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
  23 struct backend_info {
  24         struct xenbus_device *dev;
  25         struct xenvif *vif;
  26
  27         /* This is the state that will be reflected in xenstore when any
  28          * active hotplug script completes.
  29          */
  30         enum xenbus_state state;
  31
  32         enum xenbus_state frontend_state;
  33         struct xenbus_watch hotplug_status_watch;
  34         u8 have_hotplug_status_watch:1;
  35 };
  36
  37 static int connect_rings(struct backend_info *);
  38 static void connect(struct backend_info *);
  39 static void backend_create_xenvif(struct backend_info *be);
  40 static void unregister_hotplug_status_watch(struct backend_info *be);
  41 static void set_backend_state(struct backend_info *be,
  42                               enum xenbus_state state);
  43
  44 static int netback_remove(struct xenbus_device *dev)
  45 {
  46         struct backend_info *be = dev_get_drvdata(&dev->dev);
  47
  48         set_backend_state(be, XenbusStateClosed);
  49
  50         unregister_hotplug_status_watch(be);
  51         if (be->vif) {
  52                 kobject_uevent(&dev->dev.kobj, KOBJ_OFFLINE);
  53                 xenbus_rm(XBT_NIL, dev->nodename, "hotplug-status");
  54                 xenvif_free(be->vif);
  55                 be->vif = NULL;
  56         }
  57         kfree(be);
  58         dev_set_drvdata(&dev->dev, NULL);
  59         return 0;
  60 }
  61
  62
  63 /**
  64  * Entry point to this code when a new device is created.  Allocate the basic
  65  * structures and switch to InitWait.
  66  */
  67 static int netback_probe(struct xenbus_device *dev,
  68                          const struct xenbus_device_id *id)
  69 {
  70         const char *message;
  71         struct xenbus_transaction xbt;
  72         int err;
  73         int sg;
  74         struct backend_info *be = kzalloc(sizeof(struct backend_info),
  75                                           GFP_KERNEL);
  76         if (!be) {
  77                 xenbus_dev_fatal(dev, -ENOMEM,
  78                                  "allocating backend structure");
  79                 return -ENOMEM;
  80         }
  81
  82         be->dev = dev;
  83         dev_set_drvdata(&dev->dev, be);
  84
  85         sg = 1;
  86
  87         do {
  88                 err = xenbus_transaction_start(&xbt);
  89                 if (err) {
  90                         xenbus_dev_fatal(dev, err, "starting transaction");
  91                         goto fail;
  92                 }
  93
  94                 err = xenbus_printf(xbt, dev->nodename, "feature-sg", "%d", sg);
  95                 if (err) {
  96                         message = "writing feature-sg";
  97                         goto abort_transaction;
  98                 }
  99
 100                 err = xenbus_printf(xbt, dev->nodename, "feature-gso-tcpv4",
 101                                     "%d", sg);
 102                 if (err) {
 103                         message = "writing feature-gso-tcpv4";
 104                         goto abort_transaction;
 105                 }
 106
 107                 err = xenbus_printf(xbt, dev->nodename, "feature-gso-tcpv6",
 108                                     "%d", sg);
 109                 if (err) {
 110                         message = "writing feature-gso-tcpv6";
 111                         goto abort_transaction;
 112                 }
 113
 114                 /* We support partial checksum setup for IPv6 packets */
 115                 err = xenbus_printf(xbt, dev->nodename,
 116                                     "feature-ipv6-csum-offload",
 117                                     "%d", 1);
 118                 if (err) {
 119                         message = "writing feature-ipv6-csum-offload";
 120                         goto abort_transaction;
 121                 }
 122
 123                 /* We support rx-copy path. */
 124                 err = xenbus_printf(xbt, dev->nodename,
 125                                     "feature-rx-copy", "%d", 1);
 126                 if (err) {
 127                         message = "writing feature-rx-copy";
 128                         goto abort_transaction;
 129                 }
 130
 131                 /*
 132                  * We don't support rx-flip path (except old guests who don't
 133                  * grok this feature flag).
 134                  */
 135                 err = xenbus_printf(xbt, dev->nodename,
 136                                     "feature-rx-flip", "%d", 0);
 137                 if (err) {
 138                         message = "writing feature-rx-flip";
 139                         goto abort_transaction;
 140                 }
 141
 142                 err = xenbus_transaction_end(xbt, 0);
 143         } while (err == -EAGAIN);
 144
 145         if (err) {
 146                 xenbus_dev_fatal(dev, err, "completing transaction");
 147                 goto fail;
 148         }
 149
 150         /*
 151          * Split event channels support, this is optional so it is not
 152          * put inside the above loop.
