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         spinlock_t send_pkt_list_lock;
  46         struct list_head send_pkt_list;
  47
  48         atomic_t queued_replies;
  49
  50         /* The following fields are protected by rx_lock.  vqs[VSOCK_VQ_RX]
  51          * must be accessed with rx_lock held.
  52          */
  53         struct mutex rx_lock;
  54         bool rx_run;
  55         int rx_buf_nr;
  56         int rx_buf_max_nr;
  57
  58         /* The following fields are protected by event_lock.
  59          * vqs[VSOCK_VQ_EVENT] must be accessed with event_lock held.
  60          */
  61         struct mutex event_lock;
  62         bool event_run;
  63         struct virtio_vsock_event event_list[8];
  64
  65         u32 guest_cid;
  66         bool seqpacket_allow;
  67 };
  68
  69 static u32 virtio_transport_get_local_cid(void)
  70 {
  71         struct virtio_vsock *vsock;
  72         u32 ret;
  73
  74         rcu_read_lock();
  75         vsock = rcu_dereference(the_virtio_vsock);
  76         if (!vsock) {
  77                 ret = VMADDR_CID_ANY;
  78                 goto out_rcu;
  79         }
  80
  81         ret = vsock->guest_cid;
  82 out_rcu:
  83         rcu_read_unlock();
  84         return ret;
  85 }
  86
  87 static void
  88 virtio_transport_send_pkt_work(struct work_struct *work)
  89 {
  90         struct virtio_vsock *vsock =
  91                 container_of(work, struct virtio_vsock, send_pkt_work);
  92         struct virtqueue *vq;
  93         bool added = false;
  94         bool restart_rx = false;
  95
  96         mutex_lock(&vsock->tx_lock);
  97
  98         if (!vsock->tx_run)
  99                 goto out;
 100
 101         vq = vsock->vqs[VSOCK_VQ_TX];
 102
 103         for (;;) {
 104                 struct virtio_vsock_pkt *pkt;
 105                 struct scatterlist hdr, buf, *sgs[2];
 106                 int ret, in_sg = 0, out_sg = 0;
 107                 bool reply;
 108
 109                 spin_lock_bh(&vsock->send_pkt_list_lock);
 110                 if (list_empty(&vsock->send_pkt_list)) {
 111                         spin_unlock_bh(&vsock->send_pkt_list_lock);
 112                         break;
 113                 }
 114
 115                 pkt = list_first_entry(&vsock->send_pkt_list,
 116                                        struct virtio_vsock_pkt, list);
 117                 list_del_init(&pkt->list);
 118                 spin_unlock_bh(&vsock->send_pkt_list_lock);
 119
 120                 virtio_transport_deliver_tap_pkt(pkt);
 121
 122                 reply = pkt->reply;
 123
 124                 sg_init_one(&hdr, &pkt->hdr, sizeof(pkt->hdr));
 125                 sgs[out_sg++] = &hdr;
 126                 if (pkt->buf) {
 127                         sg_init_one(&buf, pkt->buf, pkt->len);
 128                         sgs[out_sg++] = &buf;
 129                 }
 130
 131                 ret = virtqueue_add_sgs(vq, sgs, out_sg, in_sg, pkt, GFP_KERNEL);
 132                 /* Usually this means that there is no more space available in
 133                  * the vq
 134                  */
 135                 if (ret < 0) {
 136                         spin_lock_bh(&vsock->send_pkt_list_lock);
 137                         list_add(&pkt->list, &vsock->send_pkt_list);
 138                         spin_unlock_bh(&vsock->send_pkt_list_lock);
 139                         break;
 140                 }
 141
 142                 if (reply) {
 143                         struct virtqueue *rx_vq = vsock->vqs[VSOCK_VQ_RX];
 144                         int val;
 145
 146                         val = atomic_dec_return(&vsock->queued_replies);
