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linux-sg2042/drivers/vhost/net.c

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/* Copyright (C) 2009 Red Hat, Inc.
* Author: Michael S. Tsirkin <mst@redhat.com>
*
* This work is licensed under the terms of the GNU GPL, version 2.
*
* virtio-net server in host kernel.
*/
#include <linux/compat.h>
#include <linux/eventfd.h>
#include <linux/vhost.h>
#include <linux/virtio_net.h>
#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/mutex.h>
#include <linux/workqueue.h>
#include <linux/file.h>
#include <linux/slab.h>
#include <linux/sched/clock.h>
#include <linux/sched/signal.h>
#include <linux/vmalloc.h>
#include <linux/net.h>
#include <linux/if_packet.h>
#include <linux/if_arp.h>
#include <linux/if_tun.h>
#include <linux/if_macvlan.h>
#include <linux/if_tap.h>
#include <linux/if_vlan.h>
#include <linux/skb_array.h>
#include <linux/skbuff.h>
#include <net/sock.h>
#include <net/xdp.h>
#include "vhost.h"
static int experimental_zcopytx = 1;
module_param(experimental_zcopytx, int, 0444);
MODULE_PARM_DESC(experimental_zcopytx, "Enable Zero Copy TX;"
" 1 -Enable; 0 - Disable");
/* Max number of bytes transferred before requeueing the job.
* Using this limit prevents one virtqueue from starving others. */
#define VHOST_NET_WEIGHT 0x80000
/* Max number of packets transferred before requeueing the job.
* Using this limit prevents one virtqueue from starving others with small
* pkts.
*/
#define VHOST_NET_PKT_WEIGHT 256
/* MAX number of TX used buffers for outstanding zerocopy */
#define VHOST_MAX_PEND 128
#define VHOST_GOODCOPY_LEN 256
/*
* For transmit, used buffer len is unused; we override it to track buffer
* status internally; used for zerocopy tx only.
*/
/* Lower device DMA failed */
#define VHOST_DMA_FAILED_LEN ((__force __virtio32)3)
/* Lower device DMA done */
#define VHOST_DMA_DONE_LEN ((__force __virtio32)2)
/* Lower device DMA in progress */
#define VHOST_DMA_IN_PROGRESS ((__force __virtio32)1)
/* Buffer unused */
#define VHOST_DMA_CLEAR_LEN ((__force __virtio32)0)
#define VHOST_DMA_IS_DONE(len) ((__force u32)(len) >= (__force u32)VHOST_DMA_DONE_LEN)
enum {
VHOST_NET_FEATURES = VHOST_FEATURES |
(1ULL << VHOST_NET_F_VIRTIO_NET_HDR) |
(1ULL << VIRTIO_NET_F_MRG_RXBUF) |
(1ULL << VIRTIO_F_IOMMU_PLATFORM)
};
enum {
VHOST_NET_VQ_RX = 0,
VHOST_NET_VQ_TX = 1,
VHOST_NET_VQ_MAX = 2,
};
struct vhost_net_ubuf_ref {
/* refcount follows semantics similar to kref:
* 0: object is released
* 1: no outstanding ubufs
* >1: outstanding ubufs
*/
atomic_t refcount;
wait_queue_head_t wait;
struct vhost_virtqueue *vq;
};
#define VHOST_NET_BATCH 64
struct vhost_net_buf {
void **queue;
int tail;
int head;
};
struct vhost_net_virtqueue {
struct vhost_virtqueue vq;
size_t vhost_hlen;
size_t sock_hlen;
/* vhost zerocopy support fields below: */
/* last used idx for outstanding DMA zerocopy buffers */
int upend_idx;
/* For TX, first used idx for DMA done zerocopy buffers
* For RX, number of batched heads
*/
int done_idx;
/* an array of userspace buffers info */
struct ubuf_info *ubuf_info;
/* Reference counting for outstanding ubufs.
* Protected by vq mutex. Writers must also take device mutex. */
struct vhost_net_ubuf_ref *ubufs;
struct ptr_ring *rx_ring;
struct vhost_net_buf rxq;
};
struct vhost_net {
struct vhost_dev dev;
struct vhost_net_virtqueue vqs[VHOST_NET_VQ_MAX];
struct vhost_poll poll[VHOST_NET_VQ_MAX];
/* Number of TX recently submitted.
* Protected by tx vq lock. */
unsigned tx_packets;
/* Number of times zerocopy TX recently failed.
