On Thu, Oct 20, 2022 at 6:30 AM Jason Wang <jasow...@redhat.com> wrote:
>
> On Wed, Oct 19, 2022 at 8:52 PM Eugenio Pérez <epere...@redhat.com> wrote:
> >
> > At this moment this code path is not reached, but vdpa devices can offer
> > VIRTIO_NET_F_STATUS unconditionally.
>
> So I guess what you mean is that, for the parent that doesn't support
> VIRTIO_NET_F_STATUS, emulate one for making sure the ANNOUCNE to work.
> This is safe since the spec said the driver will assume the link is
> always up if without this feature.
>
Right.
> > While the guest must assume that
> > link is always up by the standard, qemu will set the status bit to 1
> > always in this case.
> >
> > This makes little use by itself, but VIRTIO_NET_F_STATUS is needed for
> > the guest to read status bit VIRTIO_NET_F_GUEST_ANNOUNCE, used by feature
> > VIRTIO_NET_F_GUEST_ANNOUNCE. So qemu must emulate status feature in case
> > it needs to emulate the guest announce feature.
> >
> > Signed-off-by: Eugenio Pérez <epere...@redhat.com>
> > ---
> > hw/net/vhost_net.c | 27 ++++++++++++++++++++++++++-
> > 1 file changed, 26 insertions(+), 1 deletion(-)
> >
> > diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c
> > index d28f8b974b..5660606c1d 100644
> > --- a/hw/net/vhost_net.c
> > +++ b/hw/net/vhost_net.c
> > @@ -117,7 +117,32 @@ uint64_t vhost_net_get_features(struct vhost_net *net,
> > uint64_t features)
> > int vhost_net_get_config(struct vhost_net *net, uint8_t *config,
> > uint32_t config_len)
> > {
> > - return vhost_dev_get_config(&net->dev, config, config_len, NULL);
> > + VirtIODevice *vdev;
> > + int r = vhost_dev_get_config(&net->dev, config, config_len, NULL);
> > +
> > + if (unlikely(r != 0)) {
> > + return r;
> > + }
> > +
> > + if (config_len < endof(struct virtio_net_config, status)) {
> > + return 0;
> > + }
> > +
> > + /*
> > + * TODO: Perform this only if vhost_vdpa.
> > + */
>
> Cindy adds some mediation codes for vhost-vDPA in
> virtio_net_get_config(), so I believe it can be done there?
>
Sure, let me take a look.
Thanks!
> Thanks
>
> > + vdev = net->dev.vdev;
> > + if (!vdev) {
> > + /* Device is starting */
> > + return 0;
> > + }
> > +
> > + if ((net->dev.acked_features & BIT_ULL(VIRTIO_NET_F_STATUS)) &&
> > + !(net->dev.features & BIT_ULL(VIRTIO_NET_F_STATUS))) {
> > + ((struct virtio_net_config *)config)->status |=
> > VIRTIO_NET_S_LINK_UP;
> > + }
> > +
> > + return 0;
> > }
> > int vhost_net_set_config(struct vhost_net *net, const uint8_t *data,
> > uint32_t offset, uint32_t size, uint32_t flags)
> > --
> > 2.31.1
> >
>
