drivers/vhost/net.c

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