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, READ, 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, READ, 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, WRITE, 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, WRITE, 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                 sock_release(sock);
 326                 return NULL;
 327         }
 328
 329         map->fedata = fedata;
 330         map->sock = sock;
 331         map->id = id;
 332         map->ref = ref;
 333
 334         ret = xenbus_map_ring_valloc(fedata->dev, &ref, 1, &page);
 335         if (ret < 0)
 336                 goto out;
 337         map->ring = page;
 338         map->ring_order = map->ring->ring_order;
 339         /* first read the order, then map the data ring */
 340         virt_rmb();
 341         if (map->ring_order > MAX_RING_ORDER) {
 342                 pr_warn("%s frontend requested ring_order %u, which is > MAX (%u)\n",
 343                                 __func__, map->ring_order, MAX_RING_ORDER);
 344                 goto out;
 345         }
 346         ret = xenbus_map_ring_valloc(fedata->dev, map->ring->ref,
 347                                      (1 << map->ring_order), &page);
 348         if (ret < 0)
 349                 goto out;
 350         map->bytes = page;
 351
 352         ret = bind_interdomain_evtchn_to_irqhandler_lateeoi(
 353                         fedata->dev->otherend_id, evtchn,
 354                         pvcalls_back_conn_event, 0, "pvcalls-backend", map);
 355         if (ret < 0)
 356                 goto out;
 357         map->irq = ret;
 358
 359         map->data.in = map->bytes;
 360         map->data.out = map->bytes + XEN_FLEX_RING_SIZE(map->ring_order);
 361
 362         map->ioworker.wq = alloc_workqueue("pvcalls_io", WQ_UNBOUND, 1);
 363         if (!map->ioworker.wq)
 364                 goto out;
 365         atomic_set(&map->io, 1);
 366         INIT_WORK(&map->ioworker.register_work, pvcalls_back_ioworker);
 367
 368         down(&fedata->socket_lock);
 369         list_add_tail(&map->list, &fedata->socket_mappings);
 370         up(&fedata->socket_lock);
 371
 372         write_lock_bh(&map->sock->sk->sk_callback_lock);
 373         map->saved_data_ready = map->sock->sk->sk_data_ready;
 374         map->sock->sk->sk_user_data = map;
 375         map->sock->sk->sk_data_ready = pvcalls_sk_data_ready;
 376         map->sock->sk->sk_state_change = pvcalls_sk_state_change;
 377         write_unlock_bh(&map->sock->sk->sk_callback_lock);
 378
 379         return map;
 380 out:
 381         down(&fedata->socket_lock);
 382         list_del(&map->list);
 383         pvcalls_back_release_active(fedata->dev, fedata, map);
 384         up(&fedata->socket_lock);
 385         return NULL;
 386 }
 387
 388 static int pvcalls_back_connect(struct xenbus_device *dev,
 389                                 struct xen_pvcalls_request *req)
 390 {
 391         struct pvcalls_fedata *fedata;
 392         int ret = -EINVAL;
 393         struct socket *sock;
 394         struct sock_mapping *map;
 395         struct xen_pvcalls_response *rsp;
 396         struct sockaddr *sa = (struct sockaddr *)&req->u.connect.addr;
 397
 398         fedata = dev_get_drvdata(&dev->dev);
 399
 400         if (req->u.connect.len < sizeof(sa->sa_family) ||
 401             req->u.connect.len > sizeof(req->u.connect.addr) ||
 402             sa->sa_family != AF_INET)
 403                 goto out;
 404
 405         ret = sock_create(AF_INET, SOCK_STREAM, 0, &sock);
 406         if (ret < 0)
 407                 goto out;
 408         ret = inet_stream_connect(sock, sa, req->u.connect.len, 0);
 409         if (ret < 0) {
 410                 sock_release(sock);
 411                 goto out;
 412         }
 413
 414         map = pvcalls_new_active_socket(fedata,
 415                                         req->u.connect.id,
 416                                         req->u.connect.ref,
 417                                         req->u.connect.evtchn,
 418                                         sock);
