drivers/xen/xen-pciback/xenbus.c

   1 /*
   2  * PCI Backend Xenbus Setup - handles setup with frontend and xend
   3  *
   4  *   Author: Ryan Wilson <hap9@epoch.ncsc.mil>
   5  */
   6
   7 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
   8
   9 #include <linux/moduleparam.h>
  10 #include <linux/init.h>
  11 #include <linux/list.h>
  12 #include <linux/vmalloc.h>
  13 #include <linux/workqueue.h>
  14 #include <xen/xenbus.h>
  15 #include <xen/events.h>
  16 #include <asm/xen/pci.h>
  17 #include "pciback.h"
  18
  19 #define INVALID_EVTCHN_IRQ  (-1)
  20
  21 static bool __read_mostly passthrough;
  22 module_param(passthrough, bool, S_IRUGO);
  23 MODULE_PARM_DESC(passthrough,
  24         "Option to specify how to export PCI topology to guest:\n"\
  25         " 0 - (default) Hide the true PCI topology and makes the frontend\n"\
  26         "   there is a single PCI bus with only the exported devices on it.\n"\
  27         "   For example, a device at 03:05.0 will be re-assigned to 00:00.0\n"\
  28         "   while second device at 02:1a.1 will be re-assigned to 00:01.1.\n"\
  29         " 1 - Passthrough provides a real view of the PCI topology to the\n"\
  30         "   frontend (for example, a device at 06:01.b will still appear at\n"\
  31         "   06:01.b to the frontend). This is similar to how Xen 2.0.x\n"\
  32         "   exposed PCI devices to its driver domains. This may be required\n"\
  33         "   for drivers which depend on finding their hardward in certain\n"\
  34         "   bus/slot locations.");
  35
  36 static struct xen_pcibk_device *alloc_pdev(struct xenbus_device *xdev)
  37 {
  38         struct xen_pcibk_device *pdev;
  39
  40         pdev = kzalloc(sizeof(struct xen_pcibk_device), GFP_KERNEL);
  41         if (pdev == NULL)
  42                 goto out;
  43         dev_dbg(&xdev->dev, "allocated pdev @ 0x%p\n", pdev);
  44
  45         pdev->xdev = xdev;
  46
  47         mutex_init(&pdev->dev_lock);
  48
  49         pdev->sh_info = NULL;
  50         pdev->evtchn_irq = INVALID_EVTCHN_IRQ;
  51         pdev->be_watching = 0;
  52
  53         INIT_WORK(&pdev->op_work, xen_pcibk_do_op);
  54
  55         if (xen_pcibk_init_devices(pdev)) {
  56                 kfree(pdev);
  57                 pdev = NULL;
  58         }
  59
  60         dev_set_drvdata(&xdev->dev, pdev);
  61
  62 out:
  63         return pdev;
  64 }
  65
  66 static void xen_pcibk_disconnect(struct xen_pcibk_device *pdev)
  67 {
  68         mutex_lock(&pdev->dev_lock);
  69         /* Ensure the guest can't trigger our handler before removing devices */
  70         if (pdev->evtchn_irq != INVALID_EVTCHN_IRQ) {
  71                 unbind_from_irqhandler(pdev->evtchn_irq, pdev);
  72                 pdev->evtchn_irq = INVALID_EVTCHN_IRQ;
  73         }
  74
  75         /* If the driver domain started an op, make sure we complete it
  76          * before releasing the shared memory */
  77
  78         flush_work(&pdev->op_work);
  79
  80         if (pdev->sh_info != NULL) {
  81                 xenbus_unmap_ring_vfree(pdev->xdev, pdev->sh_info);
  82                 pdev->sh_info = NULL;
  83         }
  84         mutex_unlock(&pdev->dev_lock);
  85 }
  86
  87 static void free_pdev(struct xen_pcibk_device *pdev)
  88 {
  89         if (pdev->be_watching) {
  90                 unregister_xenbus_watch(&pdev->be_watch);
  91                 pdev->be_watching = 0;
  92         }
  93
  94         xen_pcibk_disconnect(pdev);
  95
  96         /* N.B. This calls pcistub_put_pci_dev which does the FLR on all
  97          * of the PCIe devices. */
  98         xen_pcibk_release_devices(pdev);
  99
 100         dev_set_drvdata(&pdev->xdev->dev, NULL);
 101         pdev->xdev = NULL;
 102
 103         kfree(pdev);
 104 }
 105
 106 static int xen_pcibk_do_attach(struct xen_pcibk_device *pdev, int gnt_ref,
 107                              int remote_evtchn)
 108 {
 109         int err = 0;
 110         void *vaddr;
 111
 112         dev_dbg(&pdev->xdev->dev,
 113                 "Attaching to frontend resources - gnt_ref=%d evtchn=%d\n",
 114                 gnt_ref, remote_evtchn);
 115
 116         err = xenbus_map_ring_valloc(pdev->xdev, &gnt_ref, 1, &vaddr);
 117         if (err < 0) {
 118                 xenbus_dev_fatal(pdev->xdev, err,
 119                                 "Error mapping other domain page in ours.");
