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_lateeoi(
 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                                  enum xenbus_state state)
 362 {
 363         int err = 0;
 364         int num_devs;
 365         int domain, bus, slot, func;
 366         int substate;
 367         int i, len;
 368         char state_str[64];
 369         char dev_str[64];
 370
 371
 372         dev_dbg(&pdev->xdev->dev, "Reconfiguring device ...\n");
 373
 374         mutex_lock(&pdev->dev_lock);
 375         if (xenbus_read_driver_state(pdev->xdev->nodename) != state)
 376                 goto out;
 377
 378         err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename, "num_devs", "%d",
 379                            &num_devs);
 380         if (err != 1) {
 381                 if (err >= 0)
 382                         err = -EINVAL;
 383                 xenbus_dev_fatal(pdev->xdev, err,
 384                                  "Error reading number of devices");
 385                 goto out;
 386         }
 387
 388         for (i = 0; i < num_devs; i++) {
 389                 len = snprintf(state_str, sizeof(state_str), "state-%d", i);
 390                 if (unlikely(len >= (sizeof(state_str) - 1))) {
 391                         err = -ENOMEM;
 392                         xenbus_dev_fatal(pdev->xdev, err,
 393                                          "String overflow while reading "
 394                                          "configuration");
 395                         goto out;
 396                 }
 397                 err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename, state_str,
 398                                    "%d", &substate);
 399                 if (err != 1)
 400                         substate = XenbusStateUnknown;
 401
 402                 switch (substate) {
 403                 case XenbusStateInitialising:
 404                         dev_dbg(&pdev->xdev->dev, "Attaching dev-%d ...\n", i);
 405
 406                         len = snprintf(dev_str, sizeof(dev_str), "dev-%d", i);
 407                         if (unlikely(len >= (sizeof(dev_str) - 1))) {
 408                                 err = -ENOMEM;
 409                                 xenbus_dev_fatal(pdev->xdev, err,
 410                                                  "String overflow while "
 411                                                  "reading configuration");
 412                                 goto out;
 413                         }
 414                         err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename,
 415                                            dev_str, "%x:%x:%x.%x",
 416                                            &domain, &bus, &slot, &func);
 417                         if (err < 0) {
 418                                 xenbus_dev_fatal(pdev->xdev, err,
 419                                                  "Error reading device "
 420                                                  "configuration");
 421                                 goto out;
 422                         }
 423                         if (err != 4) {
 424                                 err = -EINVAL;
 425                                 xenbus_dev_fatal(pdev->xdev, err,
 426                                                  "Error parsing pci device "
 427                                                  "configuration");
 428                                 goto out;
 429                         }
 430
 431                         err = xen_pcibk_export_device(pdev, domain, bus, slot,
 432                                                     func, i);
 433                         if (err)
 434                                 goto out;
 435
 436                         /* Publish pci roots. */
 437                         err = xen_pcibk_publish_pci_roots(pdev,
 438                                                 xen_pcibk_publish_pci_root);
 439                         if (err) {
 440                                 xenbus_dev_fatal(pdev->xdev, err,
 441                                                  "Error while publish PCI root"
 442                                                  "buses for frontend");
 443                                 goto out;
 444                         }
 445
 446                         err = xenbus_printf(XBT_NIL, pdev->xdev->nodename,
 447                                             state_str, "%d",
 448                                             XenbusStateInitialised);
 449                         if (err) {
 450                                 xenbus_dev_fatal(pdev->xdev, err,
 451                                                  "Error switching substate of "
 452                                                  "dev-%d\n", i);
 453                                 goto out;
 454                         }
 455                         break;
 456
 457                 case XenbusStateClosing:
 458                         dev_dbg(&pdev->xdev->dev, "Detaching dev-%d ...\n", i);
 459
 460                         len = snprintf(dev_str, sizeof(dev_str), "vdev-%d", i);
 461                         if (unlikely(len >= (sizeof(dev_str) - 1))) {
 462                                 err = -ENOMEM;
 463                                 xenbus_dev_fatal(pdev->xdev, err,
 464                                                  "String overflow while "
 465                                                  "reading configuration");
 466                                 goto out;
 467                         }
 468                         err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename,
 469                                            dev_str, "%x:%x:%x.%x",
 470                                            &domain, &bus, &slot, &func);
 471                         if (err < 0) {
 472                                 xenbus_dev_fatal(pdev->xdev, err,
 473                                                  "Error reading device "
 474                                                  "configuration");
 475                                 goto out;
 476                         }
 477                         if (err != 4) {
 478                                 err = -EINVAL;
 479                                 xenbus_dev_fatal(pdev->xdev, err,
 480                                                  "Error parsing pci device "
 481                                                  "configuration");
 482                                 goto out;
 483                         }
 484
 485                         err = xen_pcibk_remove_device(pdev, domain, bus, slot,
 486                                                     func);
 487                         if (err)
 488                                 goto out;
 489
 490                         /* TODO: If at some point we implement support for pci
 491                          * root hot-remove on pcifront side, we'll need to
 492                          * remove unnecessary xenstore nodes of pci roots here.
