static int vhost_net_set_features(struct vhost_net *n, u64 features)
{
	size_t vhost_hlen, sock_hlen, hdr_len;
	int i;

	hdr_len = (features & ((1ULL << VIRTIO_NET_F_MRG_RXBUF) |
			       (1ULL << VIRTIO_F_VERSION_1))) ?
			sizeof(struct virtio_net_hdr_mrg_rxbuf) :
			sizeof(struct virtio_net_hdr);
	if (features & (1 << VHOST_NET_F_VIRTIO_NET_HDR)) {
		/* vhost provides vnet_hdr */
		vhost_hlen = hdr_len;
		sock_hlen = 0;
	} else {
		/* socket provides vnet_hdr */
		vhost_hlen = 0;
		sock_hlen = hdr_len;
	}
	mutex_lock(&n->dev.mutex);
	if ((features & (1 << VHOST_F_LOG_ALL)) &&
	    !vhost_log_access_ok(&n->dev))
		goto out_unlock;

	if ((features & (1ULL << VIRTIO_F_IOMMU_PLATFORM))) {
		if (vhost_init_device_iotlb(&n->dev, true))
			goto out_unlock;
	}

	for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
		mutex_lock(&n->vqs[i].vq.mutex);
		n->vqs[i].vq.acked_features = features;
		n->vqs[i].vhost_hlen = vhost_hlen;
		n->vqs[i].sock_hlen = sock_hlen;
		mutex_unlock(&n->vqs[i].vq.mutex);
	}
	mutex_unlock(&n->dev.mutex);
	return 0;

out_unlock:
	mutex_unlock(&n->dev.mutex);
	return -EFAULT;
}
Unknown