kernel/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/module.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 struct workqueue_struct *xen_pcibk_wq;
  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         /* Note, the workqueue does not use spinlocks at all.*/
  80         flush_workqueue(xen_pcibk_wq);
  81
  82         if (pdev->sh_info != NULL) {
  83                 xenbus_unmap_ring_vfree(pdev->xdev, pdev->sh_info);
  84                 pdev->sh_info = NULL;
  85         }
  86         mutex_unlock(&pdev->dev_lock);
  87 }
  88
  89 static void free_pdev(struct xen_pcibk_device *pdev)
  90 {
  91         if (pdev->be_watching) {
  92                 unregister_xenbus_watch(&pdev->be_watch);
  93                 pdev->be_watching = 0;
  94         }
  95
  96         xen_pcibk_disconnect(pdev);
  97
  98         /* N.B. This calls pcistub_put_pci_dev which does the FLR on all
  99          * of the PCIe devices. */
 100         xen_pcibk_release_devices(pdev);
 101
 102         dev_set_drvdata(&pdev->xdev->dev, NULL);
 103         pdev->xdev = NULL;
 104
 105         kfree(pdev);
 106 }
 107
 108 static int xen_pcibk_do_attach(struct xen_pcibk_device *pdev, int gnt_ref,
 109                              int remote_evtchn)
 110 {
 111         int err = 0;
 112         void *vaddr;
 113
 114         dev_dbg(&pdev->xdev->dev,
 115                 "Attaching to frontend resources - gnt_ref=%d evtchn=%d\n",
 116                 gnt_ref, remote_evtchn);
 117
 118         err = xenbus_map_ring_valloc(pdev->xdev, &gnt_ref, 1, &vaddr);
 119         if (err < 0) {
 120                 xenbus_dev_fatal(pdev->xdev, err,
 121                                 "Error mapping other domain page in ours.");
 122                 goto out;
 123         }
 124
 125         pdev->sh_info = vaddr;
 126
 127         err = bind_interdomain_evtchn_to_irqhandler(
 128                 pdev->xdev->otherend_id, remote_evtchn, xen_pcibk_handle_event,
 129                 0, DRV_NAME, pdev);
 130         if (err < 0) {
 131                 xenbus_dev_fatal(pdev->xdev, err,
 132                                  "Error binding event channel to IRQ");
 133                 goto out;
 134         }
 135         pdev->evtchn_irq = err;
 136         err = 0;
 137
 138         dev_dbg(&pdev->xdev->dev, "Attached!\n");
 139 out:
 140         return err;
 141 }
 142
 143 static int xen_pcibk_attach(struct xen_pcibk_device *pdev)
 144 {
 145         int err = 0;
 146         int gnt_ref, 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         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                 err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename, state_str,
 401                                    "%d", &substate);
 402                 if (err != 1)
 403                         substate = XenbusStateUnknown;
 404
 405                 switch (substate) {
 406                 case XenbusStateInitialising:
 407                         dev_dbg(&pdev->xdev->dev, "Attaching dev-%d ...\n", i);
 408
 409                         len = snprintf(dev_str, sizeof(dev_str), "dev-%d", i);
 410                         if (unlikely(len >= (sizeof(dev_str) - 1))) {
 411                                 err = -ENOMEM;
 412                                 xenbus_dev_fatal(pdev->xdev, err,
 413                                                  "String overflow while "
 414                                                  "reading configuration");
 415                                 goto out;
 416                         }
 417                         err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename,
 418                                            dev_str, "%x:%x:%x.%x",
 419                                            &domain, &bus, &slot, &func);
 420                         if (err < 0) {
 421                                 xenbus_dev_fatal(pdev->xdev, err,
 422                                                  "Error reading device "
 423                                                  "configuration");
 424                                 goto out;
 425                         }
 426                         if (err != 4) {
 427                                 err = -EINVAL;
 428                                 xenbus_dev_fatal(pdev->xdev, err,
 429                                                  "Error parsing pci device "
 430                                                  "configuration");
 431                                 goto out;
 432                         }
 433
 434                         err = xen_pcibk_export_device(pdev, domain, bus, slot,
 435                                                     func, i);
 436                         if (err)
 437                                 goto out;
 438
 439                         /* Publish pci roots. */
 440                         err = xen_pcibk_publish_pci_roots(pdev,
 441                                                 xen_pcibk_publish_pci_root);
 442                         if (err) {
 443                                 xenbus_dev_fatal(pdev->xdev, err,
 444                                                  "Error while publish PCI root"
 445                                                  "buses for frontend");
 446                                 goto out;
 447                         }
 448
 449                         err = xenbus_printf(XBT_NIL, pdev->xdev->nodename,
 450                                             state_str, "%d",
 451                                             XenbusStateInitialised);
 452                         if (err) {
 453                                 xenbus_dev_fatal(pdev->xdev, err,
