vsock.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * vhost 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 #include <linux/miscdevice.h>
  10 #include <linux/atomic.h>
  11 #include <linux/module.h>
  12 #include <linux/mutex.h>
  13 #include <linux/vmalloc.h>
  14 #include <net/sock.h>
  15 #include <linux/virtio_vsock.h>
  16 #include <linux/vhost.h>
  17 #include <linux/hashtable.h>
  18
  19 #include <net/af_vsock.h>
  20 #include "vhost.h"
  21
  22 #define VHOST_VSOCK_DEFAULT_HOST_CID    2
  23 /* Max number of bytes transferred before requeueing the job.
  24  * Using this limit prevents one virtqueue from starving others. */
  25 #define VHOST_VSOCK_WEIGHT 0x80000
  26 /* Max number of packets transferred before requeueing the job.
  27  * Using this limit prevents one virtqueue from starving others with
  28  * small pkts.
  29  */
  30 #define VHOST_VSOCK_PKT_WEIGHT 256
  31
  32 enum {
  33         VHOST_VSOCK_FEATURES = VHOST_FEATURES |
  34                                (1ULL << VIRTIO_F_ACCESS_PLATFORM) |
  35                                (1ULL << VIRTIO_VSOCK_F_SEQPACKET)
  36 };
  37
  38 enum {
  39         VHOST_VSOCK_BACKEND_FEATURES = (1ULL << VHOST_BACKEND_F_IOTLB_MSG_V2)
  40 };
  41
  42 /* Used to track all the vhost_vsock instances on the system. */
  43 static DEFINE_MUTEX(vhost_vsock_mutex);
  44 static DEFINE_READ_MOSTLY_HASHTABLE(vhost_vsock_hash, 8);
  45
  46 struct vhost_vsock {
  47         struct vhost_dev dev;
  48         struct vhost_virtqueue vqs[2];
  49
  50         /* Link to global vhost_vsock_hash, writes use vhost_vsock_mutex */
  51         struct hlist_node hash;
  52
  53         struct vhost_work send_pkt_work;
  54         struct sk_buff_head send_pkt_queue; /* host->guest pending packets */
  55
  56         atomic_t queued_replies;
  57
  58         u32 guest_cid;
  59         bool seqpacket_allow;
  60 };
  61
  62 static u32 vhost_transport_get_local_cid(void)
  63 {
  64         return VHOST_VSOCK_DEFAULT_HOST_CID;
  65 }
  66
  67 /* Callers that dereference the return value must hold vhost_vsock_mutex or the
  68  * RCU read lock.
  69  */
  70 static struct vhost_vsock *vhost_vsock_get(u32 guest_cid)
  71 {
  72         struct vhost_vsock *vsock;
  73
  74         hash_for_each_possible_rcu(vhost_vsock_hash, vsock, hash, guest_cid) {
  75                 u32 other_cid = vsock->guest_cid;
  76
  77                 /* Skip instances that have no CID yet */
  78                 if (other_cid == 0)
  79                         continue;
  80
  81                 if (other_cid == guest_cid)
  82                         return vsock;
  83
  84         }
  85
  86         return NULL;
  87 }
  88
  89 static void
  90 vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
  91                             struct vhost_virtqueue *vq)
  92 {
  93         struct vhost_virtqueue *tx_vq = &vsock->vqs[VSOCK_VQ_TX];
  94         int pkts = 0, total_len = 0;
  95         bool added = false;
  96         bool restart_tx = false;
  97
  98         mutex_lock(&vq->mutex);
  99
 100         if (!vhost_vq_get_backend(vq))
 101                 goto out;
 102
 103         if (!vq_meta_prefetch(vq))
 104                 goto out;
 105
 106         /* Avoid further vmexits, we're already processing the virtqueue */
 107         vhost_disable_notify(&vsock->dev, vq);
 108
 109         do {
 110                 struct virtio_vsock_hdr *hdr;
 111                 size_t iov_len, payload_len;
 112                 struct iov_iter iov_iter;
 113                 u32 flags_to_restore = 0;
 114                 struct sk_buff *skb;
 115                 unsigned out, in;
 116                 size_t nbytes;
 117                 u32 offset;
 118                 int head;
 119
 120                 skb = virtio_vsock_skb_dequeue(&vsock->send_pkt_queue);
 121
 122                 if (!skb) {
 123                         vhost_enable_notify(&vsock->dev, vq);
 124                         break;
 125                 }
 126
 127                 head = vhost_get_vq_desc(vq, vq->iov, ARRAY_SIZE(vq->iov),
 128                                          &out, &in, NULL, NULL);
 129                 if (head < 0) {
 130                         virtio_vsock_skb_queue_head(&vsock->send_pkt_queue, skb);
 131                         break;
 132                 }
 133
 134                 if (head == vq->num) {
 135                         virtio_vsock_skb_queue_head(&vsock->send_pkt_queue, skb);
 136                         /* We cannot finish yet if more buffers snuck in while
 137                          * re-enabling notify.
