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OvmfPkg: reserve CPUID page

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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.roth@amd.com>
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: Erdem Aktas <erdemaktas@google.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Acked-by: Jiewen Yao <Jiewen.yao@intel.com>
Acked-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
This commit is contained in:
Brijesh Singh via groups.io
2021-12-09 11:27:34 +08:00
committed by mergify[bot]
parent 707c71a01b
commit cca9cd3dd6
5 changed files with 30 additions and 0 deletions
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7
OvmfPkg/OvmfPkg.dec
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@@ -357,6 +357,13 @@
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