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                         int num_pends;
 186
 187                         wmem = atomic_read(&sock->sk->sk_wmem_alloc);
 188                         if (wmem >= sock->sk->sk_sndbuf * 3 / 4) {
 189                                 tx_poll_start(net, sock);
 190                                 set_bit(SOCK_ASYNC_NOSPACE, &sock->flags);
 191                                 break;
 192                         }
 193                         /* If more outstanding DMAs, queue the work.
 194                          * Handle upend_idx wrap around
 195                          */
 196                         num_pends = likely(vq->upend_idx >= vq->done_idx) ?
 197                                     (vq->upend_idx - vq->done_idx) :
 198                                     (vq->upend_idx + UIO_MAXIOV - vq->done_idx);
 199                         if (unlikely(num_pends > VHOST_MAX_PEND)) {
 200                                 tx_poll_start(net, sock);
 201                                 set_bit(SOCK_ASYNC_NOSPACE, &sock->flags);
 202                                 break;
 203                         }
 204                         if (unlikely(vhost_enable_notify(&net->dev, vq))) {
 205                                 vhost_disable_notify(&net->dev, vq);
 206                                 continue;
 207                         }
 208                         break;
 209                 }
 210                 if (in) {
 211                         vq_err(vq, "Unexpected descriptor format for TX: "
 212                                "out %d, int %d\n", out, in);
 213                         break;
 214                 }
 215                 /* Skip header. TODO: support TSO. */
 216                 s = move_iovec_hdr(vq->iov, vq->hdr, hdr_size, out);
 217                 msg.msg_iovlen = out;
 218                 len = iov_length(vq->iov, out);
 219                 /* Sanity check */
 220                 if (!len) {
 221                         vq_err(vq, "Unexpected header len for TX: "
 222                                "%zd expected %zd\n",
 223                                iov_length(vq->hdr, s), hdr_size);
 224                         break;
 225                 }
 226                 /* use msg_control to pass vhost zerocopy ubuf info to skb */
 227                 if (zcopy) {
 228                         vq->heads[vq->upend_idx].id = head;
 229                         if (len < VHOST_GOODCOPY_LEN) {
 230                                 /* copy don't need to wait for DMA done */
 231                                 vq->heads[vq->upend_idx].len =
 232                                                         VHOST_DMA_DONE_LEN;
 233                                 msg.msg_control = NULL;
 234                                 msg.msg_controllen = 0;
 235                                 ubufs = NULL;
 236                         } else {
 237                                 struct ubuf_info *ubuf;
 238                                 ubuf = vq->ubuf_info + vq->upend_idx;
 239
 240                                 vq->heads[vq->upend_idx].len = len;
 241                                 ubuf->callback = vhost_zerocopy_callback;
 242                                 ubuf->arg = vq->ubufs;
 243                                 ubuf->desc = vq->upend_idx;
 244                                 msg.msg_control = ubuf;
 245                                 msg.msg_controllen = sizeof(ubuf);
 246                                 ubufs = vq->ubufs;
 247                                 kref_get(&ubufs->kref);
 248                         }
 249                         vq->upend_idx = (vq->upend_idx + 1) % UIO_MAXIOV;
 250                 }
 251                 /* TODO: Check specific error and bomb out unless ENOBUFS? */
 252                 err = sock->ops->sendmsg(NULL, sock, &msg, len);
 253                 if (unlikely(err < 0)) {
 254                         if (zcopy) {
 255                                 if (ubufs)
 256                                         vhost_ubuf_put(ubufs);
 257                                 vq->upend_idx = ((unsigned)vq->upend_idx - 1) %
 258                                         UIO_MAXIOV;
 259                         }
 260                         vhost_discard_vq_desc(vq, 1);
 261                         tx_poll_start(net, sock);
 262                         break;
 263                 }
 264                 if (err != len)
 265                         pr_debug("Truncated TX packet: "
 266                                  " len %d != %zd\n", err, len);
 267                 if (!zcopy)
 268                         vhost_add_used_and_signal(&net->dev, vq, head, 0);
 269                 total_len += len;
 270                 if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
 271                         vhost_poll_queue(&vq->poll);
 272                         break;
 273                 }
 274         }
 275
 276         mutex_unlock(&vq->mutex);
 277 }
 278
 279 static int peek_head_len(struct sock *sk)
 280 {
 281         struct sk_buff *head;
 282         int len = 0;
 283         unsigned long flags;
 284
 285         spin_lock_irqsave(&sk->sk_receive_queue.lock, flags);
 286         head = skb_peek(&sk->sk_receive_queue);
 287         if (likely(head))
 288                 len = head->len;
 289         spin_unlock_irqrestore(&sk->sk_receive_queue.lock, flags);
 290         return len;
 291 }
 292
 293 /* This is a multi-buffer version of vhost_get_desc, that works if
 294  *      vq has read descriptors only.