 138                          */
 139                         if (unlikely(vhost_enable_notify(&vsock->dev, vq))) {
 140                                 vhost_disable_notify(&vsock->dev, vq);
 141                                 continue;
 142                         }
 143                         break;
 144                 }
 145
 146                 if (out) {
 147                         kfree_skb(skb);
 148                         vq_err(vq, "Expected 0 output buffers, got %u\n", out);
 149                         break;
 150                 }
 151
 152                 iov_len = iov_length(&vq->iov[out], in);
 153                 if (iov_len < sizeof(*hdr)) {
 154                         kfree_skb(skb);
 155                         vq_err(vq, "Buffer len [%zu] too small\n", iov_len);
 156                         break;
 157                 }
 158
 159                 iov_iter_init(&iov_iter, ITER_DEST, &vq->iov[out], in, iov_len);
 160                 offset = VIRTIO_VSOCK_SKB_CB(skb)->offset;
 161                 payload_len = skb->len - offset;
 162                 hdr = virtio_vsock_hdr(skb);
 163
 164                 /* If the packet is greater than the space available in the
 165                  * buffer, we split it using multiple buffers.
 166                  */
 167                 if (payload_len > iov_len - sizeof(*hdr)) {
 168                         payload_len = iov_len - sizeof(*hdr);
 169
 170                         /* As we are copying pieces of large packet's buffer to
 171                          * small rx buffers, headers of packets in rx queue are
 172                          * created dynamically and are initialized with header
 173                          * of current packet(except length). But in case of
 174                          * SOCK_SEQPACKET, we also must clear message delimeter
 175                          * bit (VIRTIO_VSOCK_SEQ_EOM) and MSG_EOR bit
 176                          * (VIRTIO_VSOCK_SEQ_EOR) if set. Otherwise,
 177                          * there will be sequence of packets with these
 178                          * bits set. After initialized header will be copied to
 179                          * rx buffer, these required bits will be restored.
 180                          */
 181                         if (le32_to_cpu(hdr->flags) & VIRTIO_VSOCK_SEQ_EOM) {
 182                                 hdr->flags &= ~cpu_to_le32(VIRTIO_VSOCK_SEQ_EOM);
 183                                 flags_to_restore |= VIRTIO_VSOCK_SEQ_EOM;
 184
 185                                 if (le32_to_cpu(hdr->flags) & VIRTIO_VSOCK_SEQ_EOR) {
 186                                         hdr->flags &= ~cpu_to_le32(VIRTIO_VSOCK_SEQ_EOR);
 187                                         flags_to_restore |= VIRTIO_VSOCK_SEQ_EOR;
 188                                 }
 189                         }
 190                 }
 191
 192                 /* Set the correct length in the header */
 193                 hdr->len = cpu_to_le32(payload_len);
 194
 195                 nbytes = copy_to_iter(hdr, sizeof(*hdr), &iov_iter);
 196                 if (nbytes != sizeof(*hdr)) {
 197                         kfree_skb(skb);
 198                         vq_err(vq, "Faulted on copying pkt hdr\n");
 199                         break;
 200                 }
 201
 202                 if (skb_copy_datagram_iter(skb,
 203                                            offset,
 204                                            &iov_iter,
 205                                            payload_len)) {
 206                         kfree_skb(skb);
 207                         vq_err(vq, "Faulted on copying pkt buf\n");
 208                         break;
 209                 }
 210
 211                 /* Deliver to monitoring devices all packets that we
 212                  * will transmit.
 213                  */
 214                 virtio_transport_deliver_tap_pkt(skb);
 215
 216                 vhost_add_used(vq, head, sizeof(*hdr) + payload_len);
 217                 added = true;
 218
 219                 VIRTIO_VSOCK_SKB_CB(skb)->offset += payload_len;
 220                 total_len += payload_len;
 221
 222                 /* If we didn't send all the payload we can requeue the packet
 223                  * to send it with the next available buffer.
 224                  */
 225                 if (VIRTIO_VSOCK_SKB_CB(skb)->offset < skb->len) {
 226                         hdr->flags |= cpu_to_le32(flags_to_restore);
 227
 228                         /* We are queueing the same skb to handle
 229                          * the remaining bytes, and we want to deliver it
 230                          * to monitoring devices in the next iteration.
 231                          */
 232                         virtio_vsock_skb_clear_tap_delivered(skb);
 233                         virtio_vsock_skb_queue_head(&vsock->send_pkt_queue, skb);
 234                 } else {
 235                         if (virtio_vsock_skb_reply(skb)) {
 236                                 int val;
 237
 238                                 val = atomic_dec_return(&vsock->queued_replies);
 239
 240                                 /* Do we have resources to resume tx
 241                                  * processing?
