drivers/net/xen-netback/xenbus.c

   1 /*
   2  * Xenbus code for netif backend
   3  *
   4  * Copyright (C) 2005 Rusty Russell <rusty@rustcorp.com.au>
   5  * Copyright (C) 2005 XenSource Ltd
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 2 of the License, or
  10  * (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; if not, see <http://www.gnu.org/licenses/>.
  19 */
  20
  21 #include "common.h"
  22 #include <linux/vmalloc.h>
  23 #include <linux/rtnetlink.h>
  24
  25 struct backend_info {
  26         struct xenbus_device *dev;
  27         struct xenvif *vif;
  28
  29         /* This is the state that will be reflected in xenstore when any
  30          * active hotplug script completes.
  31          */
  32         enum xenbus_state state;
  33
  34         enum xenbus_state frontend_state;
  35         struct xenbus_watch hotplug_status_watch;
  36         u8 have_hotplug_status_watch:1;
  37
  38         const char *hotplug_script;
  39 };
  40
  41 static int connect_rings(struct backend_info *be, struct xenvif_queue *queue);
  42 static void connect(struct backend_info *be);
  43 static int read_xenbus_vif_flags(struct backend_info *be);
  44 static int backend_create_xenvif(struct backend_info *be);
  45 static void unregister_hotplug_status_watch(struct backend_info *be);
  46 static void xen_unregister_watchers(struct xenvif *vif);
  47 static void set_backend_state(struct backend_info *be,
  48                               enum xenbus_state state);
  49
  50 #ifdef CONFIG_DEBUG_FS
  51 struct dentry *xen_netback_dbg_root = NULL;
  52
  53 static int xenvif_read_io_ring(struct seq_file *m, void *v)
  54 {
  55         struct xenvif_queue *queue = m->private;
  56         struct xen_netif_tx_back_ring *tx_ring = &queue->tx;
  57         struct xen_netif_rx_back_ring *rx_ring = &queue->rx;
  58         struct netdev_queue *dev_queue;
  59
  60         if (tx_ring->sring) {
  61                 struct xen_netif_tx_sring *sring = tx_ring->sring;
  62
  63                 seq_printf(m, "Queue %d\nTX: nr_ents %u\n", queue->id,
  64                            tx_ring->nr_ents);
  65                 seq_printf(m, "req prod %u (%d) cons %u (%d) event %u (%d)\n",
  66                            sring->req_prod,
  67                            sring->req_prod - sring->rsp_prod,
  68                            tx_ring->req_cons,
  69                            tx_ring->req_cons - sring->rsp_prod,
  70                            sring->req_event,
  71                            sring->req_event - sring->rsp_prod);
  72                 seq_printf(m, "rsp prod %u (base) pvt %u (%d) event %u (%d)\n",
  73                            sring->rsp_prod,
  74                            tx_ring->rsp_prod_pvt,
  75                            tx_ring->rsp_prod_pvt - sring->rsp_prod,
  76                            sring->rsp_event,
  77                            sring->rsp_event - sring->rsp_prod);
  78                 seq_printf(m, "pending prod %u pending cons %u nr_pending_reqs %u\n",
  79                            queue->pending_prod,
  80                            queue->pending_cons,
  81                            nr_pending_reqs(queue));
  82                 seq_printf(m, "dealloc prod %u dealloc cons %u dealloc_queue %u\n\n",
  83                            queue->dealloc_prod,
  84                            queue->dealloc_cons,
  85                            queue->dealloc_prod - queue->dealloc_cons);
  86         }
  87
  88         if (rx_ring->sring) {
  89                 struct xen_netif_rx_sring *sring = rx_ring->sring;
  90
  91                 seq_printf(m, "RX: nr_ents %u\n", rx_ring->nr_ents);
  92                 seq_printf(m, "req prod %u (%d) cons %u (%d) event %u (%d)\n",
  93                            sring->req_prod,
  94                            sring->req_prod - sring->rsp_prod,
  95                            rx_ring->req_cons,
  96                            rx_ring->req_cons - sring->rsp_prod,
  97                            sring->req_event,
  98                            sring->req_event - sring->rsp_prod);
  99                 seq_printf(m, "rsp prod %u (base) pvt %u (%d) event %u (%d)\n\n",
 100                            sring->rsp_prod,
 101                            rx_ring->rsp_prod_pvt,
 102                            rx_ring->rsp_prod_pvt - sring->rsp_prod,
 103                            sring->rsp_event,
 104                            sring->rsp_event - sring->rsp_prod);
 105         }
 106
 107         seq_printf(m, "NAPI state: %lx NAPI weight: %d TX queue len %u\n"
 108                    "Credit timer_pending: %d, credit: %lu, usec: %lu\n"
 109                    "remaining: %lu, expires: %lu, now: %lu\n",
 110                    queue->napi.state, queue->napi.weight,
 111                    skb_queue_len(&queue->tx_queue),
 112                    timer_pending(&queue->credit_timeout),
 113                    queue->credit_bytes,
 114                    queue->credit_usec,
 115                    queue->remaining_credit,
 116                    queue->credit_timeout.expires,
