Re: [Patch 2/3] UefiCpuPkg/MpInitLib: Use BSP uCode for APs if possible.

[Laszlo Ersek <lersek@redhat.com>]

On 07/11/18 13:07, Eric Dong wrote:
> Search uCode costs much time, if AP has same processor type
> with BSP, AP can use BSP saved uCode info to get better performance.
> 
> This change enables this solution.
> 
> Cc: Laszlo Ersek <lersek@redhat.com>
> Cc: Ruiyu Ni <ruiyu.ni@intel.com>
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Eric Dong <eric.dong@intel.com>
> ---
>  UefiCpuPkg/Library/MpInitLib/Microcode.c | 34 +++++++++++++++++++++++++++++---
>  UefiCpuPkg/Library/MpInitLib/MpLib.c     |  4 ++--
>  UefiCpuPkg/Library/MpInitLib/MpLib.h     | 11 +++++++++--
>  3 files changed, 42 insertions(+), 7 deletions(-)
> 
> diff --git a/UefiCpuPkg/Library/MpInitLib/Microcode.c b/UefiCpuPkg/Library/MpInitLib/Microcode.c
> index e47f9f4f8f..351975e2a2 100644
> --- a/UefiCpuPkg/Library/MpInitLib/Microcode.c
> +++ b/UefiCpuPkg/Library/MpInitLib/Microcode.c
> @@ -35,11 +35,13 @@ GetCurrentMicrocodeSignature (
>  /**
>    Detect whether specified processor can find matching microcode patch and load it.
>  
> -  @param[in]  CpuMpData  The pointer to CPU MP Data structure.
> +  @param[in]  CpuMpData    The pointer to CPU MP Data structure.
> +  @param[in]  IsBspCallIn  Indicate whether the caller is BSP or not.
>  **/
>  VOID
>  MicrocodeDetect (
> -  IN CPU_MP_DATA             *CpuMpData
> +  IN CPU_MP_DATA             *CpuMpData,
> +  IN BOOLEAN                 IsBspCallIn
>    )
>  {
>    UINT32                                  ExtendedTableLength;
> @@ -58,6 +60,7 @@ MicrocodeDetect (
>    BOOLEAN                                 CorrectMicrocode;
>    VOID                                    *MicrocodeData;
>    MSR_IA32_PLATFORM_ID_REGISTER           PlatformIdMsr;
> +  UINT32                                  ProcessorFlags;
>  
>    if (CpuMpData->MicrocodePatchRegionSize == 0) {
>      //
> @@ -67,7 +70,7 @@ MicrocodeDetect (
>    }
>  
>    CurrentRevision = GetCurrentMicrocodeSignature ();
> -  if (CurrentRevision != 0) {
> +  if (CurrentRevision != 0 && !IsBspCallIn) {
>      //
>      // Skip loading microcode if it has been loaded successfully
>      //
> @@ -87,6 +90,19 @@ MicrocodeDetect (
>    PlatformIdMsr.Uint64 = AsmReadMsr64 (MSR_IA32_PLATFORM_ID);
>    PlatformId = (UINT8) PlatformIdMsr.Bits.PlatformId;
>  
> +  //
> +  // Check whether AP has same processor with BSP.
> +  // If yes, direct use microcode info saved by BSP.
> +  //
> +  if (!IsBspCallIn) {
> +    if ((CpuMpData->ProcessorSignature == Eax.Uint32) &&
> +        (CpuMpData->ProcessorFlags & (1 << PlatformId)) != 0) {

Here I have only one comment. (The reason for that is that, on OVMF,
MicrocodePatchRegionSize is zero, so MicrocodeDetect() will exit
immediately, on both the APs and the BSP.)

My comment is that the expression

  (1 << PlatformId)

may invoke undefined behavior (and rightfully trigger build breakage
with e.g. clang) if PlatformId is larger than 31.

Now, I do see the comment

  //
  // The index of platform information resides in bits 50:52 of MSR IA32_PLATFORM_ID
  //

so I wanted to suggest adding:

  ASSERT (PlatformId < 8)?

but then I saw that the same left-shift was already used in two other
places.

