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/rcupdate.h>
  19 #include <linux/file.h>
  20 #include <linux/slab.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
  28 #include <net/sock.h>
  29
  30 #include "vhost.h"
  31
  32 static int experimental_zcopytx;
  33 module_param(experimental_zcopytx, int, 0444);
  34 MODULE_PARM_DESC(experimental_zcopytx, "Enable Experimental Zero Copy TX");
  35
  36 /* Max number of bytes transferred before requeueing the job.
  37  * Using this limit prevents one virtqueue from starving others. */
  38 #define VHOST_NET_WEIGHT 0x80000
  39
  40 /* MAX number of TX used buffers for outstanding zerocopy */
  41 #define VHOST_MAX_PEND 128
  42 #define VHOST_GOODCOPY_LEN 256
  43
  44 enum {
  45         VHOST_NET_VQ_RX = 0,
  46         VHOST_NET_VQ_TX = 1,
  47         VHOST_NET_VQ_MAX = 2,
  48 };
  49
  50 enum vhost_net_poll_state {
  51         VHOST_NET_POLL_DISABLED = 0,
  52         VHOST_NET_POLL_STARTED = 1,
  53         VHOST_NET_POLL_STOPPED = 2,
  54 };
  55
  56 struct vhost_net {
  57         struct vhost_dev dev;
  58         struct vhost_virtqueue vqs[VHOST_NET_VQ_MAX];
  59         struct vhost_poll poll[VHOST_NET_VQ_MAX];
  60         /* Tells us whether we are polling a socket for TX.
  61          * We only do this when socket buffer fills up.
  62          * Protected by tx vq lock. */
  63         enum vhost_net_poll_state tx_poll_state;
  64 };
  65
  66 static bool vhost_sock_zcopy(struct socket *sock)
  67 {
  68         return unlikely(experimental_zcopytx) &&
  69                 sock_flag(sock->sk, SOCK_ZEROCOPY);
  70 }
  71
  72 /* Pop first len bytes from iovec. Return number of segments used. */
  73 static int move_iovec_hdr(struct iovec *from, struct iovec *to,
  74                           size_t len, int iov_count)
  75 {
  76         int seg = 0;
  77         size_t size;
  78
  79         while (len && seg < iov_count) {
  80                 size = min(from->iov_len, len);
  81                 to->iov_base = from->iov_base;
  82                 to->iov_len = size;
  83                 from->iov_len -= size;
  84                 from->iov_base += size;
  85                 len -= size;
  86                 ++from;
  87                 ++to;
  88                 ++seg;
  89         }
  90         return seg;
  91 }
  92 /* Copy iovec entries for len bytes from iovec. */
  93 static void copy_iovec_hdr(const struct iovec *from, struct iovec *to,
  94                            size_t len, int iovcount)
  95 {
  96         int seg = 0;
  97         size_t size;
  98
  99         while (len && seg < iovcount) {
 100                 size = min(from->iov_len, len);
 101                 to->iov_base = from->iov_base;
 102                 to->iov_len = size;
 103                 len -= size;
 104                 ++from;
 105                 ++to;
 106                 ++seg;
 107         }
 108 }
 109
 110 /* Caller must have TX VQ lock */
 111 static void tx_poll_stop(struct vhost_net *net)
 112 {
 113         if (likely(net->tx_poll_state != VHOST_NET_POLL_STARTED))
 114                 return;
 115         vhost_poll_stop(net->poll + VHOST_NET_VQ_TX);
 116         net->tx_poll_state = VHOST_NET_POLL_STOPPED;
 117 }
 118
 119 /* Caller must have TX VQ lock */
 120 static void tx_poll_start(struct vhost_net *net, struct socket *sock)
 121 {
 122         if (unlikely(net->tx_poll_state != VHOST_NET_POLL_STOPPED))
 123                 return;
 124         vhost_poll_start(net->poll + VHOST_NET_VQ_TX, sock->file);
 125         net->tx_poll_state = VHOST_NET_POLL_STARTED;
 126 }
 127
 128 /* Expects to be always run from workqueue - which acts as
 129  * read-size critical section for our kind of RCU. */
 130 static void handle_tx(struct vhost_net *net)
 131 {
 132         struct vhost_virtqueue *vq = &net->dev.vqs[VHOST_NET_VQ_TX];
 133         unsigned out, in, s;
 134         int head;
 135         struct msghdr msg = {
 136                 .msg_name = NULL,
 137                 .msg_namelen = 0,
 138                 .msg_control = NULL,
 139                 .msg_controllen = 0,
 140                 .msg_iov = vq->iov,