 117                    jiffies);
 118
 119         dev_queue = netdev_get_tx_queue(queue->vif->dev, queue->id);
 120
 121         seq_printf(m, "\nRx internal queue: len %u max %u pkts %u %s\n",
 122                    queue->rx_queue_len, queue->rx_queue_max,
 123                    skb_queue_len(&queue->rx_queue),
 124                    netif_tx_queue_stopped(dev_queue) ? "stopped" : "running");
 125
 126         return 0;
 127 }
 128
 129 #define XENVIF_KICK_STR "kick"
 130 #define BUFFER_SIZE     32
 131
 132 static ssize_t
 133 xenvif_write_io_ring(struct file *filp, const char __user *buf, size_t count,
 134                      loff_t *ppos)
 135 {
 136         struct xenvif_queue *queue =
 137                 ((struct seq_file *)filp->private_data)->private;
 138         int len;
 139         char write[BUFFER_SIZE];
 140
 141         /* don't allow partial writes and check the length */
 142         if (*ppos != 0)
 143                 return 0;
 144         if (count >= sizeof(write))
 145                 return -ENOSPC;
 146
 147         len = simple_write_to_buffer(write,
 148                                      sizeof(write) - 1,
 149                                      ppos,
 150                                      buf,
 151                                      count);
 152         if (len < 0)
 153                 return len;
 154
 155         write[len] = '\0';
 156
 157         if (!strncmp(write, XENVIF_KICK_STR, sizeof(XENVIF_KICK_STR) - 1))
 158                 xenvif_interrupt(0, (void *)queue);
 159         else {
 160                 pr_warn("Unknown command to io_ring_q%d. Available: kick\n",
 161                         queue->id);
 162                 count = -EINVAL;
 163         }
 164         return count;
 165 }
 166
 167 static int xenvif_dump_open(struct inode *inode, struct file *filp)
 168 {
 169         int ret;
 170         void *queue = NULL;
 171
 172         if (inode->i_private)
 173                 queue = inode->i_private;
 174         ret = single_open(filp, xenvif_read_io_ring, queue);
 175         filp->f_mode |= FMODE_PWRITE;
 176         return ret;
 177 }
 178
 179 static const struct file_operations xenvif_dbg_io_ring_ops_fops = {
 180         .owner = THIS_MODULE,
 181         .open = xenvif_dump_open,
 182         .read = seq_read,
 183         .llseek = seq_lseek,
 184         .release = single_release,
 185         .write = xenvif_write_io_ring,
 186 };
 187
 188 static void xenvif_debugfs_addif(struct xenvif *vif)
 189 {
 190         struct dentry *pfile;
 191         int i;
 192
 193         if (IS_ERR_OR_NULL(xen_netback_dbg_root))
 194                 return;
 195
 196         vif->xenvif_dbg_root = debugfs_create_dir(vif->dev->name,
 197                                                   xen_netback_dbg_root);
 198         if (!IS_ERR_OR_NULL(vif->xenvif_dbg_root)) {
 199                 for (i = 0; i < vif->num_queues; ++i) {
 200                         char filename[sizeof("io_ring_q") + 4];
 201
 202                         snprintf(filename, sizeof(filename), "io_ring_q%d", i);
 203                         pfile = debugfs_create_file(filename,
 204                                                     S_IRUSR | S_IWUSR,
 205                                                     vif->xenvif_dbg_root,
 206                                                     &vif->queues[i],
 207                                                     &xenvif_dbg_io_ring_ops_fops);
 208                         if (IS_ERR_OR_NULL(pfile))
 209                                 pr_warn("Creation of io_ring file returned %ld!\n",
 210                                         PTR_ERR(pfile));
 211                 }
 212         } else
 213                 netdev_warn(vif->dev,
 214                             "Creation of vif debugfs dir returned %ld!\n",
 215                             PTR_ERR(vif->xenvif_dbg_root));
 216 }
 217
 218 static void xenvif_debugfs_delif(struct xenvif *vif)
 219 {
 220         if (IS_ERR_OR_NULL(xen_netback_dbg_root))
 221                 return;
 222
 223         if (!IS_ERR_OR_NULL(vif->xenvif_dbg_root))
 224                 debugfs_remove_recursive(vif->xenvif_dbg_root);
 225         vif->xenvif_dbg_root = NULL;
 226 }
 227 #endif /* CONFIG_DEBUG_FS */
 228
 229 static int netback_remove(struct xenbus_device *dev)
 230 {
 231         struct backend_info *be = dev_get_drvdata(&dev->dev);
 232
 233         set_backend_state(be, XenbusStateClosed);
 234
 235         unregister_hotplug_status_watch(be);
 236         if (be->vif) {
 237                 kobject_uevent(&dev->dev.kobj, KOBJ_OFFLINE);
 238                 xen_unregister_watchers(be->vif);
 239                 xenbus_rm(XBT_NIL, dev->nodename, "hotplug-status");
 240                 xenvif_free(be->vif);
 241                 be->vif = NULL;
 242         }
 243         kfree(be->hotplug_script);
 244         kfree(be);
 245         dev_set_drvdata(&dev->dev, NULL);
 246         return 0;
 247 }
 248
 249
 250 /**
 251  * Entry point to this code when a new device is created.  Allocate the basic
 252  * structures and switch to InitWait.
