drivers/vhost/net.c

   1 /* Copyright (C) 2009 Red Hat, Inc.
   2  * Author: Michael S. Tsirkin <mst@redhat.com>
   3  *
   4  * This work is licensed under the terms of the GNU GPL, version 2.
   5  *
   6  * virtio-net server in host kernel.
   7  */
   8
   9 #include <linux/compat.h>
  10 #include <linux/eventfd.h>
  11 #include <linux/vhost.h>
  12 #include <linux/virtio_net.h>
  13 #include <linux/miscdevice.h>
  14 #include <linux/module.h>
  15 #include <linux/moduleparam.h>
  16 #include <linux/mutex.h>
  17 #include <linux/workqueue.h>
  18 #include <linux/file.h>
  19 #include <linux/slab.h>
  20 #include <linux/sched/clock.h>
  21 #include <linux/sched/signal.h>
  22 #include <linux/vmalloc.h>
  23
  24 #include <linux/net.h>
  25 #include <linux/if_packet.h>
  26 #include <linux/if_arp.h>
  27 #include <linux/if_tun.h>
  28 #include <linux/if_macvlan.h>
  29 #include <linux/if_tap.h>
  30 #include <linux/if_vlan.h>
  31 #include <linux/skb_array.h>
  32 #include <linux/skbuff.h>
  33
  34 #include <net/sock.h>
  35 #include <net/xdp.h>
  36
  37 #include "vhost.h"
  38
  39 static int experimental_zcopytx = 1;
  40 module_param(experimental_zcopytx, int, 0444);
  41 MODULE_PARM_DESC(experimental_zcopytx, "Enable Zero Copy TX;"
  42                                        " 1 -Enable; 0 - Disable");
  43
  44 /* Max number of bytes transferred before requeueing the job.
  45  * Using this limit prevents one virtqueue from starving others. */
  46 #define VHOST_NET_WEIGHT 0x80000
  47
  48 /* Max number of packets transferred before requeueing the job.
  49  * Using this limit prevents one virtqueue from starving others with small
  50  * pkts.
  51  */
  52 #define VHOST_NET_PKT_WEIGHT 256
  53
  54 /* MAX number of TX used buffers for outstanding zerocopy */
  55 #define VHOST_MAX_PEND 128
  56 #define VHOST_GOODCOPY_LEN 256
  57
  58 /*
  59  * For transmit, used buffer len is unused; we override it to track buffer
  60  * status internally; used for zerocopy tx only.
  61  */
  62 /* Lower device DMA failed */
  63 #define VHOST_DMA_FAILED_LEN    ((__force __virtio32)3)
  64 /* Lower device DMA done */
  65 #define VHOST_DMA_DONE_LEN      ((__force __virtio32)2)
  66 /* Lower device DMA in progress */
  67 #define VHOST_DMA_IN_PROGRESS   ((__force __virtio32)1)
  68 /* Buffer unused */
  69 #define VHOST_DMA_CLEAR_LEN     ((__force __virtio32)0)
  70
  71 #define VHOST_DMA_IS_DONE(len) ((__force u32)(len) >= (__force u32)VHOST_DMA_DONE_LEN)
  72
  73 enum {
  74         VHOST_NET_FEATURES = VHOST_FEATURES |
  75                          (1ULL << VHOST_NET_F_VIRTIO_NET_HDR) |
  76                          (1ULL << VIRTIO_NET_F_MRG_RXBUF) |
  77                          (1ULL << VIRTIO_F_IOMMU_PLATFORM)
  78 };
  79
  80 enum {
  81         VHOST_NET_VQ_RX = 0,
  82         VHOST_NET_VQ_TX = 1,
  83         VHOST_NET_VQ_MAX = 2,
  84 };
  85
  86 struct vhost_net_ubuf_ref {
  87         /* refcount follows semantics similar to kref:
  88          *  0: object is released
  89          *  1: no outstanding ubufs
  90          * >1: outstanding ubufs
  91          */
  92         atomic_t refcount;
  93         wait_queue_head_t wait;
  94         struct vhost_virtqueue *vq;
  95 };
  96
  97 #define VHOST_RX_BATCH 64
  98 struct vhost_net_buf {
  99         void **queue;
 100         int tail;
 101         int head;
 102 };
 103
 104 struct vhost_net_virtqueue {
 105         struct vhost_virtqueue vq;
 106         size_t vhost_hlen;
 107         size_t sock_hlen;
 108         /* vhost zerocopy support fields below: */
 109         /* last used idx for outstanding DMA zerocopy buffers */
 110         int upend_idx;
 111         /* For TX, first used idx for DMA done zerocopy buffers
 112          * For RX, number of batched heads
 113          */
 114         int done_idx;
 115         /* an array of userspace buffers info */
 116         struct ubuf_info *ubuf_info;
 117         /* Reference counting for outstanding ubufs.
 118          * Protected by vq mutex. Writers must also take device mutex. */
 119         struct vhost_net_ubuf_ref *ubufs;
 120         struct ptr_ring *rx_ring;
 121         struct vhost_net_buf rxq;
 122 };
 123
 124 struct vhost_net {
 125         struct vhost_dev dev;
 126         struct vhost_net_virtqueue vqs[VHOST_NET_VQ_MAX];
 127         struct vhost_poll poll[VHOST_NET_VQ_MAX];
 128         /* Number of TX recently submitted.
 129          * Protected by tx vq lock. */
 130         unsigned tx_packets;
 131         /* Number of times zerocopy TX recently failed.
