drivers/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 #include <linux/module.h>
   7 #include <linux/init.h>
   8 #include <linux/list.h>
   9 #include <linux/vmalloc.h>
  10 #include <xen/xenbus.h>
  11 #include <xen/evtchn.h>
  12 #include "pciback.h"
  13
  14 #define INVALID_EVTCHN_IRQ  (-1)
  15
  16 static struct pciback_device *alloc_pdev(struct xenbus_device *xdev)
  17 {
  18         struct pciback_device *pdev;
  19
  20         pdev = kzalloc(sizeof(struct pciback_device), GFP_KERNEL);
  21         if (pdev == NULL)
  22                 goto out;
  23         dev_dbg(&xdev->dev, "allocated pdev @ 0x%p\n", pdev);
  24
  25         pdev->xdev = xdev;
  26         xdev->dev.driver_data = pdev;
  27
  28         spin_lock_init(&pdev->dev_lock);
  29
  30         pdev->sh_area = NULL;
  31         pdev->sh_info = NULL;
  32         pdev->evtchn_irq = INVALID_EVTCHN_IRQ;
  33         pdev->be_watching = 0;
  34
  35         INIT_WORK(&pdev->op_work, pciback_do_op, pdev);
  36
  37         if (pciback_init_devices(pdev)) {
  38                 kfree(pdev);
  39                 pdev = NULL;
  40         }
  41       out:
  42         return pdev;
  43 }
  44
  45 static void free_pdev(struct pciback_device *pdev)
  46 {
  47         if (pdev->be_watching)
  48                 unregister_xenbus_watch(&pdev->be_watch);
  49
  50         /* Ensure the guest can't trigger our handler before removing devices */
  51         if (pdev->evtchn_irq != INVALID_EVTCHN_IRQ)
  52                 unbind_from_irqhandler(pdev->evtchn_irq, pdev);
  53
  54         /* If the driver domain started an op, make sure we complete it or
  55          * delete it before releasing the shared memory */
  56         cancel_delayed_work(&pdev->op_work);
  57         flush_scheduled_work();
  58
  59         if (pdev->sh_info)
  60                 xenbus_unmap_ring_vfree(pdev->xdev, pdev->sh_area);
  61
  62         pciback_release_devices(pdev);
  63
  64         pdev->xdev->dev.driver_data = NULL;
  65         pdev->xdev = NULL;
  66
  67         kfree(pdev);
  68 }
  69
  70 static int pciback_do_attach(struct pciback_device *pdev, int gnt_ref,
  71                              int remote_evtchn)
  72 {
  73         int err = 0;
  74         int evtchn;
  75         struct vm_struct *area;
  76
  77         dev_dbg(&pdev->xdev->dev,
  78                 "Attaching to frontend resources - gnt_ref=%d evtchn=%d\n",
  79                 gnt_ref, remote_evtchn);
  80
  81         area = xenbus_map_ring_valloc(pdev->xdev, gnt_ref);
  82         if (IS_ERR(area)) {
  83                 err = PTR_ERR(area);
  84                 goto out;
  85         }
  86         pdev->sh_area = area;
  87         pdev->sh_info = area->addr;
  88
  89         err = xenbus_bind_evtchn(pdev->xdev, remote_evtchn, &evtchn);
  90         if (err)
  91                 goto out;
  92
  93         err = bind_evtchn_to_irqhandler(evtchn, pciback_handle_event,
  94                                         SA_SAMPLE_RANDOM, "pciback", pdev);
  95         if (err < 0) {
  96                 xenbus_dev_fatal(pdev->xdev, err,
  97                                  "Error binding event channel to IRQ");
  98                 goto out;
  99         }
 100         pdev->evtchn_irq = err;
 101         err = 0;
 102
 103         dev_dbg(&pdev->xdev->dev, "Attached!\n");
 104       out:
 105         return err;
 106 }
 107
 108 static int pciback_attach(struct pciback_device *pdev)
 109 {
 110         int err = 0;
 111         int gnt_ref, remote_evtchn;
 112         char *magic = NULL;
 113
 114         spin_lock(&pdev->dev_lock);
 115
 116         /* Make sure we only do this setup once */
 117         if (xenbus_read_driver_state(pdev->xdev->nodename) !=
 118             XenbusStateInitialised)
 119                 goto out;
 120
 121         /* Wait for frontend to state that it has published the configuration */
 122         if (xenbus_read_driver_state(pdev->xdev->otherend) !=
 123             XenbusStateInitialised)
 124                 goto out;
 125
 126         dev_dbg(&pdev->xdev->dev, "Reading frontend config\n");
 127
