drivers/xen/pvcalls-back.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * (c) 2017 Stefano Stabellini <stefano@aporeto.com>
   4  */
   5
   6 #include <linux/inet.h>
   7 #include <linux/kthread.h>
   8 #include <linux/list.h>
   9 #include <linux/radix-tree.h>
  10 #include <linux/module.h>
  11 #include <linux/semaphore.h>
  12 #include <linux/wait.h>
  13 #include <net/sock.h>
  14 #include <net/inet_common.h>
  15 #include <net/inet_connection_sock.h>
  16 #include <net/request_sock.h>
  17 #include <trace/events/sock.h>
  18
  19 #include <xen/events.h>
  20 #include <xen/grant_table.h>
  21 #include <xen/xen.h>
  22 #include <xen/xenbus.h>
  23 #include <xen/interface/io/pvcalls.h>
  24
  25 #define PVCALLS_VERSIONS "1"
  26 #define MAX_RING_ORDER XENBUS_MAX_RING_GRANT_ORDER
  27
  28 static struct pvcalls_back_global {
  29         struct list_head frontends;
  30         struct semaphore frontends_lock;
  31 } pvcalls_back_global;
  32
  33 /*
  34  * Per-frontend data structure. It contains pointers to the command
  35  * ring, its event channel, a list of active sockets and a tree of
  36  * passive sockets.
  37  */
  38 struct pvcalls_fedata {
  39         struct list_head list;
  40         struct xenbus_device *dev;
  41         struct xen_pvcalls_sring *sring;
  42         struct xen_pvcalls_back_ring ring;
  43         int irq;
  44         struct list_head socket_mappings;
  45         struct radix_tree_root socketpass_mappings;
  46         struct semaphore socket_lock;
  47 };
  48
  49 struct pvcalls_ioworker {
  50         struct work_struct register_work;
  51         struct workqueue_struct *wq;
  52 };
  53
  54 struct sock_mapping {
  55         struct list_head list;
  56         struct pvcalls_fedata *fedata;
  57         struct sockpass_mapping *sockpass;
  58         struct socket *sock;
  59         uint64_t id;
  60         grant_ref_t ref;
  61         struct pvcalls_data_intf *ring;
  62         void *bytes;
  63         struct pvcalls_data data;
  64         uint32_t ring_order;
  65         int irq;
  66         atomic_t read;
  67         atomic_t write;
  68         atomic_t io;
  69         atomic_t release;
  70         atomic_t eoi;
  71         void (*saved_data_ready)(struct sock *sk);
  72         struct pvcalls_ioworker ioworker;
  73 };
  74
  75 struct sockpass_mapping {
  76         struct list_head list;
  77         struct pvcalls_fedata *fedata;
  78         struct socket *sock;
  79         uint64_t id;
  80         struct xen_pvcalls_request reqcopy;
  81         spinlock_t copy_lock;
  82         struct workqueue_struct *wq;
  83         struct work_struct register_work;
  84         void (*saved_data_ready)(struct sock *sk);
  85 };
  86
  87 static irqreturn_t pvcalls_back_conn_event(int irq, void *sock_map);
  88 static int pvcalls_back_release_active(struct xenbus_device *dev,
  89                                        struct pvcalls_fedata *fedata,
  90                                        struct sock_mapping *map);
  91
  92 static bool pvcalls_conn_back_read(void *opaque)
  93 {
  94         struct sock_mapping *map = (struct sock_mapping *)opaque;
  95         struct msghdr msg;
  96         struct kvec vec[2];
  97         RING_IDX cons, prod, size, wanted, array_size, masked_prod, masked_cons;
  98         int32_t error;
  99         struct pvcalls_data_intf *intf = map->ring;
 100         struct pvcalls_data *data = &map->data;
 101         unsigned long flags;
 102         int ret;
 103
 104         array_size = XEN_FLEX_RING_SIZE(map->ring_order);
 105         cons = intf->in_cons;
 106         prod = intf->in_prod;
 107         error = intf->in_error;
 108         /* read the indexes first, then deal with the data */
 109         virt_mb();
 110
 111         if (error)
 112                 return false;
 113
 114         size = pvcalls_queued(prod, cons, array_size);
 115         if (size >= array_size)
 116                 return false;
 117         spin_lock_irqsave(&map->sock->sk->sk_receive_queue.lock, flags);
 118         if (skb_queue_empty(&map->sock->sk->sk_receive_queue)) {
 119                 atomic_set(&map->read, 0);
 120                 spin_unlock_irqrestore(&map->sock->sk->sk_receive_queue.lock,
 121                                 flags);
 122                 return true;
 123         }
 124         spin_unlock_irqrestore(&map->sock->sk->sk_receive_queue.lock, flags);
 125         wanted = array_size - size;
 126         masked_prod = pvcalls_mask(prod, array_size);
 127         masked_cons = pvcalls_mask(cons, array_size);
 128
 129         memset(&msg, 0, sizeof(msg));
 130         if (masked_prod < masked_cons) {
 131                 vec[0].iov_base = data->in + masked_prod;
 132                 vec[0].iov_len = wanted;
 133                 iov_iter_kvec(&msg.msg_iter, ITER_DEST, vec, 1, wanted);
 134         } else {
 135                 vec[0].iov_base = data->in + masked_prod;
 136                 vec[0].iov_len = array_size - masked_prod;
 137                 vec[1].iov_base = data->in;
 138                 vec[1].iov_len = wanted - vec[0].iov_len;
 139                 iov_iter_kvec(&msg.msg_iter, ITER_DEST, vec, 2, wanted);
 140         }
 141
 142         atomic_set(&map->read, 0);
 143         ret = inet_recvmsg(map->sock, &msg, wanted, MSG_DONTWAIT);
 144         WARN_ON(ret > wanted);
 145         if (ret == -EAGAIN) /* shouldn't happen */
 146                 return true;
 147         if (!ret)
 148                 ret = -ENOTCONN;
