9c3f8160ef2413540210b15aa1f37300e0261409
[muen/linux.git] / drivers / vhost / net.c
1 /* Copyright (C) 2009 Red Hat, Inc.
2  * Author: Michael S. Tsirkin <mst@redhat.com>
3  *
4  * This work is licensed under the terms of the GNU GPL, version 2.
5  *
6  * virtio-net server in host kernel.
7  */
8
9 #include <linux/compat.h>
10 #include <linux/eventfd.h>
11 #include <linux/vhost.h>
12 #include <linux/virtio_net.h>
13 #include <linux/miscdevice.h>
14 #include <linux/module.h>
15 #include <linux/moduleparam.h>
16 #include <linux/mutex.h>
17 #include <linux/workqueue.h>
18 #include <linux/file.h>
19 #include <linux/slab.h>
20 #include <linux/sched/clock.h>
21 #include <linux/sched/signal.h>
22 #include <linux/vmalloc.h>
23
24 #include <linux/net.h>
25 #include <linux/if_packet.h>
26 #include <linux/if_arp.h>
27 #include <linux/if_tun.h>
28 #include <linux/if_macvlan.h>
29 #include <linux/if_tap.h>
30 #include <linux/if_vlan.h>
31 #include <linux/skb_array.h>
32 #include <linux/skbuff.h>
33
34 #include <net/sock.h>
35
36 #include "vhost.h"
37
38 static int experimental_zcopytx = 1;
39 module_param(experimental_zcopytx, int, 0444);
40 MODULE_PARM_DESC(experimental_zcopytx, "Enable Zero Copy TX;"
41                                        " 1 -Enable; 0 - Disable");
42
43 /* Max number of bytes transferred before requeueing the job.
44  * Using this limit prevents one virtqueue from starving others. */
45 #define VHOST_NET_WEIGHT 0x80000
46
47 /* MAX number of TX used buffers for outstanding zerocopy */
48 #define VHOST_MAX_PEND 128
49 #define VHOST_GOODCOPY_LEN 256
50
51 /*
52  * For transmit, used buffer len is unused; we override it to track buffer
53  * status internally; used for zerocopy tx only.
54  */
55 /* Lower device DMA failed */
56 #define VHOST_DMA_FAILED_LEN    ((__force __virtio32)3)
57 /* Lower device DMA done */
58 #define VHOST_DMA_DONE_LEN      ((__force __virtio32)2)
59 /* Lower device DMA in progress */
60 #define VHOST_DMA_IN_PROGRESS   ((__force __virtio32)1)
61 /* Buffer unused */
62 #define VHOST_DMA_CLEAR_LEN     ((__force __virtio32)0)
63
64 #define VHOST_DMA_IS_DONE(len) ((__force u32)(len) >= (__force u32)VHOST_DMA_DONE_LEN)
65
66 enum {
67         VHOST_NET_FEATURES = VHOST_FEATURES |
68                          (1ULL << VHOST_NET_F_VIRTIO_NET_HDR) |
69                          (1ULL << VIRTIO_NET_F_MRG_RXBUF) |
70                          (1ULL << VIRTIO_F_IOMMU_PLATFORM)
71 };
72
73 enum {
74         VHOST_NET_VQ_RX = 0,
75         VHOST_NET_VQ_TX = 1,
76         VHOST_NET_VQ_MAX = 2,
77 };
78
79 struct vhost_net_ubuf_ref {
80         /* refcount follows semantics similar to kref:
81          *  0: object is released
82          *  1: no outstanding ubufs
83          * >1: outstanding ubufs
84          */
85         atomic_t refcount;
86         wait_queue_head_t wait;
87         struct vhost_virtqueue *vq;
88 };
89
90 #define VHOST_RX_BATCH 64
91 struct vhost_net_buf {
92         void **queue;
93         int tail;
94         int head;
95 };
96
97 struct vhost_net_virtqueue {
98         struct vhost_virtqueue vq;
99         size_t vhost_hlen;
100         size_t sock_hlen;
101         /* vhost zerocopy support fields below: */
102         /* last used idx for outstanding DMA zerocopy buffers */
103         int upend_idx;
104         /* first used idx for DMA done zerocopy buffers */
105         int done_idx;
106         /* an array of userspace buffers info */
107         struct ubuf_info *ubuf_info;
108         /* Reference counting for outstanding ubufs.
109          * Protected by vq mutex. Writers must also take device mutex. */
110         struct vhost_net_ubuf_ref *ubufs;
111         struct ptr_ring *rx_ring;
112         struct vhost_net_buf rxq;
113 };
114
115 struct vhost_net {
116         struct vhost_dev dev;
117         struct vhost_net_virtqueue vqs[VHOST_NET_VQ_MAX];
118         struct vhost_poll poll[VHOST_NET_VQ_MAX];
119         /* Number of TX recently submitted.
120          * Protected by tx vq lock. */
121         unsigned tx_packets;
122         /* Number of times zerocopy TX recently failed.
