May I ask to use the OvmfMetadata instead of the of TdxMetadata for the Guided structure name label (same as what I did in SNP series patch #4). If you can send the metadata introduction as a patch separately then add the TDX descriptor in TDX series. I can try to make it work for the SNP series and add SNP specific descriptors. Additionally, I think you want to provide an absolute offset for the start of the metadata instead relative value so that VMM can very easily reach to the start of metadata.

e.g

+OvmfMetadataOffsetStart:
+ DD      (fourGigabytes - OvmfMetadataGuid - 16)
+ DW      OvmfMetadataOffsetEnd - OvmfMetadataOffsetStart
+ DB      0x35, 0x65, 0x7a, 0xe4, 0x4a, 0x98, 0x98, 0x47
+ DB      0x86, 0x5e, 0x46, 0x85, 0xa7, 0xbf, 0x8e, 0xc2
+OvmfMetadataOffsetEnd:

For SNP series, I will 3 section types #1 CPUID, # Secrets, and #3 SEC_MEM and will probably add a total of 3 more descriptors.

From: Xu, Min M <min.m.xu@intel.com>
Sent: Tuesday, September 28, 2021 2:35 AM
To: devel@edk2.groups.io <devel@edk2.groups.io>; kraxel@redhat.com <kraxel@redhat.com>
Cc: Yao, Jiewen <jiewen.yao@intel.com>; Ard Biesheuvel <ardb+tianocore@kernel.org>; Justen, Jordan L <jordan.l.justen@intel.com>; Singh, Brijesh <brijesh.singh@amd.com>; Erdem Aktas <erdemaktas@google.com>; James Bottomley <jejb@linux.ibm.com>; Lendacky, Thomas <Thomas.Lendacky@amd.com>
Subject: RE: [edk2-devel] [PATCH V8 3/3] OvmfPkg: Enable TDX in ResetVector

On September 28, 2021 12:43 PM, Gerd Hoffmann wrote:
> Hi,
>
> > > Can you move the metadata changes to a separate patch please?
> > Yes, the metadata changes will be in a separate patch in the next version.
>
> Can you also add a comment block documenting the format? Not only those
> parts which are used for TDVF, but everything? The description in tdx-virtual-
> firmware-design-guide-rev-1.pdf seems to be incomplete, specifically the
> option to use the table for TD memory allocation (as mentioned by Jiewen) is
> not covered. And possibly there is more which is missing ...
Sure. I will add the comment in IntelTdxMetadata.asm to describe the format of Tdx Metadata.
Here is the PR I would send as the next version. https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Ftianocore%2Fedk2%2Fpull%2F2018&data=04%7C01%7Cbrijesh.singh%40amd.com%7Cf49ea5bc7d79474e572108d982529cbd%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637684113590273535%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=bGOxYMIKtHYKhcfk0Wt4qoIgiz3b9DM%2FAD%2Fui3ByVrU%3D&reserved=0
You can have a preliminary review if you want.
>
> thanks,
> Gerd
>
>
>
>
>