[PATCH v2] OvmfPkg/AmdSevDxe: Update ConfidentialComputing blob struct definition

Michael Roth <michael.roth@...>

The Confidential Computing blob defined here is intended to match the
definition defined by linux guest kernel. Previously, both definitions
relied on natural alignment, but that relies on both OVMF and kernel
being compiled as 64-bit. While there aren't currently any plans to
enable SNP support for 32-bit compilations, the kernel definition has
since been updated to use explicit padding/reserved fields to avoid
this dependency. Update OVMF to match that definition.

While at it, also fix up the Reserved fields to match the numbering
used in the kernel.

No functional changes (for currently-supported environments, at least).

Reviewed-by: Tom Lendacky <thomas.lendacky@...>
Signed-off-by: Michael Roth <michael.roth@...>
- Update commit message to clarify why Reserved fields are renamed

OvmfPkg/AmdSevDxe/AmdSevDxe.c | 2 ++
OvmfPkg/Include/Guid/ConfidentialComputingSevSnpBlob.h | 6 ++++--
2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/OvmfPkg/AmdSevDxe/AmdSevDxe.c b/OvmfPkg/AmdSevDxe/AmdSevDxe.c
index 662d3c4ccb..ee6d2528d9 100644
--- a/OvmfPkg/AmdSevDxe/AmdSevDxe.c
+++ b/OvmfPkg/AmdSevDxe/AmdSevDxe.c
(UINT64)(UINTN)FixedPcdGet32 (PcdOvmfSnpSecretsBase),
FixedPcdGet32 (PcdOvmfSnpSecretsSize),
+ 0,
(UINT64)(UINTN)FixedPcdGet32 (PcdOvmfCpuidBase),
FixedPcdGet32 (PcdOvmfCpuidSize),
+ 0,

diff --git a/OvmfPkg/Include/Guid/ConfidentialComputingSevSnpBlob.h b/OvmfPkg/Include/Guid/ConfidentialComputingSevSnpBlob.h
index b328310fd0..83620e31b8 100644
--- a/OvmfPkg/Include/Guid/ConfidentialComputingSevSnpBlob.h
+++ b/OvmfPkg/Include/Guid/ConfidentialComputingSevSnpBlob.h
@@ -18,14 +18,16 @@
{ 0x85, 0x54, 0x93, 0xd7, 0x77, 0x91, 0x2d, 0x42 }, \

-typedef struct {
+typedef PACKED struct {
UINT32 Header;
UINT16 Version;
- UINT16 Reserved1;
+ UINT16 Reserved;
UINT64 SecretsPhysicalAddress;
UINT32 SecretsSize;
+ UINT32 Reserved1;
UINT64 CpuidPhysicalAddress;
UINT32 CpuidLSize;
+ UINT32 Reserved2;

extern EFI_GUID gConfidentialComputingSevSnpBlobGuid;