Re: [PATCH v3 0/2] tpm: add mssim backend

[James Bottomley]

On Mon, 2022-12-19 at 10:16 -0500, Stefan Berger wrote:
> 
> 
> On 12/19/22 08:13, James Bottomley wrote:
> > From: James Bottomley <James.Bottomley@HansenPartnership.com>
> > 
> > The requested feedback was to convert the tpmdev handler to being
> > json
> > based, which requires rethreading all the backends.  The good news
> > is
> > this reduced quite a bit of code (especially as I converted it to
> > error_fatal handling as well, which removes the return status
> > threading).  The bad news is I can't test any of the conversions.
> > swtpm still isn't building on opensuse and, apparently, passthrough
> > doesn't like my native TPM because it doesn't allow cancellation.
> 
> For passthrough you can use /dev/null in place of the cancel file.
> Libvirt does that also:
> 
> https://github.com/stefanberger/libvirt-tpm/blob/master/src/util/virtpm.c#L88

OK, so passthrough works with the visitor conversion.  If /dev/null is
the default for no cancel path, the backend shouldn't really beat the
end user up about not specifying it if it can't find the cancel path
for the chosen host TPM.

James