.groups.io
> Subject: RE: [edk2-platforms:PATCH] Intel/IntelSiliconPkg Implement
> SmmAccess in IntelSiliconPkg
> 
> It's not recommended to make IntelSiliconPkg depend on MdeModulePkg.
> 
> > -----Original Message-----
> > From: Chaganty, Rangasai V
> > Sent: Friday, August 23, 2019 11:34 AM
> > To: Chen, Marc W <marc.w.chen@intel.com>; devel@edk2.groups.io
> > Cc: Ni, Ray <ray.ni@intel.com>
> > Subject: RE: [edk2-platforms:PATCH] Intel/IntelSiliconPkg Implement
> SmmAccess in IntelSiliconPkg
> >
> > May I know the reason to implement the SmmAccessLib instance under
> \Feature folder?
> > Can we move it under IntelSiliconPkg\Library (We need to create a library
> folder in the root) and keep just the module in the
> > \Feature folder?
> >
> > I've noticed there is a dependency on MdeModulePkg with this change.
> > Could you provide the reason to have such dependency as part of this
> change?
> >
> > Thanks,
> > Sai
> >
> > -----Original Message-----
> > From: Chen, Marc W
> > Sent: Friday, August 23, 2019 3:28 AM
> > To: devel@edk2.groups.io
> > Cc: Chen, Marc W <marc.w.chen@intel.com>; Ni, Ray <ray.ni@intel.com>;
> Chaganty, Rangasai V
> > <rangasai.v.chaganty@intel.com>
> > Subject: [edk2-platforms:PATCH] Intel/IntelSiliconPkg Implement
> SmmAccess in IntelSiliconPkg
> >
> > REF:https://bugzilla.tianocore.org/show_bug.cgi?id=2121
> >
> > Implement SmmAccess for PEI and DXE phase in IntelSiliconPkg
> >
> > Signed-off-by: Marc Chen <marc.w.chen@intel.com>
> > Cc: Ray Ni <ray.ni@intel.com>
> > Cc: Rangasai V Chaganty <rangasai.v.chaganty@intel.com>
> > ---
> >  .../Library/PeiSmmAccessLib/PeiSmmAccessLib.c      | 343
> +++++++++++++++++++++
> >  .../Library/PeiSmmAccessLib/PeiSmmAccessLib.inf    |  42 +++
> >  .../Feature/SmmAccess/SmmAccessDxe/SmmAccess.inf   |  47 +++
> >  .../SmmAccess/SmmAccessDxe/SmmAccessDriver.c       | 267
> ++++++++++++++++
> >  .../SmmAccess/SmmAccessDxe/SmmAccessDriver.h       | 160 ++++++++++
> >  .../IntelSiliconPkg/Include/Library/SmmAccessLib.h |  32 ++
> >  6 files changed, 891 insertions(+)
> >  create mode 100644
> Silicon/Intel/IntelSiliconPkg/Feature/SmmAccess/Library/PeiSmmAccessLib/
> PeiSmmAccessLib.c
> >  create mode 100644
> Silicon/Intel/IntelSiliconPkg/Feature/SmmAccess/Library/PeiSmmAccessLib/
> PeiSmmAccessLib.inf
> >  create mode 100644
> Silicon/Intel/IntelSiliconPkg/Feature/SmmAccess/SmmAccessDxe/SmmAcce
> ss.inf
> >  create mode 100644
> Silicon/Intel/IntelSiliconPkg/Feature/SmmAccess/SmmAccessDxe/SmmAcce
> ssDriver.c
> >  create mode 100644
> Silicon/Intel/IntelSiliconPkg/Feature/SmmAccess/SmmAccessDxe/SmmAcce
> ssDriver.h
> >  create mode 100644
> Silicon/Intel/IntelSiliconPkg/Include/Library/SmmAccessLib.h
> >
> > diff --git
> a/Silicon/Intel/IntelSiliconPkg/Feature/SmmAccess/Library/PeiSmmAccessLi
> b/PeiSmmAccessLib.c
> >
> b/Silicon/Intel/IntelSiliconPkg/Feature/SmmAccess/Library/PeiSmmAccessLi
> b/PeiSmmAccessLib.c
> > new file mode 100644
> > index 0000000000..88eb217d2a
> > --- /dev/null
> > +++
> b/Silicon/Intel/IntelSiliconPkg/Feature/SmmAccess/Library/PeiSmmAcce
> > +++ ssLib/PeiSmmAccessLib.c
> > @@ -0,0 +1,343 @@
> > +/** @file
> > +  This is to publish the SMM Access Ppi instance.
> > +
> > +  Copyright (c) 2019, Intel Corporation. All rights reserved.<BR>
> > +  SPDX-License-Identifier: BSD-2-Clause-Patent
> > +
> > +**/
> > +#include <Library/BaseMemoryLib.h>
> > +#include <Library/DebugLib.h>
> > +#include <Library/MemoryAllocationLib.h> #include
> > +<Library/PciSegmentLib.h> #include <Library/PeiServicesLib.h> #include
> > +<Library/HobLib.h> #include <Uefi/UefiBaseType.h> #include
> > +<Guid/SmramMemoryReserve.h>
> > +
> > +#include <Ppi/SmmAccess.h>
> > +#include <IndustryStandard/Pci22.h>
> > +
> > +#define SMM_ACCESS_PRIVATE_DATA_SIGNATURE SIGNATURE_32 ('4',
> '5', 's',
> > +'a')
> > +
> > +///
> > +/// Private data
> > +///
> > +typedef struct {
> > +  UINTN                 Signature;
> > +  EFI_HANDLE            Handle;
> > +  PEI_SMM_ACCESS_PPI    SmmAccess;
> > +  //
> > +  // Local Data for SMM Access interface goes here
> > +  //
> > +  UINTN                 NumberRegions;
> > +  EFI_SMRAM_DESCRIPTOR  *SmramDesc;
> > +} SMM_ACCESS_PRIVATE_DATA;
> > +
> > +#define SMM_ACCESS_PRIVATE_DATA_FROM_THIS(a) \
> > +        CR (a, \
> > +          SMM_ACCESS_PRIVATE_DATA, \
> > +          SmmAccess, \
> > +          SMM_ACCESS_PRIVATE_DATA_SIGNATURE \
> > +      )
> > +
> > +/**
> > +  This routine accepts a request to "open" a region of SMRAM.  The
> > +  region could be legacy ABSEG, HSEG, or TSEG near top of physical
> memory.
