Re: [edk2-devel] [Patch 1/1] UefiCpuPkg: Always load microcode patch on AP processor.

["Dong, Eric" <eric.dong@intel.com>]

Hi Siyuan,

Thanks for your patch.

Reviewed-by: Eric Dong <eric.dong@intel.com>

Thanks,
Eric

> -----Original Message-----
> From: devel@edk2.groups.io [mailto:devel@edk2.groups.io] On Behalf Of
> Siyuan, Fu
> Sent: Friday, January 3, 2020 2:59 PM
> To: devel@edk2.groups.io
> Cc: Dong, Eric <eric.dong@intel.com>; Ni, Ray <ray.ni@intel.com>
> Subject: [edk2-devel] [Patch 1/1] UefiCpuPkg: Always load microcode patch
> on AP processor.
> 
> This patch updates the microcode loader to always perform a microcode
> detect and load on both BSP and AP processor. This is to fix a potential
> microcode revision mismatch issue in below situation:
> 1. Assume there are two microcode co-exists in flash: one production version
>    and one debug version microcode.
> 2. FIT loads production microcode to BSP and all AP.
> 3. UefiCpuPkg loader loads debug microcode to BSP, and skip the loading on
> AP.
> As a result, different microcode patches are loaded to BSP and AP, and
> trigger microcode mismatch error during OS boot.
> 
> Bugzilla: https://bugzilla.tianocore.org/show_bug.cgi?id=2431
> 
> Cc: Eric Dong <eric.dong@intel.com>
> Cc: Ray Ni <ray.ni@intel.com>
> Signed-off-by: Siyuan Fu <siyuan.fu@intel.com>
> ---
>  UefiCpuPkg/Library/MpInitLib/Microcode.c | 8 +-------
>  1 file changed, 1 insertion(+), 7 deletions(-)
> 
> diff --git a/UefiCpuPkg/Library/MpInitLib/Microcode.c
> b/UefiCpuPkg/Library/MpInitLib/Microcode.c
> index 3da5bfb9cf2f..fa6f9681e55a 100644
> --- a/UefiCpuPkg/Library/MpInitLib/Microcode.c
> +++ b/UefiCpuPkg/Library/MpInitLib/Microcode.c
> @@ -1,7 +1,7 @@
>  /** @file
>    Implementation of loading microcode on processors.
> 
> -  Copyright (c) 2015 - 2019, Intel Corporation. All rights reserved.<BR>
> +  Copyright (c) 2015 - 2020, Intel Corporation. All rights
> + reserved.<BR>
>    SPDX-License-Identifier: BSD-2-Clause-Patent
> 
>  **/
> @@ -105,12 +105,6 @@ MicrocodeDetect (
> 
>    CurrentRevision = GetCurrentMicrocodeSignature ();
>    IsBspCallIn     = (ProcessorNumber == (UINTN)CpuMpData->BspNumber) ?
> TRUE : FALSE;
> -  if (CurrentRevision != 0 && !IsBspCallIn) {
> -    //
> -    // Skip loading microcode if it has been loaded successfully
> -    //
> -    return;
> -  }
> 
>    GetProcessorLocationByApicId (GetInitialApicId (), NULL, NULL, &ThreadId);
>    if (ThreadId != 0) {
> --
> 2.19.1.windows.1
> 
> 
>