drivers/xen/pvcalls-back.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * (c) 2017 Stefano Stabellini <stefano@aporeto.com>
   4  */
   5
   6 #include <linux/inet.h>
   7 #include <linux/kthread.h>
   8 #include <linux/list.h>
   9 #include <linux/radix-tree.h>
  10 #include <linux/module.h>
  11 #include <linux/semaphore.h>
  12 #include <linux/wait.h>
  13 #include <net/sock.h>
  14 #include <net/inet_common.h>
  15 #include <net/inet_connection_sock.h>
  16 #include <net/request_sock.h>
  17
  18 #include <xen/events.h>
  19 #include <xen/grant_table.h>
  20 #include <xen/xen.h>
  21 #include <xen/xenbus.h>
  22 #include <xen/interface/io/pvcalls.h>
  23
  24 #define PVCALLS_VERSIONS "1"
  25 #define MAX_RING_ORDER XENBUS_MAX_RING_GRANT_ORDER
  26
  27 static struct pvcalls_back_global {
  28         struct list_head frontends;
  29         struct semaphore frontends_lock;
  30 } pvcalls_back_global;
  31
  32 /*
  33  * Per-frontend data structure. It contains pointers to the command
  34  * ring, its event channel, a list of active sockets and a tree of
  35  * passive sockets.
  36  */
  37 struct pvcalls_fedata {
  38         struct list_head list;
  39         struct xenbus_device *dev;
  40         struct xen_pvcalls_sring *sring;
  41         struct xen_pvcalls_back_ring ring;
  42         int irq;
  43         struct list_head socket_mappings;
  44         struct radix_tree_root socketpass_mappings;
  45         struct semaphore socket_lock;
  46 };
  47
  48 struct pvcalls_ioworker {
  49         struct work_struct register_work;
  50         struct workqueue_struct *wq;
  51 };
  52
  53 struct sock_mapping {
  54         struct list_head list;
  55         struct pvcalls_fedata *fedata;
  56         struct sockpass_mapping *sockpass;
  57         struct socket *sock;
  58         uint64_t id;
  59         grant_ref_t ref;
  60         struct pvcalls_data_intf *ring;
  61         void *bytes;
  62         struct pvcalls_data data;
  63         uint32_t ring_order;
  64         int irq;
  65         atomic_t read;
  66         atomic_t write;
  67         atomic_t io;
  68         atomic_t release;
  69         atomic_t eoi;
  70         void (*saved_data_ready)(struct sock *sk);
  71         struct pvcalls_ioworker ioworker;
  72 };
  73
  74 struct sockpass_mapping {
  75         struct list_head list;
  76         struct pvcalls_fedata *fedata;
  77         struct socket *sock;
  78         uint64_t id;
  79         struct xen_pvcalls_request reqcopy;
  80         spinlock_t copy_lock;
  81         struct workqueue_struct *wq;
  82         struct work_struct register_work;
  83         void (*saved_data_ready)(struct sock *sk);
  84 };
  85
  86 static irqreturn_t pvcalls_back_conn_event(int irq, void *sock_map);
  87 static int pvcalls_back_release_active(struct xenbus_device *dev,
  88                                        struct pvcalls_fedata *fedata,
  89                                        struct sock_mapping *map);
  90
  91 static bool pvcalls_conn_back_read(void *opaque)
  92 {
  93         struct sock_mapping *map = (struct sock_mapping *)opaque;
  94         struct msghdr msg;
  95         struct kvec vec[2];
  96         RING_IDX cons, prod, size, wanted, array_size, masked_prod, masked_cons;
  97         int32_t error;
  98         struct pvcalls_data_intf *intf = map->ring;
  99         struct pvcalls_data *data = &map->data;
 100         unsigned long flags;
 101         int ret;
 102
 103         array_size = XEN_FLEX_RING_SIZE(map->ring_order);
 104         cons = intf->in_cons;
 105         prod = intf->in_prod;
 106         error = intf->in_error;
 107         /* read the indexes first, then deal with the data */
 108         virt_mb();
 109
 110         if (error)
 111                 return false;
 112
 113         size = pvcalls_queued(prod, cons, array_size);
 114         if (size >= array_size)
 115                 return false;
 116         spin_lock_irqsave(&map->sock->sk->sk_receive_queue.lock, flags);
 117         if (skb_queue_empty(&map->sock->sk->sk_receive_queue)) {
 118                 atomic_set(&map->read, 0);
 119                 spin_unlock_irqrestore(&map->sock->sk->sk_receive_queue.lock,
 120                                 flags);
 121                 return true;
 122         }
 123         spin_unlock_irqrestore(&map->sock->sk->sk_receive_queue.lock, flags);
 124         wanted = array_size - size;
