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