 242                                  */
 243                                 if (val + 1 == tx_vq->num)
 244                                         restart_tx = true;
 245                         }
 246
 247                         consume_skb(skb);
 248                 }
 249         } while(likely(!vhost_exceeds_weight(vq, ++pkts, total_len)));
 250         if (added)
 251                 vhost_signal(&vsock->dev, vq);
 252
 253 out:
 254         mutex_unlock(&vq->mutex);
 255
 256         if (restart_tx)
 257                 vhost_poll_queue(&tx_vq->poll);
 258 }
 259
 260 static void vhost_transport_send_pkt_work(struct vhost_work *work)
 261 {
 262         struct vhost_virtqueue *vq;
 263         struct vhost_vsock *vsock;
 264
 265         vsock = container_of(work, struct vhost_vsock, send_pkt_work);
 266         vq = &vsock->vqs[VSOCK_VQ_RX];
 267
 268         vhost_transport_do_send_pkt(vsock, vq);
 269 }
 270
 271 static int
 272 vhost_transport_send_pkt(struct sk_buff *skb)
 273 {
 274         struct virtio_vsock_hdr *hdr = virtio_vsock_hdr(skb);
 275         struct vhost_vsock *vsock;
 276         int len = skb->len;
 277
 278         rcu_read_lock();
 279
 280         /* Find the vhost_vsock according to guest context id  */
 281         vsock = vhost_vsock_get(le64_to_cpu(hdr->dst_cid));
 282         if (!vsock) {
 283                 rcu_read_unlock();
 284                 kfree_skb(skb);
 285                 return -ENODEV;
 286         }
 287
 288         if (virtio_vsock_skb_reply(skb))
 289                 atomic_inc(&vsock->queued_replies);
 290
 291         virtio_vsock_skb_queue_tail(&vsock->send_pkt_queue, skb);
 292         vhost_vq_work_queue(&vsock->vqs[VSOCK_VQ_RX], &vsock->send_pkt_work);
 293
 294         rcu_read_unlock();
 295         return len;
 296 }
 297
 298 static int
 299 vhost_transport_cancel_pkt(struct vsock_sock *vsk)
 300 {
 301         struct vhost_vsock *vsock;
 302         int cnt = 0;
 303         int ret = -ENODEV;
 304
 305         rcu_read_lock();
 306
 307         /* Find the vhost_vsock according to guest context id  */
 308         vsock = vhost_vsock_get(vsk->remote_addr.svm_cid);
 309         if (!vsock)
 310                 goto out;
 311
 312         cnt = virtio_transport_purge_skbs(vsk, &vsock->send_pkt_queue);
 313
 314         if (cnt) {
 315                 struct vhost_virtqueue *tx_vq = &vsock->vqs[VSOCK_VQ_TX];
 316                 int new_cnt;
 317
 318                 new_cnt = atomic_sub_return(cnt, &vsock->queued_replies);
 319                 if (new_cnt + cnt >= tx_vq->num && new_cnt < tx_vq->num)
 320                         vhost_poll_queue(&tx_vq->poll);
 321         }
 322
 323         ret = 0;
 324 out:
 325         rcu_read_unlock();
 326         return ret;
 327 }
 328
 329 static struct sk_buff *
 330 vhost_vsock_alloc_skb(struct vhost_virtqueue *vq,
 331                       unsigned int out, unsigned int in)
 332 {
 333         struct virtio_vsock_hdr *hdr;
 334         struct iov_iter iov_iter;
 335         struct sk_buff *skb;
 336         size_t payload_len;
 337         size_t nbytes;
 338         size_t len;
 339
 340         if (in != 0) {
 341                 vq_err(vq, "Expected 0 input buffers, got %u\n", in);
 342                 return NULL;
 343         }
 344
 345         len = iov_length(vq->iov, out);
 346
 347         /* len contains both payload and hdr */
 348         skb = virtio_vsock_alloc_skb(len, GFP_KERNEL);
 349         if (!skb)
 350                 return NULL;
 351
 352         iov_iter_init(&iov_iter, ITER_SOURCE, vq->iov, out, len);
 353
 354         hdr = virtio_vsock_hdr(skb);
 355         nbytes = copy_from_iter(hdr, sizeof(*hdr), &iov_iter);
 356         if (nbytes != sizeof(*hdr)) {
 357                 vq_err(vq, "Expected %zu bytes for pkt->hdr, got %zu bytes\n",
 358                        sizeof(*hdr), nbytes);
 359                 kfree_skb(skb);
 360                 return NULL;
 361         }
 362
 363         payload_len = le32_to_cpu(hdr->len);
 364
 365         /* No payload */
 366         if (!payload_len)
 367                 return skb;
 368
 369         /* The pkt is too big or the length in the header is invalid */
 370         if (payload_len > VIRTIO_VSOCK_MAX_PKT_BUF_SIZE ||
 371             payload_len + sizeof(*hdr) > len) {
 372                 kfree_skb(skb);
 373                 return NULL;
 374         }
 375
 376         virtio_vsock_skb_rx_put(skb);
 377
 378         nbytes = copy_from_iter(skb->data, payload_len, &iov_iter);
 379         if (nbytes != payload_len) {
 380                 vq_err(vq, "Expected %zu byte payload, got %zu bytes\n",
 381                        payload_len, nbytes);
 382                 kfree_skb(skb);
 383                 return NULL;
 384         }
 385
 386         return skb;
 387 }
 388
 389 /* Is there space left for replies to rx packets? */
 390 static bool vhost_vsock_more_replies(struct vhost_vsock *vsock)
 391 {
 392         struct vhost_virtqueue *vq = &vsock->vqs[VSOCK_VQ_TX];
 393         int val;
 394
