net/vmw_vsock/virtio_transport.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * virtio transport for vsock
   4  *
   5  * Copyright (C) 2013-2015 Red Hat, Inc.
   6  * Author: Asias He <asias@redhat.com>
   7  *         Stefan Hajnoczi <stefanha@redhat.com>
   8  *
   9  * Some of the code is take from Gerd Hoffmann <kraxel@redhat.com>'s
  10  * early virtio-vsock proof-of-concept bits.
  11  */
  12 #include <linux/spinlock.h>
  13 #include <linux/module.h>
  14 #include <linux/list.h>
  15 #include <linux/atomic.h>
  16 #include <linux/virtio.h>
  17 #include <linux/virtio_ids.h>
  18 #include <linux/virtio_config.h>
  19 #include <linux/virtio_vsock.h>
  20 #include <net/sock.h>
  21 #include <linux/mutex.h>
  22 #include <net/af_vsock.h>
  23
  24 static struct workqueue_struct *virtio_vsock_workqueue;
  25 static struct virtio_vsock __rcu *the_virtio_vsock;
  26 static DEFINE_MUTEX(the_virtio_vsock_mutex); /* protects the_virtio_vsock */
  27 static struct virtio_transport virtio_transport; /* forward declaration */
  28
  29 struct virtio_vsock {
  30         struct virtio_device *vdev;
  31         struct virtqueue *vqs[VSOCK_VQ_MAX];
  32
  33         /* Virtqueue processing is deferred to a workqueue */
  34         struct work_struct tx_work;
  35         struct work_struct rx_work;
  36         struct work_struct event_work;
  37
  38         /* The following fields are protected by tx_lock.  vqs[VSOCK_VQ_TX]
  39          * must be accessed with tx_lock held.
  40          */
  41         struct mutex tx_lock;
  42         bool tx_run;
  43
  44         struct work_struct send_pkt_work;
  45         struct sk_buff_head send_pkt_queue;
  46
  47         atomic_t queued_replies;
  48
  49         /* The following fields are protected by rx_lock.  vqs[VSOCK_VQ_RX]
  50          * must be accessed with rx_lock held.
  51          */
  52         struct mutex rx_lock;
  53         bool rx_run;
  54         int rx_buf_nr;
  55         int rx_buf_max_nr;
  56
  57         /* The following fields are protected by event_lock.
  58          * vqs[VSOCK_VQ_EVENT] must be accessed with event_lock held.
  59          */
  60         struct mutex event_lock;
  61         bool event_run;
  62         struct virtio_vsock_event event_list[8];
  63
  64         u32 guest_cid;
  65         bool seqpacket_allow;
  66
  67         /* These fields are used only in tx path in function
  68          * 'virtio_transport_send_pkt_work()', so to save
  69          * stack space in it, place both of them here. Each
  70          * pointer from 'out_sgs' points to the corresponding
  71          * element in 'out_bufs' - this is initialized in
  72          * 'virtio_vsock_probe()'. Both fields are protected
  73          * by 'tx_lock'. +1 is needed for packet header.
  74          */
  75         struct scatterlist *out_sgs[MAX_SKB_FRAGS + 1];
  76         struct scatterlist out_bufs[MAX_SKB_FRAGS + 1];
  77 };
  78
  79 static u32 virtio_transport_get_local_cid(void)
  80 {
  81         struct virtio_vsock *vsock;
  82         u32 ret;
  83
  84         rcu_read_lock();
  85         vsock = rcu_dereference(the_virtio_vsock);
  86         if (!vsock) {
  87                 ret = VMADDR_CID_ANY;
  88                 goto out_rcu;
  89         }
  90
  91         ret = vsock->guest_cid;
  92 out_rcu:
  93         rcu_read_unlock();
  94         return ret;
  95 }
  96
  97 /* Caller need to hold vsock->tx_lock on vq */
  98 static int virtio_transport_send_skb(struct sk_buff *skb, struct virtqueue *vq,
  99                                      struct virtio_vsock *vsock, gfp_t gfp)
 100 {
 101         int ret, in_sg = 0, out_sg = 0;
 102         struct scatterlist **sgs;
 103
 104         sgs = vsock->out_sgs;
 105         sg_init_one(sgs[out_sg], virtio_vsock_hdr(skb),
 106                     sizeof(*virtio_vsock_hdr(skb)));
 107         out_sg++;
 108
 109         if (!skb_is_nonlinear(skb)) {
 110                 if (skb->len > 0) {
 111                         sg_init_one(sgs[out_sg], skb->data, skb->len);
 112                         out_sg++;
 113                 }
 114         } else {
 115                 struct skb_shared_info *si;
 116                 int i;
 117
 118                 /* If skb is nonlinear, then its buffer must contain
 119                  * only header and nothing more. Data is stored in
 120                  * the fragged part.
