Re: [PATCH v2 1/4] UefiCpuPkg/PiSmmCpuDxeSmm: dynamic PcdCpuSmmApSyncTimeout, PcdCpuSmmSyncMode

[Laszlo Ersek <lersek@redhat.com>]

On 11/22/16 08:20, Fan, Jeff wrote:
> Reviewed-by: Jeff Fan <jeff.fan@intel.com>

Thank Jeff!

I committed this patch in isolation (b43dd22981b7), because I think it
has value without the OvmfPkg changes too. Plus, I think the OvmfPkg
changes might take longer to get into the tree, and I wouldn't like
PiSmmCpuDxeSmm to diverge in the meantime.

Thanks!
Laszlo

> -----Original Message-----
> From: Laszlo Ersek [mailto:lersek@redhat.com] 
> Sent: Friday, November 18, 2016 9:53 PM
> To: edk2-devel-01
> Cc: Fan, Jeff; Justen, Jordan L; Kinney, Michael D; Paolo Bonzini
> Subject: [PATCH v2 1/4] UefiCpuPkg/PiSmmCpuDxeSmm: dynamic PcdCpuSmmApSyncTimeout, PcdCpuSmmSyncMode
> 
> Move the declaration of these PCDs from the
> 
>   [PcdsFixedAtBuild, PcdsPatchableInModule]
> 
> section of "UefiCpuPkg/UefiCpuPkg.dec" to the
> 
>   [PcdsFixedAtBuild, PcdsPatchableInModule, PcdsDynamic, PcdsDynamicEx]
> 
> section. Their types, default values, and token values remain unchanged.
> 
> Only UefiCpuPkg/PiSmmCpuDxeSmm consumes these PCDs, specifically on the call stack of its entry point function, and it turns them into static or dynamically allocated data in SMRAM:
> 
>   PiCpuSmmEntry()                            [PiSmmCpuDxeSmm.c]
>     InitializeSmmTimer()                     [SyncTimer.c]
>       PcdCpuSmmApSyncTimeout
>       -> mTimeoutTicker
>     InitializeMpServiceData()                [MpService.c]
>       InitializeMpSyncData()                 [MpService.c]
>         PcdCpuSmmSyncMode
>         -> mSmmMpSyncData->EffectiveSyncMode
> 
> However, there's another call path to fetching "PcdCpuSmmSyncMode", namely
> 
>   SmmInitHandler()                           [PiSmmCpuDxeSmm.c]
>     InitializeMpSyncData()                   [MpService.c]
>       PcdCpuSmmSyncMode
>       -> mSmmMpSyncData->EffectiveSyncMode
> 
> and this path is exercised during S3 resume (as stated by the comment in
> SmmInitHandler() too, "Initialize private data during S3 resume").
> 
> While we can call the PCD protocol (via PcdLib) for fetching dynamic PCDs in the entry point function, we cannot do that at S3 resume. Therefore pre-fetch PcdCpuSmmSyncMode into a new global variable (which lives in
> SMRAM) in InitializeMpServiceData(), just before calling InitializeMpSyncData(). This way InitializeMpSyncData() can retrieve the stashed PCD value from SMRAM, regardless of the boot mode.
> 
> Cc: Jeff Fan <jeff.fan@intel.com>
> Cc: Jordan Justen <jordan.l.justen@intel.com>
> Cc: Michael Kinney <michael.d.kinney@intel.com>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=230
> Contributed-under: TianoCore Contribution Agreement 1.0
> Signed-off-by: Laszlo Ersek <lersek@redhat.com>
> ---
> 
> Notes:
>     v2:
>     - new in v2
> 
>  UefiCpuPkg/UefiCpuPkg.dec             | 20 ++++++++++----------
>  UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c |  4 +++-
>  2 files changed, 13 insertions(+), 11 deletions(-)
> 
> diff --git a/UefiCpuPkg/UefiCpuPkg.dec b/UefiCpuPkg/UefiCpuPkg.dec index 89779c447d50..ca560398bbef 100644
> --- a/UefiCpuPkg/UefiCpuPkg.dec
> +++ b/UefiCpuPkg/UefiCpuPkg.dec
> @@ -156,10 +156,6 @@ [PcdsFixedAtBuild, PcdsPatchableInModule]
>    # @Prompt Processor stack size in SMM.
>    gUefiCpuPkgTokenSpaceGuid.PcdCpuSmmStackSize|0x2000|UINT32|0x32132105
>  
> -  ## Specifies timeout value in microseconds for the BSP in SMM to wait for all APs to come into SMM.
> -  # @Prompt AP synchronization timeout value in SMM.
> -  gUefiCpuPkgTokenSpaceGuid.PcdCpuSmmApSyncTimeout|1000000|UINT64|0x32132104