 419         if (!map)
 420                 ret = -EFAULT;
 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                 goto out_error;
 562         }
 563
 564         map->sockpass = mappass;
 565         iow = &map->ioworker;
 566         atomic_inc(&map->read);
 567         atomic_inc(&map->io);
 568         queue_work(iow->wq, &iow->register_work);
 569
 570 out_error:
 571         rsp = RING_GET_RESPONSE(&fedata->ring, fedata->ring.rsp_prod_pvt++);
 572         rsp->req_id = req->req_id;
 573         rsp->cmd = req->cmd;
 574         rsp->u.accept.id = req->u.accept.id;
 575         rsp->ret = ret;
 576         RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&fedata->ring, notify);
 577         if (notify)
 578                 notify_remote_via_irq(fedata->irq);
 579
 580         mappass->reqcopy.cmd = 0;
 581 }
 582
 583 static void pvcalls_pass_sk_data_ready(struct sock *sock)
 584 {
 585         struct sockpass_mapping *mappass = sock->sk_user_data;
 586         struct pvcalls_fedata *fedata;
 587         struct xen_pvcalls_response *rsp;
 588         unsigned long flags;
 589         int notify;
 590
 591         if (mappass == NULL)
 592                 return;
 593
 594         fedata = mappass->fedata;
 595         spin_lock_irqsave(&mappass->copy_lock, flags);
 596         if (mappass->reqcopy.cmd == PVCALLS_POLL) {
 597                 rsp = RING_GET_RESPONSE(&fedata->ring,
 598                                         fedata->ring.rsp_prod_pvt++);
 599                 rsp->req_id = mappass->reqcopy.req_id;
 600                 rsp->u.poll.id = mappass->reqcopy.u.poll.id;
 601                 rsp->cmd = mappass->reqcopy.cmd;
 602                 rsp->ret = 0;
 603
 604                 mappass->reqcopy.cmd = 0;
 605                 spin_unlock_irqrestore(&mappass->copy_lock, flags);
 606
 607                 RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&fedata->ring, notify);
 608                 if (notify)
 609                         notify_remote_via_irq(mappass->fedata->irq);
 610         } else {
 611                 spin_unlock_irqrestore(&mappass->copy_lock, flags);
 612                 queue_work(mappass->wq, &mappass->register_work);
 613         }
 614 }
 615
 616 static int pvcalls_back_bind(struct xenbus_device *dev,
 617                              struct xen_pvcalls_request *req)
 618 {
 619         struct pvcalls_fedata *fedata;
 620         int ret;
 621         struct sockpass_mapping *map;
 622         struct xen_pvcalls_response *rsp;
 623
 624         fedata = dev_get_drvdata(&dev->dev);
 625
 626         map = kzalloc(sizeof(*map), GFP_KERNEL);
 627         if (map == NULL) {
 628                 ret = -ENOMEM;
 629                 goto out;
 630         }
 631
 632         INIT_WORK(&map->register_work, __pvcalls_back_accept);
 633         spin_lock_init(&map->copy_lock);
 634         map->wq = alloc_workqueue("pvcalls_wq", WQ_UNBOUND, 1);
 635         if (!map->wq) {
 636                 ret = -ENOMEM;
 637                 goto out;
 638         }
 639
 640         ret = sock_create(AF_INET, SOCK_STREAM, 0, &map->sock);
 641         if (ret < 0)
 642                 goto out;
 643
 644         ret = inet_bind(map->sock, (struct sockaddr *)&req->u.bind.addr,
 645                         req->u.bind.len);
 646         if (ret < 0)
 647                 goto out;
 648
 649         map->fedata = fedata;
 650         map->id = req->u.bind.id;
 651
 652         down(&fedata->socket_lock);
 653         ret = radix_tree_insert(&fedata->socketpass_mappings, map->id,
 654                                 map);
 655         up(&fedata->socket_lock);
 656         if (ret)
 657                 goto out;
 658
 659         write_lock_bh(&map->sock->sk->sk_callback_lock);
 660         map->saved_data_ready = map->sock->sk->sk_data_ready;
 661         map->sock->sk->sk_user_data = map;
 662         map->sock->sk->sk_data_ready = pvcalls_pass_sk_data_ready;
 663         write_unlock_bh(&map->sock->sk->sk_callback_lock);
 664
 665 out:
 666         if (ret) {
