// SPDX-License-Identifier: GPL-2.0-only #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #define DPRINTK(fmt, ...) \ pr_debug("(%s:%d) " fmt "\n", \ __func__, __LINE__, ##__VA_ARGS__) #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "xenbus.h" /* device// => - */ static int frontend_bus_id(char bus_id[XEN_BUS_ID_SIZE], const char *nodename) { nodename = strchr(nodename, '/'); if (!nodename || strlen(nodename + 1) >= XEN_BUS_ID_SIZE) { pr_warn("bad frontend %s\n", nodename); return -EINVAL; } strlcpy(bus_id, nodename + 1, XEN_BUS_ID_SIZE); if (!strchr(bus_id, '/')) { pr_warn("bus_id %s no slash\n", bus_id); return -EINVAL; } *strchr(bus_id, '/') = '-'; return 0; } /* device// */ static int xenbus_probe_frontend(struct xen_bus_type *bus, const char *type, const char *name) { char *nodename; int err; /* ignore console/0 */ if (!strncmp(type, "console", 7) && !strncmp(name, "0", 1)) { DPRINTK("Ignoring buggy device entry console/0"); return 0; } nodename = kasprintf(GFP_KERNEL, "%s/%s/%s", bus->root, type, name); if (!nodename) return -ENOMEM; DPRINTK("%s", nodename); err = xenbus_probe_node(bus, type, nodename); kfree(nodename); return err; } static int xenbus_uevent_frontend(struct device *_dev, struct kobj_uevent_env *env) { struct xenbus_device *dev = to_xenbus_device(_dev); if (add_uevent_var(env, "MODALIAS=xen:%s", dev->devicetype)) return -ENOMEM; return 0; } static void backend_changed(struct xenbus_watch *watch, const char *path, const char *token) { xenbus_otherend_changed(watch, path, token, 1); } static void xenbus_frontend_delayed_resume(struct work_struct *w) { struct xenbus_device *xdev = container_of(w, struct xenbus_device, work); xenbus_dev_resume(&xdev->dev); } static int xenbus_frontend_dev_resume(struct device *dev) { /* * If xenstored is running in this domain, we cannot access the backend * state at the moment, so we need to defer xenbus_dev_resume */ if (xen_store_domain_type == XS_LOCAL) { struct xenbus_device *xdev = to_xenbus_device(dev); schedule_work(&xdev->work); return 0; } return xenbus_dev_resume(dev); } static int xenbus_frontend_dev_probe(struct device *dev) { if (xen_store_domain_type == XS_LOCAL) { struct xenbus_device *xdev = to_xenbus_device(dev); INIT_WORK(&xdev->work, xenbus_frontend_delayed_resume); } return xenbus_dev_probe(dev); } static void xenbus_frontend_dev_shutdown(struct device *_dev) { struct xenbus_device *dev = to_xenbus_device(_dev); unsigned long timeout = 5*HZ; DPRINTK("%s", dev->nodename); get_device(&dev->dev); if (dev->state != XenbusStateConnected) { pr_info("%s: %s: %s != Connected, skipping\n", __func__, dev->nodename, xenbus_strstate(dev->state)); goto out; } xenbus_switch_state(dev, XenbusStateClosing); timeout = wait_for_completion_timeout(&dev->down, timeout); if (!timeout) pr_info("%s: %s timeout closing device\n", __func__, dev->nodename); out: put_device(&dev->dev); } static const struct dev_pm_ops xenbus_pm_ops = { .suspend = xenbus_dev_suspend, .resume = xenbus_frontend_dev_resume, .freeze = xenbus_dev_suspend, .thaw = xenbus_dev_cancel, .restore = xenbus_dev_resume, }; static struct xen_bus_type xenbus_frontend = { .root = "device", .levels = 2, /* device/type/ */ .get_bus_id = frontend_bus_id, .probe = xenbus_probe_frontend, .otherend_changed = backend_changed, .bus = { .name = "xen", .match = xenbus_match, .uevent = xenbus_uevent_frontend, .probe = xenbus_frontend_dev_probe, .remove = xenbus_dev_remove, .shutdown = xenbus_frontend_dev_shutdown, .dev_groups = xenbus_dev_groups, .pm = &xenbus_pm_ops, }, }; static void frontend_changed(struct xenbus_watch *watch, const char *path, const char *token) { DPRINTK(""); xenbus_dev_changed(path, &xenbus_frontend); } /* We watch for devices appearing and vanishing. */ static struct xenbus_watch fe_watch = { .node = "device", .callback = frontend_changed, }; static int read_backend_details(struct xenbus_device *xendev) { return xenbus_read_otherend_details(xendev, "backend-id", "backend"); } static int is_device_connecting(struct device *dev, void *data, bool ignore_nonessential) { struct xenbus_device *xendev = to_xenbus_device(dev); struct device_driver *drv = data; struct xenbus_driver *xendrv; /* * A