 153          */
 154         err = xenbus_printf(XBT_NIL, dev->nodename,
 155                             "feature-split-event-channels",
 156                             "%u", separate_tx_rx_irq);
 157         if (err)
 158                 pr_debug("Error writing feature-split-event-channels\n");
 159
 160         err = xenbus_switch_state(dev, XenbusStateInitWait);
 161         if (err)
 162                 goto fail;
 163
 164         be->state = XenbusStateInitWait;
 165
 166         /* This kicks hotplug scripts, so do it immediately. */
 167         backend_create_xenvif(be);
 168
 169         return 0;
 170
 171 abort_transaction:
 172         xenbus_transaction_end(xbt, 1);
 173         xenbus_dev_fatal(dev, err, "%s", message);
 174 fail:
 175         pr_debug("failed\n");
 176         netback_remove(dev);
 177         return err;
 178 }
 179
 180
 181 /*
 182  * Handle the creation of the hotplug script environment.  We add the script
 183  * and vif variables to the environment, for the benefit of the vif-* hotplug
 184  * scripts.
 185  */
 186 static int netback_uevent(struct xenbus_device *xdev,
 187                           struct kobj_uevent_env *env)
 188 {
 189         struct backend_info *be = dev_get_drvdata(&xdev->dev);
 190         char *val;
 191
 192         val = xenbus_read(XBT_NIL, xdev->nodename, "script", NULL);
 193         if (IS_ERR(val)) {
 194                 int err = PTR_ERR(val);
 195                 xenbus_dev_fatal(xdev, err, "reading script");
 196                 return err;
 197         } else {
 198                 if (add_uevent_var(env, "script=%s", val)) {
 199                         kfree(val);
 200                         return -ENOMEM;
 201                 }
 202                 kfree(val);
 203         }
 204
 205         if (!be || !be->vif)
 206                 return 0;
 207
 208         return add_uevent_var(env, "vif=%s", be->vif->dev->name);
 209 }
 210
 211
 212 static void backend_create_xenvif(struct backend_info *be)
 213 {
 214         int err;
 215         long handle;
 216         struct xenbus_device *dev = be->dev;
 217
 218         if (be->vif != NULL)
 219                 return;
 220
 221         err = xenbus_scanf(XBT_NIL, dev->nodename, "handle", "%li", &handle);
 222         if (err != 1) {
 223                 xenbus_dev_fatal(dev, err, "reading handle");
 224                 return;
 225         }
 226
 227         be->vif = xenvif_alloc(&dev->dev, dev->otherend_id, handle);
 228         if (IS_ERR(be->vif)) {
 229                 err = PTR_ERR(be->vif);
 230                 be->vif = NULL;
 231                 xenbus_dev_fatal(dev, err, "creating interface");
 232                 return;
 233         }
 234
 235         kobject_uevent(&dev->dev.kobj, KOBJ_ONLINE);
 236 }
 237
 238 static void backend_disconnect(struct backend_info *be)
 239 {
 240         if (be->vif)
 241                 xenvif_disconnect(be->vif);
 242 }
 243
 244 static void backend_connect(struct backend_info *be)
 245 {
 246         if (be->vif)
 247                 connect(be);
 248 }
 249
 250 static inline void backend_switch_state(struct backend_info *be,
 251                                         enum xenbus_state state)
 252 {
 253         struct xenbus_device *dev = be->dev;
 254
 255         pr_debug("%s -> %s\n", dev->nodename, xenbus_strstate(state));
 256         be->state = state;
 257
 258         /* If we are waiting for a hotplug script then defer the
 259          * actual xenbus state change.
 260          */
 261         if (!be->have_hotplug_status_watch)
 262                 xenbus_switch_state(dev, state);
 263 }
 264
 265 /* Handle backend state transitions:
 266  *
 267  * The backend state starts in InitWait and the following transitions are
 268  * allowed.
 269  *
 270  * InitWait -> Connected
 271  *
 272  *    ^    \         |
 273  *    |     \        |
 274  *    |      \       |
 275  *    |       \      |
 276  *    |        \     |
 277  *    |         \    |
 278  *    |          V   V
 279  *
 280  *  Closed  <-> Closing
 281  *
 282  * The state argument specifies the eventual state of the backend and the
 283  * function transitions to that state via the shortest path.
