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
25#include <xen/platform_pci.h>
26
27#include "xenbus_comms.h"
28#include "xenbus_probe.h"
29
30
31/* device/<type>/<id> => <type>-<id> */
32static int frontend_bus_id(char bus_id[XEN_BUS_ID_SIZE], const char *nodename)
33{
34	nodename = strchr(nodename, '/');
35	if (!nodename || strlen(nodename + 1) >= XEN_BUS_ID_SIZE) {
36		printk(KERN_WARNING "XENBUS: bad frontend %s\n", nodename);
37		return -EINVAL;
38	}
39
40	strlcpy(bus_id, nodename + 1, XEN_BUS_ID_SIZE);
41	if (!strchr(bus_id, '/')) {
42		printk(KERN_WARNING "XENBUS: bus_id %s no slash\n", bus_id);
43		return -EINVAL;
44	}
45	*strchr(bus_id, '/') = '-';
46	return 0;
47}
48
49/* device/<typename>/<name> */
50static int xenbus_probe_frontend(struct xen_bus_type *bus, const char *type,
51				 const char *name)
52{
53	char *nodename;
54	int err;
55
56	/* ignore console/0 */
57	if (!strncmp(type, "console", 7) && !strncmp(name, "0", 1)) {
58		DPRINTK("Ignoring buggy device entry console/0");
59		return 0;
60	}
61
62	nodename = kasprintf(GFP_KERNEL, "%s/%s/%s", bus->root, type, name);
63	if (!nodename)
64		return -ENOMEM;
65
66	DPRINTK("%s", nodename);
67
68	err = xenbus_probe_node(bus, type, nodename);
69	kfree(nodename);
70	return err;
71}
72
73static int xenbus_uevent_frontend(struct device *_dev,
74				  struct kobj_uevent_env *env)
75{
76	struct xenbus_device *dev = to_xenbus_device(_dev);
77
78	if (add_uevent_var(env, "MODALIAS=xen:%s", dev->devicetype))
79		return -ENOMEM;
80
81	return 0;
82}
83
84
85static void backend_changed(struct xenbus_watch *watch,
86			    const char **vec, unsigned int len)
87{
88	xenbus_otherend_changed(watch, vec, len, 1);
89}
90
91static const struct dev_pm_ops xenbus_pm_ops = {
92	.suspend	= xenbus_dev_suspend,
93	.resume		= xenbus_dev_resume,
94	.freeze		= xenbus_dev_suspend,
95	.thaw		= xenbus_dev_cancel,
96	.restore	= xenbus_dev_resume,
97};
98
99static struct xen_bus_type xenbus_frontend = {
100	.root = "device",
101	.levels = 2,		/* device/type/<id> */
102	.get_bus_id = frontend_bus_id,
103	.probe = xenbus_probe_frontend,
104	.otherend_changed = backend_changed,
105	.bus = {
106		.name		= "xen",
107		.match		= xenbus_match,
108		.uevent		= xenbus_uevent_frontend,
109		.probe		= xenbus_dev_probe,
110		.remove		= xenbus_dev_remove,
111		.shutdown	= xenbus_dev_shutdown,
112		.dev_attrs	= xenbus_dev_attrs,
113
114		.pm		= &xenbus_pm_ops,
115	},
116};
117
118static void frontend_changed(struct xenbus_watch *watch,
119			     const char **vec, unsigned int len)
120{
121	DPRINTK("");
122
123	xenbus_dev_changed(vec[XS_WATCH_PATH], &xenbus_frontend);
124}
125
126
127/* We watch for devices appearing and vanishing. */
128static struct xenbus_watch fe_watch = {
129	.node = "device",
130	.callback = frontend_changed,
131};
132
133static int read_backend_details(struct xenbus_device *xendev)
134{
135	return xenbus_read_otherend_details(xendev, "backend-id", "backend");
136}
137
138static int is_device_connecting(struct device *dev, void *data, bool ignore_nonessential)
139{
140	struct xenbus_device *xendev = to_xenbus_device(dev);
141	struct device_driver *drv = data;
142	struct xenbus_driver *xendrv;
143
144	/*
145	 * A device with no driver will never connect. We care only about
146	 * devices which should currently be in the process of connecting.
