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 #include <linux/module.h>
   7 #include <linux/init.h>
   8 #include <linux/list.h>
   9 #include <linux/vmalloc.h>
  10 #include <linux/workqueue.h>
  11 #include <xen/xenbus.h>
  12 #include <xen/events.h>
  13 #include <asm/xen/pci.h>
  14 #include "pciback.h"
  15
  16 #define DRV_NAME        "xen-pciback"
  17 #define INVALID_EVTCHN_IRQ  (-1)
  18 struct workqueue_struct *xen_pcibk_wq;
  19
  20 static int __read_mostly passthrough;
  21 module_param(passthrough, bool, S_IRUGO);
  22 MODULE_PARM_DESC(passthrough,
  23         "Option to specify how to export PCI topology to guest:\n"\
  24         " 0 - (default) Hide the true PCI topology and makes the frontend\n"\
  25         "   there is a single PCI bus with only the exported devices on it.\n"\
  26         "   For example, a device at 03:05.0 will be re-assigned to 00:00.0\n"\
  27         "   while second device at 02:1a.1 will be re-assigned to 00:01.1.\n"\
  28         " 1 - Passthrough provides a real view of the PCI topology to the\n"\
  29         "   frontend (for example, a device at 06:01.b will still appear at\n"\
  30         "   06:01.b to the frontend). This is similar to how Xen 2.0.x\n"\
  31         "   exposed PCI devices to its driver domains. This may be required\n"\
  32         "   for drivers which depend on finding their hardward in certain\n"\
  33         "   bus/slot locations.");
  34
  35 static struct xen_pcibk_device *alloc_pdev(struct xenbus_device *xdev)
  36 {
  37         struct xen_pcibk_device *pdev;
  38
  39         pdev = kzalloc(sizeof(struct xen_pcibk_device), GFP_KERNEL);
  40         if (pdev == NULL)
  41                 goto out;
  42         dev_dbg(&xdev->dev, "allocated pdev @ 0x%p\n", pdev);
  43
  44         pdev->xdev = xdev;
  45         dev_set_drvdata(&xdev->dev, pdev);
  46
  47         spin_lock_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 out:
  60         return pdev;
  61 }
  62
  63 static void xen_pcibk_disconnect(struct xen_pcibk_device *pdev)
  64 {
  65         spin_lock(&pdev->dev_lock);
  66
  67         /* Ensure the guest can't trigger our handler before removing devices */
  68         if (pdev->evtchn_irq != INVALID_EVTCHN_IRQ) {
  69                 unbind_from_irqhandler(pdev->evtchn_irq, pdev);
  70                 pdev->evtchn_irq = INVALID_EVTCHN_IRQ;
  71         }
  72         spin_unlock(&pdev->dev_lock);
  73
  74         /* If the driver domain started an op, make sure we complete it
  75          * before releasing the shared memory */
  76
  77         /* Note, the workqueue does not use spinlocks at all.*/
  78         flush_workqueue(xen_pcibk_wq);
  79
  80         spin_lock(&pdev->dev_lock);
  81         if (pdev->sh_info != NULL) {
  82                 xenbus_unmap_ring_vfree(pdev->xdev, pdev->sh_info);
  83                 pdev->sh_info = NULL;
  84         }
  85         spin_unlock(&pdev->dev_lock);
  86
  87 }
  88
  89 static void free_pdev(struct xen_pcibk_device *pdev)
  90 {
  91         if (pdev->be_watching) {
  92                 unregister_xenbus_watch(&pdev->be_watch);
  93                 pdev->be_watching = 0;
  94         }
  95
  96         xen_pcibk_disconnect(pdev);
  97
  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, &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         spin_lock(&pdev->dev_lock);
 124         pdev->sh_info = vaddr;
 125         spin_unlock(&pdev->dev_lock);
 126
 127         err = bind_interdomain_evtchn_to_irqhandler(
 128                 pdev->xdev->otherend_id, remote_evtchn, xen_pcibk_handle_event,
 129                 0, DRV_NAME, pdev);
 130         if (err < 0) {
 131                 xenbus_dev_fatal(pdev->xdev, err,
 132                                  "Error binding event channel to IRQ");
