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