147	 */
148	if (!dev->driver)
149		return 0;
150
151	/* Is this search limited to a particular driver? */
152	if (drv && (dev->driver != drv))
153		return 0;
154
155	if (ignore_nonessential) {
156		/* With older QEMU, for PVonHVM guests the guest config files
157		 * could contain: vfb = [ 'vnc=1, vnclisten=0.0.0.0']
158		 * which is nonsensical as there is no PV FB (there can be
159		 * a PVKB) running as HVM guest. */
160
161		if ((strncmp(xendev->nodename, "device/vkbd", 11) == 0))
162			return 0;
163
164		if ((strncmp(xendev->nodename, "device/vfb", 10) == 0))
165			return 0;
166	}
167	xendrv = to_xenbus_driver(dev->driver);
168	return (xendev->state < XenbusStateConnected ||
169		(xendev->state == XenbusStateConnected &&
170		 xendrv->is_ready && !xendrv->is_ready(xendev)));
171}
172static int essential_device_connecting(struct device *dev, void *data)
173{
174	return is_device_connecting(dev, data, true /* ignore PV[KBB+FB] */);
175}
176static int non_essential_device_connecting(struct device *dev, void *data)
177{
178	return is_device_connecting(dev, data, false);
179}
180
181static int exists_essential_connecting_device(struct device_driver *drv)
182{
183	return bus_for_each_dev(&xenbus_frontend.bus, NULL, drv,
184				essential_device_connecting);
185}
186static int exists_non_essential_connecting_device(struct device_driver *drv)
187{
188	return bus_for_each_dev(&xenbus_frontend.bus, NULL, drv,
189				non_essential_device_connecting);
190}
191
192static int print_device_status(struct device *dev, void *data)
193{
194	struct xenbus_device *xendev = to_xenbus_device(dev);
195	struct device_driver *drv = data;
196
197	/* Is this operation limited to a particular driver? */
198	if (drv && (dev->driver != drv))
199		return 0;
200
201	if (!dev->driver) {
202		/* Information only: is this too noisy? */
203		printk(KERN_INFO "XENBUS: Device with no driver: %s\n",
204		       xendev->nodename);
205	} else if (xendev->state < XenbusStateConnected) {
206		enum xenbus_state rstate = XenbusStateUnknown;
207		if (xendev->otherend)
208			rstate = xenbus_read_driver_state(xendev->otherend);
209		printk(KERN_WARNING "XENBUS: Timeout connecting "
210		       "to device: %s (local state %d, remote state %d)\n",
211		       xendev->nodename, xendev->state, rstate);
212	}
213
214	return 0;
215}
216
217/* We only wait for device setup after most initcalls have run. */
218static int ready_to_wait_for_devices;
219
220static bool wait_loop(unsigned long start, unsigned int max_delay,
221		     unsigned int *seconds_waited)
222{
223	if (time_after(jiffies, start + (*seconds_waited+5)*HZ)) {
224		if (!*seconds_waited)
225			printk(KERN_WARNING "XENBUS: Waiting for "
226			       "devices to initialise: ");
227		*seconds_waited += 5;
228		printk("%us...", max_delay - *seconds_waited);
229		if (*seconds_waited == max_delay)
230			return true;
231	}
232
233	schedule_timeout_interruptible(HZ/10);
234
235	return false;
236}
237/*
238 * On a 5-minute timeout, wait for all devices currently configured.  We need
239 * to do this to guarantee that the filesystems and / or network devices
240 * needed for boot are available, before we can allow the boot to proceed.
