Re: [PATCH v2 15/16] UefiCpuPkg: CpuIo2Smm: Support of CpuIo driver under StandaloneMm

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

On 01/05/21 19:59, Kun Qin wrote:
> This change added support of CpuIo driver under StandaloneMm. The core
> services switched to gMmst based instead of gMmst. It also abstracts

(1) typo: "gMmst based instead of gMmst" -- that's the same thing

(2) renames like this should not be mixed with logic changes /
refactorings, so this would be two patches minimally

(3) in fact I disagree with renaming gSmst to gMmst (and the resultant
fallout). I see very little value in this, it only complicates the git
history, takes up reviewer resources, and risks regressions. Unless
absolutely necessary for getting the driver build in the new context, I
would strongly advise against the rename. If the rename is unavoidable,
then see (2) please -- do it in a separate patch.

(4) If I understand correctly, this is the first time when UefiCpuPkg
content is consumed in AARCH64 platforms. I wonder if that means that
the CpuIo2Smm should no longer exist under UefiCpuPkg at all. UefiCpuPkg
has been traditionally IA32/X64 only, and while the *name* of the
package certainly does not require or imply that, over time those two
things *have* become synonymous. For example, the SMM Core lives under
MdeModulePkg; I wonder if the same should happen to CpuIo2Smm as well.
Adding Ard, Leif and Mike.

Thanks
Laszlo

> standalone and traditional MM driver entrypoints into separate files to
> allow maximal common implementations.
> 
> Cc: Eric Dong <eric.dong@intel.com>
> Cc: Ray Ni <ray.ni@intel.com>
> Cc: Laszlo Ersek <lersek@redhat.com>
> Cc: Rahul Kumar <rahul1.kumar@intel.com>
> 
> Signed-off-by: Kun Qin <kun.q@outlook.com>
> ---
> 
> Notes:
>     v2:
>     - Removed "EFIAPI" for internal functions.
> 
>  UefiCpuPkg/CpuIo2Smm/{CpuIo2Smm.c => CpuIo2Common.c}           |  15 +-
>  UefiCpuPkg/CpuIo2Smm/CpuIo2Smm.c                               | 384 +-------------------
>  UefiCpuPkg/CpuIo2Smm/CpuIo2StandaloneMm.c                      |  31 ++
>  UefiCpuPkg/CpuIo2Smm/{CpuIo2Smm.h => CpuIo2Common.h}           |  17 +-
>  UefiCpuPkg/CpuIo2Smm/CpuIo2Smm.inf                             |   7 +-
>  UefiCpuPkg/CpuIo2Smm/{CpuIo2Smm.inf => CpuIo2StandaloneMm.inf} |  23 +-
>  UefiCpuPkg/UefiCpuPkg.dsc                                      |   6 +
>  7 files changed, 75 insertions(+), 408 deletions(-)
> 
> diff --git a/UefiCpuPkg/CpuIo2Smm/CpuIo2Smm.c b/UefiCpuPkg/CpuIo2Smm/CpuIo2Common.c
> similarity index 94%
> copy from UefiCpuPkg/CpuIo2Smm/CpuIo2Smm.c
> copy to UefiCpuPkg/CpuIo2Smm/CpuIo2Common.c
> index b840d3e10cae..fef434795908 100644
> --- a/UefiCpuPkg/CpuIo2Smm/CpuIo2Smm.c
> +++ b/UefiCpuPkg/CpuIo2Smm/CpuIo2Common.c
> @@ -6,7 +6,7 @@ SPDX-License-Identifier: BSD-2-Clause-Patent
>  
>  **/
>  
> -#include "CpuIo2Smm.h"
> +#include "CpuIo2Common.h"
>  
>  //
>  // Handle for the SMM CPU I/O Protocol
> @@ -371,18 +371,13 @@ CpuIoServiceWrite (
>  /**
>    The module Entry Point SmmCpuIoProtocol driver
>  
> -  @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 is executed successfully.
>    @retval Other        Some error occurs when executing this entry point.
