1#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
2
3#define DPRINTK(fmt, ...)				\
4	pr_debug("(%s:%d) " fmt "\n",			\
5		 __func__, __LINE__, ##__VA_ARGS__)
6
7#include <linux/kernel.h>
8#include <linux/err.h>
9#include <linux/string.h>
10#include <linux/ctype.h>
11#include <linux/fcntl.h>
12#include <linux/mm.h>
13#include <linux/proc_fs.h>
14#include <linux/notifier.h>
15#include <linux/kthread.h>
16#include <linux/mutex.h>
17#include <linux/io.h>
18#include <linux/module.h>
19
20#include <asm/page.h>
21#include <asm/pgtable.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_comms.h"
31#include "xenbus_probe.h"
32
33
34static struct workqueue_struct *xenbus_frontend_wq;
35
36/* device/<type>/<id> => <type>-<id> */
37static int frontend_bus_id(char bus_id[XEN_BUS_ID_SIZE], const char *nodename)
38{
39	nodename = strchr(nodename, '/');
40	if (!nodename || strlen(nodename + 1) >= XEN_BUS_ID_SIZE) {
41		pr_warn("bad frontend %s\n", nodename);
42		return -EINVAL;
43	}
44
45	strlcpy(bus_id, nodename + 1, XEN_BUS_ID_SIZE);
46	if (!strchr(bus_id, '/')) {
47		pr_warn("bus_id %s no slash\n", bus_id);
48		return -EINVAL;
49	}
50	*strchr(bus_id, '/') = '-';
51	return 0;
52}
53
54/* device/<typename>/<name> */
55static int xenbus_probe_frontend(struct xen_bus_type *bus, const char *type,
56				 const char *name)
57{
58	char *nodename;
59	int err;
60
61	/* ignore console/0 */
62	if (!strncmp(type, "console", 7) && !strncmp(name, "0", 1)) {
63		DPRINTK("Ignoring buggy device entry console/0");
64		return 0;
65	}
66
67	nodename = kasprintf(GFP_KERNEL, "%s/%s/%s", bus->root, type, name);
68	if (!nodename)
69		return -ENOMEM;
70
71	DPRINTK("%s", nodename);
72
73	err = xenbus_probe_node(bus, type, nodename);
74	kfree(nodename);
75	return err;
76}
77
78static int xenbus_uevent_frontend(struct device *_dev,
79				  struct kobj_uevent_env *env)
80{
81	struct xenbus_device *dev = to_xenbus_device(_dev);
82
83	if (add_uevent_var(env, "MODALIAS=xen:%s", dev->devicetype))
84		return -ENOMEM;
85
86	return 0;
87}
88
89
90static void backend_changed(struct xenbus_watch *watch,
91			    const char **vec, unsigned int len)
92{
93	xenbus_otherend_changed(watch, vec, len, 1);
94}
95
96static void xenbus_frontend_delayed_resume(struct work_struct *w)
97{
98	struct xenbus_device *xdev = container_of(w, struct xenbus_device, work);
99
100	xenbus_dev_resume(&xdev->dev);
101}
102
103static int xenbus_frontend_dev_resume(struct device *dev)
104{
105	/*
106	 * If xenstored is running in this domain, we cannot access the backend
107	 * state at the moment, so we need to defer xenbus_dev_resume
108	 */
109	if (xen_store_domain_type == XS_LOCAL) {
110		struct xenbus_device *xdev = to_xenbus_device(dev);
111
112		if (!xenbus_frontend_wq) {
113			pr_err("%s: no workqueue to process delayed resume\n",
114			       xdev->nodename);
115			return -EFAULT;
116		}
117
118		queue_work(xenbus_frontend_wq, &xdev->work);
119
120		return 0;
121	}
122
123	return xenbus_dev_resume(dev);
124}
125
126static int xenbus_frontend_dev_probe(struct device *dev)
127{
128	if (xen_store_domain_type == XS_LOCAL) {
129		struct xenbus_device *xdev = to_xenbus_device(dev);
130		INIT_WORK(&xdev->work, xenbus_frontend_delayed_resume);
131	}
132
133	return xenbus_dev_probe(dev);
134}
135
136static const struct dev_pm_ops xenbus_pm_ops = {
137	.suspend	= xenbus_dev_suspend,
138	.resume		= xenbus_frontend_dev_resume,
139	.freeze		= xenbus_dev_suspend,
140	.thaw		= xenbus_dev_cancel,
141	.restore	= xenbus_dev_resume,
142};
143
144static struct xen_bus_type xenbus_frontend = {
145	.root = "device",
146	.levels = 2,		/* device/type/<id> */
147	.get_bus_id = frontend_bus_id,
148	.probe = xenbus_probe_frontend,
149	.otherend_changed = backend_changed,
150	.bus = {
151		.name		= "xen",
152		.match		= xenbus_match,
153		.uevent		= xenbus_uevent_frontend,
154		.probe		= xenbus_frontend_dev_probe,
155		.remove		= xenbus_dev_remove,
156		.shutdown	= xenbus_dev_shutdown,
157		.dev_groups	= xenbus_dev_groups,
158
159		.pm		= &xenbus_pm_ops,