 133                 goto out;
 134         }
 135
 136         spin_lock(&pdev->dev_lock);
 137         pdev->evtchn_irq = err;
 138         spin_unlock(&pdev->dev_lock);
 139         err = 0;
 140
 141         dev_dbg(&pdev->xdev->dev, "Attached!\n");
 142 out:
 143         return err;
 144 }
 145
 146 static int xen_pcibk_attach(struct xen_pcibk_device *pdev)
 147 {
 148         int err = 0;
 149         int gnt_ref, remote_evtchn;
 150         char *magic = NULL;
 151
 152
 153         /* Make sure we only do this setup once */
 154         if (xenbus_read_driver_state(pdev->xdev->nodename) !=
 155             XenbusStateInitialised)
 156                 goto out;
 157
 158         /* Wait for frontend to state that it has published the configuration */
 159         if (xenbus_read_driver_state(pdev->xdev->otherend) !=
 160             XenbusStateInitialised)
 161                 goto out;
 162
 163         dev_dbg(&pdev->xdev->dev, "Reading frontend config\n");
 164
 165         err = xenbus_gather(XBT_NIL, pdev->xdev->otherend,
 166                             "pci-op-ref", "%u", &gnt_ref,
 167                             "event-channel", "%u", &remote_evtchn,
 168                             "magic", NULL, &magic, NULL);
 169         if (err) {
 170                 /* If configuration didn't get read correctly, wait longer */
 171                 xenbus_dev_fatal(pdev->xdev, err,
 172                                  "Error reading configuration from frontend");
 173                 goto out;
 174         }
 175
 176         if (magic == NULL || strcmp(magic, XEN_PCI_MAGIC) != 0) {
 177                 xenbus_dev_fatal(pdev->xdev, -EFAULT,
 178                                  "version mismatch (%s/%s) with pcifront - "
 179                                  "halting xen_pcibk",
 180                                  magic, XEN_PCI_MAGIC);
 181                 goto out;
 182         }
 183
 184         err = xen_pcibk_do_attach(pdev, gnt_ref, remote_evtchn);
 185         if (err)
 186                 goto out;
 187
 188         dev_dbg(&pdev->xdev->dev, "Connecting...\n");
 189
 190         err = xenbus_switch_state(pdev->xdev, XenbusStateConnected);
 191         if (err)
 192                 xenbus_dev_fatal(pdev->xdev, err,
 193                                  "Error switching to connected state!");
 194
 195         dev_dbg(&pdev->xdev->dev, "Connected? %d\n", err);
 196 out:
 197
 198         kfree(magic);
 199
 200         return err;
 201 }
 202
 203 static int xen_pcibk_publish_pci_dev(struct xen_pcibk_device *pdev,
 204                                    unsigned int domain, unsigned int bus,
 205                                    unsigned int devfn, unsigned int devid)
 206 {
 207         int err;
 208         int len;
 209         char str[64];
 210
 211         len = snprintf(str, sizeof(str), "vdev-%d", devid);
 212         if (unlikely(len >= (sizeof(str) - 1))) {
 213                 err = -ENOMEM;
 214                 goto out;
 215         }
 216
 217         err = xenbus_printf(XBT_NIL, pdev->xdev->nodename, str,
 218                             "%04x:%02x:%02x.%02x", domain, bus,
 219                             PCI_SLOT(devfn), PCI_FUNC(devfn));
 220
 221 out:
 222         return err;
 223 }
 224
 225 static int xen_pcibk_export_device(struct xen_pcibk_device *pdev,
 226                                  int domain, int bus, int slot, int func,
 227                                  int devid)
 228 {
 229         struct pci_dev *dev;
 230         int err = 0;
 231
 232         dev_dbg(&pdev->xdev->dev, "exporting dom %x bus %x slot %x func %x\n",
 233                 domain, bus, slot, func);
 234
 235         dev = pcistub_get_pci_dev_by_slot(pdev, domain, bus, slot, func);