>  
>  **/
>  EFI_STATUS
> -EFIAPI
> -SmmCpuIo2Initialize (
> -  IN EFI_HANDLE        ImageHandle,
> -  IN EFI_SYSTEM_TABLE  *SystemTable
> +CommonCpuIo2Initialize (
> +  VOID
>    )
>  {
>    EFI_STATUS  Status;
> @@ -390,12 +385,12 @@ SmmCpuIo2Initialize (
>    //
>    // Copy the SMM CPU I/O Protocol instance into the System Management System Table
>    //
> -  CopyMem (&gSmst->SmmIo, &mSmmCpuIo2, sizeof (mSmmCpuIo2));
> +  CopyMem (&gMmst->MmIo, &mSmmCpuIo2, sizeof (mSmmCpuIo2));
>  
>    //
>    // Install the SMM CPU I/O Protocol into the SMM protocol database
>    //
> -  Status = gSmst->SmmInstallProtocolInterface (
> +  Status = gMmst->MmInstallProtocolInterface (
>                      &mHandle,
>                      &gEfiSmmCpuIo2ProtocolGuid,
>                      EFI_NATIVE_INTERFACE,
> diff --git a/UefiCpuPkg/CpuIo2Smm/CpuIo2Smm.c b/UefiCpuPkg/CpuIo2Smm/CpuIo2Smm.c
> index b840d3e10cae..062d1a47a09f 100644
> --- a/UefiCpuPkg/CpuIo2Smm/CpuIo2Smm.c
> +++ b/UefiCpuPkg/CpuIo2Smm/CpuIo2Smm.c
> @@ -6,367 +6,9 @@ SPDX-License-Identifier: BSD-2-Clause-Patent
>  
>  **/
>  
> -#include "CpuIo2Smm.h"
> +#include <PiSmm.h>
>  
> -//
> -// Handle for the SMM CPU I/O Protocol
> -//
> -EFI_HANDLE  mHandle = NULL;
> -
> -//
> -// SMM CPU I/O Protocol instance
> -//
> -EFI_SMM_CPU_IO2_PROTOCOL mSmmCpuIo2 = {
> -  {
> -    CpuMemoryServiceRead,
> -    CpuMemoryServiceWrite
> -  },
> -  {
> -    CpuIoServiceRead,
> -    CpuIoServiceWrite
> -  }
> -};
> -
> -//
> -// Lookup table for increment values based on transfer widths
> -//
> -UINT8 mStride[] = {
> -  1, // SMM_IO_UINT8
> -  2, // SMM_IO_UINT16
> -  4, // SMM_IO_UINT32
> -  8  // SMM_IO_UINT64
> -};
> -
> -/**
> -  Check parameters to a SMM CPU I/O Protocol service request.
> -
> -  @param[in]  MmioOperation  TRUE for an MMIO operation, FALSE for I/O Port operation.
> -  @param[in]  Width          Signifies the width of the I/O operations.
> -  @param[in]  Address        The base address of the I/O operations.  The caller is
> -                             responsible for aligning the Address if required.
> -  @param[in]  Count          The number of I/O operations to perform.
> -  @param[in]  Buffer         For read operations, the destination buffer to store
> -                             the results.  For write operations, the source buffer
> -                             from which to write data.
> -
> -  @retval EFI_SUCCESS            The data was read from or written to the device.
> -  @retval EFI_UNSUPPORTED        The Address is not valid for this system.
> -  @retval EFI_INVALID_PARAMETER  Width or Count, or both, were invalid.
> -
> -**/
> -EFI_STATUS
> -CpuIoCheckParameter (
> -  IN BOOLEAN           MmioOperation,
> -  IN EFI_SMM_IO_WIDTH  Width,
> -  IN UINT64            Address,
> -  IN UINTN             Count,
> -  IN VOID              *Buffer
> -  )
> -{
> -  UINT64  MaxCount;
> -  UINT64  Limit;
> -
> -  //
> -  // Check to see if Buffer is NULL
> -  //
> -  if (Buffer == NULL) {
> -    return EFI_INVALID_PARAMETER;
> -  }
> -
> -  //
> -  // Check to see if Width is in the valid range
> -  //
> -  if ((UINT32)Width > SMM_IO_UINT64) {
> -    return EFI_INVALID_PARAMETER;
> -  }
> -
> -  //
> -  // Check to see if Width is in the valid range for I/O Port operations
> -  //
> -  if (!MmioOperation && (Width == SMM_IO_UINT64)) {
> -    return EFI_INVALID_PARAMETER;
> -  }
> -
> -  //
> -  // Check to see if any address associated with this transfer exceeds the maximum
> -  // allowed address.  The maximum address implied by the parameters passed in is
> -  // Address + Size * Count.  If the following condition is met, then the transfer
> -  // is not supported.