160	},
161};
162
163static void frontend_changed(struct xenbus_watch *watch,
164			     const char **vec, unsigned int len)
165{
166	DPRINTK("");
167
168	xenbus_dev_changed(vec[XS_WATCH_PATH], &xenbus_frontend);
169}
170
171
172/* We watch for devices appearing and vanishing. */
173static struct xenbus_watch fe_watch = {
174	.node = "device",
175	.callback = frontend_changed,
176};
177
178static int read_backend_details(struct xenbus_device *xendev)
179{
180	return xenbus_read_otherend_details(xendev, "backend-id", "backend");
181}
182
183static int is_device_connecting(struct device *dev, void *data, bool ignore_nonessential)
184{
185	struct xenbus_device *xendev = to_xenbus_device(dev);
186	struct device_driver *drv = data;
187	struct xenbus_driver *xendrv;
188
189	/*
190	 * A device with no driver will never connect. We care only about
191	 * devices which should currently be in the process of connecting.
192	 */
193	if (!dev->driver)
194		return 0;
195
196	/* Is this search limited to a particular driver? */
197	if (drv && (dev->driver != drv))
198		return 0;
199
200	if (ignore_nonessential) {
201		/* With older QEMU, for PVonHVM guests the guest config files
202		 * could contain: vfb = [ 'vnc=1, vnclisten=0.0.0.0']
203		 * which is nonsensical as there is no PV FB (there can be
204		 * a PVKB) running as HVM guest. */
205
206		if ((strncmp(xendev->nodename, "device/vkbd", 11) == 0))
207			return 0;
208
209		if ((strncmp(xendev->nodename, "device/vfb", 10) == 0))
210			return 0;
211	}
212	xendrv = to_xenbus_driver(dev->driver);
213	return (xendev->state < XenbusStateConnected ||
214		(xendev->state == XenbusStateConnected &&
215		 xendrv->is_ready && !xendrv->is_ready(xendev)));
216}
217static int essential_device_connecting(struct device *dev, void *data)
218{
219	return is_device_connecting(dev, data, true /* ignore PV[KBB+FB] */);
220}
221static int non_essential_device_connecting(struct device *dev, void *data)
222{
223	return is_device_connecting(dev, data, false);
224}
225
226static int exists_essential_connecting_device(struct device_driver *drv)
227{
228	return bus_for_each_dev(&xenbus_frontend.bus, NULL, drv,
229				essential_device_connecting);
230}
231static int exists_non_essential_connecting_device(struct device_driver *drv)
232{
233	return bus_for_each_dev(&xenbus_frontend.bus, NULL, drv,
234				non_essential_device_connecting);
235}
236
237static int print_device_status(struct device *dev, void *data)
238{
239	struct xenbus_device *xendev = to_xenbus_device(dev);
240	struct device_driver *drv = data;
241
242	/* Is this operation limited to a particular driver? */
243	if (drv && (dev->driver != drv))
244		return 0;
245
246	if (!dev->driver) {
247		/* Information only: is this too noisy? */
248		pr_info("Device with no driver: %s\n", xendev->nodename);
249	} else if (xendev->state < XenbusStateConnected) {
250		enum xenbus_state rstate = XenbusStateUnknown;
251		if (xendev->otherend)
252			rstate = xenbus_read_driver_state(xendev->otherend);
253		pr_warn("Timeout connecting to device: %s (local state %d, remote state %d)\n",
254			xendev->nodename, xendev->state, rstate);
255	}
256
257	return 0;
258}
259
260/* We only wait for device setup after most initcalls have run. */
261static int ready_to_wait_for_devices;
262
263static bool wait_loop(unsigned long start, unsigned int max_delay,
264		     unsigned int *seconds_waited)
265{
266	if (time_after(jiffies, start + (*seconds_waited+5)*HZ)) {
267		if (!*seconds_waited)
268			pr_warn("Waiting for devices to initialise: ");
269		*seconds_waited += 5;
270		pr_cont("%us...", max_delay - *seconds_waited);
271		if (*seconds_waited == max_delay) {
272			pr_cont("\n");
273			return true;
274		}
275	}
276
277	schedule_timeout_interruptible(HZ/10);
278
279	return false;
280}
281/*
282 * On a 5-minute timeout, wait for all devices currently configured.  We need
283 * to do this to guarantee that the filesystems and / or network devices
284 * needed for boot are available, before we can allow the boot to proceed.
