Pileus Git - ~andy/linux/blob - drivers/xen/xenbus/xenbus_probe_frontend.c

   1 #define DPRINTK(fmt, args...)                           \
   2         pr_debug("xenbus_probe (%s:%d) " fmt ".\n",     \
   3                  __func__, __LINE__, ##args)
   4
   5 #include <linux/kernel.h>
   6 #include <linux/err.h>
   7 #include <linux/string.h>
   8 #include <linux/ctype.h>
   9 #include <linux/fcntl.h>
  10 #include <linux/mm.h>
  11 #include <linux/proc_fs.h>
  12 #include <linux/notifier.h>
  13 #include <linux/kthread.h>
  14 #include <linux/mutex.h>
  15 #include <linux/io.h>
  16 #include <linux/module.h>
  17
  18 #include <asm/page.h>
  19 #include <asm/pgtable.h>
  20 #include <asm/xen/hypervisor.h>
  21 #include <xen/xenbus.h>
  22 #include <xen/events.h>
  23 #include <xen/page.h>
  24 #include <xen/xen.h>
  25
  26 #include <xen/platform_pci.h>
  27
  28 #include "xenbus_comms.h"
  29 #include "xenbus_probe.h"
  30
  31
  32 /* device/<type>/<id> => <type>-<id> */
  33 static int frontend_bus_id(char bus_id[XEN_BUS_ID_SIZE], const char *nodename)
  34 {
  35         nodename = strchr(nodename, '/');
  36         if (!nodename || strlen(nodename + 1) >= XEN_BUS_ID_SIZE) {
  37                 printk(KERN_WARNING "XENBUS: bad frontend %s\n", nodename);
  38                 return -EINVAL;
  39         }
  40
  41         strlcpy(bus_id, nodename + 1, XEN_BUS_ID_SIZE);
  42         if (!strchr(bus_id, '/')) {
  43                 printk(KERN_WARNING "XENBUS: bus_id %s no slash\n", bus_id);
  44                 return -EINVAL;
  45         }
  46         *strchr(bus_id, '/') = '-';
  47         return 0;
  48 }
  49
  50 /* device/<typename>/<name> */
  51 static int xenbus_probe_frontend(struct xen_bus_type *bus, const char *type,
  52                                  const char *name)
  53 {
  54         char *nodename;
  55         int err;
  56
  57         /* ignore console/0 */
  58         if (!strncmp(type, "console", 7) && !strncmp(name, "0", 1)) {
  59                 DPRINTK("Ignoring buggy device entry console/0");
  60                 return 0;
  61         }
  62
  63         nodename = kasprintf(GFP_KERNEL, "%s/%s/%s", bus->root, type, name);
  64         if (!nodename)
  65                 return -ENOMEM;
  66
  67         DPRINTK("%s", nodename);
  68
  69         err = xenbus_probe_node(bus, type, nodename);
  70         kfree(nodename);
  71         return err;
  72 }
  73
  74 static int xenbus_uevent_frontend(struct device *_dev,
  75                                   struct kobj_uevent_env *env)
  76 {
  77         struct xenbus_device *dev = to_xenbus_device(_dev);
  78
  79         if (add_uevent_var(env, "MODALIAS=xen:%s", dev->devicetype))
  80                 return -ENOMEM;
  81
  82         return 0;
  83 }
  84
  85
  86 static void backend_changed(struct xenbus_watch *watch,
  87                             const char **vec, unsigned int len)
  88 {
  89         xenbus_otherend_changed(watch, vec, len, 1);
  90 }
  91
  92 static const struct dev_pm_ops xenbus_pm_ops = {
  93         .suspend        = xenbus_dev_suspend,
  94         .resume         = xenbus_dev_resume,
  95         .freeze         = xenbus_dev_suspend,
  96         .thaw           = xenbus_dev_cancel,
  97         .restore        = xenbus_dev_resume,
  98 };
  99
 100 static struct xen_bus_type xenbus_frontend = {
 101         .root = "device",
 102         .levels = 2,            /* device/type/<id> */
 103         .get_bus_id = frontend_bus_id,
 104         .probe = xenbus_probe_frontend,
 105         .otherend_changed = backend_changed,
 106         .bus = {
 107                 .name           = "xen",
 108                 .match          = xenbus_match,
 109                 .uevent         = xenbus_uevent_frontend,
 110                 .probe          = xenbus_dev_probe,
 111                 .remove         = xenbus_dev_remove,
 112                 .shutdown       = xenbus_dev_shutdown,
 113                 .dev_attrs      = xenbus_dev_attrs,
 114
 115                 .pm             = &xenbus_pm_ops,
 116         },
 117 };
 118
 119 static void frontend_changed(struct xenbus_watch *watch,
 120                              const char **vec, unsigned int len)
 121 {
 122         DPRINTK("");
 123
 124         xenbus_dev_changed(vec[XS_WATCH_PATH], &xenbus_frontend);
 125 }
 126
 127
 128 /* We watch for devices appearing and vanishing. */
 129 static struct xenbus_watch fe_watch = {
 130         .node = "device",
 131         .callback = frontend_changed,
 132 };
 133
 134 static int read_backend_details(struct xenbus_device *xendev)
 135 {
 136         return xenbus_read_otherend_details(xendev, "backend-id", "backend");
 137 }
 138
 139 static int is_device_connecting(struct device *dev, void *data, bool ignore_nonessential)
 140 {
 141         struct xenbus_device *xendev = to_xenbus_device(dev);
 142         struct device_driver *drv = data;
 143         struct xenbus_driver *xendrv;
 144
 145         /*
 146          * A device with no driver will never connect. We care only about
 147          * devices which should currently be in the process of connecting.
