Re: [PATCH v11 00/32] Add AMD Secure Nested Paging (SEV-SNP) support

Brijesh Singh

Hi Ray and Rahul,

Gentle ping. Could you please Ack or R-b the files touched in UefiCpuPkg?


On 10/29/21 9:52 AM, Brijesh Singh wrote:
Hi Jiewen,

I have not heard anything back from UefiCpuPkg maintainer yet, I will
send another gentle ping on Monday again and hope maintainer get to it.


On 10/29/21 7:26 AM, Yao, Jiewen wrote:
Hi Brijesh
Have you got R-B from UefiCpuPkg maintainer?

-----Original Message-----
From: Brijesh Singh <brijesh.singh@...>
Sent: Monday, October 25, 2021 7:54 AM
To:; Yao, Jiewen <jiewen.yao@...>
Cc: brijesh.singh@...; James Bottomley <jejb@...>; Xu, Min M
<min.m.xu@...>; Tom Lendacky <thomas.lendacky@...>; Justen,
Jordan L <jordan.l.justen@...>; Ard Biesheuvel
<ardb+tianocore@...>; Erdem Aktas <erdemaktas@...>;
Michael Roth <Michael.Roth@...>; Gerd Hoffmann <kraxel@...>
Subject: Re: [edk2-devel] [PATCH v11 00/32] Add AMD Secure Nested Paging
(SEV-SNP) support

Thank Jiewen,

I have ping'ed UefiCpuPkg maintainer (Ray and Rahul) on every patch
which touches the UefiCpuPkg. If maintainer wants me to rework on
something then I will work accordingly. If they are okay with v11 then
now the merge will create a conflict (due to the TDX patches merge
commit). I have rebased my series to the recent master and have pushed
it here:;;sdata=vF9b44WpM45fiDCF4%2BdwvKCcoPHr0bj6xzTCi4%2BlR2s%3D&amp;reserved=0. I can post the
series if you prefer it.


On 10/23/21 8:46 PM, Yao, Jiewen via wrote:
Yes. I will try my best to merge.

I checked the patch set but I did not find the "R-B" from UefiCpuPkg
maintainer. Neither from email nor from you v11.
Did I miss something?

Thank you
Yao Jiewen

-----Original Message-----
From: Brijesh Singh <brijesh.singh@...>
Sent: Saturday, October 23, 2021 12:13 PM
Cc: James Bottomley <jejb@...>; Xu, Min M
Yao, Jiewen <jiewen.yao@...>; Tom Lendacky
<thomas.lendacky@...>; Justen, Jordan L <jordan.l.justen@...>;
Ard Biesheuvel <ardb+tianocore@...>; Erdem Aktas
<erdemaktas@...>; Michael Roth <Michael.Roth@...>; Gerd
Hoffmann <kraxel@...>; Brijesh Singh <brijesh.singh@...>
Subject: [PATCH v11 00/32] Add AMD Secure Nested Paging (SEV-SNP)
Hi Gerd and Jiewen,

CI was a bit unstable during my v10 submission, so, I was not able to
run it to the completion. Finally, I managed to get the CI going,
and it reported few Windows 32-bit build errors. The v11 fixes those build
errors. Please consider this for the merge.

Thank you so much for all your support in reviewing the series.

SEV-SNP builds upon existing SEV and SEV-ES functionality while adding
new hardware-based memory protections. SEV-SNP adds strong memory
protection to help prevent malicious hypervisor-based attacks like data
replay, memory re-mapping and more in order to create an isolated memory
encryption environment.

This series provides the basic building blocks to support booting the SEV-SNP
VMs, it does not cover all the security enhancement introduced by the SEV-
such as interrupt protection.

Many of the integrity guarantees of SEV-SNP are enforced through a new
structure called the Reverse Map Table (RMP). Adding a new page to SEV-SNP
VM requires a 2-step process. First, the hypervisor assigns a page to the
guest using the new RMPUPDATE instruction. This transitions the page to
guest-invalid. Second, the guest validates the page using the new PVALIDATE
instruction. The SEV-SNP VMs can use the new "Page State Change Request
defined in the GHCB specification to ask hypervisor to add or remove page
from the RMP table.

