drivers/vhost/net.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /* Copyright (C) 2009 Red Hat, Inc.
   3  * Author: Michael S. Tsirkin <mst@redhat.com>
   4  *
   5  * virtio-net server in host kernel.
   6  */
   7
   8 #include <linux/compat.h>
   9 #include <linux/eventfd.h>
  10 #include <linux/vhost.h>
  11 #include <linux/virtio_net.h>
  12 #include <linux/miscdevice.h>
  13 #include <linux/module.h>
  14 #include <linux/moduleparam.h>
  15 #include <linux/mutex.h>
  16 #include <linux/workqueue.h>
  17 #include <linux/file.h>
  18 #include <linux/slab.h>
  19 #include <linux/sched/clock.h>
  20 #include <linux/sched/signal.h>
  21 #include <linux/vmalloc.h>
  22
  23 #include <linux/net.h>
  24 #include <linux/if_packet.h>
  25 #include <linux/if_arp.h>
  26 #include <linux/if_tun.h>
  27 #include <linux/if_macvlan.h>
  28 #include <linux/if_tap.h>
  29 #include <linux/if_vlan.h>
  30 #include <linux/skb_array.h>
  31 #include <linux/skbuff.h>
  32
  33 #include <net/sock.h>
  34 #include <net/xdp.h>
  35
  36 #include "vhost.h"
  37
  38 static int experimental_zcopytx = 0;
  39 module_param(experimental_zcopytx, int, 0444);
  40 MODULE_PARM_DESC(experimental_zcopytx, "Enable Zero Copy TX;"
  41                                        " 1 -Enable; 0 - Disable");
  42
  43 /* Max number of bytes transferred before requeueing the job.
  44  * Using this limit prevents one virtqueue from starving others. */
  45 #define VHOST_NET_WEIGHT 0x80000
  46
  47 /* Max number of packets transferred before requeueing the job.
  48  * Using this limit prevents one virtqueue from starving others with small
  49  * pkts.
  50  */
  51 #define VHOST_NET_PKT_WEIGHT 256
  52
  53 /* MAX number of TX used buffers for outstanding zerocopy */
  54 #define VHOST_MAX_PEND 128
  55 #define VHOST_GOODCOPY_LEN 256
  56
  57 /*
  58  * For transmit, used buffer len is unused; we override it to track buffer
  59  * status internally; used for zerocopy tx only.
  60  */
  61 /* Lower device DMA failed */
  62 #define VHOST_DMA_FAILED_LEN    ((__force __virtio32)3)
  63 /* Lower device DMA done */
  64 #define VHOST_DMA_DONE_LEN      ((__force __virtio32)2)
  65 /* Lower device DMA in progress */
  66 #define VHOST_DMA_IN_PROGRESS   ((__force __virtio32)1)
  67 /* Buffer unused */
  68 #define VHOST_DMA_CLEAR_LEN     ((__force __virtio32)0)
  69
  70 #define VHOST_DMA_IS_DONE(len) ((__force u32)(len) >= (__force u32)VHOST_DMA_DONE_LEN)
  71
  72 enum {
  73         VHOST_NET_FEATURES = VHOST_FEATURES |
  74                          (1ULL << VHOST_NET_F_VIRTIO_NET_HDR) |
  75                          (1ULL << VIRTIO_NET_F_MRG_RXBUF) |
  76                          (1ULL << VIRTIO_F_ACCESS_PLATFORM)
  77 };
  78
  79 enum {
  80         VHOST_NET_BACKEND_FEATURES = (1ULL << VHOST_BACKEND_F_IOTLB_MSG_V2)
  81 };
  82
  83 enum {
  84         VHOST_NET_VQ_RX = 0,
  85         VHOST_NET_VQ_TX = 1,
  86         VHOST_NET_VQ_MAX = 2,
  87 };
  88
  89 struct vhost_net_ubuf_ref {
  90         /* refcount follows semantics similar to kref:
  91          *  0: object is released
  92          *  1: no outstanding ubufs
  93          * >1: outstanding ubufs
  94          */
  95         atomic_t refcount;
  96         wait_queue_head_t wait;
  97         struct vhost_virtqueue *vq;
  98 };
  99
 100 #define VHOST_NET_BATCH 64
 101 struct vhost_net_buf {
 102         void **queue;
 103         int tail;
 104         int head;
 105 };
 106
 107 struct vhost_net_virtqueue {
 108         struct vhost_virtqueue vq;
 109         size_t vhost_hlen;
 110         size_t sock_hlen;
 111         /* vhost zerocopy support fields below: */
 112         /* last used idx for outstanding DMA zerocopy buffers */
 113         int upend_idx;
 114         /* For TX, first used idx for DMA done zerocopy buffers
 115          * For RX, number of batched heads
 116          */
 117         int done_idx;
 118         /* Number of XDP frames batched */
 119         int batched_xdp;
 120         /* an array of userspace buffers info */
 121         struct ubuf_info *ubuf_info;
 122         /* Reference counting for outstanding ubufs.
 123          * Protected by vq mutex. Writers must also take device mutex. */
 124         struct vhost_net_ubuf_ref *ubufs;
 125         struct ptr_ring *rx_ring;
 126         struct vhost_net_buf rxq;
 127         /* Batched XDP buffs */
 128         struct xdp_buff *xdp;
 129 };
 130
 131 struct vhost_net {
 132         struct vhost_dev dev;
 133         struct vhost_net_virtqueue vqs[VHOST_NET_VQ_MAX];
 134         struct vhost_poll poll[VHOST_NET_VQ_MAX];
 135         /* Number of TX recently submitted.
 136          * Protected by tx vq lock. */
 137         unsigned tx_packets;
 138         /* Number of times zerocopy TX recently failed.
 139          * Protected by tx vq lock. */
 140         unsigned tx_zcopy_err;
 141         /* Flush in progress. Protected by tx vq lock. */
 142         bool tx_flush;
 143         /* Private page frag */
 144         struct page_frag page_frag;
 145         /* Refcount bias of page frag */
 146         int refcnt_bias;
 147 };
 148
 149 static unsigned vhost_net_zcopy_mask __read_mostly;
 150
 151 static void *vhost_net_buf_get_ptr(struct vhost_net_buf *rxq)
 152 {
 153         if (rxq->tail != rxq->head)
 154                 return rxq->queue[rxq->head];
 155         else
 156                 return NULL;
 157 }
 158
 159 static int vhost_net_buf_get_size(struct vhost_net_buf *rxq)
 160 {
 161         return rxq->tail - rxq->head;
 162 }
 163
 164 static int vhost_net_buf_is_empty(struct vhost_net_buf *rxq)
 165 {
 166         return rxq->tail == rxq->head;
 167 }
 168
 169 static void *vhost_net_buf_consume(struct vhost_net_buf *rxq)
 170 {
 171         void *ret = vhost_net_buf_get_ptr(rxq);
 172         ++rxq->head;
 173         return ret;
 174 }
 175
 176 static int vhost_net_buf_produce(struct vhost_net_virtqueue *nvq)
 177 {
 178         struct vhost_net_buf *rxq = &nvq->rxq;
 179
 180         rxq->head = 0;
 181         rxq->tail = ptr_ring_consume_batched(nvq->rx_ring, rxq->queue,
 182                                               VHOST_NET_BATCH);
 183         return rxq->tail;
 184 }
 185
 186 static void vhost_net_buf_unproduce(struct vhost_net_virtqueue *nvq)
 187 {
 188         struct vhost_net_buf *rxq = &nvq->rxq;
 189
 190         if (nvq->rx_ring && !vhost_net_buf_is_empty(rxq)) {
 191                 ptr_ring_unconsume(nvq->rx_ring, rxq->queue + rxq->head,
 192                                    vhost_net_buf_get_size(rxq),
 193                                    tun_ptr_free);
 194                 rxq->head = rxq->tail = 0;
 195         }
 196 }
 197
 198 static int vhost_net_buf_peek_len(void *ptr)
 199 {
 200         if (tun_is_xdp_frame(ptr)) {
 201                 struct xdp_frame *xdpf = tun_ptr_to_xdp(ptr);
 202
 203                 return xdpf->len;
 204         }
 205
 206         return __skb_array_len_with_tag(ptr);
 207 }
 208
 209 static int vhost_net_buf_peek(struct vhost_net_virtqueue *nvq)
 210 {
 211         struct vhost_net_buf *rxq = &nvq->rxq;
 212
 213         if (!vhost_net_buf_is_empty(rxq))
 214                 goto out;
 215
 216         if (!vhost_net_buf_produce(nvq))
 217                 return 0;
 218
 219 out:
 220         return vhost_net_buf_peek_len(vhost_net_buf_get_ptr(rxq));
 221 }
 222
 223 static void vhost_net_buf_init(struct vhost_net_buf *rxq)
 224 {
 225         rxq->head = rxq->tail = 0;
 226 }
 227
 228 static void vhost_net_enable_zcopy(int vq)
 229 {
 230         vhost_net_zcopy_mask |= 0x1 << vq;
 231 }
 232
 233 static struct vhost_net_ubuf_ref *
 234 vhost_net_ubuf_alloc(struct vhost_virtqueue *vq, bool zcopy)
 235 {
 236         struct vhost_net_ubuf_ref *ubufs;
 237         /* No zero copy backend? Nothing to count. */
 238         if (!zcopy)
 239                 return NULL;
 240         ubufs = kmalloc(sizeof(*ubufs), GFP_KERNEL);
 241         if (!ubufs)
 242                 return ERR_PTR(-ENOMEM);
 243         atomic_set(&ubufs->refcount, 1);
 244         init_waitqueue_head(&ubufs->wait);
 245         ubufs->vq = vq;
 246         return ubufs;
 247 }
 248
 249 static int vhost_net_ubuf_put(struct vhost_net_ubuf_ref *ubufs)
 250 {
 251         int r = atomic_sub_return(1, &ubufs->refcount);
 252         if (unlikely(!r))
 253                 wake_up(&ubufs->wait);
 254         return r;
 255 }
 256
 257 static void vhost_net_ubuf_put_and_wait(struct vhost_net_ubuf_ref *ubufs)
 258 {
 259         vhost_net_ubuf_put(ubufs);
 260         wait_event(ubufs->wait, !atomic_read(&ubufs->refcount));
 261 }
 262
 263 static void vhost_net_ubuf_put_wait_and_free(struct vhost_net_ubuf_ref *ubufs)
 264 {
 265         vhost_net_ubuf_put_and_wait(ubufs);
 266         kfree(ubufs);
 267 }
 268
 269 static void vhost_net_clear_ubuf_info(struct vhost_net *n)
 270 {
 271         int i;
 272