 141                 .msg_flags = MSG_DONTWAIT,
 142         };
 143         size_t len, total_len = 0;
 144         int err, wmem;
 145         size_t hdr_size;
 146         struct socket *sock;
 147         struct vhost_ubuf_ref *uninitialized_var(ubufs);
 148         bool zcopy;
 149
 150         /* TODO: check that we are running from vhost_worker? */
 151         sock = rcu_dereference_check(vq->private_data, 1);
 152         if (!sock)
 153                 return;
 154
 155         wmem = atomic_read(&sock->sk->sk_wmem_alloc);
 156         if (wmem >= sock->sk->sk_sndbuf) {
 157                 mutex_lock(&vq->mutex);
 158                 tx_poll_start(net, sock);
 159                 mutex_unlock(&vq->mutex);
 160                 return;
 161         }
 162
 163         mutex_lock(&vq->mutex);
 164         vhost_disable_notify(&net->dev, vq);
 165
 166         if (wmem < sock->sk->sk_sndbuf / 2)
 167                 tx_poll_stop(net);
 168         hdr_size = vq->vhost_hlen;
 169         zcopy = vhost_sock_zcopy(sock);
 170
 171         for (;;) {
 172                 /* Release DMAs done buffers first */
 173                 if (zcopy)
 174                         vhost_zerocopy_signal_used(vq);
 175
 176                 head = vhost_get_vq_desc(&net->dev, vq, vq->iov,
 177                                          ARRAY_SIZE(vq->iov),
 178                                          &out, &in,
 179                                          NULL, NULL);
 180                 /* On error, stop handling until the next kick. */
 181                 if (unlikely(head < 0))
 182                         break;
 183                 /* Nothing new?  Wait for eventfd to tell us they refilled. */
 184                 if (head == vq->num) {
 185                         wmem = atomic_read(&sock->sk->sk_wmem_alloc);
 186                         if (wmem >= sock->sk->sk_sndbuf * 3 / 4) {
 187                                 tx_poll_start(net, sock);
 188                                 set_bit(SOCK_ASYNC_NOSPACE, &sock->flags);
 189                                 break;
 190                         }
 191                         /* If more outstanding DMAs, queue the work */
 192                         if (unlikely(vq->upend_idx - vq->done_idx >
 193                                      VHOST_MAX_PEND)) {
 194                                 tx_poll_start(net, sock);
 195                                 set_bit(SOCK_ASYNC_NOSPACE, &sock->flags);
 196                                 break;
 197                         }
 198                         if (unlikely(vhost_enable_notify(&net->dev, vq))) {
 199                                 vhost_disable_notify(&net->dev, vq);
 200                                 continue;
 201                         }
 202                         break;
 203                 }
 204                 if (in) {
 205                         vq_err(vq, "Unexpected descriptor format for TX: "
 206                                "out %d, int %d\n", out, in);
 207                         break;
 208                 }
 209                 /* Skip header. TODO: support TSO. */
 210                 s = move_iovec_hdr(vq->iov, vq->hdr, hdr_size, out);
 211                 msg.msg_iovlen = out;
 212                 len = iov_length(vq->iov, out);
 213                 /* Sanity check */
 214                 if (!len) {
 215                         vq_err(vq, "Unexpected header len for TX: "
 216                                "%zd expected %zd\n",
 217                                iov_length(vq->hdr, s), hdr_size);
 218                         break;
 219                 }
 220                 /* use msg_control to pass vhost zerocopy ubuf info to skb */
 221                 if (zcopy) {
 222                         vq->heads[vq->upend_idx].id = head;
 223                         if (len < VHOST_GOODCOPY_LEN) {
 224                                 /* copy don't need to wait for DMA done */
 225                                 vq->heads[vq->upend_idx].len =
 226                                                         VHOST_DMA_DONE_LEN;
 227                                 msg.msg_control = NULL;
