/* Copyright (C) 2009 Red Hat, Inc. * Author: Michael S. Tsirkin * * This work is licensed under the terms of the GNU GPL, version 2. * * virtio-net server in host kernel. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "vhost.h" /* Max number of bytes transferred before requeueing the job. * Using this limit prevents one virtqueue from starving others. */ #define VHOST_NET_WEIGHT 0x80000 enum { VHOST_NET_VQ_RX = 0, VHOST_NET_VQ_TX = 1, VHOST_NET_VQ_MAX = 2, }; enum vhost_net_poll_state { VHOST_NET_POLL_DISABLED = 0, VHOST_NET_POLL_STARTED = 1, VHOST_NET_POLL_STOPPED = 2, }; struct vhost_net { struct vhost_dev dev; struct vhost_virtqueue vqs[VHOST_NET_VQ_MAX]; struct vhost_poll poll[VHOST_NET_VQ_MAX]; /* Tells us whether we are polling a socket for TX. * We only do this when socket buffer fills up. * Protected by tx vq lock. */ enum vhost_net_poll_state tx_poll_state; }; /* Pop first len bytes from iovec. Return number of segments used. */ static int move_iovec_hdr(struct iovec *from, struct iovec *to, size_t len, int iov_count) { int seg = 0; size_t size; while (len && seg < iov_count) { size = min(from->iov_len, len); to->iov_base = from->iov_base; to->iov_len = size; from->iov_len -= size; from->iov_base += size; len -= size; ++from; ++to; ++seg; } return seg; } /* Copy iovec entries for len bytes from iovec. */ static void copy_iovec_hdr(const struct iovec *from, struct iovec *to, size_t len, int iovcount) { int seg = 0; size_t size; while (len && seg < iovcount) { size = min(from->iov_len, len); to->iov_base = from->iov_base; to->iov_len = size; len -= size; ++from; ++to; ++seg; } } /* Caller must have TX VQ lock */ static void tx_poll_stop(struct vhost_net *net) { if (likely(net->tx_poll_state != VHOST_NET_POLL_STARTED)) return; vhost_poll_stop(net->poll + VHOST_NET_VQ_TX); net->tx_poll_state = VHOST_NET_POLL_STOPPED; } /* Caller must have TX VQ lock */ static void tx_poll_start(struct vhost_net *net, struct socket *sock) { if (unlikely(net->tx_poll_state != VHOST_NET_POLL_STOPPED)) return; vhost_poll_start(net->poll + VHOST_NET_VQ_TX, sock->file); net->tx_poll_state = VHOST_NET_POLL_STARTED; } /* Expects to be always run from workqueue - which acts as * read-size critical section for our kind of RCU. */ static void handle_tx(struct vhost_net *net) { struct vhost_virtqueue *vq = &net->dev.vqs[VHOST_NET_VQ_TX]; unsigned out, in, s; int head; struct msghdr msg = { .msg_name = NULL, .msg_namelen = 0, .msg_control = NULL, .msg_controllen = 0, .msg_iov = vq->iov, .msg_flags = MSG_DONTWAIT, }; size_t len, total_len = 0; int err, wmem; size_t hdr_size; struct socket *sock; sock = rcu_dereference_check(vq->private_data, lockdep_is_held(&vq->mutex)); if (!sock) return; wmem = atomic_read(&sock->sk->sk_wmem_alloc); if (wmem >= sock->sk->sk_sndbuf) { mutex_lock(&vq->mutex); tx_poll_start(net, sock); mutex_unlock(&vq->mutex); return; } mutex_lock(&vq->mutex); vhost_disable_notify(vq); if (wmem < sock->sk->sk_sndbuf / 2) tx_poll_stop(net); hdr_size = vq->vhost_hlen; for (;;) { head = vhost_get_vq_desc(&net->dev, vq, vq->iov, ARRAY_SIZE(vq->iov), &out, &in, NULL, NULL); /* On error, stop handling until the next kick. */ if (unlikely(head < 0)) break; /* Nothing new? Wait for eventfd to tell us they refilled. */ if (head == vq->num) { wmem = atomic_read(&sock->sk->sk_wmem_alloc); if (wmem >= sock->sk->sk_sndbuf * 3 / 4) { tx_poll_start(net, sock); set_bit(SOCK_ASYNC_NOSPACE, &sock->flags); break; } if (unlikely(vhost_enable_notify(vq))) { vhost_disable_notify(vq); continue; } break; } if (in) { vq_err(vq, "Unexpected descriptor format for TX: " "out %d, int %d\n", out, in); break; } /* Skip header. TODO: support TSO. */ s = move_iovec_hdr(vq->iov, vq->hdr, hdr_size, out); msg.msg_iovlen = out; len = iov_length(vq->iov, out); /* Sanity check */ if (!len) { vq_err(vq, "Unexpected header len for TX: " "%zd expected %zd\n", iov_length(vq->hdr, s), hdr_size); break; } /* TODO: Check specific error and bomb out unless ENOBUFS? */ err = sock->ops->sendmsg(NULL, sock, &msg, len); if (unlikely(err < 0)) { vhost_discard_vq_desc(vq, 1); tx_poll_start(net, sock); break; } if (err != len) pr_debug("Truncated TX packet: " " len %d != %zd\n", err, len); vhost_add_used_and_signal(&net->dev, vq, head, 0); total_len += len; if (unlikely(total_len >= VHOST_NET_WEIGHT)) { vhost_poll_queue(&vq->poll); break; } } mutex_unlock(&vq->mutex); } static int peek_head_len(struct sock *sk) { struct sk_buff *head; int len = 0; lock_sock(sk); head = skb_peek(&sk->sk_receive_queue); if (head) len = head->len; release_sock(sk); return len; } /* This is a multi-buffer version of vhost_get_desc, that works if * vq has read descriptors only. * @vq - the relevant virtqueue * @datalen - data length we'll be reading * @iovcount - returned count of io vectors we fill * @log - vhost log * @log_num - log offset * returns number of buffer heads allocated, negative on error */ static int get_rx_bufs(struct vhost_virtqueue *vq, struct vring_used_elem *heads, int datalen, unsigned *iovcount, struct vhost_log *log, unsigned *log_num) { unsigned int out, in; int seg = 0; int headcount = 0; unsigned d; int r, nlogs = 0; while (datalen > 0) { if (unlikely(seg >= UIO_MAXIOV)) { r = -ENOBUFS; goto err; } d = vhost_get_vq_desc(vq->dev, vq, vq->iov + seg, ARRAY_SIZE(vq->iov) - seg, &out, &in, log, log_num); if (d == vq->num) { r = 0; goto err; } if (unlikely(out || in <= 0)) { vq_err(vq, "unexpected descriptor format for RX: " "out %d, in %d\n", out, in); r = -EINVAL; goto err; } if (unlikely(log)) { nlogs += *log_num; log += *log_num; } heads[headcount].id = d; heads[headcount].len = iov_length(vq->iov + seg, in); datalen -= heads[headcount].len; ++headcount; seg += in; } heads[headcount - 1].len += datalen; *iovcount = seg; if (unlikely(log)) *log_num = nlogs; return headcount; err: vhost_discard_vq_desc(vq, headcount); return r; } /* Expects to be always run from workqueue - which acts as * read-size critical section for our kind of RCU. */ static void handle_rx_big(struct vhost_net *net) { struct vhost_virtqueue *vq = &net->dev.vqs[VHOST_NET_VQ_RX]; unsigned out, in, log, s; int head; struct vhost_log *vq_log; struct msghdr msg = { .msg_name = NULL, .msg_namelen = 0, .msg_control = NULL, /* FIXME: get and handle RX aux data. */ .msg_controllen = 0, .msg_iov = vq->iov, .msg_flags = MSG_DONTWAIT, }; struct virtio_net_hdr hdr = { .flags = 0, .gso_type = VIRTIO_NET_HDR_GSO_NONE }; size_t len, total_len = 0; int err; size_t hdr_size; struct socket *sock = rcu_dereference(vq->private_data); if (!sock || skb_queue_empty(&sock->sk->sk_receive_queue)) return; mutex_lock(&vq->mutex); vhost_disable_notify(vq); hdr_size = vq->vhost_hlen; vq_log = unlikely(vhost_has_feature(&net->dev, VHOST_F_LOG_ALL)) ? vq->log : NULL; for (;;) { head = vhost_get_vq_desc(&net->dev, vq, vq->iov, ARRAY_SIZE(vq->iov), &out, &in, vq_log, &log); /* On error, stop handling until the next kick. */ if (unlikely(head < 0)) break; /* OK, now we need to know about added descriptors. */ if (head == vq->num) { if (unlikely(vhost_enable_notify(vq))) { /* They have slipped one in as we were * doing that: check again. */ vhost_disable_notify(vq); continue; } /* Nothing new? Wait for eventfd to tell us * they refilled. */ break; } /* We don't need to be notified again. */ if (out) { vq_err(vq, "Unexpected descriptor format for RX: " "out %d, int %d\n", out, in); break; } /* Skip header. TODO: support TSO/mergeable rx buffers. */ s = move_iovec_hdr(vq->iov, vq->hdr, hdr_size, in); msg.msg_iovlen = in; len = iov_length(vq->iov, in); /* Sanity check */ if (!len) { vq_err(vq, "Unexpected header len for RX: " "%zd expected %zd\n", iov_length(vq->hdr, s), hdr_size); break; } err = sock->ops->recvmsg(NULL, sock, &msg, len, MSG_DONTWAIT | MSG_TRUNC); /* TODO: Check specific error and bomb out unless EAGAIN? */ if (err < 0) { vhost_discard_vq_desc(vq, 1); break; } /* TODO: Should check and handle checksum. */ if (err > len) { pr_debug("Discarded truncated rx packet: " " len %d > %zd\n", err, len); vhost_discard_vq_desc(vq, 1); continue; } len = err; err = memcpy_toiovec(vq->hdr, (unsigned char *)&hdr, hdr_size); if (err) { vq_err(vq, "Unable to write vnet_hdr at addr %p: %d\n", vq->iov->iov_base, err); break; } len += hdr_size; vhost_add_used_and_signal(&net->dev, vq, head, len); if (unlikely(vq_log)) vhost_log_write(vq, vq_log, log, len); total_len += len; if (unlikely(total_len >= VHOST_NET_WEIGHT)) { vhost_poll_queue(&vq->poll); break; } } mutex_unlock(&vq->mutex); } /* Expects to be always run from workqueue - which acts as * read-size critical section for our kind of RCU. */ static void handle_rx_mergeable(struct vhost_net *net) { struct vhost_virtqueue *vq = &net->dev.vqs[VHOST_NET_VQ_RX]; unsigned uninitialized_var(in), log; struct vhost_log *vq_log; struct msghdr msg = { .msg_name = NULL, .msg_namelen = 0, .msg_control = NULL, /* FIXME: get and handle RX aux data. */ .msg_controllen = 0, .msg_iov = vq->iov, .msg_flags = MSG_DONTWAIT, }; struct virtio_net_hdr_mrg_rxbuf hdr = { .hdr.flags = 0, .hdr.gso_type = VIRTIO_NET_HDR_GSO_NONE }; size_t total_len = 0; int err, headcount; size_t vhost_hlen, sock_hlen; size_t vhost_len, sock_len; struct socket *sock = rcu_dereference(vq->private_data); if (!sock || skb_queue_empty(&sock->sk->sk_receive_queue)) return; mutex_lock(&vq->mutex); vhost_disable_notify(vq); vhost_hlen = vq->vhost_hlen; sock_hlen = vq->sock_hlen; vq_log = unlikely(vhost_has_feature(&net->dev, VHOST_F_LOG_ALL)) ? vq->log : NULL; while ((sock_len = peek_head_len(sock->sk))) { sock_len += sock_hlen; vhost_len = sock_len + vhost_hlen; headcount = get_rx_bufs(vq, vq->heads, vhost_len, &in, vq_log, &log); /* On error, stop handling until the next kick. */ if (unlikely(headcount < 0)) break; /* OK, now we need to know about added descriptors. */ if (!headcount) { if (unlikely(vhost_enable_notify(vq))) { /* They