 147
 148                         /* Do we now have resources to resume rx processing? */
 149                         if (val + 1 == virtqueue_get_vring_size(rx_vq))
 150                                 restart_rx = true;
 151                 }
 152
 153                 added = true;
 154         }
 155
 156         if (added)
 157                 virtqueue_kick(vq);
 158
 159 out:
 160         mutex_unlock(&vsock->tx_lock);
 161
 162         if (restart_rx)
 163                 queue_work(virtio_vsock_workqueue, &vsock->rx_work);
 164 }
 165
 166 static int
 167 virtio_transport_send_pkt(struct virtio_vsock_pkt *pkt)
 168 {
 169         struct virtio_vsock *vsock;
 170         int len = pkt->len;
 171
 172         rcu_read_lock();
 173         vsock = rcu_dereference(the_virtio_vsock);
 174         if (!vsock) {
 175                 virtio_transport_free_pkt(pkt);
 176                 len = -ENODEV;
 177                 goto out_rcu;
 178         }
 179
 180         if (le64_to_cpu(pkt->hdr.dst_cid) == vsock->guest_cid) {
 181                 virtio_transport_free_pkt(pkt);
 182                 len = -ENODEV;
 183                 goto out_rcu;
 184         }
 185
 186         if (pkt->reply)
 187                 atomic_inc(&vsock->queued_replies);
 188
 189         spin_lock_bh(&vsock->send_pkt_list_lock);
 190         list_add_tail(&pkt->list, &vsock->send_pkt_list);
 191         spin_unlock_bh(&vsock->send_pkt_list_lock);
 192
 193         queue_work(virtio_vsock_workqueue, &vsock->send_pkt_work);
 194
 195 out_rcu:
 196         rcu_read_unlock();
 197         return len;
 198 }
 199
 200 static int
 201 virtio_transport_cancel_pkt(struct vsock_sock *vsk)
 202 {
 203         struct virtio_vsock *vsock;
 204         struct virtio_vsock_pkt *pkt, *n;
 205         int cnt = 0, ret;
 206         LIST_HEAD(freeme);
 207
 208         rcu_read_lock();
 209         vsock = rcu_dereference(the_virtio_vsock);
 210         if (!vsock) {
 211                 ret = -ENODEV;
 212                 goto out_rcu;
 213         }
 214
 215         spin_lock_bh(&vsock->send_pkt_list_lock);
 216         list_for_each_entry_safe(pkt, n, &vsock->send_pkt_list, list) {
 217                 if (pkt->vsk != vsk)
 218                         continue;
 219                 list_move(&pkt->list, &freeme);
 220         }
 221         spin_unlock_bh(&vsock->send_pkt_list_lock);
 222
 223         list_for_each_entry_safe(pkt, n, &freeme, list) {
 224                 if (pkt->reply)
 225                         cnt++;
 226                 list_del(&pkt->list);
 227                 virtio_transport_free_pkt(pkt);
 228         }
 229
 230         if (cnt) {
 231                 struct virtqueue *rx_vq = vsock->vqs[VSOCK_VQ_RX];
 232                 int new_cnt;
 233
 234                 new_cnt = atomic_sub_return(cnt, &vsock->queued_replies);
 235                 if (new_cnt + cnt >= virtqueue_get_vring_size(rx_vq) &&
 236                     new_cnt < virtqueue_get_vring_size(rx_vq))
 237                         queue_work(virtio_vsock_workqueue, &vsock->rx_work);
 238         }
 239
 240         ret = 0;
 241
 242 out_rcu:
 243         rcu_read_unlock();
 244         return ret;
 245 }
 246
 247 static void virtio_vsock_rx_fill(struct virtio_vsock *vsock)
 248 {
 249         int buf_len = VIRTIO_VSOCK_DEFAULT_RX_BUF_SIZE;
 250         struct virtio_vsock_pkt *pkt;
 251         struct scatterlist hdr, buf, *sgs[2];
 252         struct virtqueue *vq;
 253         int ret;
 254
 255         vq = vsock->vqs[VSOCK_VQ_RX];
 256
 257         do {
 258                 pkt = kzalloc(sizeof(*pkt), GFP_KERNEL);