123          * Protected by tx vq lock. */
124         unsigned tx_zcopy_err;
125         /* Flush in progress. Protected by tx vq lock. */
126         bool tx_flush;
127 };
128
129 static unsigned vhost_net_zcopy_mask __read_mostly;
130
131 static void *vhost_net_buf_get_ptr(struct vhost_net_buf *rxq)
132 {
133         if (rxq->tail != rxq->head)
134                 return rxq->queue[rxq->head];
135         else
136                 return NULL;
137 }
138
139 static int vhost_net_buf_get_size(struct vhost_net_buf *rxq)
140 {
141         return rxq->tail - rxq->head;
142 }
143
144 static int vhost_net_buf_is_empty(struct vhost_net_buf *rxq)
145 {
146         return rxq->tail == rxq->head;
147 }
148
149 static void *vhost_net_buf_consume(struct vhost_net_buf *rxq)
150 {
151         void *ret = vhost_net_buf_get_ptr(rxq);
152         ++rxq->head;
153         return ret;
154 }
155
156 static int vhost_net_buf_produce(struct vhost_net_virtqueue *nvq)
157 {
158         struct vhost_net_buf *rxq = &nvq->rxq;
159
160         rxq->head = 0;
161         rxq->tail = ptr_ring_consume_batched(nvq->rx_ring, rxq->queue,
162                                               VHOST_RX_BATCH);
163         return rxq->tail;
164 }
165
166 static void vhost_net_buf_unproduce(struct vhost_net_virtqueue *nvq)
167 {
168         struct vhost_net_buf *rxq = &nvq->rxq;
169
170         if (nvq->rx_ring && !vhost_net_buf_is_empty(rxq)) {
171                 ptr_ring_unconsume(nvq->rx_ring, rxq->queue + rxq->head,
172                                    vhost_net_buf_get_size(rxq),
173                                    __skb_array_destroy_skb);
174                 rxq->head = rxq->tail = 0;
175         }
176 }
177
178 static int vhost_net_buf_peek_len(void *ptr)
179 {
180         if (tun_is_xdp_buff(ptr)) {
181                 struct xdp_buff *xdp = tun_ptr_to_xdp(ptr);
182
183                 return xdp->data_end - xdp->data;
184         }
185
186         return __skb_array_len_with_tag(ptr);
187 }
188
189 static int vhost_net_buf_peek(struct vhost_net_virtqueue *nvq)
190 {
191         struct vhost_net_buf *rxq = &nvq->rxq;
192
193         if (!vhost_net_buf_is_empty(rxq))
194                 goto out;
195
196         if (!vhost_net_buf_produce(nvq))
197                 return 0;
198
199 out:
200         return vhost_net_buf_peek_len(vhost_net_buf_get_ptr(rxq));
201 }
202
203 static void vhost_net_buf_init(struct vhost_net_buf *rxq)
204 {
205         rxq->head = rxq->tail = 0;
206 }
207
208 static void vhost_net_enable_zcopy(int vq)
209 {
210         vhost_net_zcopy_mask |= 0x1 << vq;
211 }
212
213 static struct vhost_net_ubuf_ref *
214 vhost_net_ubuf_alloc(struct vhost_virtqueue *vq, bool zcopy)
215 {
216         struct vhost_net_ubuf_ref *ubufs;
217         /* No zero copy backend? Nothing to count. */
218         if (!zcopy)
219                 return NULL;
220         ubufs = kmalloc(sizeof(*ubufs), GFP_KERNEL);
221         if (!ubufs)
222                 return ERR_PTR(-ENOMEM);
223         atomic_set(&ubufs->refcount, 1);
224         init_waitqueue_head(&ubufs->wait);
225         ubufs->vq = vq;
226         return ubufs;
227 }
228
229 static int vhost_net_ubuf_put(struct vhost_net_ubuf_ref *ubufs)
230 {
231         int r = atomic_sub_return(1, &ubufs->refcount);
232         if (unlikely(!r))
233                 wake_up(&ubufs->wait);
234         return r;
235 }
236
237 static void vhost_net_ubuf_put_and_wait(struct vhost_net_ubuf_ref *ubufs)
238 {
239         vhost_net_ubuf_put(ubufs);
240         wait_event(ubufs->wait, !atomic_read(&ubufs->refcount));
241 }
242
243 static void vhost_net_ubuf_put_wait_and_free(struct vhost_net_ubuf_ref *ubufs)
244 {
245         vhost_net_ubuf_put_and_wait(ubufs);
246         kfree(ubufs);
247 }
248
249 static void vhost_net_clear_ubuf_info(struct vhost_net *n)
250 {
251         int i;
252
253         for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
254                 kfree(n->vqs[i].ubuf_info);
255                 n->vqs[i].ubuf_info = NULL;
256         }
257 }
258
259 static int vhost_net_set_ubuf_info(struct vhost_net *n)
260 {
261         bool zcopy;
262         int i;
263
264         for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
265                 zcopy = vhost_net_zcopy_mask & (0x1 << i);
266                 if (!zcopy)
267                         continue;
268                 n->vqs[i].ubuf_info = kmalloc(sizeof(*n->vqs[i].ubuf_info) *
269                                               UIO_MAXIOV, GFP_KERNEL);
270                 if  (!n->vqs[i].ubuf_info)
271                         goto err;
272         }
273         return 0;
274
275 err:
276         vhost_net_clear_ubuf_info(n);
277         return -ENOMEM;
278 }
279
280 static void vhost_net_vq_reset(struct vhost_net *n)
281 {
282         int i;
283
284         vhost_net_clear_ubuf_info(n);
285
286         for (i = 0; i < VHOST_NET_VQ_MAX; i++) {
287                 n->vqs[i].done_idx = 0;
288                 n->vqs[i].upend_idx = 0;
289                 n->vqs[i].ubufs = NULL;
290                 n->vqs[i].vhost_hlen = 0;
291                 n->vqs[i].sock_hlen = 0;
292                 vhost_net_buf_init(&n->vqs[i].rxq);
293         }
294
295 }
296
297 static void vhost_net_tx_packet(struct vhost_net *net)
298 {
299         ++net->tx_packets;
300         if (net->tx_packets < 1024)
301                 return;
302         net->tx_packets = 0;
303         net->tx_zcopy_err = 0;
304 }
305
306 static void vhost_net_tx_err(struct vhost_net *net)
307 {
308         ++net->tx_zcopy_err;
309 }
310
311 static bool vhost_net_tx_select_zcopy(struct vhost_net *net)
312 {
313         /* TX flush waits for outstanding DMAs to be done.
314          * Don't start new DMAs.
315          */
316         return !net->tx_flush &&
317                 net->tx_packets / 64 >= net->tx_zcopy_err;
318 }
319
320 static bool vhost_sock_zcopy(struct socket *sock)
321 {
322         return unlikely(experimental_zcopytx) &&
323                 sock_flag(sock->sk, SOCK_ZEROCOPY);
324 }
325
326 /* In case of DMA done not in order in lower device driver for some reason.
327  * upend_idx is used to track end of used idx, done_idx is used to track head
328  * of used idx. Once lower device DMA done contiguously, we will signal KVM
329  * guest used idx.
330  */
331 static void vhost_zerocopy_signal_used(struct vhost_net *net,
332                                        struct vhost_virtqueue *vq)
333 {
334         struct vhost_net_virtqueue *nvq =
335                 container_of(vq, struct vhost_net_virtqueue, vq);
336         int i, add;
337         int j = 0;
338
339         for (i = nvq->done_idx; i != nvq->upend_idx; i = (i + 1) % UIO_MAXIOV) {
340                 if (vq->heads[i].len == VHOST_DMA_FAILED_LEN)
341                         vhost_net_tx_err(net);
342                 if (VHOST_DMA_IS_DONE(vq->heads[i].len)) {
343                         vq->heads[i].len = VHOST_DMA_CLEAR_LEN;
344                         ++j;
345                 } else
346                         break;
347         }
348         while (j) {
349                 add = min(UIO_MAXIOV - nvq->done_idx, j);
350                 vhost_add_used_and_signal_n(vq->dev, vq,
351                                             &vq->heads[nvq->done_idx], add);
352                 nvq->done_idx = (nvq->done_idx + add) % UIO_MAXIOV;
353                 j -= add;
354         }
355 }
356
357 static void vhost_zerocopy_callback(struct ubuf_info *ubuf, bool success)
358 {
359         struct vhost_net_ubuf_ref *ubufs = ubuf->ctx;
360         struct vhost_virtqueue *vq = ubufs->vq;
361         int cnt;
362
363         rcu_read_lock_bh();
364
365         /* set len to mark this desc buffers done DMA */
366         vq->heads[ubuf->desc].len = success ?