 128         err = xenbus_gather(XBT_NIL, pdev->xdev->otherend,
 129                             "pci-op-ref", "%u", &gnt_ref,
 130                             "event-channel", "%u", &remote_evtchn,
 131                             "magic", NULL, &magic, NULL);
 132         if (err) {
 133                 /* If configuration didn't get read correctly, wait longer */
 134                 xenbus_dev_fatal(pdev->xdev, err,
 135                                  "Error reading configuration from frontend");
 136                 goto out;
 137         }
 138
 139         if (magic == NULL || strcmp(magic, XEN_PCI_MAGIC) != 0) {
 140                 xenbus_dev_fatal(pdev->xdev, -EFAULT,
 141                                  "version mismatch (%s/%s) with pcifront - "
 142                                  "halting pciback",
 143                                  magic, XEN_PCI_MAGIC);
 144                 goto out;
 145         }
 146
 147         err = pciback_do_attach(pdev, gnt_ref, remote_evtchn);
 148         if (err)
 149                 goto out;
 150
 151         dev_dbg(&pdev->xdev->dev, "Connecting...\n");
 152
 153         err = xenbus_switch_state(pdev->xdev, XenbusStateConnected);
 154         if (err)
 155                 xenbus_dev_fatal(pdev->xdev, err,
 156                                  "Error switching to connected state!");
 157
 158         dev_dbg(&pdev->xdev->dev, "Connected? %d\n", err);
 159       out:
 160         spin_unlock(&pdev->dev_lock);
 161
 162         if (magic)
 163                 kfree(magic);
 164
 165         return err;
 166 }
 167
 168 static void pciback_frontend_changed(struct xenbus_device *xdev,
 169                                      enum xenbus_state fe_state)
 170 {
 171         struct pciback_device *pdev = xdev->dev.driver_data;
 172
 173         dev_dbg(&xdev->dev, "fe state changed %d\n", fe_state);
 174
 175         switch (fe_state) {
 176         case XenbusStateInitialised:
 177                 pciback_attach(pdev);
 178                 break;
 179
 180         case XenbusStateClosing:
 181                 xenbus_switch_state(xdev, XenbusStateClosing);
 182                 break;
 183
 184         case XenbusStateUnknown:
 185         case XenbusStateClosed:
 186                 dev_dbg(&xdev->dev, "frontend is gone! unregister device\n");
 187                 device_unregister(&xdev->dev);
 188                 break;
 189
 190         default:
 191                 break;
 192         }
 193 }
 194
 195 static int pciback_publish_pci_root(struct pciback_device *pdev,
 196                                     unsigned int domain, unsigned int bus)
 197 {
 198         unsigned int d, b;
 199         int i, root_num, len, err;
 200         char str[64];
 201
 202         dev_dbg(&pdev->xdev->dev, "Publishing pci roots\n");
 203
 204         err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename,
 205                            "root_num", "%d", &root_num);
 206         if (err == 0 || err == -ENOENT)
 207                 root_num = 0;
 208         else if (err < 0)
 209                 goto out;
 210
 211         /* Verify that we haven't already published this pci root */
 212         for (i = 0; i < root_num; i++) {
 213                 len = snprintf(str, sizeof(str), "root-%d", i);
 214                 if (unlikely(len >= (sizeof(str) - 1))) {
 215                         err = -ENOMEM;
 216                         goto out;
 217                 }
 218
 219                 err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename,
 220                                    str, "%x:%x", &d, &b);
 221                 if (err < 0)
 222                         goto out;
 223                 if (err != 2) {
 224                         err = -EINVAL;
 225                         goto out;
 226                 }
 227
 228                 if (d == domain && b == bus) {
 229                         err = 0;
 230                         goto out;
 231                 }
 232         }
 233
 234         len = snprintf(str, sizeof(str), "root-%d", root_num);
 235         if (unlikely(len >= (sizeof(str) - 1))) {
 236                 err = -ENOMEM;
 237                 goto out;
