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         atomic_t eoi;
  79         void (*saved_data_ready)(struct sock *sk);
  80         struct pvcalls_ioworker ioworker;
  81 };
  82
  83 struct sockpass_mapping {
  84         struct list_head list;
  85         struct pvcalls_fedata *fedata;
  86         struct socket *sock;
  87         uint64_t id;
  88         struct xen_pvcalls_request reqcopy;
  89         spinlock_t copy_lock;
  90         struct workqueue_struct *wq;
  91         struct work_struct register_work;
  92         void (*saved_data_ready)(struct sock *sk);
  93 };
  94
  95 static irqreturn_t pvcalls_back_conn_event(int irq, void *sock_map);
  96 static int pvcalls_back_release_active(struct xenbus_device *dev,
  97                                        struct pvcalls_fedata *fedata,
  98                                        struct sock_mapping *map);
  99
 100 static bool pvcalls_conn_back_read(void *opaque)
 101 {
 102         struct sock_mapping *map = (struct sock_mapping *)opaque;
 103         struct msghdr msg;
 104         struct kvec vec[2];
 105         RING_IDX cons, prod, size, wanted, array_size, masked_prod, masked_cons;
 106         int32_t error;
 107         struct pvcalls_data_intf *intf = map->ring;
 108         struct pvcalls_data *data = &map->data;
 109         unsigned long flags;
 110         int ret;
 111
 112         array_size = XEN_FLEX_RING_SIZE(map->ring_order);
 113         cons = intf->in_cons;
 114         prod = intf->in_prod;
 115         error = intf->in_error;
 116         /* read the indexes first, then deal with the data */
 117         virt_mb();
 118
 119         if (error)
 120                 return false;
 121
 122         size = pvcalls_queued(prod, cons, array_size);
 123         if (size >= array_size)
 124                 return false;
 125         spin_lock_irqsave(&map->sock->sk->sk_receive_queue.lock, flags);
 126         if (skb_queue_empty(&map->sock->sk->sk_receive_queue)) {
 127                 atomic_set(&map->read, 0);
 128                 spin_unlock_irqrestore(&map->sock->sk->sk_receive_queue.lock,
 129                                 flags);
 130                 return true;
 131         }
 132         spin_unlock_irqrestore(&map->sock->sk->sk_receive_queue.lock, flags);
 133         wanted = array_size - size;
 134         masked_prod = pvcalls_mask(prod, array_size);
 135         masked_cons = pvcalls_mask(cons, array_size);
 136
 137         memset(&msg, 0, sizeof(msg));
 138         if (masked_prod < masked_cons) {
 139                 vec[0].iov_base = data->in + masked_prod;
 140                 vec[0].iov_len = wanted;
 141                 iov_iter_kvec(&msg.msg_iter, ITER_KVEC|WRITE, vec, 1, wanted);
 142         } else {
 143                 vec[0].iov_base = data->in + masked_prod;
 144                 vec[0].iov_len = array_size - masked_prod;
 145                 vec[1].iov_base = data->in;
 146                 vec[1].iov_len = wanted - vec[0].iov_len;
 147                 iov_iter_kvec(&msg.msg_iter, ITER_KVEC|WRITE, vec, 2, wanted);
 148         }
 149
 150         atomic_set(&map->read, 0);
 151         ret = inet_recvmsg(map->sock, &msg, wanted, MSG_DONTWAIT);
 152         WARN_ON(ret > wanted);
 153         if (ret == -EAGAIN) /* shouldn't happen */
 154                 return true;
 155         if (!ret)
 156                 ret = -ENOTCONN;
 157         spin_lock_irqsave(&map->sock->sk->sk_receive_queue.lock, flags);
 158         if (ret > 0 && !skb_queue_empty(&map->sock->sk->sk_receive_queue))
 159                 atomic_inc(&map->read);
 160         spin_unlock_irqrestore(&map->sock->sk->sk_receive_queue.lock, flags);
 161
 162         /* write the data, then modify the indexes */
 163         virt_wmb();
 164         if (ret < 0) {
 165                 atomic_set(&map->read, 0);
 166                 intf->in_error = ret;
 167         } else
 168                 intf->in_prod = prod + ret;
 169         /* update the indexes, then notify the other end */
 170         virt_wmb();
 171         notify_remote_via_irq(map->irq);
 172
 173         return true;
 174 }
 175
 176 static bool pvcalls_conn_back_write(struct sock_mapping *map)
 177 {
 178         struct pvcalls_data_intf *intf = map->ring;
 179         struct pvcalls_data *data = &map->data;
 180         struct msghdr msg;
 181         struct kvec vec[2];
 182         RING_IDX cons, prod, size, array_size;
 183         int ret;
 184
 185         cons = intf->out_cons;
 186         prod = intf->out_prod;
 187         /* read the indexes before dealing with the data */
 188         virt_mb();
 189
 190         array_size = XEN_FLEX_RING_SIZE(map->ring_order);
 191         size = pvcalls_queued(prod, cons, array_size);
 192         if (size == 0)
 193                 return false;
 194
 195         memset(&msg, 0, sizeof(msg));
 196         msg.msg_flags |= MSG_DONTWAIT;
 197         if (pvcalls_mask(prod, array_size) > pvcalls_mask(cons, array_size)) {
 198                 vec[0].iov_base = data->out + pvcalls_mask(cons, array_size);
 199                 vec[0].iov_len = size;
 200                 iov_iter_kvec(&msg.msg_iter, ITER_KVEC|READ, vec, 1, size);
 201         } else {
 202                 vec[0].iov_base = data->out + pvcalls_mask(cons, array_size);
 203                 vec[0].iov_len = array_size - pvcalls_mask(cons, array_size);
 204                 vec[1].iov_base = data->out;
 205                 vec[1].iov_len = size - vec[0].iov_len;