have slipped one in as we were * doing that: check again. */ vhost_disable_notify(vq); continue; } /* Nothing new? Wait for eventfd to tell us * they refilled. */ break; } /* We don't need to be notified again. */ if (unlikely((vhost_hlen))) /* Skip header. TODO: support TSO. */ move_iovec_hdr(vq->iov, vq->hdr, vhost_hlen, in); else /* Copy the header for use in VIRTIO_NET_F_MRG_RXBUF: * needed because sendmsg can modify msg_iov. */ copy_iovec_hdr(vq->iov, vq->hdr, sock_hlen, in); msg.msg_iovlen = in; err = sock->ops->recvmsg(NULL, sock, &msg, sock_len, MSG_DONTWAIT | MSG_TRUNC); /* Userspace might have consumed the packet meanwhile: * it's not supposed to do this usually, but might be hard * to prevent. Discard data we got (if any) and keep going. */ if (unlikely(err != sock_len)) { pr_debug("Discarded rx packet: " " len %d, expected %zd\n", err, sock_len); vhost_discard_vq_desc(vq, headcount); continue; } if (unlikely(vhost_hlen) && memcpy_toiovecend(vq->hdr, (unsigned char *)&hdr, 0, vhost_hlen)) { vq_err(vq, "Unable to write vnet_hdr at addr %p\n", vq->iov->iov_base); break; } /* TODO: Should check and handle checksum. */ if (vhost_has_feature(&net->dev, VIRTIO_NET_F_MRG_RXBUF) && memcpy_toiovecend(vq->hdr, (unsigned char *)&headcount, offsetof(typeof(hdr), num_buffers), sizeof hdr.num_buffers)) { vq_err(vq, "Failed num_buffers write"); vhost_discard_vq_desc(vq, headcount); break; } vhost_add_used_and_signal_n(&net->dev, vq, vq->heads, headcount); if (unlikely(vq_log)) vhost_log_write(vq, vq_log, log, vhost_len); total_len += vhost_len; if (unlikely(total_len >= VHOST_NET_WEIGHT)) { vhost_poll_queue(&vq->poll); break; } } mutex_unlock(&vq->mutex); } static void handle_rx(struct vhost_net *net) { if (vhost_has_feature(&net->dev, VIRTIO_NET_F_MRG_RXBUF)) handle_rx_mergeable(net); else handle_rx_big(net); } static void handle_tx_kick(struct vhost_work *work) { struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue, poll.work); struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev); handle_tx(net); } static void handle_rx_kick(struct vhost_work *work) { struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue, poll.work); struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev); handle_rx(net); } static void handle_tx_net(struct vhost_work *work) { struct vhost_net *net = container_of(work, struct vhost_net, poll[VHOST_NET_VQ_TX].work); handle_tx(net); } static void handle_rx_net(struct vhost_work *work) { struct vhost_net *net = container_of(work, struct vhost_net, poll[VHOST_NET_VQ_RX].work); handle_rx(net); } static int vhost_net_open(struct inode *inode, struct file *f) { struct vhost_net *n = kmalloc(sizeof *n, GFP_KERNEL); struct vhost_dev *dev; int r; if (!n) return -ENOMEM; dev = &n->dev; n->vqs[VHOST_NET_VQ_TX].handle_kick = handle_tx_kick; n->vqs[VHOST_NET_VQ_RX].handle_kick = handle_rx_kick; r = vhost_dev_init(dev, n->vqs, VHOST_NET_VQ_MAX); if (r < 0) { kfree(n); return r; } vhost_poll_init(n->poll + VHOST_NET_VQ_TX, handle_tx_net, POLLOUT, dev); vhost_poll_init(n->poll + VHOST_NET_VQ_RX, handle_rx_net, POLLIN, dev); n->tx_poll_state = VHOST_NET_POLL_DISABLED; f->private_data = n; return 0; } static void vhost_net_disable_vq(struct vhost_net *n, struct vhost_virtqueue *vq) { if (!vq->private_data) return; if (vq == n->vqs + VHOST_NET_VQ_TX) { tx_poll_stop(n); n->tx_poll_state = VHOST_NET_POLL_DISABLED; } else vhost_poll_stop(n->poll + VHOST_NET_VQ_RX); } static void vhost_net_enable_vq(struct vhost_net *n, struct vhost_virtqueue *vq) { struct socket *sock; sock = rcu_dereference_protected(vq->private_data, lockdep_is_held(&vq->mutex)); if (!sock) return; if (vq == n->vqs + VHOST_NET_VQ_TX) { n->tx_poll_state = VHOST_NET_POLL_STOPPED; tx_poll_start(n, sock); } else vhost_poll_start(n->poll + VHOST_NET_VQ_RX, sock->file); } static struct socket *vhost_net_stop_vq(struct vhost_net *n, struct vhost_virtqueue *vq) { struct socket *sock; mutex_lock(&vq->mutex); sock = rcu_dereference_protected(vq->private_data, lockdep_is_held(&vq->mutex)); vhost_net_disable_vq(n, vq); rcu_assign_pointer(vq->private_data, NULL); mutex_unlock(&vq->mutex); return sock; } static void vhost_net_stop(struct vhost_net *n, struct socket **tx_sock, struct socket **rx_sock) { *tx_sock = vhost_net_stop_vq(n, n->vqs + VHOST_NET_VQ_TX); *rx_sock = vhost_net_stop_vq(n, n->vqs + VHOST_NET_VQ_RX); } static void vhost_net_flush_vq(struct vhost_net *n, int index) { vhost_poll_flush(n->poll + index); vhost_poll_flush(&n->dev.vqs[index].poll); } static void vhost_net_flush(struct vhost_net *n) { vhost_net_flush_vq(n, VHOST_NET_VQ_TX); vhost_net_flush_vq(n, VHOST_NET_VQ_RX); } static int vhost_net_release(struct inode *inode, struct file *f) { struct vhost_net *n = f->private_data; struct socket *tx_sock; struct socket *rx_sock; vhost_net_stop(n, &tx_sock, &rx_sock); vhost_net_flush(n); vhost_dev_cleanup(&n->dev); if (tx_sock) fput(tx_sock->file); if (rx_sock) fput(rx_sock->file); /* We do an extra flush before freeing memory, * since jobs can re-queue themselves. */ vhost_net_flush(n); kfree(n); return 0; } static struct socket *get_raw_socket(int fd) { struct { struct sockaddr_ll sa; char buf[MAX_ADDR_LEN]; } uaddr; int uaddr_len = sizeof uaddr, r; struct socket *sock = sockfd_lookup(fd, &r); if (!sock) return ERR_PTR(-ENOTSOCK); /* Parameter checking */ if (sock->sk->sk_type != SOCK_RAW) { r = -ESOCKTNOSUPPORT; goto err; } r = sock->ops->getname(sock, (struct sockaddr *)&uaddr.sa, &uaddr_len, 0); if (r) goto err; if (uaddr.sa.sll_family != AF_PACKET) { r = -EPFNOSUPPORT; goto err; } return sock; err: fput(sock->file); return ERR_PTR(r); } static struct socket *get_tap_socket(int fd) { struct file *file = fget(fd); struct socket *sock; if (!file) return ERR_PTR(-EBADF); sock = tun_get_socket(file); if (!IS_ERR(sock)) return sock; sock = macvtap_get_socket(file); if (IS_ERR(sock)) fput(file); return sock; } static struct socket *get_socket(int fd) { struct socket *sock; /* special case to disable backend */ if (fd == -1) return NULL; sock = get_raw_socket(fd); if (!IS_ERR(sock)) return sock; sock = get_tap_socket(fd); if (!IS_ERR(sock)) return sock; return ERR_PTR(-ENOTSOCK); } static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd) { struct socket *sock, *oldsock; struct vhost_virtqueue *vq; int r; mutex_lock(&n->dev.mutex); r = vhost_dev_check_owner(&n->dev); if (r) goto err; if (index >= VHOST_NET_VQ_MAX) { r = -ENOBUFS; goto err; } vq = n->vqs + index; mutex_lock(&vq->mutex); /* Verify that ring has been setup correctly. */ if (!vhost_vq_access_ok(vq)) { r = -EFAULT; goto err_vq; } sock = get_socket(fd); if (IS_ERR(sock)) { r = PTR_ERR(sock); goto err_vq; } /* start polling new socket */ oldsock = rcu_dereference_protected(vq->private_data, lockdep_is_held(&vq->mutex)); if (sock != oldsock) { vhost_net_disable_vq(n, vq); rcu_assign_pointer(vq->private_data, sock); vhost_net_enable_vq(n, vq); } mutex_unlock(&vq->mutex); if (oldsock) { vhost_net_flush_vq(n, index); fput(oldsock->file); } mutex_unlock(&n->dev.mutex); return 0; err_vq: mutex_unlock(&vq->mutex); err: mutex_unlock(&n->dev.mutex); return r; } static long vhost_net_reset_owner(struct vhost_net *n) { struct socket *tx_sock = NULL; struct socket *rx_sock = NULL; long err; mutex_lock(&n->dev.mutex); err = vhost_dev_check_owner(&n->dev); if (err) goto done; vhost_net_stop(n, &tx_sock, &rx_sock); vhost_net_flush(n); err = vhost_dev_reset_owner(&n->dev); done: mutex_unlock(&n->dev.mutex); if (tx_sock) fput(tx_sock->file); if (rx_sock) fput(rx_sock->file); return err; } 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 & (1 << VIRTIO_NET_F_MRG_RXBUF)) ? 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)) { mutex_unlock(&n->dev.mutex); return -EFAULT; } n->dev.acked_features = features; smp_wmb(); for (i = 0; i < VHOST_NET_VQ_MAX; ++i) { mutex_lock(&n->vqs[i].mutex); n->vqs[i].vhost_hlen = vhost_hlen; n->vqs[i].sock_hlen = sock_hlen; mutex_unlock(&n->vqs[i].mutex); } vhost_net_flush(n); mutex_unlock(&n->dev.mutex); return 0; } static long vhost_net_ioctl(struct file *f, unsigned int ioctl, unsigned long arg) { struct vhost_net *n = f->private_data; void __user *argp = (void __user *)arg; u64 __user *featurep = argp; struct vhost_vring_file backend; u64 features; int r; switch (ioctl) { case VHOST_NET_SET_BACKEND: if (copy_from_user(&backend, argp, sizeof backend)) return -EFAULT; return vhost_net_set_backend(n, backend.index, backend.fd); case VHOST_GET_FEATURES: features = VHOST_FEATURES; if (copy_to_user(featurep, &features, sizeof features)) return -EFAULT; return 0; case VHOST_SET_FEATURES: if (copy_from_user(&features, featurep, sizeof features)) return -EFAULT; if (features & ~VHOST_FEATURES) return -EOPNOTSUPP; return vhost_net_set_features(n, features); case VHOST_RESET_OWNER: return vhost_net_reset_owner(n); default: mutex_lock(&n->dev.mutex); r = vhost_dev_ioctl(&n->dev, ioctl, arg); vhost_net_flush(n); mutex_unlock(&n->dev.mutex); return r; } } #ifdef CONFIG_COMPAT static long vhost_net_compat_ioctl(struct file *f, unsigned int ioctl, unsigned long arg) { return vhost_net_ioctl(f, ioctl, (unsigned long)compat_ptr(arg)); } #endif static const struct file_operations vhost_net_fops = { .owner = THIS_MODULE, .release = vhost_net_release, .unlocked_ioctl = vhost_net_ioctl, #ifdef CONFIG_COMPAT .compat_ioctl = vhost_net_compat_ioctl, #endif .open = vhost_net_open, .llseek = noop_llseek, }; static struct miscdevice vhost_net_misc = { MISC_DYNAMIC_MINOR, "vhost-net", &vhost_net_fops, }; static int vhost_net_init(void) { return misc_register(&vhost_net_misc); } module_init(vhost_net_init); static void vhost_net_exit(void) { misc_deregister(&vhost_net_misc); } module_exit(vhost_net_exit); MODULE_VERSION("0.0.1"); MODULE_LICENSE("GPL v2"); MODULE_AUTHOR("Michael S. Tsirkin"); MODULE_DESCRIPTION("Host kernel accelerator for virtio net");