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, write to the Free Software
  19  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  20 */
  21
  22 #include "common.h"
  23
  24 struct backend_info {
  25         struct xenbus_device *dev;
  26         struct xenvif *vif;
  27         enum xenbus_state frontend_state;
  28         struct xenbus_watch hotplug_status_watch;
  29         u8 have_hotplug_status_watch:1;
  30 };
  31
  32 static int connect_rings(struct backend_info *);
  33 static void connect(struct backend_info *);
  34 static void backend_create_xenvif(struct backend_info *be);
  35 static void unregister_hotplug_status_watch(struct backend_info *be);
  36
  37 static int netback_remove(struct xenbus_device *dev)
  38 {
  39         struct backend_info *be = dev_get_drvdata(&dev->dev);
  40
  41         unregister_hotplug_status_watch(be);
  42         if (be->vif) {
  43                 kobject_uevent(&dev->dev.kobj, KOBJ_OFFLINE);
  44                 xenbus_rm(XBT_NIL, dev->nodename, "hotplug-status");
  45                 xenvif_free(be->vif);
  46                 be->vif = NULL;
  47         }
  48         kfree(be);
  49         dev_set_drvdata(&dev->dev, NULL);
  50         return 0;
  51 }
  52
  53
  54 /**
  55  * Entry point to this code when a new device is created.  Allocate the basic
  56  * structures and switch to InitWait.
  57  */
  58 static int netback_probe(struct xenbus_device *dev,
  59                          const struct xenbus_device_id *id)
  60 {
  61         const char *message;
  62         struct xenbus_transaction xbt;
  63         int err;
  64         int sg;
  65         struct backend_info *be = kzalloc(sizeof(struct backend_info),
  66                                           GFP_KERNEL);
  67         if (!be) {
  68                 xenbus_dev_fatal(dev, -ENOMEM,
  69                                  "allocating backend structure");
  70                 return -ENOMEM;
  71         }
  72
  73         be->dev = dev;
  74         dev_set_drvdata(&dev->dev, be);
  75
  76         sg = 1;
  77
  78         do {
  79                 err = xenbus_transaction_start(&xbt);
  80                 if (err) {
  81                         xenbus_dev_fatal(dev, err, "starting transaction");
  82                         goto fail;
  83                 }
  84
  85                 err = xenbus_printf(xbt, dev->nodename, "feature-sg", "%d", sg);
  86                 if (err) {
  87                         message = "writing feature-sg";
  88                         goto abort_transaction;
  89                 }
  90
  91                 err = xenbus_printf(xbt, dev->nodename, "feature-gso-tcpv4",
  92                                     "%d", sg);
  93                 if (err) {
  94                         message = "writing feature-gso-tcpv4";
  95                         goto abort_transaction;
  96                 }
  97
  98                 /* We support rx-copy path. */
  99                 err = xenbus_printf(xbt, dev->nodename,
 100                                     "feature-rx-copy", "%d", 1);
 101                 if (err) {
 102                         message = "writing feature-rx-copy";
 103                         goto abort_transaction;
 104                 }
 105
 106                 /*
 107                  * We don't support rx-flip path (except old guests who don't
 108                  * grok this feature flag).
 109                  */
 110                 err = xenbus_printf(xbt, dev->nodename,
 111                                     "feature-rx-flip", "%d", 0);
 112                 if (err) {
 113                         message = "writing feature-rx-flip";
 114                         goto abort_transaction;
 115                 }
 116
 117                 err = xenbus_transaction_end(xbt, 0);
 118         } while (err == -EAGAIN);
 119
 120         if (err) {
 121                 xenbus_dev_fatal(dev, err, "completing transaction");
 122                 goto fail;
 123         }
 124
 125         /*
 126          * Split event channels support, this is optional so it is not
 127          * put inside the above loop.
 128          */
 129         err = xenbus_printf(XBT_NIL, dev->nodename,
 130                             "feature-split-event-channels",
 131                             "%u", separate_tx_rx_irq);
 132         if (err)
 133                 pr_debug("Error writing feature-split-event-channels\n");
 134
 135         err = xenbus_switch_state(dev, XenbusStateInitWait);
 136         if (err)
 137                 goto fail;
 138
 139         /* This kicks hotplug scripts, so do it immediately. */
 140         backend_create_xenvif(be);
 141
 142         return 0;
 143
 144 abort_transaction:
 145         xenbus_transaction_end(xbt, 1);
 146         xenbus_dev_fatal(dev, err, "%s", message);
 147 fail:
 148         pr_debug("failed\n");
 149         netback_remove(dev);
 150         return err;
 151 }
 152
 153
 154 /*
 155  * Handle the creation of the hotplug script environment.  We add the script
 156  * and vif variables to the environment, for the benefit of the vif-* hotplug
 157  * scripts.