> -  //
> -  //    Address + Size * Count > (MmioOperation ? MAX_ADDRESS : MAX_IO_PORT_ADDRESS) + 1
> -  //
> -  // Since MAX_ADDRESS can be the maximum integer value supported by the CPU and Count
> -  // can also be the maximum integer value supported by the CPU, this range
> -  // check must be adjusted to avoid all overflow conditions.
> -  //
> -  // The following form of the range check is equivalent but assumes that
> -  // MAX_ADDRESS and MAX_IO_PORT_ADDRESS are of the form (2^n - 1).
> -  //
> -  Limit = (MmioOperation ? MAX_ADDRESS : MAX_IO_PORT_ADDRESS);
> -  if (Count == 0) {
> -    if (Address > Limit) {
> -      return EFI_UNSUPPORTED;
> -    }
> -  } else {
> -    MaxCount = RShiftU64 (Limit, Width);
> -    if (MaxCount < (Count - 1)) {
> -      return EFI_UNSUPPORTED;
> -    }
> -    if (Address > LShiftU64 (MaxCount - Count + 1, Width)) {
> -      return EFI_UNSUPPORTED;
> -    }
> -  }
> -
> -  //
> -  // Check to see if Address is aligned
> -  //
> -  if ((Address & ((UINT64)mStride[Width] - 1)) != 0) {
> -    return EFI_UNSUPPORTED;
> -  }
> -
> -  return EFI_SUCCESS;
> -}
> -
> -/**
> -  Reads memory-mapped registers.
> -
> -  The I/O operations are carried out exactly as requested.  The caller is
> -  responsible for any alignment and I/O width issues that the bus, device,
> -  platform, or type of I/O might require.
> -
> -  @param[in]  This     The EFI_SMM_CPU_IO2_PROTOCOL instance.
> -  @param[in]  Width    Signifies the width of the I/O operations.
> -  @param[in]  Address  The base address of the I/O operations.  The caller is
> -                       responsible for aligning the Address if required.
> -  @param[in]  Count    The number of I/O operations to perform.
> -  @param[out] Buffer   For read operations, the destination buffer to store
> -                       the results.  For write operations, the source buffer
> -                       from which to write data.
> -
> -  @retval EFI_SUCCESS            The data was read from or written to the device.
> -  @retval EFI_UNSUPPORTED        The Address is not valid for this system.
> -  @retval EFI_INVALID_PARAMETER  Width or Count, or both, were invalid.
> -  @retval EFI_OUT_OF_RESOURCES   The request could not be completed due to a
> -                                 lack of resources
> -
> -**/
> -EFI_STATUS
> -EFIAPI
> -CpuMemoryServiceRead (
> -  IN  CONST EFI_SMM_CPU_IO2_PROTOCOL  *This,
> -  IN  EFI_SMM_IO_WIDTH                Width,
> -  IN  UINT64                          Address,
> -  IN  UINTN                           Count,
> -  OUT VOID                            *Buffer
> -  )
> -{
> -  EFI_STATUS  Status;
> -  UINT8       Stride;
> -  UINT8       *Uint8Buffer;
> -
> -  Status = CpuIoCheckParameter (TRUE, Width, Address, Count, Buffer);
> -  if (EFI_ERROR (Status)) {
> -    return Status;
> -  }
> -
> -  //
> -  // Select loop based on the width of the transfer
> -  //
> -  Stride = mStride[Width];
> -  for (Uint8Buffer = Buffer; Count > 0; Address += Stride, Uint8Buffer += Stride, Count--) {
> -    if (Width == SMM_IO_UINT8) {
> -      *Uint8Buffer = MmioRead8 ((UINTN)Address);
> -    } else if (Width == SMM_IO_UINT16) {
> -      *((UINT16 *)Uint8Buffer) = MmioRead16 ((UINTN)Address);
> -    } else if (Width == SMM_IO_UINT32) {
> -      *((UINT32 *)Uint8Buffer) = MmioRead32 ((UINTN)Address);
> -    } else if (Width == SMM_IO_UINT64) {
> -      *((UINT64 *)Uint8Buffer) = MmioRead64 ((UINTN)Address);
> -    }
> -  }
> -  return EFI_SUCCESS;
> -}
> -
> -/**
> -  Writes memory-mapped registers.
