Version:  2.0.40 2.2.26 2.4.37 3.4 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.16 3.17 3.18 3.19 4.0

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_VERSION_1),
 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 /* Expects to be always run from workqueue - which acts as
292  * read-size critical section for our kind of RCU. */
293 static void handle_tx(struct vhost_net *net)
294 {
295         struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
296         struct vhost_virtqueue *vq = &nvq->vq;
297         unsigned out, in;
298         int head;
299         struct msghdr msg = {
300                 .msg_name = NULL,
301                 .msg_namelen = 0,
302                 .msg_control = NULL,
303                 .msg_controllen = 0,
304                 .msg_flags = MSG_DONTWAIT,
305         };
306         size_t len, total_len = 0;
307         int err;
308         size_t hdr_size;
309         struct socket *sock;
310         struct vhost_net_ubuf_ref *uninitialized_var(ubufs);
311         bool zcopy, zcopy_used;
312 
313         mutex_lock(&vq->mutex);
314         sock = vq->private_data;
315         if (!sock)
316                 goto out;
317 
318         vhost_disable_notify(&net->dev, vq);
319 
320         hdr_size = nvq->vhost_hlen;
321         zcopy = nvq->ubufs;
322 
323         for (;;) {
324                 /* Release DMAs done buffers first */
325                 if (zcopy)
326                         vhost_zerocopy_signal_used(net, vq);
327 
328                 /* If more outstanding DMAs, queue the work.
329                  * Handle upend_idx wrap around
330                  */
331                 if (unlikely((nvq->upend_idx + vq->num - VHOST_MAX_PEND)
332                               % UIO_MAXIOV == nvq->done_idx))
333                         break;
334 
335                 head = vhost_get_vq_desc(vq, vq->iov,
336                                          ARRAY_SIZE(vq->iov),
337                                          &out, &in,
338                                          NULL, NULL);
339                 /* On error, stop handling until the next kick. */
340                 if (unlikely(head < 0))
341                         break;
342                 /* Nothing new?  Wait for eventfd to tell us they refilled. */
343                 if (head == vq->num) {
344                         if (unlikely(vhost_enable_notify(&net->dev, vq))) {
345                                 vhost_disable_notify(&net->dev, vq);
346                                 continue;
347                         }
348                         break;
349                 }
350                 if (in) {
351                         vq_err(vq, "Unexpected descriptor format for TX: "
352                                "out %d, int %d\n", out, in);
353                         break;
354                 }
355                 /* Skip header. TODO: support TSO. */
356                 len = iov_length(vq->iov, out);
357                 iov_iter_init(&msg.msg_iter, WRITE, vq->iov, out, len);
358                 iov_iter_advance(&msg.msg_iter, hdr_size);
359                 /* Sanity check */
360                 if (!iov_iter_count(&msg.msg_iter)) {
361                         vq_err(vq, "Unexpected header len for TX: "
362                                "%zd expected %zd\n",
363                                len, hdr_size);
364                         break;
365                 }
366                 len = iov_iter_count(&msg.msg_iter);
367 
368                 zcopy_used = zcopy && len >= VHOST_GOODCOPY_LEN
369                                    && (nvq->upend_idx + 1) % UIO_MAXIOV !=
370                                       nvq->done_idx
371                                    && vhost_net_tx_select_zcopy(net);
372 
373                 /* use msg_control to pass vhost zerocopy ubuf info to skb */
374                 if (zcopy_used) {
375                         struct ubuf_info *ubuf;
376                         ubuf = nvq->ubuf_info + nvq->upend_idx;
377 
378                         vq->heads[nvq->upend_idx].id = cpu_to_vhost32(vq, head);
379                         vq->heads[nvq->upend_idx].len = VHOST_DMA_IN_PROGRESS;
380                         ubuf->callback = vhost_zerocopy_callback;
381                         ubuf->ctx = nvq->ubufs;
382                         ubuf->desc = nvq->upend_idx;
383                         msg.msg_control = ubuf;