 206                 iov_iter_kvec(&msg.msg_iter, ITER_KVEC|READ, vec, 2, size);
 207         }
 208
 209         atomic_set(&map->write, 0);
 210         ret = inet_sendmsg(map->sock, &msg, size);
 211         if (ret == -EAGAIN) {
 212                 atomic_inc(&map->write);
 213                 atomic_inc(&map->io);
 214                 return true;
 215         }
 216
 217         /* write the data, then update the indexes */
 218         virt_wmb();
 219         if (ret < 0) {
 220                 intf->out_error = ret;
 221         } else {
 222                 intf->out_error = 0;
 223                 intf->out_cons = cons + ret;
 224                 prod = intf->out_prod;
 225         }
 226         /* update the indexes, then notify the other end */
 227         virt_wmb();
 228         if (prod != cons + ret) {
 229                 atomic_inc(&map->write);
 230                 atomic_inc(&map->io);
 231         }
 232         notify_remote_via_irq(map->irq);
 233
 234         return true;
 235 }
 236
 237 static void pvcalls_back_ioworker(struct work_struct *work)
 238 {
 239         struct pvcalls_ioworker *ioworker = container_of(work,
 240                 struct pvcalls_ioworker, register_work);
 241         struct sock_mapping *map = container_of(ioworker, struct sock_mapping,
 242                 ioworker);
 243         unsigned int eoi_flags = XEN_EOI_FLAG_SPURIOUS;
 244
 245         while (atomic_read(&map->io) > 0) {
 246                 if (atomic_read(&map->release) > 0) {
 247                         atomic_set(&map->release, 0);
 248                         return;
 249                 }
 250
 251                 if (atomic_read(&map->read) > 0 &&
 252                     pvcalls_conn_back_read(map))
 253                         eoi_flags = 0;
 254                 if (atomic_read(&map->write) > 0 &&
 255                     pvcalls_conn_back_write(map))
 256                         eoi_flags = 0;
 257
 258                 if (atomic_read(&map->eoi) > 0 && !atomic_read(&map->write)) {
 259                         atomic_set(&map->eoi, 0);
 260                         xen_irq_lateeoi(map->irq, eoi_flags);
 261                         eoi_flags = XEN_EOI_FLAG_SPURIOUS;
 262                 }
 263
 264                 atomic_dec(&map->io);
 265         }
 266 }
 267
 268 static int pvcalls_back_socket(struct xenbus_device *dev,
 269                 struct xen_pvcalls_request *req)
 270 {
 271         struct pvcalls_fedata *fedata;
 272         int ret;
 273         struct xen_pvcalls_response *rsp;
 274
 275         fedata = dev_get_drvdata(&dev->dev);
 276
 277         if (req->u.socket.domain != AF_INET ||
 278             req->u.socket.type != SOCK_STREAM ||
 279             (req->u.socket.protocol != IPPROTO_IP &&
 280              req->u.socket.protocol != AF_INET))
 281                 ret = -EAFNOSUPPORT;
 282         else
 283                 ret = 0;
 284
 285         /* leave the actual socket allocation for later */
 286
 287         rsp = RING_GET_RESPONSE(&fedata->ring, fedata->ring.rsp_prod_pvt++);
 288         rsp->req_id = req->req_id;
 289         rsp->cmd = req->cmd;
 290         rsp->u.socket.id = req->u.socket.id;
 291         rsp->ret = ret;
 292
 293         return 0;
 294 }
 295
 296 static void pvcalls_sk_state_change(struct sock *sock)
 297 {
 298         struct sock_mapping *map = sock->sk_user_data;
 299
 300         if (map == NULL)
 301                 return;
 302
 303         atomic_inc(&map->read);
 304         notify_remote_via_irq(map->irq);
 305 }
 306
 307 static void pvcalls_sk_data_ready(struct sock *sock)
 308 {
 309         struct sock_mapping *map = sock->sk_user_data;
 310         struct pvcalls_ioworker *iow;
 311
 312         if (map == NULL)
 313                 return;
 314
 315         iow = &map->ioworker;
 316         atomic_inc(&map->read);
 317         atomic_inc(&map->io);
 318         queue_work(iow->wq, &iow->register_work);
 319 }
 320
 321 static struct sock_mapping *pvcalls_new_active_socket(
 322                 struct pvcalls_fedata *fedata,
 323                 uint64_t id,
 324                 grant_ref_t ref,
 325                 uint32_t evtchn,
 326                 struct socket *sock)
 327 {
 328         int ret;
 329         struct sock_mapping *map;
 330         void *page;
 331
 332         map = kzalloc(sizeof(*map), GFP_KERNEL);
 333         if (map == NULL) {
 334                 sock_release(sock);
 335                 return NULL;
 336         }
 337
 338         map->fedata = fedata;
 339         map->sock = sock;
 340         map->id = id;
 341         map->ref = ref;
 342
 343         ret = xenbus_map_ring_valloc(fedata->dev, &ref, 1, &page);
 344         if (ret < 0)
 345                 goto out;
 346         map->ring = page;
 347         map->ring_order = map->ring->ring_order;
 348         /* first read the order, then map the data ring */
 349         virt_rmb();
 350         if (map->ring_order > MAX_RING_ORDER) {
 351                 pr_warn("%s frontend requested ring_order %u, which is > MAX (%u)\n",
 352                                 __func__, map->ring_order, MAX_RING_ORDER);
 353                 goto out;
 354         }
 355         ret = xenbus_map_ring_valloc(fedata->dev, map->ring->ref,
 356                                      (1 << map->ring_order), &page);
 357         if (ret < 0)
 358                 goto out;
 359         map->bytes = page;
 360