 273         for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
 274                 kfree(n->vqs[i].ubuf_info);
 275                 n->vqs[i].ubuf_info = NULL;
 276         }
 277 }
 278
 279 static int vhost_net_set_ubuf_info(struct vhost_net *n)
 280 {
 281         bool zcopy;
 282         int i;
 283
 284         for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
 285                 zcopy = vhost_net_zcopy_mask & (0x1 << i);
 286                 if (!zcopy)
 287                         continue;
 288                 n->vqs[i].ubuf_info =
 289                         kmalloc_array(UIO_MAXIOV,
 290                                       sizeof(*n->vqs[i].ubuf_info),
 291                                       GFP_KERNEL);
 292                 if  (!n->vqs[i].ubuf_info)
 293                         goto err;
 294         }
 295         return 0;
 296
 297 err:
 298         vhost_net_clear_ubuf_info(n);
 299         return -ENOMEM;
 300 }
 301
 302 static void vhost_net_vq_reset(struct vhost_net *n)
 303 {
 304         int i;
 305
 306         vhost_net_clear_ubuf_info(n);
 307
 308         for (i = 0; i < VHOST_NET_VQ_MAX; i++) {
 309                 n->vqs[i].done_idx = 0;
 310                 n->vqs[i].upend_idx = 0;
 311                 n->vqs[i].ubufs = NULL;
 312                 n->vqs[i].vhost_hlen = 0;
 313                 n->vqs[i].sock_hlen = 0;
 314                 vhost_net_buf_init(&n->vqs[i].rxq);
 315         }
 316
 317 }
 318
 319 static void vhost_net_tx_packet(struct vhost_net *net)
 320 {
 321         ++net->tx_packets;
 322         if (net->tx_packets < 1024)
 323                 return;
 324         net->tx_packets = 0;
 325         net->tx_zcopy_err = 0;
 326 }
 327
 328 static void vhost_net_tx_err(struct vhost_net *net)
 329 {
 330         ++net->tx_zcopy_err;
 331 }
 332
 333 static bool vhost_net_tx_select_zcopy(struct vhost_net *net)
 334 {
 335         /* TX flush waits for outstanding DMAs to be done.
 336          * Don't start new DMAs.
 337          */
 338         return !net->tx_flush &&
 339                 net->tx_packets / 64 >= net->tx_zcopy_err;
 340 }
 341
 342 static bool vhost_sock_zcopy(struct socket *sock)
 343 {
 344         return unlikely(experimental_zcopytx) &&
 345                 sock_flag(sock->sk, SOCK_ZEROCOPY);
 346 }
 347
 348 static bool vhost_sock_xdp(struct socket *sock)
 349 {
 350         return sock_flag(sock->sk, SOCK_XDP);
 351 }
 352
 353 /* In case of DMA done not in order in lower device driver for some reason.
 354  * upend_idx is used to track end of used idx, done_idx is used to track head
 355  * of used idx. Once lower device DMA done contiguously, we will signal KVM
 356  * guest used idx.
 357  */
 358 static void vhost_zerocopy_signal_used(struct vhost_net *net,
 359                                        struct vhost_virtqueue *vq)
 360 {
 361         struct vhost_net_virtqueue *nvq =
 362                 container_of(vq, struct vhost_net_virtqueue, vq);
 363         int i, add;
 364         int j = 0;
 365
 366         for (i = nvq->done_idx; i != nvq->upend_idx; i = (i + 1) % UIO_MAXIOV) {
 367                 if (vq->heads[i].len == VHOST_DMA_FAILED_LEN)
 368                         vhost_net_tx_err(net);
 369                 if (VHOST_DMA_IS_DONE(vq->heads[i].len)) {
 370                         vq->heads[i].len = VHOST_DMA_CLEAR_LEN;
 371                         ++j;
 372                 } else
 373                         break;
 374         }
 375         while (j) {
 376                 add = min(UIO_MAXIOV - nvq->done_idx, j);
 377                 vhost_add_used_and_signal_n(vq->dev, vq,
 378                                             &vq->heads[nvq->done_idx], add);
 379                 nvq->done_idx = (nvq->done_idx + add) % UIO_MAXIOV;
 380                 j -= add;
 381         }
 382 }
 383
 384 static void vhost_zerocopy_callback(struct sk_buff *skb,
 385                                     struct ubuf_info *ubuf, bool success)
 386 {
 387         struct vhost_net_ubuf_ref *ubufs = ubuf->ctx;
 388         struct vhost_virtqueue *vq = ubufs->vq;
 389         int cnt;
 390
 391         rcu_read_lock_bh();
 392
 393         /* set len to mark this desc buffers done DMA */
 394         vq->heads[ubuf->desc].len = success ?
 395                 VHOST_DMA_DONE_LEN : VHOST_DMA_FAILED_LEN;
 396         cnt = vhost_net_ubuf_put(ubufs);
 397
 398         /*
 399          * Trigger polling thread if guest stopped submitting new buffers:
 400          * in this case, the refcount after decrement will eventually reach 1.
 401          * We also trigger polling periodically after each 16 packets
 402          * (the value 16 here is more or less arbitrary, it's tuned to trigger
 403          * less than 10% of times).
 404          */
 405         if (cnt <= 1 || !(cnt % 16))
 406                 vhost_poll_queue(&vq->poll);
 407
 408         rcu_read_unlock_bh();
 409 }
 410
 411 static inline unsigned long busy_clock(void)
 412 {
 413         return local_clock() >> 10;
 414 }
 415
 416 static bool vhost_can_busy_poll(unsigned long endtime)
 417 {
 418         return likely(!need_resched() && !time_after(busy_clock(), endtime) &&
 419                       !signal_pending(current));
 420 }
 421
 422 static void vhost_net_disable_vq(struct vhost_net *n,
 423                                  struct vhost_virtqueue *vq)
 424 {
 425         struct vhost_net_virtqueue *nvq =
 426                 container_of(vq, struct vhost_net_virtqueue, vq);
 427         struct vhost_poll *poll = n->poll + (nvq - n->vqs);
 428         if (!vhost_vq_get_backend(vq))
 429                 return;
 430         vhost_poll_stop(poll);
 431 }
 432
 433 static int vhost_net_enable_vq(struct vhost_net *n,
 434                                 struct vhost_virtqueue *vq)
 435 {
 436         struct vhost_net_virtqueue *nvq =
 437                 container_of(vq, struct vhost_net_virtqueue, vq);
 438         struct vhost_poll *poll = n->poll + (nvq - n->vqs);
 439         struct socket *sock;
 440
 441         sock = vhost_vq_get_backend(vq);
 442         if (!sock)
 443                 return 0;
 444
 445         return vhost_poll_start(poll, sock->file);
 446 }
 447
 448 static void vhost_net_signal_used(struct vhost_net_virtqueue *nvq)
 449 {
 450         struct vhost_virtqueue *vq = &nvq->vq;
 451         struct vhost_dev *dev = vq->dev;
 452
 453         if (!nvq->done_idx)
 454                 return;
 455
 456         vhost_add_used_and_signal_n(dev, vq, vq->heads, nvq->done_idx);
 457         nvq->done_idx = 0;
 458 }
 459
 460 static void vhost_tx_batch(struct vhost_net *net,
 461                            struct vhost_net_virtqueue *nvq,
 462                            struct socket *sock,
 463                            struct msghdr *msghdr)
 464 {
 465         struct tun_msg_ctl ctl = {
 466                 .type = TUN_MSG_PTR,
 467                 .num = nvq->batched_xdp,
 468                 .ptr = nvq->xdp,
 469         };
 470         int err;
 471
 472         if (nvq->batched_xdp == 0)
 473                 goto signal_used;
 474
 475         msghdr->msg_control = &ctl;
 476         err = sock->ops->sendmsg(sock, msghdr, 0);
 477         if (unlikely(err < 0)) {
 478                 vq_err(&nvq->vq, "Fail to batch sending packets\n");
 479                 return;
 480         }
 481
 482 signal_used:
 483         vhost_net_signal_used(nvq);
 484         nvq->batched_xdp = 0;
 485 }
 486
 487 static int sock_has_rx_data(struct socket *sock)
 488 {
 489         if (unlikely(!sock))
 490                 return 0;
 491
 492         if (sock->ops->peek_len)
 493                 return sock->ops->peek_len(sock);
 494
 495         return skb_queue_empty(&sock->sk->sk_receive_queue);
 496 }
 497
 498 static void vhost_net_busy_poll_try_queue(struct vhost_net *net,
 499                                           struct vhost_virtqueue *vq)
 500 {
 501         if (!vhost_vq_avail_empty(&net->dev, vq)) {
 502                 vhost_poll_queue(&vq->poll);
 503         } else if (unlikely(vhost_enable_notify(&net->dev, vq))) {
 504                 vhost_disable_notify(&net->dev, vq);
 505                 vhost_poll_queue(&vq->poll);
 506         }
 507 }
 508
 509 static void vhost_net_busy_poll(struct vhost_net *net,
 510                                 struct vhost_virtqueue *rvq,
 511                                 struct vhost_virtqueue *tvq,
 512                                 bool *busyloop_intr,
 513                                 bool poll_rx)
 514 {
 515         unsigned long busyloop_timeout;
 516         unsigned long endtime;
 517         struct socket *sock;
 518         struct vhost_virtqueue *vq = poll_rx ? tvq : rvq;
 519
 520         /* Try to hold the vq mutex of the paired virtqueue. We can't
 521          * use mutex_lock() here since we could not guarantee a
 522          * consistenet lock ordering.