 132          * Protected by tx vq lock. */
 133         unsigned tx_zcopy_err;
 134         /* Flush in progress. Protected by tx vq lock. */
 135         bool tx_flush;
 136 };
 137
 138 static unsigned vhost_net_zcopy_mask __read_mostly;
 139
 140 static void *vhost_net_buf_get_ptr(struct vhost_net_buf *rxq)
 141 {
 142         if (rxq->tail != rxq->head)
 143                 return rxq->queue[rxq->head];
 144         else
 145                 return NULL;
 146 }
 147
 148 static int vhost_net_buf_get_size(struct vhost_net_buf *rxq)
 149 {
 150         return rxq->tail - rxq->head;
 151 }
 152
 153 static int vhost_net_buf_is_empty(struct vhost_net_buf *rxq)
 154 {
 155         return rxq->tail == rxq->head;
 156 }
 157
 158 static void *vhost_net_buf_consume(struct vhost_net_buf *rxq)
 159 {
 160         void *ret = vhost_net_buf_get_ptr(rxq);
 161         ++rxq->head;
 162         return ret;
 163 }
 164
 165 static int vhost_net_buf_produce(struct vhost_net_virtqueue *nvq)
 166 {
 167         struct vhost_net_buf *rxq = &nvq->rxq;
 168
 169         rxq->head = 0;
 170         rxq->tail = ptr_ring_consume_batched(nvq->rx_ring, rxq->queue,
 171                                               VHOST_RX_BATCH);
 172         return rxq->tail;
 173 }
 174
 175 static void vhost_net_buf_unproduce(struct vhost_net_virtqueue *nvq)
 176 {
 177         struct vhost_net_buf *rxq = &nvq->rxq;
 178
 179         if (nvq->rx_ring && !vhost_net_buf_is_empty(rxq)) {
 180                 ptr_ring_unconsume(nvq->rx_ring, rxq->queue + rxq->head,
 181                                    vhost_net_buf_get_size(rxq),
 182                                    tun_ptr_free);
 183                 rxq->head = rxq->tail = 0;
 184         }
 185 }
 186
 187 static int vhost_net_buf_peek_len(void *ptr)
 188 {
 189         if (tun_is_xdp_frame(ptr)) {
 190                 struct xdp_frame *xdpf = tun_ptr_to_xdp(ptr);
 191
 192                 return xdpf->len;
 193         }
 194
 195         return __skb_array_len_with_tag(ptr);
 196 }
 197
 198 static int vhost_net_buf_peek(struct vhost_net_virtqueue *nvq)
 199 {
 200         struct vhost_net_buf *rxq = &nvq->rxq;
 201
 202         if (!vhost_net_buf_is_empty(rxq))
 203                 goto out;
 204
 205         if (!vhost_net_buf_produce(nvq))
 206                 return 0;
 207
 208 out:
 209         return vhost_net_buf_peek_len(vhost_net_buf_get_ptr(rxq));
 210 }
 211
 212 static void vhost_net_buf_init(struct vhost_net_buf *rxq)
 213 {
 214         rxq->head = rxq->tail = 0;
 215 }
 216
 217 static void vhost_net_enable_zcopy(int vq)
 218 {
 219         vhost_net_zcopy_mask |= 0x1 << vq;
 220 }
 221
 222 static struct vhost_net_ubuf_ref *
 223 vhost_net_ubuf_alloc(struct vhost_virtqueue *vq, bool zcopy)
 224 {
 225         struct vhost_net_ubuf_ref *ubufs;
 226         /* No zero copy backend? Nothing to count. */
 227         if (!zcopy)
 228                 return NULL;
 229         ubufs = kmalloc(sizeof(*ubufs), GFP_KERNEL);
 230         if (!ubufs)
 231                 return ERR_PTR(-ENOMEM);
 232         atomic_set(&ubufs->refcount, 1);
 233         init_waitqueue_head(&ubufs->wait);
 234         ubufs->vq = vq;
 235         return ubufs;
 236 }
 237
 238 static int vhost_net_ubuf_put(struct vhost_net_ubuf_ref *ubufs)
 239 {
 240         int r = atomic_sub_return(1, &ubufs->refcount);
 241         if (unlikely(!r))
 242                 wake_up(&ubufs->wait);
 243         return r;
 244 }
 245
 246 static void vhost_net_ubuf_put_and_wait(struct vhost_net_ubuf_ref *ubufs)
 247 {
 248         vhost_net_ubuf_put(ubufs);
 249         wait_event(ubufs->wait, !atomic_read(&ubufs->refcount));
 250 }
 251
 252 static void vhost_net_ubuf_put_wait_and_free(struct vhost_net_ubuf_ref *ubufs)
 253 {
 254         vhost_net_ubuf_put_and_wait(ubufs);
 255         kfree(ubufs);
 256 }
 257
 258 static void vhost_net_clear_ubuf_info(struct vhost_net *n)
 259 {
 260         int i;
 261
 262         for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
 263                 kfree(n->vqs[i].ubuf_info);
 264                 n->vqs[i].ubuf_info = NULL;
 265         }
 266 }
 267
 268 static int vhost_net_set_ubuf_info(struct vhost_net *n)
 269 {
 270         bool zcopy;
 271         int i;
 272
 273         for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
 274                 zcopy = vhost_net_zcopy_mask & (0x1 << i);
 275                 if (!zcopy)
 276                         continue;
 277                 n->vqs[i].ubuf_info =
 278                         kmalloc_array(UIO_MAXIOV,
 279                                       sizeof(*n->vqs[i].ubuf_info),
 280                                       GFP_KERNEL);
 281                 if  (!n->vqs[i].ubuf_info)
 282                         goto err;
 283         }
 284         return 0;
 285
 286 err:
 287         vhost_net_clear_ubuf_info(n);
 288         return -ENOMEM;
 289 }
 290
 291 static void vhost_net_vq_reset(struct vhost_net *n)
 292 {
 293         int i;
 294
 295         vhost_net_clear_ubuf_info(n);
 296
 297         for (i = 0; i < VHOST_NET_VQ_MAX; i++) {
 298                 n->vqs[i].done_idx = 0;
 299                 n->vqs[i].upend_idx = 0;
 300                 n->vqs[i].ubufs = NULL;
 301                 n->vqs[i].vhost_hlen = 0;
 302                 n->vqs[i].sock_hlen = 0;
 303                 vhost_net_buf_init(&n->vqs[i].rxq);
 304         }
 305
 306 }
 307
 308 static void vhost_net_tx_packet(struct vhost_net *net)
 309 {
 310         ++net->tx_packets;
 311         if (net->tx_packets < 1024)
 312                 return;
 313         net->tx_packets = 0;
 314         net->tx_zcopy_err = 0;
 315 }
 316
 317 static void vhost_net_tx_err(struct vhost_net *net)
 318 {
 319         ++net->tx_zcopy_err;
 320 }
 321
 322 static bool vhost_net_tx_select_zcopy(struct vhost_net *net)
 323 {
 324         /* TX flush waits for outstanding DMAs to be done.
 325          * Don't start new DMAs.
 326          */
 327         return !net->tx_flush &&
 328                 net->tx_packets / 64 >= net->tx_zcopy_err;
 329 }
 330
 331 static bool vhost_sock_zcopy(struct socket *sock)
 332 {
 333         return unlikely(experimental_zcopytx) &&
 334                 sock_flag(sock->sk, SOCK_ZEROCOPY);
 335 }
 336
 337 /* In case of DMA done not in order in lower device driver for some reason.
 338  * upend_idx is used to track end of used idx, done_idx is used to track head
 339  * of used idx. Once lower device DMA done contiguously, we will signal KVM
 340  * guest used idx.
 341  */
 342 static void vhost_zerocopy_signal_used(struct vhost_net *net,
 343                                        struct vhost_virtqueue *vq)
 344 {
 345         struct vhost_net_virtqueue *nvq =
 346                 container_of(vq, struct vhost_net_virtqueue, vq);
 347         int i, add;
 348         int j = 0;
 349
 350         for (i = nvq->done_idx; i != nvq->upend_idx; i = (i + 1) % UIO_MAXIOV) {
 351                 if (vq->heads[i].len == VHOST_DMA_FAILED_LEN)
 352                         vhost_net_tx_err(net);
 353                 if (VHOST_DMA_IS_DONE(vq->heads[i].len)) {
 354                         vq->heads[i].len = VHOST_DMA_CLEAR_LEN;
 355                         ++j;
 356                 } else
 357                         break;
 358         }
 359         while (j) {
 360                 add = min(UIO_MAXIOV - nvq->done_idx, j);
 361                 vhost_add_used_and_signal_n(vq->dev, vq,
 362                                             &vq->heads[nvq->done_idx], add);
 363                 nvq->done_idx = (nvq->done_idx + add) % UIO_MAXIOV;
 364                 j -= add;
 365         }
 366 }
 367
 368 static void vhost_zerocopy_callback(struct ubuf_info *ubuf, bool success)
 369 {
 370         struct vhost_net_ubuf_ref *ubufs = ubuf->ctx;
 371         struct vhost_virtqueue *vq = ubufs->vq;
 372         int cnt;
 373
 374         rcu_read_lock_bh();
 375
 376         /* set len to mark this desc buffers done DMA */
 377         vq->heads[ubuf->desc].len = success ?