 361         ret = bind_interdomain_evtchn_to_irqhandler_lateeoi(
 362                         fedata->dev->otherend_id, evtchn,
 363                         pvcalls_back_conn_event, 0, "pvcalls-backend", map);
 364         if (ret < 0)
 365                 goto out;
 366         map->irq = ret;
 367
 368         map->data.in = map->bytes;
 369         map->data.out = map->bytes + XEN_FLEX_RING_SIZE(map->ring_order);
 370
 371         map->ioworker.wq = alloc_workqueue("pvcalls_io", WQ_UNBOUND, 1);
 372         if (!map->ioworker.wq)
 373                 goto out;
 374         atomic_set(&map->io, 1);
 375         INIT_WORK(&map->ioworker.register_work, pvcalls_back_ioworker);
 376
 377         down(&fedata->socket_lock);
 378         list_add_tail(&map->list, &fedata->socket_mappings);
 379         up(&fedata->socket_lock);
 380
 381         write_lock_bh(&map->sock->sk->sk_callback_lock);
 382         map->saved_data_ready = map->sock->sk->sk_data_ready;
 383         map->sock->sk->sk_user_data = map;
 384         map->sock->sk->sk_data_ready = pvcalls_sk_data_ready;
 385         map->sock->sk->sk_state_change = pvcalls_sk_state_change;
 386         write_unlock_bh(&map->sock->sk->sk_callback_lock);
 387
 388         return map;
 389 out:
 390         down(&fedata->socket_lock);
 391         list_del(&map->list);
 392         pvcalls_back_release_active(fedata->dev, fedata, map);
 393         up(&fedata->socket_lock);
 394         return NULL;
 395 }
 396
 397 static int pvcalls_back_connect(struct xenbus_device *dev,
 398                                 struct xen_pvcalls_request *req)
 399 {
 400         struct pvcalls_fedata *fedata;
 401         int ret = -EINVAL;
 402         struct socket *sock;
 403         struct sock_mapping *map;
 404         struct xen_pvcalls_response *rsp;
 405         struct sockaddr *sa = (struct sockaddr *)&req->u.connect.addr;
 406
 407         fedata = dev_get_drvdata(&dev->dev);
 408
 409         if (req->u.connect.len < sizeof(sa->sa_family) ||
 410             req->u.connect.len > sizeof(req->u.connect.addr) ||
 411             sa->sa_family != AF_INET)
 412                 goto out;
 413
 414         ret = sock_create(AF_INET, SOCK_STREAM, 0, &sock);
 415         if (ret < 0)
 416                 goto out;
 417         ret = inet_stream_connect(sock, sa, req->u.connect.len, 0);
 418         if (ret < 0) {
 419                 sock_release(sock);
 420                 goto out;
 421         }
 422
 423         map = pvcalls_new_active_socket(fedata,
 424                                         req->u.connect.id,
 425                                         req->u.connect.ref,
 426                                         req->u.connect.evtchn,
 427                                         sock);
 428         if (!map)
 429                 ret = -EFAULT;
 430
 431 out:
 432         rsp = RING_GET_RESPONSE(&fedata->ring, fedata->ring.rsp_prod_pvt++);
 433         rsp->req_id = req->req_id;
 434         rsp->cmd = req->cmd;
 435         rsp->u.connect.id = req->u.connect.id;
 436         rsp->ret = ret;
 437
 438         return 0;
 439 }
 440
 441 static int pvcalls_back_release_active(struct xenbus_device *dev,
 442                                        struct pvcalls_fedata *fedata,
 443                                        struct sock_mapping *map)
 444 {
 445         disable_irq(map->irq);
 446         if (map->sock->sk != NULL) {
 447                 write_lock_bh(&map->sock->sk->sk_callback_lock);
 448                 map->sock->sk->sk_user_data = NULL;
 449                 map->sock->sk->sk_data_ready = map->saved_data_ready;
 450                 write_unlock_bh(&map->sock->sk->sk_callback_lock);
 451         }
 452
 453         atomic_set(&map->release, 1);
 454         flush_work(&map->ioworker.register_work);
 455
 456         xenbus_unmap_ring_vfree(dev, map->bytes);
 457         xenbus_unmap_ring_vfree(dev, (void *)map->ring);
 458         unbind_from_irqhandler(map->irq, map);
 459
 460         sock_release(map->sock);
 461         kfree(map);
 462
 463         return 0;
 464 }
 465
 466 static int pvcalls_back_release_passive(struct xenbus_device *dev,
 467                                         struct pvcalls_fedata *fedata,
 468                                         struct sockpass_mapping *mappass)
 469 {
 470         if (mappass->sock->sk != NULL) {
 471                 write_lock_bh(&mappass->sock->sk->sk_callback_lock);
 472                 mappass->sock->sk->sk_user_data = NULL;
 473                 mappass->sock->sk->sk_data_ready = mappass->saved_data_ready;
 474                 write_unlock_bh(&mappass->sock->sk->sk_callback_lock);
 475         }
 476         sock_release(mappass->sock);
 477         flush_workqueue(mappass->wq);
 478         destroy_workqueue(mappass->wq);
 479         kfree(mappass);
 480
 481         return 0;
 482 }
 483
 484 static int pvcalls_back_release(struct xenbus_device *dev,
 485                                 struct xen_pvcalls_request *req)
 486 {
 487         struct pvcalls_fedata *fedata;
 488         struct sock_mapping *map, *n;
 489         struct sockpass_mapping *mappass;
 490         int ret = 0;
 491         struct xen_pvcalls_response *rsp;
 492
 493         fedata = dev_get_drvdata(&dev->dev);
 494
 495         down(&fedata->socket_lock);
 496         list_for_each_entry_safe(map, n, &fedata->socket_mappings, list) {
 497                 if (map->id == req->u.release.id) {
 498                         list_del(&map->list);