 295  * @vq          - the relevant virtqueue
 296  * @datalen     - data length we'll be reading
 297  * @iovcount    - returned count of io vectors we fill
 298  * @log         - vhost log
 299  * @log_num     - log offset
 300  * @quota       - headcount quota, 1 for big buffer
 301  *      returns number of buffer heads allocated, negative on error
 302  */
 303 static int get_rx_bufs(struct vhost_virtqueue *vq,
 304                        struct vring_used_elem *heads,
 305                        int datalen,
 306                        unsigned *iovcount,
 307                        struct vhost_log *log,
 308                        unsigned *log_num,
 309                        unsigned int quota)
 310 {
 311         unsigned int out, in;
 312         int seg = 0;
 313         int headcount = 0;
 314         unsigned d;
 315         int r, nlogs = 0;
 316
 317         while (datalen > 0 && headcount < quota) {
 318                 if (unlikely(seg >= UIO_MAXIOV)) {
 319                         r = -ENOBUFS;
 320                         goto err;
 321                 }
 322                 r = vhost_get_vq_desc(vq->dev, vq, vq->iov + seg,
 323                                       ARRAY_SIZE(vq->iov) - seg, &out,
 324                                       &in, log, log_num);
 325                 if (unlikely(r < 0))
 326                         goto err;
 327
 328                 d = r;
 329                 if (d == vq->num) {
 330                         r = 0;
 331                         goto err;
 332                 }
 333                 if (unlikely(out || in <= 0)) {
 334                         vq_err(vq, "unexpected descriptor format for RX: "
 335                                 "out %d, in %d\n", out, in);
 336                         r = -EINVAL;
 337                         goto err;
 338                 }
 339                 if (unlikely(log)) {
 340                         nlogs += *log_num;
 341                         log += *log_num;
 342                 }
 343                 heads[headcount].id = d;
 344                 heads[headcount].len = iov_length(vq->iov + seg, in);
 345                 datalen -= heads[headcount].len;
 346                 ++headcount;
 347                 seg += in;
 348         }
 349         heads[headcount - 1].len += datalen;
 350         *iovcount = seg;
 351         if (unlikely(log))
 352                 *log_num = nlogs;
 353
 354         /* Detect overrun */
 355         if (unlikely(datalen > 0)) {
 356                 r = UIO_MAXIOV + 1;
 357                 goto err;
 358         }
 359         return headcount;
 360 err:
 361         vhost_discard_vq_desc(vq, headcount);
 362         return r;
 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_rx(struct vhost_net *net)
 368 {
 369         struct vhost_virtqueue *vq = &net->dev.vqs[VHOST_NET_VQ_RX];
 370         unsigned uninitialized_var(in), log;
 371         struct vhost_log *vq_log;
 372         struct msghdr msg = {
 373                 .msg_name = NULL,
 374                 .msg_namelen = 0,
 375                 .msg_control = NULL, /* FIXME: get and handle RX aux data. */
 376                 .msg_controllen = 0,
 377                 .msg_iov = vq->iov,
 378                 .msg_flags = MSG_DONTWAIT,
 379         };
 380         struct virtio_net_hdr_mrg_rxbuf hdr = {
 381                 .hdr.flags = 0,
 382                 .hdr.gso_type = VIRTIO_NET_HDR_GSO_NONE
 383         };
 384         size_t total_len = 0;
 385         int err, mergeable;
 386         s16 headcount;
 387         size_t vhost_hlen, sock_hlen;
 388         size_t vhost_len, sock_len;
 389         /* TODO: check that we are running from vhost_worker? */
 390         struct socket *sock = rcu_dereference_check(vq->private_data, 1);
 391
 392         if (!sock)
 393                 return;
 394
 395         mutex_lock(&vq->mutex);
 396         vhost_disable_notify(&net->dev, vq);
 397         vhost_hlen = vq->vhost_hlen;
 398         sock_hlen = vq->sock_hlen;
 399
 400         vq_log = unlikely(vhost_has_feature(&net->dev, VHOST_F_LOG_ALL)) ?
