Version:  2.0.40 2.2.26 2.4.37 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 4.8

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

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