 499                         up(&fedata->socket_lock);
 500                         ret = pvcalls_back_release_active(dev, fedata, map);
 501                         goto out;
 502                 }
 503         }
 504         mappass = radix_tree_lookup(&fedata->socketpass_mappings,
 505                                     req->u.release.id);
 506         if (mappass != NULL) {
 507                 radix_tree_delete(&fedata->socketpass_mappings, mappass->id);
 508                 up(&fedata->socket_lock);
 509                 ret = pvcalls_back_release_passive(dev, fedata, mappass);
 510         } else
 511                 up(&fedata->socket_lock);
 512
 513 out:
 514         rsp = RING_GET_RESPONSE(&fedata->ring, fedata->ring.rsp_prod_pvt++);
 515         rsp->req_id = req->req_id;
 516         rsp->u.release.id = req->u.release.id;
 517         rsp->cmd = req->cmd;
 518         rsp->ret = ret;
 519         return 0;
 520 }
 521
 522 static void __pvcalls_back_accept(struct work_struct *work)
 523 {
 524         struct sockpass_mapping *mappass = container_of(
 525                 work, struct sockpass_mapping, register_work);
 526         struct sock_mapping *map;
 527         struct pvcalls_ioworker *iow;
 528         struct pvcalls_fedata *fedata;
 529         struct socket *sock;
 530         struct xen_pvcalls_response *rsp;
 531         struct xen_pvcalls_request *req;
 532         int notify;
 533         int ret = -EINVAL;
 534         unsigned long flags;
 535
 536         fedata = mappass->fedata;
 537         /*
 538          * __pvcalls_back_accept can race against pvcalls_back_accept.
 539          * We only need to check the value of "cmd" on read. It could be
 540          * done atomically, but to simplify the code on the write side, we
 541          * use a spinlock.
 542          */
 543         spin_lock_irqsave(&mappass->copy_lock, flags);
 544         req = &mappass->reqcopy;
 545         if (req->cmd != PVCALLS_ACCEPT) {
 546                 spin_unlock_irqrestore(&mappass->copy_lock, flags);
 547                 return;
 548         }
 549         spin_unlock_irqrestore(&mappass->copy_lock, flags);
 550
 551         sock = sock_alloc();
 552         if (sock == NULL)
 553                 goto out_error;
 554         sock->type = mappass->sock->type;
 555         sock->ops = mappass->sock->ops;
 556
 557         ret = inet_accept(mappass->sock, sock, O_NONBLOCK, true);
 558         if (ret == -EAGAIN) {
 559                 sock_release(sock);
 560                 return;
 561         }
 562
 563         map = pvcalls_new_active_socket(fedata,
 564                                         req->u.accept.id_new,
 565                                         req->u.accept.ref,
 566                                         req->u.accept.evtchn,
 567                                         sock);
 568         if (!map) {
 569                 ret = -EFAULT;
 570                 goto out_error;
 571         }
 572
 573         map->sockpass = mappass;
 574         iow = &map->ioworker;
 575         atomic_inc(&map->read);
 576         atomic_inc(&map->io);
 577         queue_work(iow->wq, &iow->register_work);
 578
 579 out_error:
 580         rsp = RING_GET_RESPONSE(&fedata->ring, fedata->ring.rsp_prod_pvt++);
 581         rsp->req_id = req->req_id;
 582         rsp->cmd = req->cmd;
 583         rsp->u.accept.id = req->u.accept.id;
 584         rsp->ret = ret;
 585         RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&fedata->ring, notify);
 586         if (notify)
 587                 notify_remote_via_irq(fedata->irq);
 588
 589         mappass->reqcopy.cmd = 0;
 590 }
 591
 592 static void pvcalls_pass_sk_data_ready(struct sock *sock)
 593 {
 594         struct sockpass_mapping *mappass = sock->sk_user_data;
 595         struct pvcalls_fedata *fedata;
 596         struct xen_pvcalls_response *rsp;
 597         unsigned long flags;
 598         int notify;
 599
 600         if (mappass == NULL)
 601                 return;
 602
 603         fedata = mappass->fedata;
 604         spin_lock_irqsave(&mappass->copy_lock, flags);
 605         if (mappass->reqcopy.cmd == PVCALLS_POLL) {
 606                 rsp = RING_GET_RESPONSE(&fedata->ring,
 607                                         fedata->ring.rsp_prod_pvt++);
 608                 rsp->req_id = mappass->reqcopy.req_id;
 609                 rsp->u.poll.id = mappass->reqcopy.u.poll.id;
 610                 rsp->cmd = mappass->reqcopy.cmd;
 611                 rsp->ret = 0;
 612
 613                 mappass->reqcopy.cmd = 0;
 614                 spin_unlock_irqrestore(&mappass->copy_lock, flags);
 615
 616                 RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&fedata->ring, notify);
 617                 if (notify)
 618                         notify_remote_via_irq(mappass->fedata->irq);
 619         } else {
 620                 spin_unlock_irqrestore(&mappass->copy_lock, flags);
 621                 queue_work(mappass->wq, &mappass->register_work);
 622         }
 623 }
 624
 625 static int pvcalls_back_bind(struct xenbus_device *dev,
 626                              struct xen_pvcalls_request *req)
 627 {
 628         struct pvcalls_fedata *fedata;
 629         int ret;
 630         struct sockpass_mapping *map;
 631         struct xen_pvcalls_response *rsp;
 632
 633         fedata = dev_get_drvdata(&dev->dev);
 634
 635         map = kzalloc(sizeof(*map), GFP_KERNEL);
