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                              evtchn_port_t 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=%u\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, 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;
 146         evtchn_port_t remote_evtchn;
 147         char *magic = NULL;
 148
 149
 150         mutex_lock(&pdev->dev_lock);
 151         /* Make sure we only do this setup once */
 152         if (xenbus_read_driver_state(pdev->xdev->nodename) !=
 153             XenbusStateInitialised)
 154                 goto out;
 155
 156         /* Wait for frontend to state that it has published the configuration */
 157         if (xenbus_read_driver_state(pdev->xdev->otherend) !=
 158             XenbusStateInitialised)
 159                 goto out;
 160
 161         dev_dbg(&pdev->xdev->dev, "Reading frontend config\n");
 162
 163         err = xenbus_gather(XBT_NIL, pdev->xdev->otherend,
 164                             "pci-op-ref", "%u", &gnt_ref,
 165                             "event-channel", "%u", &remote_evtchn,
 166                             "magic", NULL, &magic, NULL);
 167         if (err) {
 168                 /* If configuration didn't get read correctly, wait longer */
 169                 xenbus_dev_fatal(pdev->xdev, err,
 170                                  "Error reading configuration from frontend");
 171                 goto out;
 172         }
 173
 174         if (magic == NULL || strcmp(magic, XEN_PCI_MAGIC) != 0) {
 175                 xenbus_dev_fatal(pdev->xdev, -EFAULT,
 176                                  "version mismatch (%s/%s) with pcifront - "
 177                                  "halting " DRV_NAME,
 178                                  magic, XEN_PCI_MAGIC);
 179                 err = -EFAULT;
 180                 goto out;
 181         }
 182
 183         err = xen_pcibk_do_attach(pdev, gnt_ref, remote_evtchn);
 184         if (err)
 185                 goto out;
 186
 187         dev_dbg(&pdev->xdev->dev, "Connecting...\n");
 188
 189         err = xenbus_switch_state(pdev->xdev, XenbusStateConnected);
 190         if (err)
 191                 xenbus_dev_fatal(pdev->xdev, err,
 192                                  "Error switching to connected state!");
 193
 194         dev_dbg(&pdev->xdev->dev, "Connected? %d\n", err);
 195 out:
 196         mutex_unlock(&pdev->dev_lock);
 197
 198         kfree(magic);
 199
 200         return err;
 201 }
 202
 203 static int xen_pcibk_publish_pci_dev(struct xen_pcibk_device *pdev,
 204                                    unsigned int domain, unsigned int bus,
 205                                    unsigned int devfn, unsigned int devid)
 206 {
 207         int err;
 208         int len;
 209         char str[64];
 210
 211         len = snprintf(str, sizeof(str), "vdev-%d", devid);
 212         if (unlikely(len >= (sizeof(str) - 1))) {
 213                 err = -ENOMEM;
 214                 goto out;
 215         }
 216
 217         /* Note: The PV protocol uses %02x, don't change it */
 218         err = xenbus_printf(XBT_NIL, pdev->xdev->nodename, str,
 219                             "%04x:%02x:%02x.%02x", domain, bus,
 220                             PCI_SLOT(devfn), PCI_FUNC(devfn));
 221
 222 out:
 223         return err;
 224 }
 225
 226 static int xen_pcibk_export_device(struct xen_pcibk_device *pdev,
 227                                  int domain, int bus, int slot, int func,
 228                                  int devid)
 229 {
 230         struct pci_dev *dev;
 231         int err = 0;
 232
 233         dev_dbg(&pdev->xdev->dev, "exporting dom %x bus %x slot %x func %x\n",
 234                 domain, bus, slot, func);
 235
 236         dev = pcistub_get_pci_dev_by_slot(pdev, domain, bus, slot, func);
 237         if (!dev) {
 238                 err = -EINVAL;
 239                 xenbus_dev_fatal(pdev->xdev, err,
 240                                  "Couldn't locate PCI device "
 241                                  "(%04x:%02x:%02x.%d)! "
 242                                  "perhaps already in-use?",
 243                                  domain, bus, slot, func);
 244                 goto out;
 245         }
 246
 247         err = xen_pcibk_add_pci_dev(pdev, dev, devid,
 248                                     xen_pcibk_publish_pci_dev);
 249         if (err)
 250                 goto out;
 251
 252         dev_info(&dev->dev, "registering for %d\n", pdev->xdev->otherend_id);
 253         if (xen_register_device_domain_owner(dev,
 254                                              pdev->xdev->otherend_id) != 0) {
 255                 dev_err(&dev->dev, "Stealing ownership from dom%d.\n",
 256                         xen_find_device_domain_owner(dev));
 257                 xen_unregister_device_domain_owner(dev);
 258                 xen_register_device_domain_owner(dev, pdev->xdev->otherend_id);
 259         }
 260
 261         /* TODO: It'd be nice to export a bridge and have all of its children
 262          * get exported with it. This may be best done in xend (which will
 263          * have to calculate resource usage anyway) but we probably want to
 264          * put something in here to ensure that if a bridge gets given to a
 265          * driver domain, that all devices under that bridge are not given
 266          * to other driver domains (as he who controls the bridge can disable
 267          * it and stop the other devices from working).
