Re: [edk2-devel] [PATCH 05/12] OvmfPkg/MemEncryptSevLib: Add an interface to retrieve the encryption mask

["Lendacky, Thomas" <thomas.lendacky@amd.com>]

On 1/4/21 2:34 PM, Laszlo Ersek wrote:
> On 12/15/20 21:51, Lendacky, Thomas wrote:
>> From: Tom Lendacky <thomas.lendacky@amd.com>
>>
>> BZ: https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fbugzilla.tianocore.org%2Fshow_bug.cgi%3Fid%3D3108&amp;data=04%7C01%7Cthomas.lendacky%40amd.com%7Ca6820182d19f4e0821d908d8b0f01c5f%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637453892632471236%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&amp;sdata=pXsRpEk6pQPZUiqtY1OUzmcsjflNq5nTN6I6%2F%2F1d8VI%3D&amp;reserved=0
>>
>> The early assembler code performs validation for some of the SEV-related
>> information, specifically the encryption bit position. To avoid having to
>> re-validate the encryption bit position as the system proceeds through its
>> boot phases, use the saved information from the SEV-ES work area during
>> PEI and PcdPteMemoryEncryptionAddressOrMask (set during PEI) during DXE.
> 
> (1) Please replace
> 
>    and
> 
> on the last line, with
> 
>    , and
> 

Will do.

> Without the comma, it's too easy to misread the message as "use [blah]
> during PEI and PcdPteMemoryEncryptionAddressOrMask" -- i.e., as if
> "during" applied to "PEI" and "PcdPteMemoryEncryptionAddressOrMask"
> alike. Which of course makes no sense.
> 
>>
>> To ensure that we always use a validated encryption mask for an SEV-ES
>> guest, create a new interface in the MemEncryptSevLib library to return
>> the encryption mask. This avoids the multiple locations where CPUID is
>> used to retrieve the value and allows the validated mask to be returned.
>>
>> Update all locations that use CPUID to calculate the encryption mask to
>> use the new interface. Also, clean up some call areas where extra masking
>> was being performed and where a function call was being used instead of
>> the local variable that was just set using the function.
>>
>> Cc: Jordan Justen <jordan.l.justen@intel.com>
>> Cc: Laszlo Ersek <lersek@redhat.com>
>> Cc: Ard Biesheuvel <ard.biesheuvel@arm.com>
>> Cc: Rebecca Cran <rebecca@bsdio.com>
>> Cc: Peter Grehan <grehan@freebsd.org>
>> Cc: Anthony Perard <anthony.perard@citrix.com>
>> Cc: Julien Grall <julien@xen.org>
>> Cc: Brijesh Singh <brijesh.singh@amd.com>
>> Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
>> ---
>>   OvmfPkg/AmdSev/AmdSevX64.dsc                  |   4 +-
>>   OvmfPkg/Bhyve/BhyveX64.dsc                    |   4 +-
>>   OvmfPkg/OvmfPkgIa32.dsc                       |   4 +-
>>   OvmfPkg/OvmfPkgIa32X64.dsc                    |   4 +-
>>   OvmfPkg/OvmfPkgX64.dsc                        |   4 +-
>>   OvmfPkg/OvmfXen.dsc                           |   3 +-
>>   ...SevLib.inf => DxeBaseMemEncryptSevLib.inf} |  13 +-
>>   .../PeiBaseMemEncryptSevLib.inf               |  56 ++++++
>>   OvmfPkg/Include/Library/MemEncryptSevLib.h    |  14 ++
>>   OvmfPkg/Bhyve/PlatformPei/AmdSev.c            |  12 +-
>>   .../DxeMemEncryptSevLibInternal.c             | 145 ++++++++++++++++
>>   .../MemEncryptSevLibInternal.c                |  91 +---------
>>   .../PeiMemEncryptSevLibInternal.c             | 159 ++++++++++++++++++
>>   .../BaseMemEncryptSevLib/X64/VirtualMemory.c  |  15 +-
>>   OvmfPkg/PlatformPei/AmdSev.c                  |  12 +-
>>   OvmfPkg/XenPlatformPei/AmdSev.c               |  12 +-
>>   OvmfPkg/ResetVector/Ia32/PageTables64.asm     |  10 +-
>>   OvmfPkg/ResetVector/ResetVector.nasmb         |   1 +
>>   18 files changed, 422 insertions(+), 141 deletions(-)
>>   rename OvmfPkg/Library/BaseMemEncryptSevLib/{BaseMemEncryptSevLib.inf => DxeBaseMemEncryptSevLib.inf} (67%)
>>   create mode 100644 OvmfPkg/Library/BaseMemEncryptSevLib/PeiBaseMemEncryptSevLib.inf
>>   create mode 100644 OvmfPkg/Library/BaseMemEncryptSevLib/DxeMemEncryptSevLibInternal.c
>>   create mode 100644 OvmfPkg/Library/BaseMemEncryptSevLib/PeiMemEncryptSevLibInternal.c
> 
> (2) "DxeBase" should be just "Dxe", and "PeiBase" should just be "Pei".
> 
> The BASE_NAME defines in the INF files are correct already, but the
> names of those INF files, and the references to them in the DSC files,
> are not.

Yup, will fix.