 149         spin_lock_irqsave(&map->sock->sk->sk_receive_queue.lock, flags);
 150         if (ret > 0 && !skb_queue_empty(&map->sock->sk->sk_receive_queue))
 151                 atomic_inc(&map->read);
 152         spin_unlock_irqrestore(&map->sock->sk->sk_receive_queue.lock, flags);
 153
 154         /* write the data, then modify the indexes */
 155         virt_wmb();
 156         if (ret < 0) {
 157                 atomic_set(&map->read, 0);
 158                 intf->in_error = ret;
 159         } else
 160                 intf->in_prod = prod + ret;
 161         /* update the indexes, then notify the other end */
 162         virt_wmb();
 163         notify_remote_via_irq(map->irq);
 164
 165         return true;
 166 }
 167
 168 static bool pvcalls_conn_back_write(struct sock_mapping *map)
 169 {
 170         struct pvcalls_data_intf *intf = map->ring;
 171         struct pvcalls_data *data = &map->data;
 172         struct msghdr msg;
 173         struct kvec vec[2];
 174         RING_IDX cons, prod, size, array_size;
 175         int ret;
 176
 177         atomic_set(&map->write, 0);
 178
 179         cons = intf->out_cons;
 180         prod = intf->out_prod;
 181         /* read the indexes before dealing with the data */
 182         virt_mb();
 183
 184         array_size = XEN_FLEX_RING_SIZE(map->ring_order);
 185         size = pvcalls_queued(prod, cons, array_size);
 186         if (size == 0)
 187                 return false;
 188
 189         memset(&msg, 0, sizeof(msg));
 190         msg.msg_flags |= MSG_DONTWAIT;
 191         if (pvcalls_mask(prod, array_size) > pvcalls_mask(cons, array_size)) {
 192                 vec[0].iov_base = data->out + pvcalls_mask(cons, array_size);
 193                 vec[0].iov_len = size;
 194                 iov_iter_kvec(&msg.msg_iter, ITER_SOURCE, vec, 1, size);
 195         } else {
 196                 vec[0].iov_base = data->out + pvcalls_mask(cons, array_size);
 197                 vec[0].iov_len = array_size - pvcalls_mask(cons, array_size);
 198                 vec[1].iov_base = data->out;
 199                 vec[1].iov_len = size - vec[0].iov_len;
 200                 iov_iter_kvec(&msg.msg_iter, ITER_SOURCE, vec, 2, size);
 201         }
 202
 203         ret = inet_sendmsg(map->sock, &msg, size);
 204         if (ret == -EAGAIN) {
 205                 atomic_inc(&map->write);
 206                 atomic_inc(&map->io);
 207                 return true;
 208         }
 209
 210         /* write the data, then update the indexes */
 211         virt_wmb();
 212         if (ret < 0) {
 213                 intf->out_error = ret;
 214         } else {
 215                 intf->out_error = 0;
 216                 intf->out_cons = cons + ret;
 217                 prod = intf->out_prod;
 218         }
 219         /* update the indexes, then notify the other end */
 220         virt_wmb();
 221         if (prod != cons + ret) {
 222                 atomic_inc(&map->write);
 223                 atomic_inc(&map->io);
 224         }
 225         notify_remote_via_irq(map->irq);
 226
 227         return true;
 228 }
 229
 230 static void pvcalls_back_ioworker(struct work_struct *work)
 231 {
 232         struct pvcalls_ioworker *ioworker = container_of(work,
 233                 struct pvcalls_ioworker, register_work);
 234         struct sock_mapping *map = container_of(ioworker, struct sock_mapping,
 235                 ioworker);
 236         unsigned int eoi_flags = XEN_EOI_FLAG_SPURIOUS;
 237
 238         while (atomic_read(&map->io) > 0) {
 239                 if (atomic_read(&map->release) > 0) {
 240                         atomic_set(&map->release, 0);
 241                         return;
 242                 }
 243
 244                 if (atomic_read(&map->read) > 0 &&
 245                     pvcalls_conn_back_read(map))
 246                         eoi_flags = 0;
 247                 if (atomic_read(&map->write) > 0 &&
 248                     pvcalls_conn_back_write(map))
 249                         eoi_flags = 0;
 250
 251                 if (atomic_read(&map->eoi) > 0 && !atomic_read(&map->write)) {
 252                         atomic_set(&map->eoi, 0);
 253                         xen_irq_lateeoi(map->irq, eoi_flags);
 254                         eoi_flags = XEN_EOI_FLAG_SPURIOUS;
 255                 }
 256
 257                 atomic_dec(&map->io);
 258         }
 259 }
 260
 261 static int pvcalls_back_socket(struct xenbus_device *dev,
 262                 struct xen_pvcalls_request *req)
 263 {
 264         struct pvcalls_fedata *fedata;
 265         int ret;
 266         struct xen_pvcalls_response *rsp;
 267
 268         fedata = dev_get_drvdata(&dev->dev);
 269
 270         if (req->u.socket.domain != AF_INET ||
 271             req->u.socket.type != SOCK_STREAM ||
 272             (req->u.socket.protocol != IPPROTO_IP &&
 273              req->u.socket.protocol != AF_INET))
 274                 ret = -EAFNOSUPPORT;
 275         else
 276                 ret = 0;
 277
 278         /* leave the actual socket allocation for later */
 279
 280         rsp = RING_GET_RESPONSE(&fedata->ring, fedata->ring.rsp_prod_pvt++);
 281         rsp->req_id = req->req_id;
 282         rsp->cmd = req->cmd;
 283         rsp->u.socket.id = req->u.socket.id;
 284         rsp->ret = ret;
 285
 286         return 0;
 287 }
 288
 289 static void pvcalls_sk_state_change(struct sock *sock)
 290 {
 291         struct sock_mapping *map = sock->sk_user_data;
 292
 293         if (map == NULL)
 294                 return;
 295