 667                 if (map && map->sock)
 668                         sock_release(map->sock);
 669                 if (map && map->wq)
 670                         destroy_workqueue(map->wq);
 671                 kfree(map);
 672         }
 673         rsp = RING_GET_RESPONSE(&fedata->ring, fedata->ring.rsp_prod_pvt++);
 674         rsp->req_id = req->req_id;
 675         rsp->cmd = req->cmd;
 676         rsp->u.bind.id = req->u.bind.id;
 677         rsp->ret = ret;
 678         return 0;
 679 }
 680
 681 static int pvcalls_back_listen(struct xenbus_device *dev,
 682                                struct xen_pvcalls_request *req)
 683 {
 684         struct pvcalls_fedata *fedata;
 685         int ret = -EINVAL;
 686         struct sockpass_mapping *map;
 687         struct xen_pvcalls_response *rsp;
 688
 689         fedata = dev_get_drvdata(&dev->dev);
 690
 691         down(&fedata->socket_lock);
 692         map = radix_tree_lookup(&fedata->socketpass_mappings, req->u.listen.id);
 693         up(&fedata->socket_lock);
 694         if (map == NULL)
 695                 goto out;
 696
 697         ret = inet_listen(map->sock, req->u.listen.backlog);
 698
 699 out:
 700         rsp = RING_GET_RESPONSE(&fedata->ring, fedata->ring.rsp_prod_pvt++);
 701         rsp->req_id = req->req_id;
 702         rsp->cmd = req->cmd;
 703         rsp->u.listen.id = req->u.listen.id;
 704         rsp->ret = ret;
 705         return 0;
 706 }
 707
 708 static int pvcalls_back_accept(struct xenbus_device *dev,
 709                                struct xen_pvcalls_request *req)
 710 {
 711         struct pvcalls_fedata *fedata;
 712         struct sockpass_mapping *mappass;
 713         int ret = -EINVAL;
 714         struct xen_pvcalls_response *rsp;
 715         unsigned long flags;
 716
 717         fedata = dev_get_drvdata(&dev->dev);
 718
 719         down(&fedata->socket_lock);
 720         mappass = radix_tree_lookup(&fedata->socketpass_mappings,
 721                 req->u.accept.id);
 722         up(&fedata->socket_lock);
 723         if (mappass == NULL)
 724                 goto out_error;
 725
 726         /*
 727          * Limitation of the current implementation: only support one
 728          * concurrent accept or poll call on one socket.
 729          */
 730         spin_lock_irqsave(&mappass->copy_lock, flags);
 731         if (mappass->reqcopy.cmd != 0) {
 732                 spin_unlock_irqrestore(&mappass->copy_lock, flags);
 733                 ret = -EINTR;
 734                 goto out_error;
 735         }
 736
 737         mappass->reqcopy = *req;
 738         spin_unlock_irqrestore(&mappass->copy_lock, flags);
 739         queue_work(mappass->wq, &mappass->register_work);
 740
 741         /* Tell the caller we don't need to send back a notification yet */
 742         return -1;
 743
 744 out_error:
 745         rsp = RING_GET_RESPONSE(&fedata->ring, fedata->ring.rsp_prod_pvt++);
 746         rsp->req_id = req->req_id;
 747         rsp->cmd = req->cmd;
 748         rsp->u.accept.id = req->u.accept.id;
 749         rsp->ret = ret;
 750         return 0;
 751 }
 752
 753 static int pvcalls_back_poll(struct xenbus_device *dev,
 754                              struct xen_pvcalls_request *req)
 755 {
 756         struct pvcalls_fedata *fedata;
 757         struct sockpass_mapping *mappass;
 758         struct xen_pvcalls_response *rsp;
 759         struct inet_connection_sock *icsk;
 760         struct request_sock_queue *queue;
 761         unsigned long flags;
 762         int ret;
 763         bool data;
 764
 765         fedata = dev_get_drvdata(&dev->dev);
 766
 767         down(&fedata->socket_lock);
 768         mappass = radix_tree_lookup(&fedata->socketpass_mappings,
 769                                     req->u.poll.id);
 770         up(&fedata->socket_lock);
 771         if (mappass == NULL)
 772                 return -EINVAL;
 773
 774         /*
 775          * Limitation of the current implementation: only support one
 776          * concurrent accept or poll call on one socket.
