From f3a8505656935cde32e28c1c6317f725084da1e0 Mon Sep 17 00:00:00 2001 From: Jens Freimann Date: Tue, 29 Oct 2019 12:48:55 +0100 Subject: qdev/qbus: add hidden device support 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 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 "failover_pair_id" option, e.g. -device virtio-net-pci,...,failover=on,... -device vfio-pci,...,failover_pair_id=net1,... Signed-off-by: Jens Freimann Message-Id: <20191029114905.6856-2-jfreimann@redhat.com> Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin --- hw/core/qdev.c | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) (limited to 'hw/core/qdev.c') diff --git a/hw/core/qdev.c b/hw/core/qdev.c index cbad6c1d55..3b8d43d0fd 100644 --- a/hw/core/qdev.c +++ b/hw/core/qdev.c @@ -212,6 +212,30 @@ void device_listener_unregister(DeviceListener *listener) QTAILQ_REMOVE(&device_listeners, listener, link); } +bool qdev_should_hide_device(QemuOpts *opts) +{ + int rc = -1; + 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) { -- cgit 1.4.1