 228                                 msg.msg_controllen = 0;
 229                                 ubufs = NULL;
 230                         } else {
 231                                 struct ubuf_info *ubuf = &vq->ubuf_info[head];
 232
 233                                 vq->heads[vq->upend_idx].len = len;
 234                                 ubuf->callback = vhost_zerocopy_callback;
 235                                 ubuf->arg = vq->ubufs;
 236                                 ubuf->desc = vq->upend_idx;
 237                                 msg.msg_control = ubuf;
 238                                 msg.msg_controllen = sizeof(ubuf);
 239                                 ubufs = vq->ubufs;
 240                                 kref_get(&ubufs->kref);
 241                         }
 242                         vq->upend_idx = (vq->upend_idx + 1) % UIO_MAXIOV;
 243                 }
 244                 /* TODO: Check specific error and bomb out unless ENOBUFS? */
 245                 err = sock->ops->sendmsg(NULL, sock, &msg, len);
 246                 if (unlikely(err < 0)) {
 247                         if (zcopy) {
 248                                 if (ubufs)
 249                                         vhost_ubuf_put(ubufs);
 250                                 vq->upend_idx = ((unsigned)vq->upend_idx - 1) %
 251                                         UIO_MAXIOV;
 252                         }
 253                         vhost_discard_vq_desc(vq, 1);
 254                         tx_poll_start(net, sock);
 255                         break;
 256                 }
 257                 if (err != len)
 258                         pr_debug("Truncated TX packet: "
 259                                  " len %d != %zd\n", err, len);
 260                 if (!zcopy)
 261                         vhost_add_used_and_signal(&net->dev, vq, head, 0);
 262                 total_len += len;
 263                 if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
 264                         vhost_poll_queue(&vq->poll);
 265                         break;
 266                 }
 267         }
 268
 269         mutex_unlock(&vq->mutex);
 270 }
 271
 272 static int peek_head_len(struct sock *sk)
 273 {
 274         struct sk_buff *head;
 275         int len = 0;
 276         unsigned long flags;
 277
 278         spin_lock_irqsave(&sk->sk_receive_queue.lock, flags);
 279         head = skb_peek(&sk->sk_receive_queue);
 280         if (likely(head))
 281                 len = head->len;
 282         spin_unlock_irqrestore(&sk->sk_receive_queue.lock, flags);
 283         return len;
 284 }
 285
 286 /* This is a multi-buffer version of vhost_get_desc, that works if
 287  *      vq has read descriptors only.
 288  * @vq          - the relevant virtqueue
 289  * @datalen     - data length we'll be reading
 290  * @iovcount    - returned count of io vectors we fill
 291  * @log         - vhost log
 292  * @log_num     - log offset
 293  * @quota       - headcount quota, 1 for big buffer
 294  *      returns number of buffer heads allocated, negative on error
 295  */
 296 static int get_rx_bufs(struct vhost_virtqueue *vq,
 297                        struct vring_used_elem *heads,
 298                        int datalen,
 299                        unsigned *iovcount,
 300                        struct vhost_log *log,
 301                        unsigned *log_num,
 302                        unsigned int quota)
 303 {
 304         unsigned int out, in;
 305         int seg = 0;
 306         int headcount = 0;
 307         unsigned d;
 308         int r, nlogs = 0;
 309
 310         while (datalen > 0 && headcount < quota) {
 311                 if (unlikely(seg >= UIO_MAXIOV)) {
 312                         r = -ENOBUFS;
 313                         goto err;
 314                 }
 315                 d = vhost_get_vq_desc(vq->dev, vq, vq->iov + seg,
 316                                       ARRAY_SIZE(vq->iov) - seg, &out,
 317                                       &in, log, log_num);
 318                 if (d == vq->num) {
 319                         r = 0;
 320                         goto err;