 236         if (!dev) {
 237                 err = -EINVAL;
 238                 xenbus_dev_fatal(pdev->xdev, err,
 239                                  "Couldn't locate PCI device "
 240                                  "(%04x:%02x:%02x.%01x)! "
 241                                  "perhaps already in-use?",
 242                                  domain, bus, slot, func);
 243                 goto out;
 244         }
 245
 246         err = xen_pcibk_add_pci_dev(pdev, dev, devid,
 247                                     xen_pcibk_publish_pci_dev);
 248         if (err)
 249                 goto out;
 250
 251         dev_dbg(&dev->dev, "registering for %d\n", pdev->xdev->otherend_id);
 252         if (xen_register_device_domain_owner(dev,
 253                                              pdev->xdev->otherend_id) != 0) {
 254                 dev_err(&dev->dev, "device has been assigned to another " \
 255                         "domain! Over-writting the ownership, but beware.\n");
 256                 xen_unregister_device_domain_owner(dev);
 257                 xen_register_device_domain_owner(dev, pdev->xdev->otherend_id);
 258         }
 259
 260         /* TODO: It'd be nice to export a bridge and have all of its children
 261          * get exported with it. This may be best done in xend (which will
 262          * have to calculate resource usage anyway) but we probably want to
 263          * put something in here to ensure that if a bridge gets given to a
 264          * driver domain, that all devices under that bridge are not given
 265          * to other driver domains (as he who controls the bridge can disable
 266          * it and stop the other devices from working).
 267          */
 268 out:
 269         return err;
 270 }
 271
 272 static int xen_pcibk_remove_device(struct xen_pcibk_device *pdev,
 273                                  int domain, int bus, int slot, int func)
 274 {
 275         int err = 0;
 276         struct pci_dev *dev;
 277
 278         dev_dbg(&pdev->xdev->dev, "removing dom %x bus %x slot %x func %x\n",
 279                 domain, bus, slot, func);
 280
 281         dev = xen_pcibk_get_pci_dev(pdev, domain, bus, PCI_DEVFN(slot, func));
 282         if (!dev) {
 283                 err = -EINVAL;
 284                 dev_dbg(&pdev->xdev->dev, "Couldn't locate PCI device "
 285                         "(%04x:%02x:%02x.%01x)! not owned by this domain\n",
 286                         domain, bus, slot, func);
 287                 goto out;
 288         }
 289
 290         dev_dbg(&dev->dev, "unregistering for %d\n", pdev->xdev->otherend_id);
 291         xen_unregister_device_domain_owner(dev);
 292
 293         xen_pcibk_release_pci_dev(pdev, dev);
 294
 295 out:
 296         return err;
 297 }
 298
 299 static int xen_pcibk_publish_pci_root(struct xen_pcibk_device *pdev,
 300                                     unsigned int domain, unsigned int bus)
 301 {
 302         unsigned int d, b;
 303         int i, root_num, len, err;
 304         char str[64];
 305
 306         dev_dbg(&pdev->xdev->dev, "Publishing pci roots\n");
 307
 308         err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename,
 309                            "root_num", "%d", &root_num);
 310         if (err == 0 || err == -ENOENT)
 311                 root_num = 0;
 312         else if (err < 0)
 313                 goto out;
 314
 315         /* Verify that we haven't already published this pci root */
 316         for (i = 0; i < root_num; i++) {
 317                 len = snprintf(str, sizeof(str), "root-%d", i);
 318                 if (unlikely(len >= (sizeof(str) - 1))) {
 319                         err = -ENOMEM;
 320                         goto out;
 321                 }
 322