 125         masked_prod = pvcalls_mask(prod, array_size);
 126         masked_cons = pvcalls_mask(cons, array_size);
 127
 128         memset(&msg, 0, sizeof(msg));
 129         if (masked_prod < masked_cons) {
 130                 vec[0].iov_base = data->in + masked_prod;
 131                 vec[0].iov_len = wanted;
 132                 iov_iter_kvec(&msg.msg_iter, WRITE, vec, 1, wanted);
 133         } else {
 134                 vec[0].iov_base = data->in + masked_prod;
 135                 vec[0].iov_len = array_size - masked_prod;
 136                 vec[1].iov_base = data->in;
 137                 vec[1].iov_len = wanted - vec[0].iov_len;
 138                 iov_iter_kvec(&msg.msg_iter, WRITE, vec, 2, wanted);
 139         }
 140
 141         atomic_set(&map->read, 0);
 142         ret = inet_recvmsg(map->sock, &msg, wanted, MSG_DONTWAIT);
 143         WARN_ON(ret > wanted);
 144         if (ret == -EAGAIN) /* shouldn't happen */
 145                 return true;
 146         if (!ret)
 147                 ret = -ENOTCONN;
 148         spin_lock_irqsave(&map->sock->sk->sk_receive_queue.lock, flags);
 149         if (ret > 0 && !skb_queue_empty(&map->sock->sk->sk_receive_queue))
 150                 atomic_inc(&map->read);
 151         spin_unlock_irqrestore(&map->sock->sk->sk_receive_queue.lock, flags);
 152
 153         /* write the data, then modify the indexes */
 154         virt_wmb();
 155         if (ret < 0) {
 156                 atomic_set(&map->read, 0);
 157                 intf->in_error = ret;
 158         } else
 159                 intf->in_prod = prod + ret;
 160         /* update the indexes, then notify the other end */
 161         virt_wmb();
 162         notify_remote_via_irq(map->irq);
 163
 164         return true;
 165 }
 166
 167 static bool pvcalls_conn_back_write(struct sock_mapping *map)
 168 {
 169         struct pvcalls_data_intf *intf = map->ring;
 170         struct pvcalls_data *data = &map->data;
 171         struct msghdr msg;
 172         struct kvec vec[2];
 173         RING_IDX cons, prod, size, array_size;
 174         int ret;
 175
 176         cons = intf->out_cons;
 177         prod = intf->out_prod;
 178         /* read the indexes before dealing with the data */
 179         virt_mb();
 180
 181         array_size = XEN_FLEX_RING_SIZE(map->ring_order);
 182         size = pvcalls_queued(prod, cons, array_size);
 183         if (size == 0)
 184                 return false;
 185
 186         memset(&msg, 0, sizeof(msg));
 187         msg.msg_flags |= MSG_DONTWAIT;
 188         if (pvcalls_mask(prod, array_size) > pvcalls_mask(cons, array_size)) {
 189                 vec[0].iov_base = data->out + pvcalls_mask(cons, array_size);
 190                 vec[0].iov_len = size;
 191                 iov_iter_kvec(&msg.msg_iter, READ, vec, 1, size);
 192         } else {
 193                 vec[0].iov_base = data->out + pvcalls_mask(cons, array_size);
 194                 vec[0].iov_len = array_size - pvcalls_mask(cons, array_size);
 195                 vec[1].iov_base = data->out;
 196                 vec[1].iov_len = size - vec[0].iov_len;
 197                 iov_iter_kvec(&msg.msg_iter, READ, vec, 2, size);
 198         }
 199
 200         atomic_set(&map->write, 0);
 201         ret = inet_sendmsg(map->sock, &msg, size);
 202         if (ret == -EAGAIN) {
 203                 atomic_inc(&map->write);
 204                 atomic_inc(&map->io);
 205                 return true;
 206         }
 207
 208         /* write the data, then update the indexes */
 209         virt_wmb();
 210         if (ret < 0) {
 211                 intf->out_error = ret;
 212         } else {
 213                 intf->out_error = 0;
 214                 intf->out_cons = cons + ret;
 215                 prod = intf->out_prod;
 216         }
 217         /* update the indexes, then notify the other end */
 218         virt_wmb();
 219         if (prod != cons + ret) {
 220                 atomic_inc(&map->write);
 221                 atomic_inc(&map->io);
 222         }
 223         notify_remote_via_irq(map->irq);
 224
 225         return true;
 226 }
 227
 228 static void pvcalls_back_ioworker(struct work_struct *work)
 229 {
 230         struct pvcalls_ioworker *ioworker = container_of(work,
 231                 struct pvcalls_ioworker, register_work);
 232         struct sock_mapping *map = container_of(ioworker, struct sock_mapping,
