517 lines · c
1// SPDX-License-Identifier: GPL-2.0-only2#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt3 4#define DPRINTK(fmt, ...) \5 pr_debug("(%s:%d) " fmt "\n", \6 __func__, __LINE__, ##__VA_ARGS__)7 8#include <linux/kernel.h>9#include <linux/err.h>10#include <linux/string.h>11#include <linux/ctype.h>12#include <linux/fcntl.h>13#include <linux/mm.h>14#include <linux/proc_fs.h>15#include <linux/notifier.h>16#include <linux/kthread.h>17#include <linux/mutex.h>18#include <linux/io.h>19#include <linux/module.h>20 21#include <asm/page.h>22#include <asm/xen/hypervisor.h>23#include <xen/xenbus.h>24#include <xen/events.h>25#include <xen/page.h>26#include <xen/xen.h>27 28#include <xen/platform_pci.h>29 30#include "xenbus.h"31 32 33 34/* device/<type>/<id> => <type>-<id> */35static int frontend_bus_id(char bus_id[XEN_BUS_ID_SIZE], const char *nodename)36{37 nodename = strchr(nodename, '/');38 if (!nodename || strlen(nodename + 1) >= XEN_BUS_ID_SIZE) {39 pr_warn("bad frontend %s\n", nodename);40 return -EINVAL;41 }42 43 strscpy(bus_id, nodename + 1, XEN_BUS_ID_SIZE);44 if (!strchr(bus_id, '/')) {45 pr_warn("bus_id %s no slash\n", bus_id);46 return -EINVAL;47 }48 *strchr(bus_id, '/') = '-';49 return 0;50}51 52/* device/<typename>/<name> */53static int xenbus_probe_frontend(struct xen_bus_type *bus, const char *type,54 const char *name)55{56 char *nodename;57 int err;58 59 /* ignore console/0 */60 if (!strncmp(type, "console", 7) && !strncmp(name, "0", 1)) {61 DPRINTK("Ignoring buggy device entry console/0");62 return 0;63 }64 65 nodename = kasprintf(GFP_KERNEL, "%s/%s/%s", bus->root, type, name);66 if (!nodename)67 return -ENOMEM;68 69 DPRINTK("%s", nodename);70 71 err = xenbus_probe_node(bus, type, nodename);72 kfree(nodename);73 return err;74}75 76static int xenbus_uevent_frontend(const struct device *_dev,77 struct kobj_uevent_env *env)78{79 const struct xenbus_device *dev = to_xenbus_device(_dev);80 81 if (add_uevent_var(env, "MODALIAS=xen:%s", dev->devicetype))82 return -ENOMEM;83 84 return 0;85}86 87 88static void backend_changed(struct xenbus_watch *watch,89 const char *path, const char *token)90{91 xenbus_otherend_changed(watch, path, token, 1);92}93 94static void xenbus_frontend_delayed_resume(struct work_struct *w)95{96 struct xenbus_device *xdev = container_of(w, struct xenbus_device, work);97 98 xenbus_dev_resume(&xdev->dev);99}100 101static int xenbus_frontend_dev_resume(struct device *dev)102{103 /*104 * If xenstored is running in this domain, we cannot access the backend105 * state at the moment, so we need to defer xenbus_dev_resume106 */107 if (xen_store_domain_type == XS_LOCAL) {108 struct xenbus_device *xdev = to_xenbus_device(dev);109 110 schedule_work(&xdev->work);111 112 return 0;113 }114 115 return xenbus_dev_resume(dev);116}117 118static int xenbus_frontend_dev_probe(struct device *dev)119{120 if (xen_store_domain_type == XS_LOCAL) {121 struct xenbus_device *xdev = to_xenbus_device(dev);122 INIT_WORK(&xdev->work, xenbus_frontend_delayed_resume);123 }124 125 return xenbus_dev_probe(dev);126}127 128static void xenbus_frontend_dev_shutdown(struct device *_dev)129{130 struct xenbus_device *dev = to_xenbus_device(_dev);131 unsigned long timeout = 5*HZ;132 133 DPRINTK("%s", dev->nodename);134 135 get_device(&dev->dev);136 if (dev->state != XenbusStateConnected) {137 pr_info("%s: %s: %s != Connected, skipping\n",138 __func__, dev->nodename, xenbus_strstate(dev->state));139 goto out;140 }141 xenbus_switch_state(dev, XenbusStateClosing);142 timeout = wait_for_completion_timeout(&dev->down, timeout);143 if (!timeout)144 pr_info("%s: %s timeout closing device\n",145 __func__, dev->nodename);146 out:147 put_device(&dev->dev);148}149 150static const struct dev_pm_ops xenbus_pm_ops = {151 .suspend = xenbus_dev_suspend,152 .resume = xenbus_frontend_dev_resume,153 .freeze = xenbus_dev_suspend,154 .thaw = xenbus_dev_cancel,155 .restore = xenbus_dev_resume,156};157 158static struct xen_bus_type xenbus_frontend = {159 .root = "device",160 .levels = 2, /* device/type/<id> */161 .get_bus_id = frontend_bus_id,162 .probe = xenbus_probe_frontend,163 .otherend_changed = backend_changed,164 .bus = {165 .name = "xen",166 .match = xenbus_match,167 .uevent = xenbus_uevent_frontend,168 .probe = xenbus_frontend_dev_probe,169 .remove = xenbus_dev_remove,170 .shutdown = xenbus_frontend_dev_shutdown,171 .dev_groups = xenbus_dev_groups,172 173 .pm = &xenbus_pm_ops,174 },175};176 177static void frontend_changed(struct xenbus_watch *watch,178 const char *path, const char *token)179{180 DPRINTK("");181 182 xenbus_dev_changed(path, &xenbus_frontend);183}184 185 186/* We watch for devices appearing and vanishing. */187static struct xenbus_watch fe_watch = {188 .node = "device",189 .callback = frontend_changed,190};191 192static int read_backend_details(struct xenbus_device *xendev)193{194 return xenbus_read_otherend_details(xendev, "backend-id", "backend");195}196 197static int is_device_connecting(struct device *dev, void *data, bool ignore_nonessential)198{199 struct xenbus_device *xendev = to_xenbus_device(dev);200 struct device_driver *drv = data;201 struct xenbus_driver *xendrv;202 203 /*204 * A device with no driver will never connect. We care only about205 * devices which should currently be in the process of connecting.206 */207 if (!dev->driver)208 return 0;209 210 /* Is this search limited to a particular driver? */211 if (drv && (dev->driver != drv))212 return 0;213 214 xendrv = to_xenbus_driver(dev->driver);215 216 if (ignore_nonessential && xendrv->not_essential)217 return 0;218 219 return (xendev->state < XenbusStateConnected ||220 (xendev->state == XenbusStateConnected &&221 xendrv->is_ready && !xendrv->is_ready(xendev)));222}223static int essential_device_connecting(struct device *dev, void *data)224{225 return is_device_connecting(dev, data, true /* ignore PV[KBB+FB] */);226}227static int non_essential_device_connecting(struct device *dev, void *data)228{229 return is_device_connecting(dev, data, false);230}231 232static int exists_essential_connecting_device(struct device_driver *drv)233{234 return bus_for_each_dev(&xenbus_frontend.bus, NULL, drv,235 essential_device_connecting);236}237static int exists_non_essential_connecting_device(struct device_driver *drv)238{239 return bus_for_each_dev(&xenbus_frontend.bus, NULL, drv,240 non_essential_device_connecting);241}242 243static int print_device_status(struct device *dev, void *data)244{245 struct xenbus_device *xendev = to_xenbus_device(dev);246 struct device_driver *drv = data;247 248 /* Is this operation limited to a particular driver? */249 if (drv && (dev->driver != drv))250 return 0;251 252 if (!dev->driver) {253 /* Information only: is this too noisy? */254 pr_info("Device with no driver: %s\n", xendev->nodename);255 } else if (xendev->state < XenbusStateConnected) {256 enum xenbus_state rstate = XenbusStateUnknown;257 if (xendev->otherend)258 rstate = xenbus_read_driver_state(xendev->otherend);259 pr_warn("Timeout connecting to device: %s (local state %d, remote state %d)\n",260 xendev->nodename, xendev->state, rstate);261 }262 263 return 0;264}265 266/* We only wait for device setup after most initcalls have run. */267static int ready_to_wait_for_devices;268 269static bool wait_loop(unsigned long start, unsigned int max_delay,270 unsigned int *seconds_waited)271{272 if (time_after(jiffies, start + (*seconds_waited+5)*HZ)) {273 if (!