384                         msg.msg_controllen = sizeof(ubuf);
385                         ubufs = nvq->ubufs;
386                         atomic_inc(&ubufs->refcount);
387                         nvq->upend_idx = (nvq->upend_idx + 1) % UIO_MAXIOV;
388                 } else {
389                         msg.msg_control = NULL;
390                         ubufs = NULL;
391                 }
392                 /* TODO: Check specific error and bomb out unless ENOBUFS? */
393                 err = sock->ops->sendmsg(NULL, sock, &msg, len);
394                 if (unlikely(err < 0)) {
395                         if (zcopy_used) {
396                                 vhost_net_ubuf_put(ubufs);
397                                 nvq->upend_idx = ((unsigned)nvq->upend_idx - 1)
398                                         % UIO_MAXIOV;
399                         }
400                         vhost_discard_vq_desc(vq, 1);
401                         break;
402                 }
403                 if (err != len)
404                         pr_debug("Truncated TX packet: "
405                                  " len %d != %zd\n", err, len);
406                 if (!zcopy_used)
407                         vhost_add_used_and_signal(&net->dev, vq, head, 0);
408                 else
409                         vhost_zerocopy_signal_used(net, vq);
410                 total_len += len;
411                 vhost_net_tx_packet(net);
412                 if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
413                         vhost_poll_queue(&vq->poll);
414                         break;
415                 }
416         }
417 out:
418         mutex_unlock(&vq->mutex);
419 }
420 
421 static int peek_head_len(struct sock *sk)
422 {
423         struct sk_buff *head;
424         int len = 0;
425         unsigned long flags;
426 
427         spin_lock_irqsave(&sk->sk_receive_queue.lock, flags);
428         head = skb_peek(&sk->sk_receive_queue);
429         if (likely(head)) {
430                 len = head->len;
431                 if (skb_vlan_tag_present(head))
432                         len += VLAN_HLEN;
433         }
434 
435         spin_unlock_irqrestore(&sk->sk_receive_queue.lock, flags);
436         return len;
437 }
438 
439 /* This is a multi-buffer version of vhost_get_desc, that works if
440  *      vq has read descriptors only.
441  * @vq          - the relevant virtqueue
442  * @datalen     - data length we'll be reading
443  * @iovcount    - returned count of io vectors we fill
444  * @log         - vhost log
445  * @log_num     - log offset
446  * @quota       - headcount quota, 1 for big buffer
447  *      returns number of buffer heads allocated, negative on error
448  */
449 static int get_rx_bufs(struct vhost_virtqueue *vq,
450                        struct vring_used_elem *heads,
451                        int datalen,
452                        unsigned *iovcount,
453                        struct vhost_log *log,
454                        unsigned *log_num,
455                        unsigned int quota)
456 {
457         unsigned int out, in;
458         int seg = 0;
459         int headcount = 0;
460         unsigned d;
461         int r, nlogs = 0;
462         /* len is always initialized before use since we are always called with
463          * datalen > 0.
464          */
465         u32 uninitialized_var(len);
466 
467         while (datalen > 0 && headcount < quota) {
468                 if (unlikely(seg >= UIO_MAXIOV)) {
469                         r = -ENOBUFS;
470                         goto err;
471                 }
472                 r = vhost_get_vq_desc(vq, vq->iov + seg,
473                                       ARRAY_SIZE(vq->iov) - seg, &out,
474                                       &in, log, log_num);
475                 if (unlikely(r < 0))
476                         goto err;
477 
478                 d = r;
479                 if (d == vq->num) {
480                         r = 0;
481                         goto err;
482                 }
483                 if (unlikely(out || in <= 0)) {
484                         vq_err(vq, "unexpected descriptor format for RX: "
485                                 "out %d, in %d\n", out, in);
486                         r = -EINVAL;
487                         goto err;
488                 }
489                 if (unlikely(log)) {
490                         nlogs += *log_num;