 253  */
 254 static int netback_probe(struct xenbus_device *dev,
 255                          const struct xenbus_device_id *id)
 256 {
 257         const char *message;
 258         struct xenbus_transaction xbt;
 259         int err;
 260         int sg;
 261         const char *script;
 262         struct backend_info *be = kzalloc(sizeof(struct backend_info),
 263                                           GFP_KERNEL);
 264         if (!be) {
 265                 xenbus_dev_fatal(dev, -ENOMEM,
 266                                  "allocating backend structure");
 267                 return -ENOMEM;
 268         }
 269
 270         be->dev = dev;
 271         dev_set_drvdata(&dev->dev, be);
 272
 273         sg = 1;
 274
 275         do {
 276                 err = xenbus_transaction_start(&xbt);
 277                 if (err) {
 278                         xenbus_dev_fatal(dev, err, "starting transaction");
 279                         goto fail;
 280                 }
 281
 282                 err = xenbus_printf(xbt, dev->nodename, "feature-sg", "%d", sg);
 283                 if (err) {
 284                         message = "writing feature-sg";
 285                         goto abort_transaction;
 286                 }
 287
 288                 err = xenbus_printf(xbt, dev->nodename, "feature-gso-tcpv4",
 289                                     "%d", sg);
 290                 if (err) {
 291                         message = "writing feature-gso-tcpv4";
 292                         goto abort_transaction;
 293                 }
 294
 295                 err = xenbus_printf(xbt, dev->nodename, "feature-gso-tcpv6",
 296                                     "%d", sg);
 297                 if (err) {
 298                         message = "writing feature-gso-tcpv6";
 299                         goto abort_transaction;
 300                 }
 301
 302                 /* We support partial checksum setup for IPv6 packets */
 303                 err = xenbus_printf(xbt, dev->nodename,
 304                                     "feature-ipv6-csum-offload",
 305                                     "%d", 1);
 306                 if (err) {
 307                         message = "writing feature-ipv6-csum-offload";
 308                         goto abort_transaction;
 309                 }
 310
 311                 /* We support rx-copy path. */
 312                 err = xenbus_printf(xbt, dev->nodename,
 313                                     "feature-rx-copy", "%d", 1);
 314                 if (err) {
 315                         message = "writing feature-rx-copy";
 316                         goto abort_transaction;
 317                 }
 318
 319                 /*
 320                  * We don't support rx-flip path (except old guests who don't
 321                  * grok this feature flag).
 322                  */
 323                 err = xenbus_printf(xbt, dev->nodename,
 324                                     "feature-rx-flip", "%d", 0);
 325                 if (err) {
 326                         message = "writing feature-rx-flip";
 327                         goto abort_transaction;
 328                 }
 329
 330                 /* We support multicast-control. */
 331                 err = xenbus_printf(xbt, dev->nodename,
 332                                     "feature-multicast-control", "%d", 1);
 333                 if (err) {
 334                         message = "writing feature-multicast-control";
 335                         goto abort_transaction;
 336                 }
 337
 338                 err = xenbus_transaction_end(xbt, 0);
 339         } while (err == -EAGAIN);
 340
 341         if (err) {
 342                 xenbus_dev_fatal(dev, err, "completing transaction");
 343                 goto fail;
 344         }
 345
 346         /*
 347          * Split event channels support, this is optional so it is not
 348          * put inside the above loop.
 349          */
 350         err = xenbus_printf(XBT_NIL, dev->nodename,
 351                             "feature-split-event-channels",
 352                             "%u", separate_tx_rx_irq);
 353         if (err)
 354                 pr_debug("Error writing feature-split-event-channels\n");
 355
 356         /* Multi-queue support: This is an optional feature. */
 357         err = xenbus_printf(XBT_NIL, dev->nodename,
 358                             "multi-queue-max-queues", "%u", xenvif_max_queues);
 359         if (err)
 360                 pr_debug("Error writing multi-queue-max-queues\n");
 361
 362         script = xenbus_read(XBT_NIL, dev->nodename, "script", NULL);
 363         if (IS_ERR(script)) {
 364                 err = PTR_ERR(script);
 365                 xenbus_dev_fatal(dev, err, "reading script");
 366                 goto fail;
 367         }
 368
 369         be->hotplug_script = script;
 370
 371         err = xenbus_switch_state(dev, XenbusStateInitWait);
 372         if (err)
 373                 goto fail;
 374
 375         be->state = XenbusStateInitWait;
 376
 377         /* This kicks hotplug scripts, so do it immediately. */
 378         err = backend_create_xenvif(be);
 379         if (err)
 380                 goto fail;
 381
 382         return 0;
 383
 384 abort_transaction:
 385         xenbus_transaction_end(xbt, 1);
 386         xenbus_dev_fatal(dev, err, "%s", message);
 387 fail:
 388         pr_debug("failed\n");
 389         netback_remove(dev);
 390         return err;
 391 }
 392
 393
 394 /*
 395  * Handle the creation of the hotplug script environment.  We add the script
 396  * and vif variables to the environment, for the benefit of the vif-* hotplug
 397  * scripts.