241 *
242 * This needs to be on a late_initcall, to happen after the frontend device
243 * drivers have been initialised, but before the root fs is mounted.
244 *
245 * A possible improvement here would be to have the tools add a per-device
246 * flag to the store entry, indicating whether it is needed at boot time.
247 * This would allow people who knew what they were doing to accelerate their
248 * boot slightly, but of course needs tools or manual intervention to set up
249 * those flags correctly.
250 */
251static void wait_for_devices(struct xenbus_driver *xendrv)
252{
253	unsigned long start = jiffies;
254	struct device_driver *drv = xendrv ? &xendrv->driver : NULL;
255	unsigned int seconds_waited = 0;
256
257	if (!ready_to_wait_for_devices || !xen_domain())
258		return;
259
260	while (exists_non_essential_connecting_device(drv))
261		if (wait_loop(start, 30, &seconds_waited))
262			break;
263
264	/* Skips PVKB and PVFB check.*/
265	while (exists_essential_connecting_device(drv))
266		if (wait_loop(start, 270, &seconds_waited))
267			break;
268
269	if (seconds_waited)
270		printk("\n");
271
272	bus_for_each_dev(&xenbus_frontend.bus, NULL, drv,
273			 print_device_status);
274}
275
276int xenbus_register_frontend(struct xenbus_driver *drv)
277{
278	int ret;
279
280	drv->read_otherend_details = read_backend_details;
281
282	ret = xenbus_register_driver_common(drv, &xenbus_frontend);
283	if (ret)
284		return ret;
285
286	/* If this driver is loaded as a module wait for devices to attach. */
287	wait_for_devices(drv);
288
289	return 0;
290}
291EXPORT_SYMBOL_GPL(xenbus_register_frontend);
292
293static DECLARE_WAIT_QUEUE_HEAD(backend_state_wq);
294static int backend_state;
295
296static void xenbus_reset_backend_state_changed(struct xenbus_watch *w,
297					const char **v, unsigned int l)
298{
299	xenbus_scanf(XBT_NIL, v[XS_WATCH_PATH], "", "%i", &backend_state);
300	printk(KERN_DEBUG "XENBUS: backend %s %s\n",
301			v[XS_WATCH_PATH], xenbus_strstate(backend_state));
302	wake_up(&backend_state_wq);
303}
304
305static void xenbus_reset_wait_for_backend(char *be, int expected)
306{
307	long timeout;
308	timeout = wait_event_interruptible_timeout(backend_state_wq,
309			backend_state == expected, 5 * HZ);
310	if (timeout <= 0)
311		printk(KERN_INFO "XENBUS: backend %s timed out.\n", be);
312}
313
314/*
315 * Reset frontend if it is in Connected or Closed state.
316 * Wait for backend to catch up.
317 * State Connected happens during kdump, Closed after kexec.
