Re: [edk2-devel] [Patch V3 1/3] UefiCpuPkg/MpInitLib: Eliminate redundant microcode loading in DXE.

["Yuanhao Xie" <yuanhao.xie@intel.com>]

Hi Ray,

In V4, the GetMicrocodePathInfoFromHob() removal is in patch 1 instead of the patch 3.
Comments of MTRRs syncing is a updated.

Thanks
Yuanhao
-----Original Message-----
From: Ni, Ray <ray.ni@intel.com> 
Sent: Thursday, November 23, 2023 9:18 AM
To: Xie, Yuanhao <yuanhao.xie@intel.com>; devel@edk2.groups.io
Cc: Dong, Eric <eric.dong@intel.com>; Kumar, Rahul R <rahul.r.kumar@intel.com>; Tom Lendacky <thomas.lendacky@amd.com>; Laszlo Ersek <lersek@redhat.com>
Subject: RE: [Patch V3 1/3] UefiCpuPkg/MpInitLib: Eliminate redundant microcode loading in DXE.


> -  MicrocodeDetect (CpuMpData, ProcessorNumber);
> -  //
> -  // Sync BSP's MTRR table to AP
> +  // Synchronizing the MTRR table to the AP is always essential.
> +  // During the DXE phase, it cannot be omitted like loading 
> + microcode,  // as the PEI and DXE may be in different bit modes.


"as the PEI and DXE may be in different bit modes" is not the reason that MTRR sync needs to be performed in DXE phase.

The reason is some code might change MTRR on BSP only after CpuMp PPI service is not available and before CpuMp Protocol is available.
That is in early DXE phase before CpuMp protocol is installed.

>    //
>    MtrrSetAllMtrrs (&CpuMpData->MtrrTable);  }

-----Original Message-----
From: Ni, Ray <ray.ni@intel.com> 
Sent: Thursday, November 23, 2023 9:19 AM
To: Xie, Yuanhao <yuanhao.xie@intel.com>; devel@edk2.groups.io
Cc: Dong, Eric <eric.dong@intel.com>; Kumar, Rahul R <rahul.r.kumar@intel.com>; Tom Lendacky <thomas.lendacky@amd.com>; Laszlo Ersek <lersek@redhat.com>
Subject: RE: [Patch V3 1/3] UefiCpuPkg/MpInitLib: Eliminate redundant microcode loading in DXE.

> 
> -  if (!GetMicrocodePatchInfoFromHob (
> -         &CpuMpData->MicrocodePatchAddress,
> -         &CpuMpData->MicrocodePatchRegionSize
> -         ))
> -  {

Can you delete the GetMicrocodePathInfoFromHob() in this patch instead of the 3rd patch?


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