drivers/xen/pvcalls-back.c

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