 268          */
 269 out:
 270         return err;
 271 }
 272
 273 static int xen_pcibk_remove_device(struct xen_pcibk_device *pdev,
 274                                  int domain, int bus, int slot, int func)
 275 {
 276         int err = 0;
 277         struct pci_dev *dev;
 278
 279         dev_dbg(&pdev->xdev->dev, "removing dom %x bus %x slot %x func %x\n",
 280                 domain, bus, slot, func);
 281
 282         dev = xen_pcibk_get_pci_dev(pdev, domain, bus, PCI_DEVFN(slot, func));
 283         if (!dev) {
 284                 err = -EINVAL;
 285                 dev_dbg(&pdev->xdev->dev, "Couldn't locate PCI device "
 286                         "(%04x:%02x:%02x.%d)! not owned by this domain\n",
 287                         domain, bus, slot, func);
 288                 goto out;
 289         }
 290
 291         dev_dbg(&dev->dev, "unregistering for %d\n", pdev->xdev->otherend_id);
 292         xen_unregister_device_domain_owner(dev);
 293
 294         /* N.B. This ends up calling pcistub_put_pci_dev which ends up
 295          * doing the FLR. */
 296         xen_pcibk_release_pci_dev(pdev, dev, true /* use the lock. */);
 297
 298 out:
 299         return err;
 300 }
 301
 302 static int xen_pcibk_publish_pci_root(struct xen_pcibk_device *pdev,
 303                                     unsigned int domain, unsigned int bus)
 304 {
 305         unsigned int d, b;
 306         int i, root_num, len, err;
 307         char str[64];
 308
 309         dev_dbg(&pdev->xdev->dev, "Publishing pci roots\n");
 310
 311         err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename,
 312                            "root_num", "%d", &root_num);
 313         if (err == 0 || err == -ENOENT)
 314                 root_num = 0;
 315         else if (err < 0)
 316                 goto out;
 317
 318         /* Verify that we haven't already published this pci root */
 319         for (i = 0; i < root_num; i++) {
 320                 len = snprintf(str, sizeof(str), "root-%d", i);
 321                 if (unlikely(len >= (sizeof(str) - 1))) {
 322                         err = -ENOMEM;
 323                         goto out;
 324                 }
 325
 326                 err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename,
 327                                    str, "%x:%x", &d, &b);
 328                 if (err < 0)
 329                         goto out;
 330                 if (err != 2) {
 331                         err = -EINVAL;
 332                         goto out;
 333                 }
 334
 335                 if (d == domain && b == bus) {
 336                         err = 0;
 337                         goto out;
 338                 }
 339         }
 340
 341         len = snprintf(str, sizeof(str), "root-%d", root_num);
 342         if (unlikely(len >= (sizeof(str) - 1))) {
 343                 err = -ENOMEM;
 344                 goto out;
 345         }
 346
 347         dev_dbg(&pdev->xdev->dev, "writing root %d at %04x:%02x\n",
 348                 root_num, domain, bus);
 349
 350         err = xenbus_printf(XBT_NIL, pdev->xdev->nodename, str,
 351                             "%04x:%02x", domain, bus);
 352         if (err)
 353                 goto out;
 354
 355         err = xenbus_printf(XBT_NIL, pdev->xdev->nodename,
 356                             "root_num", "%d", (root_num + 1));
 357
 358 out:
 359         return err;
 360 }
 361
 362 static int xen_pcibk_reconfigure(struct xen_pcibk_device *pdev)
 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         /* Make sure we only reconfigure once */
 377         if (xenbus_read_driver_state(pdev->xdev->nodename) !=
 378             XenbusStateReconfiguring)
 379                 goto out;
 380
 381         err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename, "num_devs", "%d",
 382                            &num_devs);
 383         if (err != 1) {
 384                 if (err >= 0)
 385                         err = -EINVAL;
 386                 xenbus_dev_fatal(pdev->xdev, err,
 387                                  "Error reading number of devices");
 388                 goto out;
 389         }
 390
 391         for (i = 0; i < num_devs; i++) {
 392                 len = snprintf(state_str, sizeof(state_str), "state-%d", i);
 393                 if (unlikely(len >= (sizeof(state_str) - 1))) {
 394                         err = -ENOMEM;
 395                         xenbus_dev_fatal(pdev->xdev, err,
 396                                          "String overflow while reading "
 397                                          "configuration");
 398                         goto out;
 399                 }
 400                 substate = xenbus_read_unsigned(pdev->xdev->nodename, state_str,
 401                                                 XenbusStateUnknown);
 402
 403                 switch (substate) {
 404                 case XenbusStateInitialising:
 405                         dev_dbg(&pdev->xdev->dev, "Attaching dev-%d ...\n", i);
 406