> > +  The use of "open" means that the memory is visible from all PEIM
> > +  and SMM agents.
> > +
> > +  @param[in] This             -  Pointer to the SMM Access Interface.
> > +  @param[in] DescriptorIndex  -  Region of SMRAM to Open.
> > +  @param[in] PeiServices      -  General purpose services available to every
> PEIM.
> > +
> > +  @retval EFI_SUCCESS            -  The region was successfully opened.
> > +  @retval EFI_DEVICE_ERROR       -  The region could not be opened
> because locked by
> > +                                    chipset.
> > +  @retval EFI_INVALID_PARAMETER  -  The descriptor index was out of
> bounds.
> > +**/
> > +EFI_STATUS
> > +EFIAPI
> > +Open (
> > +  IN EFI_PEI_SERVICES           **PeiServices,
> > +  IN PEI_SMM_ACCESS_PPI         *This,
> > +  IN UINTN                      DescriptorIndex
> > +  )
> > +{
> > +  SMM_ACCESS_PRIVATE_DATA *SmmAccess;
> > +
> > +  SmmAccess = SMM_ACCESS_PRIVATE_DATA_FROM_THIS (This);  if
> > + (DescriptorIndex >= SmmAccess->NumberRegions) {
> > +    DEBUG ((DEBUG_WARN, "SMRAM region out of range\n"));
> > +
> > +    return EFI_INVALID_PARAMETER;
> > +  } else if (SmmAccess->SmramDesc[DescriptorIndex].RegionState &
> EFI_SMRAM_LOCKED) {
> > +    //
> > +    // Cannot open a "locked" region
> > +    //
> > +    DEBUG ((DEBUG_WARN, "Cannot open a locked SMRAM region\n"));
> > +
> > +    return EFI_DEVICE_ERROR;
> > +  }
> > +
> > +  SmmAccess->SmramDesc[DescriptorIndex].RegionState &= (UINT64)
> > +~(EFI_SMRAM_CLOSED | EFI_ALLOCATED);
> > +  SmmAccess->SmramDesc[DescriptorIndex].RegionState |= (UINT64)
> > +EFI_SMRAM_OPEN;
> > +  SmmAccess->SmmAccess.OpenState = TRUE;
> > +  return EFI_SUCCESS;
> > +}
> > +
> > +/**
> > +  This routine accepts a request to "close" a region of SMRAM.  This is
> > +valid for
> > +  compatible SMRAM region.
> > +
> > +  @param[in] PeiServices      -  General purpose services available to every
> PEIM.
> > +  @param[in] This             -  Pointer to the SMM Access Interface.
> > +  @param[in] DescriptorIndex  -  Region of SMRAM to Close.
> > +
> > +  @retval EFI_SUCCESS            -  The region was successfully closed.
> > +  @retval EFI_DEVICE_ERROR       -  The region could not be closed because
> locked by
> > +                                    chipset.
> > +  @retval EFI_INVALID_PARAMETER  -  The descriptor index was out of
> bounds.
> > +**/
> > +EFI_STATUS
> > +EFIAPI
> > +Close (
> > +  IN EFI_PEI_SERVICES        **PeiServices,
> > +  IN PEI_SMM_ACCESS_PPI      *This,
> > +  IN UINTN                   DescriptorIndex
> > +  )
> > +{
> > +  SMM_ACCESS_PRIVATE_DATA *SmmAccess;
> > +  BOOLEAN                 OpenState;
> > +  UINT8                   Index;
> > +
> > +  SmmAccess = SMM_ACCESS_PRIVATE_DATA_FROM_THIS (This);  if
> > + (DescriptorIndex >= SmmAccess->NumberRegions) {
> > +    DEBUG ((DEBUG_WARN, "SMRAM region out of range\n"));
> > +
> > +    return EFI_INVALID_PARAMETER;
> > +  } else if (SmmAccess->SmramDesc[DescriptorIndex].RegionState &
> EFI_SMRAM_LOCKED) {
> > +    //
> > +    // Cannot close a "locked" region
> > +    //
> > +    DEBUG ((DEBUG_WARN, "Cannot close a locked SMRAM region\n"));
> > +
> > +    return EFI_DEVICE_ERROR;
> > +  }
> > +
> > +  if (SmmAccess->SmramDesc[DescriptorIndex].RegionState &
> EFI_SMRAM_CLOSED) {
> > +    return EFI_DEVICE_ERROR;
> > +  }
> > +
> > +  SmmAccess->SmramDesc[DescriptorIndex].RegionState &= (UINT64)
> > + ~EFI_SMRAM_OPEN;  SmmAccess-
> >SmramDesc[DescriptorIndex].RegionState |=
> > + (UINT64) (EFI_SMRAM_CLOSED | EFI_ALLOCATED);
> > +
> > +  //
> > +  // Find out if any regions are still open  //  OpenState = FALSE;
> > + for (Index = 0; Index < SmmAccess->NumberRegions; Index++) {
> > +    if ((SmmAccess->SmramDesc[Index].RegionState & EFI_SMRAM_OPEN)
> == EFI_SMRAM_OPEN) {
> > +      OpenState = TRUE;
> > +    }
> > +  }
> > +
> > +  SmmAccess->SmmAccess.OpenState = OpenState;
> > +  return EFI_SUCCESS;
> > +}
> > +
> > +/**
> > +  This routine accepts a request to "lock" SMRAM.  The
> > +  region could be legacy AB or TSEG near top of physical memory.
> > +  The use of "lock" means that the memory can no longer be opened
> > +  to PEIM.
> > +
> > +  @param[in] PeiServices      - General purpose services available to every
> PEIM.
> > +  @param[in] This             -  Pointer to the SMM Access Interface.
> > +  @param[in] DescriptorIndex  -  Region of SMRAM to Lock.
> > +
> > +  @retval EFI_SUCCESS            -  The region was successfully locked.
> > +  @retval EFI_DEVICE_ERROR       -  The region could not be locked because
> at least
> > +                                    one range is still open.
> > +  @retval EFI_INVALID_PARAMETER  -  The descriptor index was out of
> bounds.