 259                 if (!pkt)
 260                         break;
 261
 262                 pkt->buf = kmalloc(buf_len, GFP_KERNEL);
 263                 if (!pkt->buf) {
 264                         virtio_transport_free_pkt(pkt);
 265                         break;
 266                 }
 267
 268                 pkt->buf_len = buf_len;
 269                 pkt->len = buf_len;
 270
 271                 sg_init_one(&hdr, &pkt->hdr, sizeof(pkt->hdr));
 272                 sgs[0] = &hdr;
 273
 274                 sg_init_one(&buf, pkt->buf, buf_len);
 275                 sgs[1] = &buf;
 276                 ret = virtqueue_add_sgs(vq, sgs, 0, 2, pkt, GFP_KERNEL);
 277                 if (ret) {
 278                         virtio_transport_free_pkt(pkt);
 279                         break;
 280                 }
 281                 vsock->rx_buf_nr++;
 282         } while (vq->num_free);
 283         if (vsock->rx_buf_nr > vsock->rx_buf_max_nr)
 284                 vsock->rx_buf_max_nr = vsock->rx_buf_nr;
 285         virtqueue_kick(vq);
 286 }
 287
 288 static void virtio_transport_tx_work(struct work_struct *work)
 289 {
 290         struct virtio_vsock *vsock =
 291                 container_of(work, struct virtio_vsock, tx_work);
 292         struct virtqueue *vq;
 293         bool added = false;
 294
 295         vq = vsock->vqs[VSOCK_VQ_TX];
 296         mutex_lock(&vsock->tx_lock);
 297
 298         if (!vsock->tx_run)
 299                 goto out;
 300
 301         do {
 302                 struct virtio_vsock_pkt *pkt;
 303                 unsigned int len;
 304
 305                 virtqueue_disable_cb(vq);
 306                 while ((pkt = virtqueue_get_buf(vq, &len)) != NULL) {
 307                         virtio_transport_free_pkt(pkt);
 308                         added = true;
 309                 }
 310         } while (!virtqueue_enable_cb(vq));
 311
 312 out:
 313         mutex_unlock(&vsock->tx_lock);
 314
 315         if (added)
 316                 queue_work(virtio_vsock_workqueue, &vsock->send_pkt_work);
 317 }
 318
 319 /* Is there space left for replies to rx packets? */
 320 static bool virtio_transport_more_replies(struct virtio_vsock *vsock)
 321 {
 322         struct virtqueue *vq = vsock->vqs[VSOCK_VQ_RX];
 323         int val;
 324
 325         smp_rmb(); /* paired with atomic_inc() and atomic_dec_return() */
 326         val = atomic_read(&vsock->queued_replies);
 327
 328         return val < virtqueue_get_vring_size(vq);
 329 }
 330
 331 /* event_lock must be held */
 332 static int virtio_vsock_event_fill_one(struct virtio_vsock *vsock,
 333                                        struct virtio_vsock_event *event)
 334 {
 335         struct scatterlist sg;
 336         struct virtqueue *vq;
 337
 338         vq = vsock->vqs[VSOCK_VQ_EVENT];
 339
 340         sg_init_one(&sg, event, sizeof(*event));
 341
 342         return virtqueue_add_inbuf(vq, &sg, 1, event, GFP_KERNEL);
 343 }
 344
 345 /* event_lock must be held */
 346 static void virtio_vsock_event_fill(struct virtio_vsock *vsock)
 347 {
 348         size_t i;
 349
 350         for (i = 0; i < ARRAY_SIZE(vsock->event_list); i++) {
 351                 struct virtio_vsock_event *event = &vsock->event_list[i];
 352
 353                 virtio_vsock_event_fill_one(vsock, event);
 354         }
 355
 356         virtqueue_kick(vsock->vqs[VSOCK_VQ_EVENT]);
 357 }
 358
 359 static void virtio_vsock_reset_sock(struct sock *sk)
 360 {
 361         /* vmci_transport.c doesn't take sk_lock here either.  At least we're
 362          * under vsock_table_lock so the sock cannot disappear while we're
 363          * executing.