 523          */
 524         if (!mutex_trylock(&vq->mutex))
 525                 return;
 526
 527         vhost_disable_notify(&net->dev, vq);
 528         sock = vhost_vq_get_backend(rvq);
 529
 530         busyloop_timeout = poll_rx ? rvq->busyloop_timeout:
 531                                      tvq->busyloop_timeout;
 532
 533         preempt_disable();
 534         endtime = busy_clock() + busyloop_timeout;
 535
 536         while (vhost_can_busy_poll(endtime)) {
 537                 if (vhost_has_work(&net->dev)) {
 538                         *busyloop_intr = true;
 539                         break;
 540                 }
 541
 542                 if ((sock_has_rx_data(sock) &&
 543                      !vhost_vq_avail_empty(&net->dev, rvq)) ||
 544                     !vhost_vq_avail_empty(&net->dev, tvq))
 545                         break;
 546
 547                 cpu_relax();
 548         }
 549
 550         preempt_enable();
 551
 552         if (poll_rx || sock_has_rx_data(sock))
 553                 vhost_net_busy_poll_try_queue(net, vq);
 554         else if (!poll_rx) /* On tx here, sock has no rx data. */
 555                 vhost_enable_notify(&net->dev, rvq);
 556
 557         mutex_unlock(&vq->mutex);
 558 }
 559
 560 static int vhost_net_tx_get_vq_desc(struct vhost_net *net,
 561                                     struct vhost_net_virtqueue *tnvq,
 562                                     unsigned int *out_num, unsigned int *in_num,
 563                                     struct msghdr *msghdr, bool *busyloop_intr)
 564 {
 565         struct vhost_net_virtqueue *rnvq = &net->vqs[VHOST_NET_VQ_RX];
 566         struct vhost_virtqueue *rvq = &rnvq->vq;
 567         struct vhost_virtqueue *tvq = &tnvq->vq;
 568
 569         int r = vhost_get_vq_desc(tvq, tvq->iov, ARRAY_SIZE(tvq->iov),
 570                                   out_num, in_num, NULL, NULL);
 571
 572         if (r == tvq->num && tvq->busyloop_timeout) {
 573                 /* Flush batched packets first */
 574                 if (!vhost_sock_zcopy(vhost_vq_get_backend(tvq)))
 575                         vhost_tx_batch(net, tnvq,
 576                                        vhost_vq_get_backend(tvq),
 577                                        msghdr);
 578
 579                 vhost_net_busy_poll(net, rvq, tvq, busyloop_intr, false);
 580
 581                 r = vhost_get_vq_desc(tvq, tvq->iov, ARRAY_SIZE(tvq->iov),
 582                                       out_num, in_num, NULL, NULL);
 583         }
 584
 585         return r;
 586 }
 587
 588 static bool vhost_exceeds_maxpend(struct vhost_net *net)
 589 {
 590         struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
 591         struct vhost_virtqueue *vq = &nvq->vq;
 592
 593         return (nvq->upend_idx + UIO_MAXIOV - nvq->done_idx) % UIO_MAXIOV >
 594                min_t(unsigned int, VHOST_MAX_PEND, vq->num >> 2);
 595 }
 596
 597 static size_t init_iov_iter(struct vhost_virtqueue *vq, struct iov_iter *iter,
 598                             size_t hdr_size, int out)
 599 {
 600         /* Skip header. TODO: support TSO. */
 601         size_t len = iov_length(vq->iov, out);
 602
 603         iov_iter_init(iter, WRITE, vq->iov, out, len);
 604         iov_iter_advance(iter, hdr_size);
 605
 606         return iov_iter_count(iter);
 607 }
 608
 609 static int get_tx_bufs(struct vhost_net *net,
 610                        struct vhost_net_virtqueue *nvq,
 611                        struct msghdr *msg,
 612                        unsigned int *out, unsigned int *in,
 613                        size_t *len, bool *busyloop_intr)
 614 {
 615         struct vhost_virtqueue *vq = &nvq->vq;
 616         int ret;
 617
 618         ret = vhost_net_tx_get_vq_desc(net, nvq, out, in, msg, busyloop_intr);
 619
 620         if (ret < 0 || ret == vq->num)
 621                 return ret;
 622
 623         if (*in) {
 624                 vq_err(vq, "Unexpected descriptor format for TX: out %d, int %d\n",
 625                         *out, *in);
 626                 return -EFAULT;
 627         }
 628
 629         /* Sanity check */
 630         *len = init_iov_iter(vq, &msg->msg_iter, nvq->vhost_hlen, *out);
 631         if (*len == 0) {
 632                 vq_err(vq, "Unexpected header len for TX: %zd expected %zd\n",
 633                         *len, nvq->vhost_hlen);
 634                 return -EFAULT;
 635         }
 636
 637         return ret;
 638 }
 639
 640 static bool tx_can_batch(struct vhost_virtqueue *vq, size_t total_len)
 641 {
 642         return total_len < VHOST_NET_WEIGHT &&
 643                !vhost_vq_avail_empty(vq->dev, vq);
 644 }
 645
 646 #define SKB_FRAG_PAGE_ORDER     get_order(32768)
 647
 648 static bool vhost_net_page_frag_refill(struct vhost_net *net, unsigned int sz,
 649                                        struct page_frag *pfrag, gfp_t gfp)
 650 {
 651         if (pfrag->page) {
 652                 if (pfrag->offset + sz <= pfrag->size)
 653                         return true;
 654                 __page_frag_cache_drain(pfrag->page, net->refcnt_bias);
 655         }
 656
 657         pfrag->offset = 0;
 658         net->refcnt_bias = 0;
 659         if (SKB_FRAG_PAGE_ORDER) {
 660                 /* Avoid direct reclaim but allow kswapd to wake */
 661                 pfrag->page = alloc_pages((gfp & ~__GFP_DIRECT_RECLAIM) |
 662                                           __GFP_COMP | __GFP_NOWARN |
 663                                           __GFP_NORETRY,
 664                                           SKB_FRAG_PAGE_ORDER);
 665                 if (likely(pfrag->page)) {
 666                         pfrag->size = PAGE_SIZE << SKB_FRAG_PAGE_ORDER;
 667                         goto done;
 668                 }
 669         }
 670         pfrag->page = alloc_page(gfp);
 671         if (likely(pfrag->page)) {
 672                 pfrag->size = PAGE_SIZE;
 673                 goto done;
 674         }
 675         return false;
 676
 677 done:
 678         net->refcnt_bias = USHRT_MAX;
 679         page_ref_add(pfrag->page, USHRT_MAX - 1);
 680         return true;
 681 }
 682
 683 #define VHOST_NET_RX_PAD (NET_IP_ALIGN + NET_SKB_PAD)
 684
 685 static int vhost_net_build_xdp(struct vhost_net_virtqueue *nvq,
 686                                struct iov_iter *from)
 687 {
 688         struct vhost_virtqueue *vq = &nvq->vq;
 689         struct vhost_net *net = container_of(vq->dev, struct vhost_net,
 690                                              dev);
 691         struct socket *sock = vhost_vq_get_backend(vq);
 692         struct page_frag *alloc_frag = &net->page_frag;
 693         struct virtio_net_hdr *gso;
 694         struct xdp_buff *xdp = &nvq->xdp[nvq->batched_xdp];
 695         struct tun_xdp_hdr *hdr;
 696         size_t len = iov_iter_count(from);
 697         int headroom = vhost_sock_xdp(sock) ? XDP_PACKET_HEADROOM : 0;
 698         int buflen = SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
 699         int pad = SKB_DATA_ALIGN(VHOST_NET_RX_PAD + headroom + nvq->sock_hlen);
 700         int sock_hlen = nvq->sock_hlen;
 701         void *buf;
 702         int copied;
 703
 704         if (unlikely(len < nvq->sock_hlen))
 705                 return -EFAULT;
 706
 707         if (SKB_DATA_ALIGN(len + pad) +
 708             SKB_DATA_ALIGN(sizeof(struct skb_shared_info)) > PAGE_SIZE)
 709                 return -ENOSPC;
 710
 711         buflen += SKB_DATA_ALIGN(len + pad);
 712         alloc_frag->offset = ALIGN((u64)alloc_frag->offset, SMP_CACHE_BYTES);
 713         if (unlikely(!vhost_net_page_frag_refill(net, buflen,
 714                                                  alloc_frag, GFP_KERNEL)))
 715                 return -ENOMEM;
 716
 717         buf = (char *)page_address(alloc_frag->page) + alloc_frag->offset;
 718         copied = copy_page_from_iter(alloc_frag->page,
 719                                      alloc_frag->offset +
 720                                      offsetof(struct tun_xdp_hdr, gso),
 721                                      sock_hlen, from);
 722         if (copied != sock_hlen)
 723                 return -EFAULT;
 724
 725         hdr = buf;
 726         gso = &hdr->gso;
 727
 728         if ((gso->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) &&
 729             vhost16_to_cpu(vq, gso->csum_start) +
 730             vhost16_to_cpu(vq, gso->csum_offset) + 2 >
 731             vhost16_to_cpu(vq, gso->hdr_len)) {
 732                 gso->hdr_len = cpu_to_vhost16(vq,
 733                                vhost16_to_cpu(vq, gso->csum_start) +