 233                 ioworker);
 234         unsigned int eoi_flags = XEN_EOI_FLAG_SPURIOUS;
 235
 236         while (atomic_read(&map->io) > 0) {
 237                 if (atomic_read(&map->release) > 0) {
 238                         atomic_set(&map->release, 0);
 239                         return;
 240                 }
 241
 242                 if (atomic_read(&map->read) > 0 &&
 243                     pvcalls_conn_back_read(map))
 244                         eoi_flags = 0;
 245                 if (atomic_read(&map->write) > 0 &&
 246                     pvcalls_conn_back_write(map))
 247                         eoi_flags = 0;
 248
 249                 if (atomic_read(&map->eoi) > 0 && !atomic_read(&map->write)) {
 250                         atomic_set(&map->eoi, 0);
 251                         xen_irq_lateeoi(map->irq, eoi_flags);
 252                         eoi_flags = XEN_EOI_FLAG_SPURIOUS;
 253                 }
 254
 255                 atomic_dec(&map->io);
 256         }
 257 }
 258
 259 static int pvcalls_back_socket(struct xenbus_device *dev,
 260                 struct xen_pvcalls_request *req)
 261 {
 262         struct pvcalls_fedata *fedata;
 263         int ret;
 264         struct xen_pvcalls_response *rsp;
 265
 266         fedata = dev_get_drvdata(&dev->dev);
 267
 268         if (req->u.socket.domain != AF_INET ||
 269             req->u.socket.type != SOCK_STREAM ||
 270             (req->u.socket.protocol != IPPROTO_IP &&
 271              req->u.socket.protocol != AF_INET))
 272                 ret = -EAFNOSUPPORT;
 273         else
 274                 ret = 0;
 275
 276         /* leave the actual socket allocation for later */
 277
 278         rsp = RING_GET_RESPONSE(&fedata->ring, fedata->ring.rsp_prod_pvt++);
 279         rsp->req_id = req->req_id;
 280         rsp->cmd = req->cmd;
 281         rsp->u.socket.id = req->u.socket.id;
 282         rsp->ret = ret;
 283
 284         return 0;
 285 }
 286
 287 static void pvcalls_sk_state_change(struct sock *sock)
 288 {
 289         struct sock_mapping *map = sock->sk_user_data;
 290
 291         if (map == NULL)
 292                 return;
 293
 294         atomic_inc(&map->read);
 295         notify_remote_via_irq(map->irq);
 296 }
 297
 298 static void pvcalls_sk_data_ready(struct sock *sock)
 299 {
 300         struct sock_mapping *map = sock->sk_user_data;
 301         struct pvcalls_ioworker *iow;
 302
 303         if (map == NULL)
 304                 return;
 305
 306         iow = &map->ioworker;
 307         atomic_inc(&map->read);
 308         atomic_inc(&map->io);
 309         queue_work(iow->wq, &iow->register_work);
 310 }
 311
 312 static struct sock_mapping *pvcalls_new_active_socket(
 313                 struct pvcalls_fedata *fedata,
 314                 uint64_t id,
 315                 grant_ref_t ref,
 316                 evtchn_port_t evtchn,
 317                 struct socket *sock)
 318 {
 319         int ret;
 320         struct sock_mapping *map;
 321         void *page;
 322
 323         map = kzalloc(sizeof(*map), GFP_KERNEL);
 324         if (map == NULL)
 325                 return NULL;
 326
 327         map->fedata = fedata;
 328         map->sock = sock;
 329         map->id = id;
 330         map->ref = ref;
 331
 332         ret = xenbus_map_ring_valloc(fedata->dev, &ref, 1, &page);
 333         if (ret < 0)
 334                 goto out;
 335         map->ring = page;
 336         map->ring_order = map->ring->ring_order;
 337         /* first read the order, then map the data ring */
 338         virt_rmb();
 339         if (map->ring_order > MAX_RING_ORDER) {
 340                 pr_warn("%s frontend requested ring_order %u, which is > MAX (%u)\n",
 341                                 __func__, map->ring_order, MAX_RING_ORDER);
 342                 goto out;
 343         }
 344         ret = xenbus_map_ring_valloc(fedata->dev, map->ring->ref,
 345                                      (1 << map->ring_order), &page);
 346         if (ret < 0)
 347                 goto out;
 348         map->bytes = page;
 349
 350         ret = bind_interdomain_evtchn_to_irqhandler_lateeoi(
 351                         fedata->dev, evtchn,
 352                         pvcalls_back_conn_event, 0, "pvcalls-backend", 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 = READ_ONCE(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         unsigned int eoi_flags = XEN_EOI_FLAG_SPURIOUS;