* Protected by tx vq lock. */
unsigned tx_zcopy_err;
/* Flush in progress. Protected by tx vq lock. */
bool tx_flush;
};
static unsigned vhost_net_zcopy_mask __read_mostly;
static void *vhost_net_buf_get_ptr(struct vhost_net_buf *rxq)
{
if (rxq->tail != rxq->head)
return rxq->queue[rxq->head];
else
return NULL;
}
static int vhost_net_buf_get_size(struct vhost_net_buf *rxq)
{
return rxq->tail - rxq->head;
}
static int vhost_net_buf_is_empty(struct vhost_net_buf *rxq)
{
return rxq->tail == rxq->head;
}
static void *vhost_net_buf_consume(struct vhost_net_buf *rxq)
{
void *ret = vhost_net_buf_get_ptr(rxq);
++rxq->head;
return ret;
}
static int vhost_net_buf_produce(struct vhost_net_virtqueue *nvq)
{
struct vhost_net_buf *rxq = &nvq->rxq;
rxq->head = 0;
rxq->tail = ptr_ring_consume_batched(nvq->rx_ring, rxq->queue,
VHOST_NET_BATCH);
return rxq->tail;
}
static void vhost_net_buf_unproduce(struct vhost_net_virtqueue *nvq)
{
struct vhost_net_buf *rxq = &nvq->rxq;
if (nvq->rx_ring && !vhost_net_buf_is_empty(rxq)) {
ptr_ring_unconsume(nvq->rx_ring, rxq->queue + rxq->head,
vhost_net_buf_get_size(rxq),
tun_ptr_free);
rxq->head = rxq->tail = 0;
}
}
static int vhost_net_buf_peek_len(void *ptr)
{
if (tun_is_xdp_frame(ptr)) {
struct xdp_frame *xdpf = tun_ptr_to_xdp(ptr);
return xdpf->len;
}
return __skb_array_len_with_tag(ptr);
}
static int vhost_net_buf_peek(struct vhost_net_virtqueue *nvq)
{
struct vhost_net_buf *rxq = &nvq->rxq;
if (!vhost_net_buf_is_empty(rxq))
goto out;
if (!vhost_net_buf_produce(nvq))
return 0;
out:
return vhost_net_buf_peek_len(vhost_net_buf_get_ptr(rxq));
}
static void vhost_net_buf_init(struct vhost_net_buf *rxq)
{
rxq->head = rxq->tail = 0;
}
static void vhost_net_enable_zcopy(int vq)
{
vhost_net_zcopy_mask |= 0x1 << vq;
}
static struct vhost_net_ubuf_ref *
vhost_net_ubuf_alloc(struct vhost_virtqueue *vq, bool zcopy)
{
struct vhost_net_ubuf_ref *ubufs;
/* No zero copy backend? Nothing to count. */
if (!zcopy)
return NULL;
ubufs = kmalloc(sizeof(*ubufs), GFP_KERNEL);
if (!ubufs)
return ERR_PTR(-ENOMEM);
atomic_set(&ubufs->refcount, 1);
init_waitqueue_head(&ubufs->wait);
ubufs->vq = vq;
return ubufs;
}
static int vhost_net_ubuf_put(struct vhost_net_ubuf_ref *ubufs)
{
int r = atomic_sub_return(1, &ubufs->refcount);
if (unlikely(!r))
wake_up(&ubufs->wait);
return r;
}
static void vhost_net_ubuf_put_and_wait(struct vhost_net_ubuf_ref *ubufs)
{
vhost_net_ubuf_put(ubufs);
wait_event(ubufs->wait, !atomic_read(&ubufs->refcount));
}
static void vhost_net_ubuf_put_wait_and_free(struct vhost_net_ubuf_ref *ubufs)
{
vhost_net_ubuf_put_and_wait(ubufs);
kfree(ubufs);
}
static void vhost_net_clear_ubuf_info(struct vhost_net *n)
{
int i;
for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
kfree(n->vqs[i].ubuf_info);
n->vqs[i].ubuf_info = NULL;
}
}
static int vhost_net_set_ubuf_info(struct vhost_net *n)
{
bool zcopy;
int i;
for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
zcopy = vhost_net_zcopy_mask & (0x1 << i);
if (!zcopy)
continue;
n->vqs[i].ubuf_info =
kmalloc_array(UIO_MAXIOV,
sizeof(*n->vqs[i].ubuf_info),
GFP_KERNEL);
if (!n->vqs[i].ubuf_info)
goto err;
}
return 0;
err:
vhost_net_clear_ubuf_info(n);
return -ENOMEM;
}
static void vhost_net_vq_reset(struct vhost_net *n)
{
int i;
vhost_net_clear_ubuf_info(n);
for (i = 0; i < VHOST_NET_VQ_MAX; i++) {
n->vqs[i].done_idx = 0;
n->vqs[i].upend_idx = 0;
n->vqs[i].ubufs = NULL;
n->vqs[i].vhost_hlen = 0;
n->vqs[i].sock_hlen = 0;
vhost_net_buf_init(&n->vqs[i].rxq);
}
}
static void vhost_net_tx_packet(struct vhost_net *net)
{
++net->tx_packets;
if (net->tx_packets < 1024)
return;
net->tx_packets = 0;
net->tx_zcopy_err = 0;
}
static void vhost_net_tx_err(struct vhost_net *net)
{
++net->tx_zcopy_err;
}
static bool vhost_net_tx_select_zcopy(struct vhost_net *net)
{
/* TX flush waits for outstanding DMAs to be done.
* Don't start new DMAs.
*/
return !net->tx_flush &&
net->tx_packets / 64 >= net->tx_zcopy_err;
}
static bool vhost_sock_zcopy(struct socket *sock)
{
return unlikely(experimental_zcopytx) &&
sock_flag(sock->sk, SOCK_ZEROCOPY);
}
/* In case of DMA done not in order in lower device driver for some reason.