 636         if (map == NULL) {
 637                 ret = -ENOMEM;
 638                 goto out;
 639         }
 640
 641         INIT_WORK(&map->register_work, __pvcalls_back_accept);
 642         spin_lock_init(&map->copy_lock);
 643         map->wq = alloc_workqueue("pvcalls_wq", WQ_UNBOUND, 1);
 644         if (!map->wq) {
 645                 ret = -ENOMEM;
 646                 goto out;
 647         }
 648
 649         ret = sock_create(AF_INET, SOCK_STREAM, 0, &map->sock);
 650         if (ret < 0)
 651                 goto out;
 652
 653         ret = inet_bind(map->sock, (struct sockaddr *)&req->u.bind.addr,
 654                         req->u.bind.len);
 655         if (ret < 0)
 656                 goto out;
 657
 658         map->fedata = fedata;
 659         map->id = req->u.bind.id;
 660
 661         down(&fedata->socket_lock);
 662         ret = radix_tree_insert(&fedata->socketpass_mappings, map->id,
 663                                 map);
 664         up(&fedata->socket_lock);
 665         if (ret)
 666                 goto out;
 667
 668         write_lock_bh(&map->sock->sk->sk_callback_lock);
 669         map->saved_data_ready = map->sock->sk->sk_data_ready;
 670         map->sock->sk->sk_user_data = map;
 671         map->sock->sk->sk_data_ready = pvcalls_pass_sk_data_ready;
 672         write_unlock_bh(&map->sock->sk->sk_callback_lock);
 673
 674 out:
 675         if (ret) {
 676                 if (map && map->sock)
 677                         sock_release(map->sock);
 678                 if (map && map->wq)
 679                         destroy_workqueue(map->wq);
 680                 kfree(map);
 681         }
 682         rsp = RING_GET_RESPONSE(&fedata->ring, fedata->ring.rsp_prod_pvt++);
 683         rsp->req_id = req->req_id;
 684         rsp->cmd = req->cmd;
 685         rsp->u.bind.id = req->u.bind.id;
 686         rsp->ret = ret;
 687         return 0;
 688 }
 689
 690 static int pvcalls_back_listen(struct xenbus_device *dev,
 691                                struct xen_pvcalls_request *req)
 692 {
 693         struct pvcalls_fedata *fedata;
 694         int ret = -EINVAL;
 695         struct sockpass_mapping *map;
 696         struct xen_pvcalls_response *rsp;
 697
 698         fedata = dev_get_drvdata(&dev->dev);
 699
 700         down(&fedata->socket_lock);
 701         map = radix_tree_lookup(&fedata->socketpass_mappings, req->u.listen.id);
 702         up(&fedata->socket_lock);
 703         if (map == NULL)
 704                 goto out;
 705
 706         ret = inet_listen(map->sock, req->u.listen.backlog);
 707
 708 out:
 709         rsp = RING_GET_RESPONSE(&fedata->ring, fedata->ring.rsp_prod_pvt++);
 710         rsp->req_id = req->req_id;
 711         rsp->cmd = req->cmd;
 712         rsp->u.listen.id = req->u.listen.id;
 713         rsp->ret = ret;
 714         return 0;
 715 }
 716
 717 static int pvcalls_back_accept(struct xenbus_device *dev,
 718                                struct xen_pvcalls_request *req)
 719 {
 720         struct pvcalls_fedata *fedata;
 721         struct sockpass_mapping *mappass;
 722         int ret = -EINVAL;
 723         struct xen_pvcalls_response *rsp;
 724         unsigned long flags;
 725
 726         fedata = dev_get_drvdata(&dev->dev);
 727
 728         down(&fedata->socket_lock);
 729         mappass = radix_tree_lookup(&fedata->socketpass_mappings,
 730                 req->u.accept.id);
 731         up(&fedata->socket_lock);
 732         if (mappass == NULL)
 733                 goto out_error;
 734
 735         /*
 736          * Limitation of the current implementation: only support one
 737          * concurrent accept or poll call on one socket.
 738          */
 739         spin_lock_irqsave(&mappass->copy_lock, flags);
 740         if (mappass->reqcopy.cmd != 0) {
 741                 spin_unlock_irqrestore(&mappass->copy_lock, flags);
 742                 ret = -EINTR;
 743                 goto out_error;
 744         }
 745
 746         mappass->reqcopy = *req;
 747         spin_unlock_irqrestore(&mappass->copy_lock, flags);
 748         queue_work(mappass->wq, &mappass->register_work);
 749
 750         /* Tell the caller we don't need to send back a notification yet */
 751         return -1;
 752
 753 out_error:
 754         rsp = RING_GET_RESPONSE(&fedata->ring, fedata->ring.rsp_prod_pvt++);
 755         rsp->req_id = req->req_id;
 756         rsp->cmd = req->cmd;
 757         rsp->u.accept.id = req->u.accept.id;
 758         rsp->ret = ret;
 759         return 0;
 760 }
 761
 762 static int pvcalls_back_poll(struct xenbus_device *dev,
 763                              struct xen_pvcalls_request *req)
 764 {
 765         struct pvcalls_fedata *fedata;
 766         struct sockpass_mapping *mappass;
 767         struct xen_pvcalls_response *rsp;
 768         struct inet_connection_sock *icsk;
 769         struct request_sock_queue *queue;
 770         unsigned long flags;
 771         int ret;
 772         bool data;
 773
 774         fedata = dev_get_drvdata(&dev->dev);
 775
 776         down(&fedata->socket_lock);
 777         mappass = radix_tree_lookup(&fedata->socketpass_mappings,
 778                                     req->u.poll.id);
 779         up(&fedata->socket_lock);
 780         if (mappass == NULL)
 781                 return -EINVAL;
 782
 783         /*
 784          * Limitation of the current implementation: only support one
 785          * concurrent accept or poll call on one socket.
