Re: [edk2-devel] [PATCH v1 1/2] UefiCpuPkg: Extend SMM CPU Service with rendezvous support.

["Li, Zhihao" <zhihao.li@intel.com>]

Hi, Michael
With your comment:
1. Decide to define a new Protocol with just the new services(gEdkiiSmmCpuRedezvousProtocolGuid)
2. Modified it to 0x00.
3. keep v1
4. keep v1
Other modification:
1. SmmCpuRendezvousLib.inf: add MM_STANDALONE support
2. SmmCpuRendezvousLib.c: remove *constructor function, move its
action into  SmmWaitForAllProcessor function.

> -----Original Message-----
> From: Fu, Siyuan <siyuan.fu@intel.com>
> Sent: Thursday, February 10, 2022 4:19 PM
> To: devel@edk2.groups.io; Kinney, Michael D <michael.d.kinney@intel.com>;
> Li, Zhihao <zhihao.li@intel.com>; Ni, Ray <ray.ni@intel.com>
> Cc: Dong, Eric <eric.dong@intel.com>; Kumar, Rahul1
> <Rahul1.Kumar@intel.com>
> Subject: RE: [edk2-devel] [PATCH v1 1/2] UefiCpuPkg: Extend SMM CPU
> Service with rendezvous support.
> 
> Hi, Mike
> 
> > -----Original Message-----
> > From: devel@edk2.groups.io <devel@edk2.groups.io> On Behalf Of
> Michael
> > D Kinney
> > Sent: 2022年2月9日 0:31
> > To: devel@edk2.groups.io; Li, Zhihao <zhihao.li@intel.com>; Kinney,
> > Michael D <michael.d.kinney@intel.com>
> > Cc: Dong, Eric <eric.dong@intel.com>; Ni, Ray <ray.ni@intel.com>;
> > Kumar,
> > Rahul1 <rahul1.kumar@intel.com>
> > Subject: Re: [edk2-devel] [PATCH v1 1/2] UefiCpuPkg: Extend SMM CPU
> > Service with rendezvous support.
> >
> > Hi Zhihao,
> >
> > gEfiSmmCpuServiceProtocolGuid is defined in the UefiCpuPkg and is
> > already an EDK II specific feature protocol.  Adding an Edkii names
> > version of the protocol does not make it clear that there is a
> > relationship between the two versions of this protocol.  You have
> > added one new service to the existing protocol.  The existing protocol
> > does not have a Revision field so we do have to create a new Protocol
> > Name/Protocol GUID.  Based on previous use cases, we have a few options:
> >
> > 1) If Revision field is present, add to end and increase Revision
> > value
> > 2) If Revision field not present
> >   a) Define an _2 or _Ex version of the protocol with new service(s) added
> >      to end of structure and implement original version of the protocol on
> >      top of the _2 version of the protocol.
> >   b) Define a new Protocol with just the new services. (e.g.
> > gEdkiiSmmCpuRedezvousProtocolGuid)
> We previously discussed with Ray when deciding the protocol name and
> choose the edk2 prefix.
> @Ni, Ray
> Any opinion on using an _Ex version protocol name or a separate protocol?
Decide to define a new Protocol with just the new services(gEdkiiSmmCpuRedezvousProtocolGuid)
> 
> >
> > The patch also changes the DEC default value of
> > gUefiCpuPkgTokenSpaceGuid.PcdCpuSmmSyncMode
> > from 0x00 to 0x01.  Changing the default value of a PCD in a DEC file
> > is a non backwards compatible change.  This should not be done.
> > Instead, platforms that need the different sync mode should set that
> > PCD in their DSC file.
Modified it to 0x00.
> >
> > Is a new lib class really required at this time.  The reason to add a
> > new lib class is if there are multiple consumers.
> There are lots of consumers but no in edk2 repo, mostly inside platform code
> like edk2platforms.
> Technically the SMI handler which require all processors in SMM mode to
> complete its task (either due to security consideration or hardware/silicon
> restriction) will need to consume this library interface to complete the
> rendezvous in relax AP mode.
> 
> >
> > I see the lib instance uses a RegisterProtocolNotify in its
> > constructor.  Is it possible to use a Depex instead and eliminate the
> > additional complexity of a constructor and RegisterProtocolNotify?
> We can't use Depex since this is an optional protocol. It's not required to
> those platforms which only have traditional sync mode support.