 238         }
 239
 240         dev_dbg(&pdev->xdev->dev, "writing root %d at %04x:%02x\n",
 241                 root_num, domain, bus);
 242
 243         err = xenbus_printf(XBT_NIL, pdev->xdev->nodename, str,
 244                             "%04x:%02x", domain, bus);
 245         if (err)
 246                 goto out;
 247
 248         err = xenbus_printf(XBT_NIL, pdev->xdev->nodename,
 249                             "root_num", "%d", (root_num + 1));
 250
 251       out:
 252         return err;
 253 }
 254
 255 static int pciback_export_device(struct pciback_device *pdev,
 256                                  int domain, int bus, int slot, int func)
 257 {
 258         struct pci_dev *dev;
 259         int err = 0;
 260
 261         dev_dbg(&pdev->xdev->dev, "exporting dom %x bus %x slot %x func %x\n",
 262                 domain, bus, slot, func);
 263
 264         dev = pcistub_get_pci_dev_by_slot(pdev, domain, bus, slot, func);
 265         if (!dev) {
 266                 err = -EINVAL;
 267                 xenbus_dev_fatal(pdev->xdev, err,
 268                                  "Couldn't locate PCI device "
 269                                  "(%04x:%02x:%02x.%01x)! "
 270                                  "perhaps already in-use?",
 271                                  domain, bus, slot, func);
 272                 goto out;
 273         }
 274
 275         err = pciback_add_pci_dev(pdev, dev);
 276         if (err)
 277                 goto out;
 278
 279         /* TODO: It'd be nice to export a bridge and have all of its children
 280          * get exported with it. This may be best done in xend (which will
 281          * have to calculate resource usage anyway) but we probably want to
 282          * put something in here to ensure that if a bridge gets given to a
 283          * driver domain, that all devices under that bridge are not given
 284          * to other driver domains (as he who controls the bridge can disable
 285          * it and stop the other devices from working).
 286          */
 287       out:
 288         return err;
 289 }
 290
 291 static int pciback_setup_backend(struct pciback_device *pdev)
 292 {
 293         /* Get configuration from xend (if available now) */
 294         int domain, bus, slot, func;
 295         int err = 0;
 296         int i, num_devs;
 297         char dev_str[64];
 298
 299         spin_lock(&pdev->dev_lock);
 300
 301         /* It's possible we could get the call to setup twice, so make sure
 302          * we're not already connected.
 303          */
 304         if (xenbus_read_driver_state(pdev->xdev->nodename) !=
 305             XenbusStateInitWait)
 306                 goto out;
 307
 308         dev_dbg(&pdev->xdev->dev, "getting be setup\n");
 309
 310         err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename, "num_devs", "%d",
 311                            &num_devs);
 312         if (err != 1) {
 313                 if (err >= 0)
 314                         err = -EINVAL;
 315                 xenbus_dev_fatal(pdev->xdev, err,
 316                                  "Error reading number of devices");
 317                 goto out;
 318         }
 319
 320         for (i = 0; i < num_devs; i++) {
 321                 int l = snprintf(dev_str, sizeof(dev_str), "dev-%d", i);
 322                 if (unlikely(l >= (sizeof(dev_str) - 1))) {
 323                         err = -ENOMEM;
 324                         xenbus_dev_fatal(pdev->xdev, err,
 325                                          "String overflow while reading "
 326                                          "configuration");
 327                         goto out;
 328                 }
 329
 330                 err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename, dev_str,
 331                                    "%x:%x:%x.%x", &domain, &bus, &slot, &func);
 332                 if (err < 0) {
 333                         xenbus_dev_fatal(pdev->xdev, err,
 334                                          "Error reading device configuration");
 335                         goto out;
 336                 }
 337                 if (err != 4) {
