Re: [edk2-devel] [RESEND PATCH RFC v3 00/22] Add AMD Secure Nested Paging (SEV-SNP) support

["Laszlo Ersek" <lersek@redhat.com>]

On 05/27/21 01:10, Brijesh Singh wrote:
> (I missed adding devel@edk2.groups.io, resending the series)
> 
> 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
> 
> The series builds on SNP pre-patch posted here: https://tinyurl.com/pu6admks
> 
> 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-2
> 
> GHCB spec:
> https://developer.amd.com/wp-content/resources/56421.pdf
> 
> SEV-SNP firmware specification:
> https://developer.amd.com/sev/
> 	         
> Cc: James Bottomley <jejb@linux.ibm.com>
> Cc: Min Xu <min.m.xu@intel.com>
> Cc: Jiewen Yao <jiewen.yao@intel.com>
> Cc: Tom Lendacky <thomas.lendacky@amd.com>
> Cc: Jordan Justen <jordan.l.justen@intel.com>
> Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
> Cc: Laszlo Ersek <lersek@redhat.com>
> Cc: Erdem Aktas <erdemaktas@google.com>
> 
> Changes since v2:
>  * Add support for the AP creation.
>  * Use the module-scoping override to make AmdSevDxe use the IO port for PCI reads.
>  * 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 supported.
>  * Introduce MemEncryptSevClearMmioPageEncMask() to clear the C-bit from MMIO ranges.
>  * Pull the SevSecretDxe and SevSecretPei into OVMF package build.
>  * Extend the SevSecretDxe to expose confidential computing blob location through
>    EFI configuration table.
> 
> Brijesh Singh (21):
>   UefiCpuPkg: Define the SEV-SNP specific dynamic PCDs
>   OvmfPkg/MemEncryptSevLib: add MemEncryptSevSnpEnabled()
>   OvmfPkg/MemEncryptSevLib: extend the workarea to include SNP enabled
>     field
>   OvmfPkg/MemEncryptSevLib: extend Es Workarea to include hv features
>   OvmfPkg: reserve Secrets page in MEMFD
>   OvmfPkg: reserve CPUID page for the SEV-SNP guest
>   OvmfPkg/ResetVector: validate the data pages used in SEC phase
>   OvmfPkg/ResetVector: invalidate the GHCB page
>   OvmfPkg: add library to support registering GHCB GPA
>   OvmfPkg/PlatformPei: register GHCB gpa for the SEV-SNP guest
>   UefiCpuPkg/MpLib: add support to register GHCB GPA when SEV-SNP is
>     enabled
>   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/MemEncryptSevLib: Change the page state in the RMP table
>   OvmfPkg/MemEncryptSevLib: skip page state change for Mmio address
>   OvmfPkg/AmdSev: expose the SNP reserved pages through configuration
>     table
>   MdePkg/GHCB: increase the GHCB protocol max version
> 
> Tom Lendacky (1):
>   UefiCpuPkg/MpInitLib: Use SEV-SNP AP Creation NAE event to launch APs
> 
>  OvmfPkg/OvmfPkg.dec                           |  21 ++
>  UefiCpuPkg/UefiCpuPkg.dec                     |  11 +
>  OvmfPkg/AmdSev/AmdSevX64.dsc                  |   5 +-
>  OvmfPkg/Bhyve/BhyveX64.dsc                    |   5 +-
>  OvmfPkg/OvmfPkgIa32.dsc                       |   2 +
>  OvmfPkg/OvmfPkgIa32X64.dsc                    |   7 +-
>  OvmfPkg/OvmfPkgX64.dsc                        |   8 +-
>  OvmfPkg/OvmfXen.dsc                           |   5 +-
>  OvmfPkg/OvmfPkgX64.fdf                        |  17 +-
>  OvmfPkg/AmdSev/SecretDxe/SecretDxe.inf        |   4 +
>  OvmfPkg/AmdSev/SecretPei/SecretPei.inf        |   1 +
>  .../DxeMemEncryptSevLib.inf                   |   3 +
>  .../PeiMemEncryptSevLib.inf                   |   7 +
>  .../SecMemEncryptSevLib.inf                   |   3 +
>  .../GhcbRegisterLib/GhcbRegisterLib.inf       |  33 +++
>  OvmfPkg/PlatformPei/PlatformPei.inf           |   5 +
>  OvmfPkg/ResetVector/ResetVector.inf           |   4 +
>  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/GhcbRegisterLib.h     |  27 ++
>  OvmfPkg/Include/Library/MemEncryptSevLib.h    |  31 +-
>  .../X64/SnpPageStateChange.h                  |  31 ++
>  .../BaseMemEncryptSevLib/X64/VirtualMemory.h  |  19 ++
>  UefiCpuPkg/Library/MpInitLib/MpLib.h          |  19 ++
>  OvmfPkg/AmdSev/SecretDxe/SecretDxe.c          |  22 ++
>  OvmfPkg/AmdSev/SecretPei/SecretPei.c          |  15 +-
>  .../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          | 230 +++++++++++++++
>  .../Library/GhcbRegisterLib/GhcbRegisterLib.c |  97 +++++++
>  OvmfPkg/PlatformPei/AmdSev.c                  |  81 ++++++
>  OvmfPkg/PlatformPei/MemDetect.c               |  12 +
>  OvmfPkg/Sec/SecMain.c                         | 106 +++++++
>  UefiCpuPkg/Library/MpInitLib/DxeMpLib.c       |  11 +-
>  .../MpInitLib/Ia32/SevSnpRmpAdjustInternal.c  |  31 ++
>  UefiCpuPkg/Library/MpInitLib/MpLib.c          | 274 ++++++++++++++++--
>  .../MpInitLib/X64/SevSnpRmpAdjustInternal.c   |  44 +++
>  OvmfPkg/FvmainCompactScratchEnd.fdf.inc       |   5 +
>  OvmfPkg/ResetVector/Ia16/ResetVectorVtf0.asm  |  23 ++
>  OvmfPkg/ResetVector/Ia32/PageTables64.asm     | 227 +++++++++++++++
>  OvmfPkg/ResetVector/ResetVector.nasmb         |   6 +
>  UefiCpuPkg/Library/MpInitLib/MpEqu.inc        |   1 +
>  UefiCpuPkg/Library/MpInitLib/X64/MpFuncs.nasm |  51 ++++
>  52 files changed, 1956 insertions(+), 38 deletions(-)
>  create mode 100644 OvmfPkg/Library/GhcbRegisterLib/GhcbRegisterLib.inf
>  create mode 100644 OvmfPkg/Include/Library/GhcbRegisterLib.h
>  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 OvmfPkg/Library/GhcbRegisterLib/GhcbRegisterLib.c
>  create mode 100644 UefiCpuPkg/Library/MpInitLib/Ia32/SevSnpRmpAdjustInternal.c
>  create mode 100644 UefiCpuPkg/Library/MpInitLib/X64/SevSnpRmpAdjustInternal.c
> 

I'm confirming that this series is in my review queue.

However, I may need unusually long time to get to it. Thanks for your
patience.

Thanks
Laszlo