So, with or without the ASSERT:

Acked-by: Laszlo Ersek <lersek@redhat.com>

Thanks
Laszlo



> +        MicrocodeData = (VOID *)(UINTN) CpuMpData->MicrocodeDataAddress;
> +        LatestRevision = CpuMpData->MicrocodeRevision;
> +        goto Done;
> +    }
> +  }
> +
>    LatestRevision = 0;
>    MicrocodeData  = NULL;
>    MicrocodeEnd = (UINTN) (CpuMpData->MicrocodePatchAddress + CpuMpData->MicrocodePatchRegionSize);
> @@ -117,6 +133,7 @@ MicrocodeDetect (
>          }
>          if (CheckSum32 == 0) {
>            CorrectMicrocode = TRUE;
> +          ProcessorFlags = MicrocodeEntryPoint->ProcessorFlags;
>          }
>        } else if ((MicrocodeEntryPoint->DataSize != 0) &&
>                   (MicrocodeEntryPoint->UpdateRevision > LatestRevision)) {
> @@ -151,6 +168,7 @@ MicrocodeDetect (
>                      // Find one
>                      //
>                      CorrectMicrocode = TRUE;
> +                    ProcessorFlags = ExtendedTable->ProcessorFlag;
>                      break;
>                    }
>                  }
> @@ -188,6 +206,7 @@ MicrocodeDetect (
>      MicrocodeEntryPoint = (CPU_MICROCODE_HEADER *) (((UINTN) MicrocodeEntryPoint) + TotalSize);
>    } while (((UINTN) MicrocodeEntryPoint < MicrocodeEnd));
>  
> +Done:
>    if (LatestRevision > CurrentRevision) {
>      //
>      // BIOS only authenticate updates that contain a numerically larger revision
> @@ -211,4 +230,13 @@ MicrocodeDetect (
>        ReleaseSpinLock(&CpuMpData->MpLock);
>      }
>    }
> +
> +  if (IsBspCallIn && (LatestRevision != 0)) {
> +    CpuMpData->ProcessorSignature = Eax.Uint32;
> +    CpuMpData->ProcessorFlags = ProcessorFlags;
> +    CpuMpData->MicrocodeDataAddress = (UINTN) MicrocodeData;
> +    CpuMpData->MicrocodeRevision = LatestRevision;
> +    DEBUG ((DEBUG_INFO, "BSP Microcode:: signature [0x%08x], ProcessorFlags [0x%08x], \
> +       MicroData [0x%08x], Revision [0x%08x]\n", Eax.Uint32, ProcessorFlags, (UINTN) MicrocodeData, LatestRevision));
> +  }
>  }
> diff --git a/UefiCpuPkg/Library/MpInitLib/MpLib.c b/UefiCpuPkg/Library/MpInitLib/MpLib.c
> index 8b458a4a3a..9179f9ae6d 100644
> --- a/UefiCpuPkg/Library/MpInitLib/MpLib.c
> +++ b/UefiCpuPkg/Library/MpInitLib/MpLib.c
> @@ -410,7 +410,7 @@ ApInitializeSync (
>    //
>    // Load microcode on AP
>    //
> -  MicrocodeDetect (CpuMpData);
> +  MicrocodeDetect (CpuMpData, FALSE);
>    //
>    // Sync BSP's MTRR table to AP
>    //
> @@ -1601,7 +1601,7 @@ MpInitLibInitialize (
>    //
>    // Load Microcode on BSP
>    //
> -  MicrocodeDetect (CpuMpData);
> +  MicrocodeDetect (CpuMpData, TRUE);
>    //
>    // Store BSP's MTRR setting
>    //
> diff --git a/UefiCpuPkg/Library/MpInitLib/MpLib.h b/UefiCpuPkg/Library/MpInitLib/MpLib.h
> index 73e689d969..d897497b77 100644
> --- a/UefiCpuPkg/Library/MpInitLib/MpLib.h
> +++ b/UefiCpuPkg/Library/MpInitLib/MpLib.h
> @@ -246,6 +246,11 @@ struct _CPU_MP_DATA {
>    BOOLEAN                        TimerInterruptState;
>    UINT64                         MicrocodePatchAddress;
>    UINT64                         MicrocodePatchRegionSize;
> +
> +  UINT32                         ProcessorSignature;
> +  UINT32                         ProcessorFlags;
> +  UINT64                         MicrocodeDataAddress;
> +  UINT32                         MicrocodeRevision;
>  };
>  
>  extern EFI_GUID mCpuInitMpLibHobGuid;
> @@ -547,11 +552,13 @@ CheckAndUpdateApsStatus (
>  /**
>    Detect whether specified processor can find matching microcode patch and load it.
>  
> -  @param[in]  CpuMpData  The pointer to CPU MP Data structure.
> +  @param[in]  CpuMpData    The pointer to CPU MP Data structure.
> +  @param[in]  IsBspCallIn  Indicate whether the caller is BSP or not.
>  **/
>  VOID
>  MicrocodeDetect (
> -  IN CPU_MP_DATA             *CpuMpData
> +  IN CPU_MP_DATA             *CpuMpData,
> +  IN BOOLEAN                 IsBspCallIn
>    );
>  
>  /**
>