 121                  */
 122                 WARN_ON_ONCE(skb_headroom(skb) != sizeof(*virtio_vsock_hdr(skb)));
 123
 124                 si = skb_shinfo(skb);
 125
 126                 for (i = 0; i < si->nr_frags; i++) {
 127                         skb_frag_t *skb_frag = &si->frags[i];
 128                         void *va;
 129
 130                         /* We will use 'page_to_virt()' for the userspace page
 131                          * here, because virtio or dma-mapping layers will call
 132                          * 'virt_to_phys()' later to fill the buffer descriptor.
 133                          * We don't touch memory at "virtual" address of this page.
 134                          */
 135                         va = page_to_virt(skb_frag_page(skb_frag));
 136                         sg_init_one(sgs[out_sg],
 137                                     va + skb_frag_off(skb_frag),
 138                                     skb_frag_size(skb_frag));
 139                         out_sg++;
 140                 }
 141         }
 142
 143         ret = virtqueue_add_sgs(vq, sgs, out_sg, in_sg, skb, gfp);
 144         /* Usually this means that there is no more space available in
 145          * the vq
 146          */
 147         if (ret < 0)
 148                 return ret;
 149
 150         virtio_transport_deliver_tap_pkt(skb);
 151         return 0;
 152 }
 153
 154 static void
 155 virtio_transport_send_pkt_work(struct work_struct *work)
 156 {
 157         struct virtio_vsock *vsock =
 158                 container_of(work, struct virtio_vsock, send_pkt_work);
 159         struct virtqueue *vq;
 160         bool added = false;
 161         bool restart_rx = false;
 162
 163         mutex_lock(&vsock->tx_lock);
 164
 165         if (!vsock->tx_run)
 166                 goto out;
 167
 168         vq = vsock->vqs[VSOCK_VQ_TX];
 169
 170         for (;;) {
 171                 struct sk_buff *skb;
 172                 bool reply;
 173                 int ret;
 174
 175                 skb = virtio_vsock_skb_dequeue(&vsock->send_pkt_queue);
 176                 if (!skb)
 177                         break;
 178
 179                 reply = virtio_vsock_skb_reply(skb);
 180
 181                 ret = virtio_transport_send_skb(skb, vq, vsock, GFP_KERNEL);
 182                 if (ret < 0) {
 183                         virtio_vsock_skb_queue_head(&vsock->send_pkt_queue, skb);
 184                         break;
 185                 }
 186
 187                 if (reply) {
 188                         struct virtqueue *rx_vq = vsock->vqs[VSOCK_VQ_RX];
 189                         int val;
 190
 191                         val = atomic_dec_return(&vsock->queued_replies);
 192
 193                         /* Do we now have resources to resume rx processing? */
 194                         if (val + 1 == virtqueue_get_vring_size(rx_vq))
 195                                 restart_rx = true;
 196                 }
 197
 198                 added = true;
 199         }
 200
 201         if (added)
 202                 virtqueue_kick(vq);
 203
 204 out:
 205         mutex_unlock(&vsock->tx_lock);
 206
 207         if (restart_rx)
 208                 queue_work(virtio_vsock_workqueue, &vsock->rx_work);
 209 }
 210
 211 /* Caller need to hold RCU for vsock.
 212  * Returns 0 if the packet is successfully put on the vq.
 213  */
 214 static int virtio_transport_send_skb_fast_path(struct virtio_vsock *vsock, struct sk_buff *skb)
 215 {
 216         struct virtqueue *vq = vsock->vqs[VSOCK_VQ_TX];
 217         int ret;
 218
 219         /* Inside RCU, can't sleep! */
 220         ret = mutex_trylock(&vsock->tx_lock);
 221         if (unlikely(ret == 0))
 222                 return -EBUSY;
 223
 224         ret = virtio_transport_send_skb(skb, vq, vsock, GFP_ATOMIC);
 225         if (ret == 0)
 226                 virtqueue_kick(vq);
 227
 228         mutex_unlock(&vsock->tx_lock);
 229
 230         return ret;
 231 }
 232
 233 static int
 234 virtio_transport_send_pkt(struct sk_buff *skb)
 235 {
 236         struct virtio_vsock_hdr *hdr;
 237         struct virtio_vsock *vsock;
 238         int len = skb->len;
 239
 240         hdr = virtio_vsock_hdr(skb);
 241
 242         rcu_read_lock();
 243         vsock = rcu_dereference(the_virtio_vsock);
 244         if (!vsock) {
 245                 kfree_skb(skb);
 246                 len = -ENODEV;
 247                 goto out_rcu;
 248         }
 249
 250         if (le64_to_cpu(hdr->dst_cid) == vsock->guest_cid) {
 251                 kfree_skb(skb);
 252                 len = -ENODEV;
 253                 goto out_rcu;
 254         }
 255
 256         /* If send_pkt_queue is empty, we can safely bypass this queue
 257          * because packet order is maintained and (try) to put the packet
 258          * on the virtqueue using virtio_transport_send_skb_fast_path.