 296         atomic_inc(&map->read);
 297         notify_remote_via_irq(map->irq);
 298 }
 299
 300 static void pvcalls_sk_data_ready(struct sock *sock)
 301 {
 302         struct sock_mapping *map = sock->sk_user_data;
 303         struct pvcalls_ioworker *iow;
 304
 305         trace_sk_data_ready(sock);
 306
 307         if (map == NULL)
 308                 return;
 309
 310         iow = &map->ioworker;
 311         atomic_inc(&map->read);
 312         atomic_inc(&map->io);
 313         queue_work(iow->wq, &iow->register_work);
 314 }
 315
 316 static struct sock_mapping *pvcalls_new_active_socket(
 317                 struct pvcalls_fedata *fedata,
 318                 uint64_t id,
 319                 grant_ref_t ref,
 320                 evtchn_port_t evtchn,
 321                 struct socket *sock)
 322 {
 323         int ret;
 324         struct sock_mapping *map;
 325         void *page;
 326
 327         map = kzalloc(sizeof(*map), GFP_KERNEL);
 328         if (map == NULL) {
 329                 sock_release(sock);
 330                 return NULL;
 331         }
 332
 333         map->fedata = fedata;
 334         map->sock = sock;
 335         map->id = id;
 336         map->ref = ref;
 337
 338         ret = xenbus_map_ring_valloc(fedata->dev, &ref, 1, &page);
 339         if (ret < 0)
 340                 goto out;
 341         map->ring = page;
 342         map->ring_order = map->ring->ring_order;
 343         /* first read the order, then map the data ring */
 344         virt_rmb();
 345         if (map->ring_order > MAX_RING_ORDER) {
 346                 pr_warn("%s frontend requested ring_order %u, which is > MAX (%u)\n",
 347                                 __func__, map->ring_order, MAX_RING_ORDER);
 348                 goto out;
 349         }
 350         ret = xenbus_map_ring_valloc(fedata->dev, map->ring->ref,
 351                                      (1 << map->ring_order), &page);
 352         if (ret < 0)
 353                 goto out;
 354         map->bytes = page;
 355
 356         ret = bind_interdomain_evtchn_to_irqhandler_lateeoi(
 357                         fedata->dev, evtchn,
 358                         pvcalls_back_conn_event, 0, "pvcalls-backend", map);
 359         if (ret < 0)
 360                 goto out;
 361         map->irq = ret;
 362
 363         map->data.in = map->bytes;
 364         map->data.out = map->bytes + XEN_FLEX_RING_SIZE(map->ring_order);
 365
 366         map->ioworker.wq = alloc_ordered_workqueue("pvcalls_io", 0);
 367         if (!map->ioworker.wq)
 368                 goto out;
 369         atomic_set(&map->io, 1);
 370         INIT_WORK(&map->ioworker.register_work, pvcalls_back_ioworker);
 371
 372         down(&fedata->socket_lock);
 373         list_add_tail(&map->list, &fedata->socket_mappings);
 374         up(&fedata->socket_lock);
 375
 376         write_lock_bh(&map->sock->sk->sk_callback_lock);
 377         map->saved_data_ready = map->sock->sk->sk_data_ready;
 378         map->sock->sk->sk_user_data = map;
 379         map->sock->sk->sk_data_ready = pvcalls_sk_data_ready;
 380         map->sock->sk->sk_state_change = pvcalls_sk_state_change;
 381         write_unlock_bh(&map->sock->sk->sk_callback_lock);
 382
 383         return map;
 384 out:
 385         down(&fedata->socket_lock);
 386         list_del(&map->list);
 387         pvcalls_back_release_active(fedata->dev, fedata, map);
 388         up(&fedata->socket_lock);
 389         return NULL;
 390 }
 391
 392 static int pvcalls_back_connect(struct xenbus_device *dev,
 393                                 struct xen_pvcalls_request *req)
 394 {
 395         struct pvcalls_fedata *fedata;
 396         int ret = -EINVAL;
 397         struct socket *sock;
 398         struct sock_mapping *map;
 399         struct xen_pvcalls_response *rsp;
 400         struct sockaddr *sa = (struct sockaddr *)&req->u.connect.addr;
 401
 402         fedata = dev_get_drvdata(&dev->dev);
 403
 404         if (req->u.connect.len < sizeof(sa->sa_family) ||
 405             req->u.connect.len > sizeof(req->u.connect.addr) ||
 406             sa->sa_family != AF_INET)
 407                 goto out;
 408
 409         ret = sock_create(AF_INET, SOCK_STREAM, 0, &sock);
 410         if (ret < 0)
 411                 goto out;
 412         ret = inet_stream_connect(sock, sa, req->u.connect.len, 0);
 413         if (ret < 0) {
 414                 sock_release(sock);
 415                 goto out;
 416         }
 417
 418         map = pvcalls_new_active_socket(fedata,
 419                                         req->u.connect.id,
 420                                         req->u.connect.ref,
 421                                         req->u.connect.evtchn,
 422                                         sock);
 423         if (!map)
 424                 ret = -EFAULT;
 425
 426 out:
 427         rsp = RING_GET_RESPONSE(&fedata->ring, fedata->ring.rsp_prod_pvt++);
 428         rsp->req_id = req->req_id;
 429         rsp->cmd = req->cmd;
 430         rsp->u.connect.id = req->u.connect.id;
 431         rsp->ret = ret;
 432
 433         return 0;
 434 }
 435
 436 static int pvcalls_back_release_active(struct xenbus_device *dev,
 437                                        struct pvcalls_fedata *fedata,
 438                                        struct sock_mapping *map)
 439 {
 440         disable_irq(map->irq);
 441         if (map->sock->sk != NULL) {
 442                 write_lock_bh(&map->sock->sk->sk_callback_lock);
 443                 map->sock->sk->sk_user_data = NULL;