> 
>>
>> diff --git a/OvmfPkg/AmdSev/AmdSevX64.dsc b/OvmfPkg/AmdSev/AmdSevX64.dsc
>> index bb7697eb324b..c742ec54cb57 100644
>> --- a/OvmfPkg/AmdSev/AmdSevX64.dsc
>> +++ b/OvmfPkg/AmdSev/AmdSevX64.dsc
>> @@ -164,7 +164,7 @@ [LibraryClasses]
>>     QemuFwCfgSimpleParserLib|OvmfPkg/Library/QemuFwCfgSimpleParserLib/QemuFwCfgSimpleParserLib.inf
>>     VirtioLib|OvmfPkg/Library/VirtioLib/VirtioLib.inf
>>     LoadLinuxLib|OvmfPkg/Library/LoadLinuxLib/LoadLinuxLib.inf
>> -  MemEncryptSevLib|OvmfPkg/Library/BaseMemEncryptSevLib/BaseMemEncryptSevLib.inf
>> +  MemEncryptSevLib|OvmfPkg/Library/BaseMemEncryptSevLib/DxeBaseMemEncryptSevLib.inf
>>     LockBoxLib|OvmfPkg/Library/LockBoxLib/LockBoxBaseLib.inf
>>     CustomizedDisplayLib|MdeModulePkg/Library/CustomizedDisplayLib/CustomizedDisplayLib.inf
>>     FrameBufferBltLib|MdeModulePkg/Library/FrameBufferBltLib/FrameBufferBltLib.inf
>> @@ -285,6 +285,8 @@ [LibraryClasses.common.PEIM]
>>     Tpm2DeviceLib|SecurityPkg/Library/Tpm2DeviceLibDTpm/Tpm2DeviceLibDTpm.inf
>>   !endif
>>   
>> +  MemEncryptSevLib|OvmfPkg/Library/BaseMemEncryptSevLib/PeiBaseMemEncryptSevLib.inf
>> +
>>   [LibraryClasses.common.DXE_CORE]
>>     HobLib|MdePkg/Library/DxeCoreHobLib/DxeCoreHobLib.inf
>>     DxeCoreEntryPoint|MdePkg/Library/DxeCoreEntryPoint/DxeCoreEntryPoint.inf
>> diff --git a/OvmfPkg/Bhyve/BhyveX64.dsc b/OvmfPkg/Bhyve/BhyveX64.dsc
>> index b93fe30ae4e0..27973bc940d5 100644
>> --- a/OvmfPkg/Bhyve/BhyveX64.dsc
>> +++ b/OvmfPkg/Bhyve/BhyveX64.dsc
>> @@ -163,7 +163,7 @@ [LibraryClasses]
>>     QemuFwCfgS3Lib|OvmfPkg/Library/QemuFwCfgS3Lib/BaseQemuFwCfgS3LibNull.inf
>>     BhyveFwCtlLib|OvmfPkg/Library/BhyveFwCtlLib/BhyveFwCtlLib.inf
>>     VirtioLib|OvmfPkg/Library/VirtioLib/VirtioLib.inf
>> -  MemEncryptSevLib|OvmfPkg/Library/BaseMemEncryptSevLib/BaseMemEncryptSevLib.inf
>> +  MemEncryptSevLib|OvmfPkg/Library/BaseMemEncryptSevLib/DxeBaseMemEncryptSevLib.inf
>>     LockBoxLib|OvmfPkg/Library/LockBoxLib/LockBoxBaseLib.inf
>>   
>>     CustomizedDisplayLib|MdeModulePkg/Library/CustomizedDisplayLib/CustomizedDisplayLib.inf
>> @@ -292,6 +292,8 @@ [LibraryClasses.common.PEIM]
>>     Tpm2DeviceLib|SecurityPkg/Library/Tpm2DeviceLibDTpm/Tpm2DeviceLibDTpm.inf
>>   !endif
>>   
>> +  MemEncryptSevLib|OvmfPkg/Library/BaseMemEncryptSevLib/PeiBaseMemEncryptSevLib.inf
>> +
>>   [LibraryClasses.common.DXE_CORE]
>>     HobLib|MdePkg/Library/DxeCoreHobLib/DxeCoreHobLib.inf
>>     DxeCoreEntryPoint|MdePkg/Library/DxeCoreEntryPoint/DxeCoreEntryPoint.inf
>> diff --git a/OvmfPkg/OvmfPkgIa32.dsc b/OvmfPkg/OvmfPkgIa32.dsc
>> index 8eede796a8bd..e433e17dc807 100644
>> --- a/OvmfPkg/OvmfPkgIa32.dsc
>> +++ b/OvmfPkg/OvmfPkgIa32.dsc
>> @@ -169,7 +169,7 @@ [LibraryClasses]
>>     QemuFwCfgSimpleParserLib|OvmfPkg/Library/QemuFwCfgSimpleParserLib/QemuFwCfgSimpleParserLib.inf
>>     VirtioLib|OvmfPkg/Library/VirtioLib/VirtioLib.inf
>>     LoadLinuxLib|OvmfPkg/Library/LoadLinuxLib/LoadLinuxLib.inf
>> -  MemEncryptSevLib|OvmfPkg/Library/BaseMemEncryptSevLib/BaseMemEncryptSevLib.inf
>> +  MemEncryptSevLib|OvmfPkg/Library/BaseMemEncryptSevLib/DxeBaseMemEncryptSevLib.inf
>>   !if $(SMM_REQUIRE) == FALSE
>>     LockBoxLib|OvmfPkg/Library/LockBoxLib/LockBoxBaseLib.inf
>>   !endif
>> @@ -309,6 +309,8 @@ [LibraryClasses.common.PEIM]
>>     Tpm2DeviceLib|SecurityPkg/Library/Tpm2DeviceLibDTpm/Tpm2DeviceLibDTpm.inf
>>   !endif
>>   
>> +  MemEncryptSevLib|OvmfPkg/Library/BaseMemEncryptSevLib/PeiBaseMemEncryptSevLib.inf
>> +
>>   [LibraryClasses.common.DXE_CORE]
>>     HobLib|MdePkg/Library/DxeCoreHobLib/DxeCoreHobLib.inf
>>     DxeCoreEntryPoint|MdePkg/Library/DxeCoreEntryPoint/DxeCoreEntryPoint.inf
>> diff --git a/OvmfPkg/OvmfPkgIa32X64.dsc b/OvmfPkg/OvmfPkgIa32X64.dsc
>> index f9f82a48f4b9..2e2eefbe33f0 100644
>> --- a/OvmfPkg/OvmfPkgIa32X64.dsc
>> +++ b/OvmfPkg/OvmfPkgIa32X64.dsc
>> @@ -173,7 +173,7 @@ [LibraryClasses]
>>     QemuFwCfgSimpleParserLib|OvmfPkg/Library/QemuFwCfgSimpleParserLib/QemuFwCfgSimpleParserLib.inf
>>     VirtioLib|OvmfPkg/Library/VirtioLib/VirtioLib.inf
>>     LoadLinuxLib|OvmfPkg/Library/LoadLinuxLib/LoadLinuxLib.inf
>> -  MemEncryptSevLib|OvmfPkg/Library/BaseMemEncryptSevLib/BaseMemEncryptSevLib.inf
>> +  MemEncryptSevLib|OvmfPkg/Library/BaseMemEncryptSevLib/DxeBaseMemEncryptSevLib.inf
>>   !if $(SMM_REQUIRE) == FALSE
>>     LockBoxLib|OvmfPkg/Library/LockBoxLib/LockBoxBaseLib.inf
>>   !endif
>> @@ -313,6 +313,8 @@ [LibraryClasses.common.PEIM]
>>     Tpm2DeviceLib|SecurityPkg/Library/Tpm2DeviceLibDTpm/Tpm2DeviceLibDTpm.inf
>>   !endif
>>   
>> +  MemEncryptSevLib|OvmfPkg/Library/BaseMemEncryptSevLib/PeiBaseMemEncryptSevLib.inf
>> +
>>   [LibraryClasses.common.DXE_CORE]
>>     HobLib|MdePkg/Library/DxeCoreHobLib/DxeCoreHobLib.inf
>>     DxeCoreEntryPoint|MdePkg/Library/DxeCoreEntryPoint/DxeCoreEntryPoint.inf
>> diff --git a/OvmfPkg/OvmfPkgX64.dsc b/OvmfPkg/OvmfPkgX64.dsc
>> index e59ae05b73aa..3e008855fbc1 100644
>> --- a/OvmfPkg/OvmfPkgX64.dsc
>> +++ b/OvmfPkg/OvmfPkgX64.dsc
>> @@ -173,7 +173,7 @@ [LibraryClasses]
>>     QemuFwCfgSimpleParserLib|OvmfPkg/Library/QemuFwCfgSimpleParserLib/QemuFwCfgSimpleParserLib.inf
>>     VirtioLib|OvmfPkg/Library/VirtioLib/VirtioLib.inf
>>     LoadLinuxLib|OvmfPkg/Library/LoadLinuxLib/LoadLinuxLib.inf
>> -  MemEncryptSevLib|OvmfPkg/Library/BaseMemEncryptSevLib/BaseMemEncryptSevLib.inf
>> +  MemEncryptSevLib|OvmfPkg/Library/BaseMemEncryptSevLib/DxeBaseMemEncryptSevLib.inf
>>   !if $(SMM_REQUIRE) == FALSE
>>     LockBoxLib|OvmfPkg/Library/LockBoxLib/LockBoxBaseLib.inf
>>   !endif
>> @@ -313,6 +313,8 @@ [LibraryClasses.common.PEIM]
>>     Tpm2DeviceLib|SecurityPkg/Library/Tpm2DeviceLibDTpm/Tpm2DeviceLibDTpm.inf
>>   !endif
>>   
>> +  MemEncryptSevLib|OvmfPkg/Library/BaseMemEncryptSevLib/PeiBaseMemEncryptSevLib.inf
>> +
>>   [LibraryClasses.common.DXE_CORE]
>>     HobLib|MdePkg/Library/DxeCoreHobLib/DxeCoreHobLib.inf