 259          * If this fails we simply put the packet on the intermediate
 260          * queue and schedule the worker.
 261          */
 262         if (!skb_queue_empty_lockless(&vsock->send_pkt_queue) ||
 263             virtio_transport_send_skb_fast_path(vsock, skb)) {
 264                 if (virtio_vsock_skb_reply(skb))
 265                         atomic_inc(&vsock->queued_replies);
 266
 267                 virtio_vsock_skb_queue_tail(&vsock->send_pkt_queue, skb);
 268                 queue_work(virtio_vsock_workqueue, &vsock->send_pkt_work);
 269         }
 270
 271 out_rcu:
 272         rcu_read_unlock();
 273         return len;
 274 }
 275
 276 static int
 277 virtio_transport_cancel_pkt(struct vsock_sock *vsk)
 278 {
 279         struct virtio_vsock *vsock;
 280         int cnt = 0, ret;
 281
 282         rcu_read_lock();
 283         vsock = rcu_dereference(the_virtio_vsock);
 284         if (!vsock) {
 285                 ret = -ENODEV;
 286                 goto out_rcu;
 287         }
 288
 289         cnt = virtio_transport_purge_skbs(vsk, &vsock->send_pkt_queue);
 290
 291         if (cnt) {
 292                 struct virtqueue *rx_vq = vsock->vqs[VSOCK_VQ_RX];
 293                 int new_cnt;
 294
 295                 new_cnt = atomic_sub_return(cnt, &vsock->queued_replies);
 296                 if (new_cnt + cnt >= virtqueue_get_vring_size(rx_vq) &&
 297                     new_cnt < virtqueue_get_vring_size(rx_vq))
 298                         queue_work(virtio_vsock_workqueue, &vsock->rx_work);
 299         }
 300
 301         ret = 0;
 302
 303 out_rcu:
 304         rcu_read_unlock();
 305         return ret;
 306 }
 307
 308 static void virtio_vsock_rx_fill(struct virtio_vsock *vsock)
 309 {
 310         int total_len = VIRTIO_VSOCK_DEFAULT_RX_BUF_SIZE + VIRTIO_VSOCK_SKB_HEADROOM;
 311         struct scatterlist pkt, *p;
 312         struct virtqueue *vq;
 313         struct sk_buff *skb;
 314         int ret;
 315
 316         vq = vsock->vqs[VSOCK_VQ_RX];
 317
 318         do {
 319                 skb = virtio_vsock_alloc_skb(total_len, GFP_KERNEL);
 320                 if (!skb)
 321                         break;
 322
 323                 memset(skb->head, 0, VIRTIO_VSOCK_SKB_HEADROOM);
 324                 sg_init_one(&pkt, virtio_vsock_hdr(skb), total_len);
 325                 p = &pkt;
 326                 ret = virtqueue_add_sgs(vq, &p, 0, 1, skb, GFP_KERNEL);
 327                 if (ret < 0) {
 328                         kfree_skb(skb);
 329                         break;
 330                 }
 331
 332                 vsock->rx_buf_nr++;
 333         } while (vq->num_free);
 334         if (vsock->rx_buf_nr > vsock->rx_buf_max_nr)
 335                 vsock->rx_buf_max_nr = vsock->rx_buf_nr;
 336         virtqueue_kick(vq);
 337 }
 338
 339 static void virtio_transport_tx_work(struct work_struct *work)
 340 {
 341         struct virtio_vsock *vsock =
 342                 container_of(work, struct virtio_vsock, tx_work);
 343         struct virtqueue *vq;
 344         bool added = false;
 345
 346         vq = vsock->vqs[VSOCK_VQ_TX];
 347         mutex_lock(&vsock->tx_lock);
 348
 349         if (!vsock->tx_run)
 350                 goto out;
 351
 352         do {
 353                 struct sk_buff *skb;
 354                 unsigned int len;
 355
 356                 virtqueue_disable_cb(vq);
 357                 while ((skb = virtqueue_get_buf(vq, &len)) != NULL) {
 358                         virtio_transport_consume_skb_sent(skb, true);
 359                         added = true;
 360                 }
 361         } while (!virtqueue_enable_cb(vq));
 362
 363 out:
 364         mutex_unlock(&vsock->tx_lock);
 365
 366         if (added)
 367                 queue_work(virtio_vsock_workqueue, &vsock->send_pkt_work);
 368 }
 369
 370 /* Is there space left for replies to rx packets? */
 371 static bool virtio_transport_more_replies(struct virtio_vsock *vsock)
 372 {
 373         struct virtqueue *vq = vsock->vqs[VSOCK_VQ_RX];
 374         int val;
 375
 376         smp_rmb(); /* paired with atomic_inc() and atomic_dec_return() */
 377         val = atomic_read(&vsock->queued_replies);
 378
 379         return val < virtqueue_get_vring_size(vq);
 380 }
 381
 382 /* event_lock must be held */
 383 static int virtio_vsock_event_fill_one(struct virtio_vsock *vsock,
 384                                        struct virtio_vsock_event *event)
 385 {
 386         struct scatterlist sg;
 387         struct virtqueue *vq;
 388
 389         vq = vsock->vqs[VSOCK_VQ_EVENT];
 390
 391         sg_init_one(&sg, event, sizeof(*event));