 120                 goto out;
 121         }
 122
 123         pdev->sh_info = vaddr;
 124
 125         err = bind_interdomain_evtchn_to_irqhandler(
 126                 pdev->xdev->otherend_id, remote_evtchn, xen_pcibk_handle_event,
 127                 0, DRV_NAME, pdev);
 128         if (err < 0) {
 129                 xenbus_dev_fatal(pdev->xdev, err,
 130                                  "Error binding event channel to IRQ");
 131                 goto out;
 132         }
 133         pdev->evtchn_irq = err;
 134         err = 0;
 135
 136         dev_dbg(&pdev->xdev->dev, "Attached!\n");
 137 out:
 138         return err;
 139 }
 140
 141 static int xen_pcibk_attach(struct xen_pcibk_device *pdev)
 142 {
 143         int err = 0;
 144         int gnt_ref, remote_evtchn;
 145         char *magic = NULL;
 146
 147
 148         mutex_lock(&pdev->dev_lock);
 149         /* Make sure we only do this setup once */
 150         if (xenbus_read_driver_state(pdev->xdev->nodename) !=
 151             XenbusStateInitialised)
 152                 goto out;
 153
 154         /* Wait for frontend to state that it has published the configuration */
 155         if (xenbus_read_driver_state(pdev->xdev->otherend) !=
 156             XenbusStateInitialised)
 157                 goto out;
 158
 159         dev_dbg(&pdev->xdev->dev, "Reading frontend config\n");
 160
 161         err = xenbus_gather(XBT_NIL, pdev->xdev->otherend,
 162                             "pci-op-ref", "%u", &gnt_ref,
 163                             "event-channel", "%u", &remote_evtchn,
 164                             "magic", NULL, &magic, NULL);
 165         if (err) {
 166                 /* If configuration didn't get read correctly, wait longer */
 167                 xenbus_dev_fatal(pdev->xdev, err,
 168                                  "Error reading configuration from frontend");
 169                 goto out;
 170         }
 171
 172         if (magic == NULL || strcmp(magic, XEN_PCI_MAGIC) != 0) {
 173                 xenbus_dev_fatal(pdev->xdev, -EFAULT,
 174                                  "version mismatch (%s/%s) with pcifront - "
 175                                  "halting " DRV_NAME,
 176                                  magic, XEN_PCI_MAGIC);
 177                 err = -EFAULT;
 178                 goto out;
 179         }
 180
 181         err = xen_pcibk_do_attach(pdev, gnt_ref, remote_evtchn);
 182         if (err)
 183                 goto out;
 184
 185         dev_dbg(&pdev->xdev->dev, "Connecting...\n");
 186
 187         err = xenbus_switch_state(pdev->xdev, XenbusStateConnected);
 188         if (err)
 189                 xenbus_dev_fatal(pdev->xdev, err,
 190                                  "Error switching to connected state!");
 191
 192         dev_dbg(&pdev->xdev->dev, "Connected? %d\n", err);
 193 out:
 194         mutex_unlock(&pdev->dev_lock);
 195
 196         kfree(magic);
 197
 198         return err;
 199 }
 200
 201 static int xen_pcibk_publish_pci_dev(struct xen_pcibk_device *pdev,
 202                                    unsigned int domain, unsigned int bus,
 203                                    unsigned int devfn, unsigned int devid)
 204 {
 205         int err;
 206         int len;
 207         char str[64];
 208
 209         len = snprintf(str, sizeof(str), "vdev-%d", devid);
 210         if (unlikely(len >= (sizeof(str) - 1))) {
 211                 err = -ENOMEM;
 212                 goto out;
 213         }
 214
 215         /* Note: The PV protocol uses %02x, don't change it */
 216         err = xenbus_printf(XBT_NIL, pdev->xdev->nodename, str,
 217                             "%04x:%02x:%02x.%02x", domain, bus,
 218                             PCI_SLOT(devfn), PCI_FUNC(devfn));
 219
 220 out:
 221         return err;
 222 }
 223
 224 static int xen_pcibk_export_device(struct xen_pcibk_device *pdev,
 225                                  int domain, int bus, int slot, int func,
 226                                  int devid)
 227 {
 228         struct pci_dev *dev;
 229         int err = 0;
 230
 231         dev_dbg(&pdev->xdev->dev, "exporting dom %x bus %x slot %x func %x\n",
 232                 domain, bus, slot, func);
 233
 234         dev = pcistub_get_pci_dev_by_slot(pdev, domain, bus, slot, func);
 235         if (!dev) {
 236                 err = -EINVAL;
 237                 xenbus_dev_fatal(pdev->xdev, err,
