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OvmfPkg/ResetVector: introduce SEV metadata descriptor for VMM use 

BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3275

The OvmfPkgX86 build reserves memory regions in MEMFD. The memory regions
get accessed in the SEC phase. AMD SEV-SNP require that the guest's
private memory be accepted or validated before access.

Introduce a Guided metadata structure that describes the reserved memory
regions. The VMM can locate the metadata structure by iterating through
the reset vector guid and process the areas based on the platform
specific requirements.

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: 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 11:27:32 +08:00 committed by mergify[bot]
parent 2fe8edfe55
commit 3053183d41
3 changed files with 49 additions and 0 deletions
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14
OvmfPkg/ResetVector/Ia16/ResetVectorVtf0.asm
View File

@ -64,6 +64,20 @@ tdxMetadataOffsetStart:
DB 0x86, 0x5e, 0x46, 0x85, 0xa7, 0xbf, 0x8e, 0xc2
tdxMetadataOffsetEnd:
;
; SEV metadata descriptor
;
; Provide the start offset of the metadata blob within the OVMF binary.
; GUID : dc886566-984a-4798-A75e-5585a7bf67cc
;
OvmfSevMetadataOffsetStart:
DD (fourGigabytes - OvmfSevMetadataGuid)
DW OvmfSevMetadataOffsetEnd - OvmfSevMetadataOffsetStart
DB 0x66, 0x65, 0x88, 0xdc, 0x4a, 0x98, 0x98, 0x47
DB 0xA7, 0x5e, 0x55, 0x85, 0xa7, 0xbf, 0x67, 0xcc
OvmfSevMetadataOffsetEnd:
%endif
; SEV Hash Table Block

1
OvmfPkg/ResetVector/ResetVector.nasmb
View File

@ -109,6 +109,7 @@
%include "Ia32/AmdSev.asm"
%include "Ia32/PageTables64.asm"
%include "Ia32/IntelTdx.asm"
%include "X64/OvmfSevMetadata.asm"
%endif
%include "Ia16/Real16ToFlat32.asm"

34
OvmfPkg/ResetVector/X64/OvmfSevMetadata.asm Normal file
View File

@ -0,0 +1,34 @@
;-----------------------------------------------------------------------------
; @file
; OVMF metadata for the AMD SEV confidential computing guests
;
; Copyright (c) 2021, AMD Inc. All rights reserved.<BR>
;
; SPDX-License-Identifier: BSD-2-Clause-Patent
;-----------------------------------------------------------------------------
BITS 64
%define OVMF_SEV_METADATA_VERSION 1
; The section must be accepted or validated by the VMM before the boot
%define OVMF_SECTION_TYPE_SNP_SEC_MEM 0x1
ALIGN 16
TIMES (15 - ((OvmfSevGuidedStructureEnd - OvmfSevGuidedStructureStart + 15) % 16)) DB 0
OvmfSevGuidedStructureStart:
;
; OvmfSev metadata descriptor
;
OvmfSevMetadataGuid:
_DescriptorSev:
DB 'A','S','E','V' ; Signature
DD OvmfSevGuidedStructureEnd - _DescriptorSev ; Length
DD OVMF_SEV_METADATA_VERSION ; Version
DD (OvmfSevGuidedStructureEnd - _DescriptorSev - 16) / 12 ; Number of sections
OvmfSevGuidedStructureEnd:
ALIGN 16