 321                 }
 322                 if (unlikely(out || in <= 0)) {
 323                         vq_err(vq, "unexpected descriptor format for RX: "
 324                                 "out %d, in %d\n", out, in);
 325                         r = -EINVAL;
 326                         goto err;
 327                 }
 328                 if (unlikely(log)) {
 329                         nlogs += *log_num;
 330                         log += *log_num;
 331                 }
 332                 heads[headcount].id = d;
 333                 heads[headcount].len = iov_length(vq->iov + seg, in);
 334                 datalen -= heads[headcount].len;
 335                 ++headcount;
 336                 seg += in;
 337         }
 338         heads[headcount - 1].len += datalen;
 339         *iovcount = seg;
 340         if (unlikely(log))
 341                 *log_num = nlogs;
 342         return headcount;
 343 err:
 344         vhost_discard_vq_desc(vq, headcount);
 345         return r;
 346 }
 347
 348 /* Expects to be always run from workqueue - which acts as
 349  * read-size critical section for our kind of RCU. */
 350 static void handle_rx(struct vhost_net *net)
 351 {
 352         struct vhost_virtqueue *vq = &net->dev.vqs[VHOST_NET_VQ_RX];
 353         unsigned uninitialized_var(in), log;
 354         struct vhost_log *vq_log;
 355         struct msghdr msg = {
 356                 .msg_name = NULL,
 357                 .msg_namelen = 0,
 358                 .msg_control = NULL, /* FIXME: get and handle RX aux data. */
 359                 .msg_controllen = 0,
 360                 .msg_iov = vq->iov,
 361                 .msg_flags = MSG_DONTWAIT,
 362         };
 363         struct virtio_net_hdr_mrg_rxbuf hdr = {
 364                 .hdr.flags = 0,
 365                 .hdr.gso_type = VIRTIO_NET_HDR_GSO_NONE
 366         };
 367         size_t total_len = 0;
 368         int err, headcount, mergeable;
 369         size_t vhost_hlen, sock_hlen;
 370         size_t vhost_len, sock_len;
 371         /* TODO: check that we are running from vhost_worker? */
 372         struct socket *sock = rcu_dereference_check(vq->private_data, 1);
 373
 374         if (!sock)
 375                 return;
 376
 377         mutex_lock(&vq->mutex);
 378         vhost_disable_notify(&net->dev, vq);
 379         vhost_hlen = vq->vhost_hlen;
 380         sock_hlen = vq->sock_hlen;
 381
 382         vq_log = unlikely(vhost_has_feature(&net->dev, VHOST_F_LOG_ALL)) ?
 383                 vq->log : NULL;
 384         mergeable = vhost_has_feature(&net->dev, VIRTIO_NET_F_MRG_RXBUF);
 385
 386         while ((sock_len = peek_head_len(sock->sk))) {
 387                 sock_len += sock_hlen;
 388                 vhost_len = sock_len + vhost_hlen;
 389                 headcount = get_rx_bufs(vq, vq->heads, vhost_len,
 390                                         &in, vq_log, &log,
 391                                         likely(mergeable) ? UIO_MAXIOV : 1);
 392                 /* On error, stop handling until the next kick. */
 393                 if (unlikely(headcount < 0))
 394                         break;
 395                 /* OK, now we need to know about added descriptors. */
 396                 if (!headcount) {
 397                         if (unlikely(vhost_enable_notify(&net->dev, vq))) {
 398                                 /* They have slipped one in as we were
 399                                  * doing that: check again. */
 400                                 vhost_disable_notify(&net->dev, vq);
 401                                 continue;
 402                         }
 403                         /* Nothing new?  Wait for eventfd to tell us
 404                          * they refilled. */
 405                         break;
 406                 }
 407                 /* We don't need to be notified again. */
 408                 if (unlikely((vhost_hlen)))
 409                         /* Skip header. TODO: support TSO. */
 410                         move_iovec_hdr(vq->iov, vq->hdr, vhost_hlen, in);
 411                 else