 444                 map->sock->sk->sk_data_ready = map->saved_data_ready;
 445                 write_unlock_bh(&map->sock->sk->sk_callback_lock);
 446         }
 447
 448         atomic_set(&map->release, 1);
 449         flush_work(&map->ioworker.register_work);
 450
 451         xenbus_unmap_ring_vfree(dev, map->bytes);
 452         xenbus_unmap_ring_vfree(dev, (void *)map->ring);
 453         unbind_from_irqhandler(map->irq, map);
 454
 455         sock_release(map->sock);
 456         kfree(map);
 457
 458         return 0;
 459 }
 460
 461 static int pvcalls_back_release_passive(struct xenbus_device *dev,
 462                                         struct pvcalls_fedata *fedata,
 463                                         struct sockpass_mapping *mappass)
 464 {
 465         if (mappass->sock->sk != NULL) {
 466                 write_lock_bh(&mappass->sock->sk->sk_callback_lock);
 467                 mappass->sock->sk->sk_user_data = NULL;
 468                 mappass->sock->sk->sk_data_ready = mappass->saved_data_ready;
 469                 write_unlock_bh(&mappass->sock->sk->sk_callback_lock);
 470         }
 471         sock_release(mappass->sock);
 472         destroy_workqueue(mappass->wq);
 473         kfree(mappass);
 474
 475         return 0;
 476 }
 477
 478 static int pvcalls_back_release(struct xenbus_device *dev,
 479                                 struct xen_pvcalls_request *req)
 480 {
 481         struct pvcalls_fedata *fedata;
 482         struct sock_mapping *map, *n;
 483         struct sockpass_mapping *mappass;
 484         int ret = 0;
 485         struct xen_pvcalls_response *rsp;
 486
 487         fedata = dev_get_drvdata(&dev->dev);
 488
 489         down(&fedata->socket_lock);
 490         list_for_each_entry_safe(map, n, &fedata->socket_mappings, list) {
 491                 if (map->id == req->u.release.id) {
 492                         list_del(&map->list);
 493                         up(&fedata->socket_lock);
 494                         ret = pvcalls_back_release_active(dev, fedata, map);
 495                         goto out;
 496                 }
 497         }
 498         mappass = radix_tree_lookup(&fedata->socketpass_mappings,
 499                                     req->u.release.id);
 500         if (mappass != NULL) {
 501                 radix_tree_delete(&fedata->socketpass_mappings, mappass->id);
 502                 up(&fedata->socket_lock);
 503                 ret = pvcalls_back_release_passive(dev, fedata, mappass);
 504         } else
 505                 up(&fedata->socket_lock);
 506
 507 out:
 508         rsp = RING_GET_RESPONSE(&fedata->ring, fedata->ring.rsp_prod_pvt++);
 509         rsp->req_id = req->req_id;
 510         rsp->u.release.id = req->u.release.id;
 511         rsp->cmd = req->cmd;
 512         rsp->ret = ret;
 513         return 0;
 514 }
 515
 516 static void __pvcalls_back_accept(struct work_struct *work)
 517 {
 518         struct sockpass_mapping *mappass = container_of(
 519                 work, struct sockpass_mapping, register_work);
 520         struct sock_mapping *map;
 521         struct pvcalls_ioworker *iow;
 522         struct pvcalls_fedata *fedata;
 523         struct socket *sock;
 524         struct xen_pvcalls_response *rsp;
 525         struct xen_pvcalls_request *req;
 526         int notify;
 527         int ret = -EINVAL;
 528         unsigned long flags;
 529
 530         fedata = mappass->fedata;
 531         /*
 532          * __pvcalls_back_accept can race against pvcalls_back_accept.
 533          * We only need to check the value of "cmd" on read. It could be
 534          * done atomically, but to simplify the code on the write side, we
 535          * use a spinlock.
 536          */
 537         spin_lock_irqsave(&mappass->copy_lock, flags);
 538         req = &mappass->reqcopy;
 539         if (req->cmd != PVCALLS_ACCEPT) {
 540                 spin_unlock_irqrestore(&mappass->copy_lock, flags);
 541                 return;
 542         }
 543         spin_unlock_irqrestore(&mappass->copy_lock, flags);
 544
 545         sock = sock_alloc();
 546         if (sock == NULL)
 547                 goto out_error;
 548         sock->type = mappass->sock->type;
 549         sock->ops = mappass->sock->ops;
 550
 551         ret = inet_accept(mappass->sock, sock, O_NONBLOCK, true);
 552         if (ret == -EAGAIN) {
 553                 sock_release(sock);
 554                 return;
 555         }
 556
 557         map = pvcalls_new_active_socket(fedata,
 558                                         req->u.accept.id_new,
 559                                         req->u.accept.ref,
 560                                         req->u.accept.evtchn,
 561                                         sock);
 562         if (!map) {
 563                 ret = -EFAULT;
 564                 goto out_error;
 565         }
 566
 567         map->sockpass = mappass;
 568         iow = &map->ioworker;
 569         atomic_inc(&map->read);
 570         atomic_inc(&map->io);
 571         queue_work(iow->wq, &iow->register_work);
 572
 573 out_error:
 574         rsp = RING_GET_RESPONSE(&fedata->ring, fedata->ring.rsp_prod_pvt++);
 575         rsp->req_id = req->req_id;
 576         rsp->cmd = req->cmd;
 577         rsp->u.accept.id = req->u.accept.id;
 578         rsp->ret = ret;
 579         RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&fedata->ring, notify);
 580         if (notify)
 581                 notify_remote_via_irq(fedata->irq);
 582
 583         mappass->reqcopy.cmd = 0;