 398  */
 399 static int netback_uevent(struct xenbus_device *xdev,
 400                           struct kobj_uevent_env *env)
 401 {
 402         struct backend_info *be = dev_get_drvdata(&xdev->dev);
 403
 404         if (!be)
 405                 return 0;
 406
 407         if (add_uevent_var(env, "script=%s", be->hotplug_script))
 408                 return -ENOMEM;
 409
 410         if (!be->vif)
 411                 return 0;
 412
 413         return add_uevent_var(env, "vif=%s", be->vif->dev->name);
 414 }
 415
 416
 417 static int backend_create_xenvif(struct backend_info *be)
 418 {
 419         int err;
 420         long handle;
 421         struct xenbus_device *dev = be->dev;
 422         struct xenvif *vif;
 423
 424         if (be->vif != NULL)
 425                 return 0;
 426
 427         err = xenbus_scanf(XBT_NIL, dev->nodename, "handle", "%li", &handle);
 428         if (err != 1) {
 429                 xenbus_dev_fatal(dev, err, "reading handle");
 430                 return (err < 0) ? err : -EINVAL;
 431         }
 432
 433         vif = xenvif_alloc(&dev->dev, dev->otherend_id, handle);
 434         if (IS_ERR(vif)) {
 435                 err = PTR_ERR(vif);
 436                 xenbus_dev_fatal(dev, err, "creating interface");
 437                 return err;
 438         }
 439         be->vif = vif;
 440
 441         kobject_uevent(&dev->dev.kobj, KOBJ_ONLINE);
 442         return 0;
 443 }
 444
 445 static void backend_disconnect(struct backend_info *be)
 446 {
 447         if (be->vif) {
 448                 xen_unregister_watchers(be->vif);
 449 #ifdef CONFIG_DEBUG_FS
 450                 xenvif_debugfs_delif(be->vif);
 451 #endif /* CONFIG_DEBUG_FS */
 452                 xenvif_disconnect(be->vif);
 453         }
 454 }
 455
 456 static void backend_connect(struct backend_info *be)
 457 {
 458         if (be->vif)
 459                 connect(be);
 460 }
 461
 462 static inline void backend_switch_state(struct backend_info *be,
 463                                         enum xenbus_state state)
 464 {
 465         struct xenbus_device *dev = be->dev;
 466
 467         pr_debug("%s -> %s\n", dev->nodename, xenbus_strstate(state));
 468         be->state = state;
 469
 470         /* If we are waiting for a hotplug script then defer the
 471          * actual xenbus state change.
 472          */
 473         if (!be->have_hotplug_status_watch)
 474                 xenbus_switch_state(dev, state);
 475 }
 476
 477 /* Handle backend state transitions:
 478  *
 479  * The backend state starts in InitWait and the following transitions are
 480  * allowed.
 481  *
 482  * InitWait -> Connected
 483  *
 484  *    ^    \         |
 485  *    |     \        |
 486  *    |      \       |
 487  *    |       \      |
 488  *    |        \     |
 489  *    |         \    |
 490  *    |          V   V
 491  *
 492  *  Closed  <-> Closing
 493  *
 494  * The state argument specifies the eventual state of the backend and the
 495  * function transitions to that state via the shortest path.
 496  */
 497 static void set_backend_state(struct backend_info *be,
 498                               enum xenbus_state state)
 499 {
 500         while (be->state != state) {
 501                 switch (be->state) {
 502                 case XenbusStateClosed:
 503                         switch (state) {
 504                         case XenbusStateInitWait:
 505                         case XenbusStateConnected:
 506                                 pr_info("%s: prepare for reconnect\n",
 507                                         be->dev->nodename);
 508                                 backend_switch_state(be, XenbusStateInitWait);
 509                                 break;
 510                         case XenbusStateClosing:
 511                                 backend_switch_state(be, XenbusStateClosing);
 512                                 break;
 513                         default:
 514                                 BUG();
 515                         }
 516                         break;
 517                 case XenbusStateInitWait:
 518                         switch (state) {
 519                         case XenbusStateConnected:
 520                                 backend_connect(be);
 521                                 backend_switch_state(be, XenbusStateConnected);
 522                                 break;
 523                         case XenbusStateClosing:
 524                         case XenbusStateClosed:
 525                                 backend_switch_state(be, XenbusStateClosing);
 526                                 break;
 527                         default:
 528                                 BUG();
 529                         }
 530                         break;
 531                 case XenbusStateConnected:
 532                         switch (state) {
 533                         case XenbusStateInitWait:
 534                         case XenbusStateClosing:
 535                         case XenbusStateClosed:
 536                                 backend_disconnect(be);
 537                                 backend_switch_state(be, XenbusStateClosing);
 538                                 break;
 539                         default:
 540                                 BUG();
 541                         }
 542                         break;
 543                 case XenbusStateClosing:
 544                         switch (state) {
 545                         case XenbusStateInitWait:
 546                         case XenbusStateConnected:
 547                         case XenbusStateClosed:
 548                                 backend_switch_state(be, XenbusStateClosed);
 549                                 break;
 550                         default:
 551                                 BUG();
 552                         }
 553                         break;
 554                 default:
 555                         BUG();
 556                 }
 557         }
 558 }
 559
 560 /**
 561  * Callback received when the frontend's state changes.
