On Fri, 2023-09-22 at 09:27 -0400, Stefan Berger wrote: > > 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?
In the same way we support things like external disk devices across snapshot and migration: it's up to the owner of the device to preserve the state for the next resume. If you muck with the state (or connect the wrong device) all bets are off. > 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. I already said I'll support this, and added a Maintainers entry and a specific exclusion from your TPM maintainer entry. I'm not sure what additional assurances I can give? James