 238                                  "Couldn't locate PCI device "
 239                                  "(%04x:%02x:%02x.%d)! "
 240                                  "perhaps already in-use?",
 241                                  domain, bus, slot, func);
 242                 goto out;
 243         }
 244
 245         err = xen_pcibk_add_pci_dev(pdev, dev, devid,
 246                                     xen_pcibk_publish_pci_dev);
 247         if (err)
 248                 goto out;
 249
 250         dev_info(&dev->dev, "registering for %d\n", pdev->xdev->otherend_id);
 251         if (xen_register_device_domain_owner(dev,
 252                                              pdev->xdev->otherend_id) != 0) {
 253                 dev_err(&dev->dev, "Stealing ownership from dom%d.\n",
 254                         xen_find_device_domain_owner(dev));
 255                 xen_unregister_device_domain_owner(dev);
 256                 xen_register_device_domain_owner(dev, pdev->xdev->otherend_id);
 257         }
 258
 259         /* TODO: It'd be nice to export a bridge and have all of its children
 260          * get exported with it. This may be best done in xend (which will
 261          * have to calculate resource usage anyway) but we probably want to
 262          * put something in here to ensure that if a bridge gets given to a
 263          * driver domain, that all devices under that bridge are not given
 264          * to other driver domains (as he who controls the bridge can disable
 265          * it and stop the other devices from working).
 266          */
 267 out:
 268         return err;
 269 }
 270
 271 static int xen_pcibk_remove_device(struct xen_pcibk_device *pdev,
 272                                  int domain, int bus, int slot, int func)
 273 {
 274         int err = 0;
 275         struct pci_dev *dev;
 276
 277         dev_dbg(&pdev->xdev->dev, "removing dom %x bus %x slot %x func %x\n",
 278                 domain, bus, slot, func);
 279
 280         dev = xen_pcibk_get_pci_dev(pdev, domain, bus, PCI_DEVFN(slot, func));
 281         if (!dev) {
 282                 err = -EINVAL;
 283                 dev_dbg(&pdev->xdev->dev, "Couldn't locate PCI device "
 284                         "(%04x:%02x:%02x.%d)! not owned by this domain\n",
 285                         domain, bus, slot, func);
 286                 goto out;
 287         }
 288
 289         dev_dbg(&dev->dev, "unregistering for %d\n", pdev->xdev->otherend_id);
 290         xen_unregister_device_domain_owner(dev);
 291
 292         /* N.B. This ends up calling pcistub_put_pci_dev which ends up
 293          * doing the FLR. */
 294         xen_pcibk_release_pci_dev(pdev, dev, true /* use the lock. */);
 295
 296 out:
 297         return err;
 298 }
 299
 300 static int xen_pcibk_publish_pci_root(struct xen_pcibk_device *pdev,
 301                                     unsigned int domain, unsigned int bus)
 302 {
 303         unsigned int d, b;
 304         int i, root_num, len, err;
 305         char str[64];
 306
 307         dev_dbg(&pdev->xdev->dev, "Publishing pci roots\n");
 308
 309         err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename,
 310                            "root_num", "%d", &root_num);
 311         if (err == 0 || err == -ENOENT)
 312                 root_num = 0;
 313         else if (err < 0)
 314                 goto out;
 315
 316         /* Verify that we haven't already published this pci root */
 317         for (i = 0; i < root_num; i++) {
 318                 len = snprintf(str, sizeof(str), "root-%d", i);
 319                 if (unlikely(len >= (sizeof(str) - 1))) {
 320                         err = -ENOMEM;
 321                         goto out;
 322                 }
 323
 324                 err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename,
 325                                    str, "%x:%x", &d, &b);
 326                 if (err < 0)
 327                         goto out;
 328                 if (err != 2) {
 329                         err = -EINVAL;
 330                         goto out;
 331                 }
 332
 333                 if (d == domain && b == bus) {
 334                         err = 0;
 335                         goto out;
 336                 }
 337         }
 338
 339         len = snprintf(str, sizeof(str), "root-%d", root_num);