 338                         err = -EINVAL;
 339                         xenbus_dev_fatal(pdev->xdev, err,
 340                                          "Error parsing pci device "
 341                                          "configuration");
 342                         goto out;
 343                 }
 344
 345                 err = pciback_export_device(pdev, domain, bus, slot, func);
 346                 if (err)
 347                         goto out;
 348         }
 349
 350         err = pciback_publish_pci_roots(pdev, pciback_publish_pci_root);
 351         if (err) {
 352                 xenbus_dev_fatal(pdev->xdev, err,
 353                                  "Error while publish PCI root buses "
 354                                  "for frontend");
 355                 goto out;
 356         }
 357
 358         err = xenbus_switch_state(pdev->xdev, XenbusStateInitialised);
 359         if (err)
 360                 xenbus_dev_fatal(pdev->xdev, err,
 361                                  "Error switching to initialised state!");
 362
 363       out:
 364         spin_unlock(&pdev->dev_lock);
 365
 366         if (!err)
 367                 /* see if pcifront is already configured (if not, we'll wait) */
 368                 pciback_attach(pdev);
 369
 370         return err;
 371 }
 372
 373 static void pciback_be_watch(struct xenbus_watch *watch,
 374                              const char **vec, unsigned int len)
 375 {
 376         struct pciback_device *pdev =
 377             container_of(watch, struct pciback_device, be_watch);
 378
 379         switch (xenbus_read_driver_state(pdev->xdev->nodename)) {
 380         case XenbusStateInitWait:
 381                 pciback_setup_backend(pdev);
 382                 break;
 383
 384         default:
 385                 break;
 386         }
 387 }
 388
 389 static int pciback_xenbus_probe(struct xenbus_device *dev,
 390                                 const struct xenbus_device_id *id)
 391 {
 392         int err = 0;
 393         struct pciback_device *pdev = alloc_pdev(dev);
 394
 395         if (pdev == NULL) {
 396                 err = -ENOMEM;
 397                 xenbus_dev_fatal(dev, err,
 398                                  "Error allocating pciback_device struct");
 399                 goto out;
 400         }
 401
 402         /* wait for xend to configure us */
 403         err = xenbus_switch_state(dev, XenbusStateInitWait);
 404         if (err)
 405                 goto out;
 406
 407         /* watch the backend node for backend configuration information */
 408         err = xenbus_watch_path(dev, dev->nodename, &pdev->be_watch,
 409                                 pciback_be_watch);
 410         if (err)
 411                 goto out;
 412         pdev->be_watching = 1;
 413
 414         /* We need to force a call to our callback here in case
 415          * xend already configured us!
 416          */
 417         pciback_be_watch(&pdev->be_watch, NULL, 0);
 418
 419       out:
 420         return err;
 421 }
 422
 423 static int pciback_xenbus_remove(struct xenbus_device *dev)
 424 {
 425         struct pciback_device *pdev = dev->dev.driver_data;
 426
 427         if (pdev != NULL)
 428                 free_pdev(pdev);
 429
 430         return 0;
 431 }
 432
 433 static struct xenbus_device_id xenpci_ids[] = {
 434         {"pci"},
 435         {{0}},
 436 };
 437
 438 static struct xenbus_driver xenbus_pciback_driver = {
 439         .name                   = "pciback",
 440         .owner                  = THIS_MODULE,
 441         .ids                    = xenpci_ids,
 442         .probe                  = pciback_xenbus_probe,
 443         .remove                 = pciback_xenbus_remove,
 444         .otherend_changed       = pciback_frontend_changed,
 445 };
 446
 447 int __init pciback_xenbus_register(void)
 448 {
 449         if (!is_running_on_xen())
 450                 return -ENODEV;
 451
 452         return xenbus_register_backend(&xenbus_pciback_driver);
 453 }
 454
 455 void __exit pciback_xenbus_unregister(void)
 456 {
 457         xenbus_unregister_driver(&xenbus_pciback_driver);
 458 }