> > +**/
> > +EFI_STATUS
> > +EFIAPI
> > +Lock (
> > +  IN EFI_PEI_SERVICES          **PeiServices,
> > +  IN PEI_SMM_ACCESS_PPI        *This,
> > +  IN UINTN                     DescriptorIndex
> > +  )
> > +{
> > +  SMM_ACCESS_PRIVATE_DATA *SmmAccess;
> > +
> > +  SmmAccess = SMM_ACCESS_PRIVATE_DATA_FROM_THIS (This);  if
> > + (DescriptorIndex >= SmmAccess->NumberRegions) {
> > +    DEBUG ((DEBUG_WARN, "SMRAM region out of range\n"));
> > +
> > +    return EFI_INVALID_PARAMETER;
> > +  } else if (SmmAccess->SmmAccess.OpenState) {
> > +    DEBUG ((DEBUG_WARN, "Cannot lock SMRAM when SMRAM regions
> are still
> > + open\n"));
> > +
> > +    return EFI_DEVICE_ERROR;
> > +  }
> > +
> > +  SmmAccess->SmramDesc[DescriptorIndex].RegionState |= (UINT64)
> > + EFI_SMRAM_LOCKED;  SmmAccess->SmmAccess.LockState = TRUE;
> > +
> > +  return EFI_SUCCESS;
> > +}
> > +
> > +/**
> > +  This routine services a user request to discover the SMRAM
> > +  capabilities of this platform.  This will report the possible
> > +  ranges that are possible for SMRAM access, based upon the
> > +  memory controller capabilities.
> > +
> > +  @param[in] PeiServices   - General purpose services available to every
> PEIM.
> > +  @param[in] This          -  Pointer to the SMRAM Access Interface.
> > +  @param[in] SmramMapSize  -  Pointer to the variable containing size of
> the
> > +                              buffer to contain the description information.
> > +  @param[in] SmramMap      -  Buffer containing the data describing the
> Smram
> > +                              region descriptors.
> > +
> > +  @retval EFI_BUFFER_TOO_SMALL  -  The user did not provide a sufficient
> buffer.
> > +  @retval EFI_SUCCESS           -  The user provided a sufficiently-sized buffer.
> > +**/
> > +EFI_STATUS
> > +EFIAPI
> > +GetCapabilities (
> > +  IN EFI_PEI_SERVICES                **PeiServices,
> > +  IN PEI_SMM_ACCESS_PPI              *This,
> > +  IN OUT UINTN                       *SmramMapSize,
> > +  IN OUT EFI_SMRAM_DESCRIPTOR        *SmramMap
> > +  )
> > +{
> > +  EFI_STATUS              Status;
> > +  SMM_ACCESS_PRIVATE_DATA *SmmAccess;
> > +  UINTN                   NecessaryBufferSize;
> > +
> > +  SmmAccess           = SMM_ACCESS_PRIVATE_DATA_FROM_THIS (This);
> > +  NecessaryBufferSize = SmmAccess->NumberRegions * sizeof
> > + (EFI_SMRAM_DESCRIPTOR);  if (*SmramMapSize < NecessaryBufferSize)
> {
> > +    DEBUG ((DEBUG_WARN, "SMRAM Map Buffer too small\n"));
> > +
> > +    Status = EFI_BUFFER_TOO_SMALL;
> > +  } else {
> > +    CopyMem (SmramMap, SmmAccess->SmramDesc,
> NecessaryBufferSize);
> > +    Status = EFI_SUCCESS;
> > +  }
> > +
> > +  *SmramMapSize = NecessaryBufferSize;
> > +  return Status;
> > +}
> > +
> > +/**
> > +  This function is to install an SMM Access PPI
> > +  - <b>Introduction</b> \n
> > +    A module to install a PPI for controlling SMM mode memory access
> basically for S3 resume usage.
> > +
> > +  - @pre
> > +    - _PEI_MASTER_BOOT_MODE_PEIM_PPI: A PPI published by
> foundation to get bootmode executed earlier.
> > +    - _PEI_PERMANENT_MEMORY_INSTALLED_PPI: a PPI that will be
> installed after memory controller initialization completed
> > to indicate that physical memory is usable after this point.
> > +
> > +  - @result
> > +    Publish _PEI_SMM_ACCESS_PPI.
> > +
> > +    @retval EFI_SUCCESS           - Ppi successfully started and installed.
> > +    @retval EFI_NOT_FOUND         - Ppi can't be found.
> > +    @retval EFI_OUT_OF_RESOURCES  - Ppi does not have enough
> resources to initialize the driver.
> > +**/
> > +EFI_STATUS
> > +EFIAPI
> > +PeiInstallSmmAccessPpi (
> > +  VOID
> > +  )
> > +{
> > +  EFI_STATUS                      Status;
> > +  UINTN                           Index;
> > +  EFI_PEI_PPI_DESCRIPTOR          *PpiList;
> > +  EFI_SMRAM_HOB_DESCRIPTOR_BLOCK  *DescriptorBlock;
> > +  SMM_ACCESS_PRIVATE_DATA         *SmmAccessPrivate;
> > +  VOID                            *HobList;
> > +  EFI_BOOT_MODE                   BootMode;
> > +
> > +  Status = PeiServicesGetBootMode (&BootMode);  if (EFI_ERROR (Status))
> > + {
> > +    //
> > +    // If not in S3 boot path. do nothing
> > +    //
> > +    return EFI_SUCCESS;
> > +  }
> > +
> > +  if (BootMode != BOOT_ON_S3_RESUME) {
> > +    return EFI_SUCCESS;
> > +  }
> > +  //
> > +  // Initialize private data
> > +  //
> > +  SmmAccessPrivate  = AllocateZeroPool (sizeof (*SmmAccessPrivate));
> > + ASSERT (SmmAccessPrivate != NULL);  if (SmmAccessPrivate == NULL) {
> > +    return EFI_OUT_OF_RESOURCES;
> > +  }
> > +  PpiList           = AllocateZeroPool (sizeof (*PpiList));
> > +  ASSERT (PpiList != NULL);
> > +  if (PpiList == NULL) {
> > +    return EFI_OUT_OF_RESOURCES;
> > +  }
> > +
> > +  SmmAccessPrivate->Signature =
> SMM_ACCESS_PRIVATE_DATA_SIGNATURE;
> > +  SmmAccessPrivate->Handle    = NULL;
> > +
> > +  //
> > +  // Get Hob list
> > +  //
> > +  HobList = GetFirstGuidHob (&gEfiSmmSmramMemoryGuid);  if (HobList
> ==
> > + NULL) {
> > +    DEBUG ((DEBUG_WARN, "SmramMemoryReserve HOB not found\n"));
> > +    return EFI_NOT_FOUND;
> > +  }