 412                         /* Copy the header for use in VIRTIO_NET_F_MRG_RXBUF:
 413                          * needed because recvmsg can modify msg_iov. */
 414                         copy_iovec_hdr(vq->iov, vq->hdr, sock_hlen, in);
 415                 msg.msg_iovlen = in;
 416                 err = sock->ops->recvmsg(NULL, sock, &msg,
 417                                          sock_len, MSG_DONTWAIT | MSG_TRUNC);
 418                 /* Userspace might have consumed the packet meanwhile:
 419                  * it's not supposed to do this usually, but might be hard
 420                  * to prevent. Discard data we got (if any) and keep going. */
 421                 if (unlikely(err != sock_len)) {
 422                         pr_debug("Discarded rx packet: "
 423                                  " len %d, expected %zd\n", err, sock_len);
 424                         vhost_discard_vq_desc(vq, headcount);
 425                         continue;
 426                 }
 427                 if (unlikely(vhost_hlen) &&
 428                     memcpy_toiovecend(vq->hdr, (unsigned char *)&hdr, 0,
 429                                       vhost_hlen)) {
 430                         vq_err(vq, "Unable to write vnet_hdr at addr %p\n",
 431                                vq->iov->iov_base);
 432                         break;
 433                 }
 434                 /* TODO: Should check and handle checksum. */
 435                 if (likely(mergeable) &&
 436                     memcpy_toiovecend(vq->hdr, (unsigned char *)&headcount,
 437                                       offsetof(typeof(hdr), num_buffers),
 438                                       sizeof hdr.num_buffers)) {
 439                         vq_err(vq, "Failed num_buffers write");
 440                         vhost_discard_vq_desc(vq, headcount);
 441                         break;
 442                 }
 443                 vhost_add_used_and_signal_n(&net->dev, vq, vq->heads,
 444                                             headcount);
 445                 if (unlikely(vq_log))
 446                         vhost_log_write(vq, vq_log, log, vhost_len);
 447                 total_len += vhost_len;
 448                 if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
 449                         vhost_poll_queue(&vq->poll);
 450                         break;
 451                 }
 452         }
 453
 454         mutex_unlock(&vq->mutex);
 455 }
 456
 457 static void handle_tx_kick(struct vhost_work *work)
 458 {
 459         struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
 460                                                   poll.work);
 461         struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev);
 462
 463         handle_tx(net);
 464 }
 465
 466 static void handle_rx_kick(struct vhost_work *work)
 467 {
 468         struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
 469                                                   poll.work);
 470         struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev);
 471
 472         handle_rx(net);
 473 }
 474
 475 static void handle_tx_net(struct vhost_work *work)
 476 {
 477         struct vhost_net *net = container_of(work, struct vhost_net,
 478                                              poll[VHOST_NET_VQ_TX].work);
 479         handle_tx(net);
 480 }
 481
 482 static void handle_rx_net(struct vhost_work *work)
 483 {
 484         struct vhost_net *net = container_of(work, struct vhost_net,
 485                                              poll[VHOST_NET_VQ_RX].work);
 486         handle_rx(net);
 487 }
 488
 489 static int vhost_net_open(struct inode *inode, struct file *f)
 490 {
 491         struct vhost_net *n = kmalloc(sizeof *n, GFP_KERNEL);
 492         struct vhost_dev *dev;
 493         int r;
 494
 495         if (!n)
 496                 return -ENOMEM;
 497
 498         dev = &n->dev;
 499         n->vqs[VHOST_NET_VQ_TX].handle_kick = handle_tx_kick;
 500         n->vqs[VHOST_NET_VQ_RX].handle_kick = handle_rx_kick;
 501         r = vhost_dev_init(dev, n->vqs, VHOST_NET_VQ_MAX);
 502         if (r < 0) {
 503                 kfree(n);
 504                 return r;