* upend_idx is used to track end of used idx, done_idx is used to track head
* of used idx. Once lower device DMA done contiguously, we will signal KVM
* guest used idx.
*/
static void vhost_zerocopy_signal_used(struct vhost_net *net,
struct vhost_virtqueue *vq)
{
struct vhost_net_virtqueue *nvq =
container_of(vq, struct vhost_net_virtqueue, vq);
int i, add;
int j = 0;
for (i = nvq->done_idx; i != nvq->upend_idx; i = (i + 1) % UIO_MAXIOV) {
if (vq->heads[i].len == VHOST_DMA_FAILED_LEN)
vhost_net_tx_err(net);
if (VHOST_DMA_IS_DONE(vq->heads[i].len)) {
vq->heads[i].len = VHOST_DMA_CLEAR_LEN;
++j;
} else
break;
}
while (j) {
add = min(UIO_MAXIOV - nvq->done_idx, j);
vhost_add_used_and_signal_n(vq->dev, vq,
&vq->heads[nvq->done_idx], add);
nvq->done_idx = (nvq->done_idx + add) % UIO_MAXIOV;
j -= add;
}
}
static void vhost_zerocopy_callback(struct ubuf_info *ubuf, bool success)
{
struct vhost_net_ubuf_ref *ubufs = ubuf->ctx;
struct vhost_virtqueue *vq = ubufs->vq;
int cnt;
rcu_read_lock_bh();
/* set len to mark this desc buffers done DMA */
vq->heads[ubuf->desc].len = success ?
VHOST_DMA_DONE_LEN : VHOST_DMA_FAILED_LEN;
cnt = vhost_net_ubuf_put(ubufs);
/*
* Trigger polling thread if guest stopped submitting new buffers:
* in this case, the refcount after decrement will eventually reach 1.
* We also trigger polling periodically after each 16 packets
* (the value 16 here is more or less arbitrary, it's tuned to trigger
* less than 10% of times).
*/
if (cnt <= 1 || !(cnt % 16))
vhost_poll_queue(&vq->poll);
rcu_read_unlock_bh();
}
static inline unsigned long busy_clock(void)
{
return local_clock() >> 10;
}
static bool vhost_can_busy_poll(unsigned long endtime)
{
return likely(!need_resched() && !time_after(busy_clock(), endtime) &&
!signal_pending(current));
}
static void vhost_net_disable_vq(struct vhost_net *n,
struct vhost_virtqueue *vq)
{
struct vhost_net_virtqueue *nvq =
container_of(vq, struct vhost_net_virtqueue, vq);
struct vhost_poll *poll = n->poll + (nvq - n->vqs);
if (!vq->private_data)
return;
vhost_poll_stop(poll);
}
static int vhost_net_enable_vq(struct vhost_net *n,
struct vhost_virtqueue *vq)
{
struct vhost_net_virtqueue *nvq =
container_of(vq, struct vhost_net_virtqueue, vq);
struct vhost_poll *poll = n->poll + (nvq - n->vqs);
struct socket *sock;
sock = vq->private_data;
if (!sock)
return 0;
return vhost_poll_start(poll, sock->file);
}
static void vhost_net_signal_used(struct vhost_net_virtqueue *nvq)
{
struct vhost_virtqueue *vq = &nvq->vq;
struct vhost_dev *dev = vq->dev;
if (!nvq->done_idx)
return;
vhost_add_used_and_signal_n(dev, vq, vq->heads, nvq->done_idx);
nvq->done_idx = 0;
}
static int vhost_net_tx_get_vq_desc(struct vhost_net *net,
struct vhost_net_virtqueue *nvq,
unsigned int *out_num, unsigned int *in_num,
bool *busyloop_intr)
{
struct vhost_virtqueue *vq = &nvq->vq;
unsigned long uninitialized_var(endtime);
int r = vhost_get_vq_desc(vq, vq->iov, ARRAY_SIZE(vq->iov),
out_num, in_num, NULL, NULL);
if (r == vq->num && vq->busyloop_timeout) {
if (!vhost_sock_zcopy(vq->private_data))
vhost_net_signal_used(nvq);
preempt_disable();
endtime = busy_clock() + vq->busyloop_timeout;
while (vhost_can_busy_poll(endtime)) {
if (vhost_has_work(vq->dev)) {
*busyloop_intr = true;
break;
}
if (!vhost_vq_avail_empty(vq->dev, vq))
break;
cpu_relax();
}
preempt_enable();
r = vhost_get_vq_desc(vq, vq->iov, ARRAY_SIZE(vq->iov),
out_num, in_num, NULL, NULL);
}
return r;
}
static bool vhost_exceeds_maxpend(struct vhost_net *net)
{
struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
struct vhost_virtqueue *vq = &nvq->vq;
return (nvq->upend_idx + UIO_MAXIOV - nvq->done_idx) % UIO_MAXIOV >
min_t(unsigned int, VHOST_MAX_PEND, vq->num >> 2);
}
static size_t init_iov_iter(struct vhost_virtqueue *vq, struct iov_iter *iter,