 401                 vq->log : NULL;
 402         mergeable = vhost_has_feature(&net->dev, VIRTIO_NET_F_MRG_RXBUF);
 403
 404         while ((sock_len = peek_head_len(sock->sk))) {
 405                 sock_len += sock_hlen;
 406                 vhost_len = sock_len + vhost_hlen;
 407                 headcount = get_rx_bufs(vq, vq->heads, vhost_len,
 408                                         &in, vq_log, &log,
 409                                         likely(mergeable) ? UIO_MAXIOV : 1);
 410                 /* On error, stop handling until the next kick. */
 411                 if (unlikely(headcount < 0))
 412                         break;
 413                 /* On overrun, truncate and discard */
 414                 if (unlikely(headcount > UIO_MAXIOV)) {
 415                         msg.msg_iovlen = 1;
 416                         err = sock->ops->recvmsg(NULL, sock, &msg,
 417                                                  1, MSG_DONTWAIT | MSG_TRUNC);
 418                         pr_debug("Discarded rx packet: len %zd\n", sock_len);
 419                         continue;
 420                 }
 421                 /* OK, now we need to know about added descriptors. */
 422                 if (!headcount) {
 423                         if (unlikely(vhost_enable_notify(&net->dev, vq))) {
 424                                 /* They have slipped one in as we were
 425                                  * doing that: check again. */
 426                                 vhost_disable_notify(&net->dev, vq);
 427                                 continue;
 428                         }
 429                         /* Nothing new?  Wait for eventfd to tell us
 430                          * they refilled. */
 431                         break;
 432                 }
 433                 /* We don't need to be notified again. */
 434                 if (unlikely((vhost_hlen)))
 435                         /* Skip header. TODO: support TSO. */
 436                         move_iovec_hdr(vq->iov, vq->hdr, vhost_hlen, in);
 437                 else
 438                         /* Copy the header for use in VIRTIO_NET_F_MRG_RXBUF:
 439                          * needed because recvmsg can modify msg_iov. */
 440                         copy_iovec_hdr(vq->iov, vq->hdr, sock_hlen, in);
 441                 msg.msg_iovlen = in;
 442                 err = sock->ops->recvmsg(NULL, sock, &msg,
 443                                          sock_len, MSG_DONTWAIT | MSG_TRUNC);
 444                 /* Userspace might have consumed the packet meanwhile:
 445                  * it's not supposed to do this usually, but might be hard
 446                  * to prevent. Discard data we got (if any) and keep going. */
 447                 if (unlikely(err != sock_len)) {
 448                         pr_debug("Discarded rx packet: "
 449                                  " len %d, expected %zd\n", err, sock_len);
 450                         vhost_discard_vq_desc(vq, headcount);
 451                         continue;
 452                 }
 453                 if (unlikely(vhost_hlen) &&
 454                     memcpy_toiovecend(vq->hdr, (unsigned char *)&hdr, 0,
 455                                       vhost_hlen)) {
 456                         vq_err(vq, "Unable to write vnet_hdr at addr %p\n",
 457                                vq->iov->iov_base);
 458                         break;
 459                 }
 460                 /* TODO: Should check and handle checksum. */
 461                 if (likely(mergeable) &&
 462                     memcpy_toiovecend(vq->hdr, (unsigned char *)&headcount,
 463                                       offsetof(typeof(hdr), num_buffers),