 158  */
 159 static int netback_uevent(struct xenbus_device *xdev,
 160                           struct kobj_uevent_env *env)
 161 {
 162         struct backend_info *be = dev_get_drvdata(&xdev->dev);
 163         char *val;
 164
 165         val = xenbus_read(XBT_NIL, xdev->nodename, "script", NULL);
 166         if (IS_ERR(val)) {
 167                 int err = PTR_ERR(val);
 168                 xenbus_dev_fatal(xdev, err, "reading script");
 169                 return err;
 170         } else {
 171                 if (add_uevent_var(env, "script=%s", val)) {
 172                         kfree(val);
 173                         return -ENOMEM;
 174                 }
 175                 kfree(val);
 176         }
 177
 178         if (!be || !be->vif)
 179                 return 0;
 180
 181         return add_uevent_var(env, "vif=%s", be->vif->dev->name);
 182 }
 183
 184
 185 static void backend_create_xenvif(struct backend_info *be)
 186 {
 187         int err;
 188         long handle;
 189         struct xenbus_device *dev = be->dev;
 190
 191         if (be->vif != NULL)
 192                 return;
 193
 194         err = xenbus_scanf(XBT_NIL, dev->nodename, "handle", "%li", &handle);
 195         if (err != 1) {
 196                 xenbus_dev_fatal(dev, err, "reading handle");
 197                 return;
 198         }
 199
 200         be->vif = xenvif_alloc(&dev->dev, dev->otherend_id, handle);
 201         if (IS_ERR(be->vif)) {
 202                 err = PTR_ERR(be->vif);
 203                 be->vif = NULL;
 204                 xenbus_dev_fatal(dev, err, "creating interface");
 205                 return;
 206         }
 207
 208         kobject_uevent(&dev->dev.kobj, KOBJ_ONLINE);
 209 }
 210
 211
 212 static void disconnect_backend(struct xenbus_device *dev)
 213 {
 214         struct backend_info *be = dev_get_drvdata(&dev->dev);
 215
 216         if (be->vif)
 217                 xenvif_disconnect(be->vif);
 218 }
 219
 220 static void destroy_backend(struct xenbus_device *dev)
 221 {
 222         struct backend_info *be = dev_get_drvdata(&dev->dev);
 223
 224         if (be->vif) {
 225                 kobject_uevent(&dev->dev.kobj, KOBJ_OFFLINE);
 226                 xenbus_rm(XBT_NIL, dev->nodename, "hotplug-status");
 227                 xenvif_free(be->vif);
 228                 be->vif = NULL;
 229         }
 230 }
 231
 232 /**
 233  * Callback received when the frontend's state changes.
 234  */
 235 static void frontend_changed(struct xenbus_device *dev,
 236                              enum xenbus_state frontend_state)
 237 {
 238         struct backend_info *be = dev_get_drvdata(&dev->dev);
 239
 240         pr_debug("frontend state %s\n", xenbus_strstate(frontend_state));
 241
 242         be->frontend_state = frontend_state;
 243
 244         switch (frontend_state) {
 245         case XenbusStateInitialising:
 246                 if (dev->state == XenbusStateClosed) {
 247                         pr_info("%s: prepare for reconnect\n", dev->nodename);
 248                         xenbus_switch_state(dev, XenbusStateInitWait);
 249                 }
 250                 break;
 251
 252         case XenbusStateInitialised:
 253                 break;
 254
 255         case XenbusStateConnected:
 256                 if (dev->state == XenbusStateConnected)
 257                         break;
 258                 if (be->vif)
 259                         connect(be);
 260                 break;
 261
 262         case XenbusStateClosing:
 263                 disconnect_backend(dev);
 264                 xenbus_switch_state(dev, XenbusStateClosing);
 265                 break;
 266
 267         case XenbusStateClosed:
 268                 xenbus_switch_state(dev, XenbusStateClosed);
 269                 if (xenbus_dev_is_online(dev))
 270                         break;
 271                 destroy_backend(dev);
 272                 /* fall through if not online */
 273         case XenbusStateUnknown:
 274                 device_unregister(&dev->dev);
 275                 break;
 276
 277         default:
 278                 xenbus_dev_fatal(dev, -EINVAL, "saw state %d at frontend",
 279                                  frontend_state);
 280                 break;
 281         }
 282 }
 283
 284
 285 static void xen_net_read_rate(struct xenbus_device *dev,