> > +
> > +  DescriptorBlock = (EFI_SMRAM_HOB_DESCRIPTOR_BLOCK *) ((UINT8 *)
> > + HobList + sizeof (EFI_HOB_GUID_TYPE));
> > +
> > +  //
> > +  // Alloc space for SmmAccessPrivate->SmramDesc  //
> > + SmmAccessPrivate->SmramDesc = AllocateZeroPool
> > + ((DescriptorBlock->NumberOfSmmReservedRegions) * sizeof
> (EFI_SMRAM_DESCRIPTOR));  if (SmmAccessPrivate->SmramDesc
> > == NULL) {
> > +    DEBUG ((DEBUG_WARN, "Alloc SmmAccessPrivate->SmramDesc
> fail.\n"));
> > +    return EFI_OUT_OF_RESOURCES;
> > +  }
> > +
> > +  DEBUG ((DEBUG_INFO, "Alloc SmmAccessPrivate->SmramDesc
> success.\n"));
> > +
> > +  //
> > +  // use the hob to publish SMRAM capabilities  //  for (Index = 0;
> > + Index < DescriptorBlock->NumberOfSmmReservedRegions; Index++) {
> > +    SmmAccessPrivate->SmramDesc[Index].PhysicalStart  =
> DescriptorBlock->Descriptor[Index].PhysicalStart;
> > +    SmmAccessPrivate->SmramDesc[Index].CpuStart       = DescriptorBlock-
> >Descriptor[Index].CpuStart;
> > +    SmmAccessPrivate->SmramDesc[Index].PhysicalSize   =
> DescriptorBlock->Descriptor[Index].PhysicalSize;
> > +    SmmAccessPrivate->SmramDesc[Index].RegionState    =
> DescriptorBlock->Descriptor[Index].RegionState;
> > +  }
> > +
> > +  SmmAccessPrivate->NumberRegions             = Index;
> > +  SmmAccessPrivate->SmmAccess.Open            = Open;
> > +  SmmAccessPrivate->SmmAccess.Close           = Close;
> > +  SmmAccessPrivate->SmmAccess.Lock            = Lock;
> > +  SmmAccessPrivate->SmmAccess.GetCapabilities = GetCapabilities;
> > +  SmmAccessPrivate->SmmAccess.LockState       = FALSE;
> > +  SmmAccessPrivate->SmmAccess.OpenState       = FALSE;
> > +
> > +  //
> > +  // Install PPI
> > +  //
> > +  PpiList->Flags  = (EFI_PEI_PPI_DESCRIPTOR_PPI |
> EFI_PEI_PPI_DESCRIPTOR_TERMINATE_LIST);
> > +  PpiList->Guid   = &gPeiSmmAccessPpiGuid;
> > +  PpiList->Ppi    = &SmmAccessPrivate->SmmAccess;
> > +
> > +  Status          = PeiServicesInstallPpi (PpiList);
> > +  ASSERT_EFI_ERROR (Status);
> > +
> > +  return EFI_SUCCESS;
> > +}
> > diff --git
> a/Silicon/Intel/IntelSiliconPkg/Feature/SmmAccess/Library/PeiSmmAccessLi
> b/PeiSmmAccessLib.inf
> >
> b/Silicon/Intel/IntelSiliconPkg/Feature/SmmAccess/Library/PeiSmmAccessLi
> b/PeiSmmAccessLib.inf
> > new file mode 100644
> > index 0000000000..0c6f5f65d8
> > --- /dev/null
> > +++
> b/Silicon/Intel/IntelSiliconPkg/Feature/SmmAccess/Library/PeiSmmAcce
> > +++ ssLib/PeiSmmAccessLib.inf
> > @@ -0,0 +1,42 @@
> > +## @file
> > +# Library description file for the SmmAccess module # # Copyright (c)
> > +2019, Intel Corporation. All rights reserved.<BR> #
> > +SPDX-License-Identifier: BSD-2-Clause-Patent # ##
> > +
> > +
> > +[Defines]
> > +INF_VERSION = 0x00010017
> > +BASE_NAME = PeiSmmAccessLib
> > +FILE_GUID = 54020881-B594-442A-8377-A57AFF98C7CF
> > +VERSION_STRING = 1.0
> > +MODULE_TYPE = PEIM
> > +LIBRARY_CLASS = SmmAccessLib
> > +
> > +
> > +[LibraryClasses]
> > +BaseLib
> > +BaseMemoryLib
> > +HobLib
> > +PciSegmentLib
> > +PeiServicesLib
> > +
> > +
> > +[Packages]
> > +MdePkg/MdePkg.dec
> > +MdeModulePkg/MdeModulePkg.dec
> > +IntelSiliconPkg/IntelSiliconPkg.dec
> > +
> > +
> > +[Sources]
> > +PeiSmmAccessLib.c
> > +
> > +
> > +[Ppis]
> > +gPeiSmmAccessPpiGuid ## PRODUCES
> > +
> > +
> > +[Guids]
> > +gEfiSmmSmramMemoryGuid
> > diff --git
> a/Silicon/Intel/IntelSiliconPkg/Feature/SmmAccess/SmmAccessDxe/SmmAc
> cess.inf
> >
> b/Silicon/Intel/IntelSiliconPkg/Feature/SmmAccess/SmmAccessDxe/SmmAc
> cess.inf
> > new file mode 100644
> > index 0000000000..b1c988844f
> > --- /dev/null
> > +++
> b/Silicon/Intel/IntelSiliconPkg/Feature/SmmAccess/SmmAccessDxe/SmmAc
> > +++ cess.inf
> > @@ -0,0 +1,47 @@
> > +## @file
> > +# Component description file for the SmmAccess module # # Copyright (c)
> > +2019, Intel Corporation. All rights reserved.<BR> #
> > +SPDX-License-Identifier: BSD-2-Clause-Patent # ##
> > +
> > +
> > +[Defines]
> > +INF_VERSION = 0x00010017
> > +BASE_NAME = SmmAccess
> > +FILE_GUID = 1323C7F8-DAD5-4126-A54B-7A05FBF41515
> > +VERSION_STRING = 1.0
> > +MODULE_TYPE = DXE_DRIVER
> > +ENTRY_POINT = SmmAccessDriverEntryPoint
> > +
> > +
> > +[LibraryClasses]
> > +UefiDriverEntryPoint
> > +BaseLib
> > +BaseMemoryLib
> > +DebugLib
> > +HobLib
> > +
> > +
> > +[Packages]
> > +MdePkg/MdePkg.dec
> > +MdeModulePkg/MdeModulePkg.dec
> > +IntelSiliconPkg/IntelSiliconPkg.dec
> > +
> > +
> > +[Sources]
> > +SmmAccessDriver.h
> > +SmmAccessDriver.c
> > +
> > +
> > +[Protocols]
> > +gEfiSmmAccess2ProtocolGuid       ## PRODUCES
> > +
> > +
> > +[Guids]
> > +gEfiSmmSmramMemoryGuid
> > +
> > +
> > +[Depex]
> > +TRUE
> > diff --git
> a/Silicon/Intel/IntelSiliconPkg/Feature/SmmAccess/SmmAccessDxe/SmmAc
> cessDriver.c
> >
> b/Silicon/Intel/IntelSiliconPkg/Feature/SmmAccess/SmmAccessDxe/SmmAc
> cessDriver.c
> > new file mode 100644
> > index 0000000000..3d3c4ab206
> > --- /dev/null
> > +++
> b/Silicon/Intel/IntelSiliconPkg/Feature/SmmAccess/SmmAccessDxe/SmmAc
> > +++ cessDriver.c
> > @@ -0,0 +1,267 @@
> > +/** @file
> > +  This is the driver that publishes the SMM Access Protocol
> > +  instance for System Agent.
