drivers/xen/xen-pciback/xenbus.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * PCI Backend Xenbus Setup - handles setup with frontend and xend
   4  *
   5  *   Author: Ryan Wilson <hap9@epoch.ncsc.mil>
   6  */
   7
   8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
   9
  10 #include <linux/moduleparam.h>
  11 #include <linux/init.h>
  12 #include <linux/list.h>
  13 #include <linux/vmalloc.h>
  14 #include <linux/workqueue.h>
  15 #include <xen/xenbus.h>
  16 #include <xen/events.h>
  17 #include <asm/xen/pci.h>
  18 #include "pciback.h"
  19
  20 #define INVALID_EVTCHN_IRQ  (-1)
  21
  22 static bool __read_mostly passthrough;
  23 module_param(passthrough, bool, S_IRUGO);
  24 MODULE_PARM_DESC(passthrough,
  25         "Option to specify how to export PCI topology to guest:\n"\
  26         " 0 - (default) Hide the true PCI topology and makes the frontend\n"\
  27         "   there is a single PCI bus with only the exported devices on it.\n"\
  28         "   For example, a device at 03:05.0 will be re-assigned to 00:00.0\n"\
  29         "   while second device at 02:1a.1 will be re-assigned to 00:01.1.\n"\
  30         " 1 - Passthrough provides a real view of the PCI topology to the\n"\
  31         "   frontend (for example, a device at 06:01.b will still appear at\n"\
  32         "   06:01.b to the frontend). This is similar to how Xen 2.0.x\n"\
  33         "   exposed PCI devices to its driver domains. This may be required\n"\
  34         "   for drivers which depend on finding their hardward in certain\n"\
  35         "   bus/slot locations.");
  36
  37 static struct xen_pcibk_device *alloc_pdev(struct xenbus_device *xdev)
  38 {
  39         struct xen_pcibk_device *pdev;
  40
  41         pdev = kzalloc(sizeof(struct xen_pcibk_device), GFP_KERNEL);
  42         if (pdev == NULL)
  43                 goto out;
  44         dev_dbg(&xdev->dev, "allocated pdev @ 0x%p\n", pdev);
  45
  46         pdev->xdev = xdev;
  47
  48         mutex_init(&pdev->dev_lock);
  49
  50         pdev->sh_info = NULL;
  51         pdev->evtchn_irq = INVALID_EVTCHN_IRQ;
  52         pdev->be_watching = 0;
  53
  54         INIT_WORK(&pdev->op_work, xen_pcibk_do_op);
  55
  56         if (xen_pcibk_init_devices(pdev)) {
  57                 kfree(pdev);
  58                 pdev = NULL;
  59         }
  60
  61         dev_set_drvdata(&xdev->dev, pdev);
  62
  63 out:
  64         return pdev;
  65 }
  66
  67 static void xen_pcibk_disconnect(struct xen_pcibk_device *pdev)
  68 {
  69         mutex_lock(&pdev->dev_lock);
  70         /* Ensure the guest can't trigger our handler before removing devices */
  71         if (pdev->evtchn_irq != INVALID_EVTCHN_IRQ) {
  72                 unbind_from_irqhandler(pdev->evtchn_irq, pdev);
  73                 pdev->evtchn_irq = INVALID_EVTCHN_IRQ;
  74         }
  75
  76         /* If the driver domain started an op, make sure we complete it
  77          * before releasing the shared memory */
  78
  79         flush_work(&pdev->op_work);
  80
  81         if (pdev->sh_info != NULL) {
  82                 xenbus_unmap_ring_vfree(pdev->xdev, pdev->sh_info);
  83                 pdev->sh_info = NULL;
  84         }
  85         mutex_unlock(&pdev->dev_lock);
  86 }
  87
  88 static void free_pdev(struct xen_pcibk_device *pdev)
  89 {
  90         if (pdev->be_watching) {
  91                 unregister_xenbus_watch(&pdev->be_watch);
  92                 pdev->be_watching = 0;
  93         }
  94
  95         xen_pcibk_disconnect(pdev);
  96
  97         /* N.B. This calls pcistub_put_pci_dev which does the FLR on all
  98          * of the PCIe devices. */
  99         xen_pcibk_release_devices(pdev);
 100
 101         dev_set_drvdata(&pdev->xdev->dev, NULL);
 102         pdev->xdev = NULL;
 103
 104         kfree(pdev);
 105 }
 106
 107 static int xen_pcibk_do_attach(struct xen_pcibk_device *pdev, int gnt_ref,
 108                              int remote_evtchn)
 109 {
 110         int err = 0;
 111         void *vaddr;
 112
 113         dev_dbg(&pdev->xdev->dev,
 114                 "Attaching to frontend resources - gnt_ref=%d evtchn=%d\n",
 115                 gnt_ref, remote_evtchn);
 116