 392
 393         return virtqueue_add_inbuf(vq, &sg, 1, event, GFP_KERNEL);
 394 }
 395
 396 /* event_lock must be held */
 397 static void virtio_vsock_event_fill(struct virtio_vsock *vsock)
 398 {
 399         size_t i;
 400
 401         for (i = 0; i < ARRAY_SIZE(vsock->event_list); i++) {
 402                 struct virtio_vsock_event *event = &vsock->event_list[i];
 403
 404                 virtio_vsock_event_fill_one(vsock, event);
 405         }
 406
 407         virtqueue_kick(vsock->vqs[VSOCK_VQ_EVENT]);
 408 }
 409
 410 static void virtio_vsock_reset_sock(struct sock *sk)
 411 {
 412         /* vmci_transport.c doesn't take sk_lock here either.  At least we're
 413          * under vsock_table_lock so the sock cannot disappear while we're
 414          * executing.
 415          */
 416
 417         sk->sk_state = TCP_CLOSE;
 418         sk->sk_err = ECONNRESET;
 419         sk_error_report(sk);
 420 }
 421
 422 static void virtio_vsock_update_guest_cid(struct virtio_vsock *vsock)
 423 {
 424         struct virtio_device *vdev = vsock->vdev;
 425         __le64 guest_cid;
 426
 427         vdev->config->get(vdev, offsetof(struct virtio_vsock_config, guest_cid),
 428                           &guest_cid, sizeof(guest_cid));
 429         vsock->guest_cid = le64_to_cpu(guest_cid);
 430 }
 431
 432 /* event_lock must be held */
 433 static void virtio_vsock_event_handle(struct virtio_vsock *vsock,
 434                                       struct virtio_vsock_event *event)
 435 {
 436         switch (le32_to_cpu(event->id)) {
 437         case VIRTIO_VSOCK_EVENT_TRANSPORT_RESET:
 438                 virtio_vsock_update_guest_cid(vsock);
 439                 vsock_for_each_connected_socket(&virtio_transport.transport,
 440                                                 virtio_vsock_reset_sock);
 441                 break;
 442         }
 443 }
 444
 445 static void virtio_transport_event_work(struct work_struct *work)
 446 {
 447         struct virtio_vsock *vsock =
 448                 container_of(work, struct virtio_vsock, event_work);
 449         struct virtqueue *vq;
 450
 451         vq = vsock->vqs[VSOCK_VQ_EVENT];
 452
 453         mutex_lock(&vsock->event_lock);
 454
 455         if (!vsock->event_run)
 456                 goto out;
 457
 458         do {
 459                 struct virtio_vsock_event *event;
 460                 unsigned int len;
 461
 462                 virtqueue_disable_cb(vq);
 463                 while ((event = virtqueue_get_buf(vq, &len)) != NULL) {
 464                         if (len == sizeof(*event))
 465                                 virtio_vsock_event_handle(vsock, event);
 466
 467                         virtio_vsock_event_fill_one(vsock, event);
 468                 }
 469         } while (!virtqueue_enable_cb(vq));
 470
 471         virtqueue_kick(vsock->vqs[VSOCK_VQ_EVENT]);
 472 out:
 473         mutex_unlock(&vsock->event_lock);
 474 }
 475
 476 static void virtio_vsock_event_done(struct virtqueue *vq)
 477 {
 478         struct virtio_vsock *vsock = vq->vdev->priv;
 479
 480         if (!vsock)
 481                 return;
 482         queue_work(virtio_vsock_workqueue, &vsock->event_work);
 483 }
 484
 485 static void virtio_vsock_tx_done(struct virtqueue *vq)
 486 {
 487         struct virtio_vsock *vsock = vq->vdev->priv;
 488
 489         if (!vsock)
 490                 return;
 491         queue_work(virtio_vsock_workqueue, &vsock->tx_work);
 492 }
 493
 494 static void virtio_vsock_rx_done(struct virtqueue *vq)
 495 {
 496         struct virtio_vsock *vsock = vq->vdev->priv;
 497
 498         if (!vsock)
 499                 return;
 500         queue_work(virtio_vsock_workqueue, &vsock->rx_work);
 501 }
 502
 503 static bool virtio_transport_can_msgzerocopy(int bufs_num)
 504 {
 505         struct virtio_vsock *vsock;
 506         bool res = false;
 507
 508         rcu_read_lock();
 509
 510         vsock = rcu_dereference(the_virtio_vsock);
 511         if (vsock) {
 512                 struct virtqueue *vq = vsock->vqs[VSOCK_VQ_TX];
 513
 514                 /* Check that tx queue is large enough to keep whole
 515                  * data to send. This is needed, because when there is
 516                  * not enough free space in the queue, current skb to
 517                  * send will be reinserted to the head of tx list of
 518                  * the socket to retry transmission later, so if skb
 519                  * is bigger than whole queue, it will be reinserted
 520                  * again and again, thus blocking other skbs to be sent.
