On 9/28/2021 9:51 AM, David Marchand wrote: > When attaching to an existing mono queue tap, the virtio-user was not > reporting that the virtio device was not properly initialised which > prevented from starting the port later. > > $ ip tuntap add test mode tap > $ dpdk-testpmd --vdev \ > net_virtio_user0,iface=test,path=/dev/vhost-net,queues=2 -- -i > > ... > virtio_user_dev_init_mac(): (/dev/vhost-net) No valid MAC in devargs or > device, use random > vhost_kernel_open_tap(): TUNSETIFF failed: Invalid argument > vhost_kernel_enable_queue_pair(): fail to open tap for vhost kernel > virtio_user_start_device(): (/dev/vhost-net) Failed to start device > ... > Configuring Port 0 (socket 0) > vhost_kernel_open_tap(): TUNSETIFF failed: Invalid argument > vhost_kernel_enable_queue_pair(): fail to open tap for vhost kernel > virtio_set_multiple_queues(): Multiqueue configured but send command > failed, this is too late now... > Fail to start port 0: Invalid argument > Please stop the ports first > Done > > The virtio-user with vhost-kernel backend was going through a lot > of complications to initialise tap fds only when using them. > > For each qp enabled for the first time, a tapfd was created via > TUNSETIFF with unneeded additional steps (see below) and then mapped to > the right qp in the vhost-net backend. > Unneeded steps (as long as it has been done once for the port): > - tap features were queried while this is a constant on a running > system, > - the device name in DPDK was updated, > - the mac address of the tap was set, > > On subsequent qps state change, the vhost-net backend fd mapping was > updated and the associated queue/tapfd were disabled/enabled via > TUNSETQUEUE. > > Now, this patch simplifies the whole logic by keeping all tapfds opened > and in enabled state (from the tap point of view) at all time. > > Unused ioctl defines are removed. > > Tap features are validated earlier to fail initialisation asap. > Tap name discovery and mac address configuration are moved when > configuring qp 0. > > To support attaching to mono queue tap, the virtio-user driver now tries > to attach in multi queue first, then fallbacks to mono queue. > > Finally (but this is more for consistency), VIRTIO_NET_F_MQ feature is > exposed only if the underlying tap supports multi queue. > > Signed-off-by: David Marchand <david.march...@redhat.com>
Do we want to backport this patch? If so can you please provide a fixes tag?