367                 VHOST_DMA_DONE_LEN : VHOST_DMA_FAILED_LEN;
368         cnt = vhost_net_ubuf_put(ubufs);
369
370         /*
371          * Trigger polling thread if guest stopped submitting new buffers:
372          * in this case, the refcount after decrement will eventually reach 1.
373          * We also trigger polling periodically after each 16 packets
374          * (the value 16 here is more or less arbitrary, it's tuned to trigger
375          * less than 10% of times).
376          */
377         if (cnt <= 1 || !(cnt % 16))
378                 vhost_poll_queue(&vq->poll);
379
380         rcu_read_unlock_bh();
381 }
382
383 static inline unsigned long busy_clock(void)
384 {
385         return local_clock() >> 10;
386 }
387
388 static bool vhost_can_busy_poll(struct vhost_dev *dev,
389                                 unsigned long endtime)
390 {
391         return likely(!need_resched()) &&
392                likely(!time_after(busy_clock(), endtime)) &&
393                likely(!signal_pending(current)) &&
394                !vhost_has_work(dev);
395 }
396
397 static void vhost_net_disable_vq(struct vhost_net *n,
398                                  struct vhost_virtqueue *vq)
399 {
400         struct vhost_net_virtqueue *nvq =
401                 container_of(vq, struct vhost_net_virtqueue, vq);
402         struct vhost_poll *poll = n->poll + (nvq - n->vqs);
403         if (!vq->private_data)
404                 return;
405         vhost_poll_stop(poll);
406 }
407
408 static int vhost_net_enable_vq(struct vhost_net *n,
409                                 struct vhost_virtqueue *vq)
410 {
411         struct vhost_net_virtqueue *nvq =
412                 container_of(vq, struct vhost_net_virtqueue, vq);
413         struct vhost_poll *poll = n->poll + (nvq - n->vqs);
414         struct socket *sock;
415
416         sock = vq->private_data;
417         if (!sock)
418                 return 0;
419
420         return vhost_poll_start(poll, sock->file);
421 }
422
423 static int vhost_net_tx_get_vq_desc(struct vhost_net *net,
424                                     struct vhost_virtqueue *vq,
425                                     struct iovec iov[], unsigned int iov_size,
426                                     unsigned int *out_num, unsigned int *in_num)
427 {
428         unsigned long uninitialized_var(endtime);
429         int r = vhost_get_vq_desc(vq, vq->iov, ARRAY_SIZE(vq->iov),
430                                   out_num, in_num, NULL, NULL);
431
432         if (r == vq->num && vq->busyloop_timeout) {
433                 preempt_disable();
434                 endtime = busy_clock() + vq->busyloop_timeout;
435                 while (vhost_can_busy_poll(vq->dev, endtime) &&
436                        vhost_vq_avail_empty(vq->dev, vq))
437                         cpu_relax();
438                 preempt_enable();
439                 r = vhost_get_vq_desc(vq, vq->iov, ARRAY_SIZE(vq->iov),
440                                       out_num, in_num, NULL, NULL);
441         }
442
443         return r;
444 }
445
446 static bool vhost_exceeds_maxpend(struct vhost_net *net)
447 {
448         struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
449         struct vhost_virtqueue *vq = &nvq->vq;
450
451         return (nvq->upend_idx + UIO_MAXIOV - nvq->done_idx) % UIO_MAXIOV >
452                min_t(unsigned int, VHOST_MAX_PEND, vq->num >> 2);
453 }
454
455 /* Expects to be always run from workqueue - which acts as
456  * read-size critical section for our kind of RCU. */
457 static void handle_tx(struct vhost_net *net)
458 {
459         struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
460         struct vhost_virtqueue *vq = &nvq->vq;
461         unsigned out, in;
462         int head;
463         struct msghdr msg = {
464                 .msg_name = NULL,
465                 .msg_namelen = 0,
466                 .msg_control = NULL,
467                 .msg_controllen = 0,
468                 .msg_flags = MSG_DONTWAIT,
469         };
470         size_t len, total_len = 0;
471         int err;
472         size_t hdr_size;
473         struct socket *sock;
474         struct vhost_net_ubuf_ref *uninitialized_var(ubufs);
475         bool zcopy, zcopy_used;
476
477         mutex_lock(&vq->mutex);
478         sock = vq->private_data;
479         if (!sock)
480                 goto out;
481
482         if (!vq_iotlb_prefetch(vq))
483                 goto out;
484
485         vhost_disable_notify(&net->dev, vq);
486         vhost_net_disable_vq(net, vq);
487
488         hdr_size = nvq->vhost_hlen;
489         zcopy = nvq->ubufs;
490
491         for (;;) {
492                 /* Release DMAs done buffers first */
493                 if (zcopy)
494                         vhost_zerocopy_signal_used(net, vq);
495
496
497                 head = vhost_net_tx_get_vq_desc(net, vq, vq->iov,
498                                                 ARRAY_SIZE(vq->iov),
499                                                 &out, &in);
500                 /* On error, stop handling until the next kick. */
501                 if (unlikely(head < 0))
502                         break;
503                 /* Nothing new?  Wait for eventfd to tell us they refilled. */
504                 if (head == vq->num) {
505                         if (unlikely(vhost_enable_notify(&net->dev, vq))) {
506                                 vhost_disable_notify(&net->dev, vq);
507                                 continue;
508                         }
509                         break;
510                 }
511                 if (in) {
512                         vq_err(vq, "Unexpected descriptor format for TX: "
513                                "out %d, int %d\n", out, in);
514                         break;
515                 }
516                 /* Skip header. TODO: support TSO. */
517                 len = iov_length(vq->iov, out);
518                 iov_iter_init(&msg.msg_iter, WRITE, vq->iov, out, len);
519                 iov_iter_advance(&msg.msg_iter, hdr_size);
520                 /* Sanity check */
521                 if (!msg_data_left(&msg)) {
522                         vq_err(vq, "Unexpected header len for TX: "
523                                "%zd expected %zd\n",
524                                len, hdr_size);
525                         break;
526                 }
527                 len = msg_data_left(&msg);
528
529                 zcopy_used = zcopy && len >= VHOST_GOODCOPY_LEN