> 
> Thanks,
> Siyuan
> 
> >
> > Best regards,
> >
> > Mike
> >
> > > -----Original Message-----
> > > From: devel@edk2.groups.io <devel@edk2.groups.io> On Behalf Of Li,
> > > Zhihao
> > > Sent: Monday, February 7, 2022 9:36 PM
> > > To: devel@edk2.groups.io
> > > Cc: Dong, Eric <eric.dong@intel.com>; Ni, Ray <ray.ni@intel.com>;
> > > Kumar,
> > Rahul1 <rahul1.kumar@intel.com>
> > > Subject: [edk2-devel] [PATCH v1 1/2] UefiCpuPkg: Extend SMM CPU
> > > Service
> > with rendezvous support.
> > >
> > > From: Zhihao Li <zhihao.li@intel.com>
> > >
> > > REF： https://bugzilla.tianocore.org/show_bug.cgi?id=3815
> > >
> > > This patch extends the SMM CPU Service protocol with new interface
> > > SmmWaitForAllProcessor(), which can be used by SMI handler to
> > > optionally wait for other APs to complete SMM rendezvous in relaxed AP
> mode.
> > >
> > > A new library SmmCpuRendezvousLib is provided to abstract the
> > > service into library API to simple SMI handler code.
> > >
> > > Cc: Eric Dong <eric.dong@intel.com>
> > > Cc: Ray Ni <ray.ni@intel.com>
> > > Cc: Rahul Kumar <rahul1.kumar@intel.com>
> > >
> > > Signed-off-by: Zhihao Li <zhihao.li@intel.com>
> > > ---
> > >  UefiCpuPkg/Library/SmmCpuRendezvousLib/SmmCpuRendezvousLib.c
> | 109
> > ++++++++++++++++++++
> > >  UefiCpuPkg/PiSmmCpuDxeSmm/CpuService.c                         |  65
> > ++++++++++++
> > >  UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c                          |  14 ++-
> > >  UefiCpuPkg/PiSmmCpuDxeSmm/SyncTimer.c                          |   2 +-
> > >  UefiCpuPkg/Include/Library/SmmCpuRendezvousLib.h               |  27
> +++++
> > >  UefiCpuPkg/Include/Protocol/SmmCpuService.h                    |  40 +++++++
> > >  UefiCpuPkg/Library/SmmCpuRendezvousLib/SmmCpuRendezvousLib.inf
> |
> > > 32
> > ++++++
> > >  UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.h                     |  28
> +++++
> > >  UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.inf                   |   3 +-
> > >  UefiCpuPkg/UefiCpuPkg.dec                                      |   5 +-
> > >  10 files changed, 318 insertions(+), 7 deletions(-)
> > >
> > > diff --git
> > a/UefiCpuPkg/Library/SmmCpuRendezvousLib/SmmCpuRendezvousLib.c
> > >
> b/UefiCpuPkg/Library/SmmCpuRendezvousLib/SmmCpuRendezvousLib.c
> > > new file mode 100644
> > > index 0000000000..3c5cd51d0c
> > > --- /dev/null
> > > +++
> b/UefiCpuPkg/Library/SmmCpuRendezvousLib/SmmCpuRendezvousLib.c
> > > @@ -0,0 +1,109 @@
> > > +/** @file
> > >
> > > +SMM CPU Rendezvous library header file.
> > >
> > > +
> > >
> > > +Copyright (c) 2021, Intel Corporation. All rights reserved.<BR>
> > >
> > > +SPDX-License-Identifier: BSD-2-Clause-Patent
> > >
> > > +
> > >
> > > +**/
> > >
> > > +
> > >
> > > +
> > >
> > > +#include <Base.h>
> > >
> > > +#include <Uefi.h>
> > >
> > > +#include <Library/BaseLib.h>
> > >
> > > +#include <Library/DebugLib.h>
> > >
> > > +#include <Library/PcdLib.h>
> > >
> > > +#include <Library/SmmServicesTableLib.h>
> > >
> > > +#include <Protocol/SmmCpuService.h>
> > >
> > > +#include <Library/SmmCpuRendezvousLib.h>
> > >
> > > +
> > >
> > > +STATIC EDKII_SMM_CPU_SERVICE_PROTOCOL  *mSmmCpuService =
> NULL;
> > >
> > > +
> > >
> > > +/**
> > >
> > > +  This routine wait for all AP processors to arrive in SMM.