 395         smp_rmb(); /* paired with atomic_inc() and atomic_dec_return() */
 396         val = atomic_read(&vsock->queued_replies);
 397
 398         return val < vq->num;
 399 }
 400
 401 static bool vhost_transport_msgzerocopy_allow(void)
 402 {
 403         return true;
 404 }
 405
 406 static bool vhost_transport_seqpacket_allow(u32 remote_cid);
 407
 408 static struct virtio_transport vhost_transport = {
 409         .transport = {
 410                 .module                   = THIS_MODULE,
 411
 412                 .get_local_cid            = vhost_transport_get_local_cid,
 413
 414                 .init                     = virtio_transport_do_socket_init,
 415                 .destruct                 = virtio_transport_destruct,
 416                 .release                  = virtio_transport_release,
 417                 .connect                  = virtio_transport_connect,
 418                 .shutdown                 = virtio_transport_shutdown,
 419                 .cancel_pkt               = vhost_transport_cancel_pkt,
 420
 421                 .dgram_enqueue            = virtio_transport_dgram_enqueue,
 422                 .dgram_dequeue            = virtio_transport_dgram_dequeue,
 423                 .dgram_bind               = virtio_transport_dgram_bind,
 424                 .dgram_allow              = virtio_transport_dgram_allow,
 425
 426                 .stream_enqueue           = virtio_transport_stream_enqueue,
 427                 .stream_dequeue           = virtio_transport_stream_dequeue,
 428                 .stream_has_data          = virtio_transport_stream_has_data,
 429                 .stream_has_space         = virtio_transport_stream_has_space,
 430                 .stream_rcvhiwat          = virtio_transport_stream_rcvhiwat,
 431                 .stream_is_active         = virtio_transport_stream_is_active,
 432                 .stream_allow             = virtio_transport_stream_allow,
 433
 434                 .seqpacket_dequeue        = virtio_transport_seqpacket_dequeue,
 435                 .seqpacket_enqueue        = virtio_transport_seqpacket_enqueue,
 436                 .seqpacket_allow          = vhost_transport_seqpacket_allow,
 437                 .seqpacket_has_data       = virtio_transport_seqpacket_has_data,
 438
 439                 .msgzerocopy_allow        = vhost_transport_msgzerocopy_allow,
 440
 441                 .notify_poll_in           = virtio_transport_notify_poll_in,
 442                 .notify_poll_out          = virtio_transport_notify_poll_out,
 443                 .notify_recv_init         = virtio_transport_notify_recv_init,
 444                 .notify_recv_pre_block    = virtio_transport_notify_recv_pre_block,
 445                 .notify_recv_pre_dequeue  = virtio_transport_notify_recv_pre_dequeue,
 446                 .notify_recv_post_dequeue = virtio_transport_notify_recv_post_dequeue,
 447                 .notify_send_init         = virtio_transport_notify_send_init,
 448                 .notify_send_pre_block    = virtio_transport_notify_send_pre_block,
 449                 .notify_send_pre_enqueue  = virtio_transport_notify_send_pre_enqueue,
 450                 .notify_send_post_enqueue = virtio_transport_notify_send_post_enqueue,
 451                 .notify_buffer_size       = virtio_transport_notify_buffer_size,
 452                 .notify_set_rcvlowat      = virtio_transport_notify_set_rcvlowat,
 453
 454                 .read_skb = virtio_transport_read_skb,
 455         },
 456
 457         .send_pkt = vhost_transport_send_pkt,
 458 };
 459
 460 static bool vhost_transport_seqpacket_allow(u32 remote_cid)
 461 {
 462         struct vhost_vsock *vsock;
 463         bool seqpacket_allow = false;
 464
 465         rcu_read_lock();
 466         vsock = vhost_vsock_get(remote_cid);
 467
 468         if (vsock)
 469                 seqpacket_allow = vsock->seqpacket_allow;
 470
 471         rcu_read_unlock();
 472
 473         return seqpacket_allow;
 474 }
 475
 476 static void vhost_vsock_handle_tx_kick(struct vhost_work *work)
 477 {
 478         struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
 479                                                   poll.work);
 480         struct vhost_vsock *vsock = container_of(vq->dev, struct vhost_vsock,
 481                                                  dev);
 482         int head, pkts = 0, total_len = 0;
 483         unsigned int out, in;
 484         struct sk_buff *skb;
 485         bool added = false;
 486
 487         mutex_lock(&vq->mutex);
 488
 489         if (!vhost_vq_get_backend(vq))
 490                 goto out;
 491
 492         if (!vq_meta_prefetch(vq))
 493                 goto out;
 494
 495         vhost_disable_notify(&vsock->dev, vq);
 496         do {
 497                 struct virtio_vsock_hdr *hdr;
 498
 499                 if (!vhost_vsock_more_replies(vsock)) {
 500                         /* Stop tx until the device processes already
 501                          * pending replies.  Leave tx virtqueue
 502                          * callbacks disabled.
