[PATCH v11 05/32] OvmfPkg: reserve SNP secrets page


Brijesh Singh
 

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

During the SNP guest launch sequence, a special secrets page needs to be
inserted by the VMM. The PSP will populate the page; it will contain the
VM Platform Communication Key (VMPCKs) used by the guest to send and
receive secure messages to the PSP.

The purpose of the secrets page in the SEV-SNP is different from the one
used in SEV guests. In SEV, the secrets page contains the guest owner's
private data after the remote attestation.

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>
---
OvmfPkg/OvmfPkg.dec | 6 ++++++
OvmfPkg/OvmfPkgX64.fdf | 3 +++
OvmfPkg/ResetVector/ResetVector.inf | 2 ++
OvmfPkg/ResetVector/ResetVector.nasmb | 2 ++
OvmfPkg/ResetVector/X64/OvmfSevMetadata.asm | 9 +++++++++
5 files changed, 22 insertions(+)

diff --git a/OvmfPkg/OvmfPkg.dec b/OvmfPkg/OvmfPkg.dec
index 1be8d5dccbc7..3e4e80a1e5a0 100644
--- a/OvmfPkg/OvmfPkg.dec
+++ b/OvmfPkg/OvmfPkg.dec
@@ -340,6 +340,12 @@ [PcdsFixedAtBuild]
# header definition.
gUefiOvmfPkgTokenSpaceGuid.PcdOvmfConfidentialComputingWorkAreaHeader|4|UINT32|0x51

+ ## The base address and size of the SEV-SNP Secrets Area that contains
+ # the VM platform communication key used to send and recieve the
+ # messages to the PSP. If this is set in the .fdf, the platform
+ # is responsible to reserve this area from DXE phase overwrites.
+ gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSnpSecretsBase|0|UINT32|0x52
+ gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSnpSecretsSize|0|UINT32|0x53

[PcdsDynamic, PcdsDynamicEx]
gUefiOvmfPkgTokenSpaceGuid.PcdEmuVariableEvent|0|UINT64|2
diff --git a/OvmfPkg/OvmfPkgX64.fdf b/OvmfPkg/OvmfPkgX64.fdf
index b6cc3cabdd69..1313c7f016bf 100644
--- a/OvmfPkg/OvmfPkgX64.fdf
+++ b/OvmfPkg/OvmfPkgX64.fdf
@@ -88,6 +88,9 @@ [FD.MEMFD]
0x00C000|0x001000
gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecGhcbBackupBase|gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecGhcbBackupSize

+0x00D000|0x001000
+gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSnpSecretsBase|gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSnpSecretsSize
+
0x010000|0x010000
gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecPeiTempRamBase|gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecPeiTempRamSize

diff --git a/OvmfPkg/ResetVector/ResetVector.inf b/OvmfPkg/ResetVector/ResetVector.inf
index a2520dde5508..09454d0797e6 100644
--- a/OvmfPkg/ResetVector/ResetVector.inf
+++ b/OvmfPkg/ResetVector/ResetVector.inf
@@ -50,3 +50,5 @@ [FixedPcd]
gUefiOvmfPkgTokenSpaceGuid.PcdSevLaunchSecretSize
gUefiOvmfPkgTokenSpaceGuid.PcdQemuHashTableBase
gUefiOvmfPkgTokenSpaceGuid.PcdQemuHashTableSize
+ gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSnpSecretsBase
+ gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSnpSecretsSize
diff --git a/OvmfPkg/ResetVector/ResetVector.nasmb b/OvmfPkg/ResetVector/ResetVector.nasmb
index 6a3b1b73cf53..e6a868730897 100644
--- a/OvmfPkg/ResetVector/ResetVector.nasmb
+++ b/OvmfPkg/ResetVector/ResetVector.nasmb
@@ -78,6 +78,8 @@
%define SEV_ES_WORK_AREA_RDRAND (FixedPcdGet32 (PcdSevEsWorkAreaBase) + 8)
%define SEV_ES_WORK_AREA_ENC_MASK (FixedPcdGet32 (PcdSevEsWorkAreaBase) + 16)
%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))
%include "Ia32/Flat32ToFlat64.asm"
%include "Ia32/AmdSev.asm"
%include "Ia32/PageTables64.asm"
diff --git a/OvmfPkg/ResetVector/X64/OvmfSevMetadata.asm b/OvmfPkg/ResetVector/X64/OvmfSevMetadata.asm
index c42ad779be49..eba861129333 100644
--- a/OvmfPkg/ResetVector/X64/OvmfSevMetadata.asm
+++ b/OvmfPkg/ResetVector/X64/OvmfSevMetadata.asm
@@ -14,6 +14,9 @@ BITS 64
; The section must be accepted or validated by the VMM before the boot
%define OVMF_SECTION_TYPE_SNP_SEC_MEM 0x1

+; AMD SEV-SNP specific sections
+%define OVMF_SECTION_TYPE_SNP_SECRETS 0x2
+
ALIGN 16

TIMES (15 - ((OvmfSevGuidedStructureEnd - OvmfSevGuidedStructureStart + 15) % 16)) DB 0
@@ -30,5 +33,11 @@ _Descriptor:
DD OVMF_SEV_METADATA_VERSION ; Version
DD (OvmfSevGuidedStructureEnd - _Descriptor - 16) / 12 ; Number of sections

+; SEV-SNP Secrets page
+SevSnpSecrets:
+ DD SEV_SNP_SECRETS_BASE
+ DD SEV_SNP_SECRETS_SIZE
+ DD OVMF_SECTION_TYPE_SNP_SECRETS
+
OvmfSevGuidedStructureEnd:
ALIGN 16
--
2.25.1