1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Handle extern requests for shutdown, reboot and sysrq
4 */
5
6 #define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt
7
8 #include <linux/kernel.h>
9 #include <linux/err.h>
10 #include <linux/slab.h>
11 #include <linux/reboot.h>
12 #include <linux/sysrq.h>
13 #include <linux/stop_machine.h>
14 #include <linux/freezer.h>
15 #include <linux/syscore_ops.h>
16 #include <linux/export.h>
17
18 #include <xen/xen.h>
19 #include <xen/xenbus.h>
20 #include <xen/grant_table.h>
21 #include <xen/events.h>
22 #include <xen/hvc-console.h>
23 #include <xen/page.h>
24 #include <xen/xen-ops.h>
25
26 #include <asm/xen/hypercall.h>
27 #include <asm/xen/hypervisor.h>
28
29 enum shutdown_state {
30 SHUTDOWN_INVALID = -1,
31 SHUTDOWN_POWEROFF = 0,
32 SHUTDOWN_SUSPEND = 2,
33 /* Code 3 is SHUTDOWN_CRASH, which we don't use because the domain can only
34 report a crash, not be instructed to crash!
35 HALT is the same as POWEROFF, as far as we're concerned. The tools use
36 the distinction when we return the reason code to them. */
37 SHUTDOWN_HALT = 4,
38 };
39
40 /* Ignore multiple shutdown requests. */
41 static enum shutdown_state shutting_down = SHUTDOWN_INVALID;
42
43 struct suspend_info {
44 int cancelled;
45 };
46
47 static RAW_NOTIFIER_HEAD(xen_resume_notifier);
48
xen_resume_notifier_register(struct notifier_block * nb)49 void xen_resume_notifier_register(struct notifier_block *nb)
50 {
51 raw_notifier_chain_register(&xen_resume_notifier, nb);
52 }
53 EXPORT_SYMBOL_GPL(xen_resume_notifier_register);
54
xen_resume_notifier_unregister(struct notifier_block * nb)55 void xen_resume_notifier_unregister(struct notifier_block *nb)
56 {
57 raw_notifier_chain_unregister(&xen_resume_notifier, nb);
58 }
59 EXPORT_SYMBOL_GPL(xen_resume_notifier_unregister);
60
61 #ifdef CONFIG_HIBERNATE_CALLBACKS
xen_suspend(void * data)62 static int xen_suspend(void *data)
63 {
64 struct suspend_info *si = data;
65 int err;
66
67 BUG_ON(!irqs_disabled());
68
69 err = syscore_suspend();
70 if (err) {
71 pr_err("%s: system core suspend failed: %d\n", __func__, err);
72 return err;
73 }
74
75 gnttab_suspend();
76 xen_manage_runstate_time(-1);
77 xen_arch_pre_suspend();
78
79 si->cancelled = HYPERVISOR_suspend(xen_pv_domain()
80 ? virt_to_gfn(xen_start_info)
81 : 0);
82
83 xen_arch_post_suspend(si->cancelled);
84 xen_manage_runstate_time(si->cancelled ? 1 : 0);
85 gnttab_resume();
86
87 if (!si->cancelled) {
88 xen_irq_resume();
89 xen_timer_resume();
90 }
91
92 syscore_resume();
93
94 return 0;
95 }
96
do_suspend(void)97 static void do_suspend(void)
98 {
99 int err;
100 struct suspend_info si;
101
102 shutting_down = SHUTDOWN_SUSPEND;
103
104 err = freeze_processes();
105 if (err) {
106 pr_err("%s: freeze processes failed %d\n", __func__, err);
107 goto out;
108 }
109
110 err = freeze_kernel_threads();
111 if (err) {
112 pr_err("%s: freeze kernel threads failed %d\n", __func__, err);
113 goto out_thaw;
114 }
115
116 err = dpm_suspend_start(PMSG_FREEZE);
117 if (err) {
118 pr_err("%s: dpm_suspend_start %d\n", __func__, err);
119 goto out_thaw;
120 }
121
122 printk(KERN_DEBUG "suspending xenstore...\n");
123 xs_suspend();
124
125 err = dpm_suspend_end(PMSG_FREEZE);
126 if (err) {
127 pr_err("dpm_suspend_end failed: %d\n", err);
128 si.cancelled = 0;
129 goto out_resume;
130 }
131
132 xen_arch_suspend();
133
134 si.cancelled = 1;
135
136 err = stop_machine(xen_suspend, &si, cpumask_of(0));
137
138 /* Resume console as early as possible. */
139 if (!si.cancelled)
140 xen_console_resume();
141
142 raw_notifier_call_chain(&xen_resume_notifier, 0, NULL);