 521                  * Each page of the user provided buffer will be added
 522                  * as a single buffer to the tx virtqueue, so compare
 523                  * number of pages against maximum capacity of the queue.
 524                  */
 525                 if (bufs_num <= vq->num_max)
 526                         res = true;
 527         }
 528
 529         rcu_read_unlock();
 530
 531         return res;
 532 }
 533
 534 static bool virtio_transport_msgzerocopy_allow(void)
 535 {
 536         return true;
 537 }
 538
 539 static bool virtio_transport_seqpacket_allow(u32 remote_cid);
 540
 541 static struct virtio_transport virtio_transport = {
 542         .transport = {
 543                 .module                   = THIS_MODULE,
 544
 545                 .get_local_cid            = virtio_transport_get_local_cid,
 546
 547                 .init                     = virtio_transport_do_socket_init,
 548                 .destruct                 = virtio_transport_destruct,
 549                 .release                  = virtio_transport_release,
 550                 .connect                  = virtio_transport_connect,
 551                 .shutdown                 = virtio_transport_shutdown,
 552                 .cancel_pkt               = virtio_transport_cancel_pkt,
 553
 554                 .dgram_bind               = virtio_transport_dgram_bind,
 555                 .dgram_dequeue            = virtio_transport_dgram_dequeue,
 556                 .dgram_enqueue            = virtio_transport_dgram_enqueue,
 557                 .dgram_allow              = virtio_transport_dgram_allow,
 558
 559                 .stream_dequeue           = virtio_transport_stream_dequeue,
 560                 .stream_enqueue           = virtio_transport_stream_enqueue,
 561                 .stream_has_data          = virtio_transport_stream_has_data,
 562                 .stream_has_space         = virtio_transport_stream_has_space,
 563                 .stream_rcvhiwat          = virtio_transport_stream_rcvhiwat,
 564                 .stream_is_active         = virtio_transport_stream_is_active,
 565                 .stream_allow             = virtio_transport_stream_allow,
 566
 567                 .seqpacket_dequeue        = virtio_transport_seqpacket_dequeue,
 568                 .seqpacket_enqueue        = virtio_transport_seqpacket_enqueue,
 569                 .seqpacket_allow          = virtio_transport_seqpacket_allow,
 570                 .seqpacket_has_data       = virtio_transport_seqpacket_has_data,
 571
 572                 .msgzerocopy_allow        = virtio_transport_msgzerocopy_allow,
 573
 574                 .notify_poll_in           = virtio_transport_notify_poll_in,
 575                 .notify_poll_out          = virtio_transport_notify_poll_out,
 576                 .notify_recv_init         = virtio_transport_notify_recv_init,
 577                 .notify_recv_pre_block    = virtio_transport_notify_recv_pre_block,
 578                 .notify_recv_pre_dequeue  = virtio_transport_notify_recv_pre_dequeue,
 579                 .notify_recv_post_dequeue = virtio_transport_notify_recv_post_dequeue,
 580                 .notify_send_init         = virtio_transport_notify_send_init,
 581                 .notify_send_pre_block    = virtio_transport_notify_send_pre_block,
 582                 .notify_send_pre_enqueue  = virtio_transport_notify_send_pre_enqueue,
 583                 .notify_send_post_enqueue = virtio_transport_notify_send_post_enqueue,
 584                 .notify_buffer_size       = virtio_transport_notify_buffer_size,
 585                 .notify_set_rcvlowat      = virtio_transport_notify_set_rcvlowat,
 586
 587                 .unsent_bytes             = virtio_transport_unsent_bytes,
 588
 589                 .read_skb = virtio_transport_read_skb,
 590         },
 591
 592         .send_pkt = virtio_transport_send_pkt,
 593         .can_msgzerocopy = virtio_transport_can_msgzerocopy,
 594 };
 595
 596 static bool virtio_transport_seqpacket_allow(u32 remote_cid)
 597 {
 598         struct virtio_vsock *vsock;