> > >
> > > +
> > >
> > > +  @param  BlockingMode  Blocking mode or non-blocking mode.
> > >
> > > +
> > >
> > > +  @retval TRUE   All processors checked in to SMM
> > >
> > > +  @retval FALSE  Some processor not checked in to SMM
> > >
> > > +
> > >
> > > +**/
> > >
> > > +EFI_STATUS
> > >
> > > +EFIAPI
> > >
> > > +SmmWaitForAllProcessor (
> > >
> > > +  IN  BOOLEAN  BlockingMode
> > >
> > > +  )
> > >
> > > +{
> > >
> > > +  EFI_STATUS Status;
> > >
> > > +
> > >
> > > +  if (mSmmCpuService == NULL) {
> > >
> > > +    return TRUE;
> > >
> > > +  }
> > >
> > > +
> > >
> > > +  Status = mSmmCpuService->WaitForAllProcessor (
> > >
> > > +              mSmmCpuService,
> > >
> > > +              BlockingMode
> > >
> > > +              );
> > >
> > > +  return EFI_ERROR(Status) ? FALSE : TRUE;
> > >
> > > +}
> > >
> > > +
> > >
> > > +/**
> > >
> > > +  Register status code callback function only when Report Status
> > > + Code
> > protocol
> > >
> > > +  is installed.
> > >
> > > +
> > >
> > > +  @param Protocol       Points to the protocol's unique identifier.
> > >
> > > +  @param Interface      Points to the interface instance.
> > >
> > > +  @param Handle         The handle on which the interface was installed.
> > >
> > > +
> > >
> > > +  @retval EFI_SUCCESS   Notification runs successfully.
> > >
> > > +
> > >
> > > +**/
> > >
> > > +EFI_STATUS
> > >
> > > +EFIAPI
> > >
> > > +SmmCpuServiceProtocolNotify (
> > >
> > > +  IN CONST EFI_GUID        *Protocol,
> > >
> > > +  IN VOID                  *Interface,
> > >
> > > +  IN EFI_HANDLE            Handle
> > >
> > > +  )
> > >
> > > +{
> > >
> > > +  EFI_STATUS                   Status;
> > >
> > > +
> > >
> > > +  Status = gSmst->SmmLocateProtocol (
> > >
> > > +                    &gEdkiiSmmCpuServiceProtocolGuid,
> > >
> > > +                    NULL,
> > >
> > > +                    (VOID **) &mSmmCpuService
> > >
> > > +                    );
> > >
> > > +  ASSERT_EFI_ERROR (Status);
> > >
> > > +
> > >
> > > +  return EFI_SUCCESS;
> > >
> > > +}
> > >
> > > +
> > >
> > > +/**
> > >
> > > +  The constructor function
> > >
> > > +
> > >
> > > +  @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 constructor always returns EFI_SUCCESS.
> > >
> > > +
> > >
> > > +**/
> > >
> > > +EFI_STATUS
> > >
> > > +EFIAPI
> > >
> > > +SmmCpuRendezvousLibConstructor (
> > >
> > > +  IN EFI_HANDLE        ImageHandle,
> > >
> > > +  IN EFI_SYSTEM_TABLE  *SystemTable
> > >
> > > +  )
> > >
> > > +{
> > >
> > > +  EFI_STATUS  Status;
> > >
> > > +  VOID        *Registration;
> > >
> > > +
> > >
> > > +  Status = gSmst->SmmLocateProtocol
> > > + (&gEdkiiSmmCpuServiceProtocolGuid,
> > NULL, (VOID **) &mSmmCpuService);
> > >
> > > +  if (EFI_ERROR (Status)) {
> > >
> > > +    Status = gSmst->SmmRegisterProtocolNotify (
> > >
> > > +                &gEdkiiSmmCpuServiceProtocolGuid,
> > >
> > > +                SmmCpuServiceProtocolNotify,
> > >
> > > +                &Registration
> > >
> > > +                );
> > >
> > > +    ASSERT_EFI_ERROR (Status);
> > >
> > > +  }
> > >
> > > +  return EFI_SUCCESS;
> > >
> > > +}
> > > \ No newline at end of file
> > > diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/CpuService.c
> > b/UefiCpuPkg/PiSmmCpuDxeSmm/CpuService.c
> > > index 5d624f8e9e..34019c24ff 100644
> > > --- a/UefiCpuPkg/PiSmmCpuDxeSmm/CpuService.c
> > > +++ b/UefiCpuPkg/PiSmmCpuDxeSmm/CpuService.c
> > > @@ -20,6 +20,19 @@ EFI_SMM_CPU_SERVICE_PROTOCOL
> > mSmmCpuService = {
> > >    SmmRegisterExceptionHandler
> > >
> > >  };
> > >
> > >
> > >
> > > +//
> > >
> > > +// EDKII SMM CPU Service Protocol instance
> > >
> > > +//
> > >
> > > +EDKII_SMM_CPU_SERVICE_PROTOCOL  mEdkiiSmmCpuService = {
> > >
> > > +  SmmGetProcessorInfo,
> > >
> > > +  SmmSwitchBsp,
> > >
> > > +  SmmAddProcessor,
> > >
> > > +  SmmRemoveProcessor,
> > >
> > > +  SmmWhoAmI,
> > >
> > > +  SmmRegisterExceptionHandler,
> > >
> > > +  SmmWaitForAllProcessor
> > >
> > > +};
> > >
> > > +
> > >
> > >  /**
> > >
> > >    Gets processor information on the requested processor at the
> > > instant this
> > call is made.