 734                                vhost16_to_cpu(vq, gso->csum_offset) + 2);
 735
 736                 if (vhost16_to_cpu(vq, gso->hdr_len) > len)
 737                         return -EINVAL;
 738         }
 739
 740         len -= sock_hlen;
 741         copied = copy_page_from_iter(alloc_frag->page,
 742                                      alloc_frag->offset + pad,
 743                                      len, from);
 744         if (copied != len)
 745                 return -EFAULT;
 746
 747         xdp_init_buff(xdp, buflen, NULL);
 748         xdp_prepare_buff(xdp, buf, pad, len, true);
 749         hdr->buflen = buflen;
 750
 751         --net->refcnt_bias;
 752         alloc_frag->offset += buflen;
 753
 754         ++nvq->batched_xdp;
 755
 756         return 0;
 757 }
 758
 759 static void handle_tx_copy(struct vhost_net *net, struct socket *sock)
 760 {
 761         struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
 762         struct vhost_virtqueue *vq = &nvq->vq;
 763         unsigned out, in;
 764         int head;
 765         struct msghdr msg = {
 766                 .msg_name = NULL,
 767                 .msg_namelen = 0,
 768                 .msg_control = NULL,
 769                 .msg_controllen = 0,
 770                 .msg_flags = MSG_DONTWAIT,
 771         };
 772         size_t len, total_len = 0;
 773         int err;
 774         int sent_pkts = 0;
 775         bool sock_can_batch = (sock->sk->sk_sndbuf == INT_MAX);
 776
 777         do {
 778                 bool busyloop_intr = false;
 779
 780                 if (nvq->done_idx == VHOST_NET_BATCH)
 781                         vhost_tx_batch(net, nvq, sock, &msg);
 782
 783                 head = get_tx_bufs(net, nvq, &msg, &out, &in, &len,
 784                                    &busyloop_intr);
 785                 /* On error, stop handling until the next kick. */
 786                 if (unlikely(head < 0))
 787                         break;
 788                 /* Nothing new?  Wait for eventfd to tell us they refilled. */
 789                 if (head == vq->num) {
 790                         if (unlikely(busyloop_intr)) {
 791                                 vhost_poll_queue(&vq->poll);
 792                         } else if (unlikely(vhost_enable_notify(&net->dev,
 793                                                                 vq))) {
 794                                 vhost_disable_notify(&net->dev, vq);
 795                                 continue;
 796                         }
 797                         break;
 798                 }
 799
 800                 total_len += len;
 801
 802                 /* For simplicity, TX batching is only enabled if
 803                  * sndbuf is unlimited.
 804                  */
 805                 if (sock_can_batch) {
 806                         err = vhost_net_build_xdp(nvq, &msg.msg_iter);
 807                         if (!err) {
 808                                 goto done;
 809                         } else if (unlikely(err != -ENOSPC)) {
 810                                 vhost_tx_batch(net, nvq, sock, &msg);
 811                                 vhost_discard_vq_desc(vq, 1);
 812                                 vhost_net_enable_vq(net, vq);
 813                                 break;
 814                         }
 815
 816                         /* We can't build XDP buff, go for single
 817                          * packet path but let's flush batched
 818                          * packets.
 819                          */
 820                         vhost_tx_batch(net, nvq, sock, &msg);
 821                         msg.msg_control = NULL;
 822                 } else {
 823                         if (tx_can_batch(vq, total_len))
 824                                 msg.msg_flags |= MSG_MORE;
 825                         else
 826                                 msg.msg_flags &= ~MSG_MORE;
 827                 }
 828
 829                 err = sock->ops->sendmsg(sock, &msg, len);
 830                 if (unlikely(err < 0)) {
 831                         if (err == -EAGAIN || err == -ENOMEM || err == -ENOBUFS) {
 832                                 vhost_discard_vq_desc(vq, 1);
 833                                 vhost_net_enable_vq(net, vq);
 834                                 break;
 835                         }
 836                         pr_debug("Fail to send packet: err %d", err);
 837                 } else if (unlikely(err != len))
 838                         pr_debug("Truncated TX packet: len %d != %zd\n",
 839                                  err, len);
 840 done:
 841                 vq->heads[nvq->done_idx].id = cpu_to_vhost32(vq, head);
 842                 vq->heads[nvq->done_idx].len = 0;
 843                 ++nvq->done_idx;
 844         } while (likely(!vhost_exceeds_weight(vq, ++sent_pkts, total_len)));
 845
 846         vhost_tx_batch(net, nvq, sock, &msg);
 847 }
 848
 849 static void handle_tx_zerocopy(struct vhost_net *net, struct socket *sock)
 850 {
 851         struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
 852         struct vhost_virtqueue *vq = &nvq->vq;
 853         unsigned out, in;
 854         int head;
 855         struct msghdr msg = {
 856                 .msg_name = NULL,
 857                 .msg_namelen = 0,
 858                 .msg_control = NULL,
 859                 .msg_controllen = 0,
 860                 .msg_flags = MSG_DONTWAIT,
 861         };
 862         struct tun_msg_ctl ctl;
 863         size_t len, total_len = 0;
 864         int err;
 865         struct vhost_net_ubuf_ref *ubufs;
 866         struct ubuf_info *ubuf;
 867         bool zcopy_used;
 868         int sent_pkts = 0;
 869
 870         do {
 871                 bool busyloop_intr;
 872
 873                 /* Release DMAs done buffers first */
 874                 vhost_zerocopy_signal_used(net, vq);
 875
 876                 busyloop_intr = false;
 877                 head = get_tx_bufs(net, nvq, &msg, &out, &in, &len,
 878                                    &busyloop_intr);
 879                 /* On error, stop handling until the next kick. */
 880                 if (unlikely(head < 0))
 881                         break;
 882                 /* Nothing new?  Wait for eventfd to tell us they refilled. */
 883                 if (head == vq->num) {
 884                         if (unlikely(busyloop_intr)) {
 885                                 vhost_poll_queue(&vq->poll);
 886                         } else if (unlikely(vhost_enable_notify(&net->dev, vq))) {
 887                                 vhost_disable_notify(&net->dev, vq);
 888                                 continue;
 889                         }
 890                         break;
 891                 }
 892
 893                 zcopy_used = len >= VHOST_GOODCOPY_LEN
 894                              && !vhost_exceeds_maxpend(net)
 895                              && vhost_net_tx_select_zcopy(net);
 896
 897                 /* use msg_control to pass vhost zerocopy ubuf info to skb */
 898                 if (zcopy_used) {
 899                         ubuf = nvq->ubuf_info + nvq->upend_idx;
 900                         vq->heads[nvq->upend_idx].id = cpu_to_vhost32(vq, head);
 901                         vq->heads[nvq->upend_idx].len = VHOST_DMA_IN_PROGRESS;
 902                         ubuf->callback = vhost_zerocopy_callback;
 903                         ubuf->ctx = nvq->ubufs;
 904                         ubuf->desc = nvq->upend_idx;
 905                         ubuf->flags = SKBFL_ZEROCOPY_FRAG;
 906                         refcount_set(&ubuf->refcnt, 1);
 907                         msg.msg_control = &ctl;
 908                         ctl.type = TUN_MSG_UBUF;
 909                         ctl.ptr = ubuf;
 910                         msg.msg_controllen = sizeof(ctl);
 911                         ubufs = nvq->ubufs;
 912                         atomic_inc(&ubufs->refcount);
 913                         nvq->upend_idx = (nvq->upend_idx + 1) % UIO_MAXIOV;
 914                 } else {
 915                         msg.msg_control = NULL;
 916                         ubufs = NULL;
 917                 }
 918                 total_len += len;
 919                 if (tx_can_batch(vq, total_len) &&
 920                     likely(!vhost_exceeds_maxpend(net))) {
 921                         msg.msg_flags |= MSG_MORE;
 922                 } else {
 923                         msg.msg_flags &= ~MSG_MORE;
 924                 }
 925