530                                    && !vhost_exceeds_maxpend(net)
531                                    && vhost_net_tx_select_zcopy(net);
532
533                 /* use msg_control to pass vhost zerocopy ubuf info to skb */
534                 if (zcopy_used) {
535                         struct ubuf_info *ubuf;
536                         ubuf = nvq->ubuf_info + nvq->upend_idx;
537
538                         vq->heads[nvq->upend_idx].id = cpu_to_vhost32(vq, head);
539                         vq->heads[nvq->upend_idx].len = VHOST_DMA_IN_PROGRESS;
540                         ubuf->callback = vhost_zerocopy_callback;
541                         ubuf->ctx = nvq->ubufs;
542                         ubuf->desc = nvq->upend_idx;
543                         refcount_set(&ubuf->refcnt, 1);
544                         msg.msg_control = ubuf;
545                         msg.msg_controllen = sizeof(ubuf);
546                         ubufs = nvq->ubufs;
547                         atomic_inc(&ubufs->refcount);
548                         nvq->upend_idx = (nvq->upend_idx + 1) % UIO_MAXIOV;
549                 } else {
550                         msg.msg_control = NULL;
551                         ubufs = NULL;
552                 }
553
554                 total_len += len;
555                 if (total_len < VHOST_NET_WEIGHT &&
556                     !vhost_vq_avail_empty(&net->dev, vq) &&
557                     likely(!vhost_exceeds_maxpend(net))) {
558                         msg.msg_flags |= MSG_MORE;
559                 } else {
560                         msg.msg_flags &= ~MSG_MORE;
561                 }
562
563                 /* TODO: Check specific error and bomb out unless ENOBUFS? */
564                 err = sock->ops->sendmsg(sock, &msg, len);
565                 if (unlikely(err < 0)) {
566                         if (zcopy_used) {
567                                 vhost_net_ubuf_put(ubufs);
568                                 nvq->upend_idx = ((unsigned)nvq->upend_idx - 1)
569                                         % UIO_MAXIOV;
570                         }
571                         vhost_discard_vq_desc(vq, 1);
572                         vhost_net_enable_vq(net, vq);
573                         break;
574                 }
575                 if (err != len)
576                         pr_debug("Truncated TX packet: "
577                                  " len %d != %zd\n", err, len);
578                 if (!zcopy_used)
579                         vhost_add_used_and_signal(&net->dev, vq, head, 0);
580                 else
581                         vhost_zerocopy_signal_used(net, vq);
582                 vhost_net_tx_packet(net);
583                 if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
584                         vhost_poll_queue(&vq->poll);
585                         break;
586                 }
587         }
588 out:
589         mutex_unlock(&vq->mutex);
590 }
591
592 static int peek_head_len(struct vhost_net_virtqueue *rvq, struct sock *sk)
593 {
594         struct sk_buff *head;
595         int len = 0;
596         unsigned long flags;
597
598         if (rvq->rx_ring)
599                 return vhost_net_buf_peek(rvq);
600
601         spin_lock_irqsave(&sk->sk_receive_queue.lock, flags);
602         head = skb_peek(&sk->sk_receive_queue);
603         if (likely(head)) {
604                 len = head->len;
605                 if (skb_vlan_tag_present(head))
606                         len += VLAN_HLEN;
607         }
608
609         spin_unlock_irqrestore(&sk->sk_receive_queue.lock, flags);
610         return len;
611 }
612
613 static int sk_has_rx_data(struct sock *sk)
614 {
615         struct socket *sock = sk->sk_socket;
616
617         if (sock->ops->peek_len)
618                 return sock->ops->peek_len(sock);
619
620         return skb_queue_empty(&sk->sk_receive_queue);
621 }
622
623 static int vhost_net_rx_peek_head_len(struct vhost_net *net, struct sock *sk)
624 {
625         struct vhost_net_virtqueue *rvq = &net->vqs[VHOST_NET_VQ_RX];
626         struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
627         struct vhost_virtqueue *vq = &nvq->vq;
628         unsigned long uninitialized_var(endtime);
629         int len = peek_head_len(rvq, sk);
630
631         if (!len && vq->busyloop_timeout) {
632                 /* Both tx vq and rx socket were polled here */
633                 mutex_lock(&vq->mutex);
634                 vhost_disable_notify(&net->dev, vq);
635
636                 preempt_disable();
637                 endtime = busy_clock() + vq->busyloop_timeout;
638
639                 while (vhost_can_busy_poll(&net->dev, endtime) &&
640                        !sk_has_rx_data(sk) &&
641                        vhost_vq_avail_empty(&net->dev, vq))
642                         cpu_relax();
643
644                 preempt_enable();
645
646                 if (!vhost_vq_avail_empty(&net->dev, vq))
647                         vhost_poll_queue(&vq->poll);
648                 else if (unlikely(vhost_enable_notify(&net->dev, vq))) {
649                         vhost_disable_notify(&net->dev, vq);
650                         vhost_poll_queue(&vq->poll);
651                 }
652
653                 mutex_unlock(&vq->mutex);
654
655                 len = peek_head_len(rvq, sk);
656         }
657
658         return len;
659 }
660
661 /* This is a multi-buffer version of vhost_get_desc, that works if
662  *      vq has read descriptors only.
663  * @vq          - the relevant virtqueue
664  * @datalen     - data length we'll be reading
665  * @iovcount    - returned count of io vectors we fill
666  * @log         - vhost log
667  * @log_num     - log offset
668  * @quota       - headcount quota, 1 for big buffer
669  *      returns number of buffer heads allocated, negative on error
670  */
671 static int get_rx_bufs(struct vhost_virtqueue *vq,
672                        struct vring_used_elem *heads,
673                        int datalen,
674                        unsigned *iovcount,
675                        struct vhost_log *log,
676                        unsigned *log_num,
677                        unsigned int quota)
678 {
679         unsigned int out, in;
680         int seg = 0;
681         int headcount = 0;
682         unsigned d;
683         int r, nlogs = 0;
684         /* len is always initialized before use since we are always called with
685          * datalen > 0.