 599         bool seqpacket_allow;
 600
 601         seqpacket_allow = false;
 602         rcu_read_lock();
 603         vsock = rcu_dereference(the_virtio_vsock);
 604         if (vsock)
 605                 seqpacket_allow = vsock->seqpacket_allow;
 606         rcu_read_unlock();
 607
 608         return seqpacket_allow;
 609 }
 610
 611 static void virtio_transport_rx_work(struct work_struct *work)
 612 {
 613         struct virtio_vsock *vsock =
 614                 container_of(work, struct virtio_vsock, rx_work);
 615         struct virtqueue *vq;
 616
 617         vq = vsock->vqs[VSOCK_VQ_RX];
 618
 619         mutex_lock(&vsock->rx_lock);
 620
 621         if (!vsock->rx_run)
 622                 goto out;
 623
 624         do {
 625                 virtqueue_disable_cb(vq);
 626                 for (;;) {
 627                         struct sk_buff *skb;
 628                         unsigned int len;
 629
 630                         if (!virtio_transport_more_replies(vsock)) {
 631                                 /* Stop rx until the device processes already
 632                                  * pending replies.  Leave rx virtqueue
 633                                  * callbacks disabled.
 634                                  */
 635                                 goto out;
 636                         }
 637
 638                         skb = virtqueue_get_buf(vq, &len);
 639                         if (!skb)
 640                                 break;
 641
 642                         vsock->rx_buf_nr--;
 643
 644                         /* Drop short/long packets */
 645                         if (unlikely(len < sizeof(struct virtio_vsock_hdr) ||
 646                                      len > virtio_vsock_skb_len(skb))) {
 647                                 kfree_skb(skb);
 648                                 continue;
 649                         }
 650
 651                         virtio_vsock_skb_rx_put(skb);
 652                         virtio_transport_deliver_tap_pkt(skb);
 653                         virtio_transport_recv_pkt(&virtio_transport, skb);
 654                 }
 655         } while (!virtqueue_enable_cb(vq));
 656
 657 out:
 658         if (vsock->rx_buf_nr < vsock->rx_buf_max_nr / 2)
 659                 virtio_vsock_rx_fill(vsock);
 660         mutex_unlock(&vsock->rx_lock);
 661 }
 662
 663 static int virtio_vsock_vqs_init(struct virtio_vsock *vsock)
 664 {
 665         struct virtio_device *vdev = vsock->vdev;
 666         struct virtqueue_info vqs_info[] = {
 667                 { "rx", virtio_vsock_rx_done },
 668                 { "tx", virtio_vsock_tx_done },
 669                 { "event", virtio_vsock_event_done },
 670         };
 671         int ret;
 672
 673         ret = virtio_find_vqs(vdev, VSOCK_VQ_MAX, vsock->vqs, vqs_info, NULL);
 674         if (ret < 0)
 675                 return ret;
 676
 677         virtio_vsock_update_guest_cid(vsock);
 678
 679         virtio_device_ready(vdev);
 680
 681         return 0;
 682 }
 683
 684 static void virtio_vsock_vqs_start(struct virtio_vsock *vsock)
 685 {
 686         mutex_lock(&vsock->tx_lock);
 687         vsock->tx_run = true;
 688         mutex_unlock(&vsock->tx_lock);
 689
 690         mutex_lock(&vsock->rx_lock);
 691         virtio_vsock_rx_fill(vsock);
 692         vsock->rx_run = true;
 693         mutex_unlock(&vsock->rx_lock);
 694
 695         mutex_lock(&vsock->event_lock);
 696         virtio_vsock_event_fill(vsock);
 697         vsock->event_run = true;
 698         mutex_unlock(&vsock->event_lock);
 699
 700         /* virtio_transport_send_pkt() can queue packets once
 701          * the_virtio_vsock is set, but they won't be processed until
 702          * vsock->tx_run is set to true. We queue vsock->send_pkt_work
 703          * when initialization finishes to send those packets queued
 704          * earlier.
 705          * We don't need to queue the other workers (rx, event) because
 706          * as long as we don't fill the queues with empty buffers, the
 707          * host can't send us any notification.