491                         log += *log_num;
492                 }
493                 heads[headcount].id = cpu_to_vhost32(vq, d);
494                 len = iov_length(vq->iov + seg, in);
495                 heads[headcount].len = cpu_to_vhost32(vq, len);
496                 datalen -= len;
497                 ++headcount;
498                 seg += in;
499         }
500         heads[headcount - 1].len = cpu_to_vhost32(vq, len + datalen);
501         *iovcount = seg;
502         if (unlikely(log))
503                 *log_num = nlogs;
504 
505         /* Detect overrun */
506         if (unlikely(datalen > 0)) {
507                 r = UIO_MAXIOV + 1;
508                 goto err;
509         }
510         return headcount;
511 err:
512         vhost_discard_vq_desc(vq, headcount);
513         return r;
514 }
515 
516 /* Expects to be always run from workqueue - which acts as
517  * read-size critical section for our kind of RCU. */
518 static void handle_rx(struct vhost_net *net)
519 {
520         struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_RX];
521         struct vhost_virtqueue *vq = &nvq->vq;
522         unsigned uninitialized_var(in), log;
523         struct vhost_log *vq_log;
524         struct msghdr msg = {
525                 .msg_name = NULL,
526                 .msg_namelen = 0,
527                 .msg_control = NULL, /* FIXME: get and handle RX aux data. */
528                 .msg_controllen = 0,
529                 .msg_flags = MSG_DONTWAIT,
530         };
531         struct virtio_net_hdr hdr = {
532                 .flags = 0,
533                 .gso_type = VIRTIO_NET_HDR_GSO_NONE
534         };
535         size_t total_len = 0;
536         int err, mergeable;
537         s16 headcount;
538         size_t vhost_hlen, sock_hlen;
539         size_t vhost_len, sock_len;
540         struct socket *sock;
541         struct iov_iter fixup;
542         __virtio16 num_buffers;
543 
544         mutex_lock(&vq->mutex);
545         sock = vq->private_data;
546         if (!sock)
547                 goto out;
548         vhost_disable_notify(&net->dev, vq);
549 
550         vhost_hlen = nvq->vhost_hlen;
551         sock_hlen = nvq->sock_hlen;
552 
553         vq_log = unlikely(vhost_has_feature(vq, VHOST_F_LOG_ALL)) ?
554                 vq->log : NULL;
555         mergeable = vhost_has_feature(vq, VIRTIO_NET_F_MRG_RXBUF);
556 
557         while ((sock_len = peek_head_len(sock->sk))) {
558                 sock_len += sock_hlen;
559                 vhost_len = sock_len + vhost_hlen;
560                 headcount = get_rx_bufs(vq, vq->heads, vhost_len,
561                                         &in, vq_log, &log,
562                                         likely(mergeable) ? UIO_MAXIOV : 1);
563                 /* On error, stop handling until the next kick. */
564                 if (unlikely(headcount < 0))
565                         break;
566                 /* On overrun, truncate and discard */
567                 if (unlikely(headcount > UIO_MAXIOV)) {
568                         iov_iter_init(&msg.msg_iter, READ, vq->iov, 1, 1);
569                         err = sock->ops->recvmsg(NULL, sock, &msg,
570                                                  1, MSG_DONTWAIT | MSG_TRUNC);
571                         pr_debug("Discarded rx packet: len %zd\n", sock_len);
572                         continue;
573                 }
574                 /* OK, now we need to know about added descriptors. */
575                 if (!headcount) {
576                         if (unlikely(vhost_enable_notify(&net->dev, vq))) {
577                                 /* They have slipped one in as we were
578                                  * doing that: check again. */
579                                 vhost_disable_notify(&net->dev, vq);
580                                 continue;
581                         }
582                         /* Nothing new?  Wait for eventfd to tell us
583                          * they refilled. */
584                         break;
585                 }
586                 /* We don't need to be notified again. */
587                 iov_iter_init(&msg.msg_iter, READ, vq->iov, in, vhost_len);
588                 fixup = msg.msg_iter;
589                 if (unlikely((vhost_hlen))) {
590                         /* We will supply the header ourselves
591                          * TODO: support TSO.