 777          */
 778         spin_lock_irqsave(&mappass->copy_lock, flags);
 779         if (mappass->reqcopy.cmd != 0) {
 780                 ret = -EINTR;
 781                 goto out;
 782         }
 783
 784         mappass->reqcopy = *req;
 785         icsk = inet_csk(mappass->sock->sk);
 786         queue = &icsk->icsk_accept_queue;
 787         data = READ_ONCE(queue->rskq_accept_head) != NULL;
 788         if (data) {
 789                 mappass->reqcopy.cmd = 0;
 790                 ret = 0;
 791                 goto out;
 792         }
 793         spin_unlock_irqrestore(&mappass->copy_lock, flags);
 794
 795         /* Tell the caller we don't need to send back a notification yet */
 796         return -1;
 797
 798 out:
 799         spin_unlock_irqrestore(&mappass->copy_lock, flags);
 800
 801         rsp = RING_GET_RESPONSE(&fedata->ring, fedata->ring.rsp_prod_pvt++);
 802         rsp->req_id = req->req_id;
 803         rsp->cmd = req->cmd;
 804         rsp->u.poll.id = req->u.poll.id;
 805         rsp->ret = ret;
 806         return 0;
 807 }
 808
 809 static int pvcalls_back_handle_cmd(struct xenbus_device *dev,
 810                                    struct xen_pvcalls_request *req)
 811 {
 812         int ret = 0;
 813
 814         switch (req->cmd) {
 815         case PVCALLS_SOCKET:
 816                 ret = pvcalls_back_socket(dev, req);
 817                 break;
 818         case PVCALLS_CONNECT:
 819                 ret = pvcalls_back_connect(dev, req);
 820                 break;
 821         case PVCALLS_RELEASE:
 822                 ret = pvcalls_back_release(dev, req);
 823                 break;
 824         case PVCALLS_BIND:
 825                 ret = pvcalls_back_bind(dev, req);
 826                 break;
 827         case PVCALLS_LISTEN:
 828                 ret = pvcalls_back_listen(dev, req);
 829                 break;
 830         case PVCALLS_ACCEPT:
 831                 ret = pvcalls_back_accept(dev, req);
 832                 break;
 833         case PVCALLS_POLL:
 834                 ret = pvcalls_back_poll(dev, req);
 835                 break;
 836         default:
 837         {
 838                 struct pvcalls_fedata *fedata;
 839                 struct xen_pvcalls_response *rsp;
 840
 841                 fedata = dev_get_drvdata(&dev->dev);
 842                 rsp = RING_GET_RESPONSE(
 843                                 &fedata->ring, fedata->ring.rsp_prod_pvt++);
 844                 rsp->req_id = req->req_id;
 845                 rsp->cmd = req->cmd;
 846                 rsp->ret = -ENOTSUPP;
 847                 break;
 848         }
 849         }
 850         return ret;
 851 }
 852
 853 static void pvcalls_back_work(struct pvcalls_fedata *fedata)
 854 {
 855         int notify, notify_all = 0, more = 1;
 856         struct xen_pvcalls_request req;
 857         struct xenbus_device *dev = fedata->dev;
 858
 859         while (more) {
 860                 while (RING_HAS_UNCONSUMED_REQUESTS(&fedata->ring)) {
 861                         RING_COPY_REQUEST(&fedata->ring,
 862                                           fedata->ring.req_cons++,
 863                                           &req);
 864
 865                         if (!pvcalls_back_handle_cmd(dev, &req)) {
 866                                 RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(
 867                                         &fedata->ring, notify);
 868                                 notify_all += notify;
 869                         }
 870                 }
 871
 872                 if (notify_all) {
 873                         notify_remote_via_irq(fedata->irq);
 874                         notify_all = 0;
 875                 }
 876
 877                 RING_FINAL_CHECK_FOR_REQUESTS(&fedata->ring, more);
 878         }
 879 }
 880
 881 static irqreturn_t pvcalls_back_event(int irq, void *dev_id)
 882 {
 883         struct xenbus_device *dev = dev_id;
 884         struct pvcalls_fedata *fedata = NULL;
 885         unsigned int eoi_flags = XEN_EOI_FLAG_SPURIOUS;
 886
 887         if (dev) {
 888                 fedata = dev_get_drvdata(&dev->dev);
 889                 if (fedata) {
 890                         pvcalls_back_work(fedata);
 891                         eoi_flags = 0;
 892                 }
 893         }
 894
