Re: [edk2-devel] [PATCH 14/16] UefiCpuPkg/MpInitLib: AP creation support under an SVSM

["Ni, Ray" <ray.ni@intel.com>]

Acked-by: Ray Ni <ray.ni@intel.com>

Thanks,
Ray
> -----Original Message-----
> From: Tom Lendacky <thomas.lendacky@amd.com>
> Sent: Saturday, January 27, 2024 6:13 AM
> To: devel@edk2.groups.io
> Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>; Aktas, Erdem
> <erdemaktas@google.com>; Gerd Hoffmann <kraxel@redhat.com>; Yao,
> Jiewen <jiewen.yao@intel.com>; Laszlo Ersek <lersek@redhat.com>; Liming
> Gao <gaoliming@byosoft.com.cn>; Kinney, Michael D
> <michael.d.kinney@intel.com>; Xu, Min M <min.m.xu@intel.com>; Liu,
> Zhiguang <zhiguang.liu@intel.com>; Kumar, Rahul R
> <rahul.r.kumar@intel.com>; Ni, Ray <ray.ni@intel.com>; Michael Roth
> <michael.roth@amd.com>
> Subject: [PATCH 14/16] UefiCpuPkg/MpInitLib: AP creation support under an
> SVSM
> 
> BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=4654
> 
> When running under an SVSM, the VMPL level of the APs that are started
> must match the VMPL level provided by the SVSM. Additionally, each AP
> must have a Calling Area for use with the SVSM protocol. Update the AP
> creation to properly support running under an SVSM.
> 
> Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
> ---
>  UefiCpuPkg/Library/MpInitLib/X64/AmdSev.c | 19 +++++++++++++------
>  1 file changed, 13 insertions(+), 6 deletions(-)
> 
> diff --git a/UefiCpuPkg/Library/MpInitLib/X64/AmdSev.c
> b/UefiCpuPkg/Library/MpInitLib/X64/AmdSev.c
> index 6186a8d71521..9b00c945e13d 100644
> --- a/UefiCpuPkg/Library/MpInitLib/X64/AmdSev.c
> +++ b/UefiCpuPkg/Library/MpInitLib/X64/AmdSev.c
> @@ -55,6 +55,7 @@ SevSnpPerformApAction (
>    }
> 
>    ExitInfo1  = (UINT64)ApicId << 32;
> +  ExitInfo1 |= (UINT64)SaveArea->Vmpl << 16;
>    ExitInfo1 |= Action;
>    ExitInfo2  = (UINT64)(UINTN)SaveArea;
> 
> @@ -115,6 +116,7 @@ SevSnpCreateSaveArea (
>    UINT32          ApicId
>    )
>  {
> +  UINTN             PageCount;
>    UINT8             *Pages;
>    SEV_ES_SAVE_AREA  *SaveArea;
>    IA32_CR0          ApCr0;
> @@ -124,13 +126,18 @@ SevSnpCreateSaveArea (
>    UINTN             StartIp;
>    UINT8             SipiVector;
> 
> +  //
> +  // When running under an SVSM, a Calling Area page is also needed
> +  //
> +  PageCount = CcExitSnpSvsmPresent () ? 2 : 1;
> +
>    if (CpuData->SevEsSaveArea == NULL) {
>      //
>      // Allocate a page for the SEV-ES Save Area and initialize it. Due to AMD
>      // erratum #1467 (VMSA cannot be on a 2MB boundary), allocate an extra
> page
>      // to choose from to work around the issue.
>      //
> -    Pages = AllocateReservedPages (2);
> +    Pages = AllocateReservedPages (PageCount + 1);
>      if (!Pages) {
>        return;
>      }
> @@ -139,12 +146,12 @@ SevSnpCreateSaveArea (
>      // Since page allocation works by allocating downward in the address space,
>      // try to always free the first (lower address) page to limit possible holes
>      // in the memory map. So, if the address of the second page is 2MB aligned,
> -    // then use the first page and free the second page. Otherwise, free the
> +    // then use the first page and free the last page. Otherwise, free the
>      // first page and use the second page.
>      //
>      if (_IS_ALIGNED (Pages + EFI_PAGE_SIZE, SIZE_2MB)) {
>        SaveArea = (SEV_ES_SAVE_AREA *)Pages;
> -      FreePages (Pages + EFI_PAGE_SIZE, 1);
> +      FreePages (Pages + (EFI_PAGE_SIZE * PageCount), 1);
>      } else {
>        SaveArea = (SEV_ES_SAVE_AREA *)(Pages + EFI_PAGE_SIZE);
>        FreePages (Pages, 1);
> @@ -162,7 +169,7 @@ SevSnpCreateSaveArea (
>      }
>    }
> 
> -  ZeroMem (SaveArea, EFI_PAGE_SIZE);
> +  ZeroMem (SaveArea, EFI_PAGE_SIZE * PageCount);
> 
>    //
>    // Propogate the CR0.NW and CR0.CD setting to the AP
> @@ -238,10 +245,10 @@ SevSnpCreateSaveArea (
> 
>    //
>    // Set the SEV-SNP specific fields for the save area:
> -  //   VMPL - always VMPL0
> +  //   VMPL - based on current mode
>    //   SEV_FEATURES - equivalent to the SEV_STATUS MSR right shifted 2 bits
>    //
> -  SaveArea->Vmpl        = 0;
> +  SaveArea->Vmpl        = CcExitSnpGetVmpl ();
>    SaveArea->SevFeatures = AsmReadMsr64 (MSR_SEV_STATUS) >> 2;
> 
>    SevSnpPerformApAction (SaveArea, ApicId,
> SVM_VMGEXIT_SNP_AP_CREATE);
> --
> 2.42.0



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