 407                         len = snprintf(dev_str, sizeof(dev_str), "dev-%d", i);
 408                         if (unlikely(len >= (sizeof(dev_str) - 1))) {
 409                                 err = -ENOMEM;
 410                                 xenbus_dev_fatal(pdev->xdev, err,
 411                                                  "String overflow while "
 412                                                  "reading configuration");
 413                                 goto out;
 414                         }
 415                         err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename,
 416                                            dev_str, "%x:%x:%x.%x",
 417                                            &domain, &bus, &slot, &func);
 418                         if (err < 0) {
 419                                 xenbus_dev_fatal(pdev->xdev, err,
 420                                                  "Error reading device "
 421                                                  "configuration");
 422                                 goto out;
 423                         }
 424                         if (err != 4) {
 425                                 err = -EINVAL;
 426                                 xenbus_dev_fatal(pdev->xdev, err,
 427                                                  "Error parsing pci device "
 428                                                  "configuration");
 429                                 goto out;
 430                         }
 431
 432                         err = xen_pcibk_export_device(pdev, domain, bus, slot,
 433                                                     func, i);
 434                         if (err)
 435                                 goto out;
 436
 437                         /* Publish pci roots. */
 438                         err = xen_pcibk_publish_pci_roots(pdev,
 439                                                 xen_pcibk_publish_pci_root);
 440                         if (err) {
 441                                 xenbus_dev_fatal(pdev->xdev, err,
 442                                                  "Error while publish PCI root"
 443                                                  "buses for frontend");
 444                                 goto out;
 445                         }
 446
 447                         err = xenbus_printf(XBT_NIL, pdev->xdev->nodename,
 448                                             state_str, "%d",
 449                                             XenbusStateInitialised);
 450                         if (err) {
 451                                 xenbus_dev_fatal(pdev->xdev, err,
 452                                                  "Error switching substate of "
 453                                                  "dev-%d\n", i);
 454                                 goto out;
 455                         }
 456                         break;
 457
 458                 case XenbusStateClosing:
 459                         dev_dbg(&pdev->xdev->dev, "Detaching dev-%d ...\n", i);
 460
 461                         len = snprintf(dev_str, sizeof(dev_str), "vdev-%d", i);
 462                         if (unlikely(len >= (sizeof(dev_str) - 1))) {
 463                                 err = -ENOMEM;
 464                                 xenbus_dev_fatal(pdev->xdev, err,
 465                                                  "String overflow while "
 466                                                  "reading configuration");
 467                                 goto out;
 468                         }
 469                         err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename,
 470                                            dev_str, "%x:%x:%x.%x",
 471                                            &domain, &bus, &slot, &func);
 472                         if (err < 0) {
 473                                 xenbus_dev_fatal(pdev->xdev, err,
 474                                                  "Error reading device "
 475                                                  "configuration");
 476                                 goto out;
 477                         }
 478                         if (err != 4) {
 479                                 err = -EINVAL;
 480                                 xenbus_dev_fatal(pdev->xdev, err,
 481                                                  "Error parsing pci device "
 482                                                  "configuration");
 483                                 goto out;
 484                         }
 485
 486                         err = xen_pcibk_remove_device(pdev, domain, bus, slot,
 487                                                     func);
 488                         if (err)
 489                                 goto out;
 490
 491                         /* TODO: If at some point we implement support for pci
 492                          * root hot-remove on pcifront side, we'll need to
 493                          * remove unnecessary xenstore nodes of pci roots here.