 895         xen_irq_lateeoi(irq, eoi_flags);
 896
 897         return IRQ_HANDLED;
 898 }
 899
 900 static irqreturn_t pvcalls_back_conn_event(int irq, void *sock_map)
 901 {
 902         struct sock_mapping *map = sock_map;
 903         struct pvcalls_ioworker *iow;
 904
 905         if (map == NULL || map->sock == NULL || map->sock->sk == NULL ||
 906                 map->sock->sk->sk_user_data != map) {
 907                 xen_irq_lateeoi(irq, 0);
 908                 return IRQ_HANDLED;
 909         }
 910
 911         iow = &map->ioworker;
 912
 913         atomic_inc(&map->write);
 914         atomic_inc(&map->eoi);
 915         atomic_inc(&map->io);
 916         queue_work(iow->wq, &iow->register_work);
 917
 918         return IRQ_HANDLED;
 919 }
 920
 921 static int backend_connect(struct xenbus_device *dev)
 922 {
 923         int err;
 924         evtchn_port_t evtchn;
 925         grant_ref_t ring_ref;
 926         struct pvcalls_fedata *fedata = NULL;
 927
 928         fedata = kzalloc(sizeof(struct pvcalls_fedata), GFP_KERNEL);
 929         if (!fedata)
 930                 return -ENOMEM;
 931
 932         fedata->irq = -1;
 933         err = xenbus_scanf(XBT_NIL, dev->otherend, "port", "%u",
 934                            &evtchn);
 935         if (err != 1) {
 936                 err = -EINVAL;
 937                 xenbus_dev_fatal(dev, err, "reading %s/event-channel",
 938                                  dev->otherend);
 939                 goto error;
 940         }
 941
 942         err = xenbus_scanf(XBT_NIL, dev->otherend, "ring-ref", "%u", &ring_ref);
 943         if (err != 1) {
 944                 err = -EINVAL;
 945                 xenbus_dev_fatal(dev, err, "reading %s/ring-ref",
 946                                  dev->otherend);
 947                 goto error;
 948         }
 949
 950         err = bind_interdomain_evtchn_to_irq_lateeoi(dev->otherend_id, evtchn);
 951         if (err < 0)
 952                 goto error;
 953         fedata->irq = err;
 954
 955         err = request_threaded_irq(fedata->irq, NULL, pvcalls_back_event,
 956                                    IRQF_ONESHOT, "pvcalls-back", dev);
 957         if (err < 0)
 958                 goto error;
 959
 960         err = xenbus_map_ring_valloc(dev, &ring_ref, 1,
 961                                      (void **)&fedata->sring);
 962         if (err < 0)
 963                 goto error;
 964
 965         BACK_RING_INIT(&fedata->ring, fedata->sring, XEN_PAGE_SIZE * 1);
 966         fedata->dev = dev;
 967
 968         INIT_LIST_HEAD(&fedata->socket_mappings);
 969         INIT_RADIX_TREE(&fedata->socketpass_mappings, GFP_KERNEL);
 970         sema_init(&fedata->socket_lock, 1);
 971         dev_set_drvdata(&dev->dev, fedata);
 972
 973         down(&pvcalls_back_global.frontends_lock);
 974         list_add_tail(&fedata->list, &pvcalls_back_global.frontends);
 975         up(&pvcalls_back_global.frontends_lock);
 976
 977         return 0;
 978
 979  error:
 980         if (fedata->irq >= 0)
 981                 unbind_from_irqhandler(fedata->irq, dev);
 982         if (fedata->sring != NULL)
 983                 xenbus_unmap_ring_vfree(dev, fedata->sring);
 984         kfree(fedata);
 985         return err;
 986 }
 987
 988 static int backend_disconnect(struct xenbus_device *dev)
 989 {
 990         struct pvcalls_fedata *fedata;
 991         struct sock_mapping *map, *n;
 992         struct sockpass_mapping *mappass;
 993         struct radix_tree_iter iter;
 994         void **slot;
 995
 996
 997         fedata = dev_get_drvdata(&dev->dev);
 998
 999         down(&fedata->socket_lock);
1000         list_for_each_entry_safe(map, n, &fedata->socket_mappings, list) {
1001                 list_del(&map->list);
1002                 pvcalls_back_release_active(dev, fedata, map);
1003         }
1004
1005         radix_tree_for_each_slot(slot, &fedata->socketpass_mappings, &iter, 0) {
1006                 mappass = radix_tree_deref_slot(slot);
1007                 if (!mappass)
1008                         continue;
1009                 if (radix_tree_exception(mappass)) {
1010                         if (radix_tree_deref_retry(mappass))
1011                                 slot = radix_tree_iter_retry(&iter);
1012                 } else {
