BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3275
During the SEV-SNP guest launch sequence, two special pages need to be
inserted, the secrets and CPUID. The secrets page, contain the VM
platform communication keys. The guest BIOS and/or OS can use this key
to communicate with the SEV firmware to get the attestation report.
The CPUID page, contain the CPUIDs entries filtered through the AMD-SEV
firmware.
OvmfPkg already reserves the memory for the Secrets Page in the MEMFD.
Extend the MEMFD to reserve the memory for the CPUID page.
See SEV-SNP spec for more information on the content layout of the secrets
and CPUID page, and how it can be used by the SEV-SNP guest VM.
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>
Cc: Erdem Aktas <erdemak...@google.com>
Signed-off-by: Brijesh Singh <brijesh.si...@amd.com>
---
OvmfPkg/OvmfPkg.dec | 6 ++++++
OvmfPkg/OvmfPkgX64.fdf | 3 +++
OvmfPkg/PlatformPei/PlatformPei.inf | 2 ++
OvmfPkg/ResetVector/ResetVector.inf | 2 ++
OvmfPkg/PlatformPei/MemDetect.c | 12 ++++++++++++
OvmfPkg/ResetVector/Ia16/ResetVectorVtf0.asm | 18 ++++++++++++++++++
OvmfPkg/ResetVector/ResetVector.nasmb | 2 ++
7 files changed, 45 insertions(+)
diff --git a/OvmfPkg/OvmfPkg.dec b/OvmfPkg/OvmfPkg.dec
index 6ae733f6e39f..fdb5dacdc7fa 100644
--- a/OvmfPkg/OvmfPkg.dec
+++ b/OvmfPkg/OvmfPkg.dec
@@ -321,6 +321,12 @@ [PcdsFixedAtBuild]
gUefiOvmfPkgTokenSpaceGuid.PcdSevLaunchSecretBase|0x0|UINT32|0x42
gUefiOvmfPkgTokenSpaceGuid.PcdSevLaunchSecretSize|0x0|UINT32|0x43
+ ## The base address and size of the SEV-SNP CPUID Area provisioned by the
+ # SEV-SNP firmware. If this is set in the .fdf, the platform
+ # is responsible for protecting the area from DXE phase overwrites.
+ gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSnpCpuidBase|0x0|UINT32|0x47
+ gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSnpCpuidSize|0x0|UINT32|0x48
+
[PcdsDynamic, PcdsDynamicEx]
gUefiOvmfPkgTokenSpaceGuid.PcdEmuVariableEvent|0|UINT64|2
gUefiOvmfPkgTokenSpaceGuid.PcdOvmfFlashVariablesEnable|FALSE|BOOLEAN|0x10
diff --git a/OvmfPkg/OvmfPkgX64.fdf b/OvmfPkg/OvmfPkgX64.fdf
index 9126b8eb5014..1300af666c49 100644
--- a/OvmfPkg/OvmfPkgX64.fdf
+++ b/OvmfPkg/OvmfPkgX64.fdf
@@ -91,6 +91,9 @@ [FD.MEMFD]
0x00D000|0x001000
gUefiOvmfPkgTokenSpaceGuid.PcdSevLaunchSecretBase|gUefiOvmfPkgTokenSpaceGuid.PcdSevLaunchSecretSize
+0x00E000|0x001000
+gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSnpCpuidBase|gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSnpCpuidSize
+
0x010000|0x010000
gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecPeiTempRamBase|gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecPeiTempRamSize
diff --git a/OvmfPkg/PlatformPei/PlatformPei.inf
b/OvmfPkg/PlatformPei/PlatformPei.inf
index 3256ccfe88d8..89c8e9627c86 100644
--- a/OvmfPkg/PlatformPei/PlatformPei.inf
+++ b/OvmfPkg/PlatformPei/PlatformPei.inf
@@ -120,6 +120,8 @@ [FixedPcd]
gEmbeddedTokenSpaceGuid.PcdMemoryTypeEfiReservedMemoryType
gEmbeddedTokenSpaceGuid.PcdMemoryTypeEfiRuntimeServicesCode
gEmbeddedTokenSpaceGuid.PcdMemoryTypeEfiRuntimeServicesData
+ gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSnpCpuidBase
+ gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSnpCpuidSize
gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecGhcbBackupBase
gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecGhcbBackupSize
gUefiCpuPkgTokenSpaceGuid.PcdSevEsWorkAreaBase
diff --git a/OvmfPkg/ResetVector/ResetVector.inf
b/OvmfPkg/ResetVector/ResetVector.inf
index dc38f68919cd..8e52265602c3 100644
--- a/OvmfPkg/ResetVector/ResetVector.inf
+++ b/OvmfPkg/ResetVector/ResetVector.inf
@@ -45,5 +45,7 @@ [Pcd]
gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecPeiTempRamSize
[FixedPcd]
+ gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSnpCpuidBase
+ gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSnpCpuidSize
gUefiOvmfPkgTokenSpaceGuid.PcdSevLaunchSecretBase
gUefiOvmfPkgTokenSpaceGuid.PcdSevLaunchSecretSize
diff --git a/OvmfPkg/PlatformPei/MemDetect.c b/OvmfPkg/PlatformPei/MemDetect.c
index c08aa2e45a53..483e92af8219 100644
--- a/OvmfPkg/PlatformPei/MemDetect.c
+++ b/OvmfPkg/PlatformPei/MemDetect.c
@@ -894,6 +894,18 @@ InitializeRamRegions (
EfiACPIMemoryNVS
);
}
+
+ if (MemEncryptSevSnpIsEnabled ()) {
+ //
+ // If SEV-SNP is enabled, reserve the CPUID page. The memory range should
+ // not be treated as a RAM by the guest OS, so, mark it as reserved.
+ //
+ BuildMemoryAllocationHob (
+ (EFI_PHYSICAL_ADDRESS)(UINTN) PcdGet32 (PcdOvmfSnpCpuidBase),
+ (UINT64)(UINTN) PcdGet32 (PcdOvmfSnpCpuidSize),
+ EfiReservedMemoryType
+ );
+ }
#endif
}
diff --git a/OvmfPkg/ResetVector/Ia16/ResetVectorVtf0.asm
b/OvmfPkg/ResetVector/Ia16/ResetVectorVtf0.asm
index 9c0b5853a46f..05c7e32f46a0 100644
--- a/OvmfPkg/ResetVector/Ia16/ResetVectorVtf0.asm
+++ b/OvmfPkg/ResetVector/Ia16/ResetVectorVtf0.asm
@@ -47,6 +47,24 @@ TIMES (15 - ((guidedStructureEnd - guidedStructureStart +
15) % 16)) DB 0
;
guidedStructureStart:
+;
+; SEV-SNP boot support
+;
+; sevSnpBlock:
+; For the initial boot of SEV-SNP guest, a CPUID page must be reserved by
+; the BIOS at a RAM area defined by SEV_SNP_CPUID_BASE. A hypervisor will
+; locate this information using the SEV-SNP boot block GUID.
+;
+; GUID (SEV-SNP boot block): bd39c0c2-2f8e-4243-83e8-1b74cebcb7d9
+;
+sevSnpBootBlockStart:
+ DD SNP_CPUID_BASE
+ DD SNP_CPUID_SIZE
+ DW sevSnpBootBlockEnd - sevSnpBootBlockStart
+ DB 0xC2, 0xC0, 0x39, 0xBD, 0x8e, 0x2F, 0x43, 0x42
+ DB 0x83, 0xE8, 0x1B, 0x74, 0xCE, 0xBC, 0xB7, 0xD9
+sevSnpBootBlockEnd:
+
;
; SEV Secret block
;
diff --git a/OvmfPkg/ResetVector/ResetVector.nasmb
b/OvmfPkg/ResetVector/ResetVector.nasmb
index 5beba3ecb290..36739096e7e1 100644
--- a/OvmfPkg/ResetVector/ResetVector.nasmb
+++ b/OvmfPkg/ResetVector/ResetVector.nasmb
@@ -90,5 +90,7 @@
%define SEV_ES_AP_RESET_IP FixedPcdGet32 (PcdSevEsWorkAreaBase)
%define SEV_LAUNCH_SECRET_BASE FixedPcdGet32 (PcdSevLaunchSecretBase)
%define SEV_LAUNCH_SECRET_SIZE FixedPcdGet32 (PcdSevLaunchSecretSize)
+ %define SNP_CPUID_BASE FixedPcdGet32 (PcdOvmfSnpCpuidBase)
+ %define SNP_CPUID_SIZE FixedPcdGet32 (PcdOvmfSnpCpuidSize)
%include "Ia16/ResetVectorVtf0.asm"
--
2.17.1
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