 323                 err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename,
 324                                    str, "%x:%x", &d, &b);
 325                 if (err < 0)
 326                         goto out;
 327                 if (err != 2) {
 328                         err = -EINVAL;
 329                         goto out;
 330                 }
 331
 332                 if (d == domain && b == bus) {
 333                         err = 0;
 334                         goto out;
 335                 }
 336         }
 337
 338         len = snprintf(str, sizeof(str), "root-%d", root_num);
 339         if (unlikely(len >= (sizeof(str) - 1))) {
 340                 err = -ENOMEM;
 341                 goto out;
 342         }
 343
 344         dev_dbg(&pdev->xdev->dev, "writing root %d at %04x:%02x\n",
 345                 root_num, domain, bus);
 346
 347         err = xenbus_printf(XBT_NIL, pdev->xdev->nodename, str,
 348                             "%04x:%02x", domain, bus);
 349         if (err)
 350                 goto out;
 351
 352         err = xenbus_printf(XBT_NIL, pdev->xdev->nodename,
 353                             "root_num", "%d", (root_num + 1));
 354
 355 out:
 356         return err;
 357 }
 358
 359 static int xen_pcibk_reconfigure(struct xen_pcibk_device *pdev)
 360 {
 361         int err = 0;
 362         int num_devs;
 363         int domain, bus, slot, func;
 364         int substate;
 365         int i, len;
 366         char state_str[64];
 367         char dev_str[64];
 368
 369
 370         dev_dbg(&pdev->xdev->dev, "Reconfiguring device ...\n");
 371
 372         /* Make sure we only reconfigure once */
 373         if (xenbus_read_driver_state(pdev->xdev->nodename) !=
 374             XenbusStateReconfiguring)
 375                 goto out;
 376
 377         err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename, "num_devs", "%d",
 378                            &num_devs);
 379         if (err != 1) {
 380                 if (err >= 0)
 381                         err = -EINVAL;
 382                 xenbus_dev_fatal(pdev->xdev, err,
 383                                  "Error reading number of devices");
 384                 goto out;
 385         }
 386
 387         for (i = 0; i < num_devs; i++) {
 388                 len = snprintf(state_str, sizeof(state_str), "state-%d", i);
 389                 if (unlikely(len >= (sizeof(state_str) - 1))) {
 390                         err = -ENOMEM;
 391                         xenbus_dev_fatal(pdev->xdev, err,
 392                                          "String overflow while reading "
 393                                          "configuration");
 394                         goto out;
 395                 }
 396                 err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename, state_str,
 397                                    "%d", &substate);
 398                 if (err != 1)
 399                         substate = 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         return 0;
 510 }
 511
 512 static void xen_pcibk_frontend_changed(struct xenbus_device *xdev,
 513                                      enum xenbus_state fe_state)
 514 {
 515         struct xen_pcibk_device *pdev = dev_get_drvdata(&xdev->dev);
 516
 517         dev_dbg(&xdev->dev, "fe state changed %d\n", fe_state);
 518
 519         switch (fe_state) {
 520         case XenbusStateInitialised:
 521                 xen_pcibk_attach(pdev);
 522                 break;
 523
 524         case XenbusStateReconfiguring:
 525                 xen_pcibk_reconfigure(pdev);
 526                 break;
 527
 528         case XenbusStateConnected:
 529                 /* pcifront switched its state from reconfiguring to connected.
 530                  * Then switch to connected state.
