diff options
Diffstat (limited to 'drivers/xen/xenbus/xenbus_probe_frontend.c')
| -rw-r--r-- | drivers/xen/xenbus/xenbus_probe_frontend.c | 516 |
1 files changed, 516 insertions, 0 deletions
diff --git a/drivers/xen/xenbus/xenbus_probe_frontend.c b/drivers/xen/xenbus/xenbus_probe_frontend.c new file mode 100644 index 000000000..f44d5a643 --- /dev/null +++ b/drivers/xen/xenbus/xenbus_probe_frontend.c @@ -0,0 +1,516 @@ +// 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 <linux/kernel.h> +#include <linux/err.h> +#include <linux/string.h> +#include <linux/ctype.h> +#include <linux/fcntl.h> +#include <linux/mm.h> +#include <linux/proc_fs.h> +#include <linux/notifier.h> +#include <linux/kthread.h> +#include <linux/mutex.h> +#include <linux/io.h> +#include <linux/module.h> + +#include <asm/page.h> +#include <asm/xen/hypervisor.h> +#include <xen/xenbus.h> +#include <xen/events.h> +#include <xen/page.h> +#include <xen/xen.h> + +#include <xen/platform_pci.h> + +#include "xenbus.h" + + + +/* device/<type>/<id> => <type>-<id> */ +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; + } + + strscpy(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/<typename>/<name> */ +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/<id> */ + .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; + + xendrv = to_xenbus_driver(dev->driver); + + if (ignore_nonessential && xendrv->not_essential) + return 0; + + 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"); |