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_disconnect(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         err = xenbus_switch_state(dev, XenbusStateInitWait);
 126         if (err)
 127                 goto fail;
 128
 129         /* This kicks hotplug scripts, so do it immediately. */
 130         backend_create_xenvif(be);
 131
 132         return 0;
 133
 134 abort_transaction:
 135         xenbus_transaction_end(xbt, 1);
 136         xenbus_dev_fatal(dev, err, "%s", message);
 137 fail:
 138         pr_debug("failed");
 139         netback_remove(dev);
 140         return err;
 141 }
 142
 143
 144 /*
 145  * Handle the creation of the hotplug script environment.  We add the script
 146  * and vif variables to the environment, for the benefit of the vif-* hotplug
 147  * scripts.
 148  */
 149 static int netback_uevent(struct xenbus_device *xdev,
 150                           struct kobj_uevent_env *env)
 151 {
 152         struct backend_info *be = dev_get_drvdata(&xdev->dev);
 153         char *val;
 154
 155         val = xenbus_read(XBT_NIL, xdev->nodename, "script", NULL);
 156         if (IS_ERR(val)) {
 157                 int err = PTR_ERR(val);
 158                 xenbus_dev_fatal(xdev, err, "reading script");
 159                 return err;
 160         } else {
 161                 if (add_uevent_var(env, "script=%s", val)) {
 162                         kfree(val);
 163                         return -ENOMEM;
 164                 }
 165                 kfree(val);
 166         }
 167
 168         if (!be || !be->vif)
 169                 return 0;
 170
 171         return add_uevent_var(env, "vif=%s", be->vif->dev->name);
 172 }
 173
 174
 175 static void backend_create_xenvif(struct backend_info *be)
 176 {
 177         int err;
 178         long handle;
 179         struct xenbus_device *dev = be->dev;
 180
 181         if (be->vif != NULL)
 182                 return;
 183
 184         err = xenbus_scanf(XBT_NIL, dev->nodename, "handle", "%li", &handle);
 185         if (err != 1) {
 186                 xenbus_dev_fatal(dev, err, "reading handle");
 187                 return;
 188         }
 189
 190         be->vif = xenvif_alloc(&dev->dev, dev->otherend_id, handle);
 191         if (IS_ERR(be->vif)) {
 192                 err = PTR_ERR(be->vif);
 193                 be->vif = NULL;
 194                 xenbus_dev_fatal(dev, err, "creating interface");
 195                 return;
 196         }
 197
 198         kobject_uevent(&dev->dev.kobj, KOBJ_ONLINE);
 199 }
 200
 201
 202 static void disconnect_backend(struct xenbus_device *dev)
 203 {
 204         struct backend_info *be = dev_get_drvdata(&dev->dev);
 205
 206         if (be->vif) {
 207                 xenbus_rm(XBT_NIL, dev->nodename, "hotplug-status");
 208                 xenvif_disconnect(be->vif);
 209                 be->vif = NULL;
 210         }
 211 }
 212
 213 /**
 214  * Callback received when the frontend's state changes.