 493                          */
 494
 495                         break;
 496
 497                 default:
 498                         break;
 499                 }
 500         }
 501
 502         if (state != XenbusStateReconfiguring)
 503                 /* Make sure we only reconfigure once. */
 504                 goto out;
 505
 506         err = xenbus_switch_state(pdev->xdev, XenbusStateReconfigured);
 507         if (err) {
 508                 xenbus_dev_fatal(pdev->xdev, err,
 509                                  "Error switching to reconfigured state!");
 510                 goto out;
 511         }
 512
 513 out:
 514         mutex_unlock(&pdev->dev_lock);
 515         return 0;
 516 }
 517
 518 static void xen_pcibk_frontend_changed(struct xenbus_device *xdev,
 519                                      enum xenbus_state fe_state)
 520 {
 521         struct xen_pcibk_device *pdev = dev_get_drvdata(&xdev->dev);
 522
 523         dev_dbg(&xdev->dev, "fe state changed %d\n", fe_state);
 524
 525         switch (fe_state) {
 526         case XenbusStateInitialised:
 527                 xen_pcibk_attach(pdev);
 528                 break;
 529
 530         case XenbusStateReconfiguring:
 531                 xen_pcibk_reconfigure(pdev, XenbusStateReconfiguring);
 532                 break;
 533
 534         case XenbusStateConnected:
 535                 /* pcifront switched its state from reconfiguring to connected.
 536                  * Then switch to connected state.
 537                  */
 538                 xenbus_switch_state(xdev, XenbusStateConnected);
 539                 break;
 540
 541         case XenbusStateClosing:
 542                 xen_pcibk_disconnect(pdev);
 543                 xenbus_switch_state(xdev, XenbusStateClosing);
 544                 break;
 545
 546         case XenbusStateClosed:
 547                 xen_pcibk_disconnect(pdev);
 548                 xenbus_switch_state(xdev, XenbusStateClosed);
 549                 if (xenbus_dev_is_online(xdev))
 550                         break;
 551                 /* fall through if not online */
 552         case XenbusStateUnknown:
 553                 dev_dbg(&xdev->dev, "frontend is gone! unregister device\n");
 554                 device_unregister(&xdev->dev);
 555                 break;
 556
 557         default:
 558                 break;
 559         }
 560 }
 561
 562 static int xen_pcibk_setup_backend(struct xen_pcibk_device *pdev)
 563 {
 564         /* Get configuration from xend (if available now) */
 565         int domain, bus, slot, func;
 566         int err = 0;
 567         int i, num_devs;
 568         char dev_str[64];
 569         char state_str[64];
 570
 571         mutex_lock(&pdev->dev_lock);
 572         /* It's possible we could get the call to setup twice, so make sure
 573          * we're not already connected.
 574          */
 575         if (xenbus_read_driver_state(pdev->xdev->nodename) !=
 576             XenbusStateInitWait)
 577                 goto out;
 578
 579         dev_dbg(&pdev->xdev->dev, "getting be setup\n");
 580
 581         err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename, "num_devs", "%d",
 582                            &num_devs);
 583         if (err != 1) {
 584                 if (err >= 0)
 585                         err = -EINVAL;
 586                 xenbus_dev_fatal(pdev->xdev, err,
 587                                  "Error reading number of devices");
 588                 goto out;
 589         }
 590
 591         for (i = 0; i < num_devs; i++) {
 592                 int l = snprintf(dev_str, sizeof(dev_str), "dev-%d", i);
 593                 if (unlikely(l >= (sizeof(dev_str) - 1))) {
 594                         err = -ENOMEM;
 595                         xenbus_dev_fatal(pdev->xdev, err,
 596                                          "String overflow while reading "
 597                                          "configuration");
 598                         goto out;
 599                 }
 600
 601                 err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename, dev_str,
 602                                    "%x:%x:%x.%x", &domain, &bus, &slot, &func);
 603                 if (err < 0) {
 604                         xenbus_dev_fatal(pdev->xdev, err,
 605                                          "Error reading device configuration");
 606                         goto out;
 607                 }
 608                 if (err != 4) {
 609                         err = -EINVAL;
 610                         xenbus_dev_fatal(pdev->xdev, err,
 611                                          "Error parsing pci device "
 612                                          "configuration");
 613                         goto out;
 614                 }
 615
 616                 err = xen_pcibk_export_device(pdev, domain, bus, slot, func, i);
 617                 if (err)
 618                         goto out;
 619
 620                 /* Switch substate of this device. */
 621                 l = snprintf(state_str, sizeof(state_str), "state-%d", i);