*seconds_waited)274 pr_warn("Waiting for devices to initialise: ");275 *seconds_waited += 5;276 pr_cont("%us...", max_delay - *seconds_waited);277 if (*seconds_waited == max_delay) {278 pr_cont("\n");279 return true;280 }281 }282 283 schedule_timeout_interruptible(HZ/10);284 285 return false;286}287/*288 * On a 5-minute timeout, wait for all devices currently configured. We need289 * to do this to guarantee that the filesystems and / or network devices290 * needed for boot are available, before we can allow the boot to proceed.291 *292 * This needs to be on a late_initcall, to happen after the frontend device293 * drivers have been initialised, but before the root fs is mounted.294 *295 * A possible improvement here would be to have the tools add a per-device296 * flag to the store entry, indicating whether it is needed at boot time.297 * This would allow people who knew what they were doing to accelerate their298 * boot slightly, but of course needs tools or manual intervention to set up299 * those flags correctly.300 */301static void wait_for_devices(struct xenbus_driver *xendrv)302{303 unsigned long start = jiffies;304 struct device_driver *drv = xendrv ? &xendrv->driver : NULL;305 unsigned int seconds_waited = 0;306 307 if (!ready_to_wait_for_devices || !xen_domain())308 return;309 310 while (exists_non_essential_connecting_device(drv))311 if (wait_loop(start, 30, &seconds_waited))312 break;313 314 /* Skips PVKB and PVFB check.*/315 while (exists_essential_connecting_device(drv))316 if (wait_loop(start, 270, &seconds_waited))317 break;318 319 if (seconds_waited)320 printk("\n");321 322 bus_for_each_dev(&xenbus_frontend.bus, NULL, drv,323 print_device_status);324}325 326int __xenbus_register_frontend(struct xenbus_driver *drv, struct module *owner,327 const char *mod_name)328{329 int ret;330 331 drv->read_otherend_details = read_backend_details;332 333 ret = xenbus_register_driver_common(drv, &xenbus_frontend,334 owner, mod_name);335 if (ret)336 return ret;337 338 /* If this driver is loaded as a module wait for devices to attach. */339 wait_for_devices(drv);340 341 return 0;342}343EXPORT_SYMBOL_GPL(__xenbus_register_frontend);344 345static DECLARE_WAIT_QUEUE_HEAD(backend_state_wq);346static int backend_state;347 348static void xenbus_reset_backend_state_changed(struct xenbus_watch *w,349 const char *path, const char *token)350{351 if (xenbus_scanf(XBT_NIL, path, "", "%i",352 &backend_state) != 1)353 backend_state = XenbusStateUnknown;354 printk(KERN_DEBUG "XENBUS: backend %s %s\n",355 path, xenbus_strstate(backend_state));356 wake_up(&backend_state_wq);357}358 359static void xenbus_reset_wait_for_backend(char *be, int expected)360{361 long timeout;362 timeout = wait_event_interruptible_timeout(backend_state_wq,363 backend_state == expected, 5 * HZ);364 if (timeout <= 0)365 pr_info("backend %s timed out\n", be);366}367 368/*369 * Reset frontend if it is in Connected or Closed state.370 * Wait for backend to catch up.371 * State Connected happens during kdump, Closed after kexec.372 */373static void xenbus_reset_frontend(char *fe, char *be, int be_state)374{375 struct xenbus_watch be_watch;376 377 printk(KERN_DEBUG "XENBUS: backend %s %s\n",378 