 378                 VHOST_DMA_DONE_LEN : VHOST_DMA_FAILED_LEN;
 379         cnt = vhost_net_ubuf_put(ubufs);
 380
 381         /*
 382          * Trigger polling thread if guest stopped submitting new buffers:
 383          * in this case, the refcount after decrement will eventually reach 1.
 384          * We also trigger polling periodically after each 16 packets
 385          * (the value 16 here is more or less arbitrary, it's tuned to trigger
 386          * less than 10% of times).
 387          */
 388         if (cnt <= 1 || !(cnt % 16))
 389                 vhost_poll_queue(&vq->poll);
 390
 391         rcu_read_unlock_bh();
 392 }
 393
 394 static inline unsigned long busy_clock(void)
 395 {
 396         return local_clock() >> 10;
 397 }
 398
 399 static bool vhost_can_busy_poll(struct vhost_dev *dev,
 400                                 unsigned long endtime)
 401 {
 402         return likely(!need_resched()) &&
 403                likely(!time_after(busy_clock(), endtime)) &&
 404                likely(!signal_pending(current)) &&
 405                !vhost_has_work(dev);
 406 }
 407
 408 static void vhost_net_disable_vq(struct vhost_net *n,
 409                                  struct vhost_virtqueue *vq)
 410 {
 411         struct vhost_net_virtqueue *nvq =
 412                 container_of(vq, struct vhost_net_virtqueue, vq);
 413         struct vhost_poll *poll = n->poll + (nvq - n->vqs);
 414         if (!vq->private_data)
 415                 return;
 416         vhost_poll_stop(poll);
 417 }
 418
 419 static int vhost_net_enable_vq(struct vhost_net *n,
 420                                 struct vhost_virtqueue *vq)
 421 {
 422         struct vhost_net_virtqueue *nvq =
 423                 container_of(vq, struct vhost_net_virtqueue, vq);
 424         struct vhost_poll *poll = n->poll + (nvq - n->vqs);
 425         struct socket *sock;
 426
 427         sock = vq->private_data;
 428         if (!sock)
 429                 return 0;
 430
 431         return vhost_poll_start(poll, sock->file);
 432 }
 433
 434 static int vhost_net_tx_get_vq_desc(struct vhost_net *net,
 435                                     struct vhost_virtqueue *vq,
 436                                     struct iovec iov[], unsigned int iov_size,
 437                                     unsigned int *out_num, unsigned int *in_num)
 438 {
 439         unsigned long uninitialized_var(endtime);
 440         int r = vhost_get_vq_desc(vq, vq->iov, ARRAY_SIZE(vq->iov),
 441                                   out_num, in_num, NULL, NULL);
 442
 443         if (r == vq->num && vq->busyloop_timeout) {
 444                 preempt_disable();
 445                 endtime = busy_clock() + vq->busyloop_timeout;
 446                 while (vhost_can_busy_poll(vq->dev, endtime) &&
 447                        vhost_vq_avail_empty(vq->dev, vq))
 448                         cpu_relax();
 449                 preempt_enable();
 450                 r = vhost_get_vq_desc(vq, vq->iov, ARRAY_SIZE(vq->iov),
 451                                       out_num, in_num, NULL, NULL);
 452         }
 453
 454         return r;
 455 }
 456
 457 static bool vhost_exceeds_maxpend(struct vhost_net *net)
 458 {
 459         struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
 460         struct vhost_virtqueue *vq = &nvq->vq;
 461
 462         return (nvq->upend_idx + UIO_MAXIOV - nvq->done_idx) % UIO_MAXIOV >
 463                min_t(unsigned int, VHOST_MAX_PEND, vq->num >> 2);
 464 }
 465
 466 /* Expects to be always run from workqueue - which acts as
 467  * read-size critical section for our kind of RCU. */
 468 static void handle_tx(struct vhost_net *net)
 469 {
 470         struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
 471         struct vhost_virtqueue *vq = &nvq->vq;
 472         unsigned out, in;
 473         int head;
 474         struct msghdr msg = {
 475                 .msg_name = NULL,
 476                 .msg_namelen = 0,
 477                 .msg_control = NULL,
 478                 .msg_controllen = 0,
 479                 .msg_flags = MSG_DONTWAIT,
 480         };
 481         size_t len, total_len = 0;
 482         int err;
 483         size_t hdr_size;
 484         struct socket *sock;
 485         struct vhost_net_ubuf_ref *uninitialized_var(ubufs);
 486         bool zcopy, zcopy_used;
 487         int sent_pkts = 0;
 488
 489         mutex_lock(&vq->mutex);
 490         sock = vq->private_data;
 491         if (!sock)
 492                 goto out;
 493
 494         if (!vq_iotlb_prefetch(vq))
 495                 goto out;
 496
 497         vhost_disable_notify(&net->dev, vq);
 498         vhost_net_disable_vq(net, vq);
 499
 500         hdr_size = nvq->vhost_hlen;
 501         zcopy = nvq->ubufs;
 502
 503         for (;;) {
 504                 /* Release DMAs done buffers first */
 505                 if (zcopy)
 506                         vhost_zerocopy_signal_used(net, vq);
 507
 508
 509                 head = vhost_net_tx_get_vq_desc(net, vq, vq->iov,
 510                                                 ARRAY_SIZE(vq->iov),
 511                                                 &out, &in);
 512                 /* On error, stop handling until the next kick. */
 513                 if (unlikely(head < 0))
 514                         break;
 515                 /* Nothing new?  Wait for eventfd to tell us they refilled. */
 516                 if (head == vq->num) {
 517                         if (unlikely(vhost_enable_notify(&net->dev, vq))) {
 518                                 vhost_disable_notify(&net->dev, vq);
 519                                 continue;
 520                         }
 521                         break;
 522                 }
 523                 if (in) {
 524                         vq_err(vq, "Unexpected descriptor format for TX: "
 525                                "out %d, int %d\n", out, in);
 526                         break;
 527                 }
 528                 /* Skip header. TODO: support TSO. */
 529                 len = iov_length(vq->iov, out);
 530                 iov_iter_init(&msg.msg_iter, WRITE, vq->iov, out, len);
 531                 iov_iter_advance(&msg.msg_iter, hdr_size);
 532                 /* Sanity check */
 533                 if (!msg_data_left(&msg)) {
 534                         vq_err(vq, "Unexpected header len for TX: "
 535                                "%zd expected %zd\n",
 536                                len, hdr_size);
 537                         break;
 538                 }
 539                 len = msg_data_left(&msg);
 540
 541                 zcopy_used = zcopy && len >= VHOST_GOODCOPY_LEN
 542                                    && !vhost_exceeds_maxpend(net)
 543                                    && vhost_net_tx_select_zcopy(net);
 544
 545                 /* use msg_control to pass vhost zerocopy ubuf info to skb */
