Re: [edk2-devel] [Patch V3] UefiCpuPkg: Decouple the SEV-ES functionality.

["Lendacky, Thomas via groups.io" <thomas.lendacky=amd.com@groups.io>]

On 7/26/23 02:51, YuanhaoXie wrote:
> The purpose is to fix an issue where an exception occurs at the start
> of the DXE phase by applying the following patch series on INTEL-based
> systems.
> 
> UefiCpuPkg: Refactor the logic for placing APs in HltLoop.
> UefiCpuPkg: Refactor the logic for placing APs in Mwait/Runloop.
> UefiCpuPkg: Create MpHandOff.
> UefiCpuPkg: ApWakeupFunction directly use CpuMpData.
> UefiCpuPkg: Eliminate the second INIT-SIPI-SIPI sequence.
> 
> This series of patches makes changes to the way the APs are
> initialized and woken up. It removes the 2nd time INIT-SIPI-SIPI and
> introduces a special startup signal to wake up APs. These patches also
> create a new HOB identified by the mMpHandOffGuid, which stores only the
>   minimum information required from the PEI phase to the DXE phase.
> As a result, the original HOB (mCpuInitMpLibHobGuid) is now used only
> as a global variable in the PEI phase and is no longer necessary in the
> DXE phase for INTEL-based systems. The AMD SEV-ES related code
> still relies on the OldCpuMpData in the DXE phase.
> 
> This patch decouple the SEV-ES functionality of assigning CpuMpData to
> OldCpuMpData->NewCpuMpData from the Intel logic.
> 
> Cc: Eric Dong <eric.dong@intel.com>
> Cc: Rahul Kumar <rahul1.kumar@intel.com>
> Cc: Tom Lendacky <thomas.lendacky@amd.com>
> Cc: Ray Ni <ray.ni@intel.com>
> Signed-off-by: Yuanhao Xie <yuanhao.xie@intel.com>
> ---
>   UefiCpuPkg/Library/MpInitLib/MpLib.c | 5 ++++-
>   1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/UefiCpuPkg/Library/MpInitLib/MpLib.c b/UefiCpuPkg/Library/MpInitLib/MpLib.c
> index 737e03ffc5..e7054adbcc 100644
> --- a/UefiCpuPkg/Library/MpInitLib/MpLib.c
> +++ b/UefiCpuPkg/Library/MpInitLib/MpLib.c
> @@ -2160,7 +2160,10 @@ MpInitLibInitialize (
>       // APs have been wakeup before, just get the CPU Information
>       // from HOB
>       //
> -    AmdSevUpdateCpuMpData (CpuMpData);
> +    if (CpuMpData->UseSevEsAPMethod) {
> +      AmdSevUpdateCpuMpData (CpuMpData);
> +    }

This looks fine. Applying this patch did not regress SEV-ES or SEV-SNP 
guest boots.

Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>

Thanks,
Tom

> +
>       CpuMpData->CpuCount  = MpHandOff->CpuCount;
>       CpuMpData->BspNumber = GetBspNumber (MpHandOff);
>       CpuInfoInHob         = (CPU_INFO_IN_HOB *)(UINTN)CpuMpData->CpuInfoInHob;


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