Re: [PATCH] tpm: Add driver for TPM over virtio

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

On Fri, Feb 22, 2019 at 11:59:23PM +0200, Jarkko Sakkinen wrote:
> On Fri, Feb 22, 2019 at 02:31:37PM -0700, Jason Gunthorpe wrote:
> > On Fri, Feb 22, 2019 at 04:16:01PM -0500, Michael S. Tsirkin wrote:
> > > On Fri, Feb 22, 2019 at 07:30:16AM -0800, James Bottomley wrote:
> > > > On Thu, 2019-02-21 at 18:14 -0800, David Tolnay wrote:
> > > > > Add a config TCG_VIRTIO_VTPM which enables a driver providing the
> > > > > guest kernel side of TPM over virtio.
> > > > 
> > > > What's the use case for using this over the current non-virtio vTPM?. 
> > > > I always thought virtio was about guest to host transport efficiency,
> > > > but the phsical TPM, being connected over a very slow bus, is about as
> > > > inefficient as you can get in that regard, so why do we need to use
> > > > virtio to drive the virtual one?
> > > 
> > > I can't say for sure about TPM.
> > > 
> > > But generally there are many reasons to do virtio rather than emulating
> > > a hardware device.
> > 
> > We already have a xen 'virtioish' TPM driver, so I don't think there
> > is a good reason to block a virtio driver if someone cares about
> > it. There are enough good reasons to prefer virtio to other options,
> > IMHO.
> > 
> > Provided it meets the general requirements for new virtio stuff you
> > outlined.
> 
> Yeah, absolutely we can consider this.
> 
> For me it boils down to testing and documentation part.
> 
> No plans to merge code that I'm unable to run...
> 
> /Jarkko

I do this sometimes. One can't require samples for all supported
hardware. If I can check that code matches spec, I might settle for
that.

-- 
MST