size_t hdr_size, int out)
{
/* Skip header. TODO: support TSO. */
size_t len = iov_length(vq->iov, out);
iov_iter_init(iter, WRITE, vq->iov, out, len);
iov_iter_advance(iter, hdr_size);
return iov_iter_count(iter);
}
static bool vhost_exceeds_weight(int pkts, int total_len)
{
return total_len >= VHOST_NET_WEIGHT ||
pkts >= VHOST_NET_PKT_WEIGHT;
}
static int get_tx_bufs(struct vhost_net *net,
struct vhost_net_virtqueue *nvq,
struct msghdr *msg,
unsigned int *out, unsigned int *in,
size_t *len, bool *busyloop_intr)
{
struct vhost_virtqueue *vq = &nvq->vq;
int ret;
ret = vhost_net_tx_get_vq_desc(net, nvq, out, in, busyloop_intr);
if (ret < 0 || ret == vq->num)
return ret;
if (*in) {
vq_err(vq, "Unexpected descriptor format for TX: out %d, int %d\n",
*out, *in);
return -EFAULT;
}
/* Sanity check */
*len = init_iov_iter(vq, &msg->msg_iter, nvq->vhost_hlen, *out);
if (*len == 0) {
vq_err(vq, "Unexpected header len for TX: %zd expected %zd\n",
*len, nvq->vhost_hlen);
return -EFAULT;
}
return ret;
}
static bool tx_can_batch(struct vhost_virtqueue *vq, size_t total_len)
{
return total_len < VHOST_NET_WEIGHT &&
!vhost_vq_avail_empty(vq->dev, vq);
}
static void handle_tx_copy(struct vhost_net *net, struct socket *sock)
{
struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
struct vhost_virtqueue *vq = &nvq->vq;
unsigned out, in;
int head;
struct msghdr msg = {
.msg_name = NULL,
.msg_namelen = 0,
.msg_control = NULL,
.msg_controllen = 0,
.msg_flags = MSG_DONTWAIT,
};
size_t len, total_len = 0;
int err;
int sent_pkts = 0;
for (;;) {
bool busyloop_intr = false;
head = get_tx_bufs(net, nvq, &msg, &out, &in, &len,
&busyloop_intr);
/* 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) {
if (unlikely(busyloop_intr)) {
vhost_poll_queue(&vq->poll);
} else if (unlikely(vhost_enable_notify(&net->dev,
vq))) {
vhost_disable_notify(&net->dev, vq);
continue;
}
break;
}
vq->heads[nvq->done_idx].id = cpu_to_vhost32(vq, head);
vq->heads[nvq->done_idx].len = 0;
total_len += len;
if (tx_can_batch(vq, total_len))
msg.msg_flags |= MSG_MORE;
else
msg.msg_flags &= ~MSG_MORE;
/* TODO: Check specific error and bomb out unless ENOBUFS? */
err = sock->ops->sendmsg(sock, &msg, len);
if (unlikely(err < 0)) {
vhost_discard_vq_desc(vq, 1);
vhost_net_enable_vq(net, vq);
break;
}
if (err != len)
pr_debug("Truncated TX packet: len %d != %zd\n",
err, len);
if (++nvq->done_idx >= VHOST_NET_BATCH)
vhost_net_signal_used(nvq);
if (vhost_exceeds_weight(++sent_pkts, total_len)) {
vhost_poll_queue(&vq->poll);
break;
}
}
vhost_net_signal_used(nvq);
}
static void handle_tx_zerocopy(struct vhost_net *net, struct socket *sock)
{
struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
struct vhost_virtqueue *vq = &nvq->vq;
unsigned out, in;
int head;
struct msghdr msg = {
.msg_name = NULL,
.msg_namelen = 0,
.msg_control = NULL,
.msg_controllen = 0,
.msg_flags = MSG_DONTWAIT,
};
size_t len, total_len = 0;
int err;
struct vhost_net_ubuf_ref *uninitialized_var(ubufs);
bool zcopy_used;
int sent_pkts = 0;
for (;;) {
bool busyloop_intr;
/* Release DMAs done buffers first */
vhost_zerocopy_signal_used(net, vq);
busyloop_intr = false;
head = get_tx_bufs(net, nvq, &msg, &out, &in, &len,
&busyloop_intr);
/* 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) {
if (unlikely(busyloop_intr)) {
vhost_poll_queue(&vq->poll);
} else if (unlikely(vhost_enable_notify(&net->dev, vq))) {
vhost_disable_notify(&net->dev, vq);
continue;
}
break;
}
zcopy_used = len >= VHOST_GOODCOPY_LEN
&& !vhost_exceeds_maxpend(net)
&& vhost_net_tx_select_zcopy(net);
/* use msg_control to pass vhost zerocopy ubuf info to skb */
if (zcopy_used) {
struct ubuf_info *ubuf;
ubuf = nvq->ubuf_info + nvq->upend_idx;
vq->heads[nvq->upend_idx].id = cpu_to_vhost32(vq, head);