 503                          */
 504                         goto no_more_replies;
 505                 }
 506
 507                 head = vhost_get_vq_desc(vq, vq->iov, ARRAY_SIZE(vq->iov),
 508                                          &out, &in, NULL, NULL);
 509                 if (head < 0)
 510                         break;
 511
 512                 if (head == vq->num) {
 513                         if (unlikely(vhost_enable_notify(&vsock->dev, vq))) {
 514                                 vhost_disable_notify(&vsock->dev, vq);
 515                                 continue;
 516                         }
 517                         break;
 518                 }
 519
 520                 skb = vhost_vsock_alloc_skb(vq, out, in);
 521                 if (!skb) {
 522                         vq_err(vq, "Faulted on pkt\n");
 523                         continue;
 524                 }
 525
 526                 total_len += sizeof(*hdr) + skb->len;
 527
 528                 /* Deliver to monitoring devices all received packets */
 529                 virtio_transport_deliver_tap_pkt(skb);
 530
 531                 hdr = virtio_vsock_hdr(skb);
 532
 533                 /* Only accept correctly addressed packets */
 534                 if (le64_to_cpu(hdr->src_cid) == vsock->guest_cid &&
 535                     le64_to_cpu(hdr->dst_cid) ==
 536                     vhost_transport_get_local_cid())
 537                         virtio_transport_recv_pkt(&vhost_transport, skb);
 538                 else
 539                         kfree_skb(skb);
 540
 541                 vhost_add_used(vq, head, 0);
 542                 added = true;
 543         } while(likely(!vhost_exceeds_weight(vq, ++pkts, total_len)));
 544
 545 no_more_replies:
 546         if (added)
 547                 vhost_signal(&vsock->dev, vq);
 548
 549 out:
 550         mutex_unlock(&vq->mutex);
 551 }
 552
 553 static void vhost_vsock_handle_rx_kick(struct vhost_work *work)
 554 {
 555         struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
 556                                                 poll.work);
 557         struct vhost_vsock *vsock = container_of(vq->dev, struct vhost_vsock,
 558                                                  dev);
 559
 560         vhost_transport_do_send_pkt(vsock, vq);
 561 }
 562
 563 static int vhost_vsock_start(struct vhost_vsock *vsock)
 564 {
 565         struct vhost_virtqueue *vq;
 566         size_t i;
 567         int ret;
 568
 569         mutex_lock(&vsock->dev.mutex);
 570
 571         ret = vhost_dev_check_owner(&vsock->dev);
 572         if (ret)
 573                 goto err;
 574
 575         for (i = 0; i < ARRAY_SIZE(vsock->vqs); i++) {
 576                 vq = &vsock->vqs[i];
 577
 578                 mutex_lock(&vq->mutex);
 579
 580                 if (!vhost_vq_access_ok(vq)) {
 581                         ret = -EFAULT;
 582                         goto err_vq;
 583                 }
 584
 585                 if (!vhost_vq_get_backend(vq)) {
 586                         vhost_vq_set_backend(vq, vsock);
 587                         ret = vhost_vq_init_access(vq);
 588                         if (ret)
 589                                 goto err_vq;
 590                 }
 591
 592                 mutex_unlock(&vq->mutex);
 593         }
 594
 595         /* Some packets may have been queued before the device was started,
 596          * let's kick the send worker to send them.
