[edk2-devel] [PATCH] UefiCpuPkg/PiSmmCpu: Don't allocate Token for SmmStartupThisAp

[Ni, Ray]

+ Bug submitter Crystal Lee.

> -----Original Message-----
> From: devel at edk2.groups.io <devel at edk2.groups.io> On Behalf Of Ni, Ray
> Sent: Monday, March 8, 2021 10:17 AM
> To: devel at edk2.groups.io
> Cc: Dong, Eric <eric.dong at intel.com>; Laszlo Ersek <lersek at redhat.com>;
> Kumar, Rahul1 <rahul1.kumar at intel.com>
> Subject: [edk2-devel] [PATCH] UefiCpuPkg/PiSmmCpu: Don't allocate Token
> for SmmStartupThisAp
> 
> REF: https://bugzilla.tianocore.org/show_bug.cgi?id=3199
> 
> When Token points to mSmmStartupThisApToken, this routine is called
> from SmmStartupThisAp() in non-blocking mode due to
> PcdCpuSmmBlockStartupThisAp == FALSE.
> 
> In this case, caller wants to startup AP procedure in non-blocking
> mode and cannot get the completion status from the Token because there
> is no way to return the Token to caller from SmmStartupThisAp().
> Caller needs to use its specific way to query the completion status.
> 
> There is no need to allocate a token for such case so the 2 overheads
> can be avoided:
> 1. Call AllocateTokenBuffer() when there is no free token.
> 2. Get a free token from the token buffer.
> 
> Signed-off-by: Ray Ni <ray.ni at intel.com>
> Cc: Eric Dong <eric.dong at intel.com>
> Cc: Laszlo Ersek <lersek at redhat.com>
> Cc: Rahul Kumar <rahul1.kumar at intel.com>
> ---
>  UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c | 27
> ++++++++++++++++++++-------
>  1 file changed, 20 insertions(+), 7 deletions(-)
> 
> diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c
> b/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c
> index 6227b2428a..efb89832ca 100644
> --- a/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c
> +++ b/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c
> @@ -1,7 +1,7 @@
>  /** @file
> 
>  SMM MP service implementation
> 
> 
> 
> -Copyright (c) 2009 - 2020, Intel Corporation. All rights reserved.<BR>
> 
> +Copyright (c) 2009 - 2021, Intel Corporation. All rights reserved.<BR>
> 
>  Copyright (c) 2017, AMD Incorporated. All rights reserved.<BR>
> 
> 
> 
>  SPDX-License-Identifier: BSD-2-Clause-Patent
> 
> @@ -22,6 +22,7 @@ UINTN                                       mSemaphoreSize;
>  SPIN_LOCK                                   *mPFLock = NULL;
> 
>  SMM_CPU_SYNC_MODE                           mCpuSmmSyncMode;
> 
>  BOOLEAN                                     mMachineCheckSupported = FALSE;
> 
> +MM_COMPLETION                               mSmmStartupThisApToken;
> 
> 
> 
>  extern UINTN mSmmShadowStackSize;
> 
> 
> 
> @@ -1240,9 +1241,23 @@ InternalSmmStartupThisAp (
>    mSmmMpSyncData->CpuData[CpuIndex].Procedure = Procedure;
> 
>    mSmmMpSyncData->CpuData[CpuIndex].Parameter = ProcArguments;
> 
>    if (Token != NULL) {
> 
> -    ProcToken= GetFreeToken (1);
> 
> -    mSmmMpSyncData->CpuData[CpuIndex].Token = ProcToken;
> 
> -    *Token = (MM_COMPLETION)ProcToken->SpinLock;
> 
> +    if (Token != &mSmmStartupThisApToken) {
> 
> +      //
> 
> +      // When Token points to mSmmStartupThisApToken, this routine is
> called
> 
> +      // from SmmStartupThisAp() in non-blocking mode
> (PcdCpuSmmBlockStartupThisAp == FALSE).
> 
> +      //
> 
> +      // In this case, caller wants to startup AP procedure in non-blocking
> 
> +      // mode and cannot get the completion status from the Token because
> there
> 
> +      // is no way to return the Token to caller from SmmStartupThisAp().
> 
> +      // Caller needs to use its implementation specific way to query the
> completion status.
> 
> +      //
> 
> +      // There is no need to allocate a token for such case so the overhead of
> SMRAM and
> 
> +      // the allocation operation can be avoided.
> 
> +      //
> 
> +      ProcToken= GetFreeToken (1);
> 
> +      mSmmMpSyncData->CpuData[CpuIndex].Token = ProcToken;
> 
> +      *Token = (MM_COMPLETION)ProcToken->SpinLock;
> 
> +    }
> 
>    }
> 
>    mSmmMpSyncData->CpuData[CpuIndex].Status    = CpuStatus;
> 
>    if (mSmmMpSyncData->CpuData[CpuIndex].Status != NULL) {
> 
> @@ -1474,8 +1489,6 @@ SmmStartupThisAp (
>    IN OUT  VOID                      *ProcArguments OPTIONAL
> 
>    )
> 
>  {
> 
> -  MM_COMPLETION               Token;
> 
> -
> 
>    gSmmCpuPrivate->ApWrapperFunc[CpuIndex].Procedure = Procedure;
> 
>    gSmmCpuPrivate->ApWrapperFunc[CpuIndex].ProcedureArgument =
> ProcArguments;
> 
> 
> 
> @@ -1486,7 +1499,7 @@ SmmStartupThisAp (
>      ProcedureWrapper,
> 
>      CpuIndex,
> 
>      &gSmmCpuPrivate->ApWrapperFunc[CpuIndex],
> 
> -    FeaturePcdGet (PcdCpuSmmBlockStartupThisAp) ? NULL : &Token,
> 
> +    FeaturePcdGet (PcdCpuSmmBlockStartupThisAp) ? NULL :
> &mSmmStartupThisApToken,
> 
>      0,
> 
>      NULL
> 
>      );
> 
> --
> 2.27.0.windows.1
> 
> 
> 
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