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 = &vq->ubuf_info[head];
 343
 344                                vq->heads[vq->upend_idx].len =
 345                                        VHOST_DMA_IN_PROGRESS;
 346                                ubuf->callback = vhost_zerocopy_callback;
 347                                ubuf->ctx = vq->ubufs;
 348                                ubuf->desc = vq->upend_idx;
 349                                msg.msg_control = ubuf;
 350                                msg.msg_controllen = sizeof(ubuf);
 351                                ubufs = vq->ubufs;
 352                                kref_get(&ubufs->kref);
 353                        }
 354                        vq->upend_idx = (vq->upend_idx + 1) % UIO_MAXIOV;
 355                }
 356                /* TODO: Check specific error and bomb out unless ENOBUFS? */
 357                err = sock->ops->sendmsg(NULL, sock, &msg, len);
 358                if (unlikely(err < 0)) {
 359                        if (zcopy_used) {
 360                                if (ubufs)
 361                                        vhost_ubuf_put(ubufs);
 362                                vq->upend_idx = ((unsigned)vq->upend_idx - 1) %
 363                                        UIO_MAXIOV;
 364                        }
 365                        vhost_discard_vq_desc(vq, 1);
 366                        if (err == -EAGAIN || err == -ENOBUFS)
 367                                tx_poll_start(net, sock);
 368                        break;
 369                }
 370                if (err != len)
 371                        pr_debug("Truncated TX packet: "
 372                                 " len %d != %zd\n", err, len);
 373                if (!zcopy_used)
 374                        vhost_add_used_and_signal(&net->dev, vq, head, 0);
 375                else
 376                        vhost_zerocopy_signal_used(net, vq);
 377                total_len += len;
 378                vhost_net_tx_packet(net);
 379                if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
 380                        vhost_poll_queue(&vq->poll);
 381                        break;
 382                }
 383        }
 384
 385        mutex_unlock(&vq->mutex);
 386}
 387
 388static int peek_head_len(struct sock *sk)
 389{
 390        struct sk_buff *head;
 391        int len = 0;
 392        unsigned long flags;
 393
 394        spin_lock_irqsave(&sk->sk_receive_queue.lock, flags);
 395        head = skb_peek(&sk->sk_receive_queue);
 396        if (likely(head)) {
 397                len = head->len;
 398                if (vlan_tx_tag_present(head))
 399                        len += VLAN_HLEN;
 400        }
 401
 402        spin_unlock_irqrestore(&sk->sk_receive_queue.lock, flags);
 403        return len;
 404}
 405
 406/* This is a multi-buffer version of vhost_get_desc, that works if
 407 *      vq has read descriptors only.
 408 * @vq          - the relevant virtqueue
 409 * @datalen     - data length we'll be reading
 410 * @iovcount    - returned count of io vectors we fill
 411 * @log         - vhost log
 412 * @log_num     - log offset
 413 * @quota       - headcount quota, 1 for big buffer
 414 *      returns number of buffer heads allocated, negative on error
 415 */
 416static int get_rx_bufs(struct vhost_virtqueue *vq,
 417                       struct vring_used_elem *heads,
 418                       int datalen,
 419                       unsigned *iovcount,
 420                       struct vhost_log *log,
 421                       unsigned *log_num,
 422                       unsigned int quota)
 423{
 424        unsigned int out, in;