592                          */
593                         iov_iter_advance(&msg.msg_iter, vhost_hlen);
594                 }
595                 err = sock->ops->recvmsg(NULL, sock, &msg,
596                                          sock_len, MSG_DONTWAIT | MSG_TRUNC);
597                 /* Userspace might have consumed the packet meanwhile:
598                  * it's not supposed to do this usually, but might be hard
599                  * to prevent. Discard data we got (if any) and keep going. */
600                 if (unlikely(err != sock_len)) {
601                         pr_debug("Discarded rx packet: "
602                                  " len %d, expected %zd\n", err, sock_len);
603                         vhost_discard_vq_desc(vq, headcount);
604                         continue;
605                 }
606                 /* Supply virtio_net_hdr if VHOST_NET_F_VIRTIO_NET_HDR */
607                 if (unlikely(vhost_hlen)) {
608                         if (copy_to_iter(&hdr, sizeof(hdr),
609                                          &fixup) != sizeof(hdr)) {
610                                 vq_err(vq, "Unable to write vnet_hdr "
611                                        "at addr %p\n", vq->iov->iov_base);
612                                 break;
613                         }
614                 } else {
615                         /* Header came from socket; we'll need to patch
616                          * ->num_buffers over if VIRTIO_NET_F_MRG_RXBUF
617                          */
618                         iov_iter_advance(&fixup, sizeof(hdr));
619                 }
620                 /* TODO: Should check and handle checksum. */
621 
622                 num_buffers = cpu_to_vhost16(vq, headcount);
623                 if (likely(mergeable) &&
624                     copy_to_iter(&num_buffers, sizeof num_buffers,
625                                  &fixup) != sizeof num_buffers) {
626                         vq_err(vq, "Failed num_buffers write");
627                         vhost_discard_vq_desc(vq, headcount);
628                         break;
629                 }
630                 vhost_add_used_and_signal_n(&net->dev, vq, vq->heads,
631                                             headcount);
632                 if (unlikely(vq_log))
633                         vhost_log_write(vq, vq_log, log, vhost_len);
634                 total_len += vhost_len;
635                 if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
636                         vhost_poll_queue(&vq->poll);
637                         break;
638                 }
639         }
640 out:
641         mutex_unlock(&vq->mutex);
642 }
643 
644 static void handle_tx_kick(struct vhost_work *work)
645 {
646         struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
647                                                   poll.work);
648         struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev);
649 
650         handle_tx(net);
651 }
652 
653 static void handle_rx_kick(struct vhost_work *work)
654 {
655         struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
656                                                   poll.work);
657         struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev);
658 
659         handle_rx(net);
660 }
661 
662 static void handle_tx_net(struct vhost_work *work)
663 {
664         struct vhost_net *net = container_of(work, struct vhost_net,
665                                              poll[VHOST_NET_VQ_TX].work);
666         handle_tx(net);
667 }
668 
669 static void handle_rx_net(struct vhost_work *work)
670 {
671         struct vhost_net *net = container_of(work, struct vhost_net,
672                                              poll[VHOST_NET_VQ_RX].work);
673         handle_rx(net);
674 }
675 
676 static int vhost_net_open(struct inode *inode, struct file *f)
677 {
678         struct vhost_net *n;
679         struct vhost_dev *dev;
680         struct vhost_virtqueue **vqs;