 454                                                  "Error switching substate of "
 455                                                  "dev-%d\n", i);
 456                                 goto out;
 457                         }
 458                         break;
 459
 460                 case XenbusStateClosing:
 461                         dev_dbg(&pdev->xdev->dev, "Detaching dev-%d ...\n", i);
 462
 463                         len = snprintf(dev_str, sizeof(dev_str), "vdev-%d", i);
 464                         if (unlikely(len >= (sizeof(dev_str) - 1))) {
 465                                 err = -ENOMEM;
 466                                 xenbus_dev_fatal(pdev->xdev, err,
 467                                                  "String overflow while "
 468                                                  "reading configuration");
 469                                 goto out;
 470                         }
 471                         err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename,
 472                                            dev_str, "%x:%x:%x.%x",
 473                                            &domain, &bus, &slot, &func);
 474                         if (err < 0) {
 475                                 xenbus_dev_fatal(pdev->xdev, err,
 476                                                  "Error reading device "
 477                                                  "configuration");
 478                                 goto out;
 479                         }
 480                         if (err != 4) {
 481                                 err = -EINVAL;
 482                                 xenbus_dev_fatal(pdev->xdev, err,
 483                                                  "Error parsing pci device "
 484                                                  "configuration");
 485                                 goto out;
 486                         }
 487
 488                         err = xen_pcibk_remove_device(pdev, domain, bus, slot,
 489                                                     func);
 490                         if (err)
 491                                 goto out;
 492
 493                         /* TODO: If at some point we implement support for pci
 494                          * root hot-remove on pcifront side, we'll need to
 495                          * remove unnecessary xenstore nodes of pci roots here.
 496                          */
 497
 498                         break;
 499
 500                 default:
 501                         break;
 502                 }
 503         }
 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);
 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 **vec, unsigned int len)
 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         default:
 670                 break;
 671         }
 672 }
 673
 674 static int xen_pcibk_xenbus_probe(struct xenbus_device *dev,
 675                                 const struct xenbus_device_id *id)
 676 {
 677         int err = 0;
 678         struct xen_pcibk_device *pdev = alloc_pdev(dev);
 679
 680         if (pdev == NULL) {
 681                 err = -ENOMEM;
 682                 xenbus_dev_fatal(dev, err,
 683                                  "Error allocating xen_pcibk_device struct");
 684                 goto out;
 685         }
 686
 687         /* wait for xend to configure us */
 688         err = xenbus_switch_state(dev, XenbusStateInitWait);
 689         if (err)
 690                 goto out;
 691
 692         /* watch the backend node for backend configuration information */
 693         err = xenbus_watch_path(dev, dev->nodename, &pdev->be_watch,
 694                                 xen_pcibk_be_watch);
 695         if (err)
 696                 goto out;
 697
 698         pdev->be_watching = 1;
 699
 700         /* We need to force a call to our callback here in case
 701          * xend already configured us!
 702          */
 703         xen_pcibk_be_watch(&pdev->be_watch, NULL, 0);
 704
 705 out:
 706         return err;
 707 }
 708
 709 static int xen_pcibk_xenbus_remove(struct xenbus_device *dev)
 710 {
 711         struct xen_pcibk_device *pdev = dev_get_drvdata(&dev->dev);
 712
 713         if (pdev != NULL)
 714                 free_pdev(pdev);
 715
 716         return 0;
 717 }
 718
 719 static const struct xenbus_device_id xen_pcibk_ids[] = {
 720         {"pci"},
 721         {""},
 722 };
 723
 724 static struct xenbus_driver xen_pcibk_driver = {
 725         .name                   = DRV_NAME,
 726         .ids                    = xen_pcibk_ids,
 727         .probe                  = xen_pcibk_xenbus_probe,
 728         .remove                 = xen_pcibk_xenbus_remove,
 729         .otherend_changed       = xen_pcibk_frontend_changed,
 730 };
 731
 732 const struct xen_pcibk_backend *__read_mostly xen_pcibk_backend;
 733
 734 int __init xen_pcibk_xenbus_register(void)
 735 {
 736         xen_pcibk_wq = create_workqueue("xen_pciback_workqueue");
 737         if (!xen_pcibk_wq) {
 738                 pr_err("%s: create xen_pciback_workqueue failed\n", __func__);
 739                 return -EFAULT;
 740         }
 741         xen_pcibk_backend = &xen_pcibk_vpci_backend;
 742         if (passthrough)
 743                 xen_pcibk_backend = &xen_pcibk_passthrough_backend;
 744         pr_info("backend is %s\n", xen_pcibk_backend->name);
 745         return xenbus_register_backend(&xen_pcibk_driver);
 746 }
 747
 748 void __exit xen_pcibk_xenbus_unregister(void)
 749 {
 750         destroy_workqueue(xen_pcibk_wq);
 751         xenbus_unregister_driver(&xen_pcibk_driver);
 752 }