vq->heads[nvq->upend_idx].len = VHOST_DMA_IN_PROGRESS;
ubuf->callback = vhost_zerocopy_callback;
ubuf->ctx = nvq->ubufs;
ubuf->desc = nvq->upend_idx;
refcount_set(&ubuf->refcnt, 1);
msg.msg_control = ubuf;
msg.msg_controllen = sizeof(ubuf);
ubufs = nvq->ubufs;
atomic_inc(&ubufs->refcount);
nvq->upend_idx = (nvq->upend_idx + 1) % UIO_MAXIOV;
} else {
msg.msg_control = NULL;
ubufs = NULL;
}
total_len += len;
if (tx_can_batch(vq, total_len) &&
likely(!vhost_exceeds_maxpend(net))) {
msg.msg_flags |= MSG_MORE;
} else {
msg.msg_flags &= ~MSG_MORE;
}
/* TODO: Check specific error and bomb out unless ENOBUFS? */
err = sock->ops->sendmsg(sock, &msg, len);
if (unlikely(err < 0)) {
if (zcopy_used) {
vhost_net_ubuf_put(ubufs);
nvq->upend_idx = ((unsigned)nvq->upend_idx - 1)
% UIO_MAXIOV;
}
vhost_discard_vq_desc(vq, 1);
vhost_net_enable_vq(net, vq);
break;
}
if (err != len)
pr_debug("Truncated TX packet: "
" len %d != %zd\n", err, len);
if (!zcopy_used)
vhost_add_used_and_signal(&net->dev, vq, head, 0);
else
vhost_zerocopy_signal_used(net, vq);
vhost_net_tx_packet(net);
if (unlikely(vhost_exceeds_weight(++sent_pkts, total_len))) {
vhost_poll_queue(&vq->poll);
break;
}
}
}
/* 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_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
struct vhost_virtqueue *vq = &nvq->vq;
struct socket *sock;
mutex_lock(&vq->mutex);
sock = vq->private_data;
if (!sock)
goto out;
if (!vq_iotlb_prefetch(vq))
goto out;
vhost_disable_notify(&net->dev, vq);
vhost_net_disable_vq(net, vq);
if (vhost_sock_zcopy(sock))
handle_tx_zerocopy(net, sock);
else
handle_tx_copy(net, sock);
out:
mutex_unlock(&vq->mutex);
}
static int peek_head_len(struct vhost_net_virtqueue *rvq, struct sock *sk)
{
struct sk_buff *head;
int len = 0;
unsigned long flags;
if (rvq->rx_ring)
return vhost_net_buf_peek(rvq);
spin_lock_irqsave(&sk->sk_receive_queue.lock, flags);
head = skb_peek(&sk->sk_receive_queue);
if (likely(head)) {
len = head->len;
if (skb_vlan_tag_present(head))
len += VLAN_HLEN;
}
spin_unlock_irqrestore(&sk->sk_receive_queue.lock, flags);
return len;
}
static int sk_has_rx_data(struct sock *sk)
{
struct socket *sock = sk->sk_socket;
if (sock->ops->peek_len)
return sock->ops->peek_len(sock);
return skb_queue_empty(&sk->sk_receive_queue);
}
static int vhost_net_rx_peek_head_len(struct vhost_net *net, struct sock *sk,
bool *busyloop_intr)
{
struct vhost_net_virtqueue *rnvq = &net->vqs[VHOST_NET_VQ_RX];
struct vhost_net_virtqueue *tnvq = &net->vqs[VHOST_NET_VQ_TX];
struct vhost_virtqueue *rvq = &rnvq->vq;
struct vhost_virtqueue *tvq = &tnvq->vq;
unsigned long uninitialized_var(endtime);
int len = peek_head_len(rnvq, sk);
if (!len && tvq->busyloop_timeout) {
/* Flush batched heads first */
vhost_net_signal_used(rnvq);
/* Both tx vq and rx socket were polled here */
mutex_lock_nested(&tvq->mutex, 1);
vhost_disable_notify(&net->dev, tvq);
preempt_disable();
endtime = busy_clock() + tvq->busyloop_timeout;
while (vhost_can_busy_poll(endtime)) {
if (vhost_has_work(&net->dev)) {
*busyloop_intr = true;
break;
}
if ((sk_has_rx_data(sk) &&
!vhost_vq_avail_empty(&net->dev, rvq)) ||
!vhost_vq_avail_empty(&net->dev, tvq))
break;
cpu_relax();
}
preempt_enable();
if (!vhost_vq_avail_empty(&net->dev, tvq)) {
vhost_poll_queue(&tvq->poll);
} else if (unlikely(vhost_enable_notify(&net->dev, tvq))) {
vhost_disable_notify(&net->dev, tvq);
vhost_poll_queue(&tvq->poll);
}
mutex_unlock(&tvq->mutex);
len = peek_head_len(rnvq, 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
* @quota - headcount quota, 1 for big buffer
* 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 quota)
{
unsigned int out, in;
int seg = 0;
int headcount = 0;
unsigned d;
int r, nlogs = 0;
/* len is always initialized before use since we are always called with
* datalen > 0.