> > +
> > +  Copyright (c) 2019, Intel Corporation. All rights reserved.<BR>
> > +  SPDX-License-Identifier: BSD-2-Clause-Patent
> > +
> > +**/
> > +#include "SmmAccessDriver.h"
> > +
> > +static SMM_ACCESS_PRIVATE_DATA  mSmmAccess;
> > +
> > +/**
> > +  This is the standard EFI driver point that
> > +  installs an SMM Access Protocol
> > +
> > +  @param[in] ImageHandle     - Handle for the image of this driver
> > +  @param[in] SystemTable     - Pointer to the EFI System Table
> > +
> > +  @retval EFI_SUCCESS           - Protocol was installed successfully
> > +  @exception EFI_UNSUPPORTED    - Protocol was not installed
> > +  @retval EFI_NOT_FOUND         - Protocol can't be found.
> > +  @retval EFI_OUT_OF_RESOURCES  - Protocol does not have enough
> resources to initialize the driver.
> > +**/
> > +EFI_STATUS
> > +EFIAPI
> > +SmmAccessDriverEntryPoint (
> > +  IN EFI_HANDLE         ImageHandle,
> > +  IN EFI_SYSTEM_TABLE   *SystemTable
> > +  )
> > +{
> > +  EFI_STATUS                      Status;
> > +  UINTN                           Index;
> > +  EFI_SMRAM_HOB_DESCRIPTOR_BLOCK  *DescriptorBlock;
> > +  EFI_PEI_HOB_POINTERS            *Hob;
> > +
> > +  //
> > +  // Initialize Global variables
> > +  //
> > +  ZeroMem (&mSmmAccess, sizeof (mSmmAccess));
> > +
> > +  mSmmAccess.Signature        =
> SMM_ACCESS_PRIVATE_DATA_SIGNATURE;
> > +  mSmmAccess.Handle           = NULL;
> > +
> > +  //
> > +  // Get Hob list
> > +  //
> > +  Hob = GetFirstGuidHob (&gEfiSmmSmramMemoryGuid);  if (Hob ==
> NULL) {
> > +    DEBUG ((DEBUG_WARN, "SmramMemoryReserve HOB not found\n"));
> > +    return EFI_NOT_FOUND;
> > +  }
> > +
> > +  DescriptorBlock = (VOID *) ((UINT8 *) Hob + sizeof
> > + (EFI_HOB_GUID_TYPE));
> > +
> > +  //
> > +  // Alloc space for mSmmAccess.SmramDesc  //
> mSmmAccess.SmramDesc =
> > + AllocateZeroPool ((DescriptorBlock->NumberOfSmmReservedRegions) *
> > + sizeof (EFI_SMRAM_DESCRIPTOR));  if (mSmmAccess.SmramDesc ==
> NULL) {
> > +    DEBUG ((DEBUG_WARN, "Alloc mSmmAccess.SmramDesc fail.\n"));
> > +    return EFI_OUT_OF_RESOURCES;
> > +  }
> > +
> > +  DEBUG ((DEBUG_INFO, "Alloc mSmmAccess.SmramDesc success.\n"));
> > +
> > +  //
> > +  // Use the HOB to publish SMRAM capabilities  //  for (Index = 0;
> > + Index < DescriptorBlock->NumberOfSmmReservedRegions; Index++) {
> > +    mSmmAccess.SmramDesc[Index].PhysicalStart = DescriptorBlock-
> >Descriptor[Index].PhysicalStart;
> > +    mSmmAccess.SmramDesc[Index].CpuStart      = DescriptorBlock-
> >Descriptor[Index].CpuStart;
> > +    mSmmAccess.SmramDesc[Index].PhysicalSize  = DescriptorBlock-
> >Descriptor[Index].PhysicalSize;
> > +    mSmmAccess.SmramDesc[Index].RegionState   = DescriptorBlock-
> >Descriptor[Index].RegionState;
> > +  }
> > +
> > +  mSmmAccess.NumberRegions              = Index;
> > +  mSmmAccess.SmmAccess.Open             = Open;
> > +  mSmmAccess.SmmAccess.Close            = Close;
> > +  mSmmAccess.SmmAccess.Lock             = Lock;
> > +  mSmmAccess.SmmAccess.GetCapabilities  = GetCapabilities;
> > +  mSmmAccess.SmmAccess.LockState        = FALSE;
> > +  mSmmAccess.SmmAccess.OpenState        = FALSE;
> > +
> > +  //
> > +  // Install our protocol interfaces on the device's handle  //  Status
> > + = gBS->InstallMultipleProtocolInterfaces (
> > +                  &mSmmAccess.Handle,
> > +                  &gEfiSmmAccess2ProtocolGuid,
> > +                  &mSmmAccess.SmmAccess,
> > +                  NULL
> > +                  );
> > +  if (EFI_ERROR (Status)) {
> > +    DEBUG ((DEBUG_WARN, "InstallMultipleProtocolInterfaces returned
> %r\n", Status));
> > +    return EFI_UNSUPPORTED;
> > +  }
> > +
> > +  return EFI_SUCCESS;
> > +}
> > +
> > +/**
> > +  This routine accepts a request to "open" a region of SMRAM.  The
> > +  region could be legacy ABSEG, HSEG, or TSEG near top of physical
> memory.