> > >
> > >
> > >
> > > @@ -365,5 +378,57 @@ InitializeSmmCpuServices (
> > >                      &mSmmCpuService
> > >
> > >                      );
> > >
> > >    ASSERT_EFI_ERROR (Status);
> > >
> > > +
> > >
> > > +  Status = gSmst->SmmInstallProtocolInterface (
> > >
> > > +                    &Handle,
> > >
> > > +                    &gEdkiiSmmCpuServiceProtocolGuid,
> > >
> > > +                    EFI_NATIVE_INTERFACE,
> > >
> > > +                    &mEdkiiSmmCpuService
> > >
> > > +                    );
> > >
> > > +  ASSERT_EFI_ERROR (Status);
> > >
> > > +  return Status;
> > >
> > > +}
> > >
> > > +
> > >
> > > +/**
> > >
> > > +  Wait for all processors enterring SMM until all CPUs are already
> > synchronized or not.
> > >
> > > +
> > >
> > > +  @param  This                   A pointer to the
> > EDKII_SMM_CPU_SERVICE_PROTOCOL instance.
> > >
> > > +  @param  BlockingMode           Blocking mode or non-blocking mode.
> > >
> > > +
> > >
> > > +  @retval EFI_SUCCESS    All avaiable APs arrived.
> > >
> > > +  @retval EFI_TIMEOUT    Wait for all APs until timeout.
> > >
> > > +**/
> > >
> > > +EFI_STATUS
> > >
> > > +EFIAPI
> > >
> > > +SmmWaitForAllProcessor (
> > >
> > > +  IN  EDKII_SMM_CPU_SERVICE_PROTOCOL  *This,
> > >
> > > +  IN  BOOLEAN                          BlockingMode
> > >
> > > +  )
> > >
> > > +{
> > >
> > > +  EFI_STATUS                Status;
> > >
> > > +
> > >
> > > +  //
> > >
> > > +  // Return success immediately if all CPUs are already synchronized.
> > >
> > > +  //
> > >
> > > +  if (mSmmMpSyncData->AllApArrivedWithException) {
> > >
> > > +    Status = EFI_SUCCESS;
> > >
> > > +    goto ON_EXIT;
> > >
> > > +  }
> > >
> > > +
> > >
> > > +  if (!BlockingMode) {
> > >
> > > +    Status = EFI_TIMEOUT;
> > >
> > > +    goto ON_EXIT;
> > >
> > > +  }
> > >
> > > +
> > >
> > > +  //
> > >
> > > +  // There are some APs outside SMM, Wait for all avaiable APs to arrive.
> > >
> > > +  //
> > >
> > > +  SmmWaitForApArrival (BlockingMode);
> > >
> > > +  Status = mSmmMpSyncData->AllApArrivedWithException ?