 148          */
 149         if (!dev->driver)
 150                 return 0;
 151
 152         /* Is this search limited to a particular driver? */
 153         if (drv && (dev->driver != drv))
 154                 return 0;
 155
 156         if (ignore_nonessential) {
 157                 /* With older QEMU, for PVonHVM guests the guest config files
 158                  * could contain: vfb = [ 'vnc=1, vnclisten=0.0.0.0']
 159                  * which is nonsensical as there is no PV FB (there can be
 160                  * a PVKB) running as HVM guest. */
 161
 162                 if ((strncmp(xendev->nodename, "device/vkbd", 11) == 0))
 163                         return 0;
 164
 165                 if ((strncmp(xendev->nodename, "device/vfb", 10) == 0))
 166                         return 0;
 167         }
 168         xendrv = to_xenbus_driver(dev->driver);
 169         return (xendev->state < XenbusStateConnected ||
 170                 (xendev->state == XenbusStateConnected &&
 171                  xendrv->is_ready && !xendrv->is_ready(xendev)));
 172 }
 173 static int essential_device_connecting(struct device *dev, void *data)
 174 {
 175         return is_device_connecting(dev, data, true /* ignore PV[KBB+FB] */);
 176 }
 177 static int non_essential_device_connecting(struct device *dev, void *data)
 178 {
 179         return is_device_connecting(dev, data, false);
 180 }
 181
 182 static int exists_essential_connecting_device(struct device_driver *drv)
 183 {
 184         return bus_for_each_dev(&xenbus_frontend.bus, NULL, drv,
 185                                 essential_device_connecting);
 186 }
 187 static int exists_non_essential_connecting_device(struct device_driver *drv)
 188 {
 189         return bus_for_each_dev(&xenbus_frontend.bus, NULL, drv,
 190                                 non_essential_device_connecting);
 191 }
 192
 193 static int print_device_status(struct device *dev, void *data)
 194 {
 195         struct xenbus_device *xendev = to_xenbus_device(dev);
 196         struct device_driver *drv = data;
 197
 198         /* Is this operation limited to a particular driver? */
 199         if (drv && (dev->driver != drv))
 200                 return 0;
 201
 202         if (!dev->driver) {
 203                 /* Information only: is this too noisy? */
 204                 printk(KERN_INFO "XENBUS: Device with no driver: %s\n",
 205                        xendev->nodename);
 206         } else if (xendev->state < XenbusStateConnected) {
 207                 enum xenbus_state rstate = XenbusStateUnknown;
 208                 if (xendev->otherend)
 209                         rstate = xenbus_read_driver_state(xendev->otherend);
 210                 printk(KERN_WARNING "XENBUS: Timeout connecting "
 211                        "to device: %s (local state %d, remote state %d)\n",
 212                        xendev->nodename, xendev->state, rstate);
 213         }
 214
 215         return 0;
 216 }
 217
 218 /* We only wait for device setup after most initcalls have run. */
 219 static int ready_to_wait_for_devices;
 220
 221 static bool wait_loop(unsigned long start, unsigned int max_delay,
 222                      unsigned int *seconds_waited)
 223 {
 224         if (time_after(jiffies, start + (*seconds_waited+5)*HZ)) {
 225                 if (!*seconds_waited)
 226                         printk(KERN_WARNING "XENBUS: Waiting for "
 227                                "devices to initialise: ");
 228                 *seconds_waited += 5;
 229                 printk("%us...", max_delay - *seconds_waited);
 230                 if (*seconds_waited == max_delay)
 231                         return true;
 232         }
 233
 234         schedule_timeout_interruptible(HZ/10);
 235
 236         return false;
 237 }
 238 /*
 239  * On a 5-minute timeout, wait for all devices currently configured.  We need
 240  * to do this to guarantee that the filesystems and / or network devices
 241  * needed for boot are available, before we can allow the boot to proceed.