 286                               unsigned long *bytes, unsigned long *usec)
 287 {
 288         char *s, *e;
 289         unsigned long b, u;
 290         char *ratestr;
 291
 292         /* Default to unlimited bandwidth. */
 293         *bytes = ~0UL;
 294         *usec = 0;
 295
 296         ratestr = xenbus_read(XBT_NIL, dev->nodename, "rate", NULL);
 297         if (IS_ERR(ratestr))
 298                 return;
 299
 300         s = ratestr;
 301         b = simple_strtoul(s, &e, 10);
 302         if ((s == e) || (*e != ','))
 303                 goto fail;
 304
 305         s = e + 1;
 306         u = simple_strtoul(s, &e, 10);
 307         if ((s == e) || (*e != '\0'))
 308                 goto fail;
 309
 310         *bytes = b;
 311         *usec = u;
 312
 313         kfree(ratestr);
 314         return;
 315
 316  fail:
 317         pr_warn("Failed to parse network rate limit. Traffic unlimited.\n");
 318         kfree(ratestr);
 319 }
 320
 321 static int xen_net_read_mac(struct xenbus_device *dev, u8 mac[])
 322 {
 323         char *s, *e, *macstr;
 324         int i;
 325
 326         macstr = s = xenbus_read(XBT_NIL, dev->nodename, "mac", NULL);
 327         if (IS_ERR(macstr))
 328                 return PTR_ERR(macstr);
 329
 330         for (i = 0; i < ETH_ALEN; i++) {
 331                 mac[i] = simple_strtoul(s, &e, 16);
 332                 if ((s == e) || (*e != ((i == ETH_ALEN-1) ? '\0' : ':'))) {
 333                         kfree(macstr);
 334                         return -ENOENT;
 335                 }
 336                 s = e+1;
 337         }
 338
 339         kfree(macstr);
 340         return 0;
 341 }
 342
 343 static void unregister_hotplug_status_watch(struct backend_info *be)
 344 {
 345         if (be->have_hotplug_status_watch) {
 346                 unregister_xenbus_watch(&be->hotplug_status_watch);
 347                 kfree(be->hotplug_status_watch.node);
 348         }
 349         be->have_hotplug_status_watch = 0;
 350 }
 351
 352 static void hotplug_status_changed(struct xenbus_watch *watch,
 353                                    const char **vec,
 354                                    unsigned int vec_size)
 355 {
 356         struct backend_info *be = container_of(watch,
 357                                                struct backend_info,
 358                                                hotplug_status_watch);
 359         char *str;
 360         unsigned int len;
 361
 362         str = xenbus_read(XBT_NIL, be->dev->nodename, "hotplug-status", &len);
 363         if (IS_ERR(str))
 364                 return;
 365         if (len == sizeof("connected")-1 && !memcmp(str, "connected", len)) {
 366                 xenbus_switch_state(be->dev, XenbusStateConnected);
 367                 /* Not interested in this watch anymore. */
 368                 unregister_hotplug_status_watch(be);
 369         }
 370         kfree(str);
 371 }
 372
 373 static void connect(struct backend_info *be)
 374 {
 375         int err;
 376         struct xenbus_device *dev = be->dev;
 377
 378         err = connect_rings(be);
 379         if (err)
 380                 return;
 381
 382         err = xen_net_read_mac(dev, be->vif->fe_dev_addr);
 383         if (err) {
 384                 xenbus_dev_fatal(dev, err, "parsing %s/mac", dev->nodename);
 385                 return;
 386         }
 387
 388         xen_net_read_rate(dev, &be->vif->credit_bytes,
 389                           &be->vif->credit_usec);
 390         be->vif->remaining_credit = be->vif->credit_bytes;
 391
 392         unregister_hotplug_status_watch(be);
 393         err = xenbus_watch_pathfmt(dev, &be->hotplug_status_watch,
 394                                    hotplug_status_changed,
 395                                    "%s/%s", dev->nodename, "hotplug-status");
 396         if (err) {
 397                 /* Switch now, since we can't do a watch. */
 398                 xenbus_switch_state(dev, XenbusStateConnected);
 399         } else {
 400                 be->have_hotplug_status_watch = 1;
 401         }
 402
 403         netif_wake_queue(be->vif->dev);
 404 }
 405
 406
 407 static int connect_rings(struct backend_info *be)
 408 {
 409         struct xenvif *vif = be->vif;
 410         struct xenbus_device *dev = be->dev;