 464                                       sizeof hdr.num_buffers)) {
 465                         vq_err(vq, "Failed num_buffers write");
 466                         vhost_discard_vq_desc(vq, headcount);
 467                         break;
 468                 }
 469                 vhost_add_used_and_signal_n(&net->dev, vq, vq->heads,
 470                                             headcount);
 471                 if (unlikely(vq_log))
 472                         vhost_log_write(vq, vq_log, log, vhost_len);
 473                 total_len += vhost_len;
 474                 if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
 475                         vhost_poll_queue(&vq->poll);
 476                         break;
 477                 }
 478         }
 479
 480         mutex_unlock(&vq->mutex);
 481 }
 482
 483 static void handle_tx_kick(struct vhost_work *work)
 484 {
 485         struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
 486                                                   poll.work);
 487         struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev);
 488
 489         handle_tx(net);
 490 }
 491
 492 static void handle_rx_kick(struct vhost_work *work)
 493 {
 494         struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
 495                                                   poll.work);
 496         struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev);
 497
 498         handle_rx(net);
 499 }
 500
 501 static void handle_tx_net(struct vhost_work *work)
 502 {
 503         struct vhost_net *net = container_of(work, struct vhost_net,
 504                                              poll[VHOST_NET_VQ_TX].work);
 505         handle_tx(net);
 506 }
 507
 508 static void handle_rx_net(struct vhost_work *work)
 509 {
 510         struct vhost_net *net = container_of(work, struct vhost_net,
 511                                              poll[VHOST_NET_VQ_RX].work);
 512         handle_rx(net);
 513 }
 514
 515 static int vhost_net_open(struct inode *inode, struct file *f)
 516 {
 517         struct vhost_net *n = kmalloc(sizeof *n, GFP_KERNEL);
 518         struct vhost_dev *dev;
 519         int r;
 520
 521         if (!n)
 522                 return -ENOMEM;
 523
 524         dev = &n->dev;
 525         n->vqs[VHOST_NET_VQ_TX].handle_kick = handle_tx_kick;
 526         n->vqs[VHOST_NET_VQ_RX].handle_kick = handle_rx_kick;
 527         r = vhost_dev_init(dev, n->vqs, VHOST_NET_VQ_MAX);
 528         if (r < 0) {
 529                 kfree(n);
 530                 return r;
 531         }
 532
 533         vhost_poll_init(n->poll + VHOST_NET_VQ_TX, handle_tx_net, POLLOUT, dev);
 534         vhost_poll_init(n->poll + VHOST_NET_VQ_RX, handle_rx_net, POLLIN, dev);
 535         n->tx_poll_state = VHOST_NET_POLL_DISABLED;
 536
 537         f->private_data = n;
 538
 539         return 0;
 540 }
 541
 542 static void vhost_net_disable_vq(struct vhost_net *n,
 543                                  struct vhost_virtqueue *vq)
 544 {
 545         if (!vq->private_data)
 546                 return;
 547         if (vq == n->vqs + VHOST_NET_VQ_TX) {
 548                 tx_poll_stop(n);
 549                 n->tx_poll_state = VHOST_NET_POLL_DISABLED;
 550         } else
 551                 vhost_poll_stop(n->poll + VHOST_NET_VQ_RX);
 552 }
 553
 554 static void vhost_net_enable_vq(struct vhost_net *n,
 555                                 struct vhost_virtqueue *vq)
 556 {
 557         struct socket *sock;
 558
 559         sock = rcu_dereference_protected(vq->private_data,
 560                                          lockdep_is_held(&vq->mutex));
 561         if (!sock)
 562                 return;