> -
>    ## Indicates if SMM Code Access Check is enabled.
>    #  If enabled, the SMM handler cannot execute the code outside SMM regions.
>    #  This PCD is suggested to TRUE in production image.<BR><BR> @@ -168,12 +164,6 @@ [PcdsFixedAtBuild, PcdsPatchableInModule]
>    # @Prompt SMM Code Access Check.
>    gUefiCpuPkgTokenSpaceGuid.PcdCpuSmmCodeAccessCheckEnable|TRUE|BOOLEAN|0x60000013
>  
> -  ## Indicates the CPU synchronization method used when processing an SMI.
> -  #   0x00  - Traditional CPU synchronization method.<BR>
> -  #   0x01  - Relaxed CPU synchronization method.<BR>
> -  # @Prompt SMM CPU Synchronization Method.
> -  gUefiCpuPkgTokenSpaceGuid.PcdCpuSmmSyncMode|0x00|UINT8|0x60000014
> -
>    ## Specifies the number of variable MTRRs reserved for OS use. The default number of
>    #  MTRRs reserved for OS use is 2.
>    # @Prompt Number of reserved variable MTRRs.
> @@ -214,6 +204,16 @@ [PcdsFixedAtBuild, PcdsPatchableInModule, PcdsDynamic, PcdsDynamicEx]
>    # @Prompt Use static page table for all memory in SMM.
>    gUefiCpuPkgTokenSpaceGuid.PcdCpuSmmStaticPageTable|TRUE|BOOLEAN|0x3213210D
>  
> +  ## Specifies timeout value in microseconds for the BSP in SMM to wait for all APs to come into SMM.
> +  # @Prompt AP synchronization timeout value in SMM.
> +  
> + gUefiCpuPkgTokenSpaceGuid.PcdCpuSmmApSyncTimeout|1000000|UINT64|0x3213
> + 2104
> +
> +  ## Indicates the CPU synchronization method used when processing an SMI.
> +  #   0x00  - Traditional CPU synchronization method.<BR>
> +  #   0x01  - Relaxed CPU synchronization method.<BR>
> +  # @Prompt SMM CPU Synchronization Method.
> +  gUefiCpuPkgTokenSpaceGuid.PcdCpuSmmSyncMode|0x00|UINT8|0x60000014
> +
>  [PcdsDynamic, PcdsDynamicEx]
>    ## Contains the pointer to a CPU S3 data buffer of structure ACPI_CPU_DATA.
>    # @Prompt The pointer to a CPU S3 data buffer.
> diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c b/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c
> index 9b8db90ff6ed..cfbf59e8f2ca 100644
> --- a/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c
> +++ b/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c
> @@ -24,6 +24,7 @@ UINTN                                       mSmmMpSyncDataSize;
>  SMM_CPU_SEMAPHORES                          mSmmCpuSemaphores;
>  UINTN                                       mSemaphoreSize;
>  SPIN_LOCK                                   *mPFLock = NULL;
> +SMM_CPU_SYNC_MODE                           mCpuSmmSyncMode;
>  
>  /**
>    Performs an atomic compare exchange operation to get semaphore.
> @@ -1338,7 +1339,7 @@ InitializeMpSyncData (
>        //
>        mSmmMpSyncData->BspIndex = (UINT32)-1;
>      }
> -    mSmmMpSyncData->EffectiveSyncMode = (SMM_CPU_SYNC_MODE) PcdGet8 (PcdCpuSmmSyncMode);
> +    mSmmMpSyncData->EffectiveSyncMode = mCpuSmmSyncMode;
>  
>      mSmmMpSyncData->Counter       = mSmmCpuSemaphores.SemaphoreGlobal.Counter;
>      mSmmMpSyncData->InsideSmm     = mSmmCpuSemaphores.SemaphoreGlobal.InsideSmm;
> @@ -1392,6 +1393,7 @@ InitializeMpServiceData (
>                         (sizeof (SMM_CPU_DATA_BLOCK) + sizeof (BOOLEAN)) * gSmmCpuPrivate->SmmCoreEntryContext.NumberOfCpus;
>    mSmmMpSyncData = (SMM_DISPATCHER_MP_SYNC_DATA*) AllocatePages (EFI_SIZE_TO_PAGES (mSmmMpSyncDataSize));
>    ASSERT (mSmmMpSyncData != NULL);
> +  mCpuSmmSyncMode = (SMM_CPU_SYNC_MODE)PcdGet8 (PcdCpuSmmSyncMode);
>    InitializeMpSyncData ();
>  
>    //
> --
> 2.9.2
> 
> 
> _______________________________________________
> edk2-devel mailing list
> edk2-devel@lists.01.org
> https://lists.01.org/mailman/listinfo/edk2-devel
>