 926                 err = sock->ops->sendmsg(sock, &msg, len);
 927                 if (unlikely(err < 0)) {
 928                         if (zcopy_used) {
 929                                 if (vq->heads[ubuf->desc].len == VHOST_DMA_IN_PROGRESS)
 930                                         vhost_net_ubuf_put(ubufs);
 931                                 nvq->upend_idx = ((unsigned)nvq->upend_idx - 1)
 932                                         % UIO_MAXIOV;
 933                         }
 934                         if (err == -EAGAIN || err == -ENOMEM || err == -ENOBUFS) {
 935                                 vhost_discard_vq_desc(vq, 1);
 936                                 vhost_net_enable_vq(net, vq);
 937                                 break;
 938                         }
 939                         pr_debug("Fail to send packet: err %d", err);
 940                 } else if (unlikely(err != len))
 941                         pr_debug("Truncated TX packet: "
 942                                  " len %d != %zd\n", err, len);
 943                 if (!zcopy_used)
 944                         vhost_add_used_and_signal(&net->dev, vq, head, 0);
 945                 else
 946                         vhost_zerocopy_signal_used(net, vq);
 947                 vhost_net_tx_packet(net);
 948         } while (likely(!vhost_exceeds_weight(vq, ++sent_pkts, total_len)));
 949 }
 950
 951 /* Expects to be always run from workqueue - which acts as
 952  * read-size critical section for our kind of RCU. */
 953 static void handle_tx(struct vhost_net *net)
 954 {
 955         struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
 956         struct vhost_virtqueue *vq = &nvq->vq;
 957         struct socket *sock;
 958
 959         mutex_lock_nested(&vq->mutex, VHOST_NET_VQ_TX);
 960         sock = vhost_vq_get_backend(vq);
 961         if (!sock)
 962                 goto out;
 963
 964         if (!vq_meta_prefetch(vq))
 965                 goto out;
 966
 967         vhost_disable_notify(&net->dev, vq);
 968         vhost_net_disable_vq(net, vq);
 969
 970         if (vhost_sock_zcopy(sock))
 971                 handle_tx_zerocopy(net, sock);
 972         else
 973                 handle_tx_copy(net, sock);
 974
 975 out:
 976         mutex_unlock(&vq->mutex);
 977 }
 978
 979 static int peek_head_len(struct vhost_net_virtqueue *rvq, struct sock *sk)
 980 {
 981         struct sk_buff *head;
 982         int len = 0;
 983         unsigned long flags;
 984
 985         if (rvq->rx_ring)
 986                 return vhost_net_buf_peek(rvq);
 987
 988         spin_lock_irqsave(&sk->sk_receive_queue.lock, flags);
 989         head = skb_peek(&sk->sk_receive_queue);
 990         if (likely(head)) {
 991                 len = head->len;
 992                 if (skb_vlan_tag_present(head))
 993                         len += VLAN_HLEN;
 994         }
 995
 996         spin_unlock_irqrestore(&sk->sk_receive_queue.lock, flags);
 997         return len;
 998 }
 999
1000 static int vhost_net_rx_peek_head_len(struct vhost_net *net, struct sock *sk,
1001                                       bool *busyloop_intr)
1002 {
1003         struct vhost_net_virtqueue *rnvq = &net->vqs[VHOST_NET_VQ_RX];
1004         struct vhost_net_virtqueue *tnvq = &net->vqs[VHOST_NET_VQ_TX];
1005         struct vhost_virtqueue *rvq = &rnvq->vq;
1006         struct vhost_virtqueue *tvq = &tnvq->vq;
1007         int len = peek_head_len(rnvq, sk);
1008
1009         if (!len && rvq->busyloop_timeout) {
1010                 /* Flush batched heads first */
1011                 vhost_net_signal_used(rnvq);
1012                 /* Both tx vq and rx socket were polled here */
1013                 vhost_net_busy_poll(net, rvq, tvq, busyloop_intr, true);
1014
1015                 len = peek_head_len(rnvq, sk);
1016         }
1017
1018         return len;
1019 }
1020
1021 /* This is a multi-buffer version of vhost_get_desc, that works if
1022  *      vq has read descriptors only.
1023  * @vq          - the relevant virtqueue
1024  * @datalen     - data length we'll be reading
1025  * @iovcount    - returned count of io vectors we fill
1026  * @log         - vhost log
1027  * @log_num     - log offset
1028  * @quota       - headcount quota, 1 for big buffer
1029  *      returns number of buffer heads allocated, negative on error
1030  */
1031 static int get_rx_bufs(struct vhost_virtqueue *vq,
1032                        struct vring_used_elem *heads,
1033                        int datalen,
1034                        unsigned *iovcount,
1035                        struct vhost_log *log,
1036                        unsigned *log_num,
1037                        unsigned int quota)
1038 {
1039         unsigned int out, in;
1040         int seg = 0;
1041         int headcount = 0;
1042         unsigned d;
1043         int r, nlogs = 0;
1044         /* len is always initialized before use since we are always called with
1045          * datalen > 0.
1046          */
1047         u32 len;
1048
1049         while (datalen > 0 && headcount < quota) {
1050                 if (unlikely(seg >= UIO_MAXIOV)) {
1051                         r = -ENOBUFS;
1052                         goto err;
1053                 }
1054                 r = vhost_get_vq_desc(vq, vq->iov + seg,
1055                                       ARRAY_SIZE(vq->iov) - seg, &out,
1056                                       &in, log, log_num);
1057                 if (unlikely(r < 0))
1058                         goto err;
1059
1060                 d = r;
1061                 if (d == vq->num) {
1062                         r = 0;
1063                         goto err;
1064                 }
1065                 if (unlikely(out || in <= 0)) {
1066                         vq_err(vq, "unexpected descriptor format for RX: "
1067                                 "out %d, in %d\n", out, in);
1068                         r = -EINVAL;
1069                         goto err;
1070                 }
1071                 if (unlikely(log)) {
1072                         nlogs += *log_num;
1073                         log += *log_num;
1074                 }
1075                 heads[headcount].id = cpu_to_vhost32(vq, d);
1076                 len = iov_length(vq->iov + seg, in);
1077                 heads[headcount].len = cpu_to_vhost32(vq, len);
1078                 datalen -= len;
1079                 ++headcount;
1080                 seg += in;
1081         }
1082         heads[headcount - 1].len = cpu_to_vhost32(vq, len + datalen);
1083         *iovcount = seg;
1084         if (unlikely(log))
1085                 *log_num = nlogs;
1086
1087         /* Detect overrun */
1088         if (unlikely(datalen > 0)) {
1089                 r = UIO_MAXIOV + 1;
1090                 goto err;
1091         }
1092         return headcount;
1093 err:
1094         vhost_discard_vq_desc(vq, headcount);
1095         return r;
1096 }
1097
1098 /* Expects to be always run from workqueue - which acts as
1099  * read-size critical section for our kind of RCU. */
1100 static void handle_rx(struct vhost_net *net)
1101 {
1102         struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_RX];
1103         struct vhost_virtqueue *vq = &nvq->vq;
1104         unsigned in, log;
1105         struct vhost_log *vq_log;
1106         struct msghdr msg = {
1107                 .msg_name = NULL,
1108                 .msg_namelen = 0,
1109                 .msg_control = NULL, /* FIXME: get and handle RX aux data. */
1110                 .msg_controllen = 0,
1111                 .msg_flags = MSG_DONTWAIT,
1112         };
1113         struct virtio_net_hdr hdr = {
1114                 .flags = 0,
1115                 .gso_type = VIRTIO_NET_HDR_GSO_NONE
1116         };
1117         size_t total_len = 0;
1118         int err, mergeable;
1119         s16 headcount;
1120         size_t vhost_hlen, sock_hlen;
1121         size_t vhost_len, sock_len;
1122         bool busyloop_intr = false;
1123         struct socket *sock;
1124         struct iov_iter fixup;
1125         __virtio16 num_buffers;
1126         int recv_pkts = 0;
1127
1128         mutex_lock_nested(&vq->mutex, VHOST_NET_VQ_RX);
1129         sock = vhost_vq_get_backend(vq);
1130         if (!sock)
1131                 goto out;
1132
1133         if (!vq_meta_prefetch(vq))
1134                 goto out;
1135
1136         vhost_disable_notify(&net->dev, vq);
1137         vhost_net_disable_vq(net, vq);
1138
1139         vhost_hlen = nvq->vhost_hlen;
1140         sock_hlen = nvq->sock_hlen;
1141
1142         vq_log = unlikely(vhost_has_feature(vq, VHOST_F_LOG_ALL)) ?