>>     DxeCoreEntryPoint|MdePkg/Library/DxeCoreEntryPoint/DxeCoreEntryPoint.inf
>> diff --git a/OvmfPkg/OvmfXen.dsc b/OvmfPkg/OvmfXen.dsc
>> index 12b7a87ee877..44fae364b423 100644
>> --- a/OvmfPkg/OvmfXen.dsc
>> +++ b/OvmfPkg/OvmfXen.dsc
>> @@ -161,7 +161,7 @@ [LibraryClasses]
>>     SerializeVariablesLib|OvmfPkg/Library/SerializeVariablesLib/SerializeVariablesLib.inf
>>     QemuFwCfgLib|OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgDxeLib.inf
>>     QemuLoadImageLib|OvmfPkg/Library/GenericQemuLoadImageLib/GenericQemuLoadImageLib.inf
>> -  MemEncryptSevLib|OvmfPkg/Library/BaseMemEncryptSevLib/BaseMemEncryptSevLib.inf
>> +  MemEncryptSevLib|OvmfPkg/Library/BaseMemEncryptSevLib/DxeBaseMemEncryptSevLib.inf
>>     LockBoxLib|OvmfPkg/Library/LockBoxLib/LockBoxBaseLib.inf
>>     CustomizedDisplayLib|MdeModulePkg/Library/CustomizedDisplayLib/CustomizedDisplayLib.inf
>>     FrameBufferBltLib|MdeModulePkg/Library/FrameBufferBltLib/FrameBufferBltLib.inf
>> @@ -273,6 +273,7 @@ [LibraryClasses.common.PEIM]
>>     QemuFwCfgS3Lib|OvmfPkg/Library/QemuFwCfgS3Lib/PeiQemuFwCfgS3LibFwCfg.inf
>>     PcdLib|MdePkg/Library/PeiPcdLib/PeiPcdLib.inf
>>     QemuFwCfgLib|OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgPeiLib.inf
>> +  MemEncryptSevLib|OvmfPkg/Library/BaseMemEncryptSevLib/PeiBaseMemEncryptSevLib.inf
>>   
>>   [LibraryClasses.common.DXE_CORE]
>>     HobLib|MdePkg/Library/DxeCoreHobLib/DxeCoreHobLib.inf
>> diff --git a/OvmfPkg/Library/BaseMemEncryptSevLib/BaseMemEncryptSevLib.inf b/OvmfPkg/Library/BaseMemEncryptSevLib/DxeBaseMemEncryptSevLib.inf
>> similarity index 67%
>> rename from OvmfPkg/Library/BaseMemEncryptSevLib/BaseMemEncryptSevLib.inf
>> rename to OvmfPkg/Library/BaseMemEncryptSevLib/DxeBaseMemEncryptSevLib.inf
>> index 7c44d0952815..2be6ca1fa737 100644
>> --- a/OvmfPkg/Library/BaseMemEncryptSevLib/BaseMemEncryptSevLib.inf
>> +++ b/OvmfPkg/Library/BaseMemEncryptSevLib/DxeBaseMemEncryptSevLib.inf
>> @@ -1,7 +1,7 @@
>>   ## @file
>>   #  Library provides the helper functions for SEV guest
>>   #
>> -# Copyright (c) 2017 Advanced Micro Devices. All rights reserved.<BR>
>> +# Copyright (c) 2017 - 2020, Advanced Micro Devices. All rights reserved.<BR>
>>   #
>>   #  SPDX-License-Identifier: BSD-2-Clause-Patent
>>   #
>> @@ -10,11 +10,11 @@
>>   
>>   [Defines]
>>     INF_VERSION                    = 1.25
>> -  BASE_NAME                      = MemEncryptSevLib
>> +  BASE_NAME                      = DxeMemEncryptSevLib
>>     FILE_GUID                      = c1594631-3888-4be4-949f-9c630dbc842b
>>     MODULE_TYPE                    = BASE
>>     VERSION_STRING                 = 1.0
>> -  LIBRARY_CLASS                  = MemEncryptSevLib|PEIM DXE_DRIVER DXE_RUNTIME_DRIVER DXE_SMM_DRIVER UEFI_DRIVER
>> +  LIBRARY_CLASS                  = MemEncryptSevLib|DXE_DRIVER DXE_RUNTIME_DRIVER DXE_SMM_DRIVER UEFI_DRIVER
>>   
>>   #
>>   # The following information is for reference only and not required by the build
>> @@ -30,14 +30,16 @@ [Packages]
>>     UefiCpuPkg/UefiCpuPkg.dec
>>   
>>   [Sources.X64]
>> +  DxeMemEncryptSevLibInternal.c
>>     MemEncryptSevLibInternal.c
>>     X64/MemEncryptSevLib.c
>>     X64/VirtualMemory.c
>>     X64/VirtualMemory.h
>>   
>>   [Sources.IA32]
>> +  DxeMemEncryptSevLibInternal.c
>> +  MemEncryptSevLibInternal.c
>>     Ia32/MemEncryptSevLib.c
>> -  MemEncryptSevLibInternal.c
>>   
>>   [LibraryClasses]
>>     BaseLib
>> @@ -49,3 +51,6 @@ [LibraryClasses]
>>   
>>   [FeaturePcd]
>>     gUefiOvmfPkgTokenSpaceGuid.PcdSmmSmramRequire
>> +
>> +[Pcd]
>> +  gEfiMdeModulePkgTokenSpaceGuid.PcdPteMemoryEncryptionAddressOrMask
>> diff --git a/OvmfPkg/Library/BaseMemEncryptSevLib/PeiBaseMemEncryptSevLib.inf b/OvmfPkg/Library/BaseMemEncryptSevLib/PeiBaseMemEncryptSevLib.inf
>> new file mode 100644
>> index 000000000000..7bdf8cb5210d
>> --- /dev/null
>> +++ b/OvmfPkg/Library/BaseMemEncryptSevLib/PeiBaseMemEncryptSevLib.inf
>> @@ -0,0 +1,56 @@
>> +## @file
>> +#  Library provides the helper functions for SEV guest
>> +#
>> +# Copyright (c) 2020 Advanced Micro Devices. All rights reserved.<BR>
>> +#
>> +#  SPDX-License-Identifier: BSD-2-Clause-Patent
>> +#
>> +#
>> +##
>> +
>> +[Defines]
>> +  INF_VERSION                    = 1.25
>> +  BASE_NAME                      = PeiMemEncryptSevLib
>> +  FILE_GUID                      = 15d9a694-3d2a-4184-9672-ba55c3070e07
>> +  MODULE_TYPE                    = BASE
>> +  VERSION_STRING                 = 1.0
>> +  LIBRARY_CLASS                  = MemEncryptSevLib|PEIM
>> +
>> +#
>> +# The following information is for reference only and not required by the build
>> +# tools.
>> +#
>> +# VALID_ARCHITECTURES           = IA32 X64
>> +#
>> +
>> +[Packages]
>> +  MdeModulePkg/MdeModulePkg.dec
>> +  MdePkg/MdePkg.dec
>> +  OvmfPkg/OvmfPkg.dec
>> +  UefiCpuPkg/UefiCpuPkg.dec
>> +
>> +[Sources.X64]
>> +  PeiMemEncryptSevLibInternal.c
>> +  MemEncryptSevLibInternal.c
>> +  X64/MemEncryptSevLib.c
>> +  X64/VirtualMemory.c
>> +  X64/VirtualMemory.h
>> +
>> +[Sources.IA32]
>> +  PeiMemEncryptSevLibInternal.c
>> +  MemEncryptSevLibInternal.c
>> +  Ia32/MemEncryptSevLib.c
>> +
>> +[LibraryClasses]
>> +  BaseLib
>> +  CacheMaintenanceLib
>> +  CpuLib
>> +  DebugLib
>> +  MemoryAllocationLib
>> +  PcdLib
>> +
>> +[FeaturePcd]
>> +  gUefiOvmfPkgTokenSpaceGuid.PcdSmmSmramRequire
>> +
>> +[FixedPcd]
>> +  gUefiCpuPkgTokenSpaceGuid.PcdSevEsWorkAreaBase
> 
> (3) In each INF file:
> 
> I suggest moving the files shared between X64 and IA32 to a plain
> [Sources] section (i.e., no architecture modifier). I do agree that the
> pre-patch status is already not ideal (as "MemEncryptSevLibInternal.c"
> is duplicated between the [Sources.IA32] and [Sources.X64] sections),
> but since you already move "MemEncryptSevLibInternal.c" a bit, we might
> as well move as much as possible under a new [Sources] section.
> 
> Again this applies to both INF files.