 117         err = xenbus_map_ring_valloc(pdev->xdev, &gnt_ref, 1, &vaddr);
 118         if (err < 0) {
 119                 xenbus_dev_fatal(pdev->xdev, err,
 120                                 "Error mapping other domain page in ours.");
 121                 goto out;
 122         }
 123
 124         pdev->sh_info = vaddr;
 125
 126         err = bind_interdomain_evtchn_to_irqhandler_lateeoi(
 127                 pdev->xdev->otherend_id, remote_evtchn, xen_pcibk_handle_event,
 128                 0, DRV_NAME, pdev);
 129         if (err < 0) {
 130                 xenbus_dev_fatal(pdev->xdev, err,
 131                                  "Error binding event channel to IRQ");
 132                 goto out;
 133         }
 134         pdev->evtchn_irq = err;
 135         err = 0;
 136
 137         dev_dbg(&pdev->xdev->dev, "Attached!\n");
 138 out:
 139         return err;
 140 }
 141
 142 static int xen_pcibk_attach(struct xen_pcibk_device *pdev)
 143 {
 144         int err = 0;
 145         int gnt_ref, remote_evtchn;
 146         char *magic = NULL;
 147
 148
 149         mutex_lock(&pdev->dev_lock);
 150         /* Make sure we only do this setup once */
 151         if (xenbus_read_driver_state(pdev->xdev->nodename) !=
 152             XenbusStateInitialised)
 153                 goto out;
 154
 155         /* Wait for frontend to state that it has published the configuration */
 156         if (xenbus_read_driver_state(pdev->xdev->otherend) !=
 157             XenbusStateInitialised)
 158                 goto out;
 159
 160         dev_dbg(&pdev->xdev->dev, "Reading frontend config\n");
 161
 162         err = xenbus_gather(XBT_NIL, pdev->xdev->otherend,
 163                             "pci-op-ref", "%u", &gnt_ref,
 164                             "event-channel", "%u", &remote_evtchn,
 165                             "magic", NULL, &magic, NULL);
 166         if (err) {
 167                 /* If configuration didn't get read correctly, wait longer */
 168                 xenbus_dev_fatal(pdev->xdev, err,
 169                                  "Error reading configuration from frontend");
 170                 goto out;
 171         }
 172
 173         if (magic == NULL || strcmp(magic, XEN_PCI_MAGIC) != 0) {
 174                 xenbus_dev_fatal(pdev->xdev, -EFAULT,
 175                                  "version mismatch (%s/%s) with pcifront - "
 176                                  "halting " DRV_NAME,
 177                                  magic, XEN_PCI_MAGIC);
 178                 err = -EFAULT;
 179                 goto out;
 180         }
 181
 182         err = xen_pcibk_do_attach(pdev, gnt_ref, remote_evtchn);
 183         if (err)
 184                 goto out;
 185
 186         dev_dbg(&pdev->xdev->dev, "Connecting...\n");
 187
 188         err = xenbus_switch_state(pdev->xdev, XenbusStateConnected);
 189         if (err)
 190                 xenbus_dev_fatal(pdev->xdev, err,
 191                                  "Error switching to connected state!");
 192
 193         dev_dbg(&pdev->xdev->dev, "Connected? %d\n", err);
 194 out:
 195         mutex_unlock(&pdev->dev_lock);
 196
 197         kfree(magic);
 198
 199         return err;
 200 }
 201
 202 static int xen_pcibk_publish_pci_dev(struct xen_pcibk_device *pdev,
 203                                    unsigned int domain, unsigned int bus,
 204                                    unsigned int devfn, unsigned int devid)
 205 {
 206         int err;
 207         int len;
 208         char str[64];
 209
 210         len = snprintf(str, sizeof(str), "vdev-%d", devid);
 211         if (unlikely(len >= (sizeof(str) - 1))) {
 212                 err = -ENOMEM;
 213                 goto out;
 214         }
 215
 216         /* Note: The PV protocol uses %02x, don't change it */
 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.%d)! "
 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_info(&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, "Stealing ownership from dom%d.\n",
 255                         xen_find_device_domain_owner(dev));
 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.%d)! 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         /* N.B. This ends up calling pcistub_put_pci_dev which ends up