> EFI_SUCCESS :
> > EFI_TIMEOUT;
> > >
> > > +
> > >
> > > +ON_EXIT:
> > >
> > > +  if (!mSmmMpSyncData->AllApArrivedWithException){
> > >
> > > +    DEBUG ((EFI_D_INFO, "EdkiiSmmWaitForAllApArrival: Timeout to
> > > + wait all
> > APs arrival\n"));
> > >
> > > +  }
> > >
> > >    return Status;
> > >
> > >  }
> > >
> > > diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c
> > b/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c
> > > index 882dee4fe2..9c7b16728a 100644
> > > --- a/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c
> > > +++ b/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c
> > > @@ -261,7 +261,7 @@ IsLmceSignaled (  **/
> > >
> > >  VOID
> > >
> > >  SmmWaitForApArrival (
> > >
> > > -  VOID
> > >
> > > +  IN  BOOLEAN  BlockingMode
> > >
> > >    )
> > >
> > >  {
> > >
> > >    UINT64   Timer;
> > >
> > > @@ -270,7 +270,14 @@ SmmWaitForApArrival (
> > >    BOOLEAN  LmceSignal;
> > >
> > >
> > >
> > >    ASSERT (*mSmmMpSyncData->Counter <= mNumberOfCpus);
> > >
> > > -
> > >
> > > +
> > >
> > > +  //
> > >
> > > +  // if block is False, do not wait and return immediately.
> > >
> > > +  //
> > >
> > > +  if (!BlockingMode){
> > >
> > > +    return;
> > >
> > > +  }
> > >
> > > +
> > >
> > >    LmceEn     = FALSE;
> > >
> > >    LmceSignal = FALSE;
> > >
> > >    if (mMachineCheckSupported) {
> > >
> > > @@ -511,7 +518,7 @@ BSPHandler (
> > >      //
> > >
> > >      // Wait for APs to arrive
> > >
> > >      //
> > >
> > > -    SmmWaitForApArrival ();
> > >
> > > +    SmmWaitForApArrival(TRUE);
> > >
> > >
> > >
> > >      //
> > >
> > >      // Lock the counter down and retrieve the number of APs
> > >
> > > @@ -1886,6 +1893,7 @@ InitializeMpSyncData (
> > >      *mSmmMpSyncData->Counter       = 0;
> > >
> > >      *mSmmMpSyncData->InsideSmm     = FALSE;
> > >
> > >      *mSmmMpSyncData->AllCpusInSync = FALSE;
> > >
> > > +    mSmmMpSyncData->AllApArrivedWithException = FALSE;
> > >
> > >
> > >
> > >      for (CpuIndex = 0; CpuIndex < gSmmCpuPrivate-
> > >SmmCoreEntryContext.NumberOfCpus; CpuIndex++) {
> > >
> > >        mSmmMpSyncData->CpuData[CpuIndex].Busy =
> > >
> > > diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/SyncTimer.c
> > b/UefiCpuPkg/PiSmmCpuDxeSmm/SyncTimer.c
> > > index 0c070c5736..844263f889 100644
> > > --- a/UefiCpuPkg/PiSmmCpuDxeSmm/SyncTimer.c
> > > +++ b/UefiCpuPkg/PiSmmCpuDxeSmm/SyncTimer.c
> > > @@ -8,7 +8,7 @@ SPDX-License-Identifier: BSD-2-Clause-Patent
> > >
> > >
> > >  #include "PiSmmCpuDxeSmm.h"
> > >
> > >
> > >
> > > -UINT64  mTimeoutTicker = 0;
> > >
> > > +UINT64   mTimeoutTicker = 0;
> > >
> > >  //
> > >
> > >  //  Number of counts in a roll-over cycle of the performance counter.
> > >
> > >  //
> > >
> > > diff --git a/UefiCpuPkg/Include/Library/SmmCpuRendezvousLib.h
> > b/UefiCpuPkg/Include/Library/SmmCpuRendezvousLib.h
> > > new file mode 100644
> > > index 0000000000..f245c3a1c9
> > > --- /dev/null
> > > +++ b/UefiCpuPkg/Include/Library/SmmCpuRendezvousLib.h
> > > @@ -0,0 +1,27 @@
> > > +/** @file
> > >
> > > +SMM CPU Rendezvous library header file.
> > >
> > > +
> > >
> > > +Copyright (c) 2021, Intel Corporation. All rights reserved.<BR>
> > >
> > > +SPDX-License-Identifier: BSD-2-Clause-Patent
> > >
> > > +
> > >
> > > +**/
> > >
> > > +
> > >
> > > +#ifndef _SMM_CPU_RENDEZVOUS_H_
> > >
> > > +#define _SMM_CPU_RENDEZVOUS_H_
> > >
> > > +
> > >
> > > +/**
> > >
> > > +  This routine wait for all AP processors to arrive in SMM.