> -
> -  The I/O operations are carried out exactly as requested.  The caller is
> -  responsible for any alignment and I/O width issues that the bus, device,
> -  platform, or type of I/O might require.
> -
> -  @param[in]  This     The EFI_SMM_CPU_IO2_PROTOCOL instance.
> -  @param[in]  Width    Signifies the width of the I/O operations.
> -  @param[in]  Address  The base address of the I/O operations.  The caller is
> -                       responsible for aligning the Address if required.
> -  @param[in]  Count    The number of I/O operations to perform.
> -  @param[in]  Buffer   For read operations, the destination buffer to store
> -                       the results.  For write operations, the source buffer
> -                       from which to write data.
> -
> -  @retval EFI_SUCCESS            The data was read from or written to the device.
> -  @retval EFI_UNSUPPORTED        The Address is not valid for this system.
> -  @retval EFI_INVALID_PARAMETER  Width or Count, or both, were invalid.
> -  @retval EFI_OUT_OF_RESOURCES   The request could not be completed due to a
> -                                 lack of resources
> -
> -**/
> -EFI_STATUS
> -EFIAPI
> -CpuMemoryServiceWrite (
> -  IN CONST EFI_SMM_CPU_IO2_PROTOCOL  *This,
> -  IN EFI_SMM_IO_WIDTH                Width,
> -  IN UINT64                          Address,
> -  IN UINTN                           Count,
> -  IN VOID                            *Buffer
> -  )
> -{
> -  EFI_STATUS  Status;
> -  UINT8       Stride;
> -  UINT8       *Uint8Buffer;
> -
> -  Status = CpuIoCheckParameter (TRUE, Width, Address, Count, Buffer);
> -  if (EFI_ERROR (Status)) {
> -    return Status;
> -  }
> -
> -  //
> -  // Select loop based on the width of the transfer
> -  //
> -  Stride = mStride[Width];
> -  for (Uint8Buffer = Buffer; Count > 0; Address += Stride, Uint8Buffer += Stride, Count--) {
> -    if (Width == SMM_IO_UINT8) {
> -      MmioWrite8 ((UINTN)Address, *Uint8Buffer);
> -    } else if (Width == SMM_IO_UINT16) {
> -      MmioWrite16 ((UINTN)Address, *((UINT16 *)Uint8Buffer));
> -    } else if (Width == SMM_IO_UINT32) {
> -      MmioWrite32 ((UINTN)Address, *((UINT32 *)Uint8Buffer));
> -    } else if (Width == SMM_IO_UINT64) {
> -      MmioWrite64 ((UINTN)Address, *((UINT64 *)Uint8Buffer));
> -    }
> -  }
> -  return EFI_SUCCESS;
> -}
> -
> -/**
> -  Reads I/O registers.
> -
> -  The I/O operations are carried out exactly as requested.  The caller is
> -  responsible for any alignment and I/O width issues that the bus, device,
> -  platform, or type of I/O might require.
> -
> -  @param[in]  This     The EFI_SMM_CPU_IO2_PROTOCOL instance.
> -  @param[in]  Width    Signifies the width of the I/O operations.
> -  @param[in]  Address  The base address of the I/O operations.  The caller is
> -                       responsible for aligning the Address if required.
> -  @param[in]  Count    The number of I/O operations to perform.
> -  @param[out] Buffer   For read operations, the destination buffer to store
> -                       the results.  For write operations, the source buffer
> -                       from which to write data.