device with no driver will never connect. We care only about * devices which should currently be in the process of connecting. */ if (!dev->driver) return 0; /* Is this search limited to a particular driver? */ if (drv && (dev->driver != drv)) return 0; if (ignore_nonessential) { /* With older QEMU, for PVonHVM guests the guest config files * could contain: vfb = [ 'vnc=1, vnclisten=0.0.0.0'] * which is nonsensical as there is no PV FB (there can be * a PVKB) running as HVM guest. */ if ((strncmp(xendev->nodename, "device/vkbd", 11) == 0)) return 0; if ((strncmp(xendev->nodename, "device/vfb", 10) == 0)) return 0; } xendrv = to_xenbus_driver(dev->driver); return (xendev->state < XenbusStateConnected || (xendev->state == XenbusStateConnected && xendrv->is_ready && !xendrv->is_ready(xendev))); } static int essential_device_connecting(struct device *dev, void *data) { return is_device_connecting(dev, data, true /* ignore PV[KBB+FB] */); } static int non_essential_device_connecting(struct device *dev, void *data) { return is_device_connecting(dev, data, false); } static int exists_essential_connecting_device(struct device_driver *drv) { return bus_for_each_dev(&xenbus_frontend.bus, NULL, drv, essential_device_connecting); } static int exists_non_essential_connecting_device(struct device_driver *drv) { return bus_for_each_dev(&xenbus_frontend.bus, NULL, drv, non_essential_device_connecting); } static int print_device_status(struct device *dev, void *data) { struct xenbus_device *xendev = to_xenbus_device(dev); struct device_driver *drv = data; /* Is this operation limited to a particular driver? */ if (drv && (dev->driver != drv)) return 0; if (!dev->driver) { /* Information only: is this too noisy? */ pr_info("Device with no driver: %s\n", xendev->nodename); } else if (xendev->state < XenbusStateConnected) { enum xenbus_state rstate = XenbusStateUnknown; if (xendev->otherend) rstate = xenbus_read_driver_state(xendev->otherend); pr_warn("Timeout connecting to device: %s (local state %d, remote state %d)\n", xendev->nodename, xendev->state, rstate); } return 0; } /* We only wait for device setup after most initcalls have run. */ static int ready_to_wait_for_devices; static bool wait_loop(unsigned long start, unsigned int max_delay, unsigned int *seconds_waited) { if (time_after(jiffies, start + (*seconds_waited+5)*HZ)) { if (!*seconds_waited) pr_warn("Waiting for devices to initialise: "); *seconds_waited += 5; pr_cont("%us...", max_delay - *seconds_waited); if (*seconds_waited == max_delay) { pr_cont("\n"); return true; } } schedule_timeout_interruptible(HZ/10); return false; } /* * On a 5-minute timeout, wait for all devices currently configured. We need * to do this to guarantee that the filesystems and / or network devices * needed for boot are available, before we can allow the boot to proceed. * * This needs to be on a late_initcall, to happen after the frontend device * drivers have been initialised, but before the root fs is mounted. * * A possible improvement here would be to have the tools add a per-device * flag to the store entry, indicating whether it is needed at boot time. * This would allow people who knew what they were doing to accelerate their * boot slightly, but of course needs tools or manual intervention to set up * those flags correctly. */ static void wait_for_devices(struct xenbus_driver *xendrv) { unsigned long start = jiffies; struct device_driver *drv = xendrv ? &xendrv->driver : NULL; unsigned int seconds_waited = 0; if (!ready_to_wait_for_devices || !xen_domain()) return; while (exists_non_essential_connecting_device(drv)) if (wait_loop(start, 30, &seconds_waited)) break; /* Skips PVKB and PVFB check.