 786          */
 787         spin_lock_irqsave(&mappass->copy_lock, flags);
 788         if (mappass->reqcopy.cmd != 0) {
 789                 ret = -EINTR;
 790                 goto out;
 791         }
 792
 793         mappass->reqcopy = *req;
 794         icsk = inet_csk(mappass->sock->sk);
 795         queue = &icsk->icsk_accept_queue;
 796         data = READ_ONCE(queue->rskq_accept_head) != NULL;
 797         if (data) {
 798                 mappass->reqcopy.cmd = 0;
 799                 ret = 0;
 800                 goto out;
 801         }
 802         spin_unlock_irqrestore(&mappass->copy_lock, flags);
 803
 804         /* Tell the caller we don't need to send back a notification yet */
 805         return -1;
 806
 807 out:
 808         spin_unlock_irqrestore(&mappass->copy_lock, flags);
 809
 810         rsp = RING_GET_RESPONSE(&fedata->ring, fedata->ring.rsp_prod_pvt++);
 811         rsp->req_id = req->req_id;
 812         rsp->cmd = req->cmd;
 813         rsp->u.poll.id = req->u.poll.id;
 814         rsp->ret = ret;
 815         return 0;
 816 }
 817
 818 static int pvcalls_back_handle_cmd(struct xenbus_device *dev,
 819                                    struct xen_pvcalls_request *req)
 820 {
 821         int ret = 0;
 822
 823         switch (req->cmd) {
 824         case PVCALLS_SOCKET:
 825                 ret = pvcalls_back_socket(dev, req);
 826                 break;
 827         case PVCALLS_CONNECT:
 828                 ret = pvcalls_back_connect(dev, req);
 829                 break;
 830         case PVCALLS_RELEASE:
 831                 ret = pvcalls_back_release(dev, req);
 832                 break;
 833         case PVCALLS_BIND:
 834                 ret = pvcalls_back_bind(dev, req);
 835                 break;
 836         case PVCALLS_LISTEN:
 837                 ret = pvcalls_back_listen(dev, req);
 838                 break;
 839         case PVCALLS_ACCEPT:
 840                 ret = pvcalls_back_accept(dev, req);
 841                 break;
 842         case PVCALLS_POLL:
 843                 ret = pvcalls_back_poll(dev, req);
 844                 break;
 845         default:
 846         {
 847                 struct pvcalls_fedata *fedata;
 848                 struct xen_pvcalls_response *rsp;
 849
 850                 fedata = dev_get_drvdata(&dev->dev);
 851                 rsp = RING_GET_RESPONSE(
 852                                 &fedata->ring, fedata->ring.rsp_prod_pvt++);
 853                 rsp->req_id = req->req_id;
 854                 rsp->cmd = req->cmd;
 855                 rsp->ret = -ENOTSUPP;
 856                 break;
 857         }
 858         }
 859         return ret;
 860 }
 861
 862 static void pvcalls_back_work(struct pvcalls_fedata *fedata)
 863 {
 864         int notify, notify_all = 0, more = 1;
 865         struct xen_pvcalls_request req;
 866         struct xenbus_device *dev = fedata->dev;
 867
 868         while (more) {
 869                 while (RING_HAS_UNCONSUMED_REQUESTS(&fedata->ring)) {
 870                         RING_COPY_REQUEST(&fedata->ring,
 871                                           fedata->ring.req_cons++,
 872                                           &req);
 873
 874                         if (!pvcalls_back_handle_cmd(dev, &req)) {
 875                                 RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(
 876                                         &fedata->ring, notify);
 877                                 notify_all += notify;
 878                         }
 879                 }
 880
 881                 if (notify_all) {
 882                         notify_remote_via_irq(fedata->irq);
 883                         notify_all = 0;
 884                 }
 885
 886                 RING_FINAL_CHECK_FOR_REQUESTS(&fedata->ring, more);
 887         }
 888 }
 889
 890 static irqreturn_t pvcalls_back_event(int irq, void *dev_id)
 891 {
 892         struct xenbus_device *dev = dev_id;
 893         struct pvcalls_fedata *fedata = NULL;
 894         unsigned int eoi_flags = XEN_EOI_FLAG_SPURIOUS;
 895
 896         if (dev) {
 897                 fedata = dev_get_drvdata(&dev->dev);
 898                 if (fedata) {
 899                         pvcalls_back_work(fedata);
 900                         eoi_flags = 0;
 901                 }
 902         }
 903
 904         xen_irq_lateeoi(irq, eoi_flags);
 905
 906         return IRQ_HANDLED;
 907 }
 908
 909 static irqreturn_t pvcalls_back_conn_event(int irq, void *sock_map)
 910 {
 911         struct sock_mapping *map = sock_map;
 912         struct pvcalls_ioworker *iow;
 913
 914         if (map == NULL || map->sock == NULL || map->sock->sk == NULL ||
 915                 map->sock->sk->sk_user_data != map) {
 916                 xen_irq_lateeoi(irq, 0);
 917                 return IRQ_HANDLED;
 918         }
 919
 920         iow = &map->ioworker;
 921
 922         atomic_inc(&map->write);
 923         atomic_inc(&map->eoi);
 924         atomic_inc(&map->io);
 925         queue_work(iow->wq, &iow->register_work);
 926
 927         return IRQ_HANDLED;
 928 }
 929
 930 static int backend_connect(struct xenbus_device *dev)
 931 {
 932         int err, evtchn;
 933         grant_ref_t ring_ref;
 934         struct pvcalls_fedata *fedata = NULL;
 935
 936         fedata = kzalloc(sizeof(struct pvcalls_fedata), GFP_KERNEL);
 937         if (!fedata)
 938                 return -ENOMEM;
 939
 940         fedata->irq = -1;
 941         err = xenbus_scanf(XBT_NIL, dev->otherend, "port", "%u",
 942                            &evtchn);
 943         if (err != 1) {
 944                 err = -EINVAL;
 945                 xenbus_dev_fatal(dev, err, "reading %s/event-channel",
 946                                  dev->otherend);