 584 }
 585
 586 static void pvcalls_pass_sk_data_ready(struct sock *sock)
 587 {
 588         struct sockpass_mapping *mappass = sock->sk_user_data;
 589         struct pvcalls_fedata *fedata;
 590         struct xen_pvcalls_response *rsp;
 591         unsigned long flags;
 592         int notify;
 593
 594         trace_sk_data_ready(sock);
 595
 596         if (mappass == NULL)
 597                 return;
 598
 599         fedata = mappass->fedata;
 600         spin_lock_irqsave(&mappass->copy_lock, flags);
 601         if (mappass->reqcopy.cmd == PVCALLS_POLL) {
 602                 rsp = RING_GET_RESPONSE(&fedata->ring,
 603                                         fedata->ring.rsp_prod_pvt++);
 604                 rsp->req_id = mappass->reqcopy.req_id;
 605                 rsp->u.poll.id = mappass->reqcopy.u.poll.id;
 606                 rsp->cmd = mappass->reqcopy.cmd;
 607                 rsp->ret = 0;
 608
 609                 mappass->reqcopy.cmd = 0;
 610                 spin_unlock_irqrestore(&mappass->copy_lock, flags);
 611
 612                 RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&fedata->ring, notify);
 613                 if (notify)
 614                         notify_remote_via_irq(mappass->fedata->irq);
 615         } else {
 616                 spin_unlock_irqrestore(&mappass->copy_lock, flags);
 617                 queue_work(mappass->wq, &mappass->register_work);
 618         }
 619 }
 620
 621 static int pvcalls_back_bind(struct xenbus_device *dev,
 622                              struct xen_pvcalls_request *req)
 623 {
 624         struct pvcalls_fedata *fedata;
 625         int ret;
 626         struct sockpass_mapping *map;
 627         struct xen_pvcalls_response *rsp;
 628
 629         fedata = dev_get_drvdata(&dev->dev);
 630
 631         map = kzalloc(sizeof(*map), GFP_KERNEL);
 632         if (map == NULL) {
 633                 ret = -ENOMEM;
 634                 goto out;
 635         }
 636
 637         INIT_WORK(&map->register_work, __pvcalls_back_accept);
 638         spin_lock_init(&map->copy_lock);
 639         map->wq = alloc_ordered_workqueue("pvcalls_wq", 0);
 640         if (!map->wq) {
 641                 ret = -ENOMEM;
 642                 goto out;
 643         }
 644
 645         ret = sock_create(AF_INET, SOCK_STREAM, 0, &map->sock);
 646         if (ret < 0)
 647                 goto out;
 648
 649         ret = inet_bind(map->sock, (struct sockaddr *)&req->u.bind.addr,
 650                         req->u.bind.len);
 651         if (ret < 0)
 652                 goto out;
 653
 654         map->fedata = fedata;
 655         map->id = req->u.bind.id;
 656
 657         down(&fedata->socket_lock);
 658         ret = radix_tree_insert(&fedata->socketpass_mappings, map->id,
 659                                 map);
 660         up(&fedata->socket_lock);
 661         if (ret)
 662                 goto out;
 663
 664         write_lock_bh(&map->sock->sk->sk_callback_lock);
 665         map->saved_data_ready = map->sock->sk->sk_data_ready;
 666         map->sock->sk->sk_user_data = map;
 667         map->sock->sk->sk_data_ready = pvcalls_pass_sk_data_ready;
 668         write_unlock_bh(&map->sock->sk->sk_callback_lock);
 669
 670 out:
 671         if (ret) {
 672                 if (map && map->sock)
 673                         sock_release(map->sock);
 674                 if (map && map->wq)
 675                         destroy_workqueue(map->wq);
 676                 kfree(map);
 677         }
 678         rsp = RING_GET_RESPONSE(&fedata->ring, fedata->ring.rsp_prod_pvt++);
 679         rsp->req_id = req->req_id;
 680         rsp->cmd = req->cmd;
 681         rsp->u.bind.id = req->u.bind.id;
 682         rsp->ret = ret;
 683         return 0;
 684 }
 685
 686 static int pvcalls_back_listen(struct xenbus_device *dev,
 687                                struct xen_pvcalls_request *req)
 688 {
 689         struct pvcalls_fedata *fedata;
 690         int ret = -EINVAL;
 691         struct sockpass_mapping *map;
 692         struct xen_pvcalls_response *rsp;
 693
 694         fedata = dev_get_drvdata(&dev->dev);
 695
 696         down(&fedata->socket_lock);
 697         map = radix_tree_lookup(&fedata->socketpass_mappings, req->u.listen.id);
 698         up(&fedata->socket_lock);
 699         if (map == NULL)
 700                 goto out;
 701
 702         ret = inet_listen(map->sock, req->u.listen.backlog);
 703
 704 out:
 705         rsp = RING_GET_RESPONSE(&fedata->ring, fedata->ring.rsp_prod_pvt++);
 706         rsp->req_id = req->req_id;
 707         rsp->cmd = req->cmd;
 708         rsp->u.listen.id = req->u.listen.id;
 709         rsp->ret = ret;
 710         return 0;
 711 }
 712
 713 static int pvcalls_back_accept(struct xenbus_device *dev,
 714                                struct xen_pvcalls_request *req)
 715 {
 716         struct pvcalls_fedata *fedata;
 717         struct sockpass_mapping *mappass;
 718         int ret = -EINVAL;
 719         struct xen_pvcalls_response *rsp;
 720         unsigned long flags;
 721
 722         fedata = dev_get_drvdata(&dev->dev);
 723
 724         down(&fedata->socket_lock);
 725         mappass = radix_tree_lookup(&fedata->socketpass_mappings,
 726                 req->u.accept.id);
 727         up(&fedata->socket_lock);
 728         if (mappass == NULL)
 729                 goto out_error;
 730
 731         /*
 732          * Limitation of the current implementation: only support one
 733          * concurrent accept or poll call on one socket.