 546                 if (zcopy_used) {
 547                         struct ubuf_info *ubuf;
 548                         ubuf = nvq->ubuf_info + nvq->upend_idx;
 549
 550                         vq->heads[nvq->upend_idx].id = cpu_to_vhost32(vq, head);
 551                         vq->heads[nvq->upend_idx].len = VHOST_DMA_IN_PROGRESS;
 552                         ubuf->callback = vhost_zerocopy_callback;
 553                         ubuf->ctx = nvq->ubufs;
 554                         ubuf->desc = nvq->upend_idx;
 555                         refcount_set(&ubuf->refcnt, 1);
 556                         msg.msg_control = ubuf;
 557                         msg.msg_controllen = sizeof(ubuf);
 558                         ubufs = nvq->ubufs;
 559                         atomic_inc(&ubufs->refcount);
 560                         nvq->upend_idx = (nvq->upend_idx + 1) % UIO_MAXIOV;
 561                 } else {
 562                         msg.msg_control = NULL;
 563                         ubufs = NULL;
 564                 }
 565
 566                 total_len += len;
 567                 if (total_len < VHOST_NET_WEIGHT &&
 568                     !vhost_vq_avail_empty(&net->dev, vq) &&
 569                     likely(!vhost_exceeds_maxpend(net))) {
 570                         msg.msg_flags |= MSG_MORE;
 571                 } else {
 572                         msg.msg_flags &= ~MSG_MORE;
 573                 }
 574
 575                 /* TODO: Check specific error and bomb out unless ENOBUFS? */
 576                 err = sock->ops->sendmsg(sock, &msg, len);
 577                 if (unlikely(err < 0)) {
 578                         if (zcopy_used) {
 579                                 vhost_net_ubuf_put(ubufs);
 580                                 nvq->upend_idx = ((unsigned)nvq->upend_idx - 1)
 581                                         % UIO_MAXIOV;
 582                         }
 583                         vhost_discard_vq_desc(vq, 1);
 584                         vhost_net_enable_vq(net, vq);
 585                         break;
 586                 }
 587                 if (err != len)
 588                         pr_debug("Truncated TX packet: "
 589                                  " len %d != %zd\n", err, len);
 590                 if (!zcopy_used)
 591                         vhost_add_used_and_signal(&net->dev, vq, head, 0);
 592                 else
 593                         vhost_zerocopy_signal_used(net, vq);
 594                 vhost_net_tx_packet(net);
 595                 if (unlikely(total_len >= VHOST_NET_WEIGHT) ||
 596                     unlikely(++sent_pkts >= VHOST_NET_PKT_WEIGHT)) {
 597                         vhost_poll_queue(&vq->poll);
 598                         break;
 599                 }
 600         }
 601 out:
 602         mutex_unlock(&vq->mutex);
 603 }
 604
 605 static int peek_head_len(struct vhost_net_virtqueue *rvq, struct sock *sk)
 606 {
 607         struct sk_buff *head;
 608         int len = 0;
 609         unsigned long flags;
 610
 611         if (rvq->rx_ring)
 612                 return vhost_net_buf_peek(rvq);
 613
 614         spin_lock_irqsave(&sk->sk_receive_queue.lock, flags);
 615         head = skb_peek(&sk->sk_receive_queue);
 616         if (likely(head)) {
 617                 len = head->len;
 618                 if (skb_vlan_tag_present(head))
 619                         len += VLAN_HLEN;
 620         }
 621
 622         spin_unlock_irqrestore(&sk->sk_receive_queue.lock, flags);
 623         return len;
 624 }
 625
 626 static int sk_has_rx_data(struct sock *sk)
 627 {
 628         struct socket *sock = sk->sk_socket;
 629
 630         if (sock->ops->peek_len)
 631                 return sock->ops->peek_len(sock);
 632
 633         return skb_queue_empty(&sk->sk_receive_queue);
 634 }
 635
 636 static void vhost_rx_signal_used(struct vhost_net_virtqueue *nvq)
 637 {
 638         struct vhost_virtqueue *vq = &nvq->vq;
 639         struct vhost_dev *dev = vq->dev;
 640
 641         if (!nvq->done_idx)
 642                 return;
 643
 644         vhost_add_used_and_signal_n(dev, vq, vq->heads, nvq->done_idx);
 645         nvq->done_idx = 0;
 646 }
 647
 648 static int vhost_net_rx_peek_head_len(struct vhost_net *net, struct sock *sk)
 649 {
 650         struct vhost_net_virtqueue *rvq = &net->vqs[VHOST_NET_VQ_RX];
 651         struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
 652         struct vhost_virtqueue *vq = &nvq->vq;
 653         unsigned long uninitialized_var(endtime);
 654         int len = peek_head_len(rvq, sk);
 655
 656         if (!len && vq->busyloop_timeout) {
 657                 /* Flush batched heads first */
 658                 vhost_rx_signal_used(rvq);
 659                 /* Both tx vq and rx socket were polled here */
 660                 mutex_lock_nested(&vq->mutex, 1);
 661                 vhost_disable_notify(&net->dev, vq);
 662
 663                 preempt_disable();
 664                 endtime = busy_clock() + vq->busyloop_timeout;
 665
 666                 while (vhost_can_busy_poll(&net->dev, endtime) &&
 667                        !sk_has_rx_data(sk) &&
 668                        vhost_vq_avail_empty(&net->dev, vq))
 669                         cpu_relax();
 670
 671                 preempt_enable();
 672
 673                 if (!vhost_vq_avail_empty(&net->dev, vq))
 674                         vhost_poll_queue(&vq->poll);
 675                 else if (unlikely(vhost_enable_notify(&net->dev, vq))) {
 676                         vhost_disable_notify(&net->dev, vq);
 677                         vhost_poll_queue(&vq->poll);
 678                 }
 679
 680                 mutex_unlock(&vq->mutex);
 681
 682                 len = peek_head_len(rvq, sk);
 683         }
 684
 685         return len;
 686 }
 687
 688 /* This is a multi-buffer version of vhost_get_desc, that works if
 689  *      vq has read descriptors only.
 690  * @vq          - the relevant virtqueue
 691  * @datalen     - data length we'll be reading
 692  * @iovcount    - returned count of io vectors we fill
 693  * @log         - vhost log
 694  * @log_num     - log offset
 695  * @quota       - headcount quota, 1 for big buffer
 696  *      returns number of buffer heads allocated, negative on error
 697  */
 698 static int get_rx_bufs(struct vhost_virtqueue *vq,
 699                        struct vring_used_elem *heads,
 700                        int datalen,
 701                        unsigned *iovcount,
 702                        struct vhost_log *log,
 703                        unsigned *log_num,
 704                        unsigned int quota)
 705 {
 706         unsigned int out, in;
 707         int seg = 0;
 708         int headcount = 0;
 709         unsigned d;
 710         int r, nlogs = 0;
 711         /* len is always initialized before use since we are always called with
 712          * datalen > 0.