> > +  The use of "open" means that the memory is visible from all
> > +boot-service
> > +  and SMM agents.
> > +
> > +  @param[in] This               - Pointer to the SMM Access Interface.
> > +
> > +  @retval EFI_SUCCESS           - The region was successfully opened.
> > +  @retval EFI_DEVICE_ERROR      - The region could not be opened because
> locked by
> > +                          chipset.
> > +  @retval EFI_INVALID_PARAMETER - The descriptor index was out of
> bounds.
> > +**/
> > +EFI_STATUS
> > +EFIAPI
> > +Open (
> > +  IN EFI_SMM_ACCESS2_PROTOCOL *This
> > +  )
> > +{
> > +  SMM_ACCESS_PRIVATE_DATA *SmmAccess;
> > +  UINTN                   DescriptorIndex;
> > +
> > +  SmmAccess = SMM_ACCESS_PRIVATE_DATA_FROM_THIS (This);  for
> > + (DescriptorIndex = 0; DescriptorIndex < SmmAccess->NumberRegions;
> DescriptorIndex++) {
> > +    if (SmmAccess->SmramDesc[DescriptorIndex].RegionState &
> EFI_SMRAM_LOCKED) {
> > +      DEBUG ((DEBUG_WARN, "Cannot open a locked SMRAM region\n"));
> > +      return EFI_DEVICE_ERROR;
> > +    }
> > +  }
> > +
> > +  for (DescriptorIndex = 0; DescriptorIndex < SmmAccess-
> >NumberRegions; DescriptorIndex++) {
> > +    SmmAccess->SmramDesc[DescriptorIndex].RegionState &= (UINT64)
> ~(EFI_SMRAM_CLOSED | EFI_ALLOCATED);
> > +    SmmAccess->SmramDesc[DescriptorIndex].RegionState |= (UINT64)
> > +EFI_SMRAM_OPEN;
> > +  }
> > +  SmmAccess->SmmAccess.OpenState = TRUE;
> > +  return EFI_SUCCESS;
> > +}
> > +
> > +/**
> > +  This routine accepts a request to "close" a region of SMRAM.  The
> > +  region could be legacy AB or TSEG near top of physical memory.
> > +  The use of "close" means that the memory is only visible from SMM
> > +agents,
> > +  not from BS or RT code.
> > +
> > +  @param[in] This               - Pointer to the SMM Access Interface.
> > +
> > +  @retval EFI_SUCCESS           - The region was successfully closed.
> > +  @retval EFI_DEVICE_ERROR      - The region could not be closed because
> locked by chipset.
> > +  @retval EFI_INVALID_PARAMETER - The descriptor index was out of
> bounds.
> > +**/
> > +EFI_STATUS
> > +EFIAPI
> > +Close (
> > +  IN EFI_SMM_ACCESS2_PROTOCOL  *This
> > +  )
> > +{
> > +  SMM_ACCESS_PRIVATE_DATA *SmmAccess;
> > +  BOOLEAN                 OpenState;
> > +  UINT8                   Index;
> > +  UINTN                   DescriptorIndex;
> > +
> > +  SmmAccess = SMM_ACCESS_PRIVATE_DATA_FROM_THIS (This);
> > +
> > +  for (DescriptorIndex = 0; DescriptorIndex < SmmAccess-
> >NumberRegions; DescriptorIndex++) {
> > +    if (SmmAccess->SmramDesc[DescriptorIndex].RegionState &
> EFI_SMRAM_LOCKED) {
> > +      DEBUG ((DEBUG_WARN, "Cannot close a locked SMRAM region\n"));
> > +      continue;
> > +    }
> > +
> > +    SmmAccess->SmramDesc[DescriptorIndex].RegionState &= (UINT64)
> ~EFI_SMRAM_OPEN;
> > +    SmmAccess->SmramDesc[DescriptorIndex].RegionState |= (UINT64)
> > + (EFI_SMRAM_CLOSED | EFI_ALLOCATED);  }
> > +
> > +  //
> > +  // Find out if any regions are still open  //  OpenState = FALSE;
> > + for (Index = 0; Index < mSmmAccess.NumberRegions; Index++) {
> > +    if ((SmmAccess->SmramDesc[Index].RegionState & EFI_SMRAM_OPEN)
> == EFI_SMRAM_OPEN) {
> > +      OpenState = TRUE;
> > +    }
> > +  }
> > +
> > +  SmmAccess->SmmAccess.OpenState = OpenState;
> > +  return EFI_SUCCESS;
> > +}
> > +
> > +/**
> > +  This routine accepts a request to "lock" SMRAM.  The
> > +  region could be legacy AB or TSEG near top of physical memory.
> > +  The use of "lock" means that the memory can no longer be opened
> > +  to BS state..
> > +
> > +  @param[in] This               - Pointer to the SMM Access Interface.
> > +
> > +  @retval EFI_SUCCESS           - The region was successfully locked.
> > +  @retval EFI_DEVICE_ERROR      - The region could not be locked because
> at least
> > +                                  one range is still open.
> > +  @retval EFI_INVALID_PARAMETER - The descriptor index was out of
> bounds.
> > +**/
> > +EFI_STATUS
> > +EFIAPI
> > +Lock (
> > +  IN EFI_SMM_ACCESS2_PROTOCOL *This
> > +  )
> > +{
> > +  SMM_ACCESS_PRIVATE_DATA *SmmAccess;
> > +  UINTN                   DescriptorIndex;
> > +
> > +  SmmAccess = SMM_ACCESS_PRIVATE_DATA_FROM_THIS (This);
> > +
> > +  if (SmmAccess->SmmAccess.OpenState) {
> > +    DEBUG ((DEBUG_WARN, "Cannot lock SMRAM when SMRAM regions
> are still open\n"));
> > +    return EFI_DEVICE_ERROR;
> > +  }
> > +  for (DescriptorIndex = 0; DescriptorIndex < SmmAccess-
> >NumberRegions; DescriptorIndex++) {
> > +    SmmAccess->SmramDesc[DescriptorIndex].RegionState |=
> > + EFI_SMRAM_LOCKED;  }  SmmAccess->SmmAccess.LockState = TRUE;
> > +
> > +  return EFI_SUCCESS;
> > +}
> > +
> > +/**
> > +  This routine services a user request to discover the SMRAM
> > +  capabilities of this platform.  This will report the possible
> > +  ranges that are possible for SMRAM access, based upon the
> > +  memory controller capabilities.