be, xenbus_strstate(be_state));379 380 memset(&be_watch, 0, sizeof(be_watch));381 be_watch.node = kasprintf(GFP_NOIO | __GFP_HIGH, "%s/state", be);382 if (!be_watch.node)383 return;384 385 be_watch.callback = xenbus_reset_backend_state_changed;386 backend_state = XenbusStateUnknown;387 388 pr_info("triggering reconnect on %s\n", be);389 register_xenbus_watch(&be_watch);390 391 /* fall through to forward backend to state XenbusStateInitialising */392 switch (be_state) {393 case XenbusStateConnected:394 xenbus_printf(XBT_NIL, fe, "state", "%d", XenbusStateClosing);395 xenbus_reset_wait_for_backend(be, XenbusStateClosing);396 fallthrough;397 398 case XenbusStateClosing:399 xenbus_printf(XBT_NIL, fe, "state", "%d", XenbusStateClosed);400 xenbus_reset_wait_for_backend(be, XenbusStateClosed);401 fallthrough;402 403 case XenbusStateClosed:404 xenbus_printf(XBT_NIL, fe, "state", "%d", XenbusStateInitialising);405 xenbus_reset_wait_for_backend(be, XenbusStateInitWait);406 }407 408 unregister_xenbus_watch(&be_watch);409 pr_info("reconnect done on %s\n", be);410 kfree(be_watch.node);411}412 413static void xenbus_check_frontend(char *class, char *dev)414{415 int be_state, fe_state, err;416 char *backend, *frontend;417 418 frontend = kasprintf(GFP_NOIO | __GFP_HIGH, "device/%s/%s", class, dev);419 if (!frontend)420 return;421 422 err = xenbus_scanf(XBT_NIL, frontend, "state", "%i", &fe_state);423 if (err != 1)424 goto out;425 426 switch (fe_state) {427 case XenbusStateConnected:428 case XenbusStateClosed:429 printk(KERN_DEBUG "XENBUS: frontend %s %s\n",430 frontend, xenbus_strstate(fe_state));431 backend = xenbus_read(XBT_NIL, frontend, "backend", NULL);432 if (IS_ERR_OR_NULL(backend))433 goto out;434 err = xenbus_scanf(XBT_NIL, backend, "state", "%i", &be_state);435 if (err == 1)436 xenbus_reset_frontend(frontend, backend, be_state);437 kfree(backend);438 break;439 default:440 break;441 }442out:443 kfree(frontend);444}445 446static void xenbus_reset_state(void)447{448 char **devclass, **dev;449 int devclass_n, dev_n;450 int i, j;451 452 devclass = xenbus_directory(XBT_NIL, "device", "", &devclass_n);453 if (IS_ERR(devclass))454 return;455 456 for (i = 0; i < devclass_n; i++) {457 dev = xenbus_directory(XBT_NIL, "device", devclass[i], &dev_n);458 if (IS_ERR(dev))459 continue;460 for (j = 0; j < dev_n; j++)461 xenbus_check_frontend(devclass[i], dev[j]);462 kfree(dev);463 }464 kfree(devclass);465}466 467static int frontend_probe_and_watch(struct notifier_block *notifier,468 unsigned long event,469 void *data)470{471 /* reset devices in Connected or Closed state */472 if (xen_hvm_domain())473 xenbus_reset_state();474 /* Enumerate devices in xenstore and watch for changes. */475 xenbus_probe_devices(&xenbus_frontend);476 register_xenbus_watch(&fe_watch);477 478 return NOTIFY_DONE;479}480 481 482static int __init xenbus_probe_frontend_init(void)483{484 static struct notifier_block xenstore_notifier = {485 .notifier_call = frontend_probe_and_watch486 };487 int err;488 489 DPRINTK("");490 491 /* Register ourselves with the kernel bus subsystem */492 err = bus_register(&xenbus_frontend.bus);493 if (err)494 return err;495 496 register_xenstore_notifier(&xenstore_notifier);497 498 return 0;499}500subsys_initcall(xenbus_probe_frontend_init);501 502#ifndef MODULE503static int __init boot_wait_for_devices(void)504{505 if (!xen_has_pv_devices())506 return -ENODEV;507 508 ready_to_wait_for_devices = 1;509 wait_for_devices(NULL);510 return 0;511}512 513late_initcall(boot_wait_for_devices);514#endif515 516MODULE_LICENSE("GPL");517