 531                  */
 532                 xenbus_switch_state(xdev, XenbusStateConnected);
 533                 break;
 534
 535         case XenbusStateClosing:
 536                 xen_pcibk_disconnect(pdev);
 537                 xenbus_switch_state(xdev, XenbusStateClosing);
 538                 break;
 539
 540         case XenbusStateClosed:
 541                 xen_pcibk_disconnect(pdev);
 542                 xenbus_switch_state(xdev, XenbusStateClosed);
 543                 if (xenbus_dev_is_online(xdev))
 544                         break;
 545                 /* fall through if not online */
 546         case XenbusStateUnknown:
 547                 dev_dbg(&xdev->dev, "frontend is gone! unregister device\n");
 548                 device_unregister(&xdev->dev);
 549                 break;
 550
 551         default:
 552                 break;
 553         }
 554 }
 555
 556 static int xen_pcibk_setup_backend(struct xen_pcibk_device *pdev)
 557 {
 558         /* Get configuration from xend (if available now) */
 559         int domain, bus, slot, func;
 560         int err = 0;
 561         int i, num_devs;
 562         char dev_str[64];
 563         char state_str[64];
 564
 565         /* It's possible we could get the call to setup twice, so make sure
 566          * we're not already connected.
 567          */
 568         if (xenbus_read_driver_state(pdev->xdev->nodename) !=
 569             XenbusStateInitWait)
 570                 goto out;
 571
 572         dev_dbg(&pdev->xdev->dev, "getting be setup\n");
 573
 574         err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename, "num_devs", "%d",
 575                            &num_devs);
 576         if (err != 1) {
 577                 if (err >= 0)
 578                         err = -EINVAL;
 579                 xenbus_dev_fatal(pdev->xdev, err,
 580                                  "Error reading number of devices");
 581                 goto out;
 582         }
 583
 584         for (i = 0; i < num_devs; i++) {
 585                 int l = snprintf(dev_str, sizeof(dev_str), "dev-%d", i);
 586                 if (unlikely(l >= (sizeof(dev_str) - 1))) {
 587                         err = -ENOMEM;
 588                         xenbus_dev_fatal(pdev->xdev, err,
 589                                          "String overflow while reading "
 590                                          "configuration");
 591                         goto out;
 592                 }
 593
 594                 err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename, dev_str,
 595                                    "%x:%x:%x.%x", &domain, &bus, &slot, &func);
 596                 if (err < 0) {
 597                         xenbus_dev_fatal(pdev->xdev, err,
 598                                          "Error reading device configuration");
 599                         goto out;
 600                 }
 601                 if (err != 4) {
 602                         err = -EINVAL;
 603                         xenbus_dev_fatal(pdev->xdev, err,
 604                                          "Error parsing pci device "
 605                                          "configuration");
 606                         goto out;
 607                 }
 608
 609                 err = xen_pcibk_export_device(pdev, domain, bus, slot, func, i);
 610                 if (err)
 611                         goto out;
 612
 613                 /* Switch substate of this device. */
 614                 l = snprintf(state_str, sizeof(state_str), "state-%d", i);
 615                 if (unlikely(l >= (sizeof(state_str) - 1))) {
 616                         err = -ENOMEM;
 617                         xenbus_dev_fatal(pdev->xdev, err,
 618                                          "String overflow while reading "
 619                                          "configuration");
 620                         goto out;
 621                 }
 622                 err = xenbus_printf(XBT_NIL, pdev->xdev->nodename, state_str,
 623                                     "%d", XenbusStateInitialised);
 624                 if (err) {
 625                         xenbus_dev_fatal(pdev->xdev, err, "Error switching "
 626                                          "substate of dev-%d\n", i);