681         int i;
682 
683         n = kmalloc(sizeof *n, GFP_KERNEL | __GFP_NOWARN | __GFP_REPEAT);
684         if (!n) {
685                 n = vmalloc(sizeof *n);
686                 if (!n)
687                         return -ENOMEM;
688         }
689         vqs = kmalloc(VHOST_NET_VQ_MAX * sizeof(*vqs), GFP_KERNEL);
690         if (!vqs) {
691                 kvfree(n);
692                 return -ENOMEM;
693         }
694 
695         dev = &n->dev;
696         vqs[VHOST_NET_VQ_TX] = &n->vqs[VHOST_NET_VQ_TX].vq;
697         vqs[VHOST_NET_VQ_RX] = &n->vqs[VHOST_NET_VQ_RX].vq;
698         n->vqs[VHOST_NET_VQ_TX].vq.handle_kick = handle_tx_kick;
699         n->vqs[VHOST_NET_VQ_RX].vq.handle_kick = handle_rx_kick;
700         for (i = 0; i < VHOST_NET_VQ_MAX; i++) {
701                 n->vqs[i].ubufs = NULL;
702                 n->vqs[i].ubuf_info = NULL;
703                 n->vqs[i].upend_idx = 0;
704                 n->vqs[i].done_idx = 0;
705                 n->vqs[i].vhost_hlen = 0;
706                 n->vqs[i].sock_hlen = 0;
707         }
708         vhost_dev_init(dev, vqs, VHOST_NET_VQ_MAX);
709 
710         vhost_poll_init(n->poll + VHOST_NET_VQ_TX, handle_tx_net, POLLOUT, dev);
711         vhost_poll_init(n->poll + VHOST_NET_VQ_RX, handle_rx_net, POLLIN, dev);
712 
713         f->private_data = n;
714 
715         return 0;
716 }
717 
718 static void vhost_net_disable_vq(struct vhost_net *n,
719                                  struct vhost_virtqueue *vq)
720 {
721         struct vhost_net_virtqueue *nvq =
722                 container_of(vq, struct vhost_net_virtqueue, vq);
723         struct vhost_poll *poll = n->poll + (nvq - n->vqs);
724         if (!vq->private_data)
725                 return;
726         vhost_poll_stop(poll);
727 }
728 
729 static int vhost_net_enable_vq(struct vhost_net *n,
730                                 struct vhost_virtqueue *vq)
731 {
732         struct vhost_net_virtqueue *nvq =
733                 container_of(vq, struct vhost_net_virtqueue, vq);
734         struct vhost_poll *poll = n->poll + (nvq - n->vqs);
735         struct socket *sock;
736 
737         sock = vq->private_data;
738         if (!sock)
739                 return 0;
740 
741         return vhost_poll_start(poll, sock->file);
742 }
743 
744 static struct socket *vhost_net_stop_vq(struct vhost_net *n,
745                                         struct vhost_virtqueue *vq)
746 {
747         struct socket *sock;
748 
749         mutex_lock(&vq->mutex);
750         sock = vq->private_data;
751         vhost_net_disable_vq(n, vq);
752         vq->private_data = NULL;
753         mutex_unlock(&vq->mutex);
754         return sock;
755 }
756 
757 static void vhost_net_stop(struct vhost_net *n, struct socket **tx_sock,
758                            struct socket **rx_sock)
759 {
760         *tx_sock = vhost_net_stop_vq(n, &n->vqs[VHOST_NET_VQ_TX].vq);
761         *rx_sock = vhost_net_stop_vq(n, &n->vqs[VHOST_NET_VQ_RX].vq);
762 }
763 
764 static void vhost_net_flush_vq(struct vhost_net *n, int index)
765 {
766         vhost_poll_flush(n->poll + index);
767         vhost_poll_flush(&n->vqs[index].vq.poll);
768 }
769 
770 static void vhost_net_flush(struct vhost_net *n)
771 {
772         vhost_net_flush_vq(n, VHOST_NET_VQ_TX);
773         vhost_net_flush_vq(n, VHOST_NET_VQ_RX);
774         if (n->vqs[VHOST_NET_VQ_TX].ubufs) {
775                 mutex_lock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
776                 n->tx_flush = true;
777                 mutex_unlock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
778                 /* Wait for all lower device DMAs done. */
779                 vhost_net_ubuf_put_and_wait(n->vqs[VHOST_NET_VQ_TX].ubufs);
780                 mutex_lock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
781                 n->tx_flush = false;
782                 atomic_set(&n->vqs[VHOST_NET_VQ_TX].ubufs->refcount, 1);
