1/*
2 * Handle extern requests for shutdown, reboot and sysrq
3 */
4
5#define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt
6
7#include <linux/kernel.h>
8#include <linux/err.h>
9#include <linux/slab.h>
10#include <linux/reboot.h>
11#include <linux/sysrq.h>
12#include <linux/stop_machine.h>
13#include <linux/freezer.h>
14#include <linux/syscore_ops.h>
15#include <linux/export.h>
16
17#include <xen/xen.h>
18#include <xen/xenbus.h>
19#include <xen/grant_table.h>
20#include <xen/events.h>
21#include <xen/hvc-console.h>
22#include <xen/xen-ops.h>
23
24#include <asm/xen/hypercall.h>
25#include <asm/xen/page.h>
26#include <asm/xen/hypervisor.h>
27
28enum shutdown_state {
29	SHUTDOWN_INVALID = -1,
30	SHUTDOWN_POWEROFF = 0,
31	SHUTDOWN_SUSPEND = 2,
32	/* Code 3 is SHUTDOWN_CRASH, which we don't use because the domain can only
33	   report a crash, not be instructed to crash!
34	   HALT is the same as POWEROFF, as far as we're concerned.  The tools use
35	   the distinction when we return the reason code to them.  */
36	 SHUTDOWN_HALT = 4,
37};
38
39/* Ignore multiple shutdown requests. */
40static enum shutdown_state shutting_down = SHUTDOWN_INVALID;
41
42struct suspend_info {
43	int cancelled;
44};
45
46static RAW_NOTIFIER_HEAD(xen_resume_notifier);
47
48void xen_resume_notifier_register(struct notifier_block *nb)
49{
50	raw_notifier_chain_register(&xen_resume_notifier, nb);
51}
52EXPORT_SYMBOL_GPL(xen_resume_notifier_register);
53
54void xen_resume_notifier_unregister(struct notifier_block *nb)
55{
56	raw_notifier_chain_unregister(&xen_resume_notifier, nb);
57}
58EXPORT_SYMBOL_GPL(xen_resume_notifier_unregister);
59
60#ifdef CONFIG_HIBERNATE_CALLBACKS
61static int xen_suspend(void *data)
62{
63	struct suspend_info *si = data;
64	int err;
65
66	BUG_ON(!irqs_disabled());
67
68	err = syscore_suspend();
69	if (err) {
70		pr_err("%s: system core suspend failed: %d\n", __func__, err);
71		return err;
72	}
73
74	gnttab_suspend();
75	xen_arch_pre_suspend();
76
77	/*
78	 * This hypercall returns 1 if suspend was cancelled
79	 * or the domain was merely checkpointed, and 0 if it
80	 * is resuming in a new domain.
81	 */
82	si->cancelled = HYPERVISOR_suspend(xen_pv_domain()
83                                           ? virt_to_mfn(xen_start_info)
84                                           : 0);
85
86	xen_arch_post_suspend(si->cancelled);
87	gnttab_resume();
88
89	if (!si->cancelled) {
90		xen_irq_resume();
91		xen_timer_resume();
92	}
93
94	syscore_resume();
95
96	return 0;
97}
98
99static void do_suspend(void)
100{
101	int err;
102	struct suspend_info si;
103
104	shutting_down = SHUTDOWN_SUSPEND;
105
106	err = freeze_processes();
107	if (err) {
108		pr_err("%s: freeze processes failed %d\n", __func__, err);
109		goto out;
110	}
111
112	err = freeze_kernel_threads();
113	if (err) {
114		pr_err("%s: freeze kernel threads failed %d\n", __func__, err);
115		goto out_thaw;
116	}
117
118	err = dpm_suspend_start(PMSG_FREEZE);
119	if (err) {
120		pr_err("%s: dpm_suspend_start %d\n", __func__, err);
121		goto out_thaw;
122	}
123
124	printk(KERN_DEBUG "suspending xenstore...\n");
125	xs_suspend();
126
127	err = dpm_suspend_end(PMSG_FREEZE);
128	if (err) {
129		pr_err("dpm_suspend_end failed: %d\n", err);
130		si.cancelled = 0;
131		goto out_resume;
132	}
133
134	xen_arch_suspend();
135
136	si.cancelled = 1;
137
138	err = stop_machine(xen_suspend, &si, cpumask_of(0));
139
140	/* Resume console as early as possible. */
141	if (!si.cancelled)
142		xen_console_resume();
143
144	raw_notifier_call_chain(&xen_resume_notifier, 0, NULL);
145
146	dpm_resume_start(si.cancelled ? PMSG_THAW : PMSG_RESTORE);
147
148	if (err) {
149		pr_err("failed to start xen_suspend: %d\n", err);
150		si.cancelled = 1;
151	}
152
153	xen_arch_resume();
154
155out_resume:
156	if (!si.cancelled)
157		xs_resume();
158	else
159		xs_suspend_cancel();
160
161	dpm_resume_end(si.cancelled ? PMSG_THAW : PMSG_RESTORE);
162
163out_thaw:
164	thaw_processes();
165out:
166	shutting_down = SHUTDOWN_INVALID;
167}
168#endif	/* CONFIG_HIBERNATE_CALLBACKS */
169
170struct shutdown_handler {
171	const char *command;
172	void (*cb)(void);
173};
174