 425        int seg = 0;
 426        int headcount = 0;
 427        unsigned d;
 428        int r, nlogs = 0;
 429
 430        while (datalen > 0 && headcount < quota) {
 431                if (unlikely(seg >= UIO_MAXIOV)) {
 432                        r = -ENOBUFS;
 433                        goto err;
 434                }
 435                d = vhost_get_vq_desc(vq->dev, vq, vq->iov + seg,
 436                                      ARRAY_SIZE(vq->iov) - seg, &out,
 437                                      &in, log, log_num);
 438                if (d == vq->num) {
 439                        r = 0;
 440                        goto err;
 441                }
 442                if (unlikely(out || in <= 0)) {
 443                        vq_err(vq, "unexpected descriptor format for RX: "
 444                                "out %d, in %d\n", out, in);
 445                        r = -EINVAL;
 446                        goto err;
 447                }
 448                if (unlikely(log)) {
 449                        nlogs += *log_num;
 450                        log += *log_num;
 451                }
 452                heads[headcount].id = d;
 453                heads[headcount].len = iov_length(vq->iov + seg, in);
 454                datalen -= heads[headcount].len;
 455                ++headcount;
 456                seg += in;
 457        }
 458        heads[headcount - 1].len += datalen;
 459        *iovcount = seg;
 460        if (unlikely(log))
 461                *log_num = nlogs;
 462        return headcount;
 463err:
 464        vhost_discard_vq_desc(vq, headcount);
 465        return r;
 466}
 467
 468/* Expects to be always run from workqueue - which acts as
 469 * read-size critical section for our kind of RCU. */
 470static void handle_rx(struct vhost_net *net)
 471{
 472        struct vhost_virtqueue *vq = &net->dev.vqs[VHOST_NET_VQ_RX];
 473        unsigned uninitialized_var(in), log;
 474        struct vhost_log *vq_log;
 475        struct msghdr msg = {
 476                .msg_name = NULL,
 477                .msg_namelen = 0,
 478                .msg_control = NULL, /* FIXME: get and handle RX aux data. */
 479                .msg_controllen = 0,
 480                .msg_iov = vq->iov,
 481                .msg_flags = MSG_DONTWAIT,
 482        };
 483        struct virtio_net_hdr_mrg_rxbuf hdr = {
 484                .hdr.flags = 0,
 485                .hdr.gso_type = VIRTIO_NET_HDR_GSO_NONE
 486        };
 487        size_t total_len = 0;
 488        int err, mergeable;
 489        s16 headcount;
 490        size_t vhost_hlen, sock_hlen;
 491        size_t vhost_len, sock_len;
 492        /* TODO: check that we are running from vhost_worker? */
 493        struct socket *sock = rcu_dereference_check(vq->private_data, 1);
 494
 495        if (!sock)
 496                return;
 497
 498        mutex_lock(&vq->mutex);
 499        vhost_disable_notify(&net->dev, vq);
 500        vhost_hlen = vq->vhost_hlen;
 501        sock_hlen = vq->sock_hlen;
 502
 503        vq_log = unlikely(vhost_has_feature(&net->dev, VHOST_F_LOG_ALL)) ?
 504                vq->log : NULL;
 505        mergeable = vhost_has_feature(&net->dev, VIRTIO_NET_F_MRG_RXBUF);
 506
 507        while ((sock_len = peek_head_len(sock->sk))) {
 508                sock_len += sock_hlen;
 509                vhost_len = sock_len + vhost_hlen;
 510                headcount = get_rx_bufs(vq, vq->heads, vhost_len,
 511                                        &in, vq_log, &log,
 512                                        likely(mergeable) ? UIO_MAXIOV : 1);
 513                /* On error, stop handling until the next kick. */