686          */
687         u32 uninitialized_var(len);
688
689         while (datalen > 0 && headcount < quota) {
690                 if (unlikely(seg >= UIO_MAXIOV)) {
691                         r = -ENOBUFS;
692                         goto err;
693                 }
694                 r = vhost_get_vq_desc(vq, vq->iov + seg,
695                                       ARRAY_SIZE(vq->iov) - seg, &out,
696                                       &in, log, log_num);
697                 if (unlikely(r < 0))
698                         goto err;
699
700                 d = r;
701                 if (d == vq->num) {
702                         r = 0;
703                         goto err;
704                 }
705                 if (unlikely(out || in <= 0)) {
706                         vq_err(vq, "unexpected descriptor format for RX: "
707                                 "out %d, in %d\n", out, in);
708                         r = -EINVAL;
709                         goto err;
710                 }
711                 if (unlikely(log)) {
712                         nlogs += *log_num;
713                         log += *log_num;
714                 }
715                 heads[headcount].id = cpu_to_vhost32(vq, d);
716                 len = iov_length(vq->iov + seg, in);
717                 heads[headcount].len = cpu_to_vhost32(vq, len);
718                 datalen -= len;
719                 ++headcount;
720                 seg += in;
721         }
722         heads[headcount - 1].len = cpu_to_vhost32(vq, len + datalen);
723         *iovcount = seg;
724         if (unlikely(log))
725                 *log_num = nlogs;
726
727         /* Detect overrun */
728         if (unlikely(datalen > 0)) {
729                 r = UIO_MAXIOV + 1;
730                 goto err;
731         }
732         return headcount;
733 err:
734         vhost_discard_vq_desc(vq, headcount);
735         return r;
736 }
737
738 /* Expects to be always run from workqueue - which acts as
739  * read-size critical section for our kind of RCU. */
740 static void handle_rx(struct vhost_net *net)
741 {
742         struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_RX];
743         struct vhost_virtqueue *vq = &nvq->vq;
744         unsigned uninitialized_var(in), log;
745         struct vhost_log *vq_log;
746         struct msghdr msg = {
747                 .msg_name = NULL,
748                 .msg_namelen = 0,
749                 .msg_control = NULL, /* FIXME: get and handle RX aux data. */
750                 .msg_controllen = 0,
751                 .msg_flags = MSG_DONTWAIT,
752         };
753         struct virtio_net_hdr hdr = {
754                 .flags = 0,
755                 .gso_type = VIRTIO_NET_HDR_GSO_NONE
756         };
757         size_t total_len = 0;
758         int err, mergeable;
759         s16 headcount, nheads = 0;
760         size_t vhost_hlen, sock_hlen;
761         size_t vhost_len, sock_len;
762         struct socket *sock;
763         struct iov_iter fixup;
764         __virtio16 num_buffers;
765
766         mutex_lock(&vq->mutex);
767         sock = vq->private_data;
768         if (!sock)
769                 goto out;
770
771         if (!vq_iotlb_prefetch(vq))
772                 goto out;
773
774         vhost_disable_notify(&net->dev, vq);
775         vhost_net_disable_vq(net, vq);
776
777         vhost_hlen = nvq->vhost_hlen;
778         sock_hlen = nvq->sock_hlen;
779
780         vq_log = unlikely(vhost_has_feature(vq, VHOST_F_LOG_ALL)) ?
781                 vq->log : NULL;
782         mergeable = vhost_has_feature(vq, VIRTIO_NET_F_MRG_RXBUF);
783
784         while ((sock_len = vhost_net_rx_peek_head_len(net, sock->sk))) {
785                 sock_len += sock_hlen;
786                 vhost_len = sock_len + vhost_hlen;
787                 headcount = get_rx_bufs(vq, vq->heads + nheads, vhost_len,
788                                         &in, vq_log, &log,
789                                         likely(mergeable) ? UIO_MAXIOV : 1);
790                 /* On error, stop handling until the next kick. */
791                 if (unlikely(headcount < 0))
792                         goto out;
793                 /* OK, now we need to know about added descriptors. */
794                 if (!headcount) {
795                         if (unlikely(vhost_enable_notify(&net->dev, vq))) {
796                                 /* They have slipped one in as we were
797                                  * doing that: check again. */
798                                 vhost_disable_notify(&net->dev, vq);
799                                 continue;
800                         }
801                         /* Nothing new?  Wait for eventfd to tell us
802                          * they refilled. */
803                         goto out;
804                 }
805                 if (nvq->rx_ring)
806                         msg.msg_control = vhost_net_buf_consume(&nvq->rxq);
807                 /* On overrun, truncate and discard */
808                 if (unlikely(headcount > UIO_MAXIOV)) {
809                         iov_iter_init(&msg.msg_iter, READ, vq->iov, 1, 1);
810                         err = sock->ops->recvmsg(sock, &msg,
811                                                  1, MSG_DONTWAIT | MSG_TRUNC);
812                         pr_debug("Discarded rx packet: len %zd\n", sock_len);
813                         continue;
814                 }
815                 /* We don't need to be notified again. */
816                 iov_iter_init(&msg.msg_iter, READ, vq->iov, in, vhost_len);
817                 fixup = msg.msg_iter;
818                 if (unlikely((vhost_hlen))) {
819                         /* We will supply the header ourselves
820                          * TODO: support TSO.
821                          */
822                         iov_iter_advance(&msg.msg_iter, vhost_hlen);
823                 }
824                 err = sock->ops->recvmsg(sock, &msg,
825                                          sock_len, MSG_DONTWAIT | MSG_TRUNC);
826                 /* Userspace might have consumed the packet meanwhile:
827                  * it's not supposed to do this usually, but might be hard
828                  * to prevent. Discard data we got (if any) and keep going. */
829                 if (unlikely(err != sock_len)) {
830                         pr_debug("Discarded rx packet: "
831                                  " len %d, expected %zd\n", err, sock_len);
832                         vhost_discard_vq_desc(vq, headcount);
833                         continue;
834                 }
835                 /* Supply virtio_net_hdr if VHOST_NET_F_VIRTIO_NET_HDR */
836                 if (unlikely(vhost_hlen)) {
837                         if (copy_to_iter(&hdr, sizeof(hdr),
838                                          &fixup) != sizeof(hdr)) {
839                                 vq_err(vq, "Unable to write vnet_hdr "
840                                        "at addr %p\n", vq->iov->iov_base);
841                                 goto out;
842                         }
843                 } else {