*/
u32 uninitialized_var(len);
while (datalen > 0 && headcount < quota) {
if (unlikely(seg >= UIO_MAXIOV)) {
r = -ENOBUFS;
goto err;
}
r = vhost_get_vq_desc(vq, vq->iov + seg,
ARRAY_SIZE(vq->iov) - seg, &out,
&in, log, log_num);
if (unlikely(r < 0))
goto err;
d = r;
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 = cpu_to_vhost32(vq, d);
len = iov_length(vq->iov + seg, in);
heads[headcount].len = cpu_to_vhost32(vq, len);
datalen -= len;
++headcount;
seg += in;
}
heads[headcount - 1].len = cpu_to_vhost32(vq, len + datalen);
*iovcount = seg;
if (unlikely(log))
*log_num = nlogs;
/* Detect overrun */
if (unlikely(datalen > 0)) {
r = UIO_MAXIOV + 1;
goto err;
}
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(struct vhost_net *net)
{
struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_RX];
struct vhost_virtqueue *vq = &nvq->vq;
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_flags = MSG_DONTWAIT,
};
struct virtio_net_hdr hdr = {
.flags = 0,
.gso_type = VIRTIO_NET_HDR_GSO_NONE
};
size_t total_len = 0;
int err, mergeable;
s16 headcount;
size_t vhost_hlen, sock_hlen;
size_t vhost_len, sock_len;
bool busyloop_intr = false;
struct socket *sock;
struct iov_iter fixup;
__virtio16 num_buffers;
int recv_pkts = 0;
mutex_lock_nested(&vq->mutex, 0);
sock = vq->private_data;
if (!sock)
goto out;
if (!vq_iotlb_prefetch(vq))
goto out;
vhost_disable_notify(&net->dev, vq);
vhost_net_disable_vq(net, vq);
vhost_hlen = nvq->vhost_hlen;
sock_hlen = nvq->sock_hlen;
vq_log = unlikely(vhost_has_feature(vq, VHOST_F_LOG_ALL)) ?
vq->log : NULL;
mergeable = vhost_has_feature(vq, VIRTIO_NET_F_MRG_RXBUF);
while ((sock_len = vhost_net_rx_peek_head_len(net, sock->sk,
&busyloop_intr))) {
sock_len += sock_hlen;
vhost_len = sock_len + vhost_hlen;
headcount = get_rx_bufs(vq, vq->heads + nvq->done_idx,
vhost_len, &in, vq_log, &log,
likely(mergeable) ? UIO_MAXIOV : 1);
/* On error, stop handling until the next kick. */
if (unlikely(headcount < 0))
goto out;
/* OK, now we need to know about added descriptors. */
if (!headcount) {
if (unlikely(busyloop_intr)) {
vhost_poll_queue(&vq->poll);
} else if (unlikely(vhost_enable_notify(&net->dev, vq))) {
/* They have slipped one in as we were
* doing that: check again. */
vhost_disable_notify(&net->dev, vq);
continue;
}
/* Nothing new? Wait for eventfd to tell us
* they refilled. */
goto out;
}
busyloop_intr = false;
if (nvq->rx_ring)
msg.msg_control = vhost_net_buf_consume(&nvq->rxq);
/* On overrun, truncate and discard */
if (unlikely(headcount > UIO_MAXIOV)) {
iov_iter_init(&msg.msg_iter, READ, vq->iov, 1, 1);
err = sock->ops->recvmsg(sock, &msg,
1, MSG_DONTWAIT | MSG_TRUNC);
pr_debug("Discarded rx packet: len %zd\n", sock_len);
continue;
}
/* We don't need to be notified again. */
iov_iter_init(&msg.msg_iter, READ, vq->iov, in, vhost_len);
fixup = msg.msg_iter;
if (unlikely((vhost_hlen))) {
/* We will supply the header ourselves
* TODO: support TSO.