 294          * doing the FLR. */
 295         xen_pcibk_release_pci_dev(pdev, dev, true /* use the lock. */);
 296
 297 out:
 298         return err;
 299 }
 300
 301 static int xen_pcibk_publish_pci_root(struct xen_pcibk_device *pdev,
 302                                     unsigned int domain, unsigned int bus)
 303 {
 304         unsigned int d, b;
 305         int i, root_num, len, err;
 306         char str[64];
 307
 308         dev_dbg(&pdev->xdev->dev, "Publishing pci roots\n");
 309
 310         err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename,
 311                            "root_num", "%d", &root_num);
 312         if (err == 0 || err == -ENOENT)
 313                 root_num = 0;
 314         else if (err < 0)
 315                 goto out;
 316
 317         /* Verify that we haven't already published this pci root */
 318         for (i = 0; i < root_num; i++) {
 319                 len = snprintf(str, sizeof(str), "root-%d", i);
 320                 if (unlikely(len >= (sizeof(str) - 1))) {
 321                         err = -ENOMEM;
 322                         goto out;
 323                 }
 324
 325                 err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename,
 326                                    str, "%x:%x", &d, &b);
 327                 if (err < 0)
 328                         goto out;
 329                 if (err != 2) {
 330                         err = -EINVAL;
 331                         goto out;
 332                 }
 333
 334                 if (d == domain && b == bus) {
 335                         err = 0;
 336                         goto out;
 337                 }
 338         }
 339
 340         len = snprintf(str, sizeof(str), "root-%d", root_num);
 341         if (unlikely(len >= (sizeof(str) - 1))) {
 342                 err = -ENOMEM;
 343                 goto out;
 344         }
 345
 346         dev_dbg(&pdev->xdev->dev, "writing root %d at %04x:%02x\n",
 347                 root_num, domain, bus);
 348
 349         err = xenbus_printf(XBT_NIL, pdev->xdev->nodename, str,
 350                             "%04x:%02x", domain, bus);
 351         if (err)
 352                 goto out;
 353
 354         err = xenbus_printf(XBT_NIL, pdev->xdev->nodename,
 355                             "root_num", "%d", (root_num + 1));
 356
 357 out:
 358         return err;
 359 }
 360
 361 static int xen_pcibk_reconfigure(struct xen_pcibk_device *pdev,
 362                                  enum xenbus_state state)
 363 {
 364         int err = 0;
 365         int num_devs;
 366         int domain, bus, slot, func;
 367         unsigned int substate;
 368         int i, len;
 369         char state_str[64];
 370         char dev_str[64];
 371
 372
 373         dev_dbg(&pdev->xdev->dev, "Reconfiguring device ...\n");
 374
 375         mutex_lock(&pdev->dev_lock);
 376         if (xenbus_read_driver_state(pdev->xdev->nodename) != state)
 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         if (state != XenbusStateReconfiguring)
 502                 /* Make sure we only reconfigure once. */
 503                 goto out;
 504
 505         err = xenbus_switch_state(pdev->xdev, XenbusStateReconfigured);
 506         if (err) {
 507                 xenbus_dev_fatal(pdev->xdev, err,
 508                                  "Error switching to reconfigured state!");
 509                 goto out;
 510         }
 511
 512 out:
 513         mutex_unlock(&pdev->dev_lock);
 514         return 0;
 515 }
 516
 517 static void xen_pcibk_frontend_changed(struct xenbus_device *xdev,
 518                                      enum xenbus_state fe_state)
 519 {
 520         struct xen_pcibk_device *pdev = dev_get_drvdata(&xdev->dev);
 521
 522         dev_dbg(&xdev->dev, "fe state changed %d\n", fe_state);
 523
 524         switch (fe_state) {
 525         case XenbusStateInitialised:
 526                 xen_pcibk_attach(pdev);
 527                 break;
 528
 529         case XenbusStateReconfiguring:
 530                 xen_pcibk_reconfigure(pdev, XenbusStateReconfiguring);
 531                 break;
 532
 533         case XenbusStateConnected:
 534                 /* pcifront switched its state from reconfiguring to connected.