783                 mutex_unlock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
784         }
785 }
786 
787 static int vhost_net_release(struct inode *inode, struct file *f)
788 {
789         struct vhost_net *n = f->private_data;
790         struct socket *tx_sock;
791         struct socket *rx_sock;
792 
793         vhost_net_stop(n, &tx_sock, &rx_sock);
794         vhost_net_flush(n);
795         vhost_dev_stop(&n->dev);
796         vhost_dev_cleanup(&n->dev, false);
797         vhost_net_vq_reset(n);
798         if (tx_sock)
799                 sockfd_put(tx_sock);
800         if (rx_sock)
801                 sockfd_put(rx_sock);
802         /* Make sure no callbacks are outstanding */
803         synchronize_rcu_bh();
804         /* We do an extra flush before freeing memory,
805          * since jobs can re-queue themselves. */
806         vhost_net_flush(n);
807         kfree(n->dev.vqs);
808         kvfree(n);
809         return 0;
810 }
811 
812 static struct socket *get_raw_socket(int fd)
813 {
814         struct {
815                 struct sockaddr_ll sa;
816                 char  buf[MAX_ADDR_LEN];
817         } uaddr;
818         int uaddr_len = sizeof uaddr, r;
819         struct socket *sock = sockfd_lookup(fd, &r);
820 
821         if (!sock)
822                 return ERR_PTR(-ENOTSOCK);
823 
824         /* Parameter checking */
825         if (sock->sk->sk_type != SOCK_RAW) {
826                 r = -ESOCKTNOSUPPORT;
827                 goto err;
828         }
829 
830         r = sock->ops->getname(sock, (struct sockaddr *)&uaddr.sa,
831                                &uaddr_len, 0);
832         if (r)
833                 goto err;
834 
835         if (uaddr.sa.sll_family != AF_PACKET) {
836                 r = -EPFNOSUPPORT;
837                 goto err;
838         }
839         return sock;
840 err:
841         sockfd_put(sock);
842         return ERR_PTR(r);
843 }
844 
845 static struct socket *get_tap_socket(int fd)
846 {
847         struct file *file = fget(fd);
848         struct socket *sock;
849 
850         if (!file)
851                 return ERR_PTR(-EBADF);
852         sock = tun_get_socket(file);
853         if (!IS_ERR(sock))
854                 return sock;
855         sock = macvtap_get_socket(file);
856         if (IS_ERR(sock))
857                 fput(file);
858         return sock;
859 }
860 
861 static struct socket *get_socket(int fd)
862 {
863         struct socket *sock;
864 
865         /* special case to disable backend */
866         if (fd == -1)
867                 return NULL;
868         sock = get_raw_socket(fd);
869         if (!IS_ERR(sock))
870                 return sock;
871         sock = get_tap_socket(fd);
872         if (!IS_ERR(sock))
873                 return sock;
874         return ERR_PTR(-ENOTSOCK);
875 }
876 
877 static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
878 {
879         struct socket *sock, *oldsock;
880         struct vhost_virtqueue *vq;
881         struct vhost_net_virtqueue *nvq;
882         struct vhost_net_ubuf_ref *ubufs, *oldubufs = NULL;
883         int r;
884 
885         mutex_lock(&n->dev.mutex);
886         r = vhost_dev_check_owner(&n->dev);
887         if (r)
888                 goto err;
889 
890         if (index >= VHOST_NET_VQ_MAX) {
891                 r = -ENOBUFS;
892                 goto err;
893         }
894         vq = &n->vqs[index].vq;
895         nvq = &n->vqs[index];
896         mutex_lock(&vq->mutex);
897 
898         /* Verify that ring has been setup correctly. */
899         if (!vhost_vq_access_ok(vq)) {
900                 r = -EFAULT;
901                 goto err_vq;
902         }
903         sock = get_socket(fd);
904         if (IS_ERR(sock)) {
905                 r = PTR_ERR(sock);
906                 goto err_vq;
907         }
908 
909         /* start polling new socket */
910         oldsock = vq->private_data;
911         if (sock != oldsock) {
912                 ubufs = vhost_net_ubuf_alloc(vq,