 563         if (vq == n->vqs + VHOST_NET_VQ_TX) {
 564                 n->tx_poll_state = VHOST_NET_POLL_STOPPED;
 565                 tx_poll_start(n, sock);
 566         } else
 567                 vhost_poll_start(n->poll + VHOST_NET_VQ_RX, sock->file);
 568 }
 569
 570 static struct socket *vhost_net_stop_vq(struct vhost_net *n,
 571                                         struct vhost_virtqueue *vq)
 572 {
 573         struct socket *sock;
 574
 575         mutex_lock(&vq->mutex);
 576         sock = rcu_dereference_protected(vq->private_data,
 577                                          lockdep_is_held(&vq->mutex));
 578         vhost_net_disable_vq(n, vq);
 579         rcu_assign_pointer(vq->private_data, NULL);
 580         mutex_unlock(&vq->mutex);
 581         return sock;
 582 }
 583
 584 static void vhost_net_stop(struct vhost_net *n, struct socket **tx_sock,
 585                            struct socket **rx_sock)
 586 {
 587         *tx_sock = vhost_net_stop_vq(n, n->vqs + VHOST_NET_VQ_TX);
 588         *rx_sock = vhost_net_stop_vq(n, n->vqs + VHOST_NET_VQ_RX);
 589 }
 590
 591 static void vhost_net_flush_vq(struct vhost_net *n, int index)
 592 {
 593         vhost_poll_flush(n->poll + index);
 594         vhost_poll_flush(&n->dev.vqs[index].poll);
 595 }
 596
 597 static void vhost_net_flush(struct vhost_net *n)
 598 {
 599         vhost_net_flush_vq(n, VHOST_NET_VQ_TX);
 600         vhost_net_flush_vq(n, VHOST_NET_VQ_RX);
 601 }
 602
 603 static int vhost_net_release(struct inode *inode, struct file *f)
 604 {
 605         struct vhost_net *n = f->private_data;
 606         struct socket *tx_sock;
 607         struct socket *rx_sock;
 608
 609         vhost_net_stop(n, &tx_sock, &rx_sock);
 610         vhost_net_flush(n);
 611         vhost_dev_cleanup(&n->dev);
 612         if (tx_sock)
 613                 fput(tx_sock->file);
 614         if (rx_sock)
 615                 fput(rx_sock->file);
 616         /* We do an extra flush before freeing memory,
 617          * since jobs can re-queue themselves. */
 618         vhost_net_flush(n);
 619         kfree(n);
 620         return 0;
 621 }
 622
 623 static struct socket *get_raw_socket(int fd)
 624 {
 625         struct {
 626                 struct sockaddr_ll sa;
 627                 char  buf[MAX_ADDR_LEN];
 628         } uaddr;
 629         int uaddr_len = sizeof uaddr, r;
 630         struct socket *sock = sockfd_lookup(fd, &r);
 631
 632         if (!sock)
 633                 return ERR_PTR(-ENOTSOCK);
 634
 635         /* Parameter checking */
 636         if (sock->sk->sk_type != SOCK_RAW) {
 637                 r = -ESOCKTNOSUPPORT;
 638                 goto err;
 639         }
 640
 641         r = sock->ops->getname(sock, (struct sockaddr *)&uaddr.sa,
 642                                &uaddr_len, 0);
 643         if (r)
 644                 goto err;
 645
 646         if (uaddr.sa.sll_family != AF_PACKET) {
 647                 r = -EPFNOSUPPORT;
 648                 goto err;
 649         }
 650         return sock;
 651 err:
 652         fput(sock->file);
 653         return ERR_PTR(r);
 654 }
 655
 656 static struct socket *get_tap_socket(int fd)
 657 {
 658         struct file *file = fget(fd);
 659         struct socket *sock;
 660
 661         if (!file)
 662                 return ERR_PTR(-EBADF);
 663         sock = tun_get_socket(file);
 664         if (!IS_ERR(sock))
 665                 return sock;
 666         sock = macvtap_get_socket(file);
 667         if (IS_ERR(sock))
 668                 fput(file);
 669         return sock;
 670 }
 671
 672 static struct socket *get_socket(int fd)
 673 {
 674         struct socket *sock;
 675
 676         /* special case to disable backend */