 713          */
 714         u32 uninitialized_var(len);
 715
 716         while (datalen > 0 && headcount < quota) {
 717                 if (unlikely(seg >= UIO_MAXIOV)) {
 718                         r = -ENOBUFS;
 719                         goto err;
 720                 }
 721                 r = vhost_get_vq_desc(vq, vq->iov + seg,
 722                                       ARRAY_SIZE(vq->iov) - seg, &out,
 723                                       &in, log, log_num);
 724                 if (unlikely(r < 0))
 725                         goto err;
 726
 727                 d = r;
 728                 if (d == vq->num) {
 729                         r = 0;
 730                         goto err;
 731                 }
 732                 if (unlikely(out || in <= 0)) {
 733                         vq_err(vq, "unexpected descriptor format for RX: "
 734                                 "out %d, in %d\n", out, in);
 735                         r = -EINVAL;
 736                         goto err;
 737                 }
 738                 if (unlikely(log)) {
 739                         nlogs += *log_num;
 740                         log += *log_num;
 741                 }
 742                 heads[headcount].id = cpu_to_vhost32(vq, d);
 743                 len = iov_length(vq->iov + seg, in);
 744                 heads[headcount].len = cpu_to_vhost32(vq, len);
 745                 datalen -= len;
 746                 ++headcount;
 747                 seg += in;
 748         }
 749         heads[headcount - 1].len = cpu_to_vhost32(vq, len + datalen);
 750         *iovcount = seg;
 751         if (unlikely(log))
 752                 *log_num = nlogs;
 753
 754         /* Detect overrun */
 755         if (unlikely(datalen > 0)) {
 756                 r = UIO_MAXIOV + 1;
 757                 goto err;
 758         }
 759         return headcount;
 760 err:
 761         vhost_discard_vq_desc(vq, headcount);
 762         return r;
 763 }
 764
 765 /* Expects to be always run from workqueue - which acts as
 766  * read-size critical section for our kind of RCU. */
 767 static void handle_rx(struct vhost_net *net)
 768 {
 769         struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_RX];
 770         struct vhost_virtqueue *vq = &nvq->vq;
 771         unsigned uninitialized_var(in), log;
 772         struct vhost_log *vq_log;
 773         struct msghdr msg = {
 774                 .msg_name = NULL,
 775                 .msg_namelen = 0,
 776                 .msg_control = NULL, /* FIXME: get and handle RX aux data. */
 777                 .msg_controllen = 0,
 778                 .msg_flags = MSG_DONTWAIT,
 779         };
 780         struct virtio_net_hdr hdr = {
 781                 .flags = 0,
 782                 .gso_type = VIRTIO_NET_HDR_GSO_NONE
 783         };
 784         size_t total_len = 0;
 785         int err, mergeable;
 786         s16 headcount;
 787         size_t vhost_hlen, sock_hlen;
 788         size_t vhost_len, sock_len;
 789         struct socket *sock;
 790         struct iov_iter fixup;
 791         __virtio16 num_buffers;
 792         int recv_pkts = 0;
 793
 794         mutex_lock_nested(&vq->mutex, 0);
 795         sock = vq->private_data;
 796         if (!sock)
 797                 goto out;
 798
 799         if (!vq_iotlb_prefetch(vq))
 800                 goto out;
 801
 802         vhost_disable_notify(&net->dev, vq);
 803         vhost_net_disable_vq(net, vq);
 804
 805         vhost_hlen = nvq->vhost_hlen;
 806         sock_hlen = nvq->sock_hlen;
 807
 808         vq_log = unlikely(vhost_has_feature(vq, VHOST_F_LOG_ALL)) ?
 809                 vq->log : NULL;
 810         mergeable = vhost_has_feature(vq, VIRTIO_NET_F_MRG_RXBUF);
 811
 812         while ((sock_len = vhost_net_rx_peek_head_len(net, sock->sk))) {
 813                 sock_len += sock_hlen;
 814                 vhost_len = sock_len + vhost_hlen;
 815                 headcount = get_rx_bufs(vq, vq->heads + nvq->done_idx,
 816                                         vhost_len, &in, vq_log, &log,
 817                                         likely(mergeable) ? UIO_MAXIOV : 1);
 818                 /* On error, stop handling until the next kick. */
 819                 if (unlikely(headcount < 0))
 820                         goto out;
 821                 /* OK, now we need to know about added descriptors. */
 822                 if (!headcount) {
 823                         if (unlikely(vhost_enable_notify(&net->dev, vq))) {
 824                                 /* They have slipped one in as we were
 825                                  * doing that: check again. */
 826                                 vhost_disable_notify(&net->dev, vq);
 827                                 continue;
 828                         }
 829                         /* Nothing new?  Wait for eventfd to tell us
 830                          * they refilled. */
 831                         goto out;
 832                 }
 833                 if (nvq->rx_ring)
 834                         msg.msg_control = vhost_net_buf_consume(&nvq->rxq);
 835                 /* On overrun, truncate and discard */
 836                 if (unlikely(headcount > UIO_MAXIOV)) {
 837                         iov_iter_init(&msg.msg_iter, READ, vq->iov, 1, 1);
 838                         err = sock->ops->recvmsg(sock, &msg,
 839                                                  1, MSG_DONTWAIT | MSG_TRUNC);
 840                         pr_debug("Discarded rx packet: len %zd\n", sock_len);
 841                         continue;
 842                 }
 843                 /* We don't need to be notified again. */
 844                 iov_iter_init(&msg.msg_iter, READ, vq->iov, in, vhost_len);
 845                 fixup = msg.msg_iter;
 846                 if (unlikely((vhost_hlen))) {
 847                         /* We will supply the header ourselves
 848                          * TODO: support TSO.
