Re: [PATCH v6 2/2] tpm: add backend for mssim

[Stefan Berger <stefanb@linux.ibm.com>]

On 9/22/23 09:02, Daniel P. Berrangé wrote:
> On Fri, Sep 22, 2023 at 08:41:19AM -0400, Stefan Berger wrote:
>> On 9/22/23 02:00, Markus Armbruster wrote:
>>> Found this cleaning out old mail, sorry for missing it until now!
>>>
>>> I think we owe James a quick decision wether we're willing to take the
>>> feature.  Stefan, thoughts?
>> I thought we discusses it back then. Does it handle snapshotting and
>> migration correctly?
> To quote the patch itself:
>
>    +The mssim backend supports snapshotting and migration, but the state
>    +of the Microsoft Simulator server must be preserved (or the server
>    +kept running) outside of QEMU for restore to be successful.

How does 'it' support snapshotting where the state of the TPM can be 
completely different depending on the snapshot?  I know what it took to 
support this feature with swtpm/libtpms but I don't see the equivalent 
here in this backend driver nor in the TCG reference code that the 
underlying TPM 2 simulator is based upon.

I do not want to stand in the way of it being merged but please 
understand that I will also neither maintain nor fix bugs related to it 
nor its related underlying simulator -- with James being the maintainer 
of it, this should be clear. I have reason why I am saying this and they 
come from dealing with the upstream TPM 2 reference code.

Thanks,

   Stefan


>
> With regards,
> Daniel