Hi Brijesh, On 03/24/21 16:31, Brijesh Singh wrote: > 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.
Can you describe this in a bit more detail, before I look at the individual patches? Specifically, what existing logic in the PEI phase was taken, and extended, and how? If there is a particular patch whose commit message is closely related to my question, can you point it out? Patch#15 perhaps? (Doesn't seem like a big patch; for some reason I'd expect something more complex, but perhaps that's only because it builds upon the many earlier patches.) Thanks, Laszlo > > This series does not implements the following SEV-SNP features yet: > > * CPUID filtering > * AP bring up using the new SEV-SNP NAE > * Lazy validation > * Interrupt security > > The series is based on commit: > e542e05d4f UefiCpuPkg/SmmCpuFeaturesLib: Abstract > PcdCpuMaxLogicalProcessorNumber > > 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-1 > > GHCB spec v2: > The draft specification is posted on AMD-SEV-SNP mailing list: > https://lists.suse.com/mailman/private/amd-sev-snp/ > > Copy of the spec is also available at > > https://github.com/AMDESE/AMDSEV/blob/sev-snp-devel/docs/56421-Guest_Hypervisor_Communication_Block_Standardization.pdf > > GHCB spec v1: > SEV-SNP firmware specification: > https://developer.amd.com/sev/ > > Cc: James Bottomley <j...@linux.ibm.com> > Cc: Min Xu <min.m...@intel.com> > Cc: Jiewen Yao <jiewen....@intel.com> > Cc: Tom Lendacky <thomas.lenda...@amd.com> > Cc: Jordan Justen <jordan.l.jus...@intel.com> > Cc: Ard Biesheuvel <ardb+tianoc...@kernel.org> > Cc: Laszlo Ersek <ler...@redhat.com> > > Brijesh Singh (19): > OvmfPkg: Reserve the Secrets and Cpuid page for the SEV-SNP guest > OvmfPkg: validate the data pages used in the SEC phase > MdePkg: Expand the SEV MSR to include the SNP definition > OvmfPkg/MemEncryptSevLib: add MemEncryptSevSnpEnabled() > MdePkg: Define the GHCB GPA structure > UefiCpuPkg/MpLib: add support to register GHCB GPA when SEV-SNP is > enabled > OvmfPkg: Add a library to support registering GHCB GPA > OvmfPkg: register GHCB gpa for the SEV-SNP guest > MdePkg: Add AsmPvalidate() support > OvmfPkg: Define the Page State Change VMGEXIT structures > OvmfPkg/ResetVector: Invalidate the GHCB page > OvmfPkg/MemEncryptSevLib: Add support to validate system RAM > OvmfPkg/SecMain: Validate the data/code pages used for the PEI phase > OvmfPkg/MemEncryptSevLib: Add support to validate RAM in PEI phase > OvmfPkg/PlatformPei: Validate the system RAM when SNP is active > OvmfPkg/MemEncryptSevLib: Add support to validate > 4GB memory in PEI > phase > OvmfPkg/VmgExitLib: Allow PMBASE register access in Dxe phase > OvmfPkg/MemEncryptSevLib: Validate the memory during set or clear enc > attribute > OvmfPkg/MemEncryptSevLib: Skip page state change for non RAM region > > MdePkg/Include/Library/BaseLib.h | 37 +++ > MdePkg/Include/Register/Amd/Fam17Msr.h | 31 ++- > MdePkg/Include/Register/Amd/Ghcb.h | 39 ++- > MdePkg/Library/BaseLib/BaseLib.inf | 1 + > MdePkg/Library/BaseLib/X64/Pvalidate.nasm | 43 +++ > OvmfPkg/Include/Library/GhcbRegisterLib.h | 27 ++ > OvmfPkg/Include/Library/MemEncryptSevLib.h | 30 +++ > .../DxeMemEncryptSevLib.inf | 7 + > .../DxeMemEncryptSevLibInternal.c | 27 ++ > .../Ia32/SnpPageStateChange.c | 17 ++ > .../PeiMemEncryptSevLib.inf | 9 + > .../PeiMemEncryptSevLibInternal.c | 47 ++++ > .../SecMemEncryptSevLib.inf | 4 + > .../SecMemEncryptSevLibInternal.c | 39 +++ > .../BaseMemEncryptSevLib/SnpPageStateChange.h | 37 +++ > .../X64/PeiDxeSnpSetPageState.c | 63 +++++ > .../X64/PeiDxeVirtualMemory.c | 151 ++++++++++- > .../X64/PeiSnpSystemRamValidate.c | 129 +++++++++ > .../X64/SecSnpSystemRamValidate.c | 23 ++ > .../X64/SnpPageStateChangeInternal.c | 254 ++++++++++++++++++ > .../X64/SnpPageStateTrack.c | 119 ++++++++ > .../X64/SnpPageStateTrack.h | 36 +++ > .../X64/SnpSetPageState.h | 27 ++ > .../BaseMemEncryptSevLib/X64/VirtualMemory.h | 19 ++ > .../Library/GhcbRegisterLib/GhcbRegisterLib.c | 97 +++++++ > .../GhcbRegisterLib/GhcbRegisterLib.inf | 33 +++ > OvmfPkg/Library/VmgExitLib/SecVmgExitLib.inf | 4 + > OvmfPkg/Library/VmgExitLib/VmgExitLib.inf | 7 + > OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c | 45 ++++ > OvmfPkg/OvmfPkg.dec | 12 + > OvmfPkg/OvmfPkgX64.dsc | 1 + > OvmfPkg/OvmfPkgX64.fdf | 33 ++- > OvmfPkg/PlatformPei/AmdSev.c | 52 ++++ > OvmfPkg/PlatformPei/PlatformPei.inf | 2 + > OvmfPkg/ResetVector/Ia16/ResetVectorVtf0.asm | 24 ++ > OvmfPkg/ResetVector/Ia32/PageTables64.asm | 106 ++++++++ > OvmfPkg/ResetVector/ResetVector.inf | 5 + > OvmfPkg/ResetVector/ResetVector.nasmb | 4 + > OvmfPkg/Sec/SecMain.c | 102 +++++++ > OvmfPkg/Sec/SecMain.inf | 2 + > UefiCpuPkg/Library/MpInitLib/DxeMpInitLib.inf | 1 + > UefiCpuPkg/Library/MpInitLib/MpEqu.inc | 1 + > UefiCpuPkg/Library/MpInitLib/MpLib.c | 2 + > UefiCpuPkg/Library/MpInitLib/MpLib.h | 2 + > UefiCpuPkg/Library/MpInitLib/PeiMpInitLib.inf | 1 + > UefiCpuPkg/Library/MpInitLib/X64/MpFuncs.nasm | 51 ++++ > UefiCpuPkg/UefiCpuPkg.dec | 6 + > 47 files changed, 1790 insertions(+), 19 deletions(-) > create mode 100644 MdePkg/Library/BaseLib/X64/Pvalidate.nasm > create mode 100644 OvmfPkg/Include/Library/GhcbRegisterLib.h > create mode 100644 > OvmfPkg/Library/BaseMemEncryptSevLib/Ia32/SnpPageStateChange.c > create mode 100644 OvmfPkg/Library/BaseMemEncryptSevLib/SnpPageStateChange.h > create mode 100644 > OvmfPkg/Library/BaseMemEncryptSevLib/X64/PeiDxeSnpSetPageState.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/BaseMemEncryptSevLib/X64/SnpPageStateTrack.c > create mode 100644 > OvmfPkg/Library/BaseMemEncryptSevLib/X64/SnpPageStateTrack.h > create mode 100644 OvmfPkg/Library/BaseMemEncryptSevLib/X64/SnpSetPageState.h > create mode 100644 OvmfPkg/Library/GhcbRegisterLib/GhcbRegisterLib.c > create mode 100644 OvmfPkg/Library/GhcbRegisterLib/GhcbRegisterLib.inf > -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. 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