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