*/ while (exists_essential_connecting_device(drv)) if (wait_loop(start, 270, &seconds_waited)) break; if (seconds_waited) printk("\n"); bus_for_each_dev(&xenbus_frontend.bus, NULL, drv, print_device_status); } int __xenbus_register_frontend(struct xenbus_driver *drv, struct module *owner, const char *mod_name) { int ret; drv->read_otherend_details = read_backend_details; ret = xenbus_register_driver_common(drv, &xenbus_frontend, owner, mod_name); if (ret) return ret; /* If this driver is loaded as a module wait for devices to attach. */ wait_for_devices(drv); return 0; } EXPORT_SYMBOL_GPL(__xenbus_register_frontend); static DECLARE_WAIT_QUEUE_HEAD(backend_state_wq); static int backend_state; static void xenbus_reset_backend_state_changed(struct xenbus_watch *w, const char *path, const char *token) { if (xenbus_scanf(XBT_NIL, path, "", "%i", &backend_state) != 1) backend_state = XenbusStateUnknown; printk(KERN_DEBUG "XENBUS: backend %s %s\n", path, xenbus_strstate(backend_state)); wake_up(&backend_state_wq); } static void xenbus_reset_wait_for_backend(char *be, int expected) { long timeout; timeout = wait_event_interruptible_timeout(backend_state_wq, backend_state == expected, 5 * HZ); if (timeout <= 0) pr_info("backend %s timed out\n", be); } /* * Reset frontend if it is in Connected or Closed state. * Wait for backend to catch up. * State Connected happens during kdump, Closed after kexec. */ static void xenbus_reset_frontend(char *fe, char *be, int be_state) { struct xenbus_watch be_watch; printk(KERN_DEBUG "XENBUS: backend %s %s\n", be, xenbus_strstate(be_state)); memset(&be_watch, 0, sizeof(be_watch)); be_watch.node = kasprintf(GFP_NOIO | __GFP_HIGH, "%s/state", be); if (!be_watch.node) return; be_watch.callback = xenbus_reset_backend_state_changed; backend_state = XenbusStateUnknown; pr_info("triggering reconnect on %s\n", be); register_xenbus_watch(&be_watch); /* fall through to forward backend to state XenbusStateInitialising */ switch (be_state) { case XenbusStateConnected: xenbus_printf(XBT_NIL, fe, "state", "%d", XenbusStateClosing); xenbus_reset_wait_for_backend(be, XenbusStateClosing); fallthrough; case XenbusStateClosing: xenbus_printf(XBT_NIL, fe, "state", "%d", XenbusStateClosed); xenbus_reset_wait_for_backend(be, XenbusStateClosed); fallthrough; case XenbusStateClosed: xenbus_printf(XBT_NIL, fe, "state", "%d", XenbusStateInitialising); xenbus_reset_wait_for_backend(be, XenbusStateInitWait); } unregister_xenbus_watch(&be_watch); pr_info("reconnect done on %s\n", be); kfree(be_watch.node); } static void xenbus_check_frontend(char *class, char *dev) { int be_state, fe_state, err; char *backend, *frontend; frontend = kasprintf(GFP_NOIO | __GFP_HIGH, "device/%s/%s", class, dev); if (!frontend) return; err = xenbus_scanf(XBT_NIL, frontend, "state", "%i", &fe_state); if (err != 1) goto out; switch (fe_state) { case XenbusStateConnected: case XenbusStateClosed: printk(KERN_DEBUG "XENBUS: frontend %s %s\n", frontend, xenbus_strstate(fe_state)); backend = xenbus_read(XBT_NIL, frontend, "backend", NULL); if (!backend || IS_ERR(backend)) goto out; err = xenbus_scanf(XBT_NIL, backend, "state", "%i", &be_state); if (err == 1) xenbus_reset_frontend(frontend, backend, be_state); kfree(backend); break; default: break; } out: kfree(frontend); } static void xenbus_reset_state(void) { char **devclass, **dev; int devclass_n, dev_n; int i, j; devclass = xenbus_directory(XBT_NIL, "device", "", &devclass_n); if (IS_ERR(devclass)) return; for (i = 0; i < devclass_n; i++) { dev = xenbus_directory(XBT_NIL, "device", devclass[i], &dev_n); if (IS_ERR(dev)) continue; for (j = 0; j < dev_n; j++) xenbus_check_frontend(devclass[i], dev[j]); kfree(dev); } kfree(devclass); } static int frontend_probe_and_watch(struct notifier_block *notifier, unsigned long event, void *data) { /* reset devices in Connected or Closed state */ if (xen_hvm_domain()) xenbus_reset_state(); /* Enumerate devices in xenstore and watch for changes. */ xenbus_probe_devices(&xenbus_frontend); register_xenbus_watch(&fe_watch); return NOTIFY_DONE; } static int __init xenbus_probe_frontend_init(void) { static struct notifier_block xenstore_notifier = { .notifier_call = frontend_probe_and_watch }; int err; DPRINTK(""); /* Register ourselves with the kernel bus subsystem */ err = bus_register(&xenbus_frontend.bus); if (err) return err; register_xenstore_notifier(&xenstore_notifier); return 0; } subsys_initcall(xenbus_probe_frontend_init); #ifndef MODULE static int __init boot_wait_for_devices(void) { if (!xen_has_pv_devices()) return -ENODEV; ready_to_wait_for_devices = 1; wait_for_devices(NULL); return 0; } late_initcall(boot_wait_for_devices); #endif MODULE_LICENSE("GPL");