 627                         goto out;
 628                 }
 629         }
 630
 631         err = xen_pcibk_publish_pci_roots(pdev, xen_pcibk_publish_pci_root);
 632         if (err) {
 633                 xenbus_dev_fatal(pdev->xdev, err,
 634                                  "Error while publish PCI root buses "
 635                                  "for frontend");
 636                 goto out;
 637         }
 638
 639         err = xenbus_switch_state(pdev->xdev, XenbusStateInitialised);
 640         if (err)
 641                 xenbus_dev_fatal(pdev->xdev, err,
 642                                  "Error switching to initialised state!");
 643
 644 out:
 645         if (!err)
 646                 /* see if pcifront is already configured (if not, we'll wait) */
 647                 xen_pcibk_attach(pdev);
 648
 649         return err;
 650 }
 651
 652 static void xen_pcibk_be_watch(struct xenbus_watch *watch,
 653                              const char **vec, unsigned int len)
 654 {
 655         struct xen_pcibk_device *pdev =
 656             container_of(watch, struct xen_pcibk_device, be_watch);
 657
 658         switch (xenbus_read_driver_state(pdev->xdev->nodename)) {
 659         case XenbusStateInitWait:
 660                 xen_pcibk_setup_backend(pdev);
 661                 break;
 662
 663         default:
 664                 break;
 665         }
 666 }
 667
 668 static int xen_pcibk_xenbus_probe(struct xenbus_device *dev,
 669                                 const struct xenbus_device_id *id)
 670 {
 671         int err = 0;
 672         struct xen_pcibk_device *pdev = alloc_pdev(dev);
 673
 674         if (pdev == NULL) {
 675                 err = -ENOMEM;
 676                 xenbus_dev_fatal(dev, err,
 677                                  "Error allocating xen_pcibk_device struct");
 678                 goto out;
 679         }
 680
 681         /* wait for xend to configure us */
 682         err = xenbus_switch_state(dev, XenbusStateInitWait);
 683         if (err)
 684                 goto out;
 685
 686         /* watch the backend node for backend configuration information */
 687         err = xenbus_watch_path(dev, dev->nodename, &pdev->be_watch,
 688                                 xen_pcibk_be_watch);
 689         if (err)
 690                 goto out;
 691
 692         pdev->be_watching = 1;
 693
 694         /* We need to force a call to our callback here in case
 695          * xend already configured us!
 696          */
 697         xen_pcibk_be_watch(&pdev->be_watch, NULL, 0);
 698
 699 out:
 700         return err;
 701 }
 702
 703 static int xen_pcibk_xenbus_remove(struct xenbus_device *dev)
 704 {
 705         struct xen_pcibk_device *pdev = dev_get_drvdata(&dev->dev);
 706
 707         if (pdev != NULL)
 708                 free_pdev(pdev);
 709
 710         return 0;
 711 }
 712
 713 static const struct xenbus_device_id xenpci_ids[] = {
 714         {"pci"},
 715         {""},
 716 };
 717
 718 static struct xenbus_driver xenbus_xen_pcibk_driver = {
 719         .name                   = DRV_NAME,
 720         .owner                  = THIS_MODULE,
 721         .ids                    = xenpci_ids,
 722         .probe                  = xen_pcibk_xenbus_probe,
 723         .remove                 = xen_pcibk_xenbus_remove,
 724         .otherend_changed       = xen_pcibk_frontend_changed,
 725 };
 726
 727 struct xen_pcibk_backend *xen_pcibk_backend;
 728
 729 int __init xen_pcibk_xenbus_register(void)
 730 {
 731         xen_pcibk_wq = create_workqueue("xen_pciback_workqueue");
 732         if (!xen_pcibk_wq) {
 733                 printk(KERN_ERR "%s: create"
 734                         "xen_pciback_workqueue failed\n", __func__);
 735                 return -EFAULT;
 736         }
 737         xen_pcibk_backend = &xen_pcibk_vpci_backend;
 738         if (passthrough)
 739                 xen_pcibk_backend = &xen_pcibk_passthrough_backend;
 740         pr_info(DRV_NAME ": backend is %s\n", xen_pcibk_backend->name);
 741         return xenbus_register_backend(&xenbus_xen_pcibk_driver);
 742 }
 743
 744 void __exit xen_pcibk_xenbus_unregister(void)
 745 {
 746         destroy_workqueue(xen_pcibk_wq);
 747         xenbus_unregister_driver(&xenbus_xen_pcibk_driver);
 748 }