Re: [RFC PATCH v4 00/27] Add AMD Secure Nested Paging (SEV-SNP) support

["Yao, Jiewen" <jiewen.yao@intel.com>]

Hi Brijesh
I reviewed the patch set. I have some basic questions.
Please help me understand before I post my comment

If a platform supports SEV-SNP, can we assume SEV-ES is supported?
Or is it a valid case that SecSnp==YES, SevEs==NO?

I am trying to understand how many cases we need support.
I think we want to support below:
+------------------------+
| SEV | SEV_ES | SEV_SNP |
+------------------------+
|  0  |   0    |    0    |
|  1  |   0    |    0    |
|  1  |   1    |    0    |
|  1  |   1    |    1    |
+------------------------+


Any other combination we need support? Such as below:
+------------------------+
| SEV | SEV_ES | SEV_SNP |
+------------------------+
|  0  |   1    |    0    |
|  0  |   0    |    1    |
|  0  |   1    |    1    |
|  1  |   0    |    1    |
+------------------------+


Thank you
Yao Jiewen

> -----Original Message-----
> From: Brijesh Singh <brijesh.singh@amd.com>
> Sent: Tuesday, June 29, 2021 1:42 AM
> To: devel@edk2.groups.io
> Cc: James Bottomley <jejb@linux.ibm.com>; Xu, Min M <min.m.xu@intel.com>;
> Yao, Jiewen <jiewen.yao@intel.com>; Tom Lendacky
> <thomas.lendacky@amd.com>; Justen, Jordan L <jordan.l.justen@intel.com>;
> Ard Biesheuvel <ardb+tianocore@kernel.org>; Laszlo Ersek
> <lersek@redhat.com>; Erdem Aktas <erdemaktas@google.com>; Dong, Eric
> <eric.dong@intel.com>; Ni, Ray <ray.ni@intel.com>; Kumar, Rahul1
> <rahul1.kumar@intel.com>; Kinney, Michael D <michael.d.kinney@intel.com>;
> Liming Gao <gaoliming@byosoft.com.cn>; Liu, Zhiguang
> <zhiguang.liu@intel.com>; Michael Roth <Michael.Roth@amd.com>; Brijesh
> Singh <brijesh.singh@amd.com>
> Subject: [RFC PATCH v4 00/27] Add AMD Secure Nested Paging (SEV-SNP)
> support
> 
> BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3275
> 
> SEV-SNP builds upon existing SEV and SEV-ES functionality while adding
> new hardware-based memory protections. SEV-SNP adds strong memory
> integrity
> 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-SNP
> 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
> NAE"
> 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
> the
> unvalidated memory ranges to the Guest OS.
> 
> At this time we only support the pre-validation. OVMF detects all the available
> system RAM in the PEI phase. When SEV-SNP is enabled, the memory is validated
> before it is made available to the EDK2 core.
> 
> This series does not implements the following SEV-SNP features yet:
> 
> * CPUID filtering
> * Lazy validation
> * Interrupt security
> 
> Additional resources
> ---------------------
> SEV-SNP whitepaper
> https://www.amd.com/system/files/TechDocs/SEV-SNP-strengthening-vm-
> isolation-with-integrity-protection-and-more.pdf
> 
> APM 2: https://www.amd.com/system/files/TechDocs/24593.pdf (section 15.36)
> 
> The complete source is available at
> https://github.com/AMDESE/ovmf/tree/sev-snp-rfc-4
> 
> GHCB spec:
> https://developer.amd.com/wp-content/resources/56421.pdf
> 
> SEV-SNP firmware specification:
> https://www.amd.com/system/files/TechDocs/56860.pdf
> 
> Brijesh Singh (26):
>   OvmfPkg/ResetVector: move SEV specific code in a separate file
>   OvmfPkg/ResetVector: add the macro to invoke MSR protocol based
>     VMGEXIT
>   OvmfPkg/ResetVector: add the macro to request guest termination
>   OvmfPkg: reserve SNP secrets page
>   OvmfPkg: reserve CPUID page for SEV-SNP
>   OvmfPkg/ResetVector: introduce SEV-SNP boot block GUID
>   OvmfPkg/ResetVector: pre-validate the data pages used in SEC phase
>   OvmfPkg/ResetVector: invalidate the GHCB page
>   UefiCpuPkg: Define the SEV-SNP specific dynamic PCDs
>   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/BaseMemEncryptSevLib: skip the pre-validated system RAM