 505         }
 506
 507         vhost_poll_init(n->poll + VHOST_NET_VQ_TX, handle_tx_net, POLLOUT, dev);
 508         vhost_poll_init(n->poll + VHOST_NET_VQ_RX, handle_rx_net, POLLIN, dev);
 509         n->tx_poll_state = VHOST_NET_POLL_DISABLED;
 510
 511         f->private_data = n;
 512
 513         return 0;
 514 }
 515
 516 static void vhost_net_disable_vq(struct vhost_net *n,
 517                                  struct vhost_virtqueue *vq)
 518 {
 519         if (!vq->private_data)
 520                 return;
 521         if (vq == n->vqs + VHOST_NET_VQ_TX) {
 522                 tx_poll_stop(n);
 523                 n->tx_poll_state = VHOST_NET_POLL_DISABLED;
 524         } else
 525                 vhost_poll_stop(n->poll + VHOST_NET_VQ_RX);
 526 }
 527
 528 static void vhost_net_enable_vq(struct vhost_net *n,
 529                                 struct vhost_virtqueue *vq)
 530 {
 531         struct socket *sock;
 532
 533         sock = rcu_dereference_protected(vq->private_data,
 534                                          lockdep_is_held(&vq->mutex));
 535         if (!sock)
 536                 return;
 537         if (vq == n->vqs + VHOST_NET_VQ_TX) {
 538                 n->tx_poll_state = VHOST_NET_POLL_STOPPED;
 539                 tx_poll_start(n, sock);
 540         } else
 541                 vhost_poll_start(n->poll + VHOST_NET_VQ_RX, sock->file);
 542 }
 543
 544 static struct socket *vhost_net_stop_vq(struct vhost_net *n,
 545                                         struct vhost_virtqueue *vq)
 546 {
 547         struct socket *sock;
 548
 549         mutex_lock(&vq->mutex);
 550         sock = rcu_dereference_protected(vq->private_data,
 551                                          lockdep_is_held(&vq->mutex));
 552         vhost_net_disable_vq(n, vq);
 553         rcu_assign_pointer(vq->private_data, NULL);
 554         mutex_unlock(&vq->mutex);
 555         return sock;
 556 }
 557
 558 static void vhost_net_stop(struct vhost_net *n, struct socket **tx_sock,
 559                            struct socket **rx_sock)
 560 {
 561         *tx_sock = vhost_net_stop_vq(n, n->vqs + VHOST_NET_VQ_TX);
 562         *rx_sock = vhost_net_stop_vq(n, n->vqs + VHOST_NET_VQ_RX);
 563 }
 564
 565 static void vhost_net_flush_vq(struct vhost_net *n, int index)
 566 {
 567         vhost_poll_flush(n->poll + index);
 568         vhost_poll_flush(&n->dev.vqs[index].poll);
 569 }
 570
 571 static void vhost_net_flush(struct vhost_net *n)
 572 {
 573         vhost_net_flush_vq(n, VHOST_NET_VQ_TX);
 574         vhost_net_flush_vq(n, VHOST_NET_VQ_RX);
 575 }
 576
 577 static int vhost_net_release(struct inode *inode, struct file *f)
 578 {
 579         struct vhost_net *n = f->private_data;
 580         struct socket *tx_sock;
 581         struct socket *rx_sock;
 582
 583         vhost_net_stop(n, &tx_sock, &rx_sock);
 584         vhost_net_flush(n);
 585         vhost_dev_cleanup(&n->dev);
 586         if (tx_sock)
 587                 fput(tx_sock->file);
 588         if (rx_sock)
 589                 fput(rx_sock->file);
 590         /* We do an extra flush before freeing memory,
 591          * since jobs can re-queue themselves. */
 592         vhost_net_flush(n);
 593         kfree(n);
 594         return 0;
 595 }
 596
 597 static struct socket *get_raw_socket(int fd)
 598 {
 599         struct {
 600                 struct sockaddr_ll sa;
 601                 char  buf[MAX_ADDR_LEN];
 602         } uaddr;
 603         int uaddr_len = sizeof uaddr, r;
 604         struct socket *sock = sockfd_lookup(fd, &r);
 605
 606         if (!sock)
 607                 return ERR_PTR(-ENOTSOCK);
 608
 609         /* Parameter checking */
 610         if (sock->sk->sk_type != SOCK_RAW) {
 611                 r = -ESOCKTNOSUPPORT;
 612                 goto err;
 613         }
 614
 615         r = sock->ops->getname(sock, (struct sockaddr *)&uaddr.sa,
 616                                &uaddr_len, 0);
 617         if (r)
 618                 goto err;
 619
 620         if (uaddr.sa.sll_family != AF_PACKET) {
 621                 r = -EPFNOSUPPORT;
 622                 goto err;
 623         }