 562  */
 563 static void frontend_changed(struct xenbus_device *dev,
 564                              enum xenbus_state frontend_state)
 565 {
 566         struct backend_info *be = dev_get_drvdata(&dev->dev);
 567
 568         pr_debug("%s -> %s\n", dev->otherend, xenbus_strstate(frontend_state));
 569
 570         be->frontend_state = frontend_state;
 571
 572         switch (frontend_state) {
 573         case XenbusStateInitialising:
 574                 set_backend_state(be, XenbusStateInitWait);
 575                 break;
 576
 577         case XenbusStateInitialised:
 578                 break;
 579
 580         case XenbusStateConnected:
 581                 set_backend_state(be, XenbusStateConnected);
 582                 break;
 583
 584         case XenbusStateClosing:
 585                 set_backend_state(be, XenbusStateClosing);
 586                 break;
 587
 588         case XenbusStateClosed:
 589                 set_backend_state(be, XenbusStateClosed);
 590                 if (xenbus_dev_is_online(dev))
 591                         break;
 592                 /* fall through if not online */
 593         case XenbusStateUnknown:
 594                 set_backend_state(be, XenbusStateClosed);
 595                 device_unregister(&dev->dev);
 596                 break;
 597
 598         default:
 599                 xenbus_dev_fatal(dev, -EINVAL, "saw state %d at frontend",
 600                                  frontend_state);
 601                 break;
 602         }
 603 }
 604
 605
 606 static void xen_net_read_rate(struct xenbus_device *dev,
 607                               unsigned long *bytes, unsigned long *usec)
 608 {
 609         char *s, *e;
 610         unsigned long b, u;
 611         char *ratestr;
 612
 613         /* Default to unlimited bandwidth. */
 614         *bytes = ~0UL;
 615         *usec = 0;
 616
 617         ratestr = xenbus_read(XBT_NIL, dev->nodename, "rate", NULL);
 618         if (IS_ERR(ratestr))
 619                 return;
 620
 621         s = ratestr;
 622         b = simple_strtoul(s, &e, 10);
 623         if ((s == e) || (*e != ','))
 624                 goto fail;
 625
 626         s = e + 1;
 627         u = simple_strtoul(s, &e, 10);
 628         if ((s == e) || (*e != '\0'))
 629                 goto fail;
 630
 631         *bytes = b;
 632         *usec = u;
 633
 634         kfree(ratestr);
 635         return;
 636
 637  fail:
 638         pr_warn("Failed to parse network rate limit. Traffic unlimited.\n");
 639         kfree(ratestr);
 640 }
 641
 642 static int xen_net_read_mac(struct xenbus_device *dev, u8 mac[])
 643 {
 644         char *s, *e, *macstr;
 645         int i;
 646
 647         macstr = s = xenbus_read(XBT_NIL, dev->nodename, "mac", NULL);
 648         if (IS_ERR(macstr))
 649                 return PTR_ERR(macstr);
 650
 651         for (i = 0; i < ETH_ALEN; i++) {
 652                 mac[i] = simple_strtoul(s, &e, 16);
 653                 if ((s == e) || (*e != ((i == ETH_ALEN-1) ? '\0' : ':'))) {
 654                         kfree(macstr);
 655                         return -ENOENT;
 656                 }
 657                 s = e+1;
 658         }
 659
 660         kfree(macstr);
 661         return 0;
 662 }
 663
 664 static void xen_net_rate_changed(struct xenbus_watch *watch,
 665                                 const char **vec, unsigned int len)
 666 {
 667         struct xenvif *vif = container_of(watch, struct xenvif, credit_watch);
 668         struct xenbus_device *dev = xenvif_to_xenbus_device(vif);
 669         unsigned long   credit_bytes;
 670         unsigned long   credit_usec;
 671         unsigned int queue_index;
 672
 673         xen_net_read_rate(dev, &credit_bytes, &credit_usec);
 674         for (queue_index = 0; queue_index < vif->num_queues; queue_index++) {
 675                 struct xenvif_queue *queue = &vif->queues[queue_index];
 676
 677                 queue->credit_bytes = credit_bytes;
 678                 queue->credit_usec = credit_usec;
 679                 if (!mod_timer_pending(&queue->credit_timeout, jiffies) &&
 680                         queue->remaining_credit > queue->credit_bytes) {
 681                         queue->remaining_credit = queue->credit_bytes;
 682                 }
 683         }
 684 }
 685
 686 static int xen_register_watchers(struct xenbus_device *dev, struct xenvif *vif)
 687 {
 688         int err = 0;
 689         char *node;
 690         unsigned maxlen = strlen(dev->nodename) + sizeof("/rate");
 691
 692         if (vif->credit_watch.node)
 693                 return -EADDRINUSE;
 694
 695         node = kmalloc(maxlen, GFP_KERNEL);
 696         if (!node)
 697                 return -ENOMEM;
 698         snprintf(node, maxlen, "%s/rate", dev->nodename);
 699         vif->credit_watch.node = node;
 700         vif->credit_watch.callback = xen_net_rate_changed;