Will do.

> 
>> diff --git a/OvmfPkg/Include/Library/MemEncryptSevLib.h b/OvmfPkg/Include/Library/MemEncryptSevLib.h
>> index dc09c61e58bb..394065f15bc1 100644
>> --- a/OvmfPkg/Include/Library/MemEncryptSevLib.h
>> +++ b/OvmfPkg/Include/Library/MemEncryptSevLib.h
>> @@ -29,6 +29,8 @@ typedef struct _SEC_SEV_ES_WORK_AREA {
>>     UINT8    Reserved1[7];
>>   
>>     UINT64   RandomData;
>> +
>> +  UINT64   EncryptionMask;
>>   } SEC_SEV_ES_WORK_AREA;
>>   
>>   /**
>> @@ -133,4 +135,16 @@ MemEncryptSevLocateInitialSmramSaveStateMapPages (
>>     OUT UINTN *BaseAddress,
>>     OUT UINTN *NumberOfPages
>>     );
>> +
>> +/**
>> +  Returns the SEV encryption mask.
>> +
>> +  @return  The SEV pagtable encryption mask
> 
> (4) Typo: "pagtable".

Will fix.

> 
>> +**/
>> +UINT64
>> +EFIAPI
>> +MemEncryptSevGetEncryptionMask (
>> +  VOID
>> +  );
>> +
>>   #endif // _MEM_ENCRYPT_SEV_LIB_H_
> 
> (5) The contents of this patch makes sense, but the patch is too large
> for my taste. Please split it to 3 patches:
> 
> - Save the mask in the reset vector to a new field in the work area.
> 
> - Introduce the new API to the lib class (and introduce both lib
> instances too). Reworking "VirtualMemory.c" in this same patch is fine.
> 
> - Migrate the consumers of the mask to the new API (as far as I can
> tell, these are the three PlatformPei modules).

Ok, I'll start working on that.

> 
> (6) Please confirm that you've successfully built all six modified DSC
> files.
> 
> For Bhyve, you need nothing extra (similarly to Xen).
> 
> For test-building "OvmfPkg/AmdSev/AmdSevX64.dsc", you need to palce any
> random grub.efi binary at "OvmfPkg/AmdSev/Grub/grub.efi".

Will do.