 624         return sock;
 625 err:
 626         fput(sock->file);
 627         return ERR_PTR(r);
 628 }
 629
 630 static struct socket *get_tap_socket(int fd)
 631 {
 632         struct file *file = fget(fd);
 633         struct socket *sock;
 634
 635         if (!file)
 636                 return ERR_PTR(-EBADF);
 637         sock = tun_get_socket(file);
 638         if (!IS_ERR(sock))
 639                 return sock;
 640         sock = macvtap_get_socket(file);
 641         if (IS_ERR(sock))
 642                 fput(file);
 643         return sock;
 644 }
 645
 646 static struct socket *get_socket(int fd)
 647 {
 648         struct socket *sock;
 649
 650         /* special case to disable backend */
 651         if (fd == -1)
 652                 return NULL;
 653         sock = get_raw_socket(fd);
 654         if (!IS_ERR(sock))
 655                 return sock;
 656         sock = get_tap_socket(fd);
 657         if (!IS_ERR(sock))
 658                 return sock;
 659         return ERR_PTR(-ENOTSOCK);
 660 }
 661
 662 static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
 663 {
 664         struct socket *sock, *oldsock;
 665         struct vhost_virtqueue *vq;
 666         struct vhost_ubuf_ref *ubufs, *oldubufs = NULL;
 667         int r;
 668
 669         mutex_lock(&n->dev.mutex);
 670         r = vhost_dev_check_owner(&n->dev);
 671         if (r)
 672                 goto err;
 673
 674         if (index >= VHOST_NET_VQ_MAX) {
 675                 r = -ENOBUFS;
 676                 goto err;
 677         }
 678         vq = n->vqs + index;
 679         mutex_lock(&vq->mutex);
 680
 681         /* Verify that ring has been setup correctly. */
 682         if (!vhost_vq_access_ok(vq)) {
 683                 r = -EFAULT;
 684                 goto err_vq;
 685         }
 686         sock = get_socket(fd);
 687         if (IS_ERR(sock)) {
 688                 r = PTR_ERR(sock);
 689                 goto err_vq;
 690         }
 691
 692         /* start polling new socket */
 693         oldsock = rcu_dereference_protected(vq->private_data,
 694                                             lockdep_is_held(&vq->mutex));
 695         if (sock != oldsock) {
 696                 ubufs = vhost_ubuf_alloc(vq, sock && vhost_sock_zcopy(sock));
 697                 if (IS_ERR(ubufs)) {
 698                         r = PTR_ERR(ubufs);
 699                         goto err_ubufs;
 700                 }
 701                 oldubufs = vq->ubufs;
 702                 vq->ubufs = ubufs;
 703                 vhost_net_disable_vq(n, vq);
 704                 rcu_assign_pointer(vq->private_data, sock);
 705                 vhost_net_enable_vq(n, vq);
 706         }
 707
 708         mutex_unlock(&vq->mutex);
 709
 710         if (oldubufs)
 711                 vhost_ubuf_put_and_wait(oldubufs);
 712
 713         if (oldsock) {
 714                 vhost_net_flush_vq(n, index);
 715                 fput(oldsock->file);
 716         }
 717
 718         mutex_unlock(&n->dev.mutex);
 719         return 0;
 720
 721 err_ubufs:
 722         fput(sock->file);
 723 err_vq:
 724         mutex_unlock(&vq->mutex);
 725 err:
 726         mutex_unlock(&n->dev.mutex);
 727         return r;
 728 }
 729
 730 static long vhost_net_reset_owner(struct vhost_net *n)
 731 {
 732         struct socket *tx_sock = NULL;
 733         struct socket *rx_sock = NULL;
 734         long err;
 735
 736         mutex_lock(&n->dev.mutex);
 737         err = vhost_dev_check_owner(&n->dev);
 738         if (err)
 739                 goto done;
 740         vhost_net_stop(n, &tx_sock, &rx_sock);
 741         vhost_net_flush(n);
 742         err = vhost_dev_reset_owner(&n->dev);
 743 done:
 744         mutex_unlock(&n->dev.mutex);
 745         if (tx_sock)
 746                 fput(tx_sock->file);
 747         if (rx_sock)
 748                 fput(rx_sock->file);
 749         return err;
 750 }
 751
 752 static int vhost_net_set_features(struct vhost_net *n, u64 features)
 753 {
 754         size_t vhost_hlen, sock_hlen, hdr_len;
 755         int i;
 756
 757         hdr_len = (features & (1 << VIRTIO_NET_F_MRG_RXBUF)) ?