 677         if (fd == -1)
 678                 return NULL;
 679         sock = get_raw_socket(fd);
 680         if (!IS_ERR(sock))
 681                 return sock;
 682         sock = get_tap_socket(fd);
 683         if (!IS_ERR(sock))
 684                 return sock;
 685         return ERR_PTR(-ENOTSOCK);
 686 }
 687
 688 static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
 689 {
 690         struct socket *sock, *oldsock;
 691         struct vhost_virtqueue *vq;
 692         struct vhost_ubuf_ref *ubufs, *oldubufs = NULL;
 693         int r;
 694
 695         mutex_lock(&n->dev.mutex);
 696         r = vhost_dev_check_owner(&n->dev);
 697         if (r)
 698                 goto err;
 699
 700         if (index >= VHOST_NET_VQ_MAX) {
 701                 r = -ENOBUFS;
 702                 goto err;
 703         }
 704         vq = n->vqs + index;
 705         mutex_lock(&vq->mutex);
 706
 707         /* Verify that ring has been setup correctly. */
 708         if (!vhost_vq_access_ok(vq)) {
 709                 r = -EFAULT;
 710                 goto err_vq;
 711         }
 712         sock = get_socket(fd);
 713         if (IS_ERR(sock)) {
 714                 r = PTR_ERR(sock);
 715                 goto err_vq;
 716         }
 717
 718         /* start polling new socket */
 719         oldsock = rcu_dereference_protected(vq->private_data,
 720                                             lockdep_is_held(&vq->mutex));
 721         if (sock != oldsock) {
 722                 ubufs = vhost_ubuf_alloc(vq, sock && vhost_sock_zcopy(sock));
 723                 if (IS_ERR(ubufs)) {
 724                         r = PTR_ERR(ubufs);
 725                         goto err_ubufs;
 726                 }
 727                 oldubufs = vq->ubufs;
 728                 vq->ubufs = ubufs;
 729                 vhost_net_disable_vq(n, vq);
 730                 rcu_assign_pointer(vq->private_data, sock);
 731                 vhost_net_enable_vq(n, vq);
 732
 733                 r = vhost_init_used(vq);
 734                 if (r)
 735                         goto err_vq;
 736         }
 737
 738         mutex_unlock(&vq->mutex);
 739
 740         if (oldubufs) {
 741                 vhost_ubuf_put_and_wait(oldubufs);
 742                 mutex_lock(&vq->mutex);
 743                 vhost_zerocopy_signal_used(vq);
 744                 mutex_unlock(&vq->mutex);
 745         }
 746
 747         if (oldsock) {
 748                 vhost_net_flush_vq(n, index);
 749                 fput(oldsock->file);
 750         }
 751
 752         mutex_unlock(&n->dev.mutex);
 753         return 0;
 754
 755 err_ubufs:
 756         fput(sock->file);
 757 err_vq:
 758         mutex_unlock(&vq->mutex);
 759 err:
 760         mutex_unlock(&n->dev.mutex);
 761         return r;
 762 }
 763
 764 static long vhost_net_reset_owner(struct vhost_net *n)
 765 {
 766         struct socket *tx_sock = NULL;
 767         struct socket *rx_sock = NULL;
 768         long err;
 769
 770         mutex_lock(&n->dev.mutex);
 771         err = vhost_dev_check_owner(&n->dev);
 772         if (err)
 773                 goto done;
 774         vhost_net_stop(n, &tx_sock, &rx_sock);
 775         vhost_net_flush(n);
 776         err = vhost_dev_reset_owner(&n->dev);
 777 done:
 778         mutex_unlock(&n->dev.mutex);
 779         if (tx_sock)
 780                 fput(tx_sock->file);
 781         if (rx_sock)
 782                 fput(rx_sock->file);
 783         return err;
 784 }
 785
 786 static int vhost_net_set_features(struct vhost_net *n, u64 features)
 787 {
 788         size_t vhost_hlen, sock_hlen, hdr_len;
 789         int i;
 790
 791         hdr_len = (features & (1 << VIRTIO_NET_F_MRG_RXBUF)) ?