 514                if (unlikely(headcount < 0))
 515                        break;
 516                /* OK, now we need to know about added descriptors. */
 517                if (!headcount) {
 518                        if (unlikely(vhost_enable_notify(&net->dev, vq))) {
 519                                /* They have slipped one in as we were
 520                                 * doing that: check again. */
 521                                vhost_disable_notify(&net->dev, vq);
 522                                continue;
 523                        }
 524                        /* Nothing new?  Wait for eventfd to tell us
 525                         * they refilled. */
 526                        break;
 527                }
 528                /* We don't need to be notified again. */
 529                if (unlikely((vhost_hlen)))
 530                        /* Skip header. TODO: support TSO. */
 531                        move_iovec_hdr(vq->iov, vq->hdr, vhost_hlen, in);
 532                else
 533                        /* Copy the header for use in VIRTIO_NET_F_MRG_RXBUF:
 534                         * needed because recvmsg can modify msg_iov. */
 535                        copy_iovec_hdr(vq->iov, vq->hdr, sock_hlen, in);
 536                msg.msg_iovlen = in;
 537                err = sock->ops->recvmsg(NULL, sock, &msg,
 538                                         sock_len, MSG_DONTWAIT | MSG_TRUNC);
 539                /* Userspace might have consumed the packet meanwhile:
 540                 * it's not supposed to do this usually, but might be hard
 541                 * to prevent. Discard data we got (if any) and keep going. */
 542                if (unlikely(err != sock_len)) {
 543                        pr_debug("Discarded rx packet: "
 544                                 " len %d, expected %zd\n", err, sock_len);
 545                        vhost_discard_vq_desc(vq, headcount);
 546                        continue;
 547                }
 548                if (unlikely(vhost_hlen) &&
 549                    memcpy_toiovecend(vq->hdr, (unsigned char *)&hdr, 0,
 550                                      vhost_hlen)) {
 551                        vq_err(vq, "Unable to write vnet_hdr at addr %p\n",
 552                               vq->iov->iov_base);
 553                        break;
 554                }
 555                /* TODO: Should check and handle checksum. */
 556                if (likely(mergeable) &&
 557                    memcpy_toiovecend(vq->hdr, (unsigned char *)&headcount,
 558                                      offsetof(typeof(hdr), num_buffers),
 559                                      sizeof hdr.num_buffers)) {
 560                        vq_err(vq, "Failed num_buffers write");
 561                        vhost_discard_vq_desc(vq, headcount);
 562                        break;
 563                }
 564                vhost_add_used_and_signal_n(&net->dev, vq, vq->heads,
 565                                            headcount);
 566                if (unlikely(vq_log))
 567                        vhost_log_write(vq, vq_log, log, vhost_len);
 568                total_len += vhost_len;
 569                if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
 570                        vhost_poll_queue(&vq->poll);
 571                        break;
 572                }
 573        }
 574
 575        mutex_unlock(&vq->mutex);
 576}
 577
 578static void handle_tx_kick(struct vhost_work *work)
 579{
 580        struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
 581                                                  poll.work);