 734          */
 735         spin_lock_irqsave(&mappass->copy_lock, flags);
 736         if (mappass->reqcopy.cmd != 0) {
 737                 spin_unlock_irqrestore(&mappass->copy_lock, flags);
 738                 ret = -EINTR;
 739                 goto out_error;
 740         }
 741
 742         mappass->reqcopy = *req;
 743         spin_unlock_irqrestore(&mappass->copy_lock, flags);
 744         queue_work(mappass->wq, &mappass->register_work);
 745
 746         /* Tell the caller we don't need to send back a notification yet */
 747         return -1;
 748
 749 out_error:
 750         rsp = RING_GET_RESPONSE(&fedata->ring, fedata->ring.rsp_prod_pvt++);
 751         rsp->req_id = req->req_id;
 752         rsp->cmd = req->cmd;
 753         rsp->u.accept.id = req->u.accept.id;
 754         rsp->ret = ret;
 755         return 0;
 756 }
 757
 758 static int pvcalls_back_poll(struct xenbus_device *dev,
 759                              struct xen_pvcalls_request *req)
 760 {
 761         struct pvcalls_fedata *fedata;
 762         struct sockpass_mapping *mappass;
 763         struct xen_pvcalls_response *rsp;
 764         struct inet_connection_sock *icsk;
 765         struct request_sock_queue *queue;
 766         unsigned long flags;
 767         int ret;
 768         bool data;
 769
 770         fedata = dev_get_drvdata(&dev->dev);
 771
 772         down(&fedata->socket_lock);
 773         mappass = radix_tree_lookup(&fedata->socketpass_mappings,
 774                                     req->u.poll.id);
 775         up(&fedata->socket_lock);
 776         if (mappass == NULL)
 777                 return -EINVAL;
 778
 779         /*
 780          * Limitation of the current implementation: only support one
 781          * concurrent accept or poll call on one socket.
 782          */
 783         spin_lock_irqsave(&mappass->copy_lock, flags);
 784         if (mappass->reqcopy.cmd != 0) {
 785                 ret = -EINTR;
 786                 goto out;
 787         }
 788
 789         mappass->reqcopy = *req;
 790         icsk = inet_csk(mappass->sock->sk);
 791         queue = &icsk->icsk_accept_queue;
 792         data = READ_ONCE(queue->rskq_accept_head) != NULL;
 793         if (data) {
 794                 mappass->reqcopy.cmd = 0;
 795                 ret = 0;
 796                 goto out;
 797         }
 798         spin_unlock_irqrestore(&mappass->copy_lock, flags);
 799
 800         /* Tell the caller we don't need to send back a notification yet */
 801         return -1;
 802
 803 out:
 804         spin_unlock_irqrestore(&mappass->copy_lock, flags);
 805
 806         rsp = RING_GET_RESPONSE(&fedata->ring, fedata->ring.rsp_prod_pvt++);
 807         rsp->req_id = req->req_id;
 808         rsp->cmd = req->cmd;
 809         rsp->u.poll.id = req->u.poll.id;
 810         rsp->ret = ret;
 811         return 0;
 812 }
 813
 814 static int pvcalls_back_handle_cmd(struct xenbus_device *dev,
 815                                    struct xen_pvcalls_request *req)
 816 {
 817         int ret = 0;
 818
 819         switch (req->cmd) {
 820         case PVCALLS_SOCKET:
 821                 ret = pvcalls_back_socket(dev, req);
 822                 break;
 823         case PVCALLS_CONNECT:
 824                 ret = pvcalls_back_connect(dev, req);
 825                 break;
 826         case PVCALLS_RELEASE:
 827                 ret = pvcalls_back_release(dev, req);
 828                 break;
 829         case PVCALLS_BIND:
 830                 ret = pvcalls_back_bind(dev, req);
 831                 break;
 832         case PVCALLS_LISTEN:
 833                 ret = pvcalls_back_listen(dev, req);
 834                 break;
 835         case PVCALLS_ACCEPT:
 836                 ret = pvcalls_back_accept(dev, req);
 837                 break;
 838         case PVCALLS_POLL:
 839                 ret = pvcalls_back_poll(dev, req);
 840                 break;
 841         default:
 842         {
 843                 struct pvcalls_fedata *fedata;
 844                 struct xen_pvcalls_response *rsp;
 845
 846                 fedata = dev_get_drvdata(&dev->dev);
 847                 rsp = RING_GET_RESPONSE(
 848                                 &fedata->ring, fedata->ring.rsp_prod_pvt++);
 849                 rsp->req_id = req->req_id;
 850                 rsp->cmd = req->cmd;
 851                 rsp->ret = -ENOTSUPP;
 852                 break;
 853         }
 854         }
 855         return ret;
 856 }
 857
 858 static void pvcalls_back_work(struct pvcalls_fedata *fedata)
 859 {
 860         int notify, notify_all = 0, more = 1;
 861         struct xen_pvcalls_request req;
 862         struct xenbus_device *dev = fedata->dev;
 863
 864         while (more) {
 865                 while (RING_HAS_UNCONSUMED_REQUESTS(&fedata->ring)) {
 866                         RING_COPY_REQUEST(&fedata->ring,
 867                                           fedata->ring.req_cons++,
 868                                           &req);
 869
 870                         if (!pvcalls_back_handle_cmd(dev, &req)) {
 871                                 RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(
 872                                         &fedata->ring, notify);
 873                                 notify_all += notify;
 874                         }
 875                 }
 876
 877                 if (notify_all) {
 878                         notify_remote_via_irq(fedata->irq);
 879                         notify_all = 0;
 880                 }
 881
 882                 RING_FINAL_CHECK_FOR_REQUESTS(&fedata->ring, more);
 883         }
 884 }
 885
 886 static irqreturn_t pvcalls_back_event(int irq, void *dev_id)
 887 {
 888         struct xenbus_device *dev = dev_id;
 889         struct pvcalls_fedata *fedata = NULL;
 890         unsigned int eoi_flags = XEN_EOI_FLAG_SPURIOUS;
 891
 892         if (dev) {
 893                 fedata = dev_get_drvdata(&dev->dev);
 894                 if (fedata) {
 895                         pvcalls_back_work(fedata);
 896                         eoi_flags = 0;
 897                 }
 898         }
 899
 900         xen_irq_lateeoi(irq, eoi_flags);
 901
 902         return IRQ_HANDLED;
 903 }
 904
 905 static irqreturn_t pvcalls_back_conn_event(int irq, void *sock_map)
 906 {
 907         struct sock_mapping *map = sock_map;