 597          */
 598         vhost_vq_work_queue(&vsock->vqs[VSOCK_VQ_RX], &vsock->send_pkt_work);
 599
 600         mutex_unlock(&vsock->dev.mutex);
 601         return 0;
 602
 603 err_vq:
 604         vhost_vq_set_backend(vq, NULL);
 605         mutex_unlock(&vq->mutex);
 606
 607         for (i = 0; i < ARRAY_SIZE(vsock->vqs); i++) {
 608                 vq = &vsock->vqs[i];
 609
 610                 mutex_lock(&vq->mutex);
 611                 vhost_vq_set_backend(vq, NULL);
 612                 mutex_unlock(&vq->mutex);
 613         }
 614 err:
 615         mutex_unlock(&vsock->dev.mutex);
 616         return ret;
 617 }
 618
 619 static int vhost_vsock_stop(struct vhost_vsock *vsock, bool check_owner)
 620 {
 621         size_t i;
 622         int ret = 0;
 623
 624         mutex_lock(&vsock->dev.mutex);
 625
 626         if (check_owner) {
 627                 ret = vhost_dev_check_owner(&vsock->dev);
 628                 if (ret)
 629                         goto err;
 630         }
 631
 632         for (i = 0; i < ARRAY_SIZE(vsock->vqs); i++) {
 633                 struct vhost_virtqueue *vq = &vsock->vqs[i];
 634
 635                 mutex_lock(&vq->mutex);
 636                 vhost_vq_set_backend(vq, NULL);
 637                 mutex_unlock(&vq->mutex);
 638         }
 639
 640 err:
 641         mutex_unlock(&vsock->dev.mutex);
 642         return ret;
 643 }
 644
 645 static void vhost_vsock_free(struct vhost_vsock *vsock)
 646 {
 647         kvfree(vsock);
 648 }
 649
 650 static int vhost_vsock_dev_open(struct inode *inode, struct file *file)
 651 {
 652         struct vhost_virtqueue **vqs;
 653         struct vhost_vsock *vsock;
 654         int ret;
 655
 656         /* This struct is large and allocation could fail, fall back to vmalloc
 657          * if there is no other way.
 658          */
 659         vsock = kvmalloc(sizeof(*vsock), GFP_KERNEL | __GFP_RETRY_MAYFAIL);
 660         if (!vsock)
 661                 return -ENOMEM;
 662
 663         vqs = kmalloc_array(ARRAY_SIZE(vsock->vqs), sizeof(*vqs), GFP_KERNEL);
 664         if (!vqs) {
 665                 ret = -ENOMEM;
 666                 goto out;
 667         }
 668
 669         vsock->guest_cid = 0; /* no CID assigned yet */
 670
 671         atomic_set(&vsock->queued_replies, 0);
 672
 673         vqs[VSOCK_VQ_TX] = &vsock->vqs[VSOCK_VQ_TX];
 674         vqs[VSOCK_VQ_RX] = &vsock->vqs[VSOCK_VQ_RX];
 675         vsock->vqs[VSOCK_VQ_TX].handle_kick = vhost_vsock_handle_tx_kick;
 676         vsock->vqs[VSOCK_VQ_RX].handle_kick = vhost_vsock_handle_rx_kick;
 677
 678         vhost_dev_init(&vsock->dev, vqs, ARRAY_SIZE(vsock->vqs),
 679                        UIO_MAXIOV, VHOST_VSOCK_PKT_WEIGHT,
 680                        VHOST_VSOCK_WEIGHT, true, NULL);
 681
 682         file->private_data = vsock;
 683         skb_queue_head_init(&vsock->send_pkt_queue);
 684         vhost_work_init(&vsock->send_pkt_work, vhost_transport_send_pkt_work);
 685         return 0;
 686
 687 out:
 688         vhost_vsock_free(vsock);
 689         return ret;
 690 }
 691
 692 static void vhost_vsock_flush(struct vhost_vsock *vsock)
 693 {
 694         vhost_dev_flush(&vsock->dev);
 695 }
 696
 697 static void vhost_vsock_reset_orphans(struct sock *sk)
 698 {
 699         struct vsock_sock *vsk = vsock_sk(sk);
 700
 701         /* vmci_transport.c doesn't take sk_lock here either.  At least we're
 702          * under vsock_table_lock so the sock cannot disappear while we're
 703          * executing.
 704          */
 705
 706         /* If the peer is still valid, no need to reset connection */
 707         if (vhost_vsock_get(vsk->remote_addr.svm_cid))
 708                 return;
 709
 710         /* If the close timeout is pending, let it expire.  This avoids races
 711          * with the timeout callback.
 712          */
 713         if (vsk->close_work_scheduled)
 714                 return;
 715
 716         sock_set_flag(sk, SOCK_DONE);
 717         vsk->peer_shutdown = SHUTDOWN_MASK;
 718         sk->sk_state = SS_UNCONNECTED;
 719         sk->sk_err = ECONNRESET;
 720         sk_error_report(sk);
 721 }
 722
 723 static int vhost_vsock_dev_release(struct inode *inode, struct file *file)
 724 {
 725         struct vhost_vsock *vsock = file->private_data;
 726
 727         mutex_lock(&vhost_vsock_mutex);
 728         if (vsock->guest_cid)
 729                 hash_del_rcu(&vsock->hash);
 730         mutex_unlock(&vhost_vsock_mutex);
 731
 732         /* Wait for other CPUs to finish using vsock */
 733         synchronize_rcu();
 734
 735         /* Iterating over all connections for all CIDs to find orphans is
 736          * inefficient.  Room for improvement here. */
 737         vsock_for_each_connected_socket(&vhost_transport.transport,
 738                                         vhost_vsock_reset_orphans);
 739
 740         /* Don't check the owner, because we are in the release path, so we
 741          * need to stop the vsock device in any case.