 340         if (unlikely(len >= (sizeof(str) - 1))) {
 341                 err = -ENOMEM;
 342                 goto out;
 343         }
 344
 345         dev_dbg(&pdev->xdev->dev, "writing root %d at %04x:%02x\n",
 346                 root_num, domain, bus);
 347
 348         err = xenbus_printf(XBT_NIL, pdev->xdev->nodename, str,
 349                             "%04x:%02x", domain, bus);
 350         if (err)
 351                 goto out;
 352
 353         err = xenbus_printf(XBT_NIL, pdev->xdev->nodename,
 354                             "root_num", "%d", (root_num + 1));
 355
 356 out:
 357         return err;
 358 }
 359
 360 static int xen_pcibk_reconfigure(struct xen_pcibk_device *pdev)
 361 {
 362         int err = 0;
 363         int num_devs;
 364         int domain, bus, slot, func;
 365         unsigned int substate;
 366         int i, len;
 367         char state_str[64];
 368         char dev_str[64];
 369
 370
 371         dev_dbg(&pdev->xdev->dev, "Reconfiguring device ...\n");
 372
 373         mutex_lock(&pdev->dev_lock);
 374         /* Make sure we only reconfigure once */
 375         if (xenbus_read_driver_state(pdev->xdev->nodename) !=
 376             XenbusStateReconfiguring)
 377                 goto out;
 378
 379         err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename, "num_devs", "%d",
 380                            &num_devs);
 381         if (err != 1) {
 382                 if (err >= 0)
 383                         err = -EINVAL;
 384                 xenbus_dev_fatal(pdev->xdev, err,
 385                                  "Error reading number of devices");
 386                 goto out;
 387         }
 388
 389         for (i = 0; i < num_devs; i++) {
 390                 len = snprintf(state_str, sizeof(state_str), "state-%d", i);
 391                 if (unlikely(len >= (sizeof(state_str) - 1))) {
 392                         err = -ENOMEM;
 393                         xenbus_dev_fatal(pdev->xdev, err,
 394                                          "String overflow while reading "
 395                                          "configuration");
 396                         goto out;
 397                 }
 398                 substate = xenbus_read_unsigned(pdev->xdev->nodename, state_str,
 399                                                 XenbusStateUnknown);
 400
 401                 switch (substate) {
 402                 case XenbusStateInitialising:
 403                         dev_dbg(&pdev->xdev->dev, "Attaching dev-%d ...\n", i);
 404
 405                         len = snprintf(dev_str, sizeof(dev_str), "dev-%d", i);
 406                         if (unlikely(len >= (sizeof(dev_str) - 1))) {
 407                                 err = -ENOMEM;
 408                                 xenbus_dev_fatal(pdev->xdev, err,
 409                                                  "String overflow while "
 410                                                  "reading configuration");
 411                                 goto out;
 412                         }
 413                         err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename,
 414                                            dev_str, "%x:%x:%x.%x",
 415                                            &domain, &bus, &slot, &func);
 416                         if (err < 0) {
 417                                 xenbus_dev_fatal(pdev->xdev, err,
 418                                                  "Error reading device "
 419                                                  "configuration");
 420                                 goto out;
 421                         }
 422                         if (err != 4) {
 423                                 err = -EINVAL;
 424                                 xenbus_dev_fatal(pdev->xdev, err,
 425                                                  "Error parsing pci device "
 426                                                  "configuration");
 427                                 goto out;
 428                         }
 429
 430                         err = xen_pcibk_export_device(pdev, domain, bus, slot,
 431                                                     func, i);
 432                         if (err)
 433                                 goto out;
 434
 435                         /* Publish pci roots. */
 436                         err = xen_pcibk_publish_pci_roots(pdev,