 887
 888         if (dev) {
 889                 fedata = dev_get_drvdata(&dev->dev);
 890                 if (fedata) {
 891                         pvcalls_back_work(fedata);
 892                         eoi_flags = 0;
 893                 }
 894         }
 895
 896         xen_irq_lateeoi(irq, eoi_flags);
 897
 898         return IRQ_HANDLED;
 899 }
 900
 901 static irqreturn_t pvcalls_back_conn_event(int irq, void *sock_map)
 902 {
 903         struct sock_mapping *map = sock_map;
 904         struct pvcalls_ioworker *iow;
 905
 906         if (map == NULL || map->sock == NULL || map->sock->sk == NULL ||
 907                 map->sock->sk->sk_user_data != map) {
 908                 xen_irq_lateeoi(irq, 0);
 909                 return IRQ_HANDLED;
 910         }
 911
 912         iow = &map->ioworker;
 913
 914         atomic_inc(&map->write);
 915         atomic_inc(&map->eoi);
 916         atomic_inc(&map->io);
 917         queue_work(iow->wq, &iow->register_work);
 918
 919         return IRQ_HANDLED;
 920 }
 921
 922 static int backend_connect(struct xenbus_device *dev)
 923 {
 924         int err;
 925         evtchn_port_t evtchn;
 926         grant_ref_t ring_ref;
 927         struct pvcalls_fedata *fedata = NULL;
 928
 929         fedata = kzalloc(sizeof(struct pvcalls_fedata), GFP_KERNEL);
 930         if (!fedata)
 931                 return -ENOMEM;
 932
 933         fedata->irq = -1;
 934         err = xenbus_scanf(XBT_NIL, dev->otherend, "port", "%u",
 935                            &evtchn);
 936         if (err != 1) {
 937                 err = -EINVAL;
 938                 xenbus_dev_fatal(dev, err, "reading %s/event-channel",
 939                                  dev->otherend);
 940                 goto error;
 941         }
 942
 943         err = xenbus_scanf(XBT_NIL, dev->otherend, "ring-ref", "%u", &ring_ref);
 944         if (err != 1) {
 945                 err = -EINVAL;
 946                 xenbus_dev_fatal(dev, err, "reading %s/ring-ref",
 947                                  dev->otherend);
 948                 goto error;
 949         }
 950
 951         err = bind_interdomain_evtchn_to_irq_lateeoi(dev, evtchn);
 952         if (err < 0)
 953                 goto error;
 954         fedata->irq = err;
 955
 956         err = request_threaded_irq(fedata->irq, NULL, pvcalls_back_event,
 957                                    IRQF_ONESHOT, "pvcalls-back", dev);
 958         if (err < 0)
 959                 goto error;
 960
 961         err = xenbus_map_ring_valloc(dev, &ring_ref, 1,
 962                                      (void **)&fedata->sring);
 963         if (err < 0)
 964                 goto error;
 965
 966         BACK_RING_INIT(&fedata->ring, fedata->sring, XEN_PAGE_SIZE * 1);
 967         fedata->dev = dev;
 968
 969         INIT_LIST_HEAD(&fedata->socket_mappings);
 970         INIT_RADIX_TREE(&fedata->socketpass_mappings, GFP_KERNEL);
 971         sema_init(&fedata->socket_lock, 1);
 972         dev_set_drvdata(&dev->dev, fedata);
 973
 974         down(&pvcalls_back_global.frontends_lock);
 975         list_add_tail(&fedata->list, &pvcalls_back_global.frontends);
 976         up(&pvcalls_back_global.frontends_lock);
 977
 978         return 0;
 979
 980  error:
 981         if (fedata->irq >= 0)
 982                 unbind_from_irqhandler(fedata->irq, dev);
 983         if (fedata->sring != NULL)
 984                 xenbus_unmap_ring_vfree(dev, fedata->sring);
 985         kfree(fedata);
 986         return err;
 987 }
 988
 989 static int backend_disconnect(struct xenbus_device *dev)
 990 {
 991         struct pvcalls_fedata *fedata;
 992         struct sock_mapping *map, *n;
 993         struct sockpass_mapping *mappass;
 994         struct radix_tree_iter iter;
 995         void **slot;
 996
 997
 998         fedata = dev_get_drvdata(&dev->dev);
 999
1000         down(&fedata->socket_lock);
1001         list_for_each_entry_safe(map, n, &fedata->socket_mappings, list) {
1002                 list_del(&map->list);
1003                 pvcalls_back_release_active(dev, fedata, map);
1004         }
1005
1006         radix_tree_for_each_slot(slot, &fedata->socketpass_mappings, &iter, 0) {
1007                 mappass = radix_tree_deref_slot(slot);
1008                 if (!mappass)
1009                         continue;
1010                 if (radix_tree_exception(mappass)) {