 908         struct pvcalls_ioworker *iow;
 909
 910         if (map == NULL || map->sock == NULL || map->sock->sk == NULL ||
 911                 map->sock->sk->sk_user_data != map) {
 912                 xen_irq_lateeoi(irq, 0);
 913                 return IRQ_HANDLED;
 914         }
 915
 916         iow = &map->ioworker;
 917
 918         atomic_inc(&map->write);
 919         atomic_inc(&map->eoi);
 920         atomic_inc(&map->io);
 921         queue_work(iow->wq, &iow->register_work);
 922
 923         return IRQ_HANDLED;
 924 }
 925
 926 static int backend_connect(struct xenbus_device *dev)
 927 {
 928         int err;
 929         evtchn_port_t evtchn;
 930         grant_ref_t ring_ref;
 931         struct pvcalls_fedata *fedata = NULL;
 932
 933         fedata = kzalloc(sizeof(struct pvcalls_fedata), GFP_KERNEL);
 934         if (!fedata)
 935                 return -ENOMEM;
 936
 937         fedata->irq = -1;
 938         err = xenbus_scanf(XBT_NIL, dev->otherend, "port", "%u",
 939                            &evtchn);
 940         if (err != 1) {
 941                 err = -EINVAL;
 942                 xenbus_dev_fatal(dev, err, "reading %s/event-channel",
 943                                  dev->otherend);
 944                 goto error;
 945         }
 946
 947         err = xenbus_scanf(XBT_NIL, dev->otherend, "ring-ref", "%u", &ring_ref);
 948         if (err != 1) {
 949                 err = -EINVAL;
 950                 xenbus_dev_fatal(dev, err, "reading %s/ring-ref",
 951                                  dev->otherend);
 952                 goto error;
 953         }
 954
 955         err = bind_interdomain_evtchn_to_irq_lateeoi(dev, evtchn);
 956         if (err < 0)
 957                 goto error;
 958         fedata->irq = err;
 959
 960         err = request_threaded_irq(fedata->irq, NULL, pvcalls_back_event,
 961                                    IRQF_ONESHOT, "pvcalls-back", dev);
 962         if (err < 0)
 963                 goto error;
 964
 965         err = xenbus_map_ring_valloc(dev, &ring_ref, 1,
 966                                      (void **)&fedata->sring);
 967         if (err < 0)
 968                 goto error;
 969
 970         BACK_RING_INIT(&fedata->ring, fedata->sring, XEN_PAGE_SIZE * 1);
 971         fedata->dev = dev;
 972
 973         INIT_LIST_HEAD(&fedata->socket_mappings);
 974         INIT_RADIX_TREE(&fedata->socketpass_mappings, GFP_KERNEL);
 975         sema_init(&fedata->socket_lock, 1);
 976         dev_set_drvdata(&dev->dev, fedata);
 977
 978         down(&pvcalls_back_global.frontends_lock);
 979         list_add_tail(&fedata->list, &pvcalls_back_global.frontends);
 980         up(&pvcalls_back_global.frontends_lock);
 981
 982         return 0;
 983
 984  error:
 985         if (fedata->irq >= 0)
 986                 unbind_from_irqhandler(fedata->irq, dev);
 987         if (fedata->sring != NULL)
 988                 xenbus_unmap_ring_vfree(dev, fedata->sring);
 989         kfree(fedata);
 990         return err;
 991 }
 992
 993 static int backend_disconnect(struct xenbus_device *dev)
 994 {
 995         struct pvcalls_fedata *fedata;
 996         struct sock_mapping *map, *n;
 997         struct sockpass_mapping *mappass;
 998         struct radix_tree_iter iter;
 999         void **slot;
1000
1001
1002         fedata = dev_get_drvdata(&dev->dev);
1003
1004         down(&fedata->socket_lock);
1005         list_for_each_entry_safe(map, n, &fedata->socket_mappings, list) {
1006                 list_del(&map->list);
1007                 pvcalls_back_release_active(dev, fedata, map);
1008         }
1009
1010         radix_tree_for_each_slot(slot, &fedata->socketpass_mappings, &iter, 0) {
1011                 mappass = radix_tree_deref_slot(slot);
1012                 if (!mappass)
1013                         continue;
1014                 if (radix_tree_exception(mappass)) {
1015                         if (radix_tree_deref_retry(mappass))
1016                                 slot = radix_tree_iter_retry(&iter);
1017                 } else {
1018                         radix_tree_delete(&fedata->socketpass_mappings,
1019                                           mappass->id);
1020                         pvcalls_back_release_passive(dev, fedata, mappass);
1021                 }
1022         }
1023         up(&fedata->socket_lock);
1024
1025         unbind_from_irqhandler(fedata->irq, dev);
1026         xenbus_unmap_ring_vfree(dev, fedata->sring);
1027
1028         list_del(&fedata->list);
1029         kfree(fedata);
1030         dev_set_drvdata(&dev->dev, NULL);
1031
1032         return 0;
1033 }
1034
1035 static int pvcalls_back_probe(struct xenbus_device *dev,
1036                               const struct xenbus_device_id *id)
1037 {
1038         int err, abort;
1039         struct xenbus_transaction xbt;
1040
1041 again:
1042         abort = 1;
1043
1044         err = xenbus_transaction_start(&xbt);
1045         if (err) {
1046                 pr_warn("%s cannot create xenstore transaction\n", __func__);
1047                 return err;
1048         }
1049
1050         err = xenbus_printf(xbt, dev->nodename, "versions", "%s",
1051                             PVCALLS_VERSIONS);
1052         if (err) {
1053                 pr_warn("%s write out 'versions' failed\n", __func__);
1054                 goto abort;
1055         }
1056
1057         err = xenbus_printf(xbt, dev->nodename, "max-page-order", "%u",
1058                             MAX_RING_ORDER);
1059         if (err) {
1060                 pr_warn("%s write out 'max-page-order' failed\n", __func__);
1061                 goto abort;
1062         }
1063
1064         err = xenbus_printf(xbt, dev->nodename, "function-calls",
1065                             XENBUS_FUNCTIONS_CALLS);
1066         if (err) {
1067                 pr_warn("%s write out 'function-calls' failed\n", __func__);
1068                 goto abort;
1069         }
1070
1071         abort = 0;
1072 abort:
1073         err = xenbus_transaction_end(xbt, abort);
1074         if (err) {
1075                 if (err == -EAGAIN && !abort)
1076                         goto again;
1077                 pr_warn("%s cannot complete xenstore transaction\n", __func__);
1078                 return err;
1079         }
1080
1081         if (abort)
1082                 return -EFAULT;
1083