 742          * vhost_vsock_stop() can not fail in this case, so we don't need to
 743          * check the return code.
 744          */
 745         vhost_vsock_stop(vsock, false);
 746         vhost_vsock_flush(vsock);
 747         vhost_dev_stop(&vsock->dev);
 748
 749         virtio_vsock_skb_queue_purge(&vsock->send_pkt_queue);
 750
 751         vhost_dev_cleanup(&vsock->dev);
 752         kfree(vsock->dev.vqs);
 753         vhost_vsock_free(vsock);
 754         return 0;
 755 }
 756
 757 static int vhost_vsock_set_cid(struct vhost_vsock *vsock, u64 guest_cid)
 758 {
 759         struct vhost_vsock *other;
 760
 761         /* Refuse reserved CIDs */
 762         if (guest_cid <= VMADDR_CID_HOST ||
 763             guest_cid == U32_MAX)
 764                 return -EINVAL;
 765
 766         /* 64-bit CIDs are not yet supported */
 767         if (guest_cid > U32_MAX)
 768                 return -EINVAL;
 769
 770         /* Refuse if CID is assigned to the guest->host transport (i.e. nested
 771          * VM), to make the loopback work.
 772          */
 773         if (vsock_find_cid(guest_cid))
 774                 return -EADDRINUSE;
 775
 776         /* Refuse if CID is already in use */
 777         mutex_lock(&vhost_vsock_mutex);
 778         other = vhost_vsock_get(guest_cid);
 779         if (other && other != vsock) {
 780                 mutex_unlock(&vhost_vsock_mutex);
 781                 return -EADDRINUSE;
 782         }
 783
 784         if (vsock->guest_cid)
 785                 hash_del_rcu(&vsock->hash);
 786
 787         vsock->guest_cid = guest_cid;
 788         hash_add_rcu(vhost_vsock_hash, &vsock->hash, vsock->guest_cid);
 789         mutex_unlock(&vhost_vsock_mutex);
 790
 791         return 0;
 792 }
 793
 794 static int vhost_vsock_set_features(struct vhost_vsock *vsock, u64 features)
 795 {
 796         struct vhost_virtqueue *vq;
 797         int i;
 798
 799         if (features & ~VHOST_VSOCK_FEATURES)
 800                 return -EOPNOTSUPP;
 801
 802         mutex_lock(&vsock->dev.mutex);
 803         if ((features & (1 << VHOST_F_LOG_ALL)) &&
 804             !vhost_log_access_ok(&vsock->dev)) {
 805                 goto err;
 806         }
 807
 808         if ((features & (1ULL << VIRTIO_F_ACCESS_PLATFORM))) {
 809                 if (vhost_init_device_iotlb(&vsock->dev))
 810                         goto err;
 811         }
 812
 813         if (features & (1ULL << VIRTIO_VSOCK_F_SEQPACKET))
 814                 vsock->seqpacket_allow = true;
 815
 816         for (i = 0; i < ARRAY_SIZE(vsock->vqs); i++) {
 817                 vq = &vsock->vqs[i];
 818                 mutex_lock(&vq->mutex);
 819                 vq->acked_features = features;
 820                 mutex_unlock(&vq->mutex);
 821         }
 822         mutex_unlock(&vsock->dev.mutex);
 823         return 0;
 824
 825 err:
 826         mutex_unlock(&vsock->dev.mutex);
 827         return -EFAULT;
 828 }
 829
 830 static long vhost_vsock_dev_ioctl(struct file *f, unsigned int ioctl,
 831                                   unsigned long arg)
 832 {
 833         struct vhost_vsock *vsock = f->private_data;
 834         void __user *argp = (void __user *)arg;
 835         u64 guest_cid;
 836         u64 features;
 837         int start;
 838         int r;
 839
 840         switch (ioctl) {
 841         case VHOST_VSOCK_SET_GUEST_CID:
 842                 if (copy_from_user(&guest_cid, argp, sizeof(guest_cid)))
 843                         return -EFAULT;
 844                 return vhost_vsock_set_cid(vsock, guest_cid);
 845         case VHOST_VSOCK_SET_RUNNING:
 846                 if (copy_from_user(&start, argp, sizeof(start)))
 847                         return -EFAULT;
 848                 if (start)
 849                         return vhost_vsock_start(vsock);
 850                 else
 851                         return vhost_vsock_stop(vsock, true);
 852         case VHOST_GET_FEATURES:
 853                 features = VHOST_VSOCK_FEATURES;
 854                 if (copy_to_user(argp, &features, sizeof(features)))