143
144 dpm_resume_start(si.cancelled ? PMSG_THAW : PMSG_RESTORE);
145
146 if (err) {
147 pr_err("failed to start xen_suspend: %d\n", err);
148 si.cancelled = 1;
149 }
150
151 xen_arch_resume();
152
153 out_resume:
154 if (!si.cancelled)
155 xs_resume();
156 else
157 xs_suspend_cancel();
158
159 dpm_resume_end(si.cancelled ? PMSG_THAW : PMSG_RESTORE);
160
161 out_thaw:
162 thaw_processes();
163 out:
164 shutting_down = SHUTDOWN_INVALID;
165 }
166 #endif /* CONFIG_HIBERNATE_CALLBACKS */
167
168 struct shutdown_handler {
169 #define SHUTDOWN_CMD_SIZE 11
170 const char command[SHUTDOWN_CMD_SIZE];
171 bool flag;
172 void (*cb)(void);
173 };
174
poweroff_nb(struct notifier_block * cb,unsigned long code,void * unused)175 static 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 }
do_poweroff(void)187 static void do_poweroff(void)
188 {
189 switch (system_state) {
190 case SYSTEM_BOOTING:
191 case SYSTEM_SCHEDULING:
192 orderly_poweroff(true);
193 break;
194 case SYSTEM_RUNNING:
195 orderly_poweroff(false);
196 break;
197 default:
198 /* Don't do it when we are halting/rebooting. */
199 pr_info("Ignoring Xen toolstack shutdown.\n");
200 break;
201 }
202 }
203
do_reboot(void)204 static void do_reboot(void)
205 {
206 shutting_down = SHUTDOWN_POWEROFF; /* ? */
207 ctrl_alt_del();
208 }
209
210 static struct shutdown_handler shutdown_handlers[] = {
211 { "poweroff", true, do_poweroff },
212 { "halt", false, do_poweroff },
213 { "reboot", true, do_reboot },
214 #ifdef CONFIG_HIBERNATE_CALLBACKS
215 { "suspend", true, do_suspend },
216 #endif
217 };
218
shutdown_handler(struct xenbus_watch * watch,const char * path,const char * token)219 static void shutdown_handler(struct xenbus_watch *watch,
220 const char *path, const char *token)
221 {
222 char *str;
223 struct xenbus_transaction xbt;
224 int err;
225 int idx;
226
227 if (shutting_down != SHUTDOWN_INVALID)
228 return;
229
230 again:
231 err = xenbus_transaction_start(&xbt);
232 if (err)
233 return;
234
235 str = (char *)xenbus_read(xbt, "control", "shutdown", NULL);
236 /* Ignore read errors and empty reads. */
237 if (XENBUS_IS_ERR_READ(str)) {
238 xenbus_transaction_end(xbt, 1);
239 return;
240 }
241
242 for (idx = 0; idx < ARRAY_SIZE(shutdown_handlers); idx++) {
243 if (strcmp(str, shutdown_handlers[idx].command) == 0)
244 break;
245 }
246
247 /* Only acknowledge commands which we are prepared to handle. */
248 if (idx < ARRAY_SIZE(shutdown_handlers))
249 xenbus_write(xbt, "control", "shutdown", "");
250
251 err = xenbus_transaction_end(xbt, 0);
252 if (err == -EAGAIN) {
253 kfree(str);
254 goto again;
255 }
256
257 if (idx < ARRAY_SIZE(shutdown_handlers)) {
258 shutdown_handlers[idx].cb();
259 } else {
260 pr_info("Ignoring shutdown request: %s\n", str);
261 shutting_down = SHUTDOWN_INVALID;
262 }
263
264 kfree(str);
265 }
266
267 #ifdef CONFIG_MAGIC_SYSRQ
sysrq_handler(struct xenbus_watch * watch,const char * path,const char * token)268 static void sysrq_handler(struct xenbus_watch *watch, const char *path,
269 const char *token)
270 {
271 char sysrq_key = '\0';
272 struct xenbus_transaction xbt;
273 int err;
274
275 again:
276 err = xenbus_transaction_start(&xbt);
277 if (err)
278 return;
279 err = xenbus_scanf(xbt, "control", "sysrq", "%c", &sysrq_key);
280 if (err < 0) {
281 /*
282 * The Xenstore watch fires directly after registering it and
283 * after a suspend/resume cycle. So ENOENT is no error but
284 * might happen in those cases. ERANGE is observed when we get
285 * an empty value (''), this happens when we acknowledge the
286 * request by writing '\0' below.