844                         /* Header came from socket; we'll need to patch
845                          * ->num_buffers over if VIRTIO_NET_F_MRG_RXBUF
846                          */
847                         iov_iter_advance(&fixup, sizeof(hdr));
848                 }
849                 /* TODO: Should check and handle checksum. */
850
851                 num_buffers = cpu_to_vhost16(vq, headcount);
852                 if (likely(mergeable) &&
853                     copy_to_iter(&num_buffers, sizeof num_buffers,
854                                  &fixup) != sizeof num_buffers) {
855                         vq_err(vq, "Failed num_buffers write");
856                         vhost_discard_vq_desc(vq, headcount);
857                         goto out;
858                 }
859                 nheads += headcount;
860                 if (nheads > VHOST_RX_BATCH) {
861                         vhost_add_used_and_signal_n(&net->dev, vq, vq->heads,
862                                                     nheads);
863                         nheads = 0;
864                 }
865                 if (unlikely(vq_log))
866                         vhost_log_write(vq, vq_log, log, vhost_len);
867                 total_len += vhost_len;
868                 if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
869                         vhost_poll_queue(&vq->poll);
870                         goto out;
871                 }
872         }
873         vhost_net_enable_vq(net, vq);
874 out:
875         if (nheads)
876                 vhost_add_used_and_signal_n(&net->dev, vq, vq->heads,
877                                             nheads);
878         mutex_unlock(&vq->mutex);
879 }
880
881 static void handle_tx_kick(struct vhost_work *work)
882 {
883         struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
884                                                   poll.work);
885         struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev);
886
887         handle_tx(net);
888 }
889
890 static void handle_rx_kick(struct vhost_work *work)
891 {
892         struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
893                                                   poll.work);
894         struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev);
895
896         handle_rx(net);
897 }
898
899 static void handle_tx_net(struct vhost_work *work)
900 {
901         struct vhost_net *net = container_of(work, struct vhost_net,
902                                              poll[VHOST_NET_VQ_TX].work);
903         handle_tx(net);
904 }
905
906 static void handle_rx_net(struct vhost_work *work)
907 {
908         struct vhost_net *net = container_of(work, struct vhost_net,
909                                              poll[VHOST_NET_VQ_RX].work);
910         handle_rx(net);
911 }
912
913 static int vhost_net_open(struct inode *inode, struct file *f)
914 {
915         struct vhost_net *n;
916         struct vhost_dev *dev;
917         struct vhost_virtqueue **vqs;
918         void **queue;
919         int i;
920
921         n = kvmalloc(sizeof *n, GFP_KERNEL | __GFP_RETRY_MAYFAIL);
922         if (!n)
923                 return -ENOMEM;
924         vqs = kmalloc(VHOST_NET_VQ_MAX * sizeof(*vqs), GFP_KERNEL);
925         if (!vqs) {
926                 kvfree(n);
927                 return -ENOMEM;
928         }
929
930         queue = kmalloc_array(VHOST_RX_BATCH, sizeof(void *),
931                               GFP_KERNEL);
932         if (!queue) {
933                 kfree(vqs);
934                 kvfree(n);
935                 return -ENOMEM;
936         }
937         n->vqs[VHOST_NET_VQ_RX].rxq.queue = queue;
938
939         dev = &n->dev;
940         vqs[VHOST_NET_VQ_TX] = &n->vqs[VHOST_NET_VQ_TX].vq;
941         vqs[VHOST_NET_VQ_RX] = &n->vqs[VHOST_NET_VQ_RX].vq;
942         n->vqs[VHOST_NET_VQ_TX].vq.handle_kick = handle_tx_kick;
943         n->vqs[VHOST_NET_VQ_RX].vq.handle_kick = handle_rx_kick;
944         for (i = 0; i < VHOST_NET_VQ_MAX; i++) {
945                 n->vqs[i].ubufs = NULL;
946                 n->vqs[i].ubuf_info = NULL;
947                 n->vqs[i].upend_idx = 0;
948                 n->vqs[i].done_idx = 0;
949                 n->vqs[i].vhost_hlen = 0;
950                 n->vqs[i].sock_hlen = 0;
951                 vhost_net_buf_init(&n->vqs[i].rxq);
952         }
953         vhost_dev_init(dev, vqs, VHOST_NET_VQ_MAX);
954
955         vhost_poll_init(n->poll + VHOST_NET_VQ_TX, handle_tx_net, POLLOUT, dev);
956         vhost_poll_init(n->poll + VHOST_NET_VQ_RX, handle_rx_net, POLLIN, dev);
957
958         f->private_data = n;
959
960         return 0;
961 }
962
963 static struct socket *vhost_net_stop_vq(struct vhost_net *n,
964                                         struct vhost_virtqueue *vq)
965 {
966         struct socket *sock;
967         struct vhost_net_virtqueue *nvq =
968                 container_of(vq, struct vhost_net_virtqueue, vq);
969
970         mutex_lock(&vq->mutex);
971         sock = vq->private_data;
972         vhost_net_disable_vq(n, vq);
973         vq->private_data = NULL;
974         vhost_net_buf_unproduce(nvq);
975         mutex_unlock(&vq->mutex);
976         return sock;
977 }
978
979 static void vhost_net_stop(struct vhost_net *n, struct socket **tx_sock,
980                            struct socket **rx_sock)
981 {
982         *tx_sock = vhost_net_stop_vq(n, &n->vqs[VHOST_NET_VQ_TX].vq);
983         *rx_sock = vhost_net_stop_vq(n, &n->vqs[VHOST_NET_VQ_RX].vq);
984 }
985
986 static void vhost_net_flush_vq(struct vhost_net *n, int index)
987 {
988         vhost_poll_flush(n->poll + index);
989         vhost_poll_flush(&n->vqs[index].vq.poll);
990 }
991
992 static void vhost_net_flush(struct vhost_net *n)
993 {
994         vhost_net_flush_vq(n, VHOST_NET_VQ_TX);
995         vhost_net_flush_vq(n, VHOST_NET_VQ_RX);
996         if (n->vqs[VHOST_NET_VQ_TX].ubufs) {
997                 mutex_lock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
998                 n->tx_flush = true;
999                 mutex_unlock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
1000                 /* Wait for all lower device DMAs done. */
1001                 vhost_net_ubuf_put_and_wait(n->vqs[VHOST_NET_VQ_TX].ubufs);
1002                 mutex_lock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
1003                 n->tx_flush = false;
1004                 atomic_set(&n->vqs[VHOST_NET_VQ_TX].ubufs->refcount, 1);
1005                 mutex_unlock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
1006         }
1007 }
1008
1009 static int vhost_net_release(struct inode *inode, struct file *f)
1010 {
1011         struct vhost_net *n = f->private_data;
1012         struct socket *tx_sock;
1013         struct socket *rx_sock;
1014
1015         vhost_net_stop(n, &tx_sock, &rx_sock);
1016         vhost_net_flush(n);
1017         vhost_dev_stop(&n->dev);
1018         vhost_dev_cleanup(&n->dev, false);
1019         vhost_net_vq_reset(n);
1020         if (tx_sock)
1021                 sockfd_put(tx_sock);
1022         if (rx_sock)
1023                 sockfd_put(rx_sock);
