QE uses the sim_vdpa device to test this patch and add "ctrl_vq=off" in the qemu command line. Guest can find this device, there are no any error messages in guest dmesg, and can migrate successfully.
Tested-by: Lei Yang <leiy...@redhat.com> Eugenio Perez Martin <epere...@redhat.com> 于2023年2月14日周二 14:53写道: > > On Tue, Jan 24, 2023 at 5:32 PM Eugenio Pérez <epere...@redhat.com> wrote: > > > > Since GUEST_ANNOUNCE is emulated the feature bit could be set without > > backend support. This happens in the vDPA case. > > > > However, backend vDPA parent may not have CVQ support. This causes an > > incoherent feature set, and the driver may refuse to start. This > > happens in virtio-net Linux driver. > > > > This may be solved differently in the future. Qemu is able to emulate a > > CVQ just for guest_announce purposes, helping guest to notify the new > > location with vDPA devices that does not support it. However, this is > > left as a TODO as it is way more complex to backport. > > > > Tested with vdpa_net_sim, toggling manually VIRTIO_NET_F_CTRL_VQ in the > > driver and migrating it with x-svq=on. > > > > Friendly ping about this patch, as it fell through the cracks if I'm not > wrong. > > Thanks! > > > Fixes: 980003debddd ("vdpa: do not handle VIRTIO_NET_F_GUEST_ANNOUNCE in > > vhost-vdpa") > > Reported-by: Dawar, Gautam <gautam.da...@amd.com> > > Signed-off-by: Eugenio Pérez <epere...@redhat.com> > > --- > > hw/net/virtio-net.c | 15 +++++++++++++++ > > 1 file changed, 15 insertions(+) > > > > diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c > > index 3ae909041a..09d5c7a664 100644 > > --- a/hw/net/virtio-net.c > > +++ b/hw/net/virtio-net.c > > @@ -820,6 +820,21 @@ static uint64_t virtio_net_get_features(VirtIODevice > > *vdev, uint64_t features, > > features |= (1ULL << VIRTIO_NET_F_MTU); > > } > > > > + /* > > + * Since GUEST_ANNOUNCE is emulated the feature bit could be set > > without > > + * enabled. This happens in the vDPA case. > > + * > > + * Make sure the feature set is not incoherent, as the driver could > > refuse > > + * to start. > > + * > > + * TODO: QEMU is able to emulate a CVQ just for guest_announce > > purposes, > > + * helping guest to notify the new location with vDPA devices that > > does not > > + * support it. > > + */ > > + if (!virtio_has_feature(vdev->backend_features, VIRTIO_NET_F_CTRL_VQ)) > > { > > + virtio_clear_feature(&features, VIRTIO_NET_F_GUEST_ANNOUNCE); > > + } > > + > > return features; > > } > > > > -- > > 2.31.1 > > > > >