> > >
> > > +
> > >
> > > +  @param  BlockingMode  Blocking mode or non-blocking mode.
> > >
> > > +
> > >
> > > +  @retval TRUE   All processors checked in to SMM
> > >
> > > +  @retval FALSE  Some processor not checked in to SMM
> > >
> > > +
> > >
> > > +**/
> > >
> > > +EFI_STATUS
> > >
> > > +EFIAPI
> > >
> > > +SmmWaitForAllProcessor (
> > >
> > > +  IN  BOOLEAN BlockingMode
> > >
> > > +  );
> > >
> > > +
> > >
> > > +#endif
> > >
> > > diff --git a/UefiCpuPkg/Include/Protocol/SmmCpuService.h
> > b/UefiCpuPkg/Include/Protocol/SmmCpuService.h
> > > index 952767afce..0ace5356a9 100644
> > > --- a/UefiCpuPkg/Include/Protocol/SmmCpuService.h
> > > +++ b/UefiCpuPkg/Include/Protocol/SmmCpuService.h
> > > @@ -200,4 +200,44 @@ struct _EFI_SMM_CPU_SERVICE_PROTOCOL {
> > >
> > >
> > >  extern EFI_GUID  gEfiSmmCpuServiceProtocolGuid;
> > >
> > >
> > >
> > > +//
> > >
> > > +//  EDKII_SMM_CPU_SERVICE_PROTOCOL extends the
> > EFI_SMM_CPU_SERVICE_PROTOCOL
> > >
> > > +//  with rendezvous service support.
> > >
> > > +//
> > >
> > > +#define EDKII_SMM_CPU_SERVICE_PROTOCOL_GUID \
> > >
> > > +  { \
> > >
> > > +    0xaa00d50b, 0x4911, 0x428f, {0xb9, 0x1a, 0xa5, 0x9d, 0xdb,
> > > + 0x13, 0xe2,
> > 0x4c} \
> > >
> > > +  }
> > >
> > > +
> > >
> > > +typedef struct _EDKII_SMM_CPU_SERVICE_PROTOCOL
> > EDKII_SMM_CPU_SERVICE_PROTOCOL;
> > >
> > > +
> > >
> > > +/**
> > >
> > > +  Wait for all APs to arrive SMM mode in given timeout constraint.
> > >
> > > +
> > >
> > > +  @param  This                  A pointer to the
> SMM_CPU_SERVICE_PROTOCOL
> > instance.
> > >
> > > +  @param  BlockingMode          Block or non-block mode.
> > >
> > > +
> > >
> > > +  @retval EFI_SUCCESS           All APs have arrived SMM mode except SMI
> > disabled APs.
> > >
> > > +  @retval EFI_TIMEOUT           There are APs not in SMM mode in given
> > timeout constraint.
> > >
> > > +
> > >
> > > +**/
> > >
> > > +typedef
> > >
> > > +EFI_STATUS
> > >
> > > +(EFIAPI *EDKII_WAIT_FOR_ALL_PROCESSOR) (
> > >
> > > +  IN  EDKII_SMM_CPU_SERVICE_PROTOCOL  *This,
> > >
> > > +  IN  BOOLEAN                         BlockingMode
> > >
> > > +  );
> > >
> > > +
> > >
> > > +struct _EDKII_SMM_CPU_SERVICE_PROTOCOL {
> > >
> > > +  EFI_SMM_GET_PROCESSOR_INFO          GetProcessorInfo;
> > >
> > > +  EFI_SMM_SWITCH_BSP                  SwitchBsp;
> > >
> > > +  EFI_SMM_ADD_PROCESSOR               AddProcessor;
> > >
> > > +  EFI_SMM_REMOVE_PROCESSOR            RemoveProcessor;
> > >
> > > +  EFI_SMM_WHOAMI                      WhoAmI;
> > >
> > > +  EFI_SMM_REGISTER_EXCEPTION_HANDLER  RegisterExceptionHandler;
> > >
> > > +  EDKII_WAIT_FOR_ALL_PROCESSOR        WaitForAllProcessor;
> > >
> > > +};
> > >
> > > +
> > >
> > > +extern EFI_GUID gEdkiiSmmCpuServiceProtocolGuid;
> > >
> > > +
> > >
> > >  #endif
> > >
> > > diff --git
> > a/UefiCpuPkg/Library/SmmCpuRendezvousLib/SmmCpuRendezvousLib.inf
> > >
> b/UefiCpuPkg/Library/SmmCpuRendezvousLib/SmmCpuRendezvousLib.inf
> > > new file mode 100644
> > > index 0000000000..aff77c5a18
> > > --- /dev/null
> > > +++