913                                              sock && vhost_sock_zcopy(sock));
914                 if (IS_ERR(ubufs)) {
915                         r = PTR_ERR(ubufs);
916                         goto err_ubufs;
917                 }
918 
919                 vhost_net_disable_vq(n, vq);
920                 vq->private_data = sock;
921                 r = vhost_init_used(vq);
922                 if (r)
923                         goto err_used;
924                 r = vhost_net_enable_vq(n, vq);
925                 if (r)
926                         goto err_used;
927 
928                 oldubufs = nvq->ubufs;
929                 nvq->ubufs = ubufs;
930 
931                 n->tx_packets = 0;
932                 n->tx_zcopy_err = 0;
933                 n->tx_flush = false;
934         }
935 
936         mutex_unlock(&vq->mutex);
937 
938         if (oldubufs) {
939                 vhost_net_ubuf_put_wait_and_free(oldubufs);
940                 mutex_lock(&vq->mutex);
941                 vhost_zerocopy_signal_used(n, vq);
942                 mutex_unlock(&vq->mutex);
943         }
944 
945         if (oldsock) {
946                 vhost_net_flush_vq(n, index);
947                 sockfd_put(oldsock);
948         }
949 
950         mutex_unlock(&n->dev.mutex);
951         return 0;
952 
953 err_used:
954         vq->private_data = oldsock;
955         vhost_net_enable_vq(n, vq);
956         if (ubufs)
957                 vhost_net_ubuf_put_wait_and_free(ubufs);
958 err_ubufs:
959         sockfd_put(sock);
960 err_vq:
961         mutex_unlock(&vq->mutex);
962 err:
963         mutex_unlock(&n->dev.mutex);
964         return r;
965 }
966 
967 static long vhost_net_reset_owner(struct vhost_net *n)
968 {
969         struct socket *tx_sock = NULL;
970         struct socket *rx_sock = NULL;
971         long err;
972         struct vhost_memory *memory;
973 
974         mutex_lock(&n->dev.mutex);
975         err = vhost_dev_check_owner(&n->dev);
976         if (err)
977                 goto done;
978         memory = vhost_dev_reset_owner_prepare();
979         if (!memory) {
980                 err = -ENOMEM;
981                 goto done;
982         }
983         vhost_net_stop(n, &tx_sock, &rx_sock);
984         vhost_net_flush(n);
985         vhost_dev_reset_owner(&n->dev, memory);
986         vhost_net_vq_reset(n);
987 done:
988         mutex_unlock(&n->dev.mutex);
989         if (tx_sock)
990                 sockfd_put(tx_sock);
991         if (rx_sock)
992                 sockfd_put(rx_sock);
993         return err;
994 }
995 
996 static int vhost_net_set_features(struct vhost_net *n, u64 features)
997 {
998         size_t vhost_hlen, sock_hlen, hdr_len;
999         int i;
1000 
1001         hdr_len = (features & ((1ULL << VIRTIO_NET_F_MRG_RXBUF) |
1002                                (1ULL << VIRTIO_F_VERSION_1))) ?
1003                         sizeof(struct virtio_net_hdr_mrg_rxbuf) :
1004                         sizeof(struct virtio_net_hdr);
1005         if (features & (1 << VHOST_NET_F_VIRTIO_NET_HDR)) {
1006                 /* vhost provides vnet_hdr */
1007                 vhost_hlen = hdr_len;
1008                 sock_hlen = 0;
1009         } else {
1010                 /* socket provides vnet_hdr */
1011                 vhost_hlen = 0;
1012                 sock_hlen = hdr_len;
1013         }
1014         mutex_lock(&n->dev.mutex);
1015         if ((features & (1 << VHOST_F_LOG_ALL)) &&
1016             !vhost_log_access_ok(&n->dev)) {
1017                 mutex_unlock(&n->dev.mutex);
1018                 return -EFAULT;
1019         }
1020         for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
1021                 mutex_lock(&n->vqs[i].vq.mutex);
1022                 n->vqs[i].vq.acked_features = features;
1023                 n->vqs[i].vhost_hlen = vhost_hlen;
1024                 n->vqs[i].sock_hlen = sock_hlen;
1025                 mutex_unlock(&n->vqs[i].vq.mutex);
1026         }
1027         mutex_unlock(&n->dev.mutex);
