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