 849                          */
 850                         iov_iter_advance(&msg.msg_iter, vhost_hlen);
 851                 }
 852                 err = sock->ops->recvmsg(sock, &msg,
 853                                          sock_len, MSG_DONTWAIT | MSG_TRUNC);
 854                 /* Userspace might have consumed the packet meanwhile:
 855                  * it's not supposed to do this usually, but might be hard
 856                  * to prevent. Discard data we got (if any) and keep going. */
 857                 if (unlikely(err != sock_len)) {
 858                         pr_debug("Discarded rx packet: "
 859                                  " len %d, expected %zd\n", err, sock_len);
 860                         vhost_discard_vq_desc(vq, headcount);
 861                         continue;
 862                 }
 863                 /* Supply virtio_net_hdr if VHOST_NET_F_VIRTIO_NET_HDR */
 864                 if (unlikely(vhost_hlen)) {
 865                         if (copy_to_iter(&hdr, sizeof(hdr),
 866                                          &fixup) != sizeof(hdr)) {
 867                                 vq_err(vq, "Unable to write vnet_hdr "
 868                                        "at addr %p\n", vq->iov->iov_base);
 869                                 goto out;
 870                         }
 871                 } else {
 872                         /* Header came from socket; we'll need to patch
 873                          * ->num_buffers over if VIRTIO_NET_F_MRG_RXBUF
 874                          */
 875                         iov_iter_advance(&fixup, sizeof(hdr));
 876                 }
 877                 /* TODO: Should check and handle checksum. */
 878
 879                 num_buffers = cpu_to_vhost16(vq, headcount);
 880                 if (likely(mergeable) &&
 881                     copy_to_iter(&num_buffers, sizeof num_buffers,
 882                                  &fixup) != sizeof num_buffers) {
 883                         vq_err(vq, "Failed num_buffers write");
 884                         vhost_discard_vq_desc(vq, headcount);
 885                         goto out;
 886                 }
 887                 nvq->done_idx += headcount;
 888                 if (nvq->done_idx > VHOST_RX_BATCH)
 889                         vhost_rx_signal_used(nvq);
 890                 if (unlikely(vq_log))
 891                         vhost_log_write(vq, vq_log, log, vhost_len);
 892                 total_len += vhost_len;
 893                 if (unlikely(total_len >= VHOST_NET_WEIGHT) ||
 894                     unlikely(++recv_pkts >= VHOST_NET_PKT_WEIGHT)) {
 895                         vhost_poll_queue(&vq->poll);
 896                         goto out;
 897                 }
 898         }
 899         vhost_net_enable_vq(net, vq);
 900 out:
 901         vhost_rx_signal_used(nvq);
 902         mutex_unlock(&vq->mutex);
 903 }
 904
 905 static void handle_tx_kick(struct vhost_work *work)
 906 {
 907         struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
 908                                                   poll.work);
 909         struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev);
 910
 911         handle_tx(net);
 912 }
 913
 914 static void handle_rx_kick(struct vhost_work *work)
 915 {
 916         struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
 917                                                   poll.work);
 918         struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev);
 919
 920         handle_rx(net);
 921 }
 922
 923 static void handle_tx_net(struct vhost_work *work)
 924 {
 925         struct vhost_net *net = container_of(work, struct vhost_net,
 926                                              poll[VHOST_NET_VQ_TX].work);
 927         handle_tx(net);
 928 }
 929
 930 static void handle_rx_net(struct vhost_work *work)
 931 {
 932         struct vhost_net *net = container_of(work, struct vhost_net,
 933                                              poll[VHOST_NET_VQ_RX].work);
 934         handle_rx(net);
 935 }
 936
 937 static int vhost_net_open(struct inode *inode, struct file *f)
 938 {
 939         struct vhost_net *n;
 940         struct vhost_dev *dev;
 941         struct vhost_virtqueue **vqs;
 942         void **queue;
 943         int i;
 944
 945         n = kvmalloc(sizeof *n, GFP_KERNEL | __GFP_RETRY_MAYFAIL);
 946         if (!n)
 947                 return -ENOMEM;
 948         vqs = kmalloc_array(VHOST_NET_VQ_MAX, sizeof(*vqs), GFP_KERNEL);
 949         if (!vqs) {
 950                 kvfree(n);
 951                 return -ENOMEM;
 952         }
 953
 954         queue = kmalloc_array(VHOST_RX_BATCH, sizeof(void *),
 955                               GFP_KERNEL);
 956         if (!queue) {
 957                 kfree(vqs);
 958                 kvfree(n);
 959                 return -ENOMEM;
 960         }
 961         n->vqs[VHOST_NET_VQ_RX].rxq.queue = queue;
 962
 963         dev = &n->dev;
 964         vqs[VHOST_NET_VQ_TX] = &n->vqs[VHOST_NET_VQ_TX].vq;
 965         vqs[VHOST_NET_VQ_RX] = &n->vqs[VHOST_NET_VQ_RX].vq;
 966         n->vqs[VHOST_NET_VQ_TX].vq.handle_kick = handle_tx_kick;
 967         n->vqs[VHOST_NET_VQ_RX].vq.handle_kick = handle_rx_kick;
 968         for (i = 0; i < VHOST_NET_VQ_MAX; i++) {
 969                 n->vqs[i].ubufs = NULL;
 970                 n->vqs[i].ubuf_info = NULL;
 971                 n->vqs[i].upend_idx = 0;
 972                 n->vqs[i].done_idx = 0;
 973                 n->vqs[i].vhost_hlen = 0;
 974                 n->vqs[i].sock_hlen = 0;
 975                 n->vqs[i].rx_ring = NULL;
 976                 vhost_net_buf_init(&n->vqs[i].rxq);
 977         }
 978         vhost_dev_init(dev, vqs, VHOST_NET_VQ_MAX);
 979
 980         vhost_poll_init(n->poll + VHOST_NET_VQ_TX, handle_tx_net, EPOLLOUT, dev);
 981         vhost_poll_init(n->poll + VHOST_NET_VQ_RX, handle_rx_net, EPOLLIN, dev);
 982
 983         f->private_data = n;
 984
 985         return 0;
 986 }
 987
 988 static struct socket *vhost_net_stop_vq(struct vhost_net *n,
 989                                         struct vhost_virtqueue *vq)
 990 {
 991         struct socket *sock;
 992         struct vhost_net_virtqueue *nvq =
 993                 container_of(vq, struct vhost_net_virtqueue, vq);
 994
 995         mutex_lock(&vq->mutex);
 996         sock = vq->private_data;
 997         vhost_net_disable_vq(n, vq);
 998         vq->private_data = NULL;
 999         vhost_net_buf_unproduce(nvq);
1000         nvq->rx_ring = NULL;
1001         mutex_unlock(&vq->mutex);
1002         return sock;
1003 }
1004
1005 static void vhost_net_stop(struct vhost_net *n, struct socket **tx_sock,
1006                            struct socket **rx_sock)
1007 {
1008         *tx_sock = vhost_net_stop_vq(n, &n->vqs[VHOST_NET_VQ_TX].vq);
1009         *rx_sock = vhost_net_stop_vq(n, &n->vqs[VHOST_NET_VQ_RX].vq);
1010 }
1011
1012 static void vhost_net_flush_vq(struct vhost_net *n, int index)
1013 {
1014         vhost_poll_flush(n->poll + index);
1015         vhost_poll_flush(&n->vqs[index].vq.poll);
1016 }
1017
1018 static void vhost_net_flush(struct vhost_net *n)
1019 {
1020         vhost_net_flush_vq(n, VHOST_NET_VQ_TX);
1021         vhost_net_flush_vq(n, VHOST_NET_VQ_RX);
1022         if (n->vqs[VHOST_NET_VQ_TX].ubufs) {
1023                 mutex_lock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
1024                 n->tx_flush = true;
1025                 mutex_unlock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
1026                 /* Wait for all lower device DMAs done. */
1027                 vhost_net_ubuf_put_and_wait(n->vqs[VHOST_NET_VQ_TX].ubufs);
1028                 mutex_lock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
1029                 n->tx_flush = false;
