Linux Virtualization - Oct 2021 - [virtio-dev] Re: [RFC PATCH 1/1] virtio: write back features before verify

On Mon, 4 Oct 2021 16:01:12 -0400
"Michael S. Tsirkin" <mst at redhat.com> wrote:
> > 
> > Ok, so what about something like
> > 
> > "If FEATURES_OK is not set, the driver MAY change the set of
features it
> > accepts."
> > 
> > in the device initialization section?  
> 
> Maybe "as long as". However Halil implied that some features are
not
> turned off properly if that happens. Halil could you pls provide
> some examples?


static void virtio_net_set_features(VirtIODevice *vdev, uint64_t features)
{
...
    if (virtio_has_feature(features, VIRTIO_NET_F_STANDBY)) {
        qapi_event_send_failover_negotiated(n->netclient_name);
        qatomic_set(&n->failover_primary_hidden, false);
        failover_add_primary(n, &err);
        if (err) {
            warn_report_err(err);
        }
    }
}

This is probably the only one in QEMU. Back then I stopped looking
after the first hit.

Regards,
Halil

On Tue, Oct 05, 2021 at 01:17:51PM +0200, Halil Pasic
wrote:
> On Mon, 4 Oct 2021 16:01:12 -0400
> "Michael S. Tsirkin" <mst at redhat.com> wrote:
> 
> > > 
> > > Ok, so what about something like
> > > 
> > > "If FEATURES_OK is not set, the driver MAY change the set of
features it
> > > accepts."
> > > 
> > > in the device initialization section?  
> > 
> > Maybe "as long as". However Halil implied that some features
are not
> > turned off properly if that happens. Halil could you pls provide
> > some examples?
> 
> 
> 
> static void virtio_net_set_features(VirtIODevice *vdev, uint64_t features)
> {
> ...
>     if (virtio_has_feature(features, VIRTIO_NET_F_STANDBY)) {
>         qapi_event_send_failover_negotiated(n->netclient_name);
>         qatomic_set(&n->failover_primary_hidden, false);
>         failover_add_primary(n, &err);
>         if (err) {
>             warn_report_err(err);
>         }
>     }
> }
> 
> This is probably the only one in QEMU. Back then I stopped looking
> after the first hit.
> 
> Regards,
> Halil
Hmm ok more failover issues :(
This stuff really should be moved to set_status.

-- 
MST