318 */
319static void xenbus_reset_frontend(char *fe, char *be, int be_state)
320{
321	struct xenbus_watch be_watch;
322
323	printk(KERN_DEBUG "XENBUS: backend %s %s\n",
324			be, xenbus_strstate(be_state));
325
326	memset(&be_watch, 0, sizeof(be_watch));
327	be_watch.node = kasprintf(GFP_NOIO | __GFP_HIGH, "%s/state", be);
328	if (!be_watch.node)
329		return;
330
331	be_watch.callback = xenbus_reset_backend_state_changed;
332	backend_state = XenbusStateUnknown;
333
334	printk(KERN_INFO "XENBUS: triggering reconnect on %s\n", be);
335	register_xenbus_watch(&be_watch);
336
337	/* fall through to forward backend to state XenbusStateInitialising */
338	switch (be_state) {
339	case XenbusStateConnected:
340		xenbus_printf(XBT_NIL, fe, "state", "%d", XenbusStateClosing);
341		xenbus_reset_wait_for_backend(be, XenbusStateClosing);
342
343	case XenbusStateClosing:
344		xenbus_printf(XBT_NIL, fe, "state", "%d", XenbusStateClosed);
345		xenbus_reset_wait_for_backend(be, XenbusStateClosed);
346
347	case XenbusStateClosed:
348		xenbus_printf(XBT_NIL, fe, "state", "%d", XenbusStateInitialising);
349		xenbus_reset_wait_for_backend(be, XenbusStateInitWait);
350	}
351
352	unregister_xenbus_watch(&be_watch);
353	printk(KERN_INFO "XENBUS: reconnect done on %s\n", be);
354	kfree(be_watch.node);
355}
356
357static void xenbus_check_frontend(char *class, char *dev)
358{
359	int be_state, fe_state, err;
360	char *backend, *frontend;
361
362	frontend = kasprintf(GFP_NOIO | __GFP_HIGH, "device/%s/%s", class, dev);
363	if (!frontend)
364		return;
365
366	err = xenbus_scanf(XBT_NIL, frontend, "state", "%i", &fe_state);
367	if (err != 1)
368		goto out;
369
370	switch (fe_state) {
371	case XenbusStateConnected:
372	case XenbusStateClosed:
373		printk(KERN_DEBUG "XENBUS: frontend %s %s\n",
374				frontend, xenbus_strstate(fe_state));
375		backend = xenbus_read(XBT_NIL, frontend, "backend", NULL);
376		if (!backend || IS_ERR(backend))
377			goto out;
378		err = xenbus_scanf(XBT_NIL, backend, "state", "%i", &be_state);
379		if (err == 1)
380			xenbus_reset_frontend(frontend, backend, be_state);
381		kfree(backend);
382		break;
383	default:
384		break;
385	}
386out:
387	kfree(frontend);
388}
389
390static void xenbus_reset_state(void)
391{
392	char **devclass, **dev;
393	int devclass_n, dev_n;
394	int i, j;
395
396	devclass = xenbus_directory(XBT_NIL, "device", "", &devclass_n);
397	if (IS_ERR(devclass))
398		return;
399
400	for (i = 0; i < devclass_n; i++) {
401		dev = xenbus_directory(XBT_NIL, "device", devclass[i], &dev_n);
402		if (IS_ERR(dev))
403			continue;
404		for (j = 0; j < dev_n; j++)
405			xenbus_check_frontend(devclass[i], dev[j]);
406		kfree(dev);
407	}
408	kfree(devclass);
409}
410
411static int frontend_probe_and_watch(struct notifier_block *notifier,
412				   unsigned long event,
413				   void *data)
414{
415	/* reset devices in Connected or Closed state */
416	if (xen_hvm_domain())
417		xenbus_reset_state();
418	/* Enumerate devices in xenstore and watch for changes. */
419	xenbus_probe_devices(&xenbus_frontend);
420	register_xenbus_watch(&fe_watch);
421
422	return NOTIFY_DONE;
423}
424
425
426static int __init xenbus_probe_frontend_init(void)
427{
428	static struct notifier_block xenstore_notifier = {
429		.notifier_call = frontend_probe_and_watch
430	};
431	int err;
432
433	DPRINTK("");
434
435	/* Register ourselves with the kernel bus subsystem */
436	err = bus_register(&xenbus_frontend.bus);
437	if (err)
438		return err;
439
440	register_xenstore_notifier(&xenstore_notifier);
441
442	return 0;
443}
444subsys_initcall(xenbus_probe_frontend_init);
445
446#ifndef MODULE
447static int __init boot_wait_for_devices(void)
448{
449	if (xen_hvm_domain() && !xen_platform_pci_unplug)
450		return -ENODEV;
451
452	ready_to_wait_for_devices = 1;
453	wait_for_devices(NULL);
454	return 0;
455}
456
457late_initcall(boot_wait_for_devices);
458#endif
459
460MODULE_LICENSE("GPL");
461