More questions / comments

1.1 "Get TPM AK Cert (signed by EK)". This is something I thought for
a long time too. That's not what the EK does. The EK does not sign
anything. It's used for proving ownership of both EK and AK for
ActivateCredential to get an AKcert from a trusted CA.
What is your intended communication channel between SVSM and a CA for
this credential activation?

2.2.2 item 6, migration needs to ensure that the vTPM state is not
duplicated, which is a possible host attack by spinning up two targets
and directing migration to both. This needs to be explicitly required
for TPM security.
2.2.3 item 8 I don't think the community has fully agreed that MMIO
should be the command pathway for SVSM-based vTPM due to performance
problems. This appears to disallow an SVSM service call implementation
as an enlightenment path.
2.4 the alternate entrypoint TD_PARAM is undocumented. Please add a
footnote that this will be in a future revision to the TDX module
reference.
item 2.1 The launch parameter (TD_HOB) is currently measured to MRTD,
so how is this data communicated to SVSM if it's meant to be measured
to RTMR[0] (and be a useful measurement, presumably because it wasn't
measured to MRTD?)

2.5.2 "TPM CRB interface attack" and "TPM command attack" could use
citations for what you mean.

On Fri, Aug 2, 2024 at 8:40 AM James Bottomley
[off-list ref] wrote:

On Thu, 2024-08-01 at 22:38 +0000, Yao, Jiewen wrote:

quoted

Hi
As follow up, we have drafted the vTPM document and put to
https://github.com/intel-staging/td-partitioning-svsm/blob/svsm-tdp-vtpm/Documentation/TD%20Partitioning%20based%20virtual%20TPM%20Design%20Guide%20Rev%200.5.1.pdf
.

Just a note for the vTPM reference implementation which, I think,
applies to both you and the current SVSM-vTPM: the reference TPM
implementation has moved to

https://github.com/TrustedComputingGroup/TPM

And the one you list (https://github.com/microsoft/ms-tpm-20-ref) is
now a stale copy that isn't being kept up to date.

Regards,

James

-- 
-Dionna Glaze, PhD, CISSP, CCSP (she/her)