 947                 goto error;
 948         }
 949
 950         err = xenbus_scanf(XBT_NIL, dev->otherend, "ring-ref", "%u", &ring_ref);
 951         if (err != 1) {
 952                 err = -EINVAL;
 953                 xenbus_dev_fatal(dev, err, "reading %s/ring-ref",
 954                                  dev->otherend);
 955                 goto error;
 956         }
 957
 958         err = bind_interdomain_evtchn_to_irq_lateeoi(dev->otherend_id, evtchn);
 959         if (err < 0)
 960                 goto error;
 961         fedata->irq = err;
 962
 963         err = request_threaded_irq(fedata->irq, NULL, pvcalls_back_event,
 964                                    IRQF_ONESHOT, "pvcalls-back", dev);
 965         if (err < 0)
 966                 goto error;
 967
 968         err = xenbus_map_ring_valloc(dev, &ring_ref, 1,
 969                                      (void **)&fedata->sring);
 970         if (err < 0)
 971                 goto error;
 972
 973         BACK_RING_INIT(&fedata->ring, fedata->sring, XEN_PAGE_SIZE * 1);
 974         fedata->dev = dev;
 975
 976         INIT_LIST_HEAD(&fedata->socket_mappings);
 977         INIT_RADIX_TREE(&fedata->socketpass_mappings, GFP_KERNEL);
 978         sema_init(&fedata->socket_lock, 1);
 979         dev_set_drvdata(&dev->dev, fedata);
 980
 981         down(&pvcalls_back_global.frontends_lock);
 982         list_add_tail(&fedata->list, &pvcalls_back_global.frontends);
 983         up(&pvcalls_back_global.frontends_lock);
 984
 985         return 0;
 986
 987  error:
 988         if (fedata->irq >= 0)
 989                 unbind_from_irqhandler(fedata->irq, dev);
 990         if (fedata->sring != NULL)
 991                 xenbus_unmap_ring_vfree(dev, fedata->sring);
 992         kfree(fedata);
 993         return err;
 994 }
 995
 996 static int backend_disconnect(struct xenbus_device *dev)
 997 {
 998         struct pvcalls_fedata *fedata;
 999         struct sock_mapping *map, *n;
1000         struct sockpass_mapping *mappass;
1001         struct radix_tree_iter iter;
1002         void **slot;
1003
1004
1005         fedata = dev_get_drvdata(&dev->dev);
1006
1007         down(&fedata->socket_lock);
1008         list_for_each_entry_safe(map, n, &fedata->socket_mappings, list) {
1009                 list_del(&map->list);
1010                 pvcalls_back_release_active(dev, fedata, map);
1011         }
1012
1013         radix_tree_for_each_slot(slot, &fedata->socketpass_mappings, &iter, 0) {
1014                 mappass = radix_tree_deref_slot(slot);
1015                 if (!mappass)
1016                         continue;
1017                 if (radix_tree_exception(mappass)) {
1018                         if (radix_tree_deref_retry(mappass))
1019                                 slot = radix_tree_iter_retry(&iter);
1020                 } else {
1021                         radix_tree_delete(&fedata->socketpass_mappings,
1022                                           mappass->id);
1023                         pvcalls_back_release_passive(dev, fedata, mappass);
1024                 }
1025         }
1026         up(&fedata->socket_lock);
1027
1028         unbind_from_irqhandler(fedata->irq, dev);
1029         xenbus_unmap_ring_vfree(dev, fedata->sring);
1030
1031         list_del(&fedata->list);
1032         kfree(fedata);
1033         dev_set_drvdata(&dev->dev, NULL);
1034
1035         return 0;
1036 }
1037
1038 static int pvcalls_back_probe(struct xenbus_device *dev,
1039                               const struct xenbus_device_id *id)
1040 {
1041         int err, abort;
1042         struct xenbus_transaction xbt;
1043
1044 again:
1045         abort = 1;
1046
1047         err = xenbus_transaction_start(&xbt);
1048         if (err) {
1049                 pr_warn("%s cannot create xenstore transaction\n", __func__);
1050                 return err;
1051         }
1052
1053         err = xenbus_printf(xbt, dev->nodename, "versions", "%s",
1054                             PVCALLS_VERSIONS);
1055         if (err) {
1056                 pr_warn("%s write out 'versions' failed\n", __func__);
1057                 goto abort;
1058         }
1059
1060         err = xenbus_printf(xbt, dev->nodename, "max-page-order", "%u",
1061                             MAX_RING_ORDER);
1062         if (err) {
1063                 pr_warn("%s write out 'max-page-order' failed\n", __func__);
1064                 goto abort;
1065         }
1066
1067         err = xenbus_printf(xbt, dev->nodename, "function-calls",
1068                             XENBUS_FUNCTIONS_CALLS);
1069         if (err) {
1070                 pr_warn("%s write out 'function-calls' failed\n", __func__);
1071                 goto abort;
1072         }
1073
1074         abort = 0;
1075 abort:
1076         err = xenbus_transaction_end(xbt, abort);
1077         if (err) {
1078                 if (err == -EAGAIN && !abort)
1079                         goto again;
1080                 pr_warn("%s cannot complete xenstore transaction\n", __func__);
1081                 return err;
1082         }
1083
1084         if (abort)
1085                 return -EFAULT;
1086
1087         xenbus_switch_state(dev, XenbusStateInitWait);
1088
1089         return 0;
1090 }
1091
1092 static void set_backend_state(struct xenbus_device *dev,
1093                               enum xenbus_state state)
1094 {
1095         while (dev->state != state) {
1096                 switch (dev->state) {
1097                 case XenbusStateClosed:
1098                         switch (state) {
1099                         case XenbusStateInitWait:
1100                         case XenbusStateConnected:
1101                                 xenbus_switch_state(dev, XenbusStateInitWait);
1102                                 break;