> > +
> > +  @param[in] This                  - Pointer to the SMRAM Access Interface.
> > +  @param[in] SmramMapSize          - Pointer to the variable containing size
> of the
> > +                                     buffer to contain the description information.
> > +  @param[in] SmramMap              - Buffer containing the data describing the
> Smram
> > +                                     region descriptors.
> > +
> > +  @retval EFI_BUFFER_TOO_SMALL  - The user did not provide a sufficient
> buffer.
> > +  @retval EFI_SUCCESS           - The user provided a sufficiently-sized buffer.
> > +**/
> > +EFI_STATUS
> > +EFIAPI
> > +GetCapabilities (
> > +  IN CONST EFI_SMM_ACCESS2_PROTOCOL  *This,
> > +  IN OUT UINTN                       *SmramMapSize,
> > +  IN OUT EFI_SMRAM_DESCRIPTOR        *SmramMap
> > +  )
> > +{
> > +  EFI_STATUS              Status;
> > +  SMM_ACCESS_PRIVATE_DATA *SmmAccess;
> > +  UINTN                   NecessaryBufferSize;
> > +
> > +  SmmAccess           = SMM_ACCESS_PRIVATE_DATA_FROM_THIS (This);
> > +
> > +  NecessaryBufferSize = SmmAccess->NumberRegions * sizeof
> > + (EFI_SMRAM_DESCRIPTOR);
> > +
> > +  if (*SmramMapSize < NecessaryBufferSize) {
> > +    DEBUG ((DEBUG_WARN, "SMRAM Map Buffer too small\n"));
> > +    Status = EFI_BUFFER_TOO_SMALL;
> > +  } else {
> > +    CopyMem (SmramMap, SmmAccess->SmramDesc,
> NecessaryBufferSize);
> > +    Status = EFI_SUCCESS;
> > +  }
> > +
> > +  *SmramMapSize = NecessaryBufferSize;
> > +
> > +  return Status;
> > +}
> > diff --git
> a/Silicon/Intel/IntelSiliconPkg/Feature/SmmAccess/SmmAccessDxe/SmmAc
> cessDriver.h
> >
> b/Silicon/Intel/IntelSiliconPkg/Feature/SmmAccess/SmmAccessDxe/SmmAc
> cessDriver.h
> > new file mode 100644
> > index 0000000000..c0ff3a250b
> > --- /dev/null
> > +++
> b/Silicon/Intel/IntelSiliconPkg/Feature/SmmAccess/SmmAccessDxe/SmmAc
> > +++ cessDriver.h
> > @@ -0,0 +1,160 @@
> > +/** @file
> > +  Header file for SMM Access Driver.
> > +
> > +  Copyright (c) 2019, Intel Corporation. All rights reserved.<BR>
> > +  SPDX-License-Identifier: BSD-2-Clause-Patent
> > +
> > +**/
> > +#ifndef _SMM_ACCESS_DRIVER_H_
> > +#define _SMM_ACCESS_DRIVER_H_
> > +
> > +#include <Library/BaseMemoryLib.h>
> > +#include <Library/DebugLib.h>
> > +#include <Library/HobLib.h>
> > +#include <Library/PciLib.h>
> > +#include <Library/MemoryAllocationLib.h> #include
> > +<Library/UefiBootServicesTableLib.h>
> > +#include <Uefi/UefiBaseType.h>
> > +
> > +#include <Guid/SmramMemoryReserve.h>
> > +#include <Protocol/SmmAccess2.h>
> > +#include <IndustryStandard/Pci22.h>
> > +
> > +#define SMM_ACCESS_PRIVATE_DATA_SIGNATURE SIGNATURE_32 ('4',
> '5', 's',
> > +'a')
> > +
> > +///
> > +/// Private data
> > +///
> > +typedef struct {
> > +  UINTN                           Signature;
> > +  EFI_HANDLE                      Handle;
> > +  EFI_SMM_ACCESS2_PROTOCOL        SmmAccess;
> > +
> > +  ///
> > +  /// Local Data for SMM Access interface goes here
> > +  ///
> > +  UINTN                           NumberRegions;
> > +  EFI_SMRAM_DESCRIPTOR            *SmramDesc;
> > +} SMM_ACCESS_PRIVATE_DATA;
> > +
> > +#define SMM_ACCESS_PRIVATE_DATA_FROM_THIS(a) \
> > +  CR (a, \
> > +      SMM_ACCESS_PRIVATE_DATA, \
> > +      SmmAccess, \
> > +      SMM_ACCESS_PRIVATE_DATA_SIGNATURE \
> > +      )
> > +
> > +//
> > +// Prototypes
> > +// Driver model protocol interface
> > +//
> > +/**
> > +  <b>SMM Access Driver Entry Point</b>
> > +  This driver installs an SMM Access Protocol
> > +  - <b>Introduction</b> \n
> > +    This module publishes the SMM access protocol.  The protocol is used
> by the SMM Base driver to access the SMRAM region
> > when the processor is not in SMM.
> > +    The SMM Base driver uses the services provided by the SMM access
> protocol to open SMRAM during post and copy the SMM
> > handler.
> > +    SMM access protocol is also used to close the SMRAM region once the
> copying is done.
> > +    Finally, the SMM access protocol provides services to "Lock" the
> SMRAM region.
> > +    Please refer the SMM Protocols section in the attached SMM CIS
> Specification version 0.9 for further details.
> > +    This driver is required if SMM is supported. Proper configuration of
> SMM registers is recommended even if SMM is not
> > supported.
> > +
> > +  - @result
> > +    Publishes the _EFI_SMM_ACCESS_PROTOCOL: Documented in the
> System
> > + Management Mode Core Interface Specification, available at the URL:
> > + http://www.intel.com/technology/framework/spec.htm
> > +
> > +  - <b>Porting Recommendations</b> \n
> > +    No modification of this module is recommended.  Any modification
> should be done in compliance with the
> > _EFI_SMM_ACCESS_PROTOCOL protocol definition.