175static int poweroff_nb(struct notifier_block *cb, unsigned long code, void *unused)
176{
177	switch (code) {
178	case SYS_DOWN:
179	case SYS_HALT:
180	case SYS_POWER_OFF:
181		shutting_down = SHUTDOWN_POWEROFF;
182	default:
183		break;
184	}
185	return NOTIFY_DONE;
186}
187static void do_poweroff(void)
188{
189	switch (system_state) {
190	case SYSTEM_BOOTING:
191		orderly_poweroff(true);
192		break;
193	case SYSTEM_RUNNING:
194		orderly_poweroff(false);
195		break;
196	default:
197		/* Don't do it when we are halting/rebooting. */
198		pr_info("Ignoring Xen toolstack shutdown.\n");
199		break;
200	}
201}
202
203static void do_reboot(void)
204{
205	shutting_down = SHUTDOWN_POWEROFF; /* ? */
206	ctrl_alt_del();
207}
208
209static void shutdown_handler(struct xenbus_watch *watch,
210			     const char **vec, unsigned int len)
211{
212	char *str;
213	struct xenbus_transaction xbt;
214	int err;
215	static struct shutdown_handler handlers[] = {
216		{ "poweroff",	do_poweroff },
217		{ "halt",	do_poweroff },
218		{ "reboot",	do_reboot   },
219#ifdef CONFIG_HIBERNATE_CALLBACKS
220		{ "suspend",	do_suspend  },
221#endif
222		{NULL, NULL},
223	};
224	static struct shutdown_handler *handler;
225
226	if (shutting_down != SHUTDOWN_INVALID)
227		return;
228
229 again:
230	err = xenbus_transaction_start(&xbt);
231	if (err)
232		return;
233
234	str = (char *)xenbus_read(xbt, "control", "shutdown", NULL);
235	/* Ignore read errors and empty reads. */
236	if (XENBUS_IS_ERR_READ(str)) {
237		xenbus_transaction_end(xbt, 1);
238		return;
239	}
240
241	for (handler = &handlers[0]; handler->command; handler++) {
242		if (strcmp(str, handler->command) == 0)
243			break;
244	}
245
246	/* Only acknowledge commands which we are prepared to handle. */
247	if (handler->cb)
248		xenbus_write(xbt, "control", "shutdown", "");
249
250	err = xenbus_transaction_end(xbt, 0);
251	if (err == -EAGAIN) {
252		kfree(str);
253		goto again;
254	}
255
256	if (handler->cb) {
257		handler->cb();
258	} else {
259		pr_info("Ignoring shutdown request: %s\n", str);
260		shutting_down = SHUTDOWN_INVALID;
261	}
262
263	kfree(str);
264}
265
266#ifdef CONFIG_MAGIC_SYSRQ
267static void sysrq_handler(struct xenbus_watch *watch, const char **vec,
268			  unsigned int len)
269{
270	char sysrq_key = '\0';
271	struct xenbus_transaction xbt;
272	int err;
273
274 again:
275	err = xenbus_transaction_start(&xbt);
276	if (err)
277		return;
278	if (!xenbus_scanf(xbt, "control", "sysrq", "%c", &sysrq_key)) {
279		pr_err("Unable to read sysrq code in control/sysrq\n");
280		xenbus_transaction_end(xbt, 1);
281		return;
282	}
283
284	if (sysrq_key != '\0')
285		xenbus_printf(xbt, "control", "sysrq", "%c", '\0');
286
287	err = xenbus_transaction_end(xbt, 0);
288	if (err == -EAGAIN)
289		goto again;
290
291	if (sysrq_key != '\0')
292		handle_sysrq(sysrq_key);
293}
294
295static struct xenbus_watch sysrq_watch = {
296	.node = "control/sysrq",
297	.callback = sysrq_handler
298};
299#endif
300
301static struct xenbus_watch shutdown_watch = {
302	.node = "control/shutdown",
303	.callback = shutdown_handler
304};
305
306static struct notifier_block xen_reboot_nb = {
307	.notifier_call = poweroff_nb,
308};
309
310static int setup_shutdown_watcher(void)
311{
312	int err;
313
314	err = register_xenbus_watch(&shutdown_watch);
315	if (err) {
316		pr_err("Failed to set shutdown watcher\n");
317		return err;
318	}
319
320
321#ifdef CONFIG_MAGIC_SYSRQ
322	err = register_xenbus_watch(&sysrq_watch);
323	if (err) {
324		pr_err("Failed to set sysrq watcher\n");
325		return err;
326	}
327#endif
328
329	return 0;
330}
331
332static int shutdown_event(struct notifier_block *notifier,
333			  unsigned long event,
334			  void *data)
335{
336	setup_shutdown_watcher();
337	return NOTIFY_DONE;
338}
339
340int xen_setup_shutdown_event(void)
341{
342	static struct notifier_block xenstore_notifier = {
343		.notifier_call = shutdown_event
344	};
345
346	if (!xen_domain())
347		return -ENODEV;
348	register_xenstore_notifier(&xenstore_notifier);
349	register_reboot_notifier(&xen_reboot_nb);
350
351	return 0;
352}
353EXPORT_SYMBOL_GPL(xen_setup_shutdown_event);
354
355subsys_initcall(xen_setup_shutdown_event);
356