 535                  * Then switch to connected state.
 536                  */
 537                 xenbus_switch_state(xdev, XenbusStateConnected);
 538                 break;
 539
 540         case XenbusStateClosing:
 541                 xen_pcibk_disconnect(pdev);
 542                 xenbus_switch_state(xdev, XenbusStateClosing);
 543                 break;
 544
 545         case XenbusStateClosed:
 546                 xen_pcibk_disconnect(pdev);
 547                 xenbus_switch_state(xdev, XenbusStateClosed);
 548                 if (xenbus_dev_is_online(xdev))
 549                         break;
 550                 /* fall through if not online */
 551         case XenbusStateUnknown:
 552                 dev_dbg(&xdev->dev, "frontend is gone! unregister device\n");
 553                 device_unregister(&xdev->dev);
 554                 break;
 555
 556         default:
 557                 break;
 558         }
 559 }
 560
 561 static int xen_pcibk_setup_backend(struct xen_pcibk_device *pdev)
 562 {
 563         /* Get configuration from xend (if available now) */
 564         int domain, bus, slot, func;
 565         int err = 0;
 566         int i, num_devs;
 567         char dev_str[64];
 568         char state_str[64];
 569
 570         mutex_lock(&pdev->dev_lock);
 571         /* It's possible we could get the call to setup twice, so make sure
 572          * we're not already connected.
 573          */
 574         if (xenbus_read_driver_state(pdev->xdev->nodename) !=
 575             XenbusStateInitWait)
 576                 goto out;
 577
 578         dev_dbg(&pdev->xdev->dev, "getting be setup\n");
 579
 580         err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename, "num_devs", "%d",
 581                            &num_devs);
 582         if (err != 1) {
 583                 if (err >= 0)
 584                         err = -EINVAL;
 585                 xenbus_dev_fatal(pdev->xdev, err,
 586                                  "Error reading number of devices");
 587                 goto out;
 588         }
 589
 590         for (i = 0; i < num_devs; i++) {
 591                 int l = snprintf(dev_str, sizeof(dev_str), "dev-%d", i);
 592                 if (unlikely(l >= (sizeof(dev_str) - 1))) {
 593                         err = -ENOMEM;
 594                         xenbus_dev_fatal(pdev->xdev, err,
 595                                          "String overflow while reading "
 596                                          "configuration");
 597                         goto out;
 598                 }
 599
 600                 err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename, dev_str,
 601                                    "%x:%x:%x.%x", &domain, &bus, &slot, &func);
 602                 if (err < 0) {
 603                         xenbus_dev_fatal(pdev->xdev, err,
 604                                          "Error reading device configuration");
 605                         goto out;
 606                 }
 607                 if (err != 4) {
 608                         err = -EINVAL;
 609                         xenbus_dev_fatal(pdev->xdev, err,
 610                                          "Error parsing pci device "
 611                                          "configuration");
 612                         goto out;
 613                 }
 614
 615                 err = xen_pcibk_export_device(pdev, domain, bus, slot, func, i);
 616                 if (err)
 617                         goto out;
 618
 619                 /* Switch substate of this device. */
 620                 l = snprintf(state_str, sizeof(state_str), "state-%d", i);
 621                 if (unlikely(l >= (sizeof(state_str) - 1))) {
 622                         err = -ENOMEM;
 623                         xenbus_dev_fatal(pdev->xdev, err,
 624                                          "String overflow while reading "
 625                                          "configuration");
 626                         goto out;
 627                 }
 628                 err = xenbus_printf(XBT_NIL, pdev->xdev->nodename, state_str,
 629                                     "%d", XenbusStateInitialised);
 630                 if (err) {
 631                         xenbus_dev_fatal(pdev->xdev, err, "Error switching "
 632                                          "substate of dev-%d\n", i);