1028         return 0;
1029 }
1030 
1031 static long vhost_net_set_owner(struct vhost_net *n)
1032 {
1033         int r;
1034 
1035         mutex_lock(&n->dev.mutex);
1036         if (vhost_dev_has_owner(&n->dev)) {
1037                 r = -EBUSY;
1038                 goto out;
1039         }
1040         r = vhost_net_set_ubuf_info(n);
1041         if (r)
1042                 goto out;
1043         r = vhost_dev_set_owner(&n->dev);
1044         if (r)
1045                 vhost_net_clear_ubuf_info(n);
1046         vhost_net_flush(n);
1047 out:
1048         mutex_unlock(&n->dev.mutex);
1049         return r;
1050 }
1051 
1052 static long vhost_net_ioctl(struct file *f, unsigned int ioctl,
1053                             unsigned long arg)
1054 {
1055         struct vhost_net *n = f->private_data;
1056         void __user *argp = (void __user *)arg;
1057         u64 __user *featurep = argp;
1058         struct vhost_vring_file backend;
1059         u64 features;
1060         int r;
1061 
1062         switch (ioctl) {
1063         case VHOST_NET_SET_BACKEND:
1064                 if (copy_from_user(&backend, argp, sizeof backend))
1065                         return -EFAULT;
1066                 return vhost_net_set_backend(n, backend.index, backend.fd);
1067         case VHOST_GET_FEATURES:
1068                 features = VHOST_NET_FEATURES;
1069                 if (copy_to_user(featurep, &features, sizeof features))
1070                         return -EFAULT;
1071                 return 0;
1072         case VHOST_SET_FEATURES:
1073                 if (copy_from_user(&features, featurep, sizeof features))
1074                         return -EFAULT;
1075                 if (features & ~VHOST_NET_FEATURES)
1076                         return -EOPNOTSUPP;
1077                 return vhost_net_set_features(n, features);
1078         case VHOST_RESET_OWNER:
1079                 return vhost_net_reset_owner(n);
1080         case VHOST_SET_OWNER:
1081                 return vhost_net_set_owner(n);
1082         default:
1083                 mutex_lock(&n->dev.mutex);
1084                 r = vhost_dev_ioctl(&n->dev, ioctl, argp);
1085                 if (r == -ENOIOCTLCMD)
1086                         r = vhost_vring_ioctl(&n->dev, ioctl, argp);
1087                 else
1088                         vhost_net_flush(n);
1089                 mutex_unlock(&n->dev.mutex);
1090                 return r;
1091         }
1092 }
1093 
1094 #ifdef CONFIG_COMPAT
1095 static long vhost_net_compat_ioctl(struct file *f, unsigned int ioctl,
1096                                    unsigned long arg)
1097 {
1098         return vhost_net_ioctl(f, ioctl, (unsigned long)compat_ptr(arg));
1099 }
1100 #endif
1101 
1102 static const struct file_operations vhost_net_fops = {
1103         .owner          = THIS_MODULE,
1104         .release        = vhost_net_release,
1105         .unlocked_ioctl = vhost_net_ioctl,
1106 #ifdef CONFIG_COMPAT
1107         .compat_ioctl   = vhost_net_compat_ioctl,
1108 #endif
1109         .open           = vhost_net_open,
1110         .llseek         = noop_llseek,
1111 };
1112 
1113 static struct miscdevice vhost_net_misc = {
1114         .minor = VHOST_NET_MINOR,
1115         .name = "vhost-net",
1116         .fops = &vhost_net_fops,
1117 };
1118 
1119 static int vhost_net_init(void)
1120 {
1121         if (experimental_zcopytx)
1122                 vhost_net_enable_zcopy(VHOST_NET_VQ_TX);
1123         return misc_register(&vhost_net_misc);
1124 }
1125 module_init(vhost_net_init);
1126 
1127 static void vhost_net_exit(void)
1128 {
1129         misc_deregister(&vhost_net_misc);
1130 }
1131 module_exit(vhost_net_exit);
1132 
1133 MODULE_VERSION("0.0.1");
1134 MODULE_LICENSE("GPL v2");
1135 MODULE_AUTHOR("Michael S. Tsirkin");
1136 MODULE_DESCRIPTION("Host kernel accelerator for virtio net");
1137 MODULE_ALIAS_MISCDEV(VHOST_NET_MINOR);
1138 MODULE_ALIAS("devname:vhost-net");
1139 

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