[RFC PATCH v5 06/28] OvmfPkg/ResetVector: introduce SEV-SNP boot block GUID

["Brijesh Singh" <brijesh.singh@amd.com>]

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

Introduce a new SEV-SNP boot-specific GUID block. The block is used to
communicate the secrets and cpuid memory area reserved by the guest BIOS.
When SEV-SNP is enabled, the hypervisor will locate the SEV-SNP boot
block to get the location of the Secrets and CPUID page and call the
PSP firmware command to populate those memory areas.

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: Laszlo Ersek <lersek@redhat.com>
Cc: Erdem Aktas <erdemaktas@google.com>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
---
 OvmfPkg/ResetVector/ResetVector.inf          |  4 ++++
 OvmfPkg/ResetVector/Ia16/ResetVectorVtf0.asm | 22 ++++++++++++++++++++
 OvmfPkg/ResetVector/ResetVector.nasmb        |  4 ++++
 3 files changed, 30 insertions(+)

diff --git a/OvmfPkg/ResetVector/ResetVector.inf b/OvmfPkg/ResetVector/ResetVector.inf
index dc38f68919cd..9a95d8687345 100644
--- a/OvmfPkg/ResetVector/ResetVector.inf
+++ b/OvmfPkg/ResetVector/ResetVector.inf
@@ -47,3 +47,7 @@ [Pcd]
 [FixedPcd]
   gUefiOvmfPkgTokenSpaceGuid.PcdSevLaunchSecretBase
   gUefiOvmfPkgTokenSpaceGuid.PcdSevLaunchSecretSize
+  gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSnpSecretsBase
+  gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSnpSecretsSize
+  gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSnpCpuidBase
+  gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSnpCpuidSize
diff --git a/OvmfPkg/ResetVector/Ia16/ResetVectorVtf0.asm b/OvmfPkg/ResetVector/Ia16/ResetVectorVtf0.asm
index 9c0b5853a46f..ecf1dbcc2caf 100644
--- a/OvmfPkg/ResetVector/Ia16/ResetVectorVtf0.asm
+++ b/OvmfPkg/ResetVector/Ia16/ResetVectorVtf0.asm
@@ -47,6 +47,28 @@ TIMES (15 - ((guidedStructureEnd - guidedStructureStart + 15) % 16)) DB 0
 ;
 guidedStructureStart:
 
+;
+; SEV-SNP boot support
+;
+; sevSnpBlock:
+;   For the initial boot of SEV-SNP guest, a CPUID and Secrets page must
+;   be reserved by the BIOS at a RAM area defined by SNP_CPUID_BASE and
+;   SNP_SECRETS_BASE. A hypervisor will locate this information using the
+;   SEV-SNP boot block GUID and provide the GPA to the PSP to populate
+;   the memory area with the required information..
+;
+; GUID (SEV-SNP boot block): bd39c0c2-2f8e-4243-83e8-1b74cebcb7d9
+;
+sevSnpBootBlockStart:
+    DD      SNP_SECRETS_BASE
+    DD      SNP_SECRETS_SIZE
+    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 8a3269cfc212..247f4eb0dc5e 100644
--- a/OvmfPkg/ResetVector/ResetVector.nasmb
+++ b/OvmfPkg/ResetVector/ResetVector.nasmb
@@ -89,5 +89,9 @@
   %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)
+  %define SNP_SECRETS_BASE  FixedPcdGet32 (PcdOvmfSnpSecretsBase)
+  %define SNP_SECRETS_SIZE  FixedPcdGet32 (PcdOvmfSnpSecretsSize)
 %include "Ia16/ResetVectorVtf0.asm"
 
-- 
2.17.1