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