1013                         radix_tree_delete(&fedata->socketpass_mappings,
1014                                           mappass->id);
1015                         pvcalls_back_release_passive(dev, fedata, mappass);
1016                 }
1017         }
1018         up(&fedata->socket_lock);
1019
1020         unbind_from_irqhandler(fedata->irq, dev);
1021         xenbus_unmap_ring_vfree(dev, fedata->sring);
1022
1023         list_del(&fedata->list);
1024         kfree(fedata);
1025         dev_set_drvdata(&dev->dev, NULL);
1026
1027         return 0;
1028 }
1029
1030 static int pvcalls_back_probe(struct xenbus_device *dev,
1031                               const struct xenbus_device_id *id)
1032 {
1033         int err, abort;
1034         struct xenbus_transaction xbt;
1035
1036 again:
1037         abort = 1;
1038
1039         err = xenbus_transaction_start(&xbt);
1040         if (err) {
1041                 pr_warn("%s cannot create xenstore transaction\n", __func__);
1042                 return err;
1043         }
1044
1045         err = xenbus_printf(xbt, dev->nodename, "versions", "%s",
1046                             PVCALLS_VERSIONS);
1047         if (err) {
1048                 pr_warn("%s write out 'versions' failed\n", __func__);
1049                 goto abort;
1050         }
1051
1052         err = xenbus_printf(xbt, dev->nodename, "max-page-order", "%u",
1053                             MAX_RING_ORDER);
1054         if (err) {
1055                 pr_warn("%s write out 'max-page-order' failed\n", __func__);
1056                 goto abort;
1057         }
1058
1059         err = xenbus_printf(xbt, dev->nodename, "function-calls",
1060                             XENBUS_FUNCTIONS_CALLS);
1061         if (err) {
1062                 pr_warn("%s write out 'function-calls' failed\n", __func__);
1063                 goto abort;
1064         }
1065
1066         abort = 0;
1067 abort:
1068         err = xenbus_transaction_end(xbt, abort);
1069         if (err) {
1070                 if (err == -EAGAIN && !abort)
1071                         goto again;
1072                 pr_warn("%s cannot complete xenstore transaction\n", __func__);
1073                 return err;
1074         }
1075
1076         if (abort)
1077                 return -EFAULT;
1078
1079         xenbus_switch_state(dev, XenbusStateInitWait);
1080
1081         return 0;
1082 }
1083
1084 static void set_backend_state(struct xenbus_device *dev,
1085                               enum xenbus_state state)
1086 {
1087         while (dev->state != state) {
1088                 switch (dev->state) {
1089                 case XenbusStateClosed:
1090                         switch (state) {
1091                         case XenbusStateInitWait:
1092                         case XenbusStateConnected:
1093                                 xenbus_switch_state(dev, XenbusStateInitWait);
1094                                 break;
1095                         case XenbusStateClosing:
1096                                 xenbus_switch_state(dev, XenbusStateClosing);
1097                                 break;
1098                         default:
1099                                 WARN_ON(1);
1100                         }
1101                         break;
1102                 case XenbusStateInitWait:
1103                 case XenbusStateInitialised:
1104                         switch (state) {
1105                         case XenbusStateConnected:
1106                                 if (backend_connect(dev))
1107                                         return;
1108                                 xenbus_switch_state(dev, XenbusStateConnected);
1109                                 break;
1110                         case XenbusStateClosing:
1111                         case XenbusStateClosed:
1112                                 xenbus_switch_state(dev, XenbusStateClosing);
1113                                 break;
1114                         default:
1115                                 WARN_ON(1);
1116                         }
1117                         break;
1118                 case XenbusStateConnected:
1119                         switch (state) {
1120                         case XenbusStateInitWait:
1121                         case XenbusStateClosing:
1122                         case XenbusStateClosed:
1123                                 down(&pvcalls_back_global.frontends_lock);
1124                                 backend_disconnect(dev);
1125                                 up(&pvcalls_back_global.frontends_lock);
1126                                 xenbus_switch_state(dev, XenbusStateClosing);
1127                                 break;
1128                         default:
1129                                 WARN_ON(1);
1130                         }
1131                         break;
1132                 case XenbusStateClosing:
1133                         switch (state) {
1134                         case XenbusStateInitWait:
1135                         case XenbusStateConnected:
1136                         case XenbusStateClosed:
1137                                 xenbus_switch_state(dev, XenbusStateClosed);
1138                                 break;
1139                         default:
1140                                 WARN_ON(1);
1141                         }
1142                         break;
1143                 default:
1144                         WARN_ON(1);
1145                 }
1146         }
1147 }
1148
1149 static void pvcalls_back_changed(struct xenbus_device *dev,
1150                                  enum xenbus_state frontend_state)
1151 {
1152         switch (frontend_state) {
1153         case XenbusStateInitialising:
1154                 set_backend_state(dev, XenbusStateInitWait);
1155                 break;
1156
1157         case XenbusStateInitialised:
1158         case XenbusStateConnected:
1159                 set_backend_state(dev, XenbusStateConnected);
1160                 break;
1161
1162         case XenbusStateClosing:
1163                 set_backend_state(dev, XenbusStateClosing);
1164                 break;
1165
1166         case XenbusStateClosed:
1167                 set_backend_state(dev, XenbusStateClosed);
1168                 if (xenbus_dev_is_online(dev))
1169                         break;
1170                 device_unregister(&dev->dev);
1171                 break;
1172         case XenbusStateUnknown:
1173                 set_backend_state(dev, XenbusStateClosed);
1174                 device_unregister(&dev->dev);
1175                 break;
1176
1177         default:
1178                 xenbus_dev_fatal(dev, -EINVAL, "saw state %d at frontend",
1179                                  frontend_state);
1180                 break;
1181         }
1182 }
1183
1184 static int pvcalls_back_remove(struct xenbus_device *dev)
1185 {
1186         return 0;
1187 }
1188
1189 static int pvcalls_back_uevent(struct xenbus_device *xdev,
1190                                struct kobj_uevent_env *env)
1191 {
1192         return 0;
1193 }
1194
1195 static const struct xenbus_device_id pvcalls_back_ids[] = {
1196         { "pvcalls" },
1197         { "" }
1198 };
1199
1200 static struct xenbus_driver pvcalls_back_driver = {
1201         .ids = pvcalls_back_ids,
1202         .probe = pvcalls_back_probe,
1203         .remove = pvcalls_back_remove,
1204         .uevent = pvcalls_back_uevent,
1205         .otherend_changed = pvcalls_back_changed,
1206 };
1207
1208 static int __init pvcalls_back_init(void)
1209 {
1210         int ret;
1211
1212         if (!xen_domain())
1213                 return -ENODEV;
1214
1215         ret = xenbus_register_backend(&pvcalls_back_driver);
1216         if (ret < 0)
1217                 return ret;
1218
1219         sema_init(&pvcalls_back_global.frontends_lock, 1);
1220         INIT_LIST_HEAD(&pvcalls_back_global.frontends);
1221         return 0;
1222 }
1223 module_init(pvcalls_back_init);
1224
1225 static void __exit pvcalls_back_fin(void)
1226 {
1227         struct pvcalls_fedata *fedata, *nfedata;
1228
1229         down(&pvcalls_back_global.frontends_lock);
1230         list_for_each_entry_safe(fedata, nfedata,
1231                                  &pvcalls_back_global.frontends, list) {
1232                 backend_disconnect(fedata->dev);
1233         }
1234         up(&pvcalls_back_global.frontends_lock);
1235
1236         xenbus_unregister_driver(&pvcalls_back_driver);
1237 }
1238
1239 module_exit(pvcalls_back_fin);
1240
1241 MODULE_DESCRIPTION("Xen PV Calls backend driver");
1242 MODULE_AUTHOR("Stefano Stabellini <sstabellini@kernel.org>");
1243 MODULE_LICENSE("GPL");