1143                 vq->log : NULL;
1144         mergeable = vhost_has_feature(vq, VIRTIO_NET_F_MRG_RXBUF);
1145
1146         do {
1147                 sock_len = vhost_net_rx_peek_head_len(net, sock->sk,
1148                                                       &busyloop_intr);
1149                 if (!sock_len)
1150                         break;
1151                 sock_len += sock_hlen;
1152                 vhost_len = sock_len + vhost_hlen;
1153                 headcount = get_rx_bufs(vq, vq->heads + nvq->done_idx,
1154                                         vhost_len, &in, vq_log, &log,
1155                                         likely(mergeable) ? UIO_MAXIOV : 1);
1156                 /* On error, stop handling until the next kick. */
1157                 if (unlikely(headcount < 0))
1158                         goto out;
1159                 /* OK, now we need to know about added descriptors. */
1160                 if (!headcount) {
1161                         if (unlikely(busyloop_intr)) {
1162                                 vhost_poll_queue(&vq->poll);
1163                         } else if (unlikely(vhost_enable_notify(&net->dev, vq))) {
1164                                 /* They have slipped one in as we were
1165                                  * doing that: check again. */
1166                                 vhost_disable_notify(&net->dev, vq);
1167                                 continue;
1168                         }
1169                         /* Nothing new?  Wait for eventfd to tell us
1170                          * they refilled. */
1171                         goto out;
1172                 }
1173                 busyloop_intr = false;
1174                 if (nvq->rx_ring)
1175                         msg.msg_control = vhost_net_buf_consume(&nvq->rxq);
1176                 /* On overrun, truncate and discard */
1177                 if (unlikely(headcount > UIO_MAXIOV)) {
1178                         iov_iter_init(&msg.msg_iter, READ, vq->iov, 1, 1);
1179                         err = sock->ops->recvmsg(sock, &msg,
1180                                                  1, MSG_DONTWAIT | MSG_TRUNC);
1181                         pr_debug("Discarded rx packet: len %zd\n", sock_len);
1182                         continue;
1183                 }
1184                 /* We don't need to be notified again. */
1185                 iov_iter_init(&msg.msg_iter, READ, vq->iov, in, vhost_len);
1186                 fixup = msg.msg_iter;
1187                 if (unlikely((vhost_hlen))) {
1188                         /* We will supply the header ourselves
1189                          * TODO: support TSO.
1190                          */
1191                         iov_iter_advance(&msg.msg_iter, vhost_hlen);
1192                 }
1193                 err = sock->ops->recvmsg(sock, &msg,
1194                                          sock_len, MSG_DONTWAIT | MSG_TRUNC);
1195                 /* Userspace might have consumed the packet meanwhile:
1196                  * it's not supposed to do this usually, but might be hard
1197                  * to prevent. Discard data we got (if any) and keep going. */
1198                 if (unlikely(err != sock_len)) {
1199                         pr_debug("Discarded rx packet: "
1200                                  " len %d, expected %zd\n", err, sock_len);
1201                         vhost_discard_vq_desc(vq, headcount);
1202                         continue;
1203                 }
1204                 /* Supply virtio_net_hdr if VHOST_NET_F_VIRTIO_NET_HDR */
1205                 if (unlikely(vhost_hlen)) {
1206                         if (copy_to_iter(&hdr, sizeof(hdr),
1207                                          &fixup) != sizeof(hdr)) {
1208                                 vq_err(vq, "Unable to write vnet_hdr "
1209                                        "at addr %p\n", vq->iov->iov_base);
1210                                 goto out;
1211                         }
1212                 } else {
1213                         /* Header came from socket; we'll need to patch
1214                          * ->num_buffers over if VIRTIO_NET_F_MRG_RXBUF
1215                          */
1216                         iov_iter_advance(&fixup, sizeof(hdr));
1217                 }
1218                 /* TODO: Should check and handle checksum. */
1219
1220                 num_buffers = cpu_to_vhost16(vq, headcount);
1221                 if (likely(mergeable) &&
1222                     copy_to_iter(&num_buffers, sizeof num_buffers,
1223                                  &fixup) != sizeof num_buffers) {
1224                         vq_err(vq, "Failed num_buffers write");
1225                         vhost_discard_vq_desc(vq, headcount);
1226                         goto out;
1227                 }
1228                 nvq->done_idx += headcount;
1229                 if (nvq->done_idx > VHOST_NET_BATCH)
1230                         vhost_net_signal_used(nvq);
1231                 if (unlikely(vq_log))
1232                         vhost_log_write(vq, vq_log, log, vhost_len,
1233                                         vq->iov, in);
1234                 total_len += vhost_len;
1235         } while (likely(!vhost_exceeds_weight(vq, ++recv_pkts, total_len)));
1236
1237         if (unlikely(busyloop_intr))
1238                 vhost_poll_queue(&vq->poll);
1239         else if (!sock_len)
1240                 vhost_net_enable_vq(net, vq);
1241 out:
1242         vhost_net_signal_used(nvq);
1243         mutex_unlock(&vq->mutex);
1244 }
1245
1246 static void handle_tx_kick(struct vhost_work *work)
1247 {
1248         struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
1249                                                   poll.work);
1250         struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev);
1251
1252         handle_tx(net);
1253 }
1254
1255 static void handle_rx_kick(struct vhost_work *work)
1256 {
1257         struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
1258                                                   poll.work);
1259         struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev);
1260
1261         handle_rx(net);
1262 }
1263
1264 static void handle_tx_net(struct vhost_work *work)
1265 {
1266         struct vhost_net *net = container_of(work, struct vhost_net,
1267                                              poll[VHOST_NET_VQ_TX].work);
1268         handle_tx(net);
1269 }
1270
1271 static void handle_rx_net(struct vhost_work *work)
1272 {
1273         struct vhost_net *net = container_of(work, struct vhost_net,
1274                                              poll[VHOST_NET_VQ_RX].work);
1275         handle_rx(net);
1276 }
1277
1278 static int vhost_net_open(struct inode *inode, struct file *f)
1279 {
1280         struct vhost_net *n;
1281         struct vhost_dev *dev;
1282         struct vhost_virtqueue **vqs;
1283         void **queue;
1284         struct xdp_buff *xdp;
1285         int i;
1286
1287         n = kvmalloc(sizeof *n, GFP_KERNEL | __GFP_RETRY_MAYFAIL);
1288         if (!n)
1289                 return -ENOMEM;
1290         vqs = kmalloc_array(VHOST_NET_VQ_MAX, sizeof(*vqs), GFP_KERNEL);
1291         if (!vqs) {
1292                 kvfree(n);
1293                 return -ENOMEM;
1294         }
1295
1296         queue = kmalloc_array(VHOST_NET_BATCH, sizeof(void *),
1297                               GFP_KERNEL);
1298         if (!queue) {
1299                 kfree(vqs);
1300                 kvfree(n);
1301                 return -ENOMEM;
1302         }
1303         n->vqs[VHOST_NET_VQ_RX].rxq.queue = queue;
1304
1305         xdp = kmalloc_array(VHOST_NET_BATCH, sizeof(*xdp), GFP_KERNEL);
1306         if (!xdp) {
1307                 kfree(vqs);
1308                 kvfree(n);
1309                 kfree(queue);
1310                 return -ENOMEM;
1311         }
1312         n->vqs[VHOST_NET_VQ_TX].xdp = xdp;
1313
1314         dev = &n->dev;
1315         vqs[VHOST_NET_VQ_TX] = &n->vqs[VHOST_NET_VQ_TX].vq;
1316         vqs[VHOST_NET_VQ_RX] = &n->vqs[VHOST_NET_VQ_RX].vq;
1317         n->vqs[VHOST_NET_VQ_TX].vq.handle_kick = handle_tx_kick;
1318         n->vqs[VHOST_NET_VQ_RX].vq.handle_kick = handle_rx_kick;
1319         for (i = 0; i < VHOST_NET_VQ_MAX; i++) {
1320                 n->vqs[i].ubufs = NULL;
1321                 n->vqs[i].ubuf_info = NULL;
1322                 n->vqs[i].upend_idx = 0;
1323                 n->vqs[i].done_idx = 0;
1324                 n->vqs[i].batched_xdp = 0;
1325                 n->vqs[i].vhost_hlen = 0;
1326                 n->vqs[i].sock_hlen = 0;
1327                 n->vqs[i].rx_ring = NULL;
1328                 vhost_net_buf_init(&n->vqs[i].rxq);
1329         }
1330         vhost_dev_init(dev, vqs, VHOST_NET_VQ_MAX,
1331                        UIO_MAXIOV + VHOST_NET_BATCH,
1332                        VHOST_NET_PKT_WEIGHT, VHOST_NET_WEIGHT, true,
1333                        NULL);
1334
1335         vhost_poll_init(n->poll + VHOST_NET_VQ_TX, handle_tx_net, EPOLLOUT, dev);
1336         vhost_poll_init(n->poll + VHOST_NET_VQ_RX, handle_rx_net, EPOLLIN, dev);
1337
1338         f->private_data = n;
1339         n->page_frag.page = NULL;
1340         n->refcnt_bias = 0;
1341
1342         return 0;
1343 }
1344
1345 static struct socket *vhost_net_stop_vq(struct vhost_net *n,
1346                                         struct vhost_virtqueue *vq)