 364          */
 365
 366         sk->sk_state = TCP_CLOSE;
 367         sk->sk_err = ECONNRESET;
 368         sk_error_report(sk);
 369 }
 370
 371 static void virtio_vsock_update_guest_cid(struct virtio_vsock *vsock)
 372 {
 373         struct virtio_device *vdev = vsock->vdev;
 374         __le64 guest_cid;
 375
 376         vdev->config->get(vdev, offsetof(struct virtio_vsock_config, guest_cid),
 377                           &guest_cid, sizeof(guest_cid));
 378         vsock->guest_cid = le64_to_cpu(guest_cid);
 379 }
 380
 381 /* event_lock must be held */
 382 static void virtio_vsock_event_handle(struct virtio_vsock *vsock,
 383                                       struct virtio_vsock_event *event)
 384 {
 385         switch (le32_to_cpu(event->id)) {
 386         case VIRTIO_VSOCK_EVENT_TRANSPORT_RESET:
 387                 virtio_vsock_update_guest_cid(vsock);
 388                 vsock_for_each_connected_socket(&virtio_transport.transport,
 389                                                 virtio_vsock_reset_sock);
 390                 break;
 391         }
 392 }
 393
 394 static void virtio_transport_event_work(struct work_struct *work)
 395 {
 396         struct virtio_vsock *vsock =
 397                 container_of(work, struct virtio_vsock, event_work);
 398         struct virtqueue *vq;
 399
 400         vq = vsock->vqs[VSOCK_VQ_EVENT];
 401
 402         mutex_lock(&vsock->event_lock);
 403
 404         if (!vsock->event_run)
 405                 goto out;
 406
 407         do {
 408                 struct virtio_vsock_event *event;
 409                 unsigned int len;
 410
 411                 virtqueue_disable_cb(vq);
 412                 while ((event = virtqueue_get_buf(vq, &len)) != NULL) {
 413                         if (len == sizeof(*event))
 414                                 virtio_vsock_event_handle(vsock, event);
 415
 416                         virtio_vsock_event_fill_one(vsock, event);
 417                 }
 418         } while (!virtqueue_enable_cb(vq));
 419
 420         virtqueue_kick(vsock->vqs[VSOCK_VQ_EVENT]);
 421 out:
 422         mutex_unlock(&vsock->event_lock);
 423 }
 424
 425 static void virtio_vsock_event_done(struct virtqueue *vq)
 426 {
 427         struct virtio_vsock *vsock = vq->vdev->priv;
 428
 429         if (!vsock)
 430                 return;
 431         queue_work(virtio_vsock_workqueue, &vsock->event_work);
 432 }
 433
 434 static void virtio_vsock_tx_done(struct virtqueue *vq)
 435 {
 436         struct virtio_vsock *vsock = vq->vdev->priv;
 437
 438         if (!vsock)
 439                 return;
 440         queue_work(virtio_vsock_workqueue, &vsock->tx_work);
 441 }
 442
 443 static void virtio_vsock_rx_done(struct virtqueue *vq)
 444 {
 445         struct virtio_vsock *vsock = vq->vdev->priv;
 446
 447         if (!vsock)
 448                 return;
 449         queue_work(virtio_vsock_workqueue, &vsock->rx_work);
 450 }
 451
 452 static bool virtio_transport_seqpacket_allow(u32 remote_cid);
 453
 454 static struct virtio_transport virtio_transport = {
 455         .transport = {
 456                 .module                   = THIS_MODULE,
 457
 458                 .get_local_cid            = virtio_transport_get_local_cid,
 459
 460                 .init                     = virtio_transport_do_socket_init,
 461                 .destruct                 = virtio_transport_destruct,
 462                 .release                  = virtio_transport_release,
 463                 .connect                  = virtio_transport_connect,
 464                 .shutdown                 = virtio_transport_shutdown,
 465                 .cancel_pkt               = virtio_transport_cancel_pkt,
 466
 467                 .dgram_bind               = virtio_transport_dgram_bind,
 468                 .dgram_dequeue            = virtio_transport_dgram_dequeue,
 469                 .dgram_enqueue            = virtio_transport_dgram_enqueue,
 470                 .dgram_allow              = virtio_transport_dgram_allow,
 471
 472                 .stream_dequeue           = virtio_transport_stream_dequeue,
 473                 .stream_enqueue           = virtio_transport_stream_enqueue,
 474                 .stream_has_data          = virtio_transport_stream_has_data,
