On Wed, Feb 17, 2021 at 4:26 PM Stefan Hajnoczi <stefa...@redhat.com> wrote:
>
> On Tue, Feb 09, 2021 at 04:37:55PM +0100, Eugenio Pérez wrote:
> > diff --git a/qapi/net.json b/qapi/net.json
> > index c31748c87f..a1cdffb0f9 100644
> > --- a/qapi/net.json
> > +++ b/qapi/net.json
> > @@ -77,6 +77,28 @@
> > ##
> > { 'command': 'netdev_del', 'data': {'id': 'str'} }
> >
> > +##
> > +# @x-vhost-enable-shadow-vq:
> > +#
> > +# Use vhost shadow virtqueue.
>
> Is this command for testing only or do you expect it to be invoked by
> libvirt in production? I think the shadow virtqueue can be an internal
> QEMU feature that is hidden from management tools.
>
I think shadow virtqueue should kick in automatically when live
migration is triggered and the vhost device does not have _F_LOG too.
Maybe something like "prefer shadow vq to vhost logging" could be
exposed, but it is not a thing we have to figure now.
> > +#
> > +# @name: the device name of the virtual network adapter
> > +#
> > +# @enable: true to use he alternate shadow VQ notification path
> > +#
> > +# Returns: Error if failure, or 'no error' for success
> > +#
> > +# Since: 6.0
>
> Is this a generic feature for any vhost or vDPA device? If yes, please
> replace "virtual network adapter" in the doc comment.
>
> Does this only apply to vhost-net devices? If so, please put "vhost-net"
> in the name since there are other non-net vhost devices.
Right, thanks for the catch!
>
> > +#
> > +# Example:
> > +#
> > +# -> { "execute": "x-vhost-enable-shadow-vq", "arguments": {"enable":
> > true} }
>
> Missing "name" field?
Yes, I will fix the example in future revisions.
Thanks!