> -
> -  @retval EFI_SUCCESS            The data was read from or written to the device.
> -  @retval EFI_UNSUPPORTED        The Address is not valid for this system.
> -  @retval EFI_INVALID_PARAMETER  Width or Count, or both, were invalid.
> -  @retval EFI_OUT_OF_RESOURCES   The request could not be completed due to a
> -                                 lack of resources
> -
> -**/
> -EFI_STATUS
> -EFIAPI
> -CpuIoServiceRead (
> -  IN  CONST EFI_SMM_CPU_IO2_PROTOCOL  *This,
> -  IN  EFI_SMM_IO_WIDTH                Width,
> -  IN  UINT64                          Address,
> -  IN  UINTN                           Count,
> -  OUT VOID                            *Buffer
> -  )
> -{
> -  EFI_STATUS  Status;
> -  UINT8       Stride;
> -  UINT8       *Uint8Buffer;
> -
> -  Status = CpuIoCheckParameter (FALSE, Width, Address, Count, Buffer);
> -  if (EFI_ERROR (Status)) {
> -    return Status;
> -  }
> -
> -  //
> -  // Select loop based on the width of the transfer
> -  //
> -  Stride = mStride[Width];
> -  for (Uint8Buffer = Buffer; Count > 0; Address += Stride, Uint8Buffer += Stride, Count--) {
> -    if (Width == SMM_IO_UINT8) {
> -      *Uint8Buffer = IoRead8 ((UINTN)Address);
> -    } else if (Width == SMM_IO_UINT16) {
> -      *((UINT16 *)Uint8Buffer) = IoRead16 ((UINTN)Address);
> -    } else if (Width == SMM_IO_UINT32) {
> -      *((UINT32 *)Uint8Buffer) = IoRead32 ((UINTN)Address);
> -    }
> -  }
> -
> -  return EFI_SUCCESS;
> -}
> -
> -/**
> -  Write I/O registers.
> -
> -  The I/O operations are carried out exactly as requested.  The caller is
> -  responsible for any alignment and I/O width issues that the bus, device,
> -  platform, or type of I/O might require.
> -
> -  @param[in]  This     The EFI_SMM_CPU_IO2_PROTOCOL instance.
> -  @param[in]  Width    Signifies the width of the I/O operations.
> -  @param[in]  Address  The base address of the I/O operations.  The caller is
> -                       responsible for aligning the Address if required.
> -  @param[in]  Count    The number of I/O operations to perform.
> -  @param[in]  Buffer   For read operations, the destination buffer to store
> -                       the results.  For write operations, the source buffer
> -                       from which to write data.
> -
> -  @retval EFI_SUCCESS            The data was read from or written to the device.
> -  @retval EFI_UNSUPPORTED        The Address is not valid for this system.
> -  @retval EFI_INVALID_PARAMETER  Width or Count, or both, were invalid.
> -  @retval EFI_OUT_OF_RESOURCES   The request could not be completed due to a
> -                                 lack of resources
> -
> -**/
> -EFI_STATUS
> -EFIAPI
> -CpuIoServiceWrite (
> -  IN CONST EFI_SMM_CPU_IO2_PROTOCOL  *This,
> -  IN EFI_SMM_IO_WIDTH                Width,
> -  IN UINT64                          Address,
> -  IN UINTN                           Count,
> -  IN VOID                            *Buffer
> -  )
> -{
> -  EFI_STATUS  Status;
> -  UINT8       Stride;
> -  UINT8       *Uint8Buffer;
> -
> -  //
> -  // Make sure the parameters are valid
> -  //
> -  Status = CpuIoCheckParameter (FALSE, Width, Address, Count, Buffer);
> -  if (EFI_ERROR (Status)) {
> -    return Status;
> -  }
> -
> -  //
> -  // Select loop based on the width of the transfer
> -  //
> -  Stride = mStride[Width];