1103                         case XenbusStateClosing:
1104                                 xenbus_switch_state(dev, XenbusStateClosing);
1105                                 break;
1106                         default:
1107                                 WARN_ON(1);
1108                         }
1109                         break;
1110                 case XenbusStateInitWait:
1111                 case XenbusStateInitialised:
1112                         switch (state) {
1113                         case XenbusStateConnected:
1114                                 if (backend_connect(dev))
1115                                         return;
1116                                 xenbus_switch_state(dev, XenbusStateConnected);
1117                                 break;
1118                         case XenbusStateClosing:
1119                         case XenbusStateClosed:
1120                                 xenbus_switch_state(dev, XenbusStateClosing);
1121                                 break;
1122                         default:
1123                                 WARN_ON(1);
1124                         }
1125                         break;
1126                 case XenbusStateConnected:
1127                         switch (state) {
1128                         case XenbusStateInitWait:
1129                         case XenbusStateClosing:
1130                         case XenbusStateClosed:
1131                                 down(&pvcalls_back_global.frontends_lock);
1132                                 backend_disconnect(dev);
1133                                 up(&pvcalls_back_global.frontends_lock);
1134                                 xenbus_switch_state(dev, XenbusStateClosing);
1135                                 break;
1136                         default:
1137                                 WARN_ON(1);
1138                         }
1139                         break;
1140                 case XenbusStateClosing:
1141                         switch (state) {
1142                         case XenbusStateInitWait:
1143                         case XenbusStateConnected:
1144                         case XenbusStateClosed:
1145                                 xenbus_switch_state(dev, XenbusStateClosed);
1146                                 break;
1147                         default:
1148                                 WARN_ON(1);
1149                         }
1150                         break;
1151                 default:
1152                         WARN_ON(1);
1153                 }
1154         }
1155 }
1156
1157 static void pvcalls_back_changed(struct xenbus_device *dev,
1158                                  enum xenbus_state frontend_state)
1159 {
1160         switch (frontend_state) {
1161         case XenbusStateInitialising:
1162                 set_backend_state(dev, XenbusStateInitWait);
1163                 break;
1164
1165         case XenbusStateInitialised:
1166         case XenbusStateConnected:
1167                 set_backend_state(dev, XenbusStateConnected);
1168                 break;
1169
1170         case XenbusStateClosing:
1171                 set_backend_state(dev, XenbusStateClosing);
1172                 break;
1173
1174         case XenbusStateClosed:
1175                 set_backend_state(dev, XenbusStateClosed);
1176                 if (xenbus_dev_is_online(dev))
1177                         break;
1178                 device_unregister(&dev->dev);
1179                 break;
1180         case XenbusStateUnknown:
1181                 set_backend_state(dev, XenbusStateClosed);
1182                 device_unregister(&dev->dev);
1183                 break;
1184
1185         default:
1186                 xenbus_dev_fatal(dev, -EINVAL, "saw state %d at frontend",
1187                                  frontend_state);
1188                 break;
1189         }
1190 }
1191
1192 static int pvcalls_back_remove(struct xenbus_device *dev)
1193 {
1194         return 0;
1195 }
1196
1197 static int pvcalls_back_uevent(struct xenbus_device *xdev,
1198                                struct kobj_uevent_env *env)
1199 {
1200         return 0;
1201 }
1202
1203 static const struct xenbus_device_id pvcalls_back_ids[] = {
1204         { "pvcalls" },
1205         { "" }
1206 };
1207
1208 static struct xenbus_driver pvcalls_back_driver = {
1209         .ids = pvcalls_back_ids,
1210         .probe = pvcalls_back_probe,
1211         .remove = pvcalls_back_remove,
1212         .uevent = pvcalls_back_uevent,
1213         .otherend_changed = pvcalls_back_changed,
1214 };
1215
1216 static int __init pvcalls_back_init(void)
1217 {
1218         int ret;
1219
1220         if (!xen_domain())
1221                 return -ENODEV;
1222
1223         ret = xenbus_register_backend(&pvcalls_back_driver);
1224         if (ret < 0)
1225                 return ret;
1226
1227         sema_init(&pvcalls_back_global.frontends_lock, 1);
1228         INIT_LIST_HEAD(&pvcalls_back_global.frontends);
1229         return 0;
1230 }
1231 module_init(pvcalls_back_init);
1232
1233 static void __exit pvcalls_back_fin(void)
1234 {
1235         struct pvcalls_fedata *fedata, *nfedata;
1236
1237         down(&pvcalls_back_global.frontends_lock);
1238         list_for_each_entry_safe(fedata, nfedata,
1239                                  &pvcalls_back_global.frontends, list) {
1240                 backend_disconnect(fedata->dev);
1241         }
1242         up(&pvcalls_back_global.frontends_lock);
1243
1244         xenbus_unregister_driver(&pvcalls_back_driver);
1245 }
1246
1247 module_exit(pvcalls_back_fin);
1248
1249 MODULE_DESCRIPTION("Xen PV Calls backend driver");
1250 MODULE_AUTHOR("Stefano Stabellini <sstabellini@kernel.org>");
1251 MODULE_LICENSE("GPL");