linux/drivers/xen/pvcalls-back.c
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   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
  27static 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 */
  37struct 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
  48struct pvcalls_ioworker {
  49        struct work_struct register_work;
  50        struct workqueue_struct *wq;
  51};
  52
  53struct 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
  74struct 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
  86static irqreturn_t pvcalls_back_conn_event(int irq, void *sock_map);
  87static int pvcalls_back_release_active(struct xenbus_device *dev,
  88                                       struct pvcalls_fedata *fedata,
  89                                       struct sock_mapping *map);
  90
  91static 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
 167static 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
 228static 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
 259static 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
 287static 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
 298static 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
 312static 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;
 378out:
 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
 386static 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
 422out:
 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
 432static 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
 457static 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
 475static 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
 504out:
 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
 513static 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
 571out_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
 584static 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
 617static 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
 666out:
 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
 682static 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
 700out:
 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
 709static 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
 745out_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
 754static 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
 799out:
 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
 810static 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
 854static 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
 882static 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
 901static 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
 922static 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
 989static 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
1031static 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
1037again:
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;
1068abort:
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
1085static 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
1150static 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
1185static int pvcalls_back_remove(struct xenbus_device *dev)
1186{
1187        return 0;
1188}
1189
1190static int pvcalls_back_uevent(struct xenbus_device *xdev,
1191                               struct kobj_uevent_env *env)
1192{
1193        return 0;
1194}
1195
1196static const struct xenbus_device_id pvcalls_back_ids[] = {
1197        { "pvcalls" },
1198        { "" }
1199};
1200
1201static 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
1209static 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}
1224module_init(pvcalls_back_init);
1225
1226static 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
1240module_exit(pvcalls_back_fin);
1241
1242MODULE_DESCRIPTION("Xen PV Calls backend driver");
1243MODULE_AUTHOR("Stefano Stabellini <sstabellini@kernel.org>");
1244MODULE_LICENSE("GPL");
1245
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