 411         unsigned long tx_ring_ref, rx_ring_ref;
 412         unsigned int tx_evtchn, rx_evtchn, rx_copy;
 413         int err;
 414         int val;
 415
 416         err = xenbus_gather(XBT_NIL, dev->otherend,
 417                             "tx-ring-ref", "%lu", &tx_ring_ref,
 418                             "rx-ring-ref", "%lu", &rx_ring_ref, NULL);
 419         if (err) {
 420                 xenbus_dev_fatal(dev, err,
 421                                  "reading %s/ring-ref",
 422                                  dev->otherend);
 423                 return err;
 424         }
 425
 426         /* Try split event channels first, then single event channel. */
 427         err = xenbus_gather(XBT_NIL, dev->otherend,
 428                             "event-channel-tx", "%u", &tx_evtchn,
 429                             "event-channel-rx", "%u", &rx_evtchn, NULL);
 430         if (err < 0) {
 431                 err = xenbus_scanf(XBT_NIL, dev->otherend,
 432                                    "event-channel", "%u", &tx_evtchn);
 433                 if (err < 0) {
 434                         xenbus_dev_fatal(dev, err,
 435                                          "reading %s/event-channel(-tx/rx)",
 436                                          dev->otherend);
 437                         return err;
 438                 }
 439                 rx_evtchn = tx_evtchn;
 440         }
 441
 442         err = xenbus_scanf(XBT_NIL, dev->otherend, "request-rx-copy", "%u",
 443                            &rx_copy);
 444         if (err == -ENOENT) {
 445                 err = 0;
 446                 rx_copy = 0;
 447         }
 448         if (err < 0) {
 449                 xenbus_dev_fatal(dev, err, "reading %s/request-rx-copy",
 450                                  dev->otherend);
 451                 return err;
 452         }
 453         if (!rx_copy)
 454                 return -EOPNOTSUPP;
 455
 456         if (vif->dev->tx_queue_len != 0) {
 457                 if (xenbus_scanf(XBT_NIL, dev->otherend,
 458                                  "feature-rx-notify", "%d", &val) < 0)
 459                         val = 0;
 460                 if (val)
 461                         vif->can_queue = 1;
 462                 else
 463                         /* Must be non-zero for pfifo_fast to work. */
 464                         vif->dev->tx_queue_len = 1;
 465         }
 466
 467         if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-sg",
 468                          "%d", &val) < 0)
 469                 val = 0;
 470         vif->can_sg = !!val;
 471
 472         if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-gso-tcpv4",
 473                          "%d", &val) < 0)
 474                 val = 0;
 475         vif->gso = !!val;
 476
 477         if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-gso-tcpv4-prefix",
 478                          "%d", &val) < 0)
 479                 val = 0;
 480         vif->gso_prefix = !!val;
 481
 482         if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-no-csum-offload",
 483                          "%d", &val) < 0)
 484                 val = 0;
 485         vif->csum = !val;
 486
 487         /* Map the shared frame, irq etc. */
 488         err = xenvif_connect(vif, tx_ring_ref, rx_ring_ref,
 489                              tx_evtchn, rx_evtchn);
 490         if (err) {
 491                 xenbus_dev_fatal(dev, err,
 492                                  "mapping shared-frames %lu/%lu port tx %u rx %u",
 493                                  tx_ring_ref, rx_ring_ref,
 494                                  tx_evtchn, rx_evtchn);
 495                 return err;
 496         }
 497         return 0;
 498 }
 499
 500
 501 /* ** Driver Registration ** */
 502
 503
 504 static const struct xenbus_device_id netback_ids[] = {
 505         { "vif" },
 506         { "" }
 507 };
 508
 509
 510 static DEFINE_XENBUS_DRIVER(netback, ,
 511         .probe = netback_probe,
 512         .remove = netback_remove,
 513         .uevent = netback_uevent,
 514         .otherend_changed = frontend_changed,
 515 );
 516
 517 int xenvif_xenbus_init(void)
 518 {
 519         return xenbus_register_backend(&netback_driver);
 520 }
 521
 522 void xenvif_xenbus_fini(void)
 523 {
 524         return xenbus_unregister_driver(&netback_driver);
 525 }