1084         xenbus_switch_state(dev, XenbusStateInitWait);
1085
1086         return 0;
1087 }
1088
1089 static void set_backend_state(struct xenbus_device *dev,
1090                               enum xenbus_state state)
1091 {
1092         while (dev->state != state) {
1093                 switch (dev->state) {
1094                 case XenbusStateClosed:
1095                         switch (state) {
1096                         case XenbusStateInitWait:
1097                         case XenbusStateConnected:
1098                                 xenbus_switch_state(dev, XenbusStateInitWait);
1099                                 break;
1100                         case XenbusStateClosing:
1101                                 xenbus_switch_state(dev, XenbusStateClosing);
1102                                 break;
1103                         default:
1104                                 WARN_ON(1);
1105                         }
1106                         break;
1107                 case XenbusStateInitWait:
1108                 case XenbusStateInitialised:
1109                         switch (state) {
1110                         case XenbusStateConnected:
1111                                 if (backend_connect(dev))
1112                                         return;
1113                                 xenbus_switch_state(dev, XenbusStateConnected);
1114                                 break;
1115                         case XenbusStateClosing:
1116                         case XenbusStateClosed:
1117                                 xenbus_switch_state(dev, XenbusStateClosing);
1118                                 break;
1119                         default:
1120                                 WARN_ON(1);
1121                         }
1122                         break;
1123                 case XenbusStateConnected:
1124                         switch (state) {
1125                         case XenbusStateInitWait:
1126                         case XenbusStateClosing:
1127                         case XenbusStateClosed:
1128                                 down(&pvcalls_back_global.frontends_lock);
1129                                 backend_disconnect(dev);
1130                                 up(&pvcalls_back_global.frontends_lock);
1131                                 xenbus_switch_state(dev, XenbusStateClosing);
1132                                 break;
1133                         default:
1134                                 WARN_ON(1);
1135                         }
1136                         break;
1137                 case XenbusStateClosing:
1138                         switch (state) {
1139                         case XenbusStateInitWait:
1140                         case XenbusStateConnected:
1141                         case XenbusStateClosed:
1142                                 xenbus_switch_state(dev, XenbusStateClosed);
1143                                 break;
1144                         default:
1145                                 WARN_ON(1);
1146                         }
1147                         break;
1148                 default:
1149                         WARN_ON(1);
1150                 }
1151         }
1152 }
1153
1154 static void pvcalls_back_changed(struct xenbus_device *dev,
1155                                  enum xenbus_state frontend_state)
1156 {
1157         switch (frontend_state) {
1158         case XenbusStateInitialising:
1159                 set_backend_state(dev, XenbusStateInitWait);
1160                 break;
1161
1162         case XenbusStateInitialised:
1163         case XenbusStateConnected:
1164                 set_backend_state(dev, XenbusStateConnected);
1165                 break;
1166
1167         case XenbusStateClosing:
1168                 set_backend_state(dev, XenbusStateClosing);
1169                 break;
1170
1171         case XenbusStateClosed:
1172                 set_backend_state(dev, XenbusStateClosed);
1173                 if (xenbus_dev_is_online(dev))
1174                         break;
1175                 device_unregister(&dev->dev);
1176                 break;
1177         case XenbusStateUnknown:
1178                 set_backend_state(dev, XenbusStateClosed);
1179                 device_unregister(&dev->dev);
1180                 break;
1181
1182         default:
1183                 xenbus_dev_fatal(dev, -EINVAL, "saw state %d at frontend",
1184                                  frontend_state);
1185                 break;
1186         }
1187 }
1188
1189 static void pvcalls_back_remove(struct xenbus_device *dev)
1190 {
1191 }
1192
1193 static int pvcalls_back_uevent(const struct xenbus_device *xdev,
1194                                struct kobj_uevent_env *env)
1195 {
1196         return 0;
1197 }
1198
1199 static const struct xenbus_device_id pvcalls_back_ids[] = {
1200         { "pvcalls" },
1201         { "" }
1202 };
1203
1204 static struct xenbus_driver pvcalls_back_driver = {
1205         .ids = pvcalls_back_ids,
1206         .probe = pvcalls_back_probe,
1207         .remove = pvcalls_back_remove,
1208         .uevent = pvcalls_back_uevent,
1209         .otherend_changed = pvcalls_back_changed,
1210 };
1211
1212 static int __init pvcalls_back_init(void)
1213 {
1214         int ret;
1215
1216         if (!xen_domain())
1217                 return -ENODEV;
1218
1219         ret = xenbus_register_backend(&pvcalls_back_driver);
1220         if (ret < 0)
1221                 return ret;
1222
1223         sema_init(&pvcalls_back_global.frontends_lock, 1);
1224         INIT_LIST_HEAD(&pvcalls_back_global.frontends);
1225         return 0;
1226 }
1227 module_init(pvcalls_back_init);
1228
1229 static void __exit pvcalls_back_fin(void)
1230 {
1231         struct pvcalls_fedata *fedata, *nfedata;
1232
1233         down(&pvcalls_back_global.frontends_lock);
1234         list_for_each_entry_safe(fedata, nfedata,
1235                                  &pvcalls_back_global.frontends, list) {
1236                 backend_disconnect(fedata->dev);
1237         }
1238         up(&pvcalls_back_global.frontends_lock);
1239
1240         xenbus_unregister_driver(&pvcalls_back_driver);
1241 }
1242
1243 module_exit(pvcalls_back_fin);
1244
1245 MODULE_DESCRIPTION("Xen PV Calls backend driver");
1246 MODULE_AUTHOR("Stefano Stabellini <sstabellini@kernel.org>");
1247 MODULE_LICENSE("GPL");