1030                 atomic_set(&n->vqs[VHOST_NET_VQ_TX].ubufs->refcount, 1);
1031                 mutex_unlock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
1032         }
1033 }
1034
1035 static int vhost_net_release(struct inode *inode, struct file *f)
1036 {
1037         struct vhost_net *n = f->private_data;
1038         struct socket *tx_sock;
1039         struct socket *rx_sock;
1040
1041         vhost_net_stop(n, &tx_sock, &rx_sock);
1042         vhost_net_flush(n);
1043         vhost_dev_stop(&n->dev);
1044         vhost_dev_cleanup(&n->dev);
1045         vhost_net_vq_reset(n);
1046         if (tx_sock)
1047                 sockfd_put(tx_sock);
1048         if (rx_sock)
1049                 sockfd_put(rx_sock);
1050         /* Make sure no callbacks are outstanding */
1051         synchronize_rcu_bh();
1052         /* We do an extra flush before freeing memory,
1053          * since jobs can re-queue themselves. */
1054         vhost_net_flush(n);
1055         kfree(n->vqs[VHOST_NET_VQ_RX].rxq.queue);
1056         kfree(n->dev.vqs);
1057         kvfree(n);
1058         return 0;
1059 }
1060
1061 static struct socket *get_raw_socket(int fd)
1062 {
1063         struct {
1064                 struct sockaddr_ll sa;
1065                 char  buf[MAX_ADDR_LEN];
1066         } uaddr;
1067         int r;
1068         struct socket *sock = sockfd_lookup(fd, &r);
1069
1070         if (!sock)
1071                 return ERR_PTR(-ENOTSOCK);
1072
1073         /* Parameter checking */
1074         if (sock->sk->sk_type != SOCK_RAW) {
1075                 r = -ESOCKTNOSUPPORT;
1076                 goto err;
1077         }
1078
1079         r = sock->ops->getname(sock, (struct sockaddr *)&uaddr.sa, 0);
1080         if (r < 0)
1081                 goto err;
1082
1083         if (uaddr.sa.sll_family != AF_PACKET) {
1084                 r = -EPFNOSUPPORT;
1085                 goto err;
1086         }
1087         return sock;
1088 err:
1089         sockfd_put(sock);
1090         return ERR_PTR(r);
1091 }
1092
1093 static struct ptr_ring *get_tap_ptr_ring(int fd)
1094 {
1095         struct ptr_ring *ring;
1096         struct file *file = fget(fd);
1097
1098         if (!file)
1099                 return NULL;
1100         ring = tun_get_tx_ring(file);
1101         if (!IS_ERR(ring))
1102                 goto out;
1103         ring = tap_get_ptr_ring(file);
1104         if (!IS_ERR(ring))
1105                 goto out;
1106         ring = NULL;
1107 out:
1108         fput(file);
1109         return ring;
1110 }
1111
1112 static struct socket *get_tap_socket(int fd)
1113 {
1114         struct file *file = fget(fd);
1115         struct socket *sock;
1116
1117         if (!file)
1118                 return ERR_PTR(-EBADF);
1119         sock = tun_get_socket(file);
1120         if (!IS_ERR(sock))
1121                 return sock;
1122         sock = tap_get_socket(file);
1123         if (IS_ERR(sock))
1124                 fput(file);
1125         return sock;
1126 }
1127
1128 static struct socket *get_socket(int fd)
1129 {
1130         struct socket *sock;
1131
1132         /* special case to disable backend */
1133         if (fd == -1)
1134                 return NULL;
1135         sock = get_raw_socket(fd);
1136         if (!IS_ERR(sock))
1137                 return sock;
1138         sock = get_tap_socket(fd);
1139         if (!IS_ERR(sock))
1140                 return sock;
1141         return ERR_PTR(-ENOTSOCK);
1142 }
1143
1144 static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
1145 {
1146         struct socket *sock, *oldsock;
1147         struct vhost_virtqueue *vq;
1148         struct vhost_net_virtqueue *nvq;
1149         struct vhost_net_ubuf_ref *ubufs, *oldubufs = NULL;
1150         int r;
1151
1152         mutex_lock(&n->dev.mutex);
1153         r = vhost_dev_check_owner(&n->dev);
1154         if (r)
1155                 goto err;
1156
1157         if (index >= VHOST_NET_VQ_MAX) {
1158                 r = -ENOBUFS;
1159                 goto err;
1160         }
1161         vq = &n->vqs[index].vq;
1162         nvq = &n->vqs[index];
1163         mutex_lock(&vq->mutex);
1164
1165         /* Verify that ring has been setup correctly. */
1166         if (!vhost_vq_access_ok(vq)) {
1167                 r = -EFAULT;
1168                 goto err_vq;
1169         }
1170         sock = get_socket(fd);
1171         if (IS_ERR(sock)) {
1172                 r = PTR_ERR(sock);
1173                 goto err_vq;
1174         }
1175
1176         /* start polling new socket */
1177         oldsock = vq->private_data;
1178         if (sock != oldsock) {
1179                 ubufs = vhost_net_ubuf_alloc(vq,
1180                                              sock && vhost_sock_zcopy(sock));
1181                 if (IS_ERR(ubufs)) {
1182                         r = PTR_ERR(ubufs);
1183                         goto err_ubufs;
1184                 }
1185
1186                 vhost_net_disable_vq(n, vq);
1187                 vq->private_data = sock;
1188                 vhost_net_buf_unproduce(nvq);
1189                 r = vhost_vq_init_access(vq);
1190                 if (r)
1191                         goto err_used;
1192                 r = vhost_net_enable_vq(n, vq);
1193                 if (r)
1194                         goto err_used;
1195                 if (index == VHOST_NET_VQ_RX)
1196                         nvq->rx_ring = get_tap_ptr_ring(fd);
1197
1198                 oldubufs = nvq->ubufs;
1199                 nvq->ubufs = ubufs;
1200
1201                 n->tx_packets = 0;
1202                 n->tx_zcopy_err = 0;
1203                 n->tx_flush = false;
1204         }
1205
1206         mutex_unlock(&vq->mutex);
1207
1208         if (oldubufs) {
1209                 vhost_net_ubuf_put_wait_and_free(oldubufs);
1210                 mutex_lock(&vq->mutex);
1211                 vhost_zerocopy_signal_used(n, vq);
1212                 mutex_unlock(&vq->mutex);
1213         }
1214
1215         if (oldsock) {
1216                 vhost_net_flush_vq(n, index);
1217                 sockfd_put(oldsock);
1218         }
1219
1220         mutex_unlock(&n->dev.mutex);
1221         return 0;
1222
1223 err_used:
1224         vq->private_data = oldsock;
1225         vhost_net_enable_vq(n, vq);
1226         if (ubufs)
1227                 vhost_net_ubuf_put_wait_and_free(ubufs);
1228 err_ubufs:
1229         if (sock)
1230                 sockfd_put(sock);
1231 err_vq:
1232         mutex_unlock(&vq->mutex);
1233 err:
1234         mutex_unlock(&n->dev.mutex);
1235         return r;
1236 }
1237
1238 static long vhost_net_reset_owner(struct vhost_net *n)
1239 {
1240         struct socket *tx_sock = NULL;
1241         struct socket *rx_sock = NULL;
1242         long err;
1243         struct vhost_umem *umem;
1244
1245         mutex_lock(&n->dev.mutex);
1246         err = vhost_dev_check_owner(&n->dev);
1247         if (err)
1248                 goto done;
1249         umem = vhost_dev_reset_owner_prepare();
1250         if (!umem) {
1251                 err = -ENOMEM;
1252                 goto done;
1253         }
1254         vhost_net_stop(n, &tx_sock, &rx_sock);
1255         vhost_net_flush(n);
1256         vhost_dev_stop(&n->dev);
1257         vhost_dev_reset_owner(&n->dev, umem);
1258         vhost_net_vq_reset(n);
1259 done:
1260         mutex_unlock(&n->dev.mutex);
1261         if (tx_sock)
1262                 sockfd_put(tx_sock);
1263         if (rx_sock)
1264                 sockfd_put(rx_sock);
1265         return err;
1266 }
1267
1268 static int vhost_net_set_features(struct vhost_net *n, u64 features)
1269 {
1270         size_t vhost_hlen, sock_hlen, hdr_len;
1271         int i;
1272
1273         hdr_len = (features & ((1ULL << VIRTIO_NET_F_MRG_RXBUF) |
1274                                (1ULL << VIRTIO_F_VERSION_1))) ?