Thanks,
Tom

> 
> Thanks,
> Laszlo
> 
>> diff --git a/OvmfPkg/Bhyve/PlatformPei/AmdSev.c b/OvmfPkg/Bhyve/PlatformPei/AmdSev.c
>> index e484f4b311fe..e3ed78581c1b 100644
>> --- a/OvmfPkg/Bhyve/PlatformPei/AmdSev.c
>> +++ b/OvmfPkg/Bhyve/PlatformPei/AmdSev.c
>> @@ -1,7 +1,7 @@
>>   /**@file
>>     Initialize Secure Encrypted Virtualization (SEV) support
>>   
>> -  Copyright (c) 2017, Advanced Micro Devices. All rights reserved.<BR>
>> +  Copyright (c) 2017 - 2020, Advanced Micro Devices. All rights reserved.<BR>
>>   
>>     SPDX-License-Identifier: BSD-2-Clause-Patent
>>   
>> @@ -15,8 +15,6 @@
>>   #include <Library/MemEncryptSevLib.h>
>>   #include <Library/PcdLib.h>
>>   #include <PiPei.h>
>> -#include <Register/Amd/Cpuid.h>
>> -#include <Register/Cpuid.h>
>>   #include <Register/Intel/SmramSaveStateMap.h>
>>   
>>   #include "Platform.h"
>> @@ -32,7 +30,6 @@ AmdSevInitialize (
>>     VOID
>>     )
>>   {
>> -  CPUID_MEMORY_ENCRYPTION_INFO_EBX  Ebx;
>>     UINT64                            EncryptionMask;
>>     RETURN_STATUS                     PcdStatus;
>>   
>> @@ -43,15 +40,10 @@ AmdSevInitialize (
>>       return;
>>     }
>>   
>> -  //
>> -  // CPUID Fn8000_001F[EBX] Bit 0:5 (memory encryption bit position)
>> -  //
>> -  AsmCpuid (CPUID_MEMORY_ENCRYPTION_INFO, NULL, &Ebx.Uint32, NULL, NULL);
>> -  EncryptionMask = LShiftU64 (1, Ebx.Bits.PtePosBits);
>> -
>>     //
>>     // Set Memory Encryption Mask PCD
>>     //
>> +  EncryptionMask = MemEncryptSevGetEncryptionMask ();
>>     PcdStatus = PcdSet64S (PcdPteMemoryEncryptionAddressOrMask, EncryptionMask);
>>     ASSERT_RETURN_ERROR (PcdStatus);
>>   
>> diff --git a/OvmfPkg/Library/BaseMemEncryptSevLib/DxeMemEncryptSevLibInternal.c b/OvmfPkg/Library/BaseMemEncryptSevLib/DxeMemEncryptSevLibInternal.c
>> new file mode 100644
>> index 000000000000..2816f859a0c4
>> --- /dev/null
>> +++ b/OvmfPkg/Library/BaseMemEncryptSevLib/DxeMemEncryptSevLibInternal.c
>> @@ -0,0 +1,145 @@
>> +/** @file
>> +
>> +  Secure Encrypted Virtualization (SEV) library helper function
>> +
>> +  Copyright (c) 2017 - 2020, AMD Incorporated. All rights reserved.<BR>
>> +
>> +  SPDX-License-Identifier: BSD-2-Clause-Patent
>> +
>> +**/
>> +
>> +#include <Library/BaseLib.h>
>> +#include <Library/DebugLib.h>
>> +#include <Library/MemEncryptSevLib.h>
>> +#include <Library/PcdLib.h>
>> +#include <Register/Amd/Cpuid.h>
>> +#include <Register/Amd/Msr.h>
>> +#include <Register/Cpuid.h>
>> +#include <Uefi/UefiBaseType.h>
>> +
>> +STATIC BOOLEAN mSevStatus = FALSE;
>> +STATIC BOOLEAN mSevEsStatus = FALSE;
>> +STATIC BOOLEAN mSevStatusChecked = FALSE;
>> +
>> +STATIC UINT64  mSevEncryptionMask = 0;
>> +STATIC BOOLEAN mSevEncryptionMaskSaved = FALSE;
>> +
>> +/**
>> +  Reads and sets the status of SEV features.
>> +
>> +  **/
>> +STATIC
>> +VOID
>> +EFIAPI
>> +InternalMemEncryptSevStatus (
>> +  VOID
>> +  )
>> +{
>> +  UINT32                            RegEax;
>> +  MSR_SEV_STATUS_REGISTER           Msr;
>> +  CPUID_MEMORY_ENCRYPTION_INFO_EAX  Eax;
>> +  BOOLEAN                           ReadSevMsr;
>> +  UINT64                            EncryptionMask;
>> +
>> +  ReadSevMsr = FALSE;
>> +
>> +  EncryptionMask = PcdGet64 (PcdPteMemoryEncryptionAddressOrMask);
>> +  if (EncryptionMask != 0) {
>> +    //
>> +    // The MSR has been read before, so it is safe to read it again and avoid
>> +    // having to validate the CPUID information.
>> +    //
>> +    ReadSevMsr = TRUE;
>> +  } else {
>> +    //
>> +    // Check if memory encryption leaf exist
>> +    //
>> +    AsmCpuid (CPUID_EXTENDED_FUNCTION, &RegEax, NULL, NULL, NULL);
>> +    if (RegEax >= CPUID_MEMORY_ENCRYPTION_INFO) {
>> +      //
>> +      // CPUID Fn8000_001F[EAX] Bit 1 (Sev supported)
>> +      //
>> +      AsmCpuid (CPUID_MEMORY_ENCRYPTION_INFO, &Eax.Uint32, NULL, NULL, NULL);
>> +
>> +      if (Eax.Bits.SevBit) {
>> +        ReadSevMsr = TRUE;
>> +      }
>> +    }
>> +  }
>> +
>> +  if (ReadSevMsr) {
>> +    //
>> +    // Check MSR_0xC0010131 Bit 0 (Sev Enabled)
>> +    //
>> +    Msr.Uint32 = AsmReadMsr32 (MSR_SEV_STATUS);
>> +    if (Msr.Bits.SevBit) {
>> +      mSevStatus = TRUE;
>> +    }
>> +
>> +    //
>> +    // Check MSR_0xC0010131 Bit 1 (Sev-Es Enabled)
>> +    //
>> +    if (Msr.Bits.SevEsBit) {
>> +      mSevEsStatus = TRUE;
>> +    }
>> +  }
>> +
>> +  mSevStatusChecked = TRUE;
>> +}
>> +
>> +/**
>> +  Returns a boolean to indicate whether SEV-ES is enabled.
>> +
>> +  @retval TRUE           SEV-ES is enabled
>> +  @retval FALSE          SEV-ES is not enabled
>> +**/
>> +BOOLEAN
>> +EFIAPI
>> +MemEncryptSevEsIsEnabled (
>> +  VOID
>> +  )
>> +{
>> +  if (!mSevStatusChecked) {
>> +    InternalMemEncryptSevStatus ();
>> +  }
>> +
>> +  return mSevEsStatus;
>> +}
>> +
>> +/**
>> +  Returns a boolean to indicate whether SEV is enabled.
>> +
>> +  @retval TRUE           SEV is enabled
>> +  @retval FALSE          SEV is not enabled
>> +**/
>> +BOOLEAN
>> +EFIAPI
>> +MemEncryptSevIsEnabled (
>> +  VOID
>> +  )