 494                          */
 495
 496                         break;
 497
 498                 default:
 499                         break;
 500                 }
 501         }
 502
 503         err = xenbus_switch_state(pdev->xdev, XenbusStateReconfigured);
 504         if (err) {
 505                 xenbus_dev_fatal(pdev->xdev, err,
 506                                  "Error switching to reconfigured state!");
 507                 goto out;
 508         }
 509
 510 out:
 511         mutex_unlock(&pdev->dev_lock);
 512         return 0;
 513 }
 514
 515 static void xen_pcibk_frontend_changed(struct xenbus_device *xdev,
 516                                      enum xenbus_state fe_state)
 517 {
 518         struct xen_pcibk_device *pdev = dev_get_drvdata(&xdev->dev);
 519
 520         dev_dbg(&xdev->dev, "fe state changed %d\n", fe_state);
 521
 522         switch (fe_state) {
 523         case XenbusStateInitialised:
 524                 xen_pcibk_attach(pdev);
 525                 break;
 526
 527         case XenbusStateReconfiguring:
 528                 xen_pcibk_reconfigure(pdev);
 529                 break;
 530
 531         case XenbusStateConnected:
 532                 /* pcifront switched its state from reconfiguring to connected.
 533                  * Then switch to connected state.
 534                  */
 535                 xenbus_switch_state(xdev, XenbusStateConnected);
 536                 break;
 537
 538         case XenbusStateClosing:
 539                 xen_pcibk_disconnect(pdev);
 540                 xenbus_switch_state(xdev, XenbusStateClosing);
 541                 break;
 542
 543         case XenbusStateClosed:
 544                 xen_pcibk_disconnect(pdev);
 545                 xenbus_switch_state(xdev, XenbusStateClosed);
 546                 if (xenbus_dev_is_online(xdev))
 547                         break;
 548                 fallthrough;    /* if not online */
 549         case XenbusStateUnknown:
 550                 dev_dbg(&xdev->dev, "frontend is gone! unregister device\n");
 551                 device_unregister(&xdev->dev);
 552                 break;
 553
 554         default:
 555                 break;
 556         }
 557 }
 558
 559 static int xen_pcibk_setup_backend(struct xen_pcibk_device *pdev)
 560 {
 561         /* Get configuration from xend (if available now) */
 562         int domain, bus, slot, func;
 563         int err = 0;
 564         int i, num_devs;
 565         char dev_str[64];
 566         char state_str[64];
 567
 568         mutex_lock(&pdev->dev_lock);
 569         /* It's possible we could get the call to setup twice, so make sure
 570          * we're not already connected.
 571          */
 572         if (xenbus_read_driver_state(pdev->xdev->nodename) !=
 573             XenbusStateInitWait)
 574                 goto out;
 575
 576         dev_dbg(&pdev->xdev->dev, "getting be setup\n");
 577
 578         err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename, "num_devs", "%d",
 579                            &num_devs);
 580         if (err != 1) {
 581                 if (err >= 0)
 582                         err = -EINVAL;
 583                 xenbus_dev_fatal(pdev->xdev, err,
 584                                  "Error reading number of devices");
 585                 goto out;
 586         }
 587
 588         for (i = 0; i < num_devs; i++) {
 589                 int l = snprintf(dev_str, sizeof(dev_str), "dev-%d", i);
 590                 if (unlikely(l >= (sizeof(dev_str) - 1))) {
 591                         err = -ENOMEM;
 592                         xenbus_dev_fatal(pdev->xdev, err,
 593                                          "String overflow while reading "
 594                                          "configuration");
 595                         goto out;
 596                 }
 597
 598                 err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename, dev_str,
 599                                    "%x:%x:%x.%x", &domain, &bus, &slot, &func);
 600                 if (err < 0) {
 601                         xenbus_dev_fatal(pdev->xdev, err,
 602                                          "Error reading device configuration");
 603                         goto out;
 604                 }
 605                 if (err != 4) {
 606                         err = -EINVAL;
 607                         xenbus_dev_fatal(pdev->xdev, err,
 608                                          "Error parsing pci device "
 609                                          "configuration");
 610                         goto out;
 611                 }
 612
 613                 err = xen_pcibk_export_device(pdev, domain, bus, slot, func, i);
 614                 if (err)
 615                         goto out;
 616