 701         err = register_xenbus_watch(&vif->credit_watch);
 702         if (err) {
 703                 pr_err("Failed to set watcher %s\n", vif->credit_watch.node);
 704                 kfree(node);
 705                 vif->credit_watch.node = NULL;
 706                 vif->credit_watch.callback = NULL;
 707         }
 708         return err;
 709 }
 710
 711 static void xen_unregister_watchers(struct xenvif *vif)
 712 {
 713         if (vif->credit_watch.node) {
 714                 unregister_xenbus_watch(&vif->credit_watch);
 715                 kfree(vif->credit_watch.node);
 716                 vif->credit_watch.node = NULL;
 717         }
 718 }
 719
 720 static void unregister_hotplug_status_watch(struct backend_info *be)
 721 {
 722         if (be->have_hotplug_status_watch) {
 723                 unregister_xenbus_watch(&be->hotplug_status_watch);
 724                 kfree(be->hotplug_status_watch.node);
 725         }
 726         be->have_hotplug_status_watch = 0;
 727 }
 728
 729 static void hotplug_status_changed(struct xenbus_watch *watch,
 730                                    const char **vec,
 731                                    unsigned int vec_size)
 732 {
 733         struct backend_info *be = container_of(watch,
 734                                                struct backend_info,
 735                                                hotplug_status_watch);
 736         char *str;
 737         unsigned int len;
 738
 739         str = xenbus_read(XBT_NIL, be->dev->nodename, "hotplug-status", &len);
 740         if (IS_ERR(str))
 741                 return;
 742         if (len == sizeof("connected")-1 && !memcmp(str, "connected", len)) {
 743                 /* Complete any pending state change */
 744                 xenbus_switch_state(be->dev, be->state);
 745
 746                 /* Not interested in this watch anymore. */
 747                 unregister_hotplug_status_watch(be);
 748         }
 749         kfree(str);
 750 }
 751
 752 static void connect(struct backend_info *be)
 753 {
 754         int err;
 755         struct xenbus_device *dev = be->dev;
 756         unsigned long credit_bytes, credit_usec;
 757         unsigned int queue_index;
 758         unsigned int requested_num_queues;
 759         struct xenvif_queue *queue;
 760
 761         /* Check whether the frontend requested multiple queues
 762          * and read the number requested.
 763          */
 764         err = xenbus_scanf(XBT_NIL, dev->otherend,
 765                            "multi-queue-num-queues",
 766                            "%u", &requested_num_queues);
 767         if (err < 0) {
 768                 requested_num_queues = 1; /* Fall back to single queue */
 769         } else if (requested_num_queues > xenvif_max_queues) {
 770                 /* buggy or malicious guest */
 771                 xenbus_dev_fatal(dev, err,
 772                                  "guest requested %u queues, exceeding the maximum of %u.",
 773                                  requested_num_queues, xenvif_max_queues);
 774                 return;
 775         }
 776
 777         err = xen_net_read_mac(dev, be->vif->fe_dev_addr);
 778         if (err) {
 779                 xenbus_dev_fatal(dev, err, "parsing %s/mac", dev->nodename);
 780                 return;
 781         }
 782
 783         xen_net_read_rate(dev, &credit_bytes, &credit_usec);
 784         xen_unregister_watchers(be->vif);
 785         xen_register_watchers(dev, be->vif);
 786         read_xenbus_vif_flags(be);
 787
 788         /* Use the number of queues requested by the frontend */
 789         be->vif->queues = vzalloc(requested_num_queues *
 790                                   sizeof(struct xenvif_queue));
 791         if (!be->vif->queues) {
 792                 xenbus_dev_fatal(dev, -ENOMEM,
 793                                  "allocating queues");
 794                 return;
 795         }
 796
 797         be->vif->num_queues = requested_num_queues;
 798         be->vif->stalled_queues = requested_num_queues;
 799
 800         for (queue_index = 0; queue_index < requested_num_queues; ++queue_index) {
 801                 queue = &be->vif->queues[queue_index];
 802                 queue->vif = be->vif;
 803                 queue->id = queue_index;
 804                 snprintf(queue->name, sizeof(queue->name), "%s-q%u",
 805                                 be->vif->dev->name, queue->id);
 806
 807                 err = xenvif_init_queue(queue);
 808                 if (err) {
 809                         /* xenvif_init_queue() cleans up after itself on
 810                          * failure, but we need to clean up any previously
 811                          * initialised queues. Set num_queues to i so that
 812                          * earlier queues can be destroyed using the regular
 813                          * disconnect logic.
