Re: [PATCH] acpi: Add TPM2 interface definition and make the TPM version configurable.

[Jason Andryuk <jandryuk@xxxxxxxxx>]

On Tue, Aug 30, 2022 at 4:30 PM Jennifer Herbert
<jennifer.herbert@xxxxxxxxxx> wrote:
>
> This patch introduces an optional TPM 2 interface definition to the ACPI 
> table,
> which is to be used as part of a vTPM 2 implementation.
> To enable the new interface - I have made the TPM interface version
> configurable in the acpi_config, with the default being the existing 
> 1.2.(TCPA)
> I have also added to hvmloader an option to utilise this new config, which can
> be triggered by setting the platform/tpm_verion xenstore key.
>
> Signed-off-by: Jennifer Herbert <jennifer.herbert@xxxxxxxxxx>

Reviewed-by: Jason Andryuk <jandryuk@xxxxxxxxx>

Thanks.

Is there a particular reason why CRB (Command Response Buffer) was
chosen over TIS (TPM Interface Specification)?  I think of CRB as more
of an embedded device TPM interface, and TIS is what is usually used
with physical TPMs.  My experiences have only been with TIS devices,
so that is influencing my outlook.  Hmm, this patch seems to reference
the Intel Platform Trust Technology (PTT) fTPM (firmware-TPM) as using
the CRB interface:
https://patchwork.kernel.org/project/tpmdd-devel/patch/1417672167-3489-8-git-send-email-jarkko.sakkinen@xxxxxxxxxxxxxxx/
 If PTT fTPMs are using CRB, then it's more than just embedded
devices..

Regards,
Jason