>   OvmfPkg/MemEncryptSevLib: add support to validate > 4GB memory in PEI
>     phase
>   OvmfPkg/SecMain: pre-validate the memory used for decompressing Fv
>   OvmfPkg/PlatformPei: validate the system RAM when SNP is active
>   OvmfPkg/PlatformPei: set the SEV-SNP enabled PCD
>   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
>     enabled
>   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
>     table
> 
> Tom Lendacky (1):
>   UefiCpuPkg/MpInitLib: Use SEV-SNP AP Creation NAE event to launch APs
> 
>  OvmfPkg/OvmfPkg.dec                           |  24 +
>  UefiCpuPkg/UefiCpuPkg.dec                     |  11 +
>  OvmfPkg/AmdSev/AmdSevX64.dsc                  |   5 +-
>  OvmfPkg/Bhyve/BhyveX64.dsc                    |   5 +-
>  OvmfPkg/OvmfPkgIa32.dsc                       |   1 +
>  OvmfPkg/OvmfPkgIa32X64.dsc                    |   6 +-
>  OvmfPkg/OvmfPkgX64.dsc                        |   5 +-
>  OvmfPkg/OvmfXen.dsc                           |   5 +-
>  OvmfPkg/OvmfPkgX64.fdf                        |  14 +-
>  OvmfPkg/AmdSevDxe/AmdSevDxe.inf               |   7 +
>  .../DxeMemEncryptSevLib.inf                   |   3 +
>  .../PeiMemEncryptSevLib.inf                   |   7 +
>  .../SecMemEncryptSevLib.inf                   |   3 +
>  OvmfPkg/PlatformPei/PlatformPei.inf           |   8 +
>  OvmfPkg/ResetVector/ResetVector.inf           |   6 +
>  OvmfPkg/Sec/SecMain.inf                       |   3 +
>  UefiCpuPkg/Library/MpInitLib/DxeMpInitLib.inf |   4 +
>  UefiCpuPkg/Library/MpInitLib/PeiMpInitLib.inf |   4 +
>  MdePkg/Include/Register/Amd/Ghcb.h            |   2 +-
>  .../Guid/ConfidentialComputingSecret.h        |  18 +
>  OvmfPkg/Include/Library/MemEncryptSevLib.h    |  26 ++
>  .../X64/SnpPageStateChange.h                  |  31 ++
>  .../BaseMemEncryptSevLib/X64/VirtualMemory.h  |  19 +
>  UefiCpuPkg/Library/MpInitLib/MpLib.h          |  19 +
>  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             | 126 ++++++
>  .../X64/SecSnpSystemRamValidate.c             |  36 ++
>  .../X64/SnpPageStateChangeInternal.c          | 295 +++++++++++++
>  OvmfPkg/PlatformPei/AmdSev.c                  | 192 ++++++++
>  OvmfPkg/PlatformPei/MemDetect.c               |  21 +
>  OvmfPkg/Sec/SecMain.c                         | 111 +++++
>  UefiCpuPkg/Library/MpInitLib/DxeMpLib.c       |  11 +-
>  .../MpInitLib/Ia32/SevSnpRmpAdjustInternal.c  |  31 ++
>  UefiCpuPkg/Library/MpInitLib/MpLib.c          | 275 +++++++++++-
>  .../MpInitLib/X64/SevSnpRmpAdjustInternal.c   |  44 ++
>  OvmfPkg/FvmainCompactScratchEnd.fdf.inc       |   5 +
>  OvmfPkg/ResetVector/Ia16/ResetVectorVtf0.asm  |  27 ++
>  .../Ia32/{PageTables64.asm => AmdSev.asm}     | 415 +++++++++---------
>  OvmfPkg/ResetVector/Ia32/PageTables64.asm     | 404 +----------------
>  OvmfPkg/ResetVector/ResetVector.nasmb         |   7 +
>  UefiCpuPkg/Library/MpInitLib/MpEqu.inc        |   1 +
>  UefiCpuPkg/Library/MpInitLib/X64/MpFuncs.nasm |  51 +++
>  48 files changed, 1978 insertions(+), 630 deletions(-)
>  create mode 100644
> OvmfPkg/Library/BaseMemEncryptSevLib/X64/SnpPageStateChange.h
>  create mode 100644
> OvmfPkg/Library/BaseMemEncryptSevLib/X64/DxeSnpSystemRamValidate.c
>  create mode 100644
> OvmfPkg/Library/BaseMemEncryptSevLib/X64/PeiSnpSystemRamValidate.c
>  create mode 100644
> OvmfPkg/Library/BaseMemEncryptSevLib/X64/SecSnpSystemRamValidate.c
>  create mode 100644
> OvmfPkg/Library/BaseMemEncryptSevLib/X64/SnpPageStateChangeInternal.c
>  create mode 100644
> UefiCpuPkg/Library/MpInitLib/Ia32/SevSnpRmpAdjustInternal.c
>  create mode 100644
> UefiCpuPkg/Library/MpInitLib/X64/SevSnpRmpAdjustInternal.c
>  copy OvmfPkg/ResetVector/Ia32/{PageTables64.asm => AmdSev.asm} (67%)
> 
> --
> 2.17.1