 792                         sizeof(struct virtio_net_hdr_mrg_rxbuf) :
 793                         sizeof(struct virtio_net_hdr);
 794         if (features & (1 << VHOST_NET_F_VIRTIO_NET_HDR)) {
 795                 /* vhost provides vnet_hdr */
 796                 vhost_hlen = hdr_len;
 797                 sock_hlen = 0;
 798         } else {
 799                 /* socket provides vnet_hdr */
 800                 vhost_hlen = 0;
 801                 sock_hlen = hdr_len;
 802         }
 803         mutex_lock(&n->dev.mutex);
 804         if ((features & (1 << VHOST_F_LOG_ALL)) &&
 805             !vhost_log_access_ok(&n->dev)) {
 806                 mutex_unlock(&n->dev.mutex);
 807                 return -EFAULT;
 808         }
 809         n->dev.acked_features = features;
 810         smp_wmb();
 811         for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
 812                 mutex_lock(&n->vqs[i].mutex);
 813                 n->vqs[i].vhost_hlen = vhost_hlen;
 814                 n->vqs[i].sock_hlen = sock_hlen;
 815                 mutex_unlock(&n->vqs[i].mutex);
 816         }
 817         vhost_net_flush(n);
 818         mutex_unlock(&n->dev.mutex);
 819         return 0;
 820 }
 821
 822 static long vhost_net_ioctl(struct file *f, unsigned int ioctl,
 823                             unsigned long arg)
 824 {
 825         struct vhost_net *n = f->private_data;
 826         void __user *argp = (void __user *)arg;
 827         u64 __user *featurep = argp;
 828         struct vhost_vring_file backend;
 829         u64 features;
 830         int r;
 831
 832         switch (ioctl) {
 833         case VHOST_NET_SET_BACKEND:
 834                 if (copy_from_user(&backend, argp, sizeof backend))
 835                         return -EFAULT;
 836                 return vhost_net_set_backend(n, backend.index, backend.fd);
 837         case VHOST_GET_FEATURES:
 838                 features = VHOST_FEATURES;
 839                 if (copy_to_user(featurep, &features, sizeof features))
 840                         return -EFAULT;
 841                 return 0;
 842         case VHOST_SET_FEATURES:
 843                 if (copy_from_user(&features, featurep, sizeof features))
 844                         return -EFAULT;
 845                 if (features & ~VHOST_FEATURES)
 846                         return -EOPNOTSUPP;
 847                 return vhost_net_set_features(n, features);
 848         case VHOST_RESET_OWNER:
 849                 return vhost_net_reset_owner(n);
 850         default:
 851                 mutex_lock(&n->dev.mutex);
 852                 r = vhost_dev_ioctl(&n->dev, ioctl, arg);
 853                 vhost_net_flush(n);
 854                 mutex_unlock(&n->dev.mutex);
 855                 return r;
 856         }
 857 }
 858
 859 #ifdef CONFIG_COMPAT
 860 static long vhost_net_compat_ioctl(struct file *f, unsigned int ioctl,
 861                                    unsigned long arg)
 862 {
 863         return vhost_net_ioctl(f, ioctl, (unsigned long)compat_ptr(arg));
 864 }
 865 #endif
 866
 867 static const struct file_operations vhost_net_fops = {
 868         .owner          = THIS_MODULE,
 869         .release        = vhost_net_release,
 870         .unlocked_ioctl = vhost_net_ioctl,
 871 #ifdef CONFIG_COMPAT
 872         .compat_ioctl   = vhost_net_compat_ioctl,
 873 #endif
 874         .open           = vhost_net_open,
 875         .llseek         = noop_llseek,
 876 };
 877
 878 static struct miscdevice vhost_net_misc = {
 879         MISC_DYNAMIC_MINOR,
 880         "vhost-net",
 881         &vhost_net_fops,
 882 };
 883
 884 static int vhost_net_init(void)
 885 {
 886         if (experimental_zcopytx)
 887                 vhost_enable_zcopy(VHOST_NET_VQ_TX);
 888         return misc_register(&vhost_net_misc);
 889 }
 890 module_init(vhost_net_init);
 891
 892 static void vhost_net_exit(void)
 893 {
 894         misc_deregister(&vhost_net_misc);
 895 }
 896 module_exit(vhost_net_exit);
 897
 898 MODULE_VERSION("0.0.1");
 899 MODULE_LICENSE("GPL v2");
 900 MODULE_AUTHOR("Michael S. Tsirkin");
 901 MODULE_DESCRIPTION("Host kernel accelerator for virtio net");