 582        struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev);
 583
 584        handle_tx(net);
 585}
 586
 587static void handle_rx_kick(struct vhost_work *work)
 588{
 589        struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
 590                                                  poll.work);
 591        struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev);
 592
 593        handle_rx(net);
 594}
 595
 596static void handle_tx_net(struct vhost_work *work)
 597{
 598        struct vhost_net *net = container_of(work, struct vhost_net,
 599                                             poll[VHOST_NET_VQ_TX].work);
 600        handle_tx(net);
 601}
 602
 603static void handle_rx_net(struct vhost_work *work)
 604{
 605        struct vhost_net *net = container_of(work, struct vhost_net,
 606                                             poll[VHOST_NET_VQ_RX].work);
 607        handle_rx(net);
 608}
 609
 610static int vhost_net_open(struct inode *inode, struct file *f)
 611{
 612        struct vhost_net *n = kmalloc(sizeof *n, GFP_KERNEL);
 613        struct vhost_dev *dev;
 614        int r;
 615
 616        if (!n)
 617                return -ENOMEM;
 618
 619        dev = &n->dev;
 620        n->vqs[VHOST_NET_VQ_TX].handle_kick = handle_tx_kick;
 621        n->vqs[VHOST_NET_VQ_RX].handle_kick = handle_rx_kick;
 622        r = vhost_dev_init(dev, n->vqs, VHOST_NET_VQ_MAX);
 623        if (r < 0) {
 624                kfree(n);
 625                return r;
 626        }
 627
 628        vhost_poll_init(n->poll + VHOST_NET_VQ_TX, handle_tx_net, POLLOUT, dev);
 629        vhost_poll_init(n->poll + VHOST_NET_VQ_RX, handle_rx_net, POLLIN, dev);
 630        n->tx_poll_state = VHOST_NET_POLL_DISABLED;
 631
 632        f->private_data = n;
 633
 634        return 0;
 635}
 636
 637static void vhost_net_disable_vq(struct vhost_net *n,
 638                                 struct vhost_virtqueue *vq)
 639{
 640        if (!vq->private_data)
 641                return;
 642        if (vq == n->vqs + VHOST_NET_VQ_TX) {
 643                tx_poll_stop(n);
 644                n->tx_poll_state = VHOST_NET_POLL_DISABLED;
 645        } else
 646                vhost_poll_stop(n->poll + VHOST_NET_VQ_RX);
 647}
 648
 649static int vhost_net_enable_vq(struct vhost_net *n,
 650                                struct vhost_virtqueue *vq)
 651{
 652        struct socket *sock;
 653        int ret;
 654
 655        sock = rcu_dereference_protected(vq->private_data,
 656                                         lockdep_is_held(&vq->mutex));
 657        if (!sock)
 658                return 0;
 659        if (vq == n->vqs + VHOST_NET_VQ_TX) {
 660                n->tx_poll_state = VHOST_NET_POLL_STOPPED;
 661                ret = tx_poll_start(n, sock);
 662        } else
 663                ret = vhost_poll_start(n->poll + VHOST_NET_VQ_RX, sock->file);
 664
 665        return ret;
 666}
 667
 668static struct socket *vhost_net_stop_vq(struct vhost_net *n,
 669                                        struct vhost_virtqueue *vq)
 670{
 671        struct socket *sock;
 672
 673        mutex_lock(&vq->mutex);
 674        sock = rcu_dereference_protected(vq->private_data,
 675                                         lockdep_is_held(&vq->mutex));
 676        vhost_net_disable_vq(n, vq);
 677        rcu_assign_pointer(vq->private_data, NULL);
 678        mutex_unlock(&vq->mutex);
 679        return sock;
 680}
 681
 682static void vhost_net_stop(struct vhost_net *n, struct socket **tx_sock,
 683                           struct socket **rx_sock)
 684{
 685        *tx_sock = vhost_net_stop_vq(n, n->vqs + VHOST_NET_VQ_TX);