> b/UefiCpuPkg/Library/SmmCpuRendezvousLib/SmmCpuRendezvousLib.inf
> > > @@ -0,0 +1,32 @@
> > > +## @file
> > >
> > > +# Component description file for CPU SMM Rendezvous check library
> > >
> > > +##
> > >
> > > +
> > >
> > > +[Defines]
> > >
> > > +  INF_VERSION                    = 0x00010005
> > >
> > > +  BASE_NAME                      = SmmCpuRendezvousLib
> > >
> > > +  FILE_GUID                      = 1509Bb36-9Ba4-438B-B195-Ac5914Db14E2
> > >
> > > +  MODULE_TYPE                    = DXE_SMM_DRIVER
> > >
> > > +  VERSION_STRING                 = 1.0
> > >
> > > +  LIBRARY_CLASS                  = SmmCpuRendezvousLib
> > >
> > > +  CONSTRUCTOR                    = SmmCpuRendezvousLibConstructor
> > >
> > > +
> > >
> > > +[Sources]
> > >
> > > +  SmmCpuRendezvousLib.c
> > >
> > > +
> > >
> > > +[Packages]
> > >
> > > +  MdePkg/MdePkg.dec
> > >
> > > +  UefiCpuPkg/UefiCpuPkg.dec
> > >
> > > +
> > >
> > > +[LibraryClasses]
> > >
> > > +  BaseLib
> > >
> > > +  DebugLib
> > >
> > > +  PcdLib
> > >
> > > +  SmmServicesTableLib
> > >
> > > +
> > >
> > > +[Pcd]
> > >
> > > +  gUefiCpuPkgTokenSpaceGuid.PcdCpuSmmApSyncTimeout                 ##
> > CONSUMES
> > >
> > > +
> > >
> > > +[Protocols]
> > >
> > > +  gEdkiiSmmCpuServiceProtocolGuid
> > >
> > > +
> > >
> > > diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.h
> > b/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.h
> > > index 26d07c5b5e..c6f31ace77 100644
> > > --- a/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.h
> > > +++ b/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.h
> > > @@ -428,6 +428,7 @@ typedef struct {
> > >    volatile SMM_CPU_SYNC_MODE    EffectiveSyncMode;
> > >
> > >    volatile BOOLEAN              SwitchBsp;
> > >
> > >    volatile BOOLEAN              *CandidateBsp;
> > >
> > > +  volatile BOOLEAN              AllApArrivedWithException;
> > >
> > >    EFI_AP_PROCEDURE              StartupProcedure;
> > >
> > >    VOID                          *StartupProcArgs;
> > >
> > >  } SMM_DISPATCHER_MP_SYNC_DATA;
> > >
> > > @@ -1488,4 +1489,31 @@ IsRestrictedMemoryAccess (
> > >    VOID
> > >
> > >    );
> > >
> > >
> > >
> > > +/**
> > >
> > > +  Choose blocking or non-blocking mode to Wait for all APs
> > >
> > > +
> > >
> > > +  @param  This                  A pointer to the
> SMM_CPU_SERVICE_PROTOCOL
> > instance.
> > >
> > > +  @param  BlockingMode          Blocking or non-blocking mode
> > >
> > > +
> > >
> > > +  @retval EFI_SUCCESS           All APs have arrived SMM mode except SMI
> > disabled APs.
> > >
> > > +  @retval EFI_TIMEOUT           There are APs not in SMM mode in given
> > timeout constraint.
> > >
> > > +
> > >
> > > +**/
> > >
> > > +EFI_STATUS
> > >
> > > +EFIAPI
> > >
> > > +SmmWaitForAllProcessor (
> > >
> > > +  IN  EDKII_SMM_CPU_SERVICE_PROTOCOL  *This,
> > >
> > > +  IN  BOOLEAN                          BlockingMode
> > >
> > > +  );
> > >
> > > +
> > >
> > > +/**
> > >
> > > +  Choose blocking or non-blocking mode to wait for all APs. True
> > > + for Blocking
> > and false for not.