 708          */
 709         queue_work(virtio_vsock_workqueue, &vsock->send_pkt_work);
 710 }
 711
 712 static void virtio_vsock_vqs_del(struct virtio_vsock *vsock)
 713 {
 714         struct virtio_device *vdev = vsock->vdev;
 715         struct sk_buff *skb;
 716
 717         /* Reset all connected sockets when the VQs disappear */
 718         vsock_for_each_connected_socket(&virtio_transport.transport,
 719                                         virtio_vsock_reset_sock);
 720
 721         /* Stop all work handlers to make sure no one is accessing the device,
 722          * so we can safely call virtio_reset_device().
 723          */
 724         mutex_lock(&vsock->rx_lock);
 725         vsock->rx_run = false;
 726         mutex_unlock(&vsock->rx_lock);
 727
 728         mutex_lock(&vsock->tx_lock);
 729         vsock->tx_run = false;
 730         mutex_unlock(&vsock->tx_lock);
 731
 732         mutex_lock(&vsock->event_lock);
 733         vsock->event_run = false;
 734         mutex_unlock(&vsock->event_lock);
 735
 736         /* Flush all device writes and interrupts, device will not use any
 737          * more buffers.
 738          */
 739         virtio_reset_device(vdev);
 740
 741         mutex_lock(&vsock->rx_lock);
 742         while ((skb = virtqueue_detach_unused_buf(vsock->vqs[VSOCK_VQ_RX])))
 743                 kfree_skb(skb);
 744         mutex_unlock(&vsock->rx_lock);
 745
 746         mutex_lock(&vsock->tx_lock);
 747         while ((skb = virtqueue_detach_unused_buf(vsock->vqs[VSOCK_VQ_TX])))
 748                 kfree_skb(skb);
 749         mutex_unlock(&vsock->tx_lock);
 750
 751         virtio_vsock_skb_queue_purge(&vsock->send_pkt_queue);
 752
 753         /* Delete virtqueues and flush outstanding callbacks if any */
 754         vdev->config->del_vqs(vdev);
 755 }
 756
 757 static int virtio_vsock_probe(struct virtio_device *vdev)
 758 {
 759         struct virtio_vsock *vsock = NULL;
 760         int ret;
 761         int i;
 762
 763         ret = mutex_lock_interruptible(&the_virtio_vsock_mutex);
 764         if (ret)
 765                 return ret;
 766
 767         /* Only one virtio-vsock device per guest is supported */
 768         if (rcu_dereference_protected(the_virtio_vsock,
 769                                 lockdep_is_held(&the_virtio_vsock_mutex))) {
 770                 ret = -EBUSY;
 771                 goto out;
 772         }
 773
 774         vsock = kzalloc(sizeof(*vsock), GFP_KERNEL);
 775         if (!vsock) {
 776                 ret = -ENOMEM;
 777                 goto out;
 778         }
 779
 780         vsock->vdev = vdev;
 781
 782         vsock->rx_buf_nr = 0;
 783         vsock->rx_buf_max_nr = 0;
 784         atomic_set(&vsock->queued_replies, 0);
 785
 786         mutex_init(&vsock->tx_lock);
 787         mutex_init(&vsock->rx_lock);
 788         mutex_init(&vsock->event_lock);
 789         skb_queue_head_init(&vsock->send_pkt_queue);
 790         INIT_WORK(&vsock->rx_work, virtio_transport_rx_work);
 791         INIT_WORK(&vsock->tx_work, virtio_transport_tx_work);
 792         INIT_WORK(&vsock->event_work, virtio_transport_event_work);
 793         INIT_WORK(&vsock->send_pkt_work, virtio_transport_send_pkt_work);
 794
 795         if (virtio_has_feature(vdev, VIRTIO_VSOCK_F_SEQPACKET))
 796                 vsock->seqpacket_allow = true;
 797
 798         vdev->priv = vsock;
 799
 800         ret = virtio_vsock_vqs_init(vsock);
 801         if (ret < 0)
 802                 goto out;
 803
 804         for (i = 0; i < ARRAY_SIZE(vsock->out_sgs); i++)
 805                 vsock->out_sgs[i] = &vsock->out_bufs[i];
 806
 807         rcu_assign_pointer(the_virtio_vsock, vsock);
 808         virtio_vsock_vqs_start(vsock);
 809
 810         mutex_unlock(&the_virtio_vsock_mutex);
 811
 812         return 0;
 813
 814 out:
 815         kfree(vsock);
 816         mutex_unlock(&the_virtio_vsock_mutex);
 817         return ret;
 818 }
 819
 820 static void virtio_vsock_remove(struct virtio_device *vdev)
 821 {
 822         struct virtio_vsock *vsock = vdev->priv;
 823
 824         mutex_lock(&the_virtio_vsock_mutex);
 825
 826         vdev->priv = NULL;
 827         rcu_assign_pointer(the_virtio_vsock, NULL);
 828         synchronize_rcu();
 829
 830         virtio_vsock_vqs_del(vsock);
 831
 832         /* Other works can be queued before 'config->del_vqs()', so we flush
 833          * all works before to free the vsock object to avoid use after free.