 475                 .stream_has_space         = virtio_transport_stream_has_space,
 476                 .stream_rcvhiwat          = virtio_transport_stream_rcvhiwat,
 477                 .stream_is_active         = virtio_transport_stream_is_active,
 478                 .stream_allow             = virtio_transport_stream_allow,
 479
 480                 .seqpacket_dequeue        = virtio_transport_seqpacket_dequeue,
 481                 .seqpacket_enqueue        = virtio_transport_seqpacket_enqueue,
 482                 .seqpacket_allow          = virtio_transport_seqpacket_allow,
 483                 .seqpacket_has_data       = virtio_transport_seqpacket_has_data,
 484
 485                 .notify_poll_in           = virtio_transport_notify_poll_in,
 486                 .notify_poll_out          = virtio_transport_notify_poll_out,
 487                 .notify_recv_init         = virtio_transport_notify_recv_init,
 488                 .notify_recv_pre_block    = virtio_transport_notify_recv_pre_block,
 489                 .notify_recv_pre_dequeue  = virtio_transport_notify_recv_pre_dequeue,
 490                 .notify_recv_post_dequeue = virtio_transport_notify_recv_post_dequeue,
 491                 .notify_send_init         = virtio_transport_notify_send_init,
 492                 .notify_send_pre_block    = virtio_transport_notify_send_pre_block,
 493                 .notify_send_pre_enqueue  = virtio_transport_notify_send_pre_enqueue,
 494                 .notify_send_post_enqueue = virtio_transport_notify_send_post_enqueue,
 495                 .notify_buffer_size       = virtio_transport_notify_buffer_size,
 496         },
 497
 498         .send_pkt = virtio_transport_send_pkt,
 499 };
 500
 501 static bool virtio_transport_seqpacket_allow(u32 remote_cid)
 502 {
 503         struct virtio_vsock *vsock;
 504         bool seqpacket_allow;
 505
 506         seqpacket_allow = false;
 507         rcu_read_lock();
 508         vsock = rcu_dereference(the_virtio_vsock);
 509         if (vsock)
 510                 seqpacket_allow = vsock->seqpacket_allow;
 511         rcu_read_unlock();
 512
 513         return seqpacket_allow;
 514 }
 515
 516 static void virtio_transport_rx_work(struct work_struct *work)
 517 {
 518         struct virtio_vsock *vsock =
 519                 container_of(work, struct virtio_vsock, rx_work);
 520         struct virtqueue *vq;
 521
 522         vq = vsock->vqs[VSOCK_VQ_RX];
 523
 524         mutex_lock(&vsock->rx_lock);
 525
 526         if (!vsock->rx_run)
 527                 goto out;
 528
 529         do {
 530                 virtqueue_disable_cb(vq);
 531                 for (;;) {
 532                         struct virtio_vsock_pkt *pkt;
 533                         unsigned int len;
 534
 535                         if (!virtio_transport_more_replies(vsock)) {
 536                                 /* Stop rx until the device processes already
 537                                  * pending replies.  Leave rx virtqueue
 538                                  * callbacks disabled.
 539                                  */
 540                                 goto out;
 541                         }
 542
 543                         pkt = virtqueue_get_buf(vq, &len);
 544                         if (!pkt) {
 545                                 break;
 546                         }
 547
 548                         vsock->rx_buf_nr--;
 549
 550                         /* Drop short/long packets */
 551                         if (unlikely(len < sizeof(pkt->hdr) ||
 552                                      len > sizeof(pkt->hdr) + pkt->len)) {
 553                                 virtio_transport_free_pkt(pkt);
 554                                 continue;
 555                         }
 556
 557                         pkt->len = len - sizeof(pkt->hdr);
 558                         virtio_transport_deliver_tap_pkt(pkt);
 559                         virtio_transport_recv_pkt(&virtio_transport, pkt);
 560                 }
 561         } while (!virtqueue_enable_cb(vq));
 562
 563 out:
 564         if (vsock->rx_buf_nr < vsock->rx_buf_max_nr / 2)
 565                 virtio_vsock_rx_fill(vsock);
