drivers/vhost/net.c

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