 437                                                 xen_pcibk_publish_pci_root);
 438                         if (err) {
 439                                 xenbus_dev_fatal(pdev->xdev, err,
 440                                                  "Error while publish PCI root"
 441                                                  "buses for frontend");
 442                                 goto out;
 443                         }
 444
 445                         err = xenbus_printf(XBT_NIL, pdev->xdev->nodename,
 446                                             state_str, "%d",
 447                                             XenbusStateInitialised);
 448                         if (err) {
 449                                 xenbus_dev_fatal(pdev->xdev, err,
 450                                                  "Error switching substate of "
 451                                                  "dev-%d\n", i);
 452                                 goto out;
 453                         }
 454                         break;
 455
 456                 case XenbusStateClosing:
 457                         dev_dbg(&pdev->xdev->dev, "Detaching dev-%d ...\n", i);
 458
 459                         len = snprintf(dev_str, sizeof(dev_str), "vdev-%d", i);
 460                         if (unlikely(len >= (sizeof(dev_str) - 1))) {
 461                                 err = -ENOMEM;
 462                                 xenbus_dev_fatal(pdev->xdev, err,
 463                                                  "String overflow while "
 464                                                  "reading configuration");
 465                                 goto out;
 466                         }
 467                         err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename,
 468                                            dev_str, "%x:%x:%x.%x",
 469                                            &domain, &bus, &slot, &func);
 470                         if (err < 0) {
 471                                 xenbus_dev_fatal(pdev->xdev, err,
 472                                                  "Error reading device "
 473                                                  "configuration");
 474                                 goto out;
 475                         }
 476                         if (err != 4) {
 477                                 err = -EINVAL;
 478                                 xenbus_dev_fatal(pdev->xdev, err,
 479                                                  "Error parsing pci device "
 480                                                  "configuration");
 481                                 goto out;
 482                         }
 483
 484                         err = xen_pcibk_remove_device(pdev, domain, bus, slot,
 485                                                     func);
 486                         if (err)
 487                                 goto out;
 488
 489                         /* TODO: If at some point we implement support for pci
 490                          * root hot-remove on pcifront side, we'll need to
 491                          * remove unnecessary xenstore nodes of pci roots here.
 492                          */
 493
 494                         break;
 495
 496                 default:
 497                         break;
 498                 }
 499         }
 500
 501         err = xenbus_switch_state(pdev->xdev, XenbusStateReconfigured);
 502         if (err) {
 503                 xenbus_dev_fatal(pdev->xdev, err,
 504                                  "Error switching to reconfigured state!");
 505                 goto out;
 506         }
 507
 508 out:
 509         mutex_unlock(&pdev->dev_lock);
 510         return 0;
 511 }
 512
 513 static void xen_pcibk_frontend_changed(struct xenbus_device *xdev,
 514                                      enum xenbus_state fe_state)
 515 {
 516         struct xen_pcibk_device *pdev = dev_get_drvdata(&xdev->dev);
 517
 518         dev_dbg(&xdev->dev, "fe state changed %d\n", fe_state);
 519
 520         switch (fe_state) {
 521         case XenbusStateInitialised:
 522                 xen_pcibk_attach(pdev);
 523                 break;
 524
 525         case XenbusStateReconfiguring:
 526                 xen_pcibk_reconfigure(pdev);
 527                 break;
 528
 529         case XenbusStateConnected:
 530                 /* pcifront switched its state from reconfiguring to connected.