 242  *
 243  * This needs to be on a late_initcall, to happen after the frontend device
 244  * drivers have been initialised, but before the root fs is mounted.
 245  *
 246  * A possible improvement here would be to have the tools add a per-device
 247  * flag to the store entry, indicating whether it is needed at boot time.
 248  * This would allow people who knew what they were doing to accelerate their
 249  * boot slightly, but of course needs tools or manual intervention to set up
 250  * those flags correctly.
 251  */
 252 static void wait_for_devices(struct xenbus_driver *xendrv)
 253 {
 254         unsigned long start = jiffies;
 255         struct device_driver *drv = xendrv ? &xendrv->driver : NULL;
 256         unsigned int seconds_waited = 0;
 257
 258         if (!ready_to_wait_for_devices || !xen_domain())
 259                 return;
 260
 261         while (exists_non_essential_connecting_device(drv))
 262                 if (wait_loop(start, 30, &seconds_waited))
 263                         break;
 264
 265         /* Skips PVKB and PVFB check.*/
 266         while (exists_essential_connecting_device(drv))
 267                 if (wait_loop(start, 270, &seconds_waited))
 268                         break;
 269
 270         if (seconds_waited)
 271                 printk("\n");
 272
 273         bus_for_each_dev(&xenbus_frontend.bus, NULL, drv,
 274                          print_device_status);
 275 }
 276
 277 int xenbus_register_frontend(struct xenbus_driver *drv)
 278 {
 279         int ret;
 280
 281         drv->read_otherend_details = read_backend_details;
 282
 283         ret = xenbus_register_driver_common(drv, &xenbus_frontend);
 284         if (ret)
 285                 return ret;
 286
 287         /* If this driver is loaded as a module wait for devices to attach. */
 288         wait_for_devices(drv);
 289
 290         return 0;
 291 }
 292 EXPORT_SYMBOL_GPL(xenbus_register_frontend);
 293
 294 static DECLARE_WAIT_QUEUE_HEAD(backend_state_wq);
 295 static int backend_state;
 296
 297 static void xenbus_reset_backend_state_changed(struct xenbus_watch *w,
 298                                         const char **v, unsigned int l)
 299 {
 300         xenbus_scanf(XBT_NIL, v[XS_WATCH_PATH], "", "%i", &backend_state);
 301         printk(KERN_DEBUG "XENBUS: backend %s %s\n",
 302                         v[XS_WATCH_PATH], xenbus_strstate(backend_state));
 303         wake_up(&backend_state_wq);
 304 }
 305
 306 static void xenbus_reset_wait_for_backend(char *be, int expected)
 307 {
 308         long timeout;
 309         timeout = wait_event_interruptible_timeout(backend_state_wq,
 310                         backend_state == expected, 5 * HZ);
 311         if (timeout <= 0)
 312                 printk(KERN_INFO "XENBUS: backend %s timed out.\n", be);
 313 }
 314
 315 /*
 316  * Reset frontend if it is in Connected or Closed state.
 317  * Wait for backend to catch up.
 318  * State Connected happens during kdump, Closed after kexec.
