Re: [edk2-devel] [PATCH 09/16] UefiCpuPkg/MpInitLib: Use CcExitSnpVmsaRmpAdjust() to set/clear VMSA

["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 09/16] UefiCpuPkg/MpInitLib: Use
> CcExitSnpVmsaRmpAdjust() to set/clear VMSA
> 
> BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=4654
> 
> The RMPADJUST instruction is used to change the VMSA attribute of a page,
> but the VMSA attribute can only be changed when running at VMPL0. When
> an
> SVSM is present, use the SVSM_CORE_CREATE_VCPU and
> SVSM_CORE_DELTE_VCPU
> calls to change the VMSA attribute on a page instead of issuing the
> RMPADJUST instruction directly.
> 
> Implement the CcExitSnpVmsaRmpAdjust() API to perform the appropriate
> operation to change the VMSA attribute based on the presence of an SVSM.
> 
> Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
> ---
>  UefiCpuPkg/Library/MpInitLib/MpLib.h       | 14 ------
>  UefiCpuPkg/Library/MpInitLib/Ia32/AmdSev.c | 20 --------
>  UefiCpuPkg/Library/MpInitLib/X64/AmdSev.c  | 53 +++-----------------
>  3 files changed, 6 insertions(+), 81 deletions(-)
> 
> diff --git a/UefiCpuPkg/Library/MpInitLib/MpLib.h
> b/UefiCpuPkg/Library/MpInitLib/MpLib.h
> index a96a6389c17d..6e2137cb17cd 100644
> --- a/UefiCpuPkg/Library/MpInitLib/MpLib.h
> +++ b/UefiCpuPkg/Library/MpInitLib/MpLib.h
> @@ -870,20 +870,6 @@ FillExchangeInfoDataSevEs (
>    IN volatile MP_CPU_EXCHANGE_INFO  *ExchangeInfo
>    );
> 
> -/**
> -  Issue RMPADJUST to adjust the VMSA attribute of an SEV-SNP page.
> -
> -  @param[in]  PageAddress
> -  @param[in]  VmsaPage
> -
> -  @return  RMPADJUST return value
> -**/
> -UINT32
> -SevSnpRmpAdjust (
> -  IN  EFI_PHYSICAL_ADDRESS  PageAddress,
> -  IN  BOOLEAN               VmsaPage
> -  );
> -
>  /**
>    Create an SEV-SNP AP save area (VMSA) for use in running the vCPU.
> 
> diff --git a/UefiCpuPkg/Library/MpInitLib/Ia32/AmdSev.c
> b/UefiCpuPkg/Library/MpInitLib/Ia32/AmdSev.c
> index c83144285b68..a2b8a5b3f516 100644
> --- a/UefiCpuPkg/Library/MpInitLib/Ia32/AmdSev.c
> +++ b/UefiCpuPkg/Library/MpInitLib/Ia32/AmdSev.c
> @@ -48,23 +48,3 @@ SevSnpCreateAP (
>    //
>    ASSERT (FALSE);
>  }
> -
> -/**
> -  Issue RMPADJUST to adjust the VMSA attribute of an SEV-SNP page.
> -
> -  @param[in]  PageAddress
> -  @param[in]  VmsaPage
> -
> -  @return  RMPADJUST return value
> -**/
> -UINT32
> -SevSnpRmpAdjust (
> -  IN  EFI_PHYSICAL_ADDRESS  PageAddress,
> -  IN  BOOLEAN               VmsaPage
> -  )
> -{
> -  //
> -  // RMPADJUST is not supported in 32-bit mode
> -  //
> -  return RETURN_UNSUPPORTED;
> -}
> diff --git a/UefiCpuPkg/Library/MpInitLib/X64/AmdSev.c
> b/UefiCpuPkg/Library/MpInitLib/X64/AmdSev.c
> index c9f0984f41a2..db9a37fbbd19 100644
> --- a/UefiCpuPkg/Library/MpInitLib/X64/AmdSev.c
> +++ b/UefiCpuPkg/Library/MpInitLib/X64/AmdSev.c
> @@ -38,20 +38,15 @@ SevSnpPerformApAction (
>    BOOLEAN                   InterruptState;
>    UINT64                    ExitInfo1;
>    UINT64                    ExitInfo2;
> -  UINT32                    RmpAdjustStatus;
>    UINT64                    VmgExitStatus;
> +  EFI_STATUS                VmsaStatus;
> 
>    if (Action == SVM_VMGEXIT_SNP_AP_CREATE) {
>      //
> -    // To turn the page into a recognized VMSA page, issue RMPADJUST:
> -    //   Target VMPL but numerically higher than current VMPL
> -    //   Target PermissionMask is not used
> +    // Turn the page into a recognized VMSA page.
>      //
> -    RmpAdjustStatus = SevSnpRmpAdjust (
> -                        (EFI_PHYSICAL_ADDRESS)(UINTN)SaveArea,
> -                        TRUE
> -                        );
> -    if (RmpAdjustStatus != 0) {
> +    VmsaStatus = CcExitSnpVmsaRmpAdjust (SaveArea, ApicId, TRUE);
> +    if (EFI_ERROR (VmsaStatus)) {
>        DEBUG ((DEBUG_INFO, "SEV-SNP: RMPADJUST failed for VMSA
> creation\n"));
>        ASSERT (FALSE);
> 
> @@ -94,11 +89,8 @@ SevSnpPerformApAction (
>      // Make the current VMSA not runnable and accessible to be
>      // reprogrammed.
>      //
> -    RmpAdjustStatus = SevSnpRmpAdjust (
> -                        (EFI_PHYSICAL_ADDRESS)(UINTN)SaveArea,
> -                        FALSE
> -                        );
> -    if (RmpAdjustStatus != 0) {
> +    VmsaStatus = CcExitSnpVmsaRmpAdjust (SaveArea, ApicId, FALSE);
> +    if (EFI_ERROR (VmsaStatus)) {
>        DEBUG ((DEBUG_INFO, "SEV-SNP: RMPADJUST failed for VMSA reset\n"));
>        ASSERT (FALSE);
> 
> @@ -292,36 +284,3 @@ SevSnpCreateAP (
>      SevSnpCreateSaveArea (CpuMpData, CpuData, ApicId);
>    }
>  }
> -
> -/**
> -  Issue RMPADJUST to adjust the VMSA attribute of an SEV-SNP page.
> -
> -  @param[in]  PageAddress
> -  @param[in]  VmsaPage
> -
> -  @return  RMPADJUST return value
> -**/
> -UINT32
> -SevSnpRmpAdjust (
> -  IN  EFI_PHYSICAL_ADDRESS  PageAddress,
> -  IN  BOOLEAN               VmsaPage
> -  )
> -{
> -  UINT64  Rdx;
> -
> -  //
> -  // The RMPADJUST instruction is used to set or clear the VMSA bit for a
> -  // page. The VMSA change is only made when running at VMPL0 and is
> ignored
> -  // otherwise. If too low a target VMPL is specified, the instruction can
> -  // succeed without changing the VMSA bit when not running at VMPL0.
> Using a
> -  // target VMPL level of 1, RMPADJUST will return a FAIL_PERMISSION error
> if
> -  // not running at VMPL0, thus ensuring that the VMSA bit is set
> appropriately
> -  // when no error is returned.
> -  //
> -  Rdx = 1;
> -  if (VmsaPage) {
> -    Rdx |= RMPADJUST_VMSA_PAGE_BIT;
> -  }
> -
> -  return AsmRmpAdjust ((UINT64)PageAddress, 0, Rdx);
> -}
> --
> 2.42.0



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