 284  */
 285 static void set_backend_state(struct backend_info *be,
 286                               enum xenbus_state state)
 287 {
 288         while (be->state != state) {
 289                 switch (be->state) {
 290                 case XenbusStateClosed:
 291                         switch (state) {
 292                         case XenbusStateInitWait:
 293                         case XenbusStateConnected:
 294                                 pr_info("%s: prepare for reconnect\n",
 295                                         be->dev->nodename);
 296                                 backend_switch_state(be, XenbusStateInitWait);
 297                                 break;
 298                         case XenbusStateClosing:
 299                                 backend_switch_state(be, XenbusStateClosing);
 300                                 break;
 301                         default:
 302                                 BUG();
 303                         }
 304                         break;
 305                 case XenbusStateInitWait:
 306                         switch (state) {
 307                         case XenbusStateConnected:
 308                                 backend_connect(be);
 309                                 backend_switch_state(be, XenbusStateConnected);
 310                                 break;
 311                         case XenbusStateClosing:
 312                         case XenbusStateClosed:
 313                                 backend_switch_state(be, XenbusStateClosing);
 314                                 break;
 315                         default:
 316                                 BUG();
 317                         }
 318                         break;
 319                 case XenbusStateConnected:
 320                         switch (state) {
 321                         case XenbusStateInitWait:
 322                         case XenbusStateClosing:
 323                         case XenbusStateClosed:
 324                                 backend_disconnect(be);
 325                                 backend_switch_state(be, XenbusStateClosing);
 326                                 break;
 327                         default:
 328                                 BUG();
 329                         }
 330                         break;
 331                 case XenbusStateClosing:
 332                         switch (state) {
 333                         case XenbusStateInitWait:
 334                         case XenbusStateConnected:
 335                         case XenbusStateClosed:
 336                                 backend_switch_state(be, XenbusStateClosed);
 337                                 break;
 338                         default:
 339                                 BUG();
 340                         }
 341                         break;
 342                 default:
 343                         BUG();
 344                 }
 345         }
 346 }
 347
 348 /**
 349  * Callback received when the frontend's state changes.
 350  */
 351 static void frontend_changed(struct xenbus_device *dev,
 352                              enum xenbus_state frontend_state)
 353 {
 354         struct backend_info *be = dev_get_drvdata(&dev->dev);
 355
 356         pr_debug("%s -> %s\n", dev->otherend, xenbus_strstate(frontend_state));
 357
 358         be->frontend_state = frontend_state;
 359
 360         switch (frontend_state) {
 361         case XenbusStateInitialising:
 362                 set_backend_state(be, XenbusStateInitWait);
 363                 break;
 364
 365         case XenbusStateInitialised:
 366                 break;
 367
 368         case XenbusStateConnected:
 369                 set_backend_state(be, XenbusStateConnected);
 370                 break;
 371
 372         case XenbusStateClosing:
 373                 set_backend_state(be, XenbusStateClosing);
 374                 break;
 375
 376         case XenbusStateClosed:
 377                 set_backend_state(be, XenbusStateClosed);
 378                 if (xenbus_dev_is_online(dev))
 379                         break;
 380                 /* fall through if not online */
 381         case XenbusStateUnknown:
 382                 set_backend_state(be, XenbusStateClosed);
 383                 device_unregister(&dev->dev);
 384                 break;
 385
 386         default:
 387                 xenbus_dev_fatal(dev, -EINVAL, "saw state %d at frontend",
 388                                  frontend_state);
 389                 break;
 390         }
 391 }
 392
 393
 394 static void xen_net_read_rate(struct xenbus_device *dev,
 395                               unsigned long *bytes, unsigned long *usec)
 396 {
 397         char *s, *e;
 398         unsigned long b, u;
 399         char *ratestr;