> > +
> > +  @param[in] ImageHandle     - Handle for the image of this driver
> > +  @param[in] SystemTable     - Pointer to the EFI System Table
> > +
> > +  @retval EFI_SUCCESS     - Protocol was installed successfully
> > +  @exception EFI_UNSUPPORTED - Protocol was not installed **/
> > +EFI_STATUS EFIAPI SmmAccessDriverEntryPoint (
> > +  IN EFI_HANDLE         ImageHandle,
> > +  IN EFI_SYSTEM_TABLE   *SystemTable
> > +  );
> > +
> > +/**
> > +  This routine accepts a request to "open" a region of SMRAM.  The
> > +  region could be legacy ABSEG, HSEG, or TSEG near top of physical
> memory.
> > +  The use of "open" means that the memory is visible from all
> > +boot-service
> > +  and SMM agents.
> > +
> > +  @param[in] This                  - Pointer to the SMM Access Interface.
> > +
> > +  @retval EFI_SUCCESS           - The region was successfully opened.
> > +  @retval EFI_DEVICE_ERROR      - The region could not be opened because
> locked by
> > +                          chipset.
> > +  @retval EFI_INVALID_PARAMETER - The descriptor index was out of
> bounds.
> > +**/
> > +EFI_STATUS
> > +EFIAPI
> > +Open (
> > +  IN EFI_SMM_ACCESS2_PROTOCOL *This
> > +  );
> > +
> > +/**
> > +  This routine accepts a request to "close" a region of SMRAM.  The
> > +  region could be legacy AB or TSEG near top of physical memory.
> > +  The use of "close" means that the memory is only visible from SMM
> > +agents,
> > +  not from BS or RT code.
> > +
> > +  @param[in] This                  - Pointer to the SMM Access Interface.
> > +
> > +  @retval EFI_SUCCESS           - The region was successfully closed.
> > +  @retval EFI_DEVICE_ERROR      - The region could not be closed because
> locked by
> > +                            chipset.
> > +  @retval EFI_INVALID_PARAMETER - The descriptor index was out of
> bounds.
> > +**/
> > +EFI_STATUS
> > +EFIAPI
> > +Close (
> > +  IN EFI_SMM_ACCESS2_PROTOCOL  *This
> > +  );
> > +
> > +/**
> > +  This routine accepts a request to "lock" SMRAM.  The
> > +  region could be legacy AB or TSEG near top of physical memory.
> > +  The use of "lock" means that the memory can no longer be opened
> > +  to BS state..
> > +
> > +  @param[in] This                  - Pointer to the SMM Access Interface.
> > +
> > +  @retval EFI_SUCCESS           - The region was successfully locked.
> > +  @retval EFI_DEVICE_ERROR      - The region could not be locked because
> at least
> > +                          one range is still open.
> > +  @retval EFI_INVALID_PARAMETER - The descriptor index was out of
> bounds.
> > +**/
> > +EFI_STATUS
> > +EFIAPI
> > +Lock (
> > +  IN EFI_SMM_ACCESS2_PROTOCOL *This
> > +  );
> > +
> > +/**
> > +  This routine services a user request to discover the SMRAM
> > +  capabilities of this platform.  This will report the possible
> > +  ranges that are possible for SMRAM access, based upon the
> > +  memory controller capabilities.
> > +
> > +  @param[in] This                  - Pointer to the SMRAM Access Interface.
> > +  @param[in] SmramMapSize          - Pointer to the variable containing size
> of the
> > +                            buffer to contain the description information.
> > +  @param[in] SmramMap              - Buffer containing the data describing the
> Smram
> > +                            region descriptors.
> > +
> > +  @retval EFI_BUFFER_TOO_SMALL  - The user did not provide a sufficient
> buffer.
> > +  @retval EFI_SUCCESS           - The user provided a sufficiently-sized buffer.
> > +**/
> > +EFI_STATUS
> > +EFIAPI
> > +GetCapabilities (
> > +  IN CONST EFI_SMM_ACCESS2_PROTOCOL  *This,
> > +  IN OUT UINTN                   *SmramMapSize,
> > +  IN OUT EFI_SMRAM_DESCRIPTOR    *SmramMap
> > +  );
> > +#endif
> > diff --git a/Silicon/Intel/IntelSiliconPkg/Include/Library/SmmAccessLib.h
> > b/Silicon/Intel/IntelSiliconPkg/Include/Library/SmmAccessLib.h
> > new file mode 100644
> > index 0000000000..b7cb88f6ca
> > --- /dev/null
> > +++ b/Silicon/Intel/IntelSiliconPkg/Include/Library/SmmAccessLib.h
> > @@ -0,0 +1,32 @@
> > +/** @file
> > +  Header file for SMM Access Driver.
> > +
> > +  Copyright (c) 2019, Intel Corporation. All rights reserved.<BR>
> > +  SPDX-License-Identifier: BSD-2-Clause-Patent
> > +
> > +**/
> > +#ifndef _SMM_ACCESS_H_
> > +#define _SMM_ACCESS_H_
> > +
> > +/**
> > +  This function is to install an SMM Access PPI
> > +  - <b>Introduction</b> \n
> > +    A module to install a PPI for controlling SMM mode memory access
> basically for S3 resume usage.
> > +
> > +  - @pre
> > +    - _PEI_MASTER_BOOT_MODE_PEIM_PPI: A PPI published by
> foundation to get bootmode executed earlier.
> > +    - _PEI_PERMANENT_MEMORY_INSTALLED_PPI: a PPI that will be
> installed after memory controller initialization completed
> > to indicate that physical memory is usable after this point.
> > +
> > +  - @result
> > +    Publish _PEI_SMM_ACCESS_PPI.
> > +
> > +    @retval EFI_SUCCESS           - Ppi successfully started and installed.
> > +    @retval EFI_NOT_FOUND         - Ppi can't be found.
> > +    @retval EFI_OUT_OF_RESOURCES  - Ppi does not have enough
> resources to initialize the driver.
> > +**/
> > +EFI_STATUS
> > +EFIAPI
> > +PeiInstallSmmAccessPpi (
> > +  VOID
> > +  );
> > +#endif
> > --
> > 2.16.2.windows.1