>> +{
>> +  if (!mSevStatusChecked) {
>> +    InternalMemEncryptSevStatus ();
>> +  }
>> +
>> +  return mSevStatus;
>> +}
>> +
>> +/**
>> +  Returns the SEV encryption mask.
>> +
>> +  @return  The SEV pagtable encryption mask
>> +**/
>> +UINT64
>> +EFIAPI
>> +MemEncryptSevGetEncryptionMask (
>> +  VOID
>> +  )
>> +{
>> +  if (!mSevEncryptionMaskSaved) {
>> +    mSevEncryptionMask = PcdGet64 (PcdPteMemoryEncryptionAddressOrMask);
>> +    mSevEncryptionMaskSaved = TRUE;
>> +  }
>> +
>> +  return mSevEncryptionMask;
>> +}
>> diff --git a/OvmfPkg/Library/BaseMemEncryptSevLib/MemEncryptSevLibInternal.c b/OvmfPkg/Library/BaseMemEncryptSevLib/MemEncryptSevLibInternal.c
>> index 02b8eb225d81..ec6d02eaefd0 100644
>> --- a/OvmfPkg/Library/BaseMemEncryptSevLib/MemEncryptSevLibInternal.c
>> +++ b/OvmfPkg/Library/BaseMemEncryptSevLib/MemEncryptSevLibInternal.c
>> @@ -2,7 +2,7 @@
>>   
>>     Secure Encrypted Virtualization (SEV) library helper function
>>   
>> -  Copyright (c) 2017, AMD Incorporated. All rights reserved.<BR>
>> +  Copyright (c) 2017 - 2020, AMD Incorporated. All rights reserved.<BR>
>>   
>>     SPDX-License-Identifier: BSD-2-Clause-Patent
>>   
>> @@ -19,95 +19,6 @@
>>   #include <Register/SmramSaveStateMap.h>
>>   #include <Uefi/UefiBaseType.h>
>>   
>> -STATIC BOOLEAN mSevStatus = FALSE;
>> -STATIC BOOLEAN mSevEsStatus = FALSE;
>> -STATIC BOOLEAN mSevStatusChecked = FALSE;
>> -
>> -/**
>> -  Reads and sets the status of SEV features.
>> -
>> -  **/
>> -STATIC
>> -VOID
>> -EFIAPI
>> -InternalMemEncryptSevStatus (
>> -  VOID
>> -  )
>> -{
>> -  UINT32                            RegEax;
>> -  MSR_SEV_STATUS_REGISTER           Msr;
>> -  CPUID_MEMORY_ENCRYPTION_INFO_EAX  Eax;
>> -
>> -  //
>> -  // Check if memory encryption leaf exist
>> -  //
>> -  AsmCpuid (CPUID_EXTENDED_FUNCTION, &RegEax, NULL, NULL, NULL);
>> -  if (RegEax >= CPUID_MEMORY_ENCRYPTION_INFO) {
>> -    //
>> -    // CPUID Fn8000_001F[EAX] Bit 1 (Sev supported)
>> -    //
>> -    AsmCpuid (CPUID_MEMORY_ENCRYPTION_INFO, &Eax.Uint32, NULL, NULL, NULL);
>> -
>> -    if (Eax.Bits.SevBit) {
>> -      //
>> -      // Check MSR_0xC0010131 Bit 0 (Sev Enabled)
>> -      //
>> -      Msr.Uint32 = AsmReadMsr32 (MSR_SEV_STATUS);
>> -      if (Msr.Bits.SevBit) {
>> -        mSevStatus = TRUE;
>> -      }
>> -
>> -      //
>> -      // Check MSR_0xC0010131 Bit 1 (Sev-Es Enabled)
>> -      //
>> -      if (Msr.Bits.SevEsBit) {
>> -        mSevEsStatus = TRUE;
>> -      }
>> -    }
>> -  }
>> -
>> -  mSevStatusChecked = TRUE;
>> -}
>> -
>> -/**
>> -  Returns a boolean to indicate whether SEV-ES is enabled.
>> -
>> -  @retval TRUE           SEV-ES is enabled
>> -  @retval FALSE          SEV-ES is not enabled
>> -**/
>> -BOOLEAN
>> -EFIAPI
>> -MemEncryptSevEsIsEnabled (
>> -  VOID
>> -  )
>> -{
>> -  if (!mSevStatusChecked) {
>> -    InternalMemEncryptSevStatus ();
>> -  }
>> -
>> -  return mSevEsStatus;
>> -}
>> -
>> -/**
>> -  Returns a boolean to indicate whether SEV is enabled.
>> -
>> -  @retval TRUE           SEV is enabled
>> -  @retval FALSE          SEV is not enabled
>> -**/
>> -BOOLEAN
>> -EFIAPI
>> -MemEncryptSevIsEnabled (
>> -  VOID
>> -  )
>> -{
>> -  if (!mSevStatusChecked) {
>> -    InternalMemEncryptSevStatus ();
>> -  }
>> -
>> -  return mSevStatus;
>> -}
>> -
>> -
>>   /**
>>     Locate the page range that covers the initial (pre-SMBASE-relocation) SMRAM
>>     Save State Map.
>> diff --git a/OvmfPkg/Library/BaseMemEncryptSevLib/PeiMemEncryptSevLibInternal.c b/OvmfPkg/Library/BaseMemEncryptSevLib/PeiMemEncryptSevLibInternal.c
>> new file mode 100644
>> index 000000000000..e2fd109d120f
>> --- /dev/null
>> +++ b/OvmfPkg/Library/BaseMemEncryptSevLib/PeiMemEncryptSevLibInternal.c
>> @@ -0,0 +1,159 @@
>> +/** @file
>> +
>> +  Secure Encrypted Virtualization (SEV) library helper function
>> +
>> +  Copyright (c) 2020, AMD Incorporated. All rights reserved.<BR>
>> +
>> +  SPDX-License-Identifier: BSD-2-Clause-Patent
>> +
>> +**/
>> +
>> +#include <Library/BaseLib.h>
>> +#include <Library/DebugLib.h>
>> +#include <Library/MemEncryptSevLib.h>
>> +#include <Library/PcdLib.h>
>> +#include <Register/Amd/Cpuid.h>
>> +#include <Register/Amd/Msr.h>
>> +#include <Register/Cpuid.h>
>> +#include <Uefi/UefiBaseType.h>
>> +
>> +STATIC BOOLEAN mSevStatus = FALSE;
>> +STATIC BOOLEAN mSevEsStatus = FALSE;
>> +STATIC BOOLEAN mSevStatusChecked = FALSE;
>> +
>> +STATIC UINT64  mSevEncryptionMask = 0;
>> +STATIC BOOLEAN mSevEncryptionMaskSaved = FALSE;
>> +
>> +/**
>> +  Reads and sets the status of SEV features.
>> +
>> +  **/
>> +STATIC
>> +VOID
>> +EFIAPI
>> +InternalMemEncryptSevStatus (
>> +  VOID
>> +  )
>> +{
>> +  UINT32                            RegEax;
>> +  MSR_SEV_STATUS_REGISTER           Msr;
>> +  CPUID_MEMORY_ENCRYPTION_INFO_EAX  Eax;
>> +  BOOLEAN                           ReadSevMsr;
>> +  SEC_SEV_ES_WORK_AREA              *SevEsWorkArea;
>> +
>> +  ReadSevMsr = FALSE;
>> +
>> +  SevEsWorkArea = (SEC_SEV_ES_WORK_AREA *) FixedPcdGet32 (PcdSevEsWorkAreaBase);