285 *
286 * This needs to be on a late_initcall, to happen after the frontend device
287 * drivers have been initialised, but before the root fs is mounted.
288 *
289 * A possible improvement here would be to have the tools add a per-device
290 * flag to the store entry, indicating whether it is needed at boot time.
291 * This would allow people who knew what they were doing to accelerate their
292 * boot slightly, but of course needs tools or manual intervention to set up
293 * those flags correctly.
294 */
295static void wait_for_devices(struct xenbus_driver *xendrv)
296{
297	unsigned long start = jiffies;
298	struct device_driver *drv = xendrv ? &xendrv->driver : NULL;
299	unsigned int seconds_waited = 0;
300
301	if (!ready_to_wait_for_devices || !xen_domain())
302		return;
303
304	while (exists_non_essential_connecting_device(drv))
305		if (wait_loop(start, 30, &seconds_waited))
306			break;
307
308	/* Skips PVKB and PVFB check.*/
309	while (exists_essential_connecting_device(drv))
310		if (wait_loop(start, 270, &seconds_waited))
311			break;
312
313	if (seconds_waited)
314		printk("\n");
315
316	bus_for_each_dev(&xenbus_frontend.bus, NULL, drv,
317			 print_device_status);
318}
319
320int __xenbus_register_frontend(struct xenbus_driver *drv, struct module *owner,
321			       const char *mod_name)
322{
323	int ret;
324
325	drv->read_otherend_details = read_backend_details;
326
327	ret = xenbus_register_driver_common(drv, &xenbus_frontend,
328					    owner, mod_name);
329	if (ret)
330		return ret;
331
332	/* If this driver is loaded as a module wait for devices to attach. */
333	wait_for_devices(drv);
334
335	return 0;
336}
337EXPORT_SYMBOL_GPL(__xenbus_register_frontend);
338
339static DECLARE_WAIT_QUEUE_HEAD(backend_state_wq);
340static int backend_state;
341
342static void xenbus_reset_backend_state_changed(struct xenbus_watch *w,
343					const char **v, unsigned int l)
344{
345	xenbus_scanf(XBT_NIL, v[XS_WATCH_PATH], "", "%i", &backend_state);
346	printk(KERN_DEBUG "XENBUS: backend %s %s\n",
347			v[XS_WATCH_PATH], xenbus_strstate(backend_state));
348	wake_up(&backend_state_wq);
349}
350
351static void xenbus_reset_wait_for_backend(char *be, int expected)
352{
353	long timeout;
354	timeout = wait_event_interruptible_timeout(backend_state_wq,
355			backend_state == expected, 5 * HZ);
356	if (timeout <= 0)
357		pr_info("backend %s timed out\n", be);
358}
359
360/*
361 * Reset frontend if it is in Connected or Closed state.
362 * Wait for backend to catch up.
363 * State Connected happens during kdump, Closed after kexec.
