On Fri, 18 Oct 2019 22:20:30 +0200 Jens Freimann <jfreim...@redhat.com> wrote:
> This adds support for hiding a device to the qbus and qdev APIs. The > first user of this will be the virtio-net failover feature but the API > introduced with this patch could be used to implement other features as > well, for example hiding pci devices when a pci bus is powered off. > > qdev_device_add() is modified to check for a net_failover_pair_id > argument in the option string. A DeviceListener callback > should_be_hidden() is added. It can be used by a standby device to > inform qdev that this device should not be added now. The standby device > handler can store the device options to plug the device in at a later > point in time. > > One reason for hiding the device is that we don't want to expose both > devices to the guest kernel until the respective virtio feature bit > VIRTIO_NET_F_STANDBY was negotiated and we know that the devices will be > handled correctly by the guest. > > More information on the kernel feature this is using: > https://www.kernel.org/doc/html/latest/networking/net_failover.html > > An example where the primary device is a vfio-pci device and the standby > device is a virtio-net device: > > A device is hidden when it has an "net_failover_pair_id" option, e.g. > > -device virtio-net-pci,...,failover=on,... > -device vfio-pci,...,net_failover_pair_id=net1,... > > Signed-off-by: Jens Freimann <jfreim...@redhat.com> > --- > hw/core/qdev.c | 23 +++++++++++++++++++++++ > include/hw/qdev-core.h | 8 ++++++++ > qdev-monitor.c | 36 +++++++++++++++++++++++++++++++++--- > vl.c | 6 ++++-- > 4 files changed, 68 insertions(+), 5 deletions(-) > > diff --git a/hw/core/qdev.c b/hw/core/qdev.c > index cbad6c1d55..89c134ec53 100644 > --- a/hw/core/qdev.c > +++ b/hw/core/qdev.c > @@ -212,6 +212,29 @@ void device_listener_unregister(DeviceListener *listener) > QTAILQ_REMOVE(&device_listeners, listener, link); > } > > +bool qdev_should_hide_device(QemuOpts *opts) > +{ > + int rc; Initialize to 0? > + DeviceListener *listener; > + > + QTAILQ_FOREACH(listener, &device_listeners, link) { > + if (listener->should_be_hidden) { > + /* should_be_hidden_will return > + * 1 if device matches opts and it should be hidden > + * 0 if device matches opts and should not be hidden > + * -1 if device doesn't match ops > + */ > + rc = listener->should_be_hidden(listener, opts); > + } > + > + if (rc > 0) { > + break; > + } > + } > + > + return rc > 0; > +} > + > void qdev_set_legacy_instance_id(DeviceState *dev, int alias_id, > int required_for_version) > { (...) > +static bool should_hide_device(QemuOpts *opts) > +{ > + if (qemu_opt_foreach(opts, is_failover_device, opts, NULL) == 0) { > + return false; > + } > + return true; > +} I still think you should turn the check around to make it easier to extend in the future, but this is fine as well. (...) With the rc thing changed, Reviewed-by: Cornelia Huck <coh...@redhat.com>