[RFC PATCH v5 00/28] Add AMD Secure Nested Paging (SEV-SNP) support


Brijesh Singh
 

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-5

GHCB spec:
https://developer.amd.com/wp-content/resources/56421.pdf

SEV-SNP firmware specification:
https://www.amd.com/system/files/TechDocs/56860.pdf

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 keep
the code readable.
* Drop extending the EsWorkArea to contain SNP specific state.
* Drop the GhcbGpa library and call the VmgExit directly to register GHCB GPA.
* 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 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 (27):
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
OvmfPkg/ResetVector: check the vmpl level
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} | 502 +++++++++++-------
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, 2065 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} (57%)

--
2.17.1

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