 686        *rx_sock = vhost_net_stop_vq(n, n->vqs + VHOST_NET_VQ_RX);
 687}
 688
 689static void vhost_net_flush_vq(struct vhost_net *n, int index)
 690{
 691        vhost_poll_flush(n->poll + index);
 692        vhost_poll_flush(&n->dev.vqs[index].poll);
 693}
 694
 695static void vhost_net_flush(struct vhost_net *n)
 696{
 697        vhost_net_flush_vq(n, VHOST_NET_VQ_TX);
 698        vhost_net_flush_vq(n, VHOST_NET_VQ_RX);
 699        if (n->dev.vqs[VHOST_NET_VQ_TX].ubufs) {
 700                mutex_lock(&n->dev.vqs[VHOST_NET_VQ_TX].mutex);
 701                n->tx_flush = true;
 702                mutex_unlock(&n->dev.vqs[VHOST_NET_VQ_TX].mutex);
 703                /* Wait for all lower device DMAs done. */
 704                vhost_ubuf_put_and_wait(n->dev.vqs[VHOST_NET_VQ_TX].ubufs);
 705                mutex_lock(&n->dev.vqs[VHOST_NET_VQ_TX].mutex);
 706                n->tx_flush = false;
 707                kref_init(&n->dev.vqs[VHOST_NET_VQ_TX].ubufs->kref);
 708                mutex_unlock(&n->dev.vqs[VHOST_NET_VQ_TX].mutex);
 709        }
 710}
 711
 712static int vhost_net_release(struct inode *inode, struct file *f)
 713{
 714        struct vhost_net *n = f->private_data;
 715        struct socket *tx_sock;
 716        struct socket *rx_sock;
 717
 718        vhost_net_stop(n, &tx_sock, &rx_sock);
 719        vhost_net_flush(n);
 720        vhost_dev_stop(&n->dev);
 721        vhost_dev_cleanup(&n->dev, false);
 722        if (tx_sock)
 723                fput(tx_sock->file);
 724        if (rx_sock)
 725                fput(rx_sock->file);
 726        /* We do an extra flush before freeing memory,
 727         * since jobs can re-queue themselves. */
 728        vhost_net_flush(n);
 729        kfree(n);
 730        return 0;
 731}
 732
 733static struct socket *get_raw_socket(int fd)
 734{
 735        struct {
 736                struct sockaddr_ll sa;
 737                char  buf[MAX_ADDR_LEN];
 738        } uaddr;
 739        int uaddr_len = sizeof uaddr, r;
 740        struct socket *sock = sockfd_lookup(fd, &r);
 741
 742        if (!sock)
 743                return ERR_PTR(-ENOTSOCK);
 744
 745        /* Parameter checking */
 746        if (sock->sk->sk_type != SOCK_RAW) {
 747                r = -ESOCKTNOSUPPORT;
 748                goto err;
 749        }
 750
 751        r = sock->ops->getname(sock, (struct sockaddr *)&uaddr.sa,
 752                               &uaddr_len, 0);
 753        if (r)
 754                goto err;
 755
 756        if (uaddr.sa.sll_family != AF_PACKET) {
 757                r = -EPFNOSUPPORT;
 758                goto err;
 759        }
 760        return sock;
 761err:
 762        fput(sock->file);
 763        return ERR_PTR(r);
 764}
 765
 766static struct socket *get_tap_socket(int fd)
 767{
 768        struct file *file = fget(fd);
 769        struct socket *sock;
 770
 771        if (!file)
 772                return ERR_PTR(-EBADF);
 773        sock = tun_get_socket(file);
 774        if (!IS_ERR(sock))
 775                return sock;
 776        sock = macvtap_get_socket(file);
 777        if (IS_ERR(sock))
 778                fput(file);
 779        return sock;
 780}
 781
 782static struct socket *get_socket(int fd)
 783{
 784        struct socket *sock;
 785
 786        /* special case to disable backend */
 787        if (fd == -1)
 788                return NULL;
 789        sock = get_raw_socket(fd);
 790        if (!IS_ERR(sock))
 791                return sock;
 792        sock = get_tap_socket(fd);
 793        if (!IS_ERR(sock))
 794                return sock;
 795        return ERR_PTR(-ENOTSOCK);
 796}
 797
 798static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