*/
iov_iter_advance(&msg.msg_iter, vhost_hlen);
}
err = sock->ops->recvmsg(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;
}
/* Supply virtio_net_hdr if VHOST_NET_F_VIRTIO_NET_HDR */
if (unlikely(vhost_hlen)) {
if (copy_to_iter(&hdr, sizeof(hdr),
&fixup) != sizeof(hdr)) {
vq_err(vq, "Unable to write vnet_hdr "
"at addr %p\n", vq->iov->iov_base);
goto out;
}
} else {
/* Header came from socket; we'll need to patch
* ->num_buffers over if VIRTIO_NET_F_MRG_RXBUF
*/
iov_iter_advance(&fixup, sizeof(hdr));
}
/* TODO: Should check and handle checksum. */
num_buffers = cpu_to_vhost16(vq, headcount);
if (likely(mergeable) &&
copy_to_iter(&num_buffers, sizeof num_buffers,
&fixup) != sizeof num_buffers) {
vq_err(vq, "Failed num_buffers write");
vhost_discard_vq_desc(vq, headcount);
goto out;
}
nvq->done_idx += headcount;
if (nvq->done_idx > VHOST_NET_BATCH)
vhost_net_signal_used(nvq);
if (unlikely(vq_log))
vhost_log_write(vq, vq_log, log, vhost_len);
total_len += vhost_len;
if (unlikely(vhost_exceeds_weight(++recv_pkts, total_len))) {
vhost_poll_queue(&vq->poll);
goto out;
}
}
if (unlikely(busyloop_intr))
vhost_poll_queue(&vq->poll);
else
vhost_net_enable_vq(net, vq);
out:
vhost_net_signal_used(nvq);
mutex_unlock(&vq->mutex);
}
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;
struct vhost_dev *dev;
struct vhost_virtqueue **vqs;
void **queue;
int i;
n = kvmalloc(sizeof *n, GFP_KERNEL | __GFP_RETRY_MAYFAIL);
if (!n)
return -ENOMEM;
vqs = kmalloc_array(VHOST_NET_VQ_MAX, sizeof(*vqs), GFP_KERNEL);
if (!vqs) {
kvfree(n);
return -ENOMEM;
}
queue = kmalloc_array(VHOST_NET_BATCH, sizeof(void *),
GFP_KERNEL);
if (!queue) {
kfree(vqs);
kvfree(n);
return -ENOMEM;
}
n->vqs[VHOST_NET_VQ_RX].rxq.queue = queue;
dev = &n->dev;
vqs[VHOST_NET_VQ_TX] = &n->vqs[VHOST_NET_VQ_TX].vq;
vqs[VHOST_NET_VQ_RX] = &n->vqs[VHOST_NET_VQ_RX].vq;
n->vqs[VHOST_NET_VQ_TX].vq.handle_kick = handle_tx_kick;
n->vqs[VHOST_NET_VQ_RX].vq.handle_kick = handle_rx_kick;
for (i = 0; i < VHOST_NET_VQ_MAX; i++) {
n->vqs[i].ubufs = NULL;
n->vqs[i].ubuf_info = NULL;
n->vqs[i].upend_idx = 0;
n->vqs[i].done_idx = 0;
n->vqs[i].vhost_hlen = 0;
n->vqs[i].sock_hlen = 0;
n->vqs[i].rx_ring = NULL;
vhost_net_buf_init(&n->vqs[i].rxq);
}
vhost_dev_init(dev, vqs, VHOST_NET_VQ_MAX);
vhost_poll_init(n->poll + VHOST_NET_VQ_TX, handle_tx_net, EPOLLOUT, dev);
vhost_poll_init(n->poll + VHOST_NET_VQ_RX, handle_rx_net, EPOLLIN, dev);
f->private_data = n;
return 0;
}
static struct socket *vhost_net_stop_vq(struct vhost_net *n,
struct vhost_virtqueue *vq)
{
struct socket *sock;
struct vhost_net_virtqueue *nvq =
container_of(vq, struct vhost_net_virtqueue, vq);
mutex_lock(&vq->mutex);
sock = vq->private_data;
vhost_net_disable_vq(n, vq);
vq->private_data = NULL;
vhost_net_buf_unproduce(nvq);
nvq->rx_ring = 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].vq);
*rx_sock = vhost_net_stop_vq(n, &n->vqs[VHOST_NET_VQ_RX].vq);
}
static void vhost_net_flush_vq(struct vhost_net *n, int index)
{
vhost_poll_flush(n->poll + index);
vhost_poll_flush(&n->vqs[index].vq.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);
if (n->vqs[VHOST_NET_VQ_TX].ubufs) {
mutex_lock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
n->tx_flush = true;
mutex_unlock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
/* Wait for all lower device DMAs done. */
vhost_net_ubuf_put_and_wait(n->vqs[VHOST_NET_VQ_TX].ubufs);
mutex_lock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
n->tx_flush = false;
atomic_set(&n->vqs[VHOST_NET_VQ_TX].ubufs->refcount, 1);
mutex_unlock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
}
}
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_stop(&n->dev);
vhost_dev_cleanup(&n->dev);
vhost_net_vq_reset(n);
if (tx_sock)
sockfd_put(tx_sock);
if (rx_sock)
sockfd_put(rx_sock);
/* Make sure no callbacks are outstanding */
synchronize_rcu_bh();
/* We do an extra flush before freeing memory,
* since jobs can re-queue themselves. */
vhost_net_flush(n);
kfree(n->vqs[VHOST_NET_VQ_RX].rxq.queue);
kfree(n->dev.vqs);
kvfree(n);
return 0;
}
static struct socket *get_raw_socket(int fd)
{
struct {
struct sockaddr_ll sa;
char buf[MAX_ADDR_LEN];
} uaddr;
int 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, 0);
if (r < 0)
goto err;
if (uaddr.sa.sll_family != AF_PACKET) {
r = -EPFNOSUPPORT;
goto err;
}
return sock;
err:
sockfd_put(sock);
return ERR_PTR(r);