 319  */
 320 static void xenbus_reset_frontend(char *fe, char *be, int be_state)
 321 {
 322         struct xenbus_watch be_watch;
 323
 324         printk(KERN_DEBUG "XENBUS: backend %s %s\n",
 325                         be, xenbus_strstate(be_state));
 326
 327         memset(&be_watch, 0, sizeof(be_watch));
 328         be_watch.node = kasprintf(GFP_NOIO | __GFP_HIGH, "%s/state", be);
 329         if (!be_watch.node)
 330                 return;
 331
 332         be_watch.callback = xenbus_reset_backend_state_changed;
 333         backend_state = XenbusStateUnknown;
 334
 335         printk(KERN_INFO "XENBUS: triggering reconnect on %s\n", be);
 336         register_xenbus_watch(&be_watch);
 337
 338         /* fall through to forward backend to state XenbusStateInitialising */
 339         switch (be_state) {
 340         case XenbusStateConnected:
 341                 xenbus_printf(XBT_NIL, fe, "state", "%d", XenbusStateClosing);
 342                 xenbus_reset_wait_for_backend(be, XenbusStateClosing);
 343
 344         case XenbusStateClosing:
 345                 xenbus_printf(XBT_NIL, fe, "state", "%d", XenbusStateClosed);
 346                 xenbus_reset_wait_for_backend(be, XenbusStateClosed);
 347
 348         case XenbusStateClosed:
 349                 xenbus_printf(XBT_NIL, fe, "state", "%d", XenbusStateInitialising);
 350                 xenbus_reset_wait_for_backend(be, XenbusStateInitWait);
 351         }
 352
 353         unregister_xenbus_watch(&be_watch);
 354         printk(KERN_INFO "XENBUS: reconnect done on %s\n", be);
 355         kfree(be_watch.node);
 356 }
 357
 358 static void xenbus_check_frontend(char *class, char *dev)
 359 {
 360         int be_state, fe_state, err;
 361         char *backend, *frontend;
 362
 363         frontend = kasprintf(GFP_NOIO | __GFP_HIGH, "device/%s/%s", class, dev);
 364         if (!frontend)
 365                 return;
 366
 367         err = xenbus_scanf(XBT_NIL, frontend, "state", "%i", &fe_state);
 368         if (err != 1)
 369                 goto out;
 370
 371         switch (fe_state) {
 372         case XenbusStateConnected:
 373         case XenbusStateClosed:
 374                 printk(KERN_DEBUG "XENBUS: frontend %s %s\n",
 375                                 frontend, xenbus_strstate(fe_state));
 376                 backend = xenbus_read(XBT_NIL, frontend, "backend", NULL);
 377                 if (!backend || IS_ERR(backend))
 378                         goto out;
 379                 err = xenbus_scanf(XBT_NIL, backend, "state", "%i", &be_state);
 380                 if (err == 1)
 381                         xenbus_reset_frontend(frontend, backend, be_state);
 382                 kfree(backend);
 383                 break;
 384         default:
 385                 break;
 386         }
 387 out:
 388         kfree(frontend);
 389 }
 390
 391 static void xenbus_reset_state(void)
 392 {
 393         char **devclass, **dev;
 394         int devclass_n, dev_n;
 395         int i, j;
 396
 397         devclass = xenbus_directory(XBT_NIL, "device", "", &devclass_n);
 398         if (IS_ERR(devclass))
 399                 return;
 400
 401         for (i = 0; i < devclass_n; i++) {
 402                 dev = xenbus_directory(XBT_NIL, "device", devclass[i], &dev_n);
 403                 if (IS_ERR(dev))
 404                         continue;
 405                 for (j = 0; j < dev_n; j++)
 406                         xenbus_check_frontend(devclass[i], dev[j]);
 407                 kfree(dev);
 408         }
 409         kfree(devclass);
 410 }
 411
 412 static int frontend_probe_and_watch(struct notifier_block *notifier,
 413                                    unsigned long event,
 414                                    void *data)
 415 {
 416         /* reset devices in Connected or Closed state */
 417         if (xen_hvm_domain())
 418                 xenbus_reset_state();
 419         /* Enumerate devices in xenstore and watch for changes. */
 420         xenbus_probe_devices(&xenbus_frontend);
 421         register_xenbus_watch(&fe_watch);
 422
 423         return NOTIFY_DONE;
 424 }
 425
 426
 427 static int __init xenbus_probe_frontend_init(void)
 428 {
 429         static struct notifier_block xenstore_notifier = {
 430                 .notifier_call = frontend_probe_and_watch
 431         };
 432         int err;
 433
 434         DPRINTK("");
 435
 436         /* Register ourselves with the kernel bus subsystem */
 437         err = bus_register(&xenbus_frontend.bus);
 438         if (err)
 439                 return err;
 440
 441         register_xenstore_notifier(&xenstore_notifier);
 442
 443         return 0;
 444 }
 445 subsys_initcall(xenbus_probe_frontend_init);
 446
 447 #ifndef MODULE
 448 static int __init boot_wait_for_devices(void)
 449 {
 450         if (xen_hvm_domain() && !xen_platform_pci_unplug)
 451                 return -ENODEV;
 452
 453         ready_to_wait_for_devices = 1;
 454         wait_for_devices(NULL);
 455         return 0;
 456 }
 457
 458 late_initcall(boot_wait_for_devices);
 459 #endif
 460
 461 MODULE_LICENSE("GPL");