 799{
 800        struct socket *sock, *oldsock;
 801        struct vhost_virtqueue *vq;
 802        struct vhost_ubuf_ref *ubufs, *oldubufs = NULL;
 803        int r;
 804
 805        mutex_lock(&n->dev.mutex);
 806        r = vhost_dev_check_owner(&n->dev);
 807        if (r)
 808                goto err;
 809
 810        if (index >= VHOST_NET_VQ_MAX) {
 811                r = -ENOBUFS;
 812                goto err;
 813        }
 814        vq = n->vqs + index;
 815        mutex_lock(&vq->mutex);
 816
 817        /* Verify that ring has been setup correctly. */
 818        if (!vhost_vq_access_ok(vq)) {
 819                r = -EFAULT;
 820                goto err_vq;
 821        }
 822        sock = get_socket(fd);
 823        if (IS_ERR(sock)) {
 824                r = PTR_ERR(sock);
 825                goto err_vq;
 826        }
 827
 828        /* start polling new socket */
 829        oldsock = rcu_dereference_protected(vq->private_data,
 830                                            lockdep_is_held(&vq->mutex));
 831        if (sock != oldsock) {
 832                ubufs = vhost_ubuf_alloc(vq, sock && vhost_sock_zcopy(sock));
 833                if (IS_ERR(ubufs)) {
 834                        r = PTR_ERR(ubufs);
 835                        goto err_ubufs;
 836                }
 837
 838                vhost_net_disable_vq(n, vq);
 839                rcu_assign_pointer(vq->private_data, sock);
 840                r = vhost_init_used(vq);
 841                if (r)
 842                        goto err_used;
 843                r = vhost_net_enable_vq(n, vq);
 844                if (r)
 845                        goto err_used;
 846
 847                oldubufs = vq->ubufs;
 848                vq->ubufs = ubufs;
 849
 850                n->tx_packets = 0;
 851                n->tx_zcopy_err = 0;
 852                n->tx_flush = false;
 853        }
 854
 855        mutex_unlock(&vq->mutex);
 856
 857        if (oldubufs) {
 858                vhost_ubuf_put_and_wait(oldubufs);
 859                mutex_lock(&vq->mutex);
 860                vhost_zerocopy_signal_used(n, vq);
 861                mutex_unlock(&vq->mutex);
 862        }
 863
 864        if (oldsock) {
 865                vhost_net_flush_vq(n, index);
 866                fput(oldsock->file);
 867        }
 868
 869        mutex_unlock(&n->dev.mutex);
 870        return 0;
 871
 872err_used:
 873        rcu_assign_pointer(vq->private_data, oldsock);
 874        vhost_net_enable_vq(n, vq);
 875        if (ubufs)
 876                vhost_ubuf_put_and_wait(ubufs);
 877err_ubufs:
 878        fput(sock->file);
 879err_vq:
 880        mutex_unlock(&vq->mutex);
 881err:
 882        mutex_unlock(&n->dev.mutex);
 883        return r;
 884}
 885
 886static long vhost_net_reset_owner(struct vhost_net *n)
 887{
 888        struct socket *tx_sock = NULL;
 889        struct socket *rx_sock = NULL;
 890        long err;
 891
 892        mutex_lock(&n->dev.mutex);
 893        err = vhost_dev_check_owner(&n->dev);
 894        if (err)
 895                goto done;
 896        vhost_net_stop(n, &tx_sock, &rx_sock);
 897        vhost_net_flush(n);
 898        err = vhost_dev_reset_owner(&n->dev);
 899done:
 900        mutex_unlock(&n->dev.mutex);
 901        if (tx_sock)
 902                fput(tx_sock->file);
 903        if (rx_sock)
 904                fput(rx_sock->file);
 905        return err;
 906}
 907
 908static int vhost_net_set_features(struct vhost_net *n, u64 features)
 909{
 910        size_t vhost_hlen, sock_hlen, hdr_len;
 911        int i;
 912
 913        hdr_len = (features & (1 << VIRTIO_NET_F_MRG_RXBUF)) ?