> -  for (Uint8Buffer = (UINT8 *)Buffer; Count > 0; Address += Stride, Uint8Buffer += Stride, Count--) {
> -    if (Width == SMM_IO_UINT8) {
> -      IoWrite8 ((UINTN)Address, *Uint8Buffer);
> -    } else if (Width == SMM_IO_UINT16) {
> -      IoWrite16 ((UINTN)Address, *((UINT16 *)Uint8Buffer));
> -    } else if (Width == SMM_IO_UINT32) {
> -      IoWrite32 ((UINTN)Address, *((UINT32 *)Uint8Buffer));
> -    }
> -  }
> -
> -  return EFI_SUCCESS;
> -}
> +#include "CpuIo2Common.h"
>  
>  /**
>    The module Entry Point SmmCpuIoProtocol driver
> @@ -380,28 +22,10 @@ CpuIoServiceWrite (
>  **/
>  EFI_STATUS
>  EFIAPI
> -SmmCpuIo2Initialize (
> +TraditionalMmCpuIo2Initialize (
>    IN EFI_HANDLE        ImageHandle,
>    IN EFI_SYSTEM_TABLE  *SystemTable
>    )
>  {
> -  EFI_STATUS  Status;
> -
> -  //
> -  // Copy the SMM CPU I/O Protocol instance into the System Management System Table
> -  //
> -  CopyMem (&gSmst->SmmIo, &mSmmCpuIo2, sizeof (mSmmCpuIo2));
> -
> -  //
> -  // Install the SMM CPU I/O Protocol into the SMM protocol database
> -  //
> -  Status = gSmst->SmmInstallProtocolInterface (
> -                    &mHandle,
> -                    &gEfiSmmCpuIo2ProtocolGuid,
> -                    EFI_NATIVE_INTERFACE,
> -                    &mSmmCpuIo2
> -                    );
> -  ASSERT_EFI_ERROR (Status);
> -
> -  return Status;
> +  return CommonCpuIo2Initialize ();
>  }
> diff --git a/UefiCpuPkg/CpuIo2Smm/CpuIo2StandaloneMm.c b/UefiCpuPkg/CpuIo2Smm/CpuIo2StandaloneMm.c
> new file mode 100644
> index 000000000000..2978f82eb815
> --- /dev/null
> +++ b/UefiCpuPkg/CpuIo2Smm/CpuIo2StandaloneMm.c
> @@ -0,0 +1,31 @@
> +/** @file
> +  Produces the SMM CPU I/O Protocol.
> +
> +Copyright (c) 2009 - 2018, Intel Corporation. All rights reserved.<BR>
> +SPDX-License-Identifier: BSD-2-Clause-Patent
> +
> +**/
> +
> +#include <PiMm.h>
> +
> +#include "CpuIo2Common.h"
> +
> +/**
> +  The module Entry Point SmmCpuIoProtocol driver
> +
> +  @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 is executed successfully.
> +  @retval Other        Some error occurs when executing this entry point.
> +
> +**/
> +EFI_STATUS
> +EFIAPI
> +StandaloneMmCpuIo2Initialize (
> +  IN EFI_HANDLE           ImageHandle,
> +  IN EFI_MM_SYSTEM_TABLE  *SystemTable
> +  )
> +{
> +  return CommonCpuIo2Initialize ();
> +}
> diff --git a/UefiCpuPkg/CpuIo2Smm/CpuIo2Smm.h b/UefiCpuPkg/CpuIo2Smm/CpuIo2Common.h
> similarity index 92%
> rename from UefiCpuPkg/CpuIo2Smm/CpuIo2Smm.h
> rename to UefiCpuPkg/CpuIo2Smm/CpuIo2Common.h
> index 4c133b58c9f4..6759cc1c8777 100644
> --- a/UefiCpuPkg/CpuIo2Smm/CpuIo2Smm.h
> +++ b/UefiCpuPkg/CpuIo2Smm/CpuIo2Common.h
> @@ -9,14 +9,14 @@ SPDX-License-Identifier: BSD-2-Clause-Patent
>  #ifndef _CPU_IO2_SMM_H_
>  #define _CPU_IO2_SMM_H_
>  
> -#include <PiSmm.h>
> +#include <PiMm.h>
>  
>  #include <Protocol/SmmCpuIo2.h>
>  
>  #include <Library/BaseLib.h>
>  #include <Library/DebugLib.h>
>  #include <Library/IoLib.h>
> -#include <Library/SmmServicesTableLib.h>
> +#include <Library/MmServicesTableLib.h>
>  #include <Library/BaseMemoryLib.h>
>  
>  #define MAX_IO_PORT_ADDRESS   0xFFFF
> @@ -153,4 +153,17 @@ CpuIoServiceWrite (
>    IN VOID                            *Buffer
>    );
>  
> +
> +/**
> +  The module Entry Point SmmCpuIoProtocol driver
> +
> +  @retval EFI_SUCCESS  The entry point is executed successfully.