 633                         goto out;
 634                 }
 635         }
 636
 637         err = xen_pcibk_publish_pci_roots(pdev, xen_pcibk_publish_pci_root);
 638         if (err) {
 639                 xenbus_dev_fatal(pdev->xdev, err,
 640                                  "Error while publish PCI root buses "
 641                                  "for frontend");
 642                 goto out;
 643         }
 644
 645         err = xenbus_switch_state(pdev->xdev, XenbusStateInitialised);
 646         if (err)
 647                 xenbus_dev_fatal(pdev->xdev, err,
 648                                  "Error switching to initialised state!");
 649
 650 out:
 651         mutex_unlock(&pdev->dev_lock);
 652         if (!err)
 653                 /* see if pcifront is already configured (if not, we'll wait) */
 654                 xen_pcibk_attach(pdev);
 655         return err;
 656 }
 657
 658 static void xen_pcibk_be_watch(struct xenbus_watch *watch,
 659                                const char *path, const char *token)
 660 {
 661         struct xen_pcibk_device *pdev =
 662             container_of(watch, struct xen_pcibk_device, be_watch);
 663
 664         switch (xenbus_read_driver_state(pdev->xdev->nodename)) {
 665         case XenbusStateInitWait:
 666                 xen_pcibk_setup_backend(pdev);
 667                 break;
 668
 669         case XenbusStateInitialised:
 670                 /*
 671                  * We typically move to Initialised when the first device was
 672                  * added. Hence subsequent devices getting added may need
 673                  * reconfiguring.
 674                  */
 675                 xen_pcibk_reconfigure(pdev, XenbusStateInitialised);
 676                 break;
 677
 678         default:
 679                 break;
 680         }
 681 }
 682
 683 static int xen_pcibk_xenbus_probe(struct xenbus_device *dev,
 684                                 const struct xenbus_device_id *id)
 685 {
 686         int err = 0;
 687         struct xen_pcibk_device *pdev = alloc_pdev(dev);
 688
 689         if (pdev == NULL) {
 690                 err = -ENOMEM;
 691                 xenbus_dev_fatal(dev, err,
 692                                  "Error allocating xen_pcibk_device struct");
 693                 goto out;
 694         }
 695
 696         /* wait for xend to configure us */
 697         err = xenbus_switch_state(dev, XenbusStateInitWait);
 698         if (err)
 699                 goto out;
 700
 701         /* watch the backend node for backend configuration information */
 702         err = xenbus_watch_path(dev, dev->nodename, &pdev->be_watch,
 703                                 NULL, xen_pcibk_be_watch);
 704         if (err)
 705                 goto out;
 706
 707         pdev->be_watching = 1;
 708
 709         /* We need to force a call to our callback here in case
 710          * xend already configured us!
 711          */
 712         xen_pcibk_be_watch(&pdev->be_watch, NULL, 0);
 713
 714 out:
 715         return err;
 716 }
 717
 718 static int xen_pcibk_xenbus_remove(struct xenbus_device *dev)
 719 {
 720         struct xen_pcibk_device *pdev = dev_get_drvdata(&dev->dev);
 721
 722         if (pdev != NULL)
 723                 free_pdev(pdev);
 724
 725         return 0;
 726 }
 727
 728 static const struct xenbus_device_id xen_pcibk_ids[] = {
 729         {"pci"},
 730         {""},
 731 };
 732
 733 static struct xenbus_driver xen_pcibk_driver = {
 734         .name                   = DRV_NAME,
 735         .ids                    = xen_pcibk_ids,
 736         .probe                  = xen_pcibk_xenbus_probe,
 737         .remove                 = xen_pcibk_xenbus_remove,
 738         .otherend_changed       = xen_pcibk_frontend_changed,
 739 };
 740
 741 const struct xen_pcibk_backend *__read_mostly xen_pcibk_backend;
 742
 743 int __init xen_pcibk_xenbus_register(void)
 744 {
 745         xen_pcibk_backend = &xen_pcibk_vpci_backend;
 746         if (passthrough)
 747                 xen_pcibk_backend = &xen_pcibk_passthrough_backend;
 748         pr_info("backend is %s\n", xen_pcibk_backend->name);
 749         return xenbus_register_backend(&xen_pcibk_driver);
 750 }
 751
 752 void __exit xen_pcibk_xenbus_unregister(void)
 753 {
 754         xenbus_unregister_driver(&xen_pcibk_driver);
 755 }