BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3275
Platform features and capabilities are traditionally discovered via the CPUID instruction. Hypervisors typically trap and emulate the CPUID instruction for a variety of reasons. There are some cases where incorrect CPUID information can potentially lead to a security issue. The SEV-SNP firmware provides a feature to filter the CPUID results through the PSP. The filtered CPUID values are saved on a special page for the guest to consume. Reserve a page in MEMFD that will contain the results of filtered CPUID values. Cc: Michael Roth <michael.r...@amd.com> 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: Erdem Aktas <erdemak...@google.com> Cc: Gerd Hoffmann <kra...@redhat.com> Acked-by: Jiewen Yao <jiewen....@intel.com> Acked-by: Gerd Hoffmann <kra...@redhat.com> Signed-off-by: Brijesh Singh <brijesh.si...@amd.com> --- OvmfPkg/OvmfPkg.dec | 7 +++++++ OvmfPkg/OvmfPkgX64.fdf | 3 +++ OvmfPkg/ResetVector/ResetVector.inf | 2 ++ OvmfPkg/ResetVector/ResetVector.nasmb | 2 ++ OvmfPkg/ResetVector/X64/OvmfSevMetadata.asm | 16 ++++++++++++++++ 5 files changed, 30 insertions(+) diff --git a/OvmfPkg/OvmfPkg.dec b/OvmfPkg/OvmfPkg.dec index deb285fd62c5..bc14cf2ed403 100644 --- a/OvmfPkg/OvmfPkg.dec +++ b/OvmfPkg/OvmfPkg.dec @@ -357,6 +357,13 @@ [PcdsFixedAtBuild] gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSnpSecretsBase|0|UINT32|0x58 gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSnpSecretsSize|0|UINT32|0x59 + ## The base address and size of a CPUID Area that contains the hypervisor + # provided CPUID results. In the case of SEV-SNP, the CPUID results are + # filtered by the SEV-SNP firmware. If this is set in the .fdf, the + # platform is responsible to reserve this area from DXE phase overwrites. + gUefiOvmfPkgTokenSpaceGuid.PcdOvmfCpuidBase|0|UINT32|0x60 + gUefiOvmfPkgTokenSpaceGuid.PcdOvmfCpuidSize|0|UINT32|0x61 + [PcdsDynamic, PcdsDynamicEx] gUefiOvmfPkgTokenSpaceGuid.PcdEmuVariableEvent|0|UINT64|2 gUefiOvmfPkgTokenSpaceGuid.PcdOvmfFlashVariablesEnable|FALSE|BOOLEAN|0x10 diff --git a/OvmfPkg/OvmfPkgX64.fdf b/OvmfPkg/OvmfPkgX64.fdf index 1313c7f016bf..e94b433e7b28 100644 --- a/OvmfPkg/OvmfPkgX64.fdf +++ b/OvmfPkg/OvmfPkgX64.fdf @@ -91,6 +91,9 @@ [FD.MEMFD] 0x00D000|0x001000 gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSnpSecretsBase|gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSnpSecretsSize +0x00E000|0x001000 +gUefiOvmfPkgTokenSpaceGuid.PcdOvmfCpuidBase|gUefiOvmfPkgTokenSpaceGuid.PcdOvmfCpuidSize + 0x010000|0x010000 gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecPeiTempRamBase|gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecPeiTempRamSize diff --git a/OvmfPkg/ResetVector/ResetVector.inf b/OvmfPkg/ResetVector/ResetVector.inf index fcbc25d0ce3d..1c5d84184ed7 100644 --- a/OvmfPkg/ResetVector/ResetVector.inf +++ b/OvmfPkg/ResetVector/ResetVector.inf @@ -55,6 +55,8 @@ [Pcd] gUefiOvmfPkgTokenSpaceGuid.PcdBfvRawDataSize [FixedPcd] + gUefiOvmfPkgTokenSpaceGuid.PcdOvmfCpuidBase + gUefiOvmfPkgTokenSpaceGuid.PcdOvmfCpuidSize gUefiOvmfPkgTokenSpaceGuid.PcdSevLaunchSecretBase gUefiOvmfPkgTokenSpaceGuid.PcdSevLaunchSecretSize gUefiOvmfPkgTokenSpaceGuid.PcdQemuHashTableBase diff --git a/OvmfPkg/ResetVector/ResetVector.nasmb b/OvmfPkg/ResetVector/ResetVector.nasmb index 4e685ef23684..fbaeab5f5168 100644 --- a/OvmfPkg/ResetVector/ResetVector.nasmb +++ b/OvmfPkg/ResetVector/ResetVector.nasmb @@ -105,6 +105,8 @@ %define SEV_ES_VC_TOP_OF_STACK (FixedPcdGet32 (PcdOvmfSecPeiTempRamBase) + FixedPcdGet32 (PcdOvmfSecPeiTempRamSize)) %define SEV_SNP_SECRETS_BASE (FixedPcdGet32 (PcdOvmfSnpSecretsBase)) %define SEV_SNP_SECRETS_SIZE (FixedPcdGet32 (PcdOvmfSnpSecretsSize)) + %define CPUID_BASE (FixedPcdGet32 (PcdOvmfCpuidBase)) + %define CPUID_SIZE (FixedPcdGet32 (PcdOvmfCpuidSize)) %include "X64/IntelTdxMetadata.asm" %include "Ia32/Flat32ToFlat64.asm" diff --git a/OvmfPkg/ResetVector/X64/OvmfSevMetadata.asm b/OvmfPkg/ResetVector/X64/OvmfSevMetadata.asm index 2bc7790bd808..0cc12ad3473f 100644 --- a/OvmfPkg/ResetVector/X64/OvmfSevMetadata.asm +++ b/OvmfPkg/ResetVector/X64/OvmfSevMetadata.asm @@ -17,6 +17,16 @@ BITS 64 ; AMD SEV-SNP specific sections %define OVMF_SECTION_TYPE_SNP_SECRETS 0x2 +; +; The section contains the hypervisor pre-populated CPUID values. +; In the case of SEV-SNP, the CPUID values are filtered and measured by +; the SEV-SNP firmware. +; The CPUID format is documented in SEV-SNP firmware spec 0.9 section 7.1 +; (CPUID function structure). +; +%define OVMF_SECTION_TYPE_CPUID 0x3 + + ALIGN 16 TIMES (15 - ((OvmfSevGuidedStructureEnd - OvmfSevGuidedStructureStart + 15) % 16)) DB 0 @@ -39,5 +49,11 @@ SevSnpSecrets: DD SEV_SNP_SECRETS_SIZE DD OVMF_SECTION_TYPE_SNP_SECRETS +; CPUID values +CpuidSec: + DD CPUID_BASE + DD CPUID_SIZE + DD OVMF_SECTION_TYPE_CPUID + OvmfSevGuidedStructureEnd: ALIGN 16 -- 2.25.1 -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. 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