Each page assigned to the SEV-SNP VM can either be validated or unvalidated,
as indicated by the Validated flag in the page's RMP entry. There are two
approaches that can be taken for the page validation: Pre-validation and
Lazy Validation.

Under pre-validation, the pages are validated prior to first use. And under
lazy validation, pages are validated when first accessed. An access to a
unvalidated page results in a #VC exception, at which time the exception
handler may validate the page. Lazy validation requires careful tracking of
the validated pages to avoid validating the same GPA more than once. The
recently introduced "Unaccepted" memory type can be used to communicate
unvalidated memory ranges to the Guest OS.

At this time we only support the pre-validation. OVMF detects all the
system RAM in the PEI phase. When SEV-SNP is enabled, the memory is
before it is made available to the EDK2 core.

Now that series contains all the basic support required to launch SEV-SNP
guest. We are still missing the Interrupt security feature provided by the
SNP. The feature will be added after the base support is accepted.

Additional resources
SEV-SNP whitepaper;;sdata=9sOcgACg2M6QuveVuAf8FZFv5rb9i36svspZsudpkdM%3D&amp;reserved=0

APM 2:;;sdata=9sOcgACg2M6QuveVuAf8FZFv5rb9i36svspZsudpkdM%3D&amp;reserved=0;data=04%7C01%7
uI0k8QcLDTbpJiTplg%3D&amp;reserved=0 (section 15.36)
The complete source is available at;;sdata=fjvSca7meCrd6%2FDBlefYmRIqYS8GEcwbR6819yb7rdw%3D&amp;reserved=0
GHCB spec:
SEV-SNP firmware specification:;;sdata=9sOcgACg2M6QuveVuAf8FZFv5rb9i36svspZsudpkdM%3D&amp;reserved=0;data=04%7C01%7
Change since v10:
* fix 'unresolved external symbol __allshl' link error when building I32 for

Changes since v9:
* Move CCAttrs Pcd define in MdePkg
* Add comment to indicate that allocating the identity map PT is temporary
we get lazy validation

Changes since v8:
* drop the generic metadata and make it specific to SEV.

Changes since v7:
* Move SEV specific changes in MpLib in AmdSev file
* Update the GHCB register function to not restore the GHCB MSR because
we were already in the MSR protocol mode.
* Drop the SNP name from PcdSnpSecPreValidate.
* Add new section for GHCB memory in the OVMF metadata.

Change since v6:
* Drop the SNP boot block GUID and switch to using the Metadata guided
proposed by Min in TDX series.
* Exclude the GHCB page from the pre-validated region. It simplifies the
vector code where we do not need to unvalidate the GHCB page.
* Now that GHCB page is not validated so move the VMPL check from reset
code to the MemEncryptSevLib on the first page validation.
* Introduce the ConfidentialComputingGuestAttr PCD to communicate which
memory encryption is active so that MpInitLib can make use of it.
* Drop the SEVES specific PCD as the information can be communicated via
the ConfidentialComputingGuestAttr.
* Move the SNP specific AP creation function in AmdSev.c.
* Define the SNP Blob GUID in a new file.

Change since v5:
* When possible use the CPUID value from CPUID page
* Move the SEV specific functions from SecMain.c in AmdSev.c
* Rebase to the latest code
* Add the review feedback from Yao.

Change since v4:
* Use the correct MSR for the SEV_STATUS
* Add VMPL-0 check

Change since v3:
* ResetVector: move all SEV specific code in AmdSev.asm and add macros to
the code readable.
* Drop extending the EsWorkArea to contain SNP specific state.
* Drop the GhcbGpa library and call the VmgExit directly to register GHCB
* Install the CC blob config table from AmdSevDxe instead of extending the
AmdSev/SecretsDxe for it.
* Add the separate PCDs for the SNP Secrets.