1275                         sizeof(struct virtio_net_hdr_mrg_rxbuf) :
1276                         sizeof(struct virtio_net_hdr);
1277         if (features & (1 << VHOST_NET_F_VIRTIO_NET_HDR)) {
1278                 /* vhost provides vnet_hdr */
1279                 vhost_hlen = hdr_len;
1280                 sock_hlen = 0;
1281         } else {
1282                 /* socket provides vnet_hdr */
1283                 vhost_hlen = 0;
1284                 sock_hlen = hdr_len;
1285         }
1286         mutex_lock(&n->dev.mutex);
1287         if ((features & (1 << VHOST_F_LOG_ALL)) &&
1288             !vhost_log_access_ok(&n->dev))
1289                 goto out_unlock;
1290
1291         if ((features & (1ULL << VIRTIO_F_IOMMU_PLATFORM))) {
1292                 if (vhost_init_device_iotlb(&n->dev, true))
1293                         goto out_unlock;
1294         }
1295
1296         for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
1297                 mutex_lock(&n->vqs[i].vq.mutex);
1298                 n->vqs[i].vq.acked_features = features;
1299                 n->vqs[i].vhost_hlen = vhost_hlen;
1300                 n->vqs[i].sock_hlen = sock_hlen;
1301                 mutex_unlock(&n->vqs[i].vq.mutex);
1302         }
1303         mutex_unlock(&n->dev.mutex);
1304         return 0;
1305
1306 out_unlock:
1307         mutex_unlock(&n->dev.mutex);
1308         return -EFAULT;
1309 }
1310
1311 static long vhost_net_set_owner(struct vhost_net *n)
1312 {
1313         int r;
1314
1315         mutex_lock(&n->dev.mutex);
1316         if (vhost_dev_has_owner(&n->dev)) {
1317                 r = -EBUSY;
1318                 goto out;
1319         }
1320         r = vhost_net_set_ubuf_info(n);
1321         if (r)
1322                 goto out;
1323         r = vhost_dev_set_owner(&n->dev);
1324         if (r)
1325                 vhost_net_clear_ubuf_info(n);
1326         vhost_net_flush(n);
1327 out:
1328         mutex_unlock(&n->dev.mutex);
1329         return r;
1330 }
1331
1332 static long vhost_net_ioctl(struct file *f, unsigned int ioctl,
1333                             unsigned long arg)
1334 {
1335         struct vhost_net *n = f->private_data;
1336         void __user *argp = (void __user *)arg;
1337         u64 __user *featurep = argp;
1338         struct vhost_vring_file backend;
1339         u64 features;
1340         int r;
1341
1342         switch (ioctl) {
1343         case VHOST_NET_SET_BACKEND:
1344                 if (copy_from_user(&backend, argp, sizeof backend))
1345                         return -EFAULT;
1346                 return vhost_net_set_backend(n, backend.index, backend.fd);
1347         case VHOST_GET_FEATURES:
1348                 features = VHOST_NET_FEATURES;
1349                 if (copy_to_user(featurep, &features, sizeof features))
1350                         return -EFAULT;
1351                 return 0;
1352         case VHOST_SET_FEATURES:
1353                 if (copy_from_user(&features, featurep, sizeof features))
1354                         return -EFAULT;
1355                 if (features & ~VHOST_NET_FEATURES)
1356                         return -EOPNOTSUPP;
1357                 return vhost_net_set_features(n, features);
1358         case VHOST_RESET_OWNER:
1359                 return vhost_net_reset_owner(n);
1360         case VHOST_SET_OWNER:
1361                 return vhost_net_set_owner(n);
1362         default:
1363                 mutex_lock(&n->dev.mutex);
1364                 r = vhost_dev_ioctl(&n->dev, ioctl, argp);
1365                 if (r == -ENOIOCTLCMD)
1366                         r = vhost_vring_ioctl(&n->dev, ioctl, argp);
1367                 else
1368                         vhost_net_flush(n);
1369                 mutex_unlock(&n->dev.mutex);
1370                 return r;
1371         }
1372 }
1373
1374 #ifdef CONFIG_COMPAT
1375 static long vhost_net_compat_ioctl(struct file *f, unsigned int ioctl,
1376                                    unsigned long arg)
1377 {
1378         return vhost_net_ioctl(f, ioctl, (unsigned long)compat_ptr(arg));
1379 }
1380 #endif
1381
1382 static ssize_t vhost_net_chr_read_iter(struct kiocb *iocb, struct iov_iter *to)
1383 {
1384         struct file *file = iocb->ki_filp;
1385         struct vhost_net *n = file->private_data;
1386         struct vhost_dev *dev = &n->dev;
1387         int noblock = file->f_flags & O_NONBLOCK;
1388
1389         return vhost_chr_read_iter(dev, to, noblock);
1390 }
1391
1392 static ssize_t vhost_net_chr_write_iter(struct kiocb *iocb,
1393                                         struct iov_iter *from)
1394 {
1395         struct file *file = iocb->ki_filp;
1396         struct vhost_net *n = file->private_data;
1397         struct vhost_dev *dev = &n->dev;
1398
1399         return vhost_chr_write_iter(dev, from);
1400 }
1401
1402 static __poll_t vhost_net_chr_poll(struct file *file, poll_table *wait)
1403 {
1404         struct vhost_net *n = file->private_data;
1405         struct vhost_dev *dev = &n->dev;
1406
1407         return vhost_chr_poll(file, dev, wait);
1408 }
1409
1410 static const struct file_operations vhost_net_fops = {
1411         .owner          = THIS_MODULE,
1412         .release        = vhost_net_release,
1413         .read_iter      = vhost_net_chr_read_iter,
1414         .write_iter     = vhost_net_chr_write_iter,
1415         .poll           = vhost_net_chr_poll,
1416         .unlocked_ioctl = vhost_net_ioctl,
1417 #ifdef CONFIG_COMPAT
1418         .compat_ioctl   = vhost_net_compat_ioctl,
1419 #endif
1420         .open           = vhost_net_open,
1421         .llseek         = noop_llseek,
1422 };
1423
1424 static struct miscdevice vhost_net_misc = {
1425         .minor = VHOST_NET_MINOR,
1426         .name = "vhost-net",
1427         .fops = &vhost_net_fops,
1428 };
1429
1430 static int vhost_net_init(void)
1431 {
1432         if (experimental_zcopytx)
1433                 vhost_net_enable_zcopy(VHOST_NET_VQ_TX);
1434         return misc_register(&vhost_net_misc);
1435 }
1436 module_init(vhost_net_init);
1437
1438 static void vhost_net_exit(void)
1439 {
1440         misc_deregister(&vhost_net_misc);
1441 }
1442 module_exit(vhost_net_exit);
1443
1444 MODULE_VERSION("0.0.1");
1445 MODULE_LICENSE("GPL v2");
1446 MODULE_AUTHOR("Michael S. Tsirkin");
1447 MODULE_DESCRIPTION("Host kernel accelerator for virtio net");
1448 MODULE_ALIAS_MISCDEV(VHOST_NET_MINOR);
1449 MODULE_ALIAS("devname:vhost-net");