Re: [Qemu-devel] [PATCH 0/5] tpm: Extend the TPM TIS implementation

[Stefan Berger]

On 12/09/2014 09:45 AM, Michael S. Tsirkin wrote:
> On Tue, Dec 09, 2014 at 09:40:28AM -0500, Stefan Berger wrote:
> > On 12/09/2014 09:35 AM, Michael S. Tsirkin wrote:
> > > On Tue, Dec 09, 2014 at 09:18:54AM -0500, Stefan Berger wrote:
> > > > The following series of patches extends the TPM TIS implementation to
> > > > version 1.3. This will lead to a TIS version that supports TPM 2.
> > > > For this I would post relatively small patches afterwards.
> > > >
> > > > Regards,
> > > >     Stefan
> > > Since this is guest visible, should this be limited
> > > to new machine types, to avoid breaking migrating
> > > guests across hypervisor versions?
> > Migration is not currently possible with TPM, since TPM (passthrough) is
> > preventing it.
> >
> >      Stefan
> OK, for live migration, fair enough.
>
> For off-line migration: will the following still work:
>         - boot guest with tpm 1.3. use tpm in some way
>         - halt, start guest on old qemu with tpm 1.2
> ?

So this is not a suspend resume operation ? Sure, it will work if the 
driver the OS is using works with a TPM TIS 1.3 interface and also with 
a TPM TIS 1.2 interface.

      Stefan