int vhost_net_start(struct vhost_net *net, VirtIODevice *dev) { struct vhost_vring_file file = { }; int r; if (net->dev.acked_features & (1 << VIRTIO_NET_F_MRG_RXBUF)) { tap_set_vnet_hdr_len(net->vc, sizeof(struct virtio_net_hdr_mrg_rxbuf)); } net->dev.nvqs = 2; net->dev.vqs = net->vqs; r = vhost_dev_start(&net->dev, dev); if (r < 0) { return r; } net->vc->info->poll(net->vc, false); qemu_set_fd_handler(net->backend, NULL, NULL, NULL); file.fd = net->backend; for (file.index = 0; file.index < net->dev.nvqs; ++file.index) { r = ioctl(net->dev.control, VHOST_NET_SET_BACKEND, &file); if (r < 0) { r = -errno; goto fail; } } return 0; fail: file.fd = -1; while (--file.index >= 0) { int r = ioctl(net->dev.control, VHOST_NET_SET_BACKEND, &file); assert(r >= 0); } net->vc->info->poll(net->vc, true); vhost_dev_stop(&net->dev, dev); if (net->dev.acked_features & (1 << VIRTIO_NET_F_MRG_RXBUF)) { tap_set_vnet_hdr_len(net->vc, sizeof(struct virtio_net_hdr)); } return r; }