> +  @retval Other        Some error occurs when executing this entry point.
> +
> +**/
> +EFI_STATUS
> +CommonCpuIo2Initialize (
> +  VOID
> +  );
> +
>  #endif
> diff --git a/UefiCpuPkg/CpuIo2Smm/CpuIo2Smm.inf b/UefiCpuPkg/CpuIo2Smm/CpuIo2Smm.inf
> index bc78fa4e42d2..031db1d100b9 100644
> --- a/UefiCpuPkg/CpuIo2Smm/CpuIo2Smm.inf
> +++ b/UefiCpuPkg/CpuIo2Smm/CpuIo2Smm.inf
> @@ -14,7 +14,7 @@ [Defines]
>    MODULE_TYPE                    = DXE_SMM_DRIVER
>    VERSION_STRING                 = 1.0
>    PI_SPECIFICATION_VERSION       = 0x0001000A
> -  ENTRY_POINT                    = SmmCpuIo2Initialize
> +  ENTRY_POINT                    = TraditionalMmCpuIo2Initialize
>  
>  #
>  # The following information is for reference only and not required by the build tools.
> @@ -24,7 +24,8 @@ [Defines]
>  
>  [Sources]
>    CpuIo2Smm.c
> -  CpuIo2Smm.h
> +  CpuIo2Common.c
> +  CpuIo2Common.h
>  
>  [Packages]
>    MdePkg/MdePkg.dec
> @@ -34,7 +35,7 @@ [LibraryClasses]
>    BaseLib
>    DebugLib
>    IoLib
> -  SmmServicesTableLib
> +  MmServicesTableLib
>    BaseMemoryLib
>  
>  [Protocols]
> diff --git a/UefiCpuPkg/CpuIo2Smm/CpuIo2Smm.inf b/UefiCpuPkg/CpuIo2Smm/CpuIo2StandaloneMm.inf
> similarity index 56%
> copy from UefiCpuPkg/CpuIo2Smm/CpuIo2Smm.inf
> copy to UefiCpuPkg/CpuIo2Smm/CpuIo2StandaloneMm.inf
> index bc78fa4e42d2..cce7742bee7a 100644
> --- a/UefiCpuPkg/CpuIo2Smm/CpuIo2Smm.inf
> +++ b/UefiCpuPkg/CpuIo2Smm/CpuIo2StandaloneMm.inf
> @@ -8,13 +8,12 @@
>  
>  [Defines]
>    INF_VERSION                    = 0x00010005
> -  BASE_NAME                      = CpuIo2Smm
> -  MODULE_UNI_FILE                = CpuIo2Smm.uni
> -  FILE_GUID                      = A47EE2D8-F60E-42fd-8E58-7BD65EE4C29B
> -  MODULE_TYPE                    = DXE_SMM_DRIVER
> +  BASE_NAME                      = CpuIo2StandaloneMm
> +  FILE_GUID                      = E3121A26-BB1C-4A18-8E23-2EA3F0412248
> +  MODULE_TYPE                    = MM_STANDALONE
>    VERSION_STRING                 = 1.0
> -  PI_SPECIFICATION_VERSION       = 0x0001000A
> -  ENTRY_POINT                    = SmmCpuIo2Initialize
> +  PI_SPECIFICATION_VERSION       = 0x00010032
> +  ENTRY_POINT                    = StandaloneMmCpuIo2Initialize
>  
>  #
>  # The following information is for reference only and not required by the build tools.