 215  */
 216 static void frontend_changed(struct xenbus_device *dev,
 217                              enum xenbus_state frontend_state)
 218 {
 219         struct backend_info *be = dev_get_drvdata(&dev->dev);
 220
 221         pr_debug("frontend state %s", xenbus_strstate(frontend_state));
 222
 223         be->frontend_state = frontend_state;
 224
 225         switch (frontend_state) {
 226         case XenbusStateInitialising:
 227                 if (dev->state == XenbusStateClosed) {
 228                         printk(KERN_INFO "%s: %s: prepare for reconnect\n",
 229                                __func__, dev->nodename);
 230                         xenbus_switch_state(dev, XenbusStateInitWait);
 231                 }
 232                 break;
 233
 234         case XenbusStateInitialised:
 235                 break;
 236
 237         case XenbusStateConnected:
 238                 if (dev->state == XenbusStateConnected)
 239                         break;
 240                 backend_create_xenvif(be);
 241                 if (be->vif)
 242                         connect(be);
 243                 break;
 244
 245         case XenbusStateClosing:
 246                 if (be->vif)
 247                         kobject_uevent(&dev->dev.kobj, KOBJ_OFFLINE);
 248                 disconnect_backend(dev);
 249                 xenbus_switch_state(dev, XenbusStateClosing);
 250                 break;
 251
 252         case XenbusStateClosed:
 253                 xenbus_switch_state(dev, XenbusStateClosed);
 254                 if (xenbus_dev_is_online(dev))
 255                         break;
 256                 /* fall through if not online */
 257         case XenbusStateUnknown:
 258                 device_unregister(&dev->dev);
 259                 break;
 260
 261         default:
 262                 xenbus_dev_fatal(dev, -EINVAL, "saw state %d at frontend",
 263                                  frontend_state);
 264                 break;
 265         }
 266 }
 267
 268
 269 static void xen_net_read_rate(struct xenbus_device *dev,
 270                               unsigned long *bytes, unsigned long *usec)
 271 {
 272         char *s, *e;
 273         unsigned long b, u;
 274         char *ratestr;
 275
 276         /* Default to unlimited bandwidth. */
 277         *bytes = ~0UL;
 278         *usec = 0;
 279
 280         ratestr = xenbus_read(XBT_NIL, dev->nodename, "rate", NULL);
 281         if (IS_ERR(ratestr))
 282                 return;
 283
 284         s = ratestr;
 285         b = simple_strtoul(s, &e, 10);
 286         if ((s == e) || (*e != ','))
 287                 goto fail;
 288
 289         s = e + 1;
 290         u = simple_strtoul(s, &e, 10);
 291         if ((s == e) || (*e != '\0'))
 292                 goto fail;
 293
 294         *bytes = b;
 295         *usec = u;
 296
 297         kfree(ratestr);
 298         return;
 299
 300  fail:
 301         pr_warn("Failed to parse network rate limit. Traffic unlimited.\n");
 302         kfree(ratestr);
 303 }
 304
 305 static int xen_net_read_mac(struct xenbus_device *dev, u8 mac[])
 306 {
 307         char *s, *e, *macstr;
 308         int i;
 309
 310         macstr = s = xenbus_read(XBT_NIL, dev->nodename, "mac", NULL);
 311         if (IS_ERR(macstr))
 312                 return PTR_ERR(macstr);
 313
 314         for (i = 0; i < ETH_ALEN; i++) {
 315                 mac[i] = simple_strtoul(s, &e, 16);
 316                 if ((s == e) || (*e != ((i == ETH_ALEN-1) ? '\0' : ':'))) {
 317                         kfree(macstr);
 318                         return -ENOENT;
 319                 }
 320                 s = e+1;
 321         }
 322
 323         kfree(macstr);
 324         return 0;
 325 }
 326
 327 static void unregister_hotplug_status_watch(struct backend_info *be)
 328 {
 329         if (be->have_hotplug_status_watch) {
 330                 unregister_xenbus_watch(&be->hotplug_status_watch);
 331                 kfree(be->hotplug_status_watch.node);
 332         }
 333         be->have_hotplug_status_watch = 0;
 334 }
 335
 336 static void hotplug_status_changed(struct xenbus_watch *watch,
 337                                    const char **vec,
 338                                    unsigned int vec_size)
 339 {
 340         struct backend_info *be = container_of(watch,
 341                                                struct backend_info,
 342                                                hotplug_status_watch);
 343         char *str;
 344         unsigned int len;
 345
 346         str = xenbus_read(XBT_NIL, be->dev->nodename, "hotplug-status", &len);
 347         if (IS_ERR(str))
 348                 return;
 349         if (len == sizeof("connected")-1 && !memcmp(str, "connected", len)) {
 350                 xenbus_switch_state(be->dev, XenbusStateConnected);
 351                 /* Not interested in this watch anymore. */