 814                          */
 815                         be->vif->num_queues = queue_index;
 816                         goto err;
 817                 }
 818
 819                 queue->credit_bytes = credit_bytes;
 820                 queue->remaining_credit = credit_bytes;
 821                 queue->credit_usec = credit_usec;
 822
 823                 err = connect_rings(be, queue);
 824                 if (err) {
 825                         /* connect_rings() cleans up after itself on failure,
 826                          * but we need to clean up after xenvif_init_queue() here,
 827                          * and also clean up any previously initialised queues.
 828                          */
 829                         xenvif_deinit_queue(queue);
 830                         be->vif->num_queues = queue_index;
 831                         goto err;
 832                 }
 833         }
 834
 835 #ifdef CONFIG_DEBUG_FS
 836         xenvif_debugfs_addif(be->vif);
 837 #endif /* CONFIG_DEBUG_FS */
 838
 839         /* Initialisation completed, tell core driver the number of
 840          * active queues.
 841          */
 842         rtnl_lock();
 843         netif_set_real_num_tx_queues(be->vif->dev, requested_num_queues);
 844         netif_set_real_num_rx_queues(be->vif->dev, requested_num_queues);
 845         rtnl_unlock();
 846
 847         xenvif_carrier_on(be->vif);
 848
 849         unregister_hotplug_status_watch(be);
 850         err = xenbus_watch_pathfmt(dev, &be->hotplug_status_watch,
 851                                    hotplug_status_changed,
 852                                    "%s/%s", dev->nodename, "hotplug-status");
 853         if (!err)
 854                 be->have_hotplug_status_watch = 1;
 855
 856         netif_tx_wake_all_queues(be->vif->dev);
 857
 858         return;
 859
 860 err:
 861         if (be->vif->num_queues > 0)
 862                 xenvif_disconnect(be->vif); /* Clean up existing queues */
 863         vfree(be->vif->queues);
 864         be->vif->queues = NULL;
 865         be->vif->num_queues = 0;
 866         return;
 867 }
 868
 869
 870 static int connect_rings(struct backend_info *be, struct xenvif_queue *queue)
 871 {
 872         struct xenbus_device *dev = be->dev;
 873         unsigned int num_queues = queue->vif->num_queues;
 874         unsigned long tx_ring_ref, rx_ring_ref;
 875         unsigned int tx_evtchn, rx_evtchn;
 876         int err;
 877         char *xspath;
 878         size_t xspathsize;
 879         const size_t xenstore_path_ext_size = 11; /* sufficient for "/queue-NNN" */
 880
 881         /* If the frontend requested 1 queue, or we have fallen back
 882          * to single queue due to lack of frontend support for multi-
 883          * queue, expect the remaining XenStore keys in the toplevel
 884          * directory. Otherwise, expect them in a subdirectory called
 885          * queue-N.
 886          */
 887         if (num_queues == 1) {
 888                 xspath = kzalloc(strlen(dev->otherend) + 1, GFP_KERNEL);
 889                 if (!xspath) {
 890                         xenbus_dev_fatal(dev, -ENOMEM,
 891                                          "reading ring references");
 892                         return -ENOMEM;
 893                 }
 894                 strcpy(xspath, dev->otherend);
 895         } else {
 896                 xspathsize = strlen(dev->otherend) + xenstore_path_ext_size;
 897                 xspath = kzalloc(xspathsize, GFP_KERNEL);
 898                 if (!xspath) {
 899                         xenbus_dev_fatal(dev, -ENOMEM,
 900                                          "reading ring references");
 901                         return -ENOMEM;
 902                 }
 903                 snprintf(xspath, xspathsize, "%s/queue-%u", dev->otherend,
 904                          queue->id);
 905         }
 906
 907         err = xenbus_gather(XBT_NIL, xspath,
 908                             "tx-ring-ref", "%lu", &tx_ring_ref,
 909                             "rx-ring-ref", "%lu", &rx_ring_ref, NULL);
 910         if (err) {
 911                 xenbus_dev_fatal(dev, err,
 912                                  "reading %s/ring-ref",
 913                                  xspath);
 914                 goto err;
 915         }
 916
 917         /* Try split event channels first, then single event channel. */
 918         err = xenbus_gather(XBT_NIL, xspath,
 919                             "event-channel-tx", "%u", &tx_evtchn,
 920                             "event-channel-rx", "%u", &rx_evtchn, NULL);
 921         if (err < 0) {
 922                 err = xenbus_scanf(XBT_NIL, xspath,
 923                                    "event-channel", "%u", &tx_evtchn);
 924                 if (err < 0) {
 925                         xenbus_dev_fatal(dev, err,
 926                                          "reading %s/event-channel(-tx/rx)",