287 */
288 if (err != -ENOENT && err != -ERANGE)
289 pr_err("Error %d reading sysrq code in control/sysrq\n",
290 err);
291 xenbus_transaction_end(xbt, 1);
292 return;
293 }
294
295 if (sysrq_key != '\0') {
296 err = xenbus_printf(xbt, "control", "sysrq", "%c", '\0');
297 if (err) {
298 pr_err("%s: Error %d writing sysrq in control/sysrq\n",
299 __func__, err);
300 xenbus_transaction_end(xbt, 1);
301 return;
302 }
303 }
304
305 err = xenbus_transaction_end(xbt, 0);
306 if (err == -EAGAIN)
307 goto again;
308
309 if (sysrq_key != '\0')
310 handle_sysrq(sysrq_key);
311 }
312
313 static struct xenbus_watch sysrq_watch = {
314 .node = "control/sysrq",
315 .callback = sysrq_handler
316 };
317 #endif
318
319 static struct xenbus_watch shutdown_watch = {
320 .node = "control/shutdown",
321 .callback = shutdown_handler
322 };
323
324 static struct notifier_block xen_reboot_nb = {
325 .notifier_call = poweroff_nb,
326 };
327
setup_shutdown_watcher(void)328 static int setup_shutdown_watcher(void)
329 {
330 int err;
331 int idx;
332 #define FEATURE_PATH_SIZE (SHUTDOWN_CMD_SIZE + sizeof("feature-"))
333 char node[FEATURE_PATH_SIZE];
334
335 err = register_xenbus_watch(&shutdown_watch);
336 if (err) {
337 pr_err("Failed to set shutdown watcher\n");
338 return err;
339 }
340
341
342 #ifdef CONFIG_MAGIC_SYSRQ
343 err = register_xenbus_watch(&sysrq_watch);
344 if (err) {
345 pr_err("Failed to set sysrq watcher\n");
346 return err;
347 }
348 #endif
349
350 for (idx = 0; idx < ARRAY_SIZE(shutdown_handlers); idx++) {
351 if (!shutdown_handlers[idx].flag)
352 continue;
353 snprintf(node, FEATURE_PATH_SIZE, "feature-%s",
354 shutdown_handlers[idx].command);
355 err = xenbus_printf(XBT_NIL, "control", node, "%u", 1);
356 if (err) {
357 pr_err("%s: Error %d writing %s\n", __func__,
358 err, node);
359 return err;
360 }
361 }
362
363 return 0;
364 }
365
shutdown_event(struct notifier_block * notifier,unsigned long event,void * data)366 static int shutdown_event(struct notifier_block *notifier,
367 unsigned long event,
368 void *data)
369 {
370 setup_shutdown_watcher();
371 return NOTIFY_DONE;
372 }
373
xen_setup_shutdown_event(void)374 int xen_setup_shutdown_event(void)
375 {
376 static struct notifier_block xenstore_notifier = {
377 .notifier_call = shutdown_event
378 };
379
380 if (!xen_domain())
381 return -ENODEV;
382 register_xenstore_notifier(&xenstore_notifier);
383 register_reboot_notifier(&xen_reboot_nb);
384
385 return 0;
386 }
387 EXPORT_SYMBOL_GPL(xen_setup_shutdown_event);
388
389 subsys_initcall(xen_setup_shutdown_event);
390
