Re: [Patch] UefiCpuPkg/MpInitLib: Avoid copy twice.

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

On 07/31/19 10:01, Eric Dong wrote:
> REF: https://bugzilla.tianocore.org/show_bug.cgi?id=1982
> 
> MpInitLibInitialize in MpLib.c will be invoked on both PEI and DXE
> CPU code, MicrocodeDetect would be performed twice and copy
> Microcode from flash to memory twice as well, which consider as
> duplicate work to lead longer boot time.
> This patch just use microcode memory copied in PEI phase if exist.
> 
> Signed-off-by: Eric Dong <eric.dong@intel.com>
> Cc: Ray Ni <ray.ni@intel.com>
> Cc: Laszlo Ersek <lersek@redhat.com>
> ---
>  UefiCpuPkg/Library/MpInitLib/MpLib.c | 62 +++++++++++++++-------------
>  1 file changed, 33 insertions(+), 29 deletions(-)
> 
> diff --git a/UefiCpuPkg/Library/MpInitLib/MpLib.c b/UefiCpuPkg/Library/MpInitLib/MpLib.c
> index 572495ec36..a1ad665564 100644
> --- a/UefiCpuPkg/Library/MpInitLib/MpLib.c
> +++ b/UefiCpuPkg/Library/MpInitLib/MpLib.c
> @@ -1607,38 +1607,42 @@ MpInitLibInitialize (
>    CpuMpData->SwitchBspFlag    = FALSE;
>    CpuMpData->CpuData          = (CPU_AP_DATA *) (CpuMpData + 1);
>    CpuMpData->CpuInfoInHob     = (UINT64) (UINTN) (CpuMpData->CpuData + MaxLogicalProcessorNumber);
> -  CpuMpData->MicrocodePatchRegionSize = PcdGet64 (PcdCpuMicrocodePatchRegionSize);
> -  //
> -  // If platform has more than one CPU, relocate microcode to memory to reduce
> -  // loading microcode time.
> -  //
> -  MicrocodePatchInRam = NULL;
> -  if (MaxLogicalProcessorNumber > 1) {
> -    MicrocodePatchInRam = AllocatePages (
> -                            EFI_SIZE_TO_PAGES (
> -                              (UINTN)CpuMpData->MicrocodePatchRegionSize
> -                              )
> -                            );
> -  }
> -  if (MicrocodePatchInRam == NULL) {
> -    //
> -    // there is only one processor, or no microcode patch is available, or
> -    // memory allocation failed
> -    //
> -    CpuMpData->MicrocodePatchAddress = PcdGet64 (PcdCpuMicrocodePatchAddress);
> -  } else {
> +  if (OldCpuMpData == NULL) {
> +    CpuMpData->MicrocodePatchRegionSize = PcdGet64 (PcdCpuMicrocodePatchRegionSize);
>      //
> -    // there are multiple processors, and a microcode patch is available, and
> -    // memory allocation succeeded
> +    // If platform has more than one CPU, relocate microcode to memory to reduce
> +    // loading microcode time.
>      //
> -    CopyMem (
> -      MicrocodePatchInRam,
> -      (VOID *)(UINTN)PcdGet64 (PcdCpuMicrocodePatchAddress),
> -      (UINTN)CpuMpData->MicrocodePatchRegionSize
> -      );
> -    CpuMpData->MicrocodePatchAddress = (UINTN)MicrocodePatchInRam;
> +    MicrocodePatchInRam = NULL;
> +    if (MaxLogicalProcessorNumber > 1) {
> +      MicrocodePatchInRam = AllocatePages (
> +                              EFI_SIZE_TO_PAGES (
> +                                (UINTN)CpuMpData->MicrocodePatchRegionSize
> +                                )
> +                              );
> +    }
> +    if (MicrocodePatchInRam == NULL) {
> +      //
> +      // there is only one processor, or no microcode patch is available, or
> +      // memory allocation failed
> +      //
> +      CpuMpData->MicrocodePatchAddress = PcdGet64 (PcdCpuMicrocodePatchAddress);
> +    } else {
> +      //
> +      // there are multiple processors, and a microcode patch is available, and
> +      // memory allocation succeeded
> +      //
> +      CopyMem (
> +        MicrocodePatchInRam,
> +        (VOID *)(UINTN)PcdGet64 (PcdCpuMicrocodePatchAddress),
> +        (UINTN)CpuMpData->MicrocodePatchRegionSize
> +        );
> +      CpuMpData->MicrocodePatchAddress = (UINTN)MicrocodePatchInRam;
> +    }
> +  }else {
> +    CpuMpData->MicrocodePatchRegionSize = OldCpuMpData->MicrocodePatchRegionSize;
> +    CpuMpData->MicrocodePatchAddress    = OldCpuMpData->MicrocodePatchAddress;
>    }
> -
>    InitializeSpinLock(&CpuMpData->MpLock);
>  
>    //
> 

I applied this patch locally and reviewed it with:

  git show -b -W

The change looks reasonable to me.

(1) Please clarify the subject line a bit. My suggestion is:

  UefiCpuPkg/MpInitLib: don't shadow the microcode patch twice

(this is 58 characters). Feel free to tweak this further if you wish;
the point is that "copy" is too generic in itself.


With (1) fixed:

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

Thanks
Laszlo