1024         /* Make sure no callbacks are outstanding */
1025         synchronize_rcu_bh();
1026         /* We do an extra flush before freeing memory,
1027          * since jobs can re-queue themselves. */
1028         vhost_net_flush(n);
1029         kfree(n->vqs[VHOST_NET_VQ_RX].rxq.queue);
1030         kfree(n->dev.vqs);
1031         kvfree(n);
1032         return 0;
1033 }
1034
1035 static struct socket *get_raw_socket(int fd)
1036 {
1037         struct {
1038                 struct sockaddr_ll sa;
1039                 char  buf[MAX_ADDR_LEN];
1040         } uaddr;
1041         int uaddr_len = sizeof uaddr, r;
1042         struct socket *sock = sockfd_lookup(fd, &r);
1043
1044         if (!sock)
1045                 return ERR_PTR(-ENOTSOCK);
1046
1047         /* Parameter checking */
1048         if (sock->sk->sk_type != SOCK_RAW) {
1049                 r = -ESOCKTNOSUPPORT;
1050                 goto err;
1051         }
1052
1053         r = sock->ops->getname(sock, (struct sockaddr *)&uaddr.sa,
1054                                &uaddr_len, 0);
1055         if (r)
1056                 goto err;
1057
1058         if (uaddr.sa.sll_family != AF_PACKET) {
1059                 r = -EPFNOSUPPORT;
1060                 goto err;
1061         }
1062         return sock;
1063 err:
1064         sockfd_put(sock);
1065         return ERR_PTR(r);
1066 }
1067
1068 static struct ptr_ring *get_tap_ptr_ring(int fd)
1069 {
1070         struct ptr_ring *ring;
1071         struct file *file = fget(fd);
1072
1073         if (!file)
1074                 return NULL;
1075         ring = tun_get_tx_ring(file);
1076         if (!IS_ERR(ring))
1077                 goto out;
1078         ring = tap_get_ptr_ring(file);
1079         if (!IS_ERR(ring))
1080                 goto out;
1081         ring = NULL;
1082 out:
1083         fput(file);
1084         return ring;
1085 }
1086
1087 static struct socket *get_tap_socket(int fd)
1088 {
1089         struct file *file = fget(fd);
1090         struct socket *sock;
1091
1092         if (!file)
1093                 return ERR_PTR(-EBADF);
1094         sock = tun_get_socket(file);
1095         if (!IS_ERR(sock))
1096                 return sock;
1097         sock = tap_get_socket(file);
1098         if (IS_ERR(sock))
1099                 fput(file);
1100         return sock;
1101 }
1102
1103 static struct socket *get_socket(int fd)
1104 {
1105         struct socket *sock;
1106
1107         /* special case to disable backend */
1108         if (fd == -1)
1109                 return NULL;
1110         sock = get_raw_socket(fd);
1111         if (!IS_ERR(sock))
1112                 return sock;
1113         sock = get_tap_socket(fd);
1114         if (!IS_ERR(sock))
1115                 return sock;
1116         return ERR_PTR(-ENOTSOCK);
1117 }
1118
1119 static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
1120 {
1121         struct socket *sock, *oldsock;
1122         struct vhost_virtqueue *vq;
1123         struct vhost_net_virtqueue *nvq;
1124         struct vhost_net_ubuf_ref *ubufs, *oldubufs = NULL;
1125         int r;
1126
1127         mutex_lock(&n->dev.mutex);
1128         r = vhost_dev_check_owner(&n->dev);
1129         if (r)
1130                 goto err;
1131
1132         if (index >= VHOST_NET_VQ_MAX) {
1133                 r = -ENOBUFS;
1134                 goto err;
1135         }
1136         vq = &n->vqs[index].vq;
1137         nvq = &n->vqs[index];
1138         mutex_lock(&vq->mutex);
1139
1140         /* Verify that ring has been setup correctly. */
1141         if (!vhost_vq_access_ok(vq)) {
1142                 r = -EFAULT;
1143                 goto err_vq;
1144         }
1145         sock = get_socket(fd);
1146         if (IS_ERR(sock)) {
1147                 r = PTR_ERR(sock);
1148                 goto err_vq;
1149         }
1150
1151         /* start polling new socket */
1152         oldsock = vq->private_data;
1153         if (sock != oldsock) {
1154                 ubufs = vhost_net_ubuf_alloc(vq,
1155                                              sock && vhost_sock_zcopy(sock));
1156                 if (IS_ERR(ubufs)) {
1157                         r = PTR_ERR(ubufs);
1158                         goto err_ubufs;
1159                 }
1160
1161                 vhost_net_disable_vq(n, vq);
1162                 vq->private_data = sock;
1163                 vhost_net_buf_unproduce(nvq);
1164                 if (index == VHOST_NET_VQ_RX)
1165                         nvq->rx_ring = get_tap_ptr_ring(fd);
1166                 r = vhost_vq_init_access(vq);
1167                 if (r)
1168                         goto err_used;
1169                 r = vhost_net_enable_vq(n, vq);
1170                 if (r)
1171                         goto err_used;
1172
1173                 oldubufs = nvq->ubufs;
1174                 nvq->ubufs = ubufs;
1175
1176                 n->tx_packets = 0;
1177                 n->tx_zcopy_err = 0;
1178                 n->tx_flush = false;
1179         }
1180
1181         mutex_unlock(&vq->mutex);
1182
1183         if (oldubufs) {
1184                 vhost_net_ubuf_put_wait_and_free(oldubufs);
1185                 mutex_lock(&vq->mutex);
1186                 vhost_zerocopy_signal_used(n, vq);
1187                 mutex_unlock(&vq->mutex);
1188         }
1189
1190         if (oldsock) {
1191                 vhost_net_flush_vq(n, index);
1192                 sockfd_put(oldsock);
1193         }
1194
1195         mutex_unlock(&n->dev.mutex);
1196         return 0;
1197
1198 err_used:
1199         vq->private_data = oldsock;
1200         vhost_net_enable_vq(n, vq);
1201         if (ubufs)
1202                 vhost_net_ubuf_put_wait_and_free(ubufs);
1203 err_ubufs:
1204         sockfd_put(sock);
1205 err_vq:
1206         mutex_unlock(&vq->mutex);
1207 err:
1208         mutex_unlock(&n->dev.mutex);
1209         return r;
1210 }
1211
1212 static long vhost_net_reset_owner(struct vhost_net *n)
1213 {
1214         struct socket *tx_sock = NULL;
1215         struct socket *rx_sock = NULL;
1216         long err;
1217         struct vhost_umem *umem;
1218
1219         mutex_lock(&n->dev.mutex);
1220         err = vhost_dev_check_owner(&n->dev);
1221         if (err)
1222                 goto done;
1223         umem = vhost_dev_reset_owner_prepare();
1224         if (!umem) {
1225                 err = -ENOMEM;
1226                 goto done;
1227         }
1228         vhost_net_stop(n, &tx_sock, &rx_sock);
1229         vhost_net_flush(n);
1230         vhost_dev_stop(&n->dev);
1231         vhost_dev_reset_owner(&n->dev, umem);
1232         vhost_net_vq_reset(n);
1233 done:
1234         mutex_unlock(&n->dev.mutex);
1235         if (tx_sock)
1236                 sockfd_put(tx_sock);
1237         if (rx_sock)
1238                 sockfd_put(rx_sock);
1239         return err;
1240 }
1241
1242 static int vhost_net_set_features(struct vhost_net *n, u64 features)
1243 {
1244         size_t vhost_hlen, sock_hlen, hdr_len;
1245         int i;
1246
1247         hdr_len = (features & ((1ULL << VIRTIO_NET_F_MRG_RXBUF) |
1248                                (1ULL << VIRTIO_F_VERSION_1))) ?