 566         mutex_unlock(&vsock->rx_lock);
 567 }
 568
 569 static int virtio_vsock_probe(struct virtio_device *vdev)
 570 {
 571         vq_callback_t *callbacks[] = {
 572                 virtio_vsock_rx_done,
 573                 virtio_vsock_tx_done,
 574                 virtio_vsock_event_done,
 575         };
 576         static const char * const names[] = {
 577                 "rx",
 578                 "tx",
 579                 "event",
 580         };
 581         struct virtio_vsock *vsock = NULL;
 582         int ret;
 583
 584         ret = mutex_lock_interruptible(&the_virtio_vsock_mutex);
 585         if (ret)
 586                 return ret;
 587
 588         /* Only one virtio-vsock device per guest is supported */
 589         if (rcu_dereference_protected(the_virtio_vsock,
 590                                 lockdep_is_held(&the_virtio_vsock_mutex))) {
 591                 ret = -EBUSY;
 592                 goto out;
 593         }
 594
 595         vsock = kzalloc(sizeof(*vsock), GFP_KERNEL);
 596         if (!vsock) {
 597                 ret = -ENOMEM;
 598                 goto out;
 599         }
 600
 601         vsock->vdev = vdev;
 602
 603         ret = virtio_find_vqs(vsock->vdev, VSOCK_VQ_MAX,
 604                               vsock->vqs, callbacks, names,
 605                               NULL);
 606         if (ret < 0)
 607                 goto out;
 608
 609         virtio_vsock_update_guest_cid(vsock);
 610
 611         vsock->rx_buf_nr = 0;
 612         vsock->rx_buf_max_nr = 0;
 613         atomic_set(&vsock->queued_replies, 0);
 614
 615         mutex_init(&vsock->tx_lock);
 616         mutex_init(&vsock->rx_lock);
 617         mutex_init(&vsock->event_lock);
 618         spin_lock_init(&vsock->send_pkt_list_lock);
 619         INIT_LIST_HEAD(&vsock->send_pkt_list);
 620         INIT_WORK(&vsock->rx_work, virtio_transport_rx_work);
 621         INIT_WORK(&vsock->tx_work, virtio_transport_tx_work);
 622         INIT_WORK(&vsock->event_work, virtio_transport_event_work);
 623         INIT_WORK(&vsock->send_pkt_work, virtio_transport_send_pkt_work);
 624
 625         vdev->priv = vsock;
 626
 627         mutex_lock(&vsock->tx_lock);
 628         vsock->tx_run = true;
 629         mutex_unlock(&vsock->tx_lock);
 630
 631         mutex_lock(&vsock->rx_lock);
 632         virtio_vsock_rx_fill(vsock);
 633         vsock->rx_run = true;
 634         mutex_unlock(&vsock->rx_lock);
 635
 636         mutex_lock(&vsock->event_lock);
 637         virtio_vsock_event_fill(vsock);
 638         vsock->event_run = true;
 639         mutex_unlock(&vsock->event_lock);
 640
 641         if (virtio_has_feature(vdev, VIRTIO_VSOCK_F_SEQPACKET))
 642                 vsock->seqpacket_allow = true;
 643
 644         rcu_assign_pointer(the_virtio_vsock, vsock);
 645
 646         mutex_unlock(&the_virtio_vsock_mutex);
 647
 648         return 0;
 649
 650 out:
 651         kfree(vsock);
 652         mutex_unlock(&the_virtio_vsock_mutex);
 653         return ret;
 654 }
 655
 656 static void virtio_vsock_remove(struct virtio_device *vdev)
 657 {
 658         struct virtio_vsock *vsock = vdev->priv;
 659         struct virtio_vsock_pkt *pkt;
 660
 661         mutex_lock(&the_virtio_vsock_mutex);
 662
 663         vdev->priv = NULL;
 664         rcu_assign_pointer(the_virtio_vsock, NULL);
 665         synchronize_rcu();
 666
 667         /* Reset all connected sockets when the device disappear */
 668         vsock_for_each_connected_socket(&virtio_transport.transport,
 669                                         virtio_vsock_reset_sock);
 670
 671         /* Stop all work handlers to make sure no one is accessing the device,
 672          * so we can safely call vdev->config->reset().
 673          */
 674         mutex_lock(&vsock->rx_lock);
 675         vsock->rx_run = false;
 676         mutex_unlock(&vsock->rx_lock);
 677
 678         mutex_lock(&vsock->tx_lock);
 679         vsock->tx_run = false;
 680         mutex_unlock(&vsock->tx_lock);
 681
 682         mutex_lock(&vsock->event_lock);
 683         vsock->event_run = false;
 684         mutex_unlock(&vsock->event_lock);
 685
 686         /* Flush all device writes and interrupts, device will not use any
 687          * more buffers.