 914                        sizeof(struct virtio_net_hdr_mrg_rxbuf) :
 915                        sizeof(struct virtio_net_hdr);
 916        if (features & (1 << VHOST_NET_F_VIRTIO_NET_HDR)) {
 917                /* vhost provides vnet_hdr */
 918                vhost_hlen = hdr_len;
 919                sock_hlen = 0;
 920        } else {
 921                /* socket provides vnet_hdr */
 922                vhost_hlen = 0;
 923                sock_hlen = hdr_len;
 924        }
 925        mutex_lock(&n->dev.mutex);
 926        if ((features & (1 << VHOST_F_LOG_ALL)) &&
 927            !vhost_log_access_ok(&n->dev)) {
 928                mutex_unlock(&n->dev.mutex);
 929                return -EFAULT;
 930        }
 931        n->dev.acked_features = features;
 932        smp_wmb();
 933        for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
 934                mutex_lock(&n->vqs[i].mutex);
 935                n->vqs[i].vhost_hlen = vhost_hlen;
 936                n->vqs[i].sock_hlen = sock_hlen;
 937                mutex_unlock(&n->vqs[i].mutex);
 938        }
 939        vhost_net_flush(n);
 940        mutex_unlock(&n->dev.mutex);
 941        return 0;
 942}
 943
 944static long vhost_net_ioctl(struct file *f, unsigned int ioctl,
 945                            unsigned long arg)
 946{
 947        struct vhost_net *n = f->private_data;
 948        void __user *argp = (void __user *)arg;
 949        u64 __user *featurep = argp;
 950        struct vhost_vring_file backend;
 951        u64 features;
 952        int r;
 953
 954        switch (ioctl) {
 955        case VHOST_NET_SET_BACKEND:
 956                if (copy_from_user(&backend, argp, sizeof backend))
 957                        return -EFAULT;
 958                return vhost_net_set_backend(n, backend.index, backend.fd);
 959        case VHOST_GET_FEATURES:
 960                features = VHOST_NET_FEATURES;
 961                if (copy_to_user(featurep, &features, sizeof features))
 962                        return -EFAULT;
 963                return 0;
 964        case VHOST_SET_FEATURES:
 965                if (copy_from_user(&features, featurep, sizeof features))
 966                        return -EFAULT;
 967                if (features & ~VHOST_NET_FEATURES)
 968                        return -EOPNOTSUPP;
 969                return vhost_net_set_features(n, features);
 970        case VHOST_RESET_OWNER:
 971                return vhost_net_reset_owner(n);
 972        default:
 973                mutex_lock(&n->dev.mutex);
 974                r = vhost_dev_ioctl(&n->dev, ioctl, argp);
 975                if (r == -ENOIOCTLCMD)
 976                        r = vhost_vring_ioctl(&n->dev, ioctl, argp);
 977                else
 978                        vhost_net_flush(n);
 979                mutex_unlock(&n->dev.mutex);
 980                return r;
 981        }
 982}
 983
 984#ifdef CONFIG_COMPAT
 985static long vhost_net_compat_ioctl(struct file *f, unsigned int ioctl,
 986                                   unsigned long arg)
 987{
 988        return vhost_net_ioctl(f, ioctl, (unsigned long)compat_ptr(arg));
 989}
 990#endif
 991
 992static const struct file_operations vhost_net_fops = {
 993        .owner          = THIS_MODULE,
 994        .release        = vhost_net_release,
 995        .unlocked_ioctl = vhost_net_ioctl,
 996#ifdef CONFIG_COMPAT
 997        .compat_ioctl   = vhost_net_compat_ioctl,
 998#endif
 999        .open           = vhost_net_open,
1000        .llseek         = noop_llseek,
1001};
1002
1003static struct miscdevice vhost_net_misc = {
1004        .minor = VHOST_NET_MINOR,
1005        .name = "vhost-net",
1006        .fops = &vhost_net_fops,
1007};
1008
1009static int vhost_net_init(void)
1010{
1011        if (experimental_zcopytx)
1012                vhost_enable_zcopy(VHOST_NET_VQ_TX);
1013        return misc_register(&vhost_net_misc);
1014}
1015module_init(vhost_net_init);
1016
1017static void vhost_net_exit(void)
1018{
1019        misc_deregister(&vhost_net_misc);
1020}
1021module_exit(vhost_net_exit);
1022
1023MODULE_VERSION("0.0.1");
1024MODULE_LICENSE("GPL v2");
1025MODULE_AUTHOR("Michael S. Tsirkin");
1026MODULE_DESCRIPTION("Host kernel accelerator for virtio net");
1027MODULE_ALIAS_MISCDEV(VHOST_NET_MINOR);
1028MODULE_ALIAS("devname:vhost-net");
1029
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