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"); 462