> @@ -23,18 +22,19 @@ [Defines]
>  #
>  
>  [Sources]
> -  CpuIo2Smm.c
> -  CpuIo2Smm.h
> +  CpuIo2StandaloneMm.c
> +  CpuIo2Common.c
> +  CpuIo2Common.h
>  
>  [Packages]
>    MdePkg/MdePkg.dec
>  
>  [LibraryClasses]
> -  UefiDriverEntryPoint
> +  StandaloneMmDriverEntryPoint
>    BaseLib
>    DebugLib
>    IoLib
> -  SmmServicesTableLib
> +  MmServicesTableLib
>    BaseMemoryLib
>  
>  [Protocols]
> @@ -42,6 +42,3 @@ [Protocols]
>  
>  [Depex]
>    TRUE
> -
> -[UserExtensions.TianoCore."ExtraFiles"]
> -  CpuIo2SmmExtra.uni
> diff --git a/UefiCpuPkg/UefiCpuPkg.dsc b/UefiCpuPkg/UefiCpuPkg.dsc
> index b2b6d78a71b0..4e46c600788f 100644
> --- a/UefiCpuPkg/UefiCpuPkg.dsc
> +++ b/UefiCpuPkg/UefiCpuPkg.dsc
> @@ -38,6 +38,7 @@ [LibraryClasses]
>    UefiRuntimeServicesTableLib|MdePkg/Library/UefiRuntimeServicesTableLib/UefiRuntimeServicesTableLib.inf
>    UefiBootServicesTableLib|MdePkg/Library/UefiBootServicesTableLib/UefiBootServicesTableLib.inf
>    UefiDriverEntryPoint|MdePkg/Library/UefiDriverEntryPoint/UefiDriverEntryPoint.inf
> +  StandaloneMmDriverEntryPoint|MdePkg/Library/StandaloneMmDriverEntryPoint/StandaloneMmDriverEntryPoint.inf
>    DxeServicesTableLib|MdePkg/Library/DxeServicesTableLib/DxeServicesTableLib.inf
>    PeimEntryPoint|MdePkg/Library/PeimEntryPoint/PeimEntryPoint.inf
>    PeiServicesLib|MdePkg/Library/PeiServicesLib/PeiServicesLib.inf
> @@ -89,10 +90,14 @@ [LibraryClasses.common.DXE_DRIVER]
>  
>  [LibraryClasses.common.DXE_SMM_DRIVER]
>    SmmServicesTableLib|MdePkg/Library/SmmServicesTableLib/SmmServicesTableLib.inf
> +  MmServicesTableLib|MdePkg/Library/MmServicesTableLib/MmServicesTableLib.inf
>    MemoryAllocationLib|MdePkg/Library/SmmMemoryAllocationLib/SmmMemoryAllocationLib.inf
>    HobLib|MdePkg/Library/DxeHobLib/DxeHobLib.inf
>    CpuExceptionHandlerLib|UefiCpuPkg/Library/CpuExceptionHandlerLib/SmmCpuExceptionHandlerLib.inf
>  
> +[LibraryClasses.common.MM_STANDALONE]
> +  MmServicesTableLib|MdePkg/Library/StandaloneMmServicesTableLib/StandaloneMmServicesTableLib.inf
> +
>  [LibraryClasses.common.UEFI_APPLICATION]
>    UefiApplicationEntryPoint|MdePkg/Library/UefiApplicationEntryPoint/UefiApplicationEntryPoint.inf
>    MemoryAllocationLib|MdePkg/Library/UefiMemoryAllocationLib/UefiMemoryAllocationLib.inf
> @@ -121,6 +126,7 @@ [Components.IA32, Components.X64]
>        NULL|UefiCpuPkg/Library/CpuCommonFeaturesLib/CpuCommonFeaturesLib.inf
>    }
>    UefiCpuPkg/CpuIo2Smm/CpuIo2Smm.inf
> +  UefiCpuPkg/CpuIo2Smm/CpuIo2StandaloneMm.inf
>    UefiCpuPkg/CpuMpPei/CpuMpPei.inf
>    UefiCpuPkg/CpuS3DataDxe/CpuS3DataDxe.inf
>    UefiCpuPkg/Library/BaseUefiCpuLib/BaseUefiCpuLib.inf
>