 758                         sizeof(struct virtio_net_hdr_mrg_rxbuf) :
 759                         sizeof(struct virtio_net_hdr);
 760         if (features & (1 << VHOST_NET_F_VIRTIO_NET_HDR)) {
 761                 /* vhost provides vnet_hdr */
 762                 vhost_hlen = hdr_len;
 763                 sock_hlen = 0;
 764         } else {
 765                 /* socket provides vnet_hdr */
 766                 vhost_hlen = 0;
 767                 sock_hlen = hdr_len;
 768         }
 769         mutex_lock(&n->dev.mutex);
 770         if ((features & (1 << VHOST_F_LOG_ALL)) &&
 771             !vhost_log_access_ok(&n->dev)) {
 772                 mutex_unlock(&n->dev.mutex);
 773                 return -EFAULT;
 774         }
 775         n->dev.acked_features = features;
 776         smp_wmb();
 777         for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
 778                 mutex_lock(&n->vqs[i].mutex);
 779                 n->vqs[i].vhost_hlen = vhost_hlen;
 780                 n->vqs[i].sock_hlen = sock_hlen;
 781                 mutex_unlock(&n->vqs[i].mutex);
 782         }
 783         vhost_net_flush(n);
 784         mutex_unlock(&n->dev.mutex);
 785         return 0;
 786 }
 787
 788 static long vhost_net_ioctl(struct file *f, unsigned int ioctl,
 789                             unsigned long arg)
 790 {
 791         struct vhost_net *n = f->private_data;
 792         void __user *argp = (void __user *)arg;
 793         u64 __user *featurep = argp;
 794         struct vhost_vring_file backend;
 795         u64 features;
 796         int r;
 797
 798         switch (ioctl) {
 799         case VHOST_NET_SET_BACKEND:
 800                 if (copy_from_user(&backend, argp, sizeof backend))
 801                         return -EFAULT;
 802                 return vhost_net_set_backend(n, backend.index, backend.fd);
 803         case VHOST_GET_FEATURES:
 804                 features = VHOST_FEATURES;
 805                 if (copy_to_user(featurep, &features, sizeof features))
 806                         return -EFAULT;
 807                 return 0;
 808         case VHOST_SET_FEATURES:
 809                 if (copy_from_user(&features, featurep, sizeof features))
 810                         return -EFAULT;
 811                 if (features & ~VHOST_FEATURES)
 812                         return -EOPNOTSUPP;
 813                 return vhost_net_set_features(n, features);
 814         case VHOST_RESET_OWNER:
 815                 return vhost_net_reset_owner(n);
 816         default:
 817                 mutex_lock(&n->dev.mutex);
 818                 r = vhost_dev_ioctl(&n->dev, ioctl, arg);
 819                 vhost_net_flush(n);
 820                 mutex_unlock(&n->dev.mutex);
 821                 return r;
 822         }
 823 }
 824
 825 #ifdef CONFIG_COMPAT
 826 static long vhost_net_compat_ioctl(struct file *f, unsigned int ioctl,
 827                                    unsigned long arg)
 828 {
 829         return vhost_net_ioctl(f, ioctl, (unsigned long)compat_ptr(arg));
 830 }
 831 #endif
 832
 833 static const struct file_operations vhost_net_fops = {
 834         .owner          = THIS_MODULE,
 835         .release        = vhost_net_release,
 836         .unlocked_ioctl = vhost_net_ioctl,
 837 #ifdef CONFIG_COMPAT
 838         .compat_ioctl   = vhost_net_compat_ioctl,
 839 #endif
 840         .open           = vhost_net_open,
 841         .llseek         = noop_llseek,
 842 };
 843
 844 static struct miscdevice vhost_net_misc = {
 845         MISC_DYNAMIC_MINOR,
 846         "vhost-net",
 847         &vhost_net_fops,
 848 };
 849
 850 static int vhost_net_init(void)
 851 {
 852         if (experimental_zcopytx)
 853                 vhost_enable_zcopy(VHOST_NET_VQ_TX);
 854         return misc_register(&vhost_net_misc);
 855 }
 856 module_init(vhost_net_init);
 857
 858 static void vhost_net_exit(void)
 859 {
 860         misc_deregister(&vhost_net_misc);
 861 }
 862 module_exit(vhost_net_exit);
 863
 864 MODULE_VERSION("0.0.1");
 865 MODULE_LICENSE("GPL v2");
 866 MODULE_AUTHOR("Michael S. Tsirkin");
 867 MODULE_DESCRIPTION("Host kernel accelerator for virtio net");