 531                  * Then switch to connected state.
 532                  */
 533                 xenbus_switch_state(xdev, XenbusStateConnected);
 534                 break;
 535
 536         case XenbusStateClosing:
 537                 xen_pcibk_disconnect(pdev);
 538                 xenbus_switch_state(xdev, XenbusStateClosing);
 539                 break;
 540
 541         case XenbusStateClosed:
 542                 xen_pcibk_disconnect(pdev);
 543                 xenbus_switch_state(xdev, XenbusStateClosed);
 544                 if (xenbus_dev_is_online(xdev))
 545                         break;
 546                 /* fall through if not online */
 547         case XenbusStateUnknown:
 548                 dev_dbg(&xdev->dev, "frontend is gone! unregister device\n");
 549                 device_unregister(&xdev->dev);
 550                 break;
 551
 552         default:
 553                 break;
 554         }
 555 }
 556
 557 static int xen_pcibk_setup_backend(struct xen_pcibk_device *pdev)
 558 {
 559         /* Get configuration from xend (if available now) */
 560         int domain, bus, slot, func;
 561         int err = 0;
 562         int i, num_devs;
 563         char dev_str[64];
 564         char state_str[64];
 565
 566         mutex_lock(&pdev->dev_lock);
 567         /* It's possible we could get the call to setup twice, so make sure
 568          * we're not already connected.
 569          */
 570         if (xenbus_read_driver_state(pdev->xdev->nodename) !=
 571             XenbusStateInitWait)
 572                 goto out;
 573
 574         dev_dbg(&pdev->xdev->dev, "getting be setup\n");
 575
 576         err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename, "num_devs", "%d",
 577                            &num_devs);
 578         if (err != 1) {
 579                 if (err >= 0)
 580                         err = -EINVAL;
 581                 xenbus_dev_fatal(pdev->xdev, err,
 582                                  "Error reading number of devices");
 583                 goto out;
 584         }
 585
 586         for (i = 0; i < num_devs; i++) {
 587                 int l = snprintf(dev_str, sizeof(dev_str), "dev-%d", i);
 588                 if (unlikely(l >= (sizeof(dev_str) - 1))) {
 589                         err = -ENOMEM;
 590                         xenbus_dev_fatal(pdev->xdev, err,
 591                                          "String overflow while reading "
 592                                          "configuration");
 593                         goto out;
 594                 }
 595
 596                 err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename, dev_str,
 597                                    "%x:%x:%x.%x", &domain, &bus, &slot, &func);
 598                 if (err < 0) {
 599                         xenbus_dev_fatal(pdev->xdev, err,
 600                                          "Error reading device configuration");
 601                         goto out;
 602                 }
 603                 if (err != 4) {
 604                         err = -EINVAL;
 605                         xenbus_dev_fatal(pdev->xdev, err,
 606                                          "Error parsing pci device "
 607                                          "configuration");
 608                         goto out;
 609                 }
 610
 611                 err = xen_pcibk_export_device(pdev, domain, bus, slot, func, i);
 612                 if (err)
 613                         goto out;
 614
 615                 /* Switch substate of this device. */
 616                 l = snprintf(state_str, sizeof(state_str), "state-%d", i);
 617                 if (unlikely(l >= (sizeof(state_str) - 1))) {
 618                         err = -ENOMEM;
 619                         xenbus_dev_fatal(pdev->xdev, err,
 620                                          "String overflow while reading "
 621                                          "configuration");
 622                         goto out;
 623                 }
 624                 err = xenbus_printf(XBT_NIL, pdev->xdev->nodename, state_str,
 625                                     "%d", XenbusStateInitialised);