 617                 /* Switch substate of this device. */
 618                 l = snprintf(state_str, sizeof(state_str), "state-%d", i);
 619                 if (unlikely(l >= (sizeof(state_str) - 1))) {
 620                         err = -ENOMEM;
 621                         xenbus_dev_fatal(pdev->xdev, err,
 622                                          "String overflow while reading "
 623                                          "configuration");
 624                         goto out;
 625                 }
 626                 err = xenbus_printf(XBT_NIL, pdev->xdev->nodename, state_str,
 627                                     "%d", XenbusStateInitialised);
 628                 if (err) {
 629                         xenbus_dev_fatal(pdev->xdev, err, "Error switching "
 630                                          "substate of dev-%d\n", i);
 631                         goto out;
 632                 }
 633         }
 634
 635         err = xen_pcibk_publish_pci_roots(pdev, xen_pcibk_publish_pci_root);
 636         if (err) {
 637                 xenbus_dev_fatal(pdev->xdev, err,
 638                                  "Error while publish PCI root buses "
 639                                  "for frontend");
 640                 goto out;
 641         }
 642
 643         err = xenbus_switch_state(pdev->xdev, XenbusStateInitialised);
 644         if (err)
 645                 xenbus_dev_fatal(pdev->xdev, err,
 646                                  "Error switching to initialised state!");
 647
 648 out:
 649         mutex_unlock(&pdev->dev_lock);
 650         if (!err)
 651                 /* see if pcifront is already configured (if not, we'll wait) */
 652                 xen_pcibk_attach(pdev);
 653         return err;
 654 }
 655
 656 static void xen_pcibk_be_watch(struct xenbus_watch *watch,
 657                                const char *path, const char *token)
 658 {
 659         struct xen_pcibk_device *pdev =
 660             container_of(watch, struct xen_pcibk_device, be_watch);
 661
 662         switch (xenbus_read_driver_state(pdev->xdev->nodename)) {
 663         case XenbusStateInitWait:
 664                 xen_pcibk_setup_backend(pdev);
 665                 break;
 666
 667         default:
 668                 break;
 669         }
 670 }
 671
 672 static int xen_pcibk_xenbus_probe(struct xenbus_device *dev,
 673                                 const struct xenbus_device_id *id)
 674 {
 675         int err = 0;
 676         struct xen_pcibk_device *pdev = alloc_pdev(dev);
 677
 678         if (pdev == NULL) {
 679                 err = -ENOMEM;
 680                 xenbus_dev_fatal(dev, err,
 681                                  "Error allocating xen_pcibk_device struct");
 682                 goto out;
 683         }
 684
 685         /* wait for xend to configure us */
 686         err = xenbus_switch_state(dev, XenbusStateInitWait);
 687         if (err)
 688                 goto out;
 689
 690         /* watch the backend node for backend configuration information */
 691         err = xenbus_watch_path(dev, dev->nodename, &pdev->be_watch,
 692                                 NULL, xen_pcibk_be_watch);
 693         if (err)
 694                 goto out;
 695
 696         pdev->be_watching = 1;
 697
 698         /* We need to force a call to our callback here in case
 699          * xend already configured us!
 700          */
 701         xen_pcibk_be_watch(&pdev->be_watch, NULL, NULL);
 702
 703 out:
 704         return err;
 705 }
 706
 707 static int xen_pcibk_xenbus_remove(struct xenbus_device *dev)
 708 {
 709         struct xen_pcibk_device *pdev = dev_get_drvdata(&dev->dev);
 710
 711         if (pdev != NULL)
 712                 free_pdev(pdev);
 713
 714         return 0;
 715 }
 716
 717 static const struct xenbus_device_id xen_pcibk_ids[] = {
 718         {"pci"},
 719         {""},
 720 };
 721
 722 static struct xenbus_driver xen_pcibk_driver = {
 723         .name                   = DRV_NAME,
 724         .ids                    = xen_pcibk_ids,
 725         .probe                  = xen_pcibk_xenbus_probe,
 726         .remove                 = xen_pcibk_xenbus_remove,
 727         .otherend_changed       = xen_pcibk_frontend_changed,
 728 };
 729
 730 const struct xen_pcibk_backend *__read_mostly xen_pcibk_backend;
 731
 732 int __init xen_pcibk_xenbus_register(void)
 733 {
 734         xen_pcibk_backend = &xen_pcibk_vpci_backend;
 735         if (passthrough)
 736                 xen_pcibk_backend = &xen_pcibk_passthrough_backend;
 737         pr_info("backend is %s\n", xen_pcibk_backend->name);
 738         return xenbus_register_backend(&xen_pcibk_driver);
 739 }
 740
 741 void __exit xen_pcibk_xenbus_unregister(void)
 742 {
 743         xenbus_unregister_driver(&xen_pcibk_driver);
 744 }