>> +  if (SevEsWorkArea != NULL && SevEsWorkArea->EncryptionMask != 0) {
>> +    //
>> +    // The MSR has been read before, so it is safe to read it again and avoid
>> +    // having to validate the CPUID information.
>> +    //
>> +    ReadSevMsr = TRUE;
>> +  } else {
>> +    //
>> +    // Check if memory encryption leaf exist
>> +    //
>> +    AsmCpuid (CPUID_EXTENDED_FUNCTION, &RegEax, NULL, NULL, NULL);
>> +    if (RegEax >= CPUID_MEMORY_ENCRYPTION_INFO) {
>> +      //
>> +      // CPUID Fn8000_001F[EAX] Bit 1 (Sev supported)
>> +      //
>> +      AsmCpuid (CPUID_MEMORY_ENCRYPTION_INFO, &Eax.Uint32, NULL, NULL, NULL);
>> +
>> +      if (Eax.Bits.SevBit) {
>> +        ReadSevMsr = TRUE;
>> +      }
>> +    }
>> +  }
>> +
>> +  if (ReadSevMsr) {
>> +    //
>> +    // Check MSR_0xC0010131 Bit 0 (Sev Enabled)
>> +    //
>> +    Msr.Uint32 = AsmReadMsr32 (MSR_SEV_STATUS);
>> +    if (Msr.Bits.SevBit) {
>> +      mSevStatus = TRUE;
>> +    }
>> +
>> +    //
>> +    // Check MSR_0xC0010131 Bit 1 (Sev-Es Enabled)
>> +    //
>> +    if (Msr.Bits.SevEsBit) {
>> +      mSevEsStatus = TRUE;
>> +    }
>> +  }
>> +
>> +  mSevStatusChecked = TRUE;
>> +}
>> +
>> +/**
>> +  Returns a boolean to indicate whether SEV-ES is enabled.
>> +
>> +  @retval TRUE           SEV-ES is enabled
>> +  @retval FALSE          SEV-ES is not enabled
>> +**/
>> +BOOLEAN
>> +EFIAPI
>> +MemEncryptSevEsIsEnabled (
>> +  VOID
>> +  )
>> +{
>> +  if (!mSevStatusChecked) {
>> +    InternalMemEncryptSevStatus ();
>> +  }
>> +
>> +  return mSevEsStatus;
>> +}
>> +
>> +/**
>> +  Returns a boolean to indicate whether SEV is enabled.
>> +
>> +  @retval TRUE           SEV is enabled
>> +  @retval FALSE          SEV is not enabled
>> +**/
>> +BOOLEAN
>> +EFIAPI
>> +MemEncryptSevIsEnabled (
>> +  VOID
>> +  )
>> +{
>> +  if (!mSevStatusChecked) {
>> +    InternalMemEncryptSevStatus ();
>> +  }
>> +
>> +  return mSevStatus;
>> +}
>> +
>> +/**
>> +  Returns the SEV encryption mask.
>> +
>> +  @return  The SEV pagtable encryption mask
>> +**/
>> +UINT64
>> +EFIAPI
>> +MemEncryptSevGetEncryptionMask (
>> +  VOID
>> +  )
>> +{
>> +  if (!mSevEncryptionMaskSaved) {
>> +    SEC_SEV_ES_WORK_AREA  *SevEsWorkArea;
>> +
>> +    SevEsWorkArea = (SEC_SEV_ES_WORK_AREA *) FixedPcdGet32 (PcdSevEsWorkAreaBase);
>> +    if (SevEsWorkArea != NULL) {
>> +      mSevEncryptionMask = SevEsWorkArea->EncryptionMask;
>> +    } else {
>> +      CPUID_MEMORY_ENCRYPTION_INFO_EBX  Ebx;
>> +
>> +      //
>> +      // CPUID Fn8000_001F[EBX] Bit 0:5 (memory encryption bit position)
>> +      //
>> +      AsmCpuid (CPUID_MEMORY_ENCRYPTION_INFO, NULL, &Ebx.Uint32, NULL, NULL);
>> +      mSevEncryptionMask = LShiftU64 (1, Ebx.Bits.PtePosBits);
>> +    }
>> +
>> +    mSevEncryptionMaskSaved = TRUE;
>> +  }
>> +
>> +  return mSevEncryptionMask;
>> +}
>> diff --git a/OvmfPkg/Library/BaseMemEncryptSevLib/X64/VirtualMemory.c b/OvmfPkg/Library/BaseMemEncryptSevLib/X64/VirtualMemory.c
>> index 5e110c84ff81..6422bc53bd5d 100644
>> --- a/OvmfPkg/Library/BaseMemEncryptSevLib/X64/VirtualMemory.c
>> +++ b/OvmfPkg/Library/BaseMemEncryptSevLib/X64/VirtualMemory.c
>> @@ -3,7 +3,7 @@
>>     Virtual Memory Management Services to set or clear the memory encryption bit
>>   
>>     Copyright (c) 2006 - 2018, Intel Corporation. All rights reserved.<BR>
>> -  Copyright (c) 2017, AMD Incorporated. All rights reserved.<BR>
>> +  Copyright (c) 2017 - 2020, AMD Incorporated. All rights reserved.<BR>
>>   
>>     SPDX-License-Identifier: BSD-2-Clause-Patent
>>   
>> @@ -12,6 +12,7 @@
>>   **/
>>   
>>   #include <Library/CpuLib.h>
>> +#include <Library/MemEncryptSevLib.h>
>>   #include <Register/Amd/Cpuid.h>
>>   #include <Register/Cpuid.h>
>>   
>> @@ -39,17 +40,12 @@ GetMemEncryptionAddressMask (
>>     )
>>   {
>>     UINT64                            EncryptionMask;
>> -  CPUID_MEMORY_ENCRYPTION_INFO_EBX  Ebx;
>>   
>>     if (mAddressEncMaskChecked) {
>>       return mAddressEncMask;
>>     }
>>   
>> -  //
>> -  // CPUID Fn8000_001F[EBX] Bit 0:5 (memory encryption bit position)
>> -  //
>> -  AsmCpuid (CPUID_MEMORY_ENCRYPTION_INFO, NULL, &Ebx.Uint32, NULL, NULL);
>> -  EncryptionMask = LShiftU64 (1, Ebx.Bits.PtePosBits);
>> +  EncryptionMask = MemEncryptSevGetEncryptionMask ();
>>   
>>     mAddressEncMask = EncryptionMask & PAGING_1G_ADDRESS_MASK_64;
>>     mAddressEncMaskChecked = TRUE;
>> @@ -289,8 +285,7 @@ SetPageTablePoolReadOnly (
>>     LevelSize[3] = SIZE_1GB;
>>     LevelSize[4] = SIZE_512GB;
>>   
>> -  AddressEncMask  = GetMemEncryptionAddressMask() &
>> -                    PAGING_1G_ADDRESS_MASK_64;
>> +  AddressEncMask  = GetMemEncryptionAddressMask();
>>     PageTable       = (UINT64 *)(UINTN)PageTableBase;
>>     PoolUnitSize    = PAGE_TABLE_POOL_UNIT_SIZE;
>>   
>> @@ -437,7 +432,7 @@ Split1GPageTo2M (
>>   
>>     AddressEncMask = GetMemEncryptionAddressMask ();
>>     ASSERT (PageDirectoryEntry != NULL);
>> -  ASSERT (*PageEntry1G & GetMemEncryptionAddressMask ());