 400
 401         /* Default to unlimited bandwidth. */
 402         *bytes = ~0UL;
 403         *usec = 0;
 404
 405         ratestr = xenbus_read(XBT_NIL, dev->nodename, "rate", NULL);
 406         if (IS_ERR(ratestr))
 407                 return;
 408
 409         s = ratestr;
 410         b = simple_strtoul(s, &e, 10);
 411         if ((s == e) || (*e != ','))
 412                 goto fail;
 413
 414         s = e + 1;
 415         u = simple_strtoul(s, &e, 10);
 416         if ((s == e) || (*e != '\0'))
 417                 goto fail;
 418
 419         *bytes = b;
 420         *usec = u;
 421
 422         kfree(ratestr);
 423         return;
 424
 425  fail:
 426         pr_warn("Failed to parse network rate limit. Traffic unlimited.\n");
 427         kfree(ratestr);
 428 }
 429
 430 static int xen_net_read_mac(struct xenbus_device *dev, u8 mac[])
 431 {
 432         char *s, *e, *macstr;
 433         int i;
 434
 435         macstr = s = xenbus_read(XBT_NIL, dev->nodename, "mac", NULL);
 436         if (IS_ERR(macstr))
 437                 return PTR_ERR(macstr);
 438
 439         for (i = 0; i < ETH_ALEN; i++) {
 440                 mac[i] = simple_strtoul(s, &e, 16);
 441                 if ((s == e) || (*e != ((i == ETH_ALEN-1) ? '\0' : ':'))) {
 442                         kfree(macstr);
 443                         return -ENOENT;
 444                 }
 445                 s = e+1;
 446         }
 447
 448         kfree(macstr);
 449         return 0;
 450 }
 451
 452 static void unregister_hotplug_status_watch(struct backend_info *be)
 453 {
 454         if (be->have_hotplug_status_watch) {
 455                 unregister_xenbus_watch(&be->hotplug_status_watch);
 456                 kfree(be->hotplug_status_watch.node);
 457         }
 458         be->have_hotplug_status_watch = 0;
 459 }
 460
 461 static void hotplug_status_changed(struct xenbus_watch *watch,
 462                                    const char **vec,
 463                                    unsigned int vec_size)
 464 {
 465         struct backend_info *be = container_of(watch,
 466                                                struct backend_info,
 467                                                hotplug_status_watch);
 468         char *str;
 469         unsigned int len;
 470
 471         str = xenbus_read(XBT_NIL, be->dev->nodename, "hotplug-status", &len);
 472         if (IS_ERR(str))
 473                 return;
 474         if (len == sizeof("connected")-1 && !memcmp(str, "connected", len)) {
 475                 /* Complete any pending state change */
 476                 xenbus_switch_state(be->dev, be->state);
 477
 478                 /* Not interested in this watch anymore. */
 479                 unregister_hotplug_status_watch(be);
 480         }
 481         kfree(str);
 482 }
 483
 484 static void connect(struct backend_info *be)
 485 {
 486         int err;
 487         struct xenbus_device *dev = be->dev;
 488
 489         err = connect_rings(be);
 490         if (err)
 491                 return;
 492
 493         err = xen_net_read_mac(dev, be->vif->fe_dev_addr);
 494         if (err) {
 495                 xenbus_dev_fatal(dev, err, "parsing %s/mac", dev->nodename);
 496                 return;
 497         }
 498
 499         xen_net_read_rate(dev, &be->vif->credit_bytes,
 500                           &be->vif->credit_usec);
 501         be->vif->remaining_credit = be->vif->credit_bytes;
 502
 503         unregister_hotplug_status_watch(be);
 504         err = xenbus_watch_pathfmt(dev, &be->hotplug_status_watch,
 505                                    hotplug_status_changed,
 506                                    "%s/%s", dev->nodename, "hotplug-status");
 507         if (!err)
 508                 be->have_hotplug_status_watch = 1;
 509
 510         netif_wake_queue(be->vif->dev);
 511 }
 512
 513
 514 static int connect_rings(struct backend_info *be)
 515 {
 516         struct xenvif *vif = be->vif;
 517         struct xenbus_device *dev = be->dev;
 518         unsigned long tx_ring_ref, rx_ring_ref;
 519         unsigned int tx_evtchn, rx_evtchn, rx_copy;
 520         int err;
 521         int val;
 522
 523         err = xenbus_gather(XBT_NIL, dev->otherend,
 524                             "tx-ring-ref", "%lu", &tx_ring_ref,
 525                             "rx-ring-ref", "%lu", &rx_ring_ref, NULL);
 526         if (err) {
 527                 xenbus_dev_fatal(dev, err,
 528                                  "reading %s/ring-ref",
 529                                  dev->otherend);
 530                 return err;
 531         }
 532
 533         /* Try split event channels first, then single event channel. */
 534         err = xenbus_gather(XBT_NIL, dev->otherend,
 535                             "event-channel-tx", "%u", &tx_evtchn,