 855                         return -EFAULT;
 856                 return 0;
 857         case VHOST_SET_FEATURES:
 858                 if (copy_from_user(&features, argp, sizeof(features)))
 859                         return -EFAULT;
 860                 return vhost_vsock_set_features(vsock, features);
 861         case VHOST_GET_BACKEND_FEATURES:
 862                 features = VHOST_VSOCK_BACKEND_FEATURES;
 863                 if (copy_to_user(argp, &features, sizeof(features)))
 864                         return -EFAULT;
 865                 return 0;
 866         case VHOST_SET_BACKEND_FEATURES:
 867                 if (copy_from_user(&features, argp, sizeof(features)))
 868                         return -EFAULT;
 869                 if (features & ~VHOST_VSOCK_BACKEND_FEATURES)
 870                         return -EOPNOTSUPP;
 871                 vhost_set_backend_features(&vsock->dev, features);
 872                 return 0;
 873         default:
 874                 mutex_lock(&vsock->dev.mutex);
 875                 r = vhost_dev_ioctl(&vsock->dev, ioctl, argp);
 876                 if (r == -ENOIOCTLCMD)
 877                         r = vhost_vring_ioctl(&vsock->dev, ioctl, argp);
 878                 else
 879                         vhost_vsock_flush(vsock);
 880                 mutex_unlock(&vsock->dev.mutex);
 881                 return r;
 882         }
 883 }
 884
 885 static ssize_t vhost_vsock_chr_read_iter(struct kiocb *iocb, struct iov_iter *to)
 886 {
 887         struct file *file = iocb->ki_filp;
 888         struct vhost_vsock *vsock = file->private_data;
 889         struct vhost_dev *dev = &vsock->dev;
 890         int noblock = file->f_flags & O_NONBLOCK;
 891
 892         return vhost_chr_read_iter(dev, to, noblock);
 893 }
 894
 895 static ssize_t vhost_vsock_chr_write_iter(struct kiocb *iocb,
 896                                         struct iov_iter *from)
 897 {
 898         struct file *file = iocb->ki_filp;
 899         struct vhost_vsock *vsock = file->private_data;
 900         struct vhost_dev *dev = &vsock->dev;
 901
 902         return vhost_chr_write_iter(dev, from);
 903 }
 904
 905 static __poll_t vhost_vsock_chr_poll(struct file *file, poll_table *wait)
 906 {
 907         struct vhost_vsock *vsock = file->private_data;
 908         struct vhost_dev *dev = &vsock->dev;
 909
 910         return vhost_chr_poll(file, dev, wait);
 911 }
 912
 913 static const struct file_operations vhost_vsock_fops = {
 914         .owner          = THIS_MODULE,
 915         .open           = vhost_vsock_dev_open,
 916         .release        = vhost_vsock_dev_release,
 917         .llseek         = noop_llseek,
 918         .unlocked_ioctl = vhost_vsock_dev_ioctl,
 919         .compat_ioctl   = compat_ptr_ioctl,
 920         .read_iter      = vhost_vsock_chr_read_iter,
 921         .write_iter     = vhost_vsock_chr_write_iter,
 922         .poll           = vhost_vsock_chr_poll,
 923 };
 924
 925 static struct miscdevice vhost_vsock_misc = {
 926         .minor = VHOST_VSOCK_MINOR,
 927         .name = "vhost-vsock",
 928         .fops = &vhost_vsock_fops,
 929 };
 930
 931 static int __init vhost_vsock_init(void)
 932 {
 933         int ret;
 934
 935         ret = vsock_core_register(&vhost_transport.transport,
 936                                   VSOCK_TRANSPORT_F_H2G);
 937         if (ret < 0)
 938                 return ret;
 939
 940         ret = misc_register(&vhost_vsock_misc);
 941         if (ret) {
 942                 vsock_core_unregister(&vhost_transport.transport);
 943                 return ret;
 944         }
 945
 946         return 0;
 947 };
 948
 949 static void __exit vhost_vsock_exit(void)
 950 {
 951         misc_deregister(&vhost_vsock_misc);
 952         vsock_core_unregister(&vhost_transport.transport);
 953 };
 954
 955 module_init(vhost_vsock_init);
 956 module_exit(vhost_vsock_exit);
 957 MODULE_LICENSE("GPL v2");
 958 MODULE_AUTHOR("Asias He");
 959 MODULE_DESCRIPTION("vhost transport for vsock ");
 960 MODULE_ALIAS_MISCDEV(VHOST_VSOCK_MINOR);
 961 MODULE_ALIAS("devname:vhost-vsock");