Re: [PATCH v5 2/3] acpi: tpm: Add missing device identification objects

["Michael S. Tsirkin" <mst@redhat.com>]

On Thu, Jan 06, 2022 at 08:53:00AM -0500, Stefan Berger wrote:
> 
> On 1/6/22 03:36, Igor Mammedov wrote:
> > On Tue,  4 Jan 2022 12:58:05 -0500
> > Stefan Berger <stefanb@linux.ibm.com> wrote:
> > 
> > > Add missing TPM device identification objects _STR and _UID. They will
> > > appear as files 'description' and 'uid' under Linux sysfs.
> > > 
> > > Following inspection of sysfs entries for hardware TPMs we chose
> > > uid '1'.
> > My guess would be that buy default (in case of missing UID), OSPM
> > will start enumerate from 0. So I think 0 is more safer choice
> > when it comes to compatibility.
> > 
> > Can you smoke test TPM with Windows, and check if adding UID doesn't
> > break anything if VM actually uses TMP (though I'm not sure how to
> > check it on Windows, maybe install Windows 11 without this patch
> > and then see if it still boots pre-installed VM and nothing is broken
> > after this patch)?
> > 
> I smoke tested it with the posted patches applied to v6.2.0 and started 3
> VMs with it:
> 
> - Linux shows uid = 1 and the description "TPM 2.0 Device" in sysfs
> 
> - Win 10 and Win 11 tpm.msc tool are both showing that the TPM is 'ready for
> use'
> 
>     Stefan
> 

Just to make sure, what Igor was concerned about is issues like
we had with e.g. network devices, when changing UID makes
windows think it's a new device and lose configuration
created on old qemu on boot with a new qemu.
Not sure what can be configured with a TPM device though ...

-- 
MST