 688          */
 689         vdev->config->reset(vdev);
 690
 691         mutex_lock(&vsock->rx_lock);
 692         while ((pkt = virtqueue_detach_unused_buf(vsock->vqs[VSOCK_VQ_RX])))
 693                 virtio_transport_free_pkt(pkt);
 694         mutex_unlock(&vsock->rx_lock);
 695
 696         mutex_lock(&vsock->tx_lock);
 697         while ((pkt = virtqueue_detach_unused_buf(vsock->vqs[VSOCK_VQ_TX])))
 698                 virtio_transport_free_pkt(pkt);
 699         mutex_unlock(&vsock->tx_lock);
 700
 701         spin_lock_bh(&vsock->send_pkt_list_lock);
 702         while (!list_empty(&vsock->send_pkt_list)) {
 703                 pkt = list_first_entry(&vsock->send_pkt_list,
 704                                        struct virtio_vsock_pkt, list);
 705                 list_del(&pkt->list);
 706                 virtio_transport_free_pkt(pkt);
 707         }
 708         spin_unlock_bh(&vsock->send_pkt_list_lock);
 709
 710         /* Delete virtqueues and flush outstanding callbacks if any */
 711         vdev->config->del_vqs(vdev);
 712
 713         /* Other works can be queued before 'config->del_vqs()', so we flush
 714          * all works before to free the vsock object to avoid use after free.
 715          */
 716         flush_work(&vsock->rx_work);
 717         flush_work(&vsock->tx_work);
 718         flush_work(&vsock->event_work);
 719         flush_work(&vsock->send_pkt_work);
 720
 721         mutex_unlock(&the_virtio_vsock_mutex);
 722
 723         kfree(vsock);
 724 }
 725
 726 static struct virtio_device_id id_table[] = {
 727         { VIRTIO_ID_VSOCK, VIRTIO_DEV_ANY_ID },
 728         { 0 },
 729 };
 730
 731 static unsigned int features[] = {
 732         VIRTIO_VSOCK_F_SEQPACKET
 733 };
 734
 735 static struct virtio_driver virtio_vsock_driver = {
 736         .feature_table = features,
 737         .feature_table_size = ARRAY_SIZE(features),
 738         .driver.name = KBUILD_MODNAME,
 739         .driver.owner = THIS_MODULE,
 740         .id_table = id_table,
 741         .probe = virtio_vsock_probe,
 742         .remove = virtio_vsock_remove,
 743 };
 744
 745 static int __init virtio_vsock_init(void)
 746 {
 747         int ret;
 748
 749         virtio_vsock_workqueue = alloc_workqueue("virtio_vsock", 0, 0);
 750         if (!virtio_vsock_workqueue)
 751                 return -ENOMEM;
 752
 753         ret = vsock_core_register(&virtio_transport.transport,
 754                                   VSOCK_TRANSPORT_F_G2H);
 755         if (ret)
 756                 goto out_wq;
 757
 758         ret = register_virtio_driver(&virtio_vsock_driver);
 759         if (ret)
 760                 goto out_vci;
 761
 762         return 0;
 763
 764 out_vci:
 765         vsock_core_unregister(&virtio_transport.transport);
 766 out_wq:
 767         destroy_workqueue(virtio_vsock_workqueue);
 768         return ret;
 769 }
 770
 771 static void __exit virtio_vsock_exit(void)
 772 {
 773         unregister_virtio_driver(&virtio_vsock_driver);
 774         vsock_core_unregister(&virtio_transport.transport);
 775         destroy_workqueue(virtio_vsock_workqueue);
 776 }
 777
 778 module_init(virtio_vsock_init);
 779 module_exit(virtio_vsock_exit);
 780 MODULE_LICENSE("GPL v2");
 781 MODULE_AUTHOR("Asias He");
 782 MODULE_DESCRIPTION("virtio transport for vsock");
 783 MODULE_DEVICE_TABLE(virtio, id_table);