}
static struct ptr_ring *get_tap_ptr_ring(int fd)
{
struct ptr_ring *ring;
struct file *file = fget(fd);
if (!file)
return NULL;
ring = tun_get_tx_ring(file);
if (!IS_ERR(ring))
goto out;
ring = tap_get_ptr_ring(file);
if (!IS_ERR(ring))
goto out;
ring = NULL;
out:
fput(file);
return ring;
}
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 = tap_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;
struct vhost_net_virtqueue *nvq;
struct vhost_net_ubuf_ref *ubufs, *oldubufs = NULL;
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].vq;
nvq = &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 = vq->private_data;
if (sock != oldsock) {
ubufs = vhost_net_ubuf_alloc(vq,
sock && vhost_sock_zcopy(sock));
if (IS_ERR(ubufs)) {
r = PTR_ERR(ubufs);
goto err_ubufs;
}
vhost_net_disable_vq(n, vq);
vq->private_data = sock;
vhost_net_buf_unproduce(nvq);
r = vhost_vq_init_access(vq);
if (r)
goto err_used;
r = vhost_net_enable_vq(n, vq);
if (r)
goto err_used;
if (index == VHOST_NET_VQ_RX)
nvq->rx_ring = get_tap_ptr_ring(fd);
oldubufs = nvq->ubufs;
nvq->ubufs = ubufs;
n->tx_packets = 0;
n->tx_zcopy_err = 0;
n->tx_flush = false;
}
mutex_unlock(&vq->mutex);
if (oldubufs) {
vhost_net_ubuf_put_wait_and_free(oldubufs);
mutex_lock(&vq->mutex);
vhost_zerocopy_signal_used(n, vq);
mutex_unlock(&vq->mutex);
}
if (oldsock) {
vhost_net_flush_vq(n, index);
sockfd_put(oldsock);
}
mutex_unlock(&n->dev.mutex);
return 0;
err_used:
vq->private_data = oldsock;
vhost_net_enable_vq(n, vq);
if (ubufs)
vhost_net_ubuf_put_wait_and_free(ubufs);
err_ubufs:
if (sock)
sockfd_put(sock);
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;
struct vhost_umem *umem;
mutex_lock(&n->dev.mutex);
err = vhost_dev_check_owner(&n->dev);
if (err)
goto done;
umem = vhost_dev_reset_owner_prepare();
if (!umem) {
err = -ENOMEM;
goto done;
}
vhost_net_stop(n, &tx_sock, &rx_sock);
vhost_net_flush(n);
vhost_dev_stop(&n->dev);
vhost_dev_reset_owner(&n->dev, umem);
vhost_net_vq_reset(n);
done:
mutex_unlock(&n->dev.mutex);
if (tx_sock)
sockfd_put(tx_sock);
if (rx_sock)
sockfd_put(rx_sock);
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 & ((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;
}
static long vhost_net_set_owner(struct vhost_net *n)
{
int r;
mutex_lock(&n->dev.mutex);
if (vhost_dev_has_owner(&n->dev)) {
r = -EBUSY;
goto out;
}
r = vhost_net_set_ubuf_info(n);
if (r)
goto out;
r = vhost_dev_set_owner(&n->dev);
if (r)
vhost_net_clear_ubuf_info(n);
vhost_net_flush(n);
out:
mutex_unlock(&n->dev.mutex);
return r;
}
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_NET_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_NET_FEATURES)
return -EOPNOTSUPP;
return vhost_net_set_features(n, features);
case VHOST_RESET_OWNER:
return vhost_net_reset_owner(n);
case VHOST_SET_OWNER:
return vhost_net_set_owner(n);
default:
mutex_lock(&n->dev.mutex);
r = vhost_dev_ioctl(&n->dev, ioctl, argp);
if (r == -ENOIOCTLCMD)
r = vhost_vring_ioctl(&n->dev, ioctl, argp);
else
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 ssize_t vhost_net_chr_read_iter(struct kiocb *iocb, struct iov_iter *to)
{
struct file *file = iocb->ki_filp;
struct vhost_net *n = file->private_data;
struct vhost_dev *dev = &n->dev;
int noblock = file->f_flags & O_NONBLOCK;
return vhost_chr_read_iter(dev, to, noblock);
}
static ssize_t vhost_net_chr_write_iter(struct kiocb *iocb,
struct iov_iter *from)
{
struct file *file = iocb->ki_filp;
struct vhost_net *n = file->private_data;
struct vhost_dev *dev = &n->dev;
return vhost_chr_write_iter(dev, from);
}
static __poll_t vhost_net_chr_poll(struct file *file, poll_table *wait)
{
struct vhost_net *n = file->private_data;
struct vhost_dev *dev = &n->dev;
return vhost_chr_poll(file, dev, wait);
}
static const struct file_operations vhost_net_fops = {
.owner = THIS_MODULE,
.release = vhost_net_release,
.read_iter = vhost_net_chr_read_iter,
.write_iter = vhost_net_chr_write_iter,
.poll = vhost_net_chr_poll,
.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 = {
.minor = VHOST_NET_MINOR,
.name = "vhost-net",
.fops = &vhost_net_fops,
};
static int vhost_net_init(void)
{
if (experimental_zcopytx)
vhost_net_enable_zcopy(VHOST_NET_VQ_TX);
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");
MODULE_ALIAS_MISCDEV(VHOST_NET_MINOR);
MODULE_ALIAS("devname:vhost-net");
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