Changes since v2:
* Add support for the AP creation.
* Use the module-scoping override to make AmdSevDxe use the IO port for
* Use the reserved memory type for CPUID and Secrets page.
Changes since v1:
* Drop the interval tree support to detect the pre-validated overlap region.
* Use an array to keep track of pre-validated regions.
* Add support to query the Hypervisor feature and verify that SNP feature is
* Introduce MemEncryptSevClearMmioPageEncMask() to clear the C-bit
MMIO ranges.
* Pull the SevSecretDxe and SevSecretPei into OVMF package build.
* Extend the SevSecretDxe to expose confidential computing blob location
EFI configuration table.

Brijesh Singh (28):
OvmfPkg/SecMain: move SEV specific routines in AmdSev.c
UefiCpuPkg/MpInitLib: move SEV specific routines in AmdSev.c
OvmfPkg/ResetVector: move clearing GHCB in SecMain
OvmfPkg/ResetVector: introduce SEV metadata descriptor for VMM use
OvmfPkg: reserve SNP secrets page
OvmfPkg: reserve CPUID page
OvmfPkg/ResetVector: pre-validate the data pages used in SEC phase
OvmfPkg/MemEncryptSevLib: add MemEncryptSevSnpEnabled()
OvmfPkg/SecMain: register GHCB gpa for the SEV-SNP guest
OvmfPkg/PlatformPei: register GHCB gpa for the SEV-SNP guest
OvmfPkg/AmdSevDxe: do not use extended PCI config space
OvmfPkg/MemEncryptSevLib: add support to validate system RAM
OvmfPkg/MemEncryptSevLib: add function to check the VMPL0
OvmfPkg/BaseMemEncryptSevLib: skip the pre-validated system RAM
OvmfPkg/MemEncryptSevLib: add support to validate > 4GB memory in PEI
OvmfPkg/SecMain: validate the memory used for decompressing Fv
OvmfPkg/PlatformPei: validate the system RAM when SNP is active
UefiCpuPkg: Define ConfidentialComputingGuestAttr
OvmfPkg/PlatformPei: set PcdConfidentialComputingAttr when SEV is
UefiCpuPkg/MpInitLib: use PcdConfidentialComputingAttr to check SEV
UefiCpuPkg: add PcdGhcbHypervisorFeatures
OvmfPkg/PlatformPei: set the Hypervisor Features PCD
MdePkg/GHCB: increase the GHCB protocol max version
UefiCpuPkg/MpLib: add support to register GHCB GPA when SEV-SNP is
OvmfPkg/MemEncryptSevLib: change the page state in the RMP table
OvmfPkg/MemEncryptSevLib: skip page state change for Mmio address
OvmfPkg/PlatformPei: mark cpuid and secrets memory reserved in EFI map
OvmfPkg/AmdSev: expose the SNP reserved pages through configuration

Michael Roth (3):
OvmfPkg/ResetVector: use SEV-SNP-validated CPUID values
OvmfPkg/VmgExitLib: use SEV-SNP-validated CPUID values
UefiCpuPkg/MpInitLib: use BSP to do extended topology check

Tom Lendacky (1):
UefiCpuPkg/MpInitLib: Use SEV-SNP AP Creation NAE event to launch APs