 626                 if (err) {
 627                         xenbus_dev_fatal(pdev->xdev, err, "Error switching "
 628                                          "substate of dev-%d\n", i);
 629                         goto out;
 630                 }
 631         }
 632
 633         err = xen_pcibk_publish_pci_roots(pdev, xen_pcibk_publish_pci_root);
 634         if (err) {
 635                 xenbus_dev_fatal(pdev->xdev, err,
 636                                  "Error while publish PCI root buses "
 637                                  "for frontend");
 638                 goto out;
 639         }
 640
 641         err = xenbus_switch_state(pdev->xdev, XenbusStateInitialised);
 642         if (err)
 643                 xenbus_dev_fatal(pdev->xdev, err,
 644                                  "Error switching to initialised state!");
 645
 646 out:
 647         mutex_unlock(&pdev->dev_lock);
 648         if (!err)
 649                 /* see if pcifront is already configured (if not, we'll wait) */
 650                 xen_pcibk_attach(pdev);
 651         return err;
 652 }
 653
 654 static void xen_pcibk_be_watch(struct xenbus_watch *watch,
 655                                const char *path, const char *token)
 656 {
 657         struct xen_pcibk_device *pdev =
 658             container_of(watch, struct xen_pcibk_device, be_watch);
 659
 660         switch (xenbus_read_driver_state(pdev->xdev->nodename)) {
 661         case XenbusStateInitWait:
 662                 xen_pcibk_setup_backend(pdev);
 663                 break;
 664
 665         default:
 666                 break;
 667         }
 668 }
 669
 670 static int xen_pcibk_xenbus_probe(struct xenbus_device *dev,
 671                                 const struct xenbus_device_id *id)
 672 {
 673         int err = 0;
 674         struct xen_pcibk_device *pdev = alloc_pdev(dev);
 675
 676         if (pdev == NULL) {
 677                 err = -ENOMEM;
 678                 xenbus_dev_fatal(dev, err,
 679                                  "Error allocating xen_pcibk_device struct");
 680                 goto out;
 681         }
 682
 683         /* wait for xend to configure us */
 684         err = xenbus_switch_state(dev, XenbusStateInitWait);
 685         if (err)
 686                 goto out;
 687
 688         /* watch the backend node for backend configuration information */
 689         err = xenbus_watch_path(dev, dev->nodename, &pdev->be_watch,
 690                                 xen_pcibk_be_watch);
 691         if (err)
 692                 goto out;
 693
 694         pdev->be_watching = 1;
 695
 696         /* We need to force a call to our callback here in case
 697          * xend already configured us!
 698          */
 699         xen_pcibk_be_watch(&pdev->be_watch, NULL, 0);
 700
 701 out:
 702         return err;
 703 }
 704
 705 static int xen_pcibk_xenbus_remove(struct xenbus_device *dev)
 706 {
 707         struct xen_pcibk_device *pdev = dev_get_drvdata(&dev->dev);
 708
 709         if (pdev != NULL)
 710                 free_pdev(pdev);
 711
 712         return 0;
 713 }
 714
 715 static const struct xenbus_device_id xen_pcibk_ids[] = {
 716         {"pci"},
 717         {""},
 718 };
 719
 720 static struct xenbus_driver xen_pcibk_driver = {
 721         .name                   = DRV_NAME,
 722         .ids                    = xen_pcibk_ids,
 723         .probe                  = xen_pcibk_xenbus_probe,
 724         .remove                 = xen_pcibk_xenbus_remove,
 725         .otherend_changed       = xen_pcibk_frontend_changed,
 726 };
 727
 728 const struct xen_pcibk_backend *__read_mostly xen_pcibk_backend;
 729
 730 int __init xen_pcibk_xenbus_register(void)
 731 {
 732         xen_pcibk_backend = &xen_pcibk_vpci_backend;
 733         if (passthrough)
 734                 xen_pcibk_backend = &xen_pcibk_passthrough_backend;
 735         pr_info("backend is %s\n", xen_pcibk_backend->name);
 736         return xenbus_register_backend(&xen_pcibk_driver);
 737 }
 738
 739 void __exit xen_pcibk_xenbus_unregister(void)
 740 {
 741         xenbus_unregister_driver(&xen_pcibk_driver);
 742 }