Re: [virtio-dev] Re: guest / host buffer sharing ...

[David Stevens <stevensd@chromium.org>]

> > > Of course only virtio drivers would try step (2), other drivers (when
> > > sharing buffers between intel gvt device and virtio-gpu for example)
> > > would go straight to (3).
> >
> > For virtio-gpu as it is today, it's not clear to me that they're
> > equivalent. As I read it, the virtio-gpu spec makes a distinction
> > between the guest memory and the host resource. If virtio-gpu is
> > communicating with non-virtio devices, then obviously you'd just be
> > working with guest memory. But if it's communicating with another
> > virtio device, then there are potentially distinct guest and host
> > buffers that could be used. The spec shouldn't leave any room for
> > ambiguity as to how this distinction is handled.
>
> Yep.  It should be the host side buffer.

I agree that it should be the host side buffer. I just want to make
sure that the meaning of 'import' is clear, and to establish the fact
that importing a buffer by uuid is not necessarily the same thing as
creating a new buffer in a different device from the same sglist (for
example, sharing a guest sglist might require more flushes).

-David