MdePkg/MdePkg.dec | 4 +
OvmfPkg/OvmfPkg.dec | 18 +
UefiCpuPkg/UefiCpuPkg.dec | 5 +
OvmfPkg/AmdSev/AmdSevX64.dsc | 8 +-
OvmfPkg/Bhyve/BhyveX64.dsc | 5 +-
OvmfPkg/OvmfPkgIa32.dsc | 4 +
OvmfPkg/OvmfPkgIa32X64.dsc | 9 +-
OvmfPkg/OvmfPkgX64.dsc | 8 +-
OvmfPkg/OvmfXen.dsc | 5 +-
OvmfPkg/OvmfPkgX64.fdf | 6 +
OvmfPkg/AmdSevDxe/AmdSevDxe.inf | 7 +
.../DxeMemEncryptSevLib.inf | 3 +
.../PeiMemEncryptSevLib.inf | 7 +
.../SecMemEncryptSevLib.inf | 3 +
OvmfPkg/Library/VmgExitLib/SecVmgExitLib.inf | 2 +
OvmfPkg/Library/VmgExitLib/VmgExitLib.inf | 3 +
OvmfPkg/PlatformPei/PlatformPei.inf | 7 +
OvmfPkg/ResetVector/ResetVector.inf | 5 +
OvmfPkg/Sec/SecMain.inf | 4 +
UefiCpuPkg/Library/MpInitLib/DxeMpInitLib.inf | 6 +-
UefiCpuPkg/Library/MpInitLib/PeiMpInitLib.inf | 6 +-
.../Include/ConfidentialComputingGuestAttr.h | 25 +
MdePkg/Include/Register/Amd/Ghcb.h | 2 +-
.../Guid/ConfidentialComputingSevSnpBlob.h | 33 ++
OvmfPkg/Include/Library/MemEncryptSevLib.h | 26 +
.../X64/SnpPageStateChange.h | 36 ++
.../BaseMemEncryptSevLib/X64/VirtualMemory.h | 24 +
OvmfPkg/PlatformPei/Platform.h | 5 +
OvmfPkg/Sec/AmdSev.h | 95 ++++
UefiCpuPkg/Library/MpInitLib/MpLib.h | 93 ++++
OvmfPkg/AmdSevDxe/AmdSevDxe.c | 23 +
.../DxeMemEncryptSevLibInternal.c | 27 ++
.../Ia32/MemEncryptSevLib.c | 17 +
.../PeiMemEncryptSevLibInternal.c | 27 ++
.../SecMemEncryptSevLibInternal.c | 19 +
.../X64/DxeSnpSystemRamValidate.c | 40 ++
.../X64/PeiDxeVirtualMemory.c | 167 ++++++-
.../X64/PeiSnpSystemRamValidate.c | 127 +++++
.../X64/SecSnpSystemRamValidate.c | 82 ++++
.../X64/SnpPageStateChangeInternal.c | 294 ++++++++++++
OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c | 444
OvmfPkg/PlatformPei/AmdSev.c | 231 +++++++++
OvmfPkg/PlatformPei/MemDetect.c | 2 +
OvmfPkg/Sec/AmdSev.c | 298 ++++++++++++
OvmfPkg/Sec/SecMain.c | 158 +------
UefiCpuPkg/Library/MpInitLib/AmdSev.c | 239 ++++++++++
UefiCpuPkg/Library/MpInitLib/DxeMpLib.c | 16 +-
UefiCpuPkg/Library/MpInitLib/Ia32/AmdSev.c | 70 +++
UefiCpuPkg/Library/MpInitLib/MpLib.c | 345 +++++---------
UefiCpuPkg/Library/MpInitLib/PeiMpLib.c | 4 +-
UefiCpuPkg/Library/MpInitLib/X64/AmdSev.c | 261 ++++++++++
OvmfPkg/ | 5 +
OvmfPkg/ResetVector/Ia16/ResetVectorVtf0.asm | 17 +
OvmfPkg/ResetVector/Ia32/AmdSev.asm | 86 +++-
OvmfPkg/ResetVector/ResetVector.nasmb | 18 +
OvmfPkg/ResetVector/X64/OvmfSevMetadata.asm | 74 +++
UefiCpuPkg/Library/MpInitLib/ | 2 +
UefiCpuPkg/Library/MpInitLib/X64/AmdSev.nasm | 200 ++++++++
UefiCpuPkg/Library/MpInitLib/X64/MpFuncs.nasm | 100 +---
59 files changed, 3329 insertions(+), 528 deletions(-)
create mode 100644 MdePkg/Include/ConfidentialComputingGuestAttr.h
create mode 100644
create mode 100644
create mode 100644 OvmfPkg/Sec/AmdSev.h
create mode 100644
create mode 100644
create mode 100644
create mode 100644
create mode 100644 OvmfPkg/Sec/AmdSev.c
create mode 100644 UefiCpuPkg/Library/MpInitLib/AmdSev.c
create mode 100644 UefiCpuPkg/Library/MpInitLib/Ia32/AmdSev.c
create mode 100644 UefiCpuPkg/Library/MpInitLib/X64/AmdSev.c
create mode 100644 OvmfPkg/ResetVector/X64/OvmfSevMetadata.asm
create mode 100644 UefiCpuPkg/Library/MpInitLib/X64/AmdSev.nasm


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