drivers/vhost/net.c

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