>> +  ASSERT (*PageEntry1G & AddressEncMask);
>>     //
>>     // Fill in 1G page entry.
>>     //
>> diff --git a/OvmfPkg/PlatformPei/AmdSev.c b/OvmfPkg/PlatformPei/AmdSev.c
>> index 4a515a484720..954d53eba4e8 100644
>> --- a/OvmfPkg/PlatformPei/AmdSev.c
>> +++ b/OvmfPkg/PlatformPei/AmdSev.c
>> @@ -1,7 +1,7 @@
>>   /**@file
>>     Initialize Secure Encrypted Virtualization (SEV) support
>>   
>> -  Copyright (c) 2017, Advanced Micro Devices. All rights reserved.<BR>
>> +  Copyright (c) 2017 - 2020, Advanced Micro Devices. All rights reserved.<BR>
>>   
>>     SPDX-License-Identifier: BSD-2-Clause-Patent
>>   
>> @@ -17,9 +17,7 @@
>>   #include <Library/MemoryAllocationLib.h>
>>   #include <Library/PcdLib.h>
>>   #include <PiPei.h>
>> -#include <Register/Amd/Cpuid.h>
>>   #include <Register/Amd/Msr.h>
>> -#include <Register/Cpuid.h>
>>   #include <Register/Intel/SmramSaveStateMap.h>
>>   
>>   #include "Platform.h"
>> @@ -116,7 +114,6 @@ AmdSevInitialize (
>>     VOID
>>     )
>>   {
>> -  CPUID_MEMORY_ENCRYPTION_INFO_EBX  Ebx;
>>     UINT64                            EncryptionMask;
>>     RETURN_STATUS                     PcdStatus;
>>   
>> @@ -127,15 +124,10 @@ AmdSevInitialize (
>>       return;
>>     }
>>   
>> -  //
>> -  // CPUID Fn8000_001F[EBX] Bit 0:5 (memory encryption bit position)
>> -  //
>> -  AsmCpuid (CPUID_MEMORY_ENCRYPTION_INFO, NULL, &Ebx.Uint32, NULL, NULL);
>> -  EncryptionMask = LShiftU64 (1, Ebx.Bits.PtePosBits);
>> -
>>     //
>>     // Set Memory Encryption Mask PCD
>>     //
>> +  EncryptionMask = MemEncryptSevGetEncryptionMask ();
>>     PcdStatus = PcdSet64S (PcdPteMemoryEncryptionAddressOrMask, EncryptionMask);
>>     ASSERT_RETURN_ERROR (PcdStatus);
>>   
>> diff --git a/OvmfPkg/XenPlatformPei/AmdSev.c b/OvmfPkg/XenPlatformPei/AmdSev.c
>> index 7ebbb5cc1fd2..4ed448632ae2 100644
>> --- a/OvmfPkg/XenPlatformPei/AmdSev.c
>> +++ b/OvmfPkg/XenPlatformPei/AmdSev.c
>> @@ -1,7 +1,7 @@
>>   /**@file
>>     Initialize Secure Encrypted Virtualization (SEV) support
>>   
>> -  Copyright (c) 2017, Advanced Micro Devices. All rights reserved.<BR>
>> +  Copyright (c) 2017 - 2020, Advanced Micro Devices. All rights reserved.<BR>
>>     Copyright (c) 2019, Citrix Systems, Inc.
>>   
>>     SPDX-License-Identifier: BSD-2-Clause-Patent
>> @@ -14,8 +14,6 @@
>>   #include <Library/MemEncryptSevLib.h>
>>   #include <Library/PcdLib.h>
>>   #include <PiPei.h>
>> -#include <Register/Amd/Cpuid.h>
>> -#include <Register/Cpuid.h>
>>   
>>   #include "Platform.h"
>>   
>> @@ -30,7 +28,6 @@ AmdSevInitialize (
>>     VOID
>>     )
>>   {
>> -  CPUID_MEMORY_ENCRYPTION_INFO_EBX  Ebx;
>>     UINT64                            EncryptionMask;
>>     RETURN_STATUS                     PcdStatus;
>>   
>> @@ -41,15 +38,10 @@ AmdSevInitialize (
>>       return;
>>     }
>>   
>> -  //
>> -  // CPUID Fn8000_001F[EBX] Bit 0:5 (memory encryption bit position)
>> -  //
>> -  AsmCpuid (CPUID_MEMORY_ENCRYPTION_INFO, NULL, &Ebx.Uint32, NULL, NULL);
>> -  EncryptionMask = LShiftU64 (1, Ebx.Bits.PtePosBits);
>> -
>>     //
>>     // Set Memory Encryption Mask PCD
>>     //
>> +  EncryptionMask = MemEncryptSevGetEncryptionMask ();
>>     PcdStatus = PcdSet64S (PcdPteMemoryEncryptionAddressOrMask, EncryptionMask);
>>     ASSERT_RETURN_ERROR (PcdStatus);
>>   
>> diff --git a/OvmfPkg/ResetVector/Ia32/PageTables64.asm b/OvmfPkg/ResetVector/Ia32/PageTables64.asm
>> index b08f31157cbf..8c0d432050df 100644
>> --- a/OvmfPkg/ResetVector/Ia32/PageTables64.asm
>> +++ b/OvmfPkg/ResetVector/Ia32/PageTables64.asm
>> @@ -145,13 +145,21 @@ GetSevEncBit:
>>   
>>       ; The encryption bit position is always above 31
>>       sub       ebx, 32
>> -    jns       SevExit
>> +    jns       SevSaveMask
>>   
>>       ; Encryption bit was reported as 31 or below, enter a HLT loop
>>   SevEncBitLowHlt:
>>       hlt
>>       jmp       SevEncBitLowHlt
>>   
>> +SevSaveMask:
>> +    xor       edx, edx
>> +    bts       edx, ebx
>> +
>> +    mov       dword[SEV_ES_WORK_AREA_ENC_MASK], 0
>> +    mov       dword[SEV_ES_WORK_AREA_ENC_MASK + 4], edx
>> +    jmp       SevExit
>> +
>>   NoSev:
>>       ;
>>       ; Perform an SEV-ES sanity check by seeing if a #VC exception occurred.
>> diff --git a/OvmfPkg/ResetVector/ResetVector.nasmb b/OvmfPkg/ResetVector/ResetVector.nasmb
>> index d3aa87982959..5fbacaed5f9d 100644
>> --- a/OvmfPkg/ResetVector/ResetVector.nasmb
>> +++ b/OvmfPkg/ResetVector/ResetVector.nasmb
>> @@ -74,6 +74,7 @@
>>     %define GHCB_SIZE (FixedPcdGet32 (PcdOvmfSecGhcbSize))
>>     %define SEV_ES_WORK_AREA (FixedPcdGet32 (PcdSevEsWorkAreaBase))
>>     %define SEV_ES_WORK_AREA_RDRAND (FixedPcdGet32 (PcdSevEsWorkAreaBase) + 8)
>> +  %define SEV_ES_WORK_AREA_ENC_MASK (FixedPcdGet32 (PcdSevEsWorkAreaBase) + 16)
>>     %define SEV_ES_VC_TOP_OF_STACK (FixedPcdGet32 (PcdOvmfSecPeiTempRamBase) + FixedPcdGet32 (PcdOvmfSecPeiTempRamSize))
>>   %include "Ia32/Flat32ToFlat64.asm"
>>   %include "Ia32/PageTables64.asm"
>>
>