 622                 if (unlikely(l >= (sizeof(state_str) - 1))) {
 623                         err = -ENOMEM;
 624                         xenbus_dev_fatal(pdev->xdev, err,
 625                                          "String overflow while reading "
 626                                          "configuration");
 627                         goto out;
 628                 }
 629                 err = xenbus_printf(XBT_NIL, pdev->xdev->nodename, state_str,
 630                                     "%d", XenbusStateInitialised);
 631                 if (err) {
 632                         xenbus_dev_fatal(pdev->xdev, err, "Error switching "
 633                                          "substate of dev-%d\n", i);
 634                         goto out;
 635                 }
 636         }
 637
 638         err = xen_pcibk_publish_pci_roots(pdev, xen_pcibk_publish_pci_root);
 639         if (err) {
 640                 xenbus_dev_fatal(pdev->xdev, err,
 641                                  "Error while publish PCI root buses "
 642                                  "for frontend");
 643                 goto out;
 644         }
 645
 646         err = xenbus_switch_state(pdev->xdev, XenbusStateInitialised);
 647         if (err)
 648                 xenbus_dev_fatal(pdev->xdev, err,
 649                                  "Error switching to initialised state!");
 650
 651 out:
 652         mutex_unlock(&pdev->dev_lock);
 653         if (!err)
 654                 /* see if pcifront is already configured (if not, we'll wait) */
 655                 xen_pcibk_attach(pdev);
 656         return err;
 657 }
 658
 659 static void xen_pcibk_be_watch(struct xenbus_watch *watch,
 660                              const char **vec, unsigned int len)
 661 {
 662         struct xen_pcibk_device *pdev =
 663             container_of(watch, struct xen_pcibk_device, be_watch);
 664
 665         switch (xenbus_read_driver_state(pdev->xdev->nodename)) {
 666         case XenbusStateInitWait:
 667                 xen_pcibk_setup_backend(pdev);
 668                 break;
 669
 670         case XenbusStateInitialised:
 671                 /*
 672                  * We typically move to Initialised when the first device was
 673                  * added. Hence subsequent devices getting added may need
 674                  * reconfiguring.
 675                  */
 676                 xen_pcibk_reconfigure(pdev, XenbusStateInitialised);
 677                 break;
 678
 679         default:
 680                 break;
 681         }
 682 }
 683
 684 static int xen_pcibk_xenbus_probe(struct xenbus_device *dev,
 685                                 const struct xenbus_device_id *id)
 686 {
 687         int err = 0;
 688         struct xen_pcibk_device *pdev = alloc_pdev(dev);
 689
 690         if (pdev == NULL) {
 691                 err = -ENOMEM;
 692                 xenbus_dev_fatal(dev, err,
 693                                  "Error allocating xen_pcibk_device struct");
 694                 goto out;
 695         }
 696
 697         /* wait for xend to configure us */
 698         err = xenbus_switch_state(dev, XenbusStateInitWait);
 699         if (err)
 700                 goto out;
 701
 702         /* watch the backend node for backend configuration information */
 703         err = xenbus_watch_path(dev, dev->nodename, &pdev->be_watch,
 704                                 NULL, xen_pcibk_be_watch);
 705         if (err)
 706                 goto out;
 707
 708         pdev->be_watching = 1;
 709
 710         /* We need to force a call to our callback here in case
 711          * xend already configured us!
 712          */
 713         xen_pcibk_be_watch(&pdev->be_watch, NULL, 0);
 714
 715 out:
 716         return err;
 717 }
 718
 719 static int xen_pcibk_xenbus_remove(struct xenbus_device *dev)
 720 {
 721         struct xen_pcibk_device *pdev = dev_get_drvdata(&dev->dev);
 722
 723         if (pdev != NULL)
 724                 free_pdev(pdev);
 725
 726         return 0;
 727 }
 728
 729 static const struct xenbus_device_id xen_pcibk_ids[] = {
 730         {"pci"},
 731         {""},
 732 };
 733
 734 static struct xenbus_driver xen_pcibk_driver = {
 735         .name                   = DRV_NAME,
 736         .ids                    = xen_pcibk_ids,
 737         .probe                  = xen_pcibk_xenbus_probe,
 738         .remove                 = xen_pcibk_xenbus_remove,
 739         .otherend_changed       = xen_pcibk_frontend_changed,
 740 };
 741
 742 const struct xen_pcibk_backend *__read_mostly xen_pcibk_backend;
 743
 744 int __init xen_pcibk_xenbus_register(void)
 745 {
 746         xen_pcibk_backend = &xen_pcibk_vpci_backend;
 747         if (passthrough)
 748                 xen_pcibk_backend = &xen_pcibk_passthrough_backend;
 749         pr_info("backend is %s\n", xen_pcibk_backend->name);
 750         return xenbus_register_backend(&xen_pcibk_driver);
 751 }
 752
 753 void __exit xen_pcibk_xenbus_unregister(void)
 754 {
 755         xenbus_unregister_driver(&xen_pcibk_driver);
 756 }