 927                                          xspath);
 928                         goto err;
 929                 }
 930                 rx_evtchn = tx_evtchn;
 931         }
 932
 933         /* Map the shared frame, irq etc. */
 934         err = xenvif_connect(queue, tx_ring_ref, rx_ring_ref,
 935                              tx_evtchn, rx_evtchn);
 936         if (err) {
 937                 xenbus_dev_fatal(dev, err,
 938                                  "mapping shared-frames %lu/%lu port tx %u rx %u",
 939                                  tx_ring_ref, rx_ring_ref,
 940                                  tx_evtchn, rx_evtchn);
 941                 goto err;
 942         }
 943
 944         err = 0;
 945 err: /* Regular return falls through with err == 0 */
 946         kfree(xspath);
 947         return err;
 948 }
 949
 950 static int read_xenbus_vif_flags(struct backend_info *be)
 951 {
 952         struct xenvif *vif = be->vif;
 953         struct xenbus_device *dev = be->dev;
 954         unsigned int rx_copy;
 955         int err, val;
 956
 957         err = xenbus_scanf(XBT_NIL, dev->otherend, "request-rx-copy", "%u",
 958                            &rx_copy);
 959         if (err == -ENOENT) {
 960                 err = 0;
 961                 rx_copy = 0;
 962         }
 963         if (err < 0) {
 964                 xenbus_dev_fatal(dev, err, "reading %s/request-rx-copy",
 965                                  dev->otherend);
 966                 return err;
 967         }
 968         if (!rx_copy)
 969                 return -EOPNOTSUPP;
 970
 971         if (xenbus_scanf(XBT_NIL, dev->otherend,
 972                          "feature-rx-notify", "%d", &val) < 0)
 973                 val = 0;
 974         if (!val) {
 975                 /* - Reduce drain timeout to poll more frequently for
 976                  *   Rx requests.
 977                  * - Disable Rx stall detection.
 978                  */
 979                 be->vif->drain_timeout = msecs_to_jiffies(30);
 980                 be->vif->stall_timeout = 0;
 981         }
 982
 983         if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-sg",
 984                          "%d", &val) < 0)
 985                 val = 0;
 986         vif->can_sg = !!val;
 987
 988         vif->gso_mask = 0;
 989         vif->gso_prefix_mask = 0;
 990
 991         if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-gso-tcpv4",
 992                          "%d", &val) < 0)
 993                 val = 0;
 994         if (val)
 995                 vif->gso_mask |= GSO_BIT(TCPV4);
 996
 997         if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-gso-tcpv4-prefix",
 998                          "%d", &val) < 0)
 999                 val = 0;
1000         if (val)
1001                 vif->gso_prefix_mask |= GSO_BIT(TCPV4);
1002
1003         if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-gso-tcpv6",
1004                          "%d", &val) < 0)
1005                 val = 0;
1006         if (val)
1007                 vif->gso_mask |= GSO_BIT(TCPV6);
1008
1009         if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-gso-tcpv6-prefix",
1010                          "%d", &val) < 0)
1011                 val = 0;
1012         if (val)
1013                 vif->gso_prefix_mask |= GSO_BIT(TCPV6);
1014
1015         if (vif->gso_mask & vif->gso_prefix_mask) {
1016                 xenbus_dev_fatal(dev, err,
1017                                  "%s: gso and gso prefix flags are not "
1018                                  "mutually exclusive",
1019                                  dev->otherend);
1020                 return -EOPNOTSUPP;
1021         }
1022
1023         if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-no-csum-offload",
1024                          "%d", &val) < 0)
1025                 val = 0;
1026         vif->ip_csum = !val;
1027
1028         if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-ipv6-csum-offload",
1029                          "%d", &val) < 0)
1030                 val = 0;
1031         vif->ipv6_csum = !!val;
1032
1033         if (xenbus_scanf(XBT_NIL, dev->otherend, "request-multicast-control",
1034                          "%d", &val) < 0)
1035                 val = 0;
1036         vif->multicast_control = !!val;
1037
1038         return 0;
1039 }
1040
1041 static const struct xenbus_device_id netback_ids[] = {
1042         { "vif" },
1043         { "" }
1044 };
1045
1046 static struct xenbus_driver netback_driver = {
1047         .ids = netback_ids,
1048         .probe = netback_probe,
1049         .remove = netback_remove,
1050         .uevent = netback_uevent,
1051         .otherend_changed = frontend_changed,
1052 };
1053
1054 int xenvif_xenbus_init(void)
1055 {
1056         return xenbus_register_backend(&netback_driver);
1057 }
1058
1059 void xenvif_xenbus_fini(void)
1060 {
1061         return xenbus_unregister_driver(&netback_driver);
1062 }