364 */
365static void xenbus_reset_frontend(char *fe, char *be, int be_state)
366{
367	struct xenbus_watch be_watch;
368
369	printk(KERN_DEBUG "XENBUS: backend %s %s\n",
370			be, xenbus_strstate(be_state));
371
372	memset(&be_watch, 0, sizeof(be_watch));
373	be_watch.node = kasprintf(GFP_NOIO | __GFP_HIGH, "%s/state", be);
374	if (!be_watch.node)
375		return;
376
377	be_watch.callback = xenbus_reset_backend_state_changed;
378	backend_state = XenbusStateUnknown;
379
380	pr_info("triggering reconnect on %s\n", be);
381	register_xenbus_watch(&be_watch);
382
383	/* fall through to forward backend to state XenbusStateInitialising */
384	switch (be_state) {
385	case XenbusStateConnected:
386		xenbus_printf(XBT_NIL, fe, "state", "%d", XenbusStateClosing);
387		xenbus_reset_wait_for_backend(be, XenbusStateClosing);
388
389	case XenbusStateClosing:
390		xenbus_printf(XBT_NIL, fe, "state", "%d", XenbusStateClosed);
391		xenbus_reset_wait_for_backend(be, XenbusStateClosed);
392
393	case XenbusStateClosed:
394		xenbus_printf(XBT_NIL, fe, "state", "%d", XenbusStateInitialising);
395		xenbus_reset_wait_for_backend(be, XenbusStateInitWait);
396	}
397
398	unregister_xenbus_watch(&be_watch);
399	pr_info("reconnect done on %s\n", be);
400	kfree(be_watch.node);
401}
402
403static void xenbus_check_frontend(char *class, char *dev)
404{
405	int be_state, fe_state, err;
406	char *backend, *frontend;
407
408	frontend = kasprintf(GFP_NOIO | __GFP_HIGH, "device/%s/%s", class, dev);
409	if (!frontend)
410		return;
411
412	err = xenbus_scanf(XBT_NIL, frontend, "state", "%i", &fe_state);
413	if (err != 1)
414		goto out;
415
416	switch (fe_state) {
417	case XenbusStateConnected:
418	case XenbusStateClosed:
419		printk(KERN_DEBUG "XENBUS: frontend %s %s\n",
420				frontend, xenbus_strstate(fe_state));
421		backend = xenbus_read(XBT_NIL, frontend, "backend", NULL);
422		if (!backend || IS_ERR(backend))
423			goto out;
424		err = xenbus_scanf(XBT_NIL, backend, "state", "%i", &be_state);
425		if (err == 1)
426			xenbus_reset_frontend(frontend, backend, be_state);
427		kfree(backend);
428		break;
429	default:
430		break;
431	}
432out:
433	kfree(frontend);
434}
435
436static void xenbus_reset_state(void)
437{
438	char **devclass, **dev;
439	int devclass_n, dev_n;
440	int i, j;
441
442	devclass = xenbus_directory(XBT_NIL, "device", "", &devclass_n);
443	if (IS_ERR(devclass))
444		return;
445
446	for (i = 0; i < devclass_n; i++) {
447		dev = xenbus_directory(XBT_NIL, "device", devclass[i], &dev_n);
448		if (IS_ERR(dev))
449			continue;
450		for (j = 0; j < dev_n; j++)
451			xenbus_check_frontend(devclass[i], dev[j]);
452		kfree(dev);
453	}
454	kfree(devclass);
455}
456
457static int frontend_probe_and_watch(struct notifier_block *notifier,
458				   unsigned long event,
459				   void *data)
460{
461	/* reset devices in Connected or Closed state */
462	if (xen_hvm_domain())
463		xenbus_reset_state();
464	/* Enumerate devices in xenstore and watch for changes. */
465	xenbus_probe_devices(&xenbus_frontend);
466	register_xenbus_watch(&fe_watch);
467
468	return NOTIFY_DONE;
469}
470
471
472static int __init xenbus_probe_frontend_init(void)
473{
474	static struct notifier_block xenstore_notifier = {
475		.notifier_call = frontend_probe_and_watch
476	};
477	int err;
478
479	DPRINTK("");
480
481	/* Register ourselves with the kernel bus subsystem */
482	err = bus_register(&xenbus_frontend.bus);
483	if (err)
484		return err;
485
486	register_xenstore_notifier(&xenstore_notifier);
487
488	if (xen_store_domain_type == XS_LOCAL) {
489		xenbus_frontend_wq = create_workqueue("xenbus_frontend");
490		if (!xenbus_frontend_wq)
491			pr_warn("create xenbus frontend workqueue failed, S3 resume is likely to fail\n");
492	}
493
494	return 0;
495}
496subsys_initcall(xenbus_probe_frontend_init);
497
498#ifndef MODULE
499static int __init boot_wait_for_devices(void)
500{
501	if (!xen_has_pv_devices())
502		return -ENODEV;
503
504	ready_to_wait_for_devices = 1;
505	wait_for_devices(NULL);
506	return 0;
507}
508
509late_initcall(boot_wait_for_devices);
510#endif
511
512MODULE_LICENSE("GPL");
513