1347 {
1348         struct socket *sock;
1349         struct vhost_net_virtqueue *nvq =
1350                 container_of(vq, struct vhost_net_virtqueue, vq);
1351
1352         mutex_lock(&vq->mutex);
1353         sock = vhost_vq_get_backend(vq);
1354         vhost_net_disable_vq(n, vq);
1355         vhost_vq_set_backend(vq, NULL);
1356         vhost_net_buf_unproduce(nvq);
1357         nvq->rx_ring = NULL;
1358         mutex_unlock(&vq->mutex);
1359         return sock;
1360 }
1361
1362 static void vhost_net_stop(struct vhost_net *n, struct socket **tx_sock,
1363                            struct socket **rx_sock)
1364 {
1365         *tx_sock = vhost_net_stop_vq(n, &n->vqs[VHOST_NET_VQ_TX].vq);
1366         *rx_sock = vhost_net_stop_vq(n, &n->vqs[VHOST_NET_VQ_RX].vq);
1367 }
1368
1369 static void vhost_net_flush_vq(struct vhost_net *n, int index)
1370 {
1371         vhost_poll_flush(n->poll + index);
1372         vhost_poll_flush(&n->vqs[index].vq.poll);
1373 }
1374
1375 static void vhost_net_flush(struct vhost_net *n)
1376 {
1377         vhost_net_flush_vq(n, VHOST_NET_VQ_TX);
1378         vhost_net_flush_vq(n, VHOST_NET_VQ_RX);
1379         if (n->vqs[VHOST_NET_VQ_TX].ubufs) {
1380                 mutex_lock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
1381                 n->tx_flush = true;
1382                 mutex_unlock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
1383                 /* Wait for all lower device DMAs done. */
1384                 vhost_net_ubuf_put_and_wait(n->vqs[VHOST_NET_VQ_TX].ubufs);
1385                 mutex_lock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
1386                 n->tx_flush = false;
1387                 atomic_set(&n->vqs[VHOST_NET_VQ_TX].ubufs->refcount, 1);
1388                 mutex_unlock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
1389         }
1390 }
1391
1392 static int vhost_net_release(struct inode *inode, struct file *f)
1393 {
1394         struct vhost_net *n = f->private_data;
1395         struct socket *tx_sock;
1396         struct socket *rx_sock;
1397
1398         vhost_net_stop(n, &tx_sock, &rx_sock);
1399         vhost_net_flush(n);
1400         vhost_dev_stop(&n->dev);
1401         vhost_dev_cleanup(&n->dev);
1402         vhost_net_vq_reset(n);
1403         if (tx_sock)
1404                 sockfd_put(tx_sock);
1405         if (rx_sock)
1406                 sockfd_put(rx_sock);
1407         /* Make sure no callbacks are outstanding */
1408         synchronize_rcu();
1409         /* We do an extra flush before freeing memory,
1410          * since jobs can re-queue themselves. */
1411         vhost_net_flush(n);
1412         kfree(n->vqs[VHOST_NET_VQ_RX].rxq.queue);
1413         kfree(n->vqs[VHOST_NET_VQ_TX].xdp);
1414         kfree(n->dev.vqs);
1415         if (n->page_frag.page)
1416                 __page_frag_cache_drain(n->page_frag.page, n->refcnt_bias);
1417         kvfree(n);
1418         return 0;
1419 }
1420
1421 static struct socket *get_raw_socket(int fd)
1422 {
1423         int r;
1424         struct socket *sock = sockfd_lookup(fd, &r);
1425
1426         if (!sock)
1427                 return ERR_PTR(-ENOTSOCK);
1428
1429         /* Parameter checking */
1430         if (sock->sk->sk_type != SOCK_RAW) {
1431                 r = -ESOCKTNOSUPPORT;
1432                 goto err;
1433         }
1434
1435         if (sock->sk->sk_family != AF_PACKET) {
1436                 r = -EPFNOSUPPORT;
1437                 goto err;
1438         }
1439         return sock;
1440 err:
1441         sockfd_put(sock);
1442         return ERR_PTR(r);
1443 }
1444
1445 static struct ptr_ring *get_tap_ptr_ring(int fd)
1446 {
1447         struct ptr_ring *ring;
1448         struct file *file = fget(fd);
1449
1450         if (!file)
1451                 return NULL;
1452         ring = tun_get_tx_ring(file);
1453         if (!IS_ERR(ring))
1454                 goto out;
1455         ring = tap_get_ptr_ring(file);
1456         if (!IS_ERR(ring))
1457                 goto out;
1458         ring = NULL;
1459 out:
1460         fput(file);
1461         return ring;
1462 }
1463
1464 static struct socket *get_tap_socket(int fd)
1465 {
1466         struct file *file = fget(fd);
1467         struct socket *sock;
1468
1469         if (!file)
1470                 return ERR_PTR(-EBADF);
1471         sock = tun_get_socket(file);
1472         if (!IS_ERR(sock))
1473                 return sock;
1474         sock = tap_get_socket(file);
1475         if (IS_ERR(sock))
1476                 fput(file);
1477         return sock;
1478 }
1479
1480 static struct socket *get_socket(int fd)
1481 {
1482         struct socket *sock;
1483
1484         /* special case to disable backend */
1485         if (fd == -1)
1486                 return NULL;
1487         sock = get_raw_socket(fd);
1488         if (!IS_ERR(sock))
1489                 return sock;
1490         sock = get_tap_socket(fd);
1491         if (!IS_ERR(sock))
1492                 return sock;
1493         return ERR_PTR(-ENOTSOCK);
1494 }
1495
1496 static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
1497 {
1498         struct socket *sock, *oldsock;
1499         struct vhost_virtqueue *vq;
1500         struct vhost_net_virtqueue *nvq;
1501         struct vhost_net_ubuf_ref *ubufs, *oldubufs = NULL;
1502         int r;
1503
1504         mutex_lock(&n->dev.mutex);
1505         r = vhost_dev_check_owner(&n->dev);
1506         if (r)
1507                 goto err;
1508
1509         if (index >= VHOST_NET_VQ_MAX) {
1510                 r = -ENOBUFS;
1511                 goto err;
1512         }
1513         vq = &n->vqs[index].vq;
1514         nvq = &n->vqs[index];
1515         mutex_lock(&vq->mutex);
1516
1517         /* Verify that ring has been setup correctly. */
1518         if (!vhost_vq_access_ok(vq)) {
1519                 r = -EFAULT;
1520                 goto err_vq;
1521         }
1522         sock = get_socket(fd);
1523         if (IS_ERR(sock)) {
1524                 r = PTR_ERR(sock);
1525                 goto err_vq;
1526         }
1527
1528         /* start polling new socket */
1529         oldsock = vhost_vq_get_backend(vq);
1530         if (sock != oldsock) {
1531                 ubufs = vhost_net_ubuf_alloc(vq,
1532                                              sock && vhost_sock_zcopy(sock));
1533                 if (IS_ERR(ubufs)) {
1534                         r = PTR_ERR(ubufs);
1535                         goto err_ubufs;
1536                 }
1537
1538                 vhost_net_disable_vq(n, vq);
1539                 vhost_vq_set_backend(vq, sock);
1540                 vhost_net_buf_unproduce(nvq);
1541                 r = vhost_vq_init_access(vq);
1542                 if (r)
1543                         goto err_used;
1544                 r = vhost_net_enable_vq(n, vq);
1545                 if (r)
1546                         goto err_used;
1547                 if (index == VHOST_NET_VQ_RX)
1548                         nvq->rx_ring = get_tap_ptr_ring(fd);
1549
1550                 oldubufs = nvq->ubufs;
1551                 nvq->ubufs = ubufs;
1552
1553                 n->tx_packets = 0;
1554                 n->tx_zcopy_err = 0;
1555                 n->tx_flush = false;
1556         }
1557
1558         mutex_unlock(&vq->mutex);
1559
1560         if (oldubufs) {
1561                 vhost_net_ubuf_put_wait_and_free(oldubufs);
1562                 mutex_lock(&vq->mutex);
1563                 vhost_zerocopy_signal_used(n, vq);
1564                 mutex_unlock(&vq->mutex);
1565         }
1566
1567         if (oldsock) {
1568                 vhost_net_flush_vq(n, index);
1569                 sockfd_put(oldsock);
1570         }
1571
1572         mutex_unlock(&n->dev.mutex);
1573         return 0;
1574
1575 err_used:
1576         vhost_vq_set_backend(vq, oldsock);
1577         vhost_net_enable_vq(n, vq);
1578         if (ubufs)
1579                 vhost_net_ubuf_put_wait_and_free(ubufs);
1580 err_ubufs:
1581         if (sock)
1582                 sockfd_put(sock);
1583 err_vq:
1584         mutex_unlock(&vq->mutex);
1585 err:
1586         mutex_unlock(&n->dev.mutex);
1587         return r;
1588 }
1589
1590 static long vhost_net_reset_owner(struct vhost_net *n)
1591 {
1592         struct socket *tx_sock = NULL;
1593         struct socket *rx_sock = NULL;
1594         long err;
1595         struct vhost_iotlb *umem;
1596
1597         mutex_lock(&n->dev.mutex);
1598         err = vhost_dev_check_owner(&n->dev);
1599         if (err)
1600                 goto done;
1601         umem = vhost_dev_reset_owner_prepare();
1602         if (!umem) {
1603                 err = -ENOMEM;
1604                 goto done;
1605         }
1606         vhost_net_stop(n, &tx_sock, &rx_sock);
1607         vhost_net_flush(n);
1608         vhost_dev_stop(&n->dev);
1609         vhost_dev_reset_owner(&n->dev, umem);
1610         vhost_net_vq_reset(n);
1611 done:
1612         mutex_unlock(&n->dev.mutex);
1613         if (tx_sock)
1614                 sockfd_put(tx_sock);
1615         if (rx_sock)
1616                 sockfd_put(rx_sock);
1617         return err;
1618 }
1619
1620 static int vhost_net_set_features(struct vhost_net *n, u64 features)
1621 {
1622         size_t vhost_hlen, sock_hlen, hdr_len;
1623         int i;
1624
1625         hdr_len = (features & ((1ULL << VIRTIO_NET_F_MRG_RXBUF) |
1626                                (1ULL << VIRTIO_F_VERSION_1))) ?