1011                         if (radix_tree_deref_retry(mappass))
1012                                 slot = radix_tree_iter_retry(&iter);
1013                 } else {
1014                         radix_tree_delete(&fedata->socketpass_mappings,
1015                                           mappass->id);
1016                         pvcalls_back_release_passive(dev, fedata, mappass);
1017                 }
1018         }
1019         up(&fedata->socket_lock);
1020
1021         unbind_from_irqhandler(fedata->irq, dev);
1022         xenbus_unmap_ring_vfree(dev, fedata->sring);
1023
1024         list_del(&fedata->list);
1025         kfree(fedata);
1026         dev_set_drvdata(&dev->dev, NULL);
1027
1028         return 0;
1029 }
1030
1031 static int pvcalls_back_probe(struct xenbus_device *dev,
1032                               const struct xenbus_device_id *id)
1033 {
1034         int err, abort;
1035         struct xenbus_transaction xbt;
1036
1037 again:
1038         abort = 1;
1039
1040         err = xenbus_transaction_start(&xbt);
1041         if (err) {
1042                 pr_warn("%s cannot create xenstore transaction\n", __func__);
1043                 return err;
1044         }
1045
1046         err = xenbus_printf(xbt, dev->nodename, "versions", "%s",
1047                             PVCALLS_VERSIONS);
1048         if (err) {
1049                 pr_warn("%s write out 'versions' failed\n", __func__);
1050                 goto abort;
1051         }
1052
1053         err = xenbus_printf(xbt, dev->nodename, "max-page-order", "%u",
1054                             MAX_RING_ORDER);
1055         if (err) {
1056                 pr_warn("%s write out 'max-page-order' failed\n", __func__);
1057                 goto abort;
1058         }
1059
1060         err = xenbus_printf(xbt, dev->nodename, "function-calls",
1061                             XENBUS_FUNCTIONS_CALLS);
1062         if (err) {
1063                 pr_warn("%s write out 'function-calls' failed\n", __func__);
1064                 goto abort;
1065         }
1066
1067         abort = 0;
1068 abort:
1069         err = xenbus_transaction_end(xbt, abort);
1070         if (err) {
1071                 if (err == -EAGAIN && !abort)
1072                         goto again;
1073                 pr_warn("%s cannot complete xenstore transaction\n", __func__);
1074                 return err;
1075         }
1076
1077         if (abort)
1078                 return -EFAULT;
1079
1080         xenbus_switch_state(dev, XenbusStateInitWait);
1081
1082         return 0;
1083 }
1084
1085 static void set_backend_state(struct xenbus_device *dev,
1086                               enum xenbus_state state)
1087 {
1088         while (dev->state != state) {
1089                 switch (dev->state) {
1090                 case XenbusStateClosed:
1091                         switch (state) {
1092                         case XenbusStateInitWait:
1093                         case XenbusStateConnected:
1094                                 xenbus_switch_state(dev, XenbusStateInitWait);
1095                                 break;
1096                         case XenbusStateClosing:
1097                                 xenbus_switch_state(dev, XenbusStateClosing);
1098                                 break;
1099                         default:
1100                                 WARN_ON(1);
1101                         }
1102                         break;
1103                 case XenbusStateInitWait:
1104                 case XenbusStateInitialised:
1105                         switch (state) {
1106                         case XenbusStateConnected:
1107                                 if (backend_connect(dev))
1108                                         return;
1109                                 xenbus_switch_state(dev, XenbusStateConnected);
1110                                 break;
1111                         case XenbusStateClosing:
1112                         case XenbusStateClosed:
1113                                 xenbus_switch_state(dev, XenbusStateClosing);
1114                                 break;
1115                         default:
1116                                 WARN_ON(1);
1117                         }
1118                         break;
1119                 case XenbusStateConnected:
1120                         switch (state) {
1121                         case XenbusStateInitWait:
1122                         case XenbusStateClosing:
1123                         case XenbusStateClosed:
1124                                 down(&pvcalls_back_global.frontends_lock);
1125                                 backend_disconnect(dev);
1126                                 up(&pvcalls_back_global.frontends_lock);
1127                                 xenbus_switch_state(dev, XenbusStateClosing);
1128                                 break;
1129                         default:
1130                                 WARN_ON(1);
1131                         }
1132                         break;
1133                 case XenbusStateClosing:
1134                         switch (state) {
1135                         case XenbusStateInitWait:
1136                         case XenbusStateConnected:
1137                         case XenbusStateClosed:
1138                                 xenbus_switch_state(dev, XenbusStateClosed);
1139                                 break;
1140                         default:
1141                                 WARN_ON(1);
1142                         }
1143                         break;
1144                 default:
1145                         WARN_ON(1);
1146                 }
1147         }
1148 }
1149
1150 static void pvcalls_back_changed(struct xenbus_device *dev,
1151                                  enum xenbus_state frontend_state)
1152 {
1153         switch (frontend_state) {
1154         case XenbusStateInitialising:
1155                 set_backend_state(dev, XenbusStateInitWait);
1156                 break;
1157
1158         case XenbusStateInitialised:
1159         case XenbusStateConnected:
1160                 set_backend_state(dev, XenbusStateConnected);
1161                 break;
1162
1163         case XenbusStateClosing:
1164                 set_backend_state(dev, XenbusStateClosing);
1165                 break;
1166
1167         case XenbusStateClosed:
1168                 set_backend_state(dev, XenbusStateClosed);
1169                 if (xenbus_dev_is_online(dev))
1170                         break;
1171                 device_unregister(&dev->dev);
1172                 break;
1173         case XenbusStateUnknown:
1174                 set_backend_state(dev, XenbusStateClosed);
1175                 device_unregister(&dev->dev);
1176                 break;
1177
1178         default:
1179                 xenbus_dev_fatal(dev, -EINVAL, "saw state %d at frontend",
1180                                  frontend_state);
1181                 break;
1182         }
1183 }
1184
1185 static int pvcalls_back_remove(struct xenbus_device *dev)
1186 {
1187         return 0;
1188 }
1189
1190 static int pvcalls_back_uevent(struct xenbus_device *xdev,
1191                                struct kobj_uevent_env *env)
1192 {
1193         return 0;
1194 }
1195
1196 static const struct xenbus_device_id pvcalls_back_ids[] = {
1197         { "pvcalls" },
1198         { "" }
1199 };
1200
1201 static struct xenbus_driver pvcalls_back_driver = {
1202         .ids = pvcalls_back_ids,
1203         .probe = pvcalls_back_probe,
1204         .remove = pvcalls_back_remove,
1205         .uevent = pvcalls_back_uevent,
1206         .otherend_changed = pvcalls_back_changed,
1207 };
1208
1209 static int __init pvcalls_back_init(void)
1210 {
1211         int ret;
1212
1213         if (!xen_domain())
1214                 return -ENODEV;
1215
1216         ret = xenbus_register_backend(&pvcalls_back_driver);
1217         if (ret < 0)
1218                 return ret;
1219
1220         sema_init(&pvcalls_back_global.frontends_lock, 1);
1221         INIT_LIST_HEAD(&pvcalls_back_global.frontends);
1222         return 0;
1223 }
1224 module_init(pvcalls_back_init);
1225
1226 static void __exit pvcalls_back_fin(void)
1227 {
1228         struct pvcalls_fedata *fedata, *nfedata;
1229
1230         down(&pvcalls_back_global.frontends_lock);
1231         list_for_each_entry_safe(fedata, nfedata,
1232                                  &pvcalls_back_global.frontends, list) {
1233                 backend_disconnect(fedata->dev);
1234         }
1235         up(&pvcalls_back_global.frontends_lock);
1236
1237         xenbus_unregister_driver(&pvcalls_back_driver);
1238 }
1239
1240 module_exit(pvcalls_back_fin);
1241
1242 MODULE_DESCRIPTION("Xen PV Calls backend driver");
1243 MODULE_AUTHOR("Stefano Stabellini <sstabellini@kernel.org>");
1244 MODULE_LICENSE("GPL");