1249                         sizeof(struct virtio_net_hdr_mrg_rxbuf) :
1250                         sizeof(struct virtio_net_hdr);
1251         if (features & (1 << VHOST_NET_F_VIRTIO_NET_HDR)) {
1252                 /* vhost provides vnet_hdr */
1253                 vhost_hlen = hdr_len;
1254                 sock_hlen = 0;
1255         } else {
1256                 /* socket provides vnet_hdr */
1257                 vhost_hlen = 0;
1258                 sock_hlen = hdr_len;
1259         }
1260         mutex_lock(&n->dev.mutex);
1261         if ((features & (1 << VHOST_F_LOG_ALL)) &&
1262             !vhost_log_access_ok(&n->dev))
1263                 goto out_unlock;
1264
1265         if ((features & (1ULL << VIRTIO_F_IOMMU_PLATFORM))) {
1266                 if (vhost_init_device_iotlb(&n->dev, true))
1267                         goto out_unlock;
1268         }
1269
1270         for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
1271                 mutex_lock(&n->vqs[i].vq.mutex);
1272                 n->vqs[i].vq.acked_features = features;
1273                 n->vqs[i].vhost_hlen = vhost_hlen;
1274                 n->vqs[i].sock_hlen = sock_hlen;
1275                 mutex_unlock(&n->vqs[i].vq.mutex);
1276         }
1277         mutex_unlock(&n->dev.mutex);
1278         return 0;
1279
1280 out_unlock:
1281         mutex_unlock(&n->dev.mutex);
1282         return -EFAULT;
1283 }
1284
1285 static long vhost_net_set_owner(struct vhost_net *n)
1286 {
1287         int r;
1288
1289         mutex_lock(&n->dev.mutex);
1290         if (vhost_dev_has_owner(&n->dev)) {
1291                 r = -EBUSY;
1292                 goto out;
1293         }
1294         r = vhost_net_set_ubuf_info(n);
1295         if (r)
1296                 goto out;
1297         r = vhost_dev_set_owner(&n->dev);
1298         if (r)
1299                 vhost_net_clear_ubuf_info(n);
1300         vhost_net_flush(n);
1301 out:
1302         mutex_unlock(&n->dev.mutex);
1303         return r;
1304 }
1305
1306 static long vhost_net_ioctl(struct file *f, unsigned int ioctl,
1307                             unsigned long arg)
1308 {
1309         struct vhost_net *n = f->private_data;
1310         void __user *argp = (void __user *)arg;
1311         u64 __user *featurep = argp;
1312         struct vhost_vring_file backend;
1313         u64 features;
1314         int r;
1315
1316         switch (ioctl) {
1317         case VHOST_NET_SET_BACKEND:
1318                 if (copy_from_user(&backend, argp, sizeof backend))
1319                         return -EFAULT;
1320                 return vhost_net_set_backend(n, backend.index, backend.fd);
1321         case VHOST_GET_FEATURES:
1322                 features = VHOST_NET_FEATURES;
1323                 if (copy_to_user(featurep, &features, sizeof features))
1324                         return -EFAULT;
1325                 return 0;
1326         case VHOST_SET_FEATURES:
1327                 if (copy_from_user(&features, featurep, sizeof features))
1328                         return -EFAULT;
1329                 if (features & ~VHOST_NET_FEATURES)
1330                         return -EOPNOTSUPP;
1331                 return vhost_net_set_features(n, features);
1332         case VHOST_RESET_OWNER:
1333                 return vhost_net_reset_owner(n);
1334         case VHOST_SET_OWNER:
1335                 return vhost_net_set_owner(n);
1336         default:
1337                 mutex_lock(&n->dev.mutex);
1338                 r = vhost_dev_ioctl(&n->dev, ioctl, argp);
1339                 if (r == -ENOIOCTLCMD)
1340                         r = vhost_vring_ioctl(&n->dev, ioctl, argp);
1341                 else
1342                         vhost_net_flush(n);
1343                 mutex_unlock(&n->dev.mutex);
1344                 return r;
1345         }
1346 }
1347
1348 #ifdef CONFIG_COMPAT
1349 static long vhost_net_compat_ioctl(struct file *f, unsigned int ioctl,
1350                                    unsigned long arg)
1351 {
1352         return vhost_net_ioctl(f, ioctl, (unsigned long)compat_ptr(arg));
1353 }
1354 #endif
1355
1356 static ssize_t vhost_net_chr_read_iter(struct kiocb *iocb, struct iov_iter *to)
1357 {
1358         struct file *file = iocb->ki_filp;
1359         struct vhost_net *n = file->private_data;
1360         struct vhost_dev *dev = &n->dev;
1361         int noblock = file->f_flags & O_NONBLOCK;
1362
1363         return vhost_chr_read_iter(dev, to, noblock);
1364 }
1365
1366 static ssize_t vhost_net_chr_write_iter(struct kiocb *iocb,
1367                                         struct iov_iter *from)
1368 {
1369         struct file *file = iocb->ki_filp;
1370         struct vhost_net *n = file->private_data;
1371         struct vhost_dev *dev = &n->dev;
1372
1373         return vhost_chr_write_iter(dev, from);
1374 }
1375
1376 static __poll_t vhost_net_chr_poll(struct file *file, poll_table *wait)
1377 {
1378         struct vhost_net *n = file->private_data;
1379         struct vhost_dev *dev = &n->dev;
1380
1381         return vhost_chr_poll(file, dev, wait);
1382 }
1383
1384 static const struct file_operations vhost_net_fops = {
1385         .owner          = THIS_MODULE,
1386         .release        = vhost_net_release,
1387         .read_iter      = vhost_net_chr_read_iter,
1388         .write_iter     = vhost_net_chr_write_iter,
1389         .poll           = vhost_net_chr_poll,
1390         .unlocked_ioctl = vhost_net_ioctl,
1391 #ifdef CONFIG_COMPAT
1392         .compat_ioctl   = vhost_net_compat_ioctl,
1393 #endif
1394         .open           = vhost_net_open,
1395         .llseek         = noop_llseek,
1396 };
1397
1398 static struct miscdevice vhost_net_misc = {
1399         .minor = VHOST_NET_MINOR,
1400         .name = "vhost-net",
1401         .fops = &vhost_net_fops,
1402 };
1403
1404 static int vhost_net_init(void)
1405 {
1406         if (experimental_zcopytx)
1407                 vhost_net_enable_zcopy(VHOST_NET_VQ_TX);
1408         return misc_register(&vhost_net_misc);
1409 }
1410 module_init(vhost_net_init);
1411
1412 static void vhost_net_exit(void)
1413 {
1414         misc_deregister(&vhost_net_misc);
1415 }
1416 module_exit(vhost_net_exit);
1417
1418 MODULE_VERSION("0.0.1");
1419 MODULE_LICENSE("GPL v2");
1420 MODULE_AUTHOR("Michael S. Tsirkin");
1421 MODULE_DESCRIPTION("Host kernel accelerator for virtio net");
1422 MODULE_ALIAS_MISCDEV(VHOST_NET_MINOR);
1423 MODULE_ALIAS("devname:vhost-net");