 834          */
 835         flush_work(&vsock->rx_work);
 836         flush_work(&vsock->tx_work);
 837         flush_work(&vsock->event_work);
 838         flush_work(&vsock->send_pkt_work);
 839
 840         mutex_unlock(&the_virtio_vsock_mutex);
 841
 842         kfree(vsock);
 843 }
 844
 845 #ifdef CONFIG_PM_SLEEP
 846 static int virtio_vsock_freeze(struct virtio_device *vdev)
 847 {
 848         struct virtio_vsock *vsock = vdev->priv;
 849
 850         mutex_lock(&the_virtio_vsock_mutex);
 851
 852         rcu_assign_pointer(the_virtio_vsock, NULL);
 853         synchronize_rcu();
 854
 855         virtio_vsock_vqs_del(vsock);
 856
 857         mutex_unlock(&the_virtio_vsock_mutex);
 858
 859         return 0;
 860 }
 861
 862 static int virtio_vsock_restore(struct virtio_device *vdev)
 863 {
 864         struct virtio_vsock *vsock = vdev->priv;
 865         int ret;
 866
 867         mutex_lock(&the_virtio_vsock_mutex);
 868
 869         /* Only one virtio-vsock device per guest is supported */
 870         if (rcu_dereference_protected(the_virtio_vsock,
 871                                 lockdep_is_held(&the_virtio_vsock_mutex))) {
 872                 ret = -EBUSY;
 873                 goto out;
 874         }
 875
 876         ret = virtio_vsock_vqs_init(vsock);
 877         if (ret < 0)
 878                 goto out;
 879
 880         rcu_assign_pointer(the_virtio_vsock, vsock);
 881         virtio_vsock_vqs_start(vsock);
 882
 883 out:
 884         mutex_unlock(&the_virtio_vsock_mutex);
 885         return ret;
 886 }
 887 #endif /* CONFIG_PM_SLEEP */
 888
 889 static struct virtio_device_id id_table[] = {
 890         { VIRTIO_ID_VSOCK, VIRTIO_DEV_ANY_ID },
 891         { 0 },
 892 };
 893
 894 static unsigned int features[] = {
 895         VIRTIO_VSOCK_F_SEQPACKET
 896 };
 897
 898 static struct virtio_driver virtio_vsock_driver = {
 899         .feature_table = features,
 900         .feature_table_size = ARRAY_SIZE(features),
 901         .driver.name = KBUILD_MODNAME,
 902         .id_table = id_table,
 903         .probe = virtio_vsock_probe,
 904         .remove = virtio_vsock_remove,
 905 #ifdef CONFIG_PM_SLEEP
 906         .freeze = virtio_vsock_freeze,
 907         .restore = virtio_vsock_restore,
 908 #endif
 909 };
 910
 911 static int __init virtio_vsock_init(void)
 912 {
 913         int ret;
 914
 915         virtio_vsock_workqueue = alloc_workqueue("virtio_vsock", 0, 0);
 916         if (!virtio_vsock_workqueue)
 917                 return -ENOMEM;
 918
 919         ret = vsock_core_register(&virtio_transport.transport,
 920                                   VSOCK_TRANSPORT_F_G2H);
 921         if (ret)
 922                 goto out_wq;
 923
 924         ret = register_virtio_driver(&virtio_vsock_driver);
 925         if (ret)
 926                 goto out_vci;
 927
 928         return 0;
 929
 930 out_vci:
 931         vsock_core_unregister(&virtio_transport.transport);
 932 out_wq:
 933         destroy_workqueue(virtio_vsock_workqueue);
 934         return ret;
 935 }
 936
 937 static void __exit virtio_vsock_exit(void)
 938 {
 939         unregister_virtio_driver(&virtio_vsock_driver);
 940         vsock_core_unregister(&virtio_transport.transport);
 941         destroy_workqueue(virtio_vsock_workqueue);
 942 }
 943
 944 module_init(virtio_vsock_init);
 945 module_exit(virtio_vsock_exit);
 946 MODULE_LICENSE("GPL v2");
 947 MODULE_AUTHOR("Asias He");
 948 MODULE_DESCRIPTION("virtio transport for vsock");
 949 MODULE_DEVICE_TABLE(virtio, id_table);