 536                             "event-channel-rx", "%u", &rx_evtchn, NULL);
 537         if (err < 0) {
 538                 err = xenbus_scanf(XBT_NIL, dev->otherend,
 539                                    "event-channel", "%u", &tx_evtchn);
 540                 if (err < 0) {
 541                         xenbus_dev_fatal(dev, err,
 542                                          "reading %s/event-channel(-tx/rx)",
 543                                          dev->otherend);
 544                         return err;
 545                 }
 546                 rx_evtchn = tx_evtchn;
 547         }
 548
 549         err = xenbus_scanf(XBT_NIL, dev->otherend, "request-rx-copy", "%u",
 550                            &rx_copy);
 551         if (err == -ENOENT) {
 552                 err = 0;
 553                 rx_copy = 0;
 554         }
 555         if (err < 0) {
 556                 xenbus_dev_fatal(dev, err, "reading %s/request-rx-copy",
 557                                  dev->otherend);
 558                 return err;
 559         }
 560         if (!rx_copy)
 561                 return -EOPNOTSUPP;
 562
 563         if (vif->dev->tx_queue_len != 0) {
 564                 if (xenbus_scanf(XBT_NIL, dev->otherend,
 565                                  "feature-rx-notify", "%d", &val) < 0)
 566                         val = 0;
 567                 if (val)
 568                         vif->can_queue = 1;
 569                 else
 570                         /* Must be non-zero for pfifo_fast to work. */
 571                         vif->dev->tx_queue_len = 1;
 572         }
 573
 574         if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-sg",
 575                          "%d", &val) < 0)
 576                 val = 0;
 577         vif->can_sg = !!val;
 578
 579         vif->gso_mask = 0;
 580         vif->gso_prefix_mask = 0;
 581
 582         if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-gso-tcpv4",
 583                          "%d", &val) < 0)
 584                 val = 0;
 585         if (val)
 586                 vif->gso_mask |= GSO_BIT(TCPV4);
 587
 588         if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-gso-tcpv4-prefix",
 589                          "%d", &val) < 0)
 590                 val = 0;
 591         if (val)
 592                 vif->gso_prefix_mask |= GSO_BIT(TCPV4);
 593
 594         if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-gso-tcpv6",
 595                          "%d", &val) < 0)
 596                 val = 0;
 597         if (val)
 598                 vif->gso_mask |= GSO_BIT(TCPV6);
 599
 600         if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-gso-tcpv6-prefix",
 601                          "%d", &val) < 0)
 602                 val = 0;
 603         if (val)
 604                 vif->gso_prefix_mask |= GSO_BIT(TCPV6);
 605
 606         if (vif->gso_mask & vif->gso_prefix_mask) {
 607                 xenbus_dev_fatal(dev, err,
 608                                  "%s: gso and gso prefix flags are not "
 609                                  "mutually exclusive",
 610                                  dev->otherend);
 611                 return -EOPNOTSUPP;
 612         }
 613
 614         if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-no-csum-offload",
 615                          "%d", &val) < 0)
 616                 val = 0;
 617         vif->ip_csum = !val;
 618
 619         if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-ipv6-csum-offload",
 620                          "%d", &val) < 0)
 621                 val = 0;
 622         vif->ipv6_csum = !!val;
 623
 624         /* Map the shared frame, irq etc. */
 625         err = xenvif_connect(vif, tx_ring_ref, rx_ring_ref,
 626                              tx_evtchn, rx_evtchn);
 627         if (err) {
 628                 xenbus_dev_fatal(dev, err,
 629                                  "mapping shared-frames %lu/%lu port tx %u rx %u",
 630                                  tx_ring_ref, rx_ring_ref,
 631                                  tx_evtchn, rx_evtchn);
 632                 return err;
 633         }
 634         return 0;
 635 }
 636
 637
 638 /* ** Driver Registration ** */
 639
 640
 641 static const struct xenbus_device_id netback_ids[] = {
 642         { "vif" },
 643         { "" }
 644 };
 645
 646
 647 static DEFINE_XENBUS_DRIVER(netback, ,
 648         .probe = netback_probe,
 649         .remove = netback_remove,
 650         .uevent = netback_uevent,
 651         .otherend_changed = frontend_changed,
 652 );
 653
 654 int xenvif_xenbus_init(void)
 655 {
 656         return xenbus_register_backend(&netback_driver);
 657 }
 658
 659 void xenvif_xenbus_fini(void)
 660 {
 661         return xenbus_unregister_driver(&netback_driver);
 662 }