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 <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 hardware 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                                  enum xenbus_state state)
 364 {
 365         int err = 0;
 366         int num_devs;
 367         int domain, bus, slot, func;
 368         unsigned int substate;
 369         int i, len;
 370         char state_str[64];
 371         char dev_str[64];
 372
 373
 374         dev_dbg(&pdev->xdev->dev, "Reconfiguring device ...\n");
 375
 376         mutex_lock(&pdev->dev_lock);
 377         if (xenbus_read_driver_state(pdev->xdev->nodename) != state)
 378                 goto out;
 379
 380         err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename, "num_devs", "%d",
 381                            &num_devs);
 382         if (err != 1) {
 383                 if (err >= 0)
 384                         err = -EINVAL;
 385                 xenbus_dev_fatal(pdev->xdev, err,
 386                                  "Error reading number of devices");
 387                 goto out;
 388         }
 389
 390         for (i = 0; i < num_devs; i++) {
 391                 len = snprintf(state_str, sizeof(state_str), "state-%d", i);
 392                 if (unlikely(len >= (sizeof(state_str) - 1))) {
 393                         err = -ENOMEM;
 394                         xenbus_dev_fatal(pdev->xdev, err,
 395                                          "String overflow while reading "
 396                                          "configuration");
 397                         goto out;
 398                 }
 399                 substate = xenbus_read_unsigned(pdev->xdev->nodename, state_str,
 400                                                 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                 fallthrough;    /* 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 *path, const char *token)
 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, NULL);
 714
 715 out:
 716         return err;
 717 }
 718
 719 static void 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
 727 static const struct xenbus_device_id xen_pcibk_ids[] = {
 728         {"pci"},
 729         {""},
 730 };
 731
 732 static struct xenbus_driver xen_pcibk_driver = {
 733         .name                   = DRV_NAME,
 734         .ids                    = xen_pcibk_ids,
 735         .probe                  = xen_pcibk_xenbus_probe,
 736         .remove                 = xen_pcibk_xenbus_remove,
 737         .otherend_changed       = xen_pcibk_frontend_changed,
 738 };
 739
 740 const struct xen_pcibk_backend *__read_mostly xen_pcibk_backend;
 741
 742 int __init xen_pcibk_xenbus_register(void)
 743 {
 744         if (!xen_pcibk_pv_support())
 745                 return 0;
 746
 747         xen_pcibk_backend = &xen_pcibk_vpci_backend;
 748         if (passthrough)
 749                 xen_pcibk_backend = &xen_pcibk_passthrough_backend;
 750         pr_info("backend is %s\n", xen_pcibk_backend->name);
 751         return xenbus_register_backend(&xen_pcibk_driver);
 752 }
 753
 754 void __exit xen_pcibk_xenbus_unregister(void)
 755 {
 756         if (xen_pcibk_pv_support())
 757                 xenbus_unregister_driver(&xen_pcibk_driver);
 758 }