Version:  2.0.40 2.2.26 2.4.37 3.10 3.11 3.12 3.13 3.14 3.15 3.16 3.17 3.18 3.19 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7

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

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