 352                 unregister_hotplug_status_watch(be);
 353         }
 354         kfree(str);
 355 }
 356
 357 static void connect(struct backend_info *be)
 358 {
 359         int err;
 360         struct xenbus_device *dev = be->dev;
 361
 362         err = connect_rings(be);
 363         if (err)
 364                 return;
 365
 366         err = xen_net_read_mac(dev, be->vif->fe_dev_addr);
 367         if (err) {
 368                 xenbus_dev_fatal(dev, err, "parsing %s/mac", dev->nodename);
 369                 return;
 370         }
 371
 372         xen_net_read_rate(dev, &be->vif->credit_bytes,
 373                           &be->vif->credit_usec);
 374         be->vif->remaining_credit = be->vif->credit_bytes;
 375
 376         unregister_hotplug_status_watch(be);
 377         err = xenbus_watch_pathfmt(dev, &be->hotplug_status_watch,
 378                                    hotplug_status_changed,
 379                                    "%s/%s", dev->nodename, "hotplug-status");
 380         if (err) {
 381                 /* Switch now, since we can't do a watch. */
 382                 xenbus_switch_state(dev, XenbusStateConnected);
 383         } else {
 384                 be->have_hotplug_status_watch = 1;
 385         }
 386
 387         netif_wake_queue(be->vif->dev);
 388 }
 389
 390
 391 static int connect_rings(struct backend_info *be)
 392 {
 393         struct xenvif *vif = be->vif;
 394         struct xenbus_device *dev = be->dev;
 395         unsigned long tx_ring_ref, rx_ring_ref;
 396         unsigned int evtchn, rx_copy;
 397         int err;
 398         int val;
 399
 400         err = xenbus_gather(XBT_NIL, dev->otherend,
 401                             "tx-ring-ref", "%lu", &tx_ring_ref,
 402                             "rx-ring-ref", "%lu", &rx_ring_ref,
 403                             "event-channel", "%u", &evtchn, NULL);
 404         if (err) {
 405                 xenbus_dev_fatal(dev, err,
 406                                  "reading %s/ring-ref and event-channel",
 407                                  dev->otherend);
 408                 return err;
 409         }
 410
 411         err = xenbus_scanf(XBT_NIL, dev->otherend, "request-rx-copy", "%u",
 412                            &rx_copy);
 413         if (err == -ENOENT) {
 414                 err = 0;
 415                 rx_copy = 0;
 416         }
 417         if (err < 0) {
 418                 xenbus_dev_fatal(dev, err, "reading %s/request-rx-copy",
 419                                  dev->otherend);
 420                 return err;
 421         }
 422         if (!rx_copy)
 423                 return -EOPNOTSUPP;
 424
 425         if (vif->dev->tx_queue_len != 0) {
 426                 if (xenbus_scanf(XBT_NIL, dev->otherend,
 427                                  "feature-rx-notify", "%d", &val) < 0)
 428                         val = 0;
 429                 if (val)
 430                         vif->can_queue = 1;
 431                 else
 432                         /* Must be non-zero for pfifo_fast to work. */
 433                         vif->dev->tx_queue_len = 1;
 434         }
 435
 436         if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-sg",
 437                          "%d", &val) < 0)
 438                 val = 0;
 439         vif->can_sg = !!val;
 440
 441         if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-gso-tcpv4",
 442                          "%d", &val) < 0)
 443                 val = 0;
 444         vif->gso = !!val;
 445
 446         if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-gso-tcpv4-prefix",
 447                          "%d", &val) < 0)
 448                 val = 0;
 449         vif->gso_prefix = !!val;
 450
 451         if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-no-csum-offload",
 452                          "%d", &val) < 0)
 453                 val = 0;
 454         vif->csum = !val;
 455
 456         /* Map the shared frame, irq etc. */
 457         err = xenvif_connect(vif, tx_ring_ref, rx_ring_ref, evtchn);
 458         if (err) {
 459                 xenbus_dev_fatal(dev, err,
 460                                  "mapping shared-frames %lu/%lu port %u",
 461                                  tx_ring_ref, rx_ring_ref, evtchn);
 462                 return err;
 463         }
 464         return 0;
 465 }
 466
 467
 468 /* ** Driver Registration ** */
 469
 470
 471 static const struct xenbus_device_id netback_ids[] = {
 472         { "vif" },
 473         { "" }
 474 };
 475
 476
 477 static DEFINE_XENBUS_DRIVER(netback, ,
 478         .probe = netback_probe,
 479         .remove = netback_remove,
 480         .uevent = netback_uevent,
 481         .otherend_changed = frontend_changed,
 482 );
 483
 484 int xenvif_xenbus_init(void)
 485 {
 486         return xenbus_register_backend(&netback_driver);
 487 }