1627                         sizeof(struct virtio_net_hdr_mrg_rxbuf) :
1628                         sizeof(struct virtio_net_hdr);
1629         if (features & (1 << VHOST_NET_F_VIRTIO_NET_HDR)) {
1630                 /* vhost provides vnet_hdr */
1631                 vhost_hlen = hdr_len;
1632                 sock_hlen = 0;
1633         } else {
1634                 /* socket provides vnet_hdr */
1635                 vhost_hlen = 0;
1636                 sock_hlen = hdr_len;
1637         }
1638         mutex_lock(&n->dev.mutex);
1639         if ((features & (1 << VHOST_F_LOG_ALL)) &&
1640             !vhost_log_access_ok(&n->dev))
1641                 goto out_unlock;
1642
1643         if ((features & (1ULL << VIRTIO_F_ACCESS_PLATFORM))) {
1644                 if (vhost_init_device_iotlb(&n->dev, true))
1645                         goto out_unlock;
1646         }
1647
1648         for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
1649                 mutex_lock(&n->vqs[i].vq.mutex);
1650                 n->vqs[i].vq.acked_features = features;
1651                 n->vqs[i].vhost_hlen = vhost_hlen;
1652                 n->vqs[i].sock_hlen = sock_hlen;
1653                 mutex_unlock(&n->vqs[i].vq.mutex);
1654         }
1655         mutex_unlock(&n->dev.mutex);
1656         return 0;
1657
1658 out_unlock:
1659         mutex_unlock(&n->dev.mutex);
1660         return -EFAULT;
1661 }
1662
1663 static long vhost_net_set_owner(struct vhost_net *n)
1664 {
1665         int r;
1666
1667         mutex_lock(&n->dev.mutex);
1668         if (vhost_dev_has_owner(&n->dev)) {
1669                 r = -EBUSY;
1670                 goto out;
1671         }
1672         r = vhost_net_set_ubuf_info(n);
1673         if (r)
1674                 goto out;
1675         r = vhost_dev_set_owner(&n->dev);
1676         if (r)
1677                 vhost_net_clear_ubuf_info(n);
1678         vhost_net_flush(n);
1679 out:
1680         mutex_unlock(&n->dev.mutex);
1681         return r;
1682 }
1683
1684 static long vhost_net_ioctl(struct file *f, unsigned int ioctl,
1685                             unsigned long arg)
1686 {
1687         struct vhost_net *n = f->private_data;
1688         void __user *argp = (void __user *)arg;
1689         u64 __user *featurep = argp;
1690         struct vhost_vring_file backend;
1691         u64 features;
1692         int r;
1693
1694         switch (ioctl) {
1695         case VHOST_NET_SET_BACKEND:
1696                 if (copy_from_user(&backend, argp, sizeof backend))
1697                         return -EFAULT;
1698                 return vhost_net_set_backend(n, backend.index, backend.fd);
1699         case VHOST_GET_FEATURES:
1700                 features = VHOST_NET_FEATURES;
1701                 if (copy_to_user(featurep, &features, sizeof features))
1702                         return -EFAULT;
1703                 return 0;
1704         case VHOST_SET_FEATURES:
1705                 if (copy_from_user(&features, featurep, sizeof features))
1706                         return -EFAULT;
1707                 if (features & ~VHOST_NET_FEATURES)
1708                         return -EOPNOTSUPP;
1709                 return vhost_net_set_features(n, features);
1710         case VHOST_GET_BACKEND_FEATURES:
1711                 features = VHOST_NET_BACKEND_FEATURES;
1712                 if (copy_to_user(featurep, &features, sizeof(features)))
1713                         return -EFAULT;
1714                 return 0;
1715         case VHOST_SET_BACKEND_FEATURES:
1716                 if (copy_from_user(&features, featurep, sizeof(features)))
1717                         return -EFAULT;
1718                 if (features & ~VHOST_NET_BACKEND_FEATURES)
1719                         return -EOPNOTSUPP;
1720                 vhost_set_backend_features(&n->dev, features);
1721                 return 0;
1722         case VHOST_RESET_OWNER:
1723                 return vhost_net_reset_owner(n);
1724         case VHOST_SET_OWNER:
1725                 return vhost_net_set_owner(n);
1726         default:
1727                 mutex_lock(&n->dev.mutex);
1728                 r = vhost_dev_ioctl(&n->dev, ioctl, argp);
1729                 if (r == -ENOIOCTLCMD)
1730                         r = vhost_vring_ioctl(&n->dev, ioctl, argp);
1731                 else
1732                         vhost_net_flush(n);
1733                 mutex_unlock(&n->dev.mutex);
1734                 return r;
1735         }
1736 }
1737
1738 static ssize_t vhost_net_chr_read_iter(struct kiocb *iocb, struct iov_iter *to)
1739 {
1740         struct file *file = iocb->ki_filp;
1741         struct vhost_net *n = file->private_data;
1742         struct vhost_dev *dev = &n->dev;
1743         int noblock = file->f_flags & O_NONBLOCK;
1744
1745         return vhost_chr_read_iter(dev, to, noblock);
1746 }
1747
1748 static ssize_t vhost_net_chr_write_iter(struct kiocb *iocb,
1749                                         struct iov_iter *from)
1750 {
1751         struct file *file = iocb->ki_filp;
1752         struct vhost_net *n = file->private_data;
1753         struct vhost_dev *dev = &n->dev;
1754
1755         return vhost_chr_write_iter(dev, from);
1756 }
1757
1758 static __poll_t vhost_net_chr_poll(struct file *file, poll_table *wait)
1759 {
1760         struct vhost_net *n = file->private_data;
1761         struct vhost_dev *dev = &n->dev;
1762
1763         return vhost_chr_poll(file, dev, wait);
1764 }
1765
1766 static const struct file_operations vhost_net_fops = {
1767         .owner          = THIS_MODULE,
1768         .release        = vhost_net_release,
1769         .read_iter      = vhost_net_chr_read_iter,
1770         .write_iter     = vhost_net_chr_write_iter,
1771         .poll           = vhost_net_chr_poll,
1772         .unlocked_ioctl = vhost_net_ioctl,
1773         .compat_ioctl   = compat_ptr_ioctl,
1774         .open           = vhost_net_open,
1775         .llseek         = noop_llseek,
1776 };
1777
1778 static struct miscdevice vhost_net_misc = {
1779         .minor = VHOST_NET_MINOR,
1780         .name = "vhost-net",
1781         .fops = &vhost_net_fops,
1782 };
1783
1784 static int vhost_net_init(void)
1785 {
1786         if (experimental_zcopytx)
1787                 vhost_net_enable_zcopy(VHOST_NET_VQ_TX);
1788         return misc_register(&vhost_net_misc);
1789 }
1790 module_init(vhost_net_init);
1791
1792 static void vhost_net_exit(void)
1793 {
1794         misc_deregister(&vhost_net_misc);
1795 }
1796 module_exit(vhost_net_exit);
1797
1798 MODULE_VERSION("0.0.1");
1799 MODULE_LICENSE("GPL v2");
1800 MODULE_AUTHOR("Michael S. Tsirkin");
1801 MODULE_DESCRIPTION("Host kernel accelerator for virtio net");
1802 MODULE_ALIAS_MISCDEV(VHOST_NET_MINOR);
1803 MODULE_ALIAS("devname:vhost-net");