> > >
> > > +  Insure when this function returns, no AP will execute normal mode
> > > + code
> > before entering SMM, except SMI disabled APs.
> > >
> > > +
> > >
> > > +**/
> > >
> > > +VOID
> > >
> > > +SmmWaitForApArrival (
> > >
> > > +  IN  BOOLEAN  BlockingMode
> > >
> > > +  );
> > >
> > > +
> > >
> > >  #endif
> > >
> > > diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.inf
> > b/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.inf
> > > index 0e88071c70..1af7280d18 100644
> > > --- a/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.inf
> > > +++ b/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.inf
> > > @@ -107,7 +107,8 @@
> > >    gEfiSmmReadyToLockProtocolGuid           ## NOTIFY
> > >
> > >    gEfiSmmCpuServiceProtocolGuid            ## PRODUCES
> > >
> > >    gEdkiiSmmMemoryAttributeProtocolGuid     ## PRODUCES
> > >
> > > -  gEfiMmMpProtocolGuid                    ## PRODUCES
> > >
> > > +  gEfiMmMpProtocolGuid                     ## PRODUCES
> > >
> > > +  gEdkiiSmmCpuServiceProtocolGuid          ## PRODUCES
> > >
> > >
> > >
> > >  [Guids]
> > >
> > >    gEfiAcpiVariableGuid                     ## SOMETIMES_CONSUMES ## HOB # it
> is
> > used for S3 boot.
> > >
> > > diff --git a/UefiCpuPkg/UefiCpuPkg.dec b/UefiCpuPkg/UefiCpuPkg.dec
> > > index 7de66fde67..c170e7d75d 100644
> > > --- a/UefiCpuPkg/UefiCpuPkg.dec
> > > +++ b/UefiCpuPkg/UefiCpuPkg.dec
> > > @@ -77,7 +77,8 @@
> > >
> > >
> > >  [Protocols]
> > >
> > >    ## Include/Protocol/SmmCpuService.h
> > >
> > > -  gEfiSmmCpuServiceProtocolGuid  = { 0x1d202cab, 0xc8ab, 0x4d5c, {
> > > 0x94,
> > 0xf7, 0x3c, 0xfc, 0xc0, 0xd3, 0xd3, 0x35 }}
> > >
> > > +  gEfiSmmCpuServiceProtocolGuid   = { 0x1d202cab, 0xc8ab, 0x4d5c,
> { 0x94,
> > 0xf7, 0x3c, 0xfc, 0xc0, 0xd3, 0xd3, 0x35 }}
> > >
> > > +  gEdkiiSmmCpuServiceProtocolGuid = { 0xaa00d50b, 0x4911, 0x428f, {
> > > + 0xb9,
> > 0x1a, 0xa5, 0x9d, 0xdb, 0x13, 0xe2, 0x4c }}
> > >
> > >
> > >
> > >    ## Include/Protocol/SmMonitorInit.h
> > >
> > >    gEfiSmMonitorInitProtocolGuid  = { 0x228f344d, 0xb3de, 0x43bb, {
> > > 0xa4,
> > 0xd7, 0xea, 0x20, 0xb, 0x1b, 0x14, 0x82 }}
> > >
> > > @@ -304,7 +305,7 @@
> > >    #   0x00  - Traditional CPU synchronization method.<BR>
> > >
> > >    #   0x01  - Relaxed CPU synchronization method.<BR>
> > >
> > >    # @Prompt SMM CPU Synchronization Method.
> > >
> > > -
> >
> gUefiCpuPkgTokenSpaceGuid.PcdCpuSmmSyncMode|0x00|UINT8|0x60000
> 014
> > >
> > > +
> >
> gUefiCpuPkgTokenSpaceGuid.PcdCpuSmmSyncMode|0x01|UINT8|0x60000
> 014
> > >
> > >
> > >
> > >    ## Specifies the On-demand clock modulation duty cycle when ACPI
> > > feature
> > is enabled.
> > >
> > >    # @Prompt The encoded values for target duty cycle modulation.
> > >
> > > --
> > > 2.26.2.windows.1
> > >
> > >
> > >
> > >
> > >
> >
> >
> >
> > 
> >