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 xen_arch_resume();
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 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 break;
183 default:
184 break;
185 }
186 return NOTIFY_DONE;
187 }
do_poweroff(void)188 static void do_poweroff(void)
189 {
190 switch (system_state) {
191 case SYSTEM_BOOTING:
192 case SYSTEM_SCHEDULING:
193 orderly_poweroff(true);
194 break;
195 case SYSTEM_RUNNING:
196 orderly_poweroff(false);
197 break;
198 default:
199 /* Don't do it when we are halting/rebooting. */
200 pr_info("Ignoring Xen toolstack shutdown.\n");
201 break;
202 }
203 }
204
do_reboot(void)205 static void do_reboot(void)
206 {
207 shutting_down = SHUTDOWN_POWEROFF; /* ? */
208 orderly_reboot();
209 }
210
211 static struct shutdown_handler shutdown_handlers[] = {
212 { "poweroff", true, do_poweroff },
213 { "halt", false, do_poweroff },
214 { "reboot", true, do_reboot },
215 #ifdef CONFIG_HIBERNATE_CALLBACKS
216 { "suspend", true, do_suspend },
217 #endif
218 };
219
shutdown_handler(struct xenbus_watch * watch,const char * path,const char * token)220 static void shutdown_handler(struct xenbus_watch *watch,
221 const char *path, const char *token)
222 {
223 char *str;
224 struct xenbus_transaction xbt;
225 int err;
226 int idx;
227
228 if (shutting_down != SHUTDOWN_INVALID)
229 return;
230
231 again:
232 err = xenbus_transaction_start(&xbt);
233 if (err)
234 return;
235
236 str = (char *)xenbus_read(xbt, "control", "shutdown", NULL);
237 /* Ignore read errors and empty reads. */
238 if (XENBUS_IS_ERR_READ(str)) {
239 xenbus_transaction_end(xbt, 1);
240 return;
241 }
242
243 for (idx = 0; idx < ARRAY_SIZE(shutdown_handlers); idx++) {
244 if (strcmp(str, shutdown_handlers[idx].command) == 0)
245 break;
246 }
247
248 /* Only acknowledge commands which we are prepared to handle. */
249 if (idx < ARRAY_SIZE(shutdown_handlers))
250 xenbus_write(xbt, "control", "shutdown", "");
251
252 err = xenbus_transaction_end(xbt, 0);
253 if (err == -EAGAIN) {
254 kfree(str);
255 goto again;
256 }
257
258 if (idx < ARRAY_SIZE(shutdown_handlers)) {
259 shutdown_handlers[idx].cb();
260 } else {
261 pr_info("Ignoring shutdown request: %s\n", str);
262 shutting_down = SHUTDOWN_INVALID;
263 }
264
265 kfree(str);
266 }
267
268 #ifdef CONFIG_MAGIC_SYSRQ
sysrq_handler(struct xenbus_watch * watch,const char * path,const char * token)269 static void sysrq_handler(struct xenbus_watch *watch, const char *path,
270 const char *token)
271 {
272 char sysrq_key = '\0';
273 struct xenbus_transaction xbt;
274 int err;
275
276 again:
277 err = xenbus_transaction_start(&xbt);
278 if (err)
279 return;
280 err = xenbus_scanf(xbt, "control", "sysrq", "%c", &sysrq_key);
281 if (err < 0) {
282 /*
283 * The Xenstore watch fires directly after registering it and
284 * after a suspend/resume cycle. So ENOENT is no error but
285 * might happen in those cases. ERANGE is observed when we get
286 * an empty value (''), this happens when we acknowledge the
287 * request by writing '\0' below.
288 */
289 if (err != -ENOENT && err != -ERANGE)
290 pr_err("Error %d reading sysrq code in control/sysrq\n",
291 err);
292 xenbus_transaction_end(xbt, 1);
293 return;
294 }
295
296 if (sysrq_key != '\0') {
297 err = xenbus_printf(xbt, "control", "sysrq", "%c", '\0');
298 if (err) {
299 pr_err("%s: Error %d writing sysrq in control/sysrq\n",
300 __func__, err);
301 xenbus_transaction_end(xbt, 1);
302 return;
303 }
304 }
305
306 err = xenbus_transaction_end(xbt, 0);
307 if (err == -EAGAIN)
308 goto again;
309
310 if (sysrq_key != '\0')
311 handle_sysrq(sysrq_key);
312 }
313
314 static struct xenbus_watch sysrq_watch = {
315 .node = "control/sysrq",
316 .callback = sysrq_handler
317 };
318 #endif
319
320 static struct xenbus_watch shutdown_watch = {
321 .node = "control/shutdown",
322 .callback = shutdown_handler
323 };
324
325 static struct notifier_block xen_reboot_nb = {
326 .notifier_call = poweroff_nb,
327 };
328
setup_shutdown_watcher(void)329 static int setup_shutdown_watcher(void)
330 {
331 int err;
332 int idx;
333 #define FEATURE_PATH_SIZE (SHUTDOWN_CMD_SIZE + sizeof("feature-"))
334 char node[FEATURE_PATH_SIZE];
335
336 err = register_xenbus_watch(&shutdown_watch);
337 if (err) {
338 pr_err("Failed to set shutdown watcher\n");
339 return err;
340 }
341
342
343 #ifdef CONFIG_MAGIC_SYSRQ
344 err = register_xenbus_watch(&sysrq_watch);
345 if (err) {
346 pr_err("Failed to set sysrq watcher\n");
347 return err;
348 }
349 #endif
350
351 for (idx = 0; idx < ARRAY_SIZE(shutdown_handlers); idx++) {
352 if (!shutdown_handlers[idx].flag)
353 continue;
354 snprintf(node, FEATURE_PATH_SIZE, "feature-%s",
355 shutdown_handlers[idx].command);
356 err = xenbus_printf(XBT_NIL, "control", node, "%u", 1);
357 if (err) {
358 pr_err("%s: Error %d writing %s\n", __func__,
359 err, node);
360 return err;
361 }
362 }
363
364 return 0;
365 }
366
shutdown_event(struct notifier_block * notifier,unsigned long event,void * data)367 static int shutdown_event(struct notifier_block *notifier,
368 unsigned long event,
369 void *data)
370 {
371 setup_shutdown_watcher();
372 return NOTIFY_DONE;
373 }
374
xen_setup_shutdown_event(void)375 int xen_setup_shutdown_event(void)
376 {
377 static struct notifier_block xenstore_notifier = {
378 .notifier_call = shutdown_event
379 };
380
381 if (!xen_domain())
382 return -ENODEV;
383 register_xenstore_notifier(&xenstore_notifier);
384 register_reboot_notifier(&xen_reboot_nb);
385
386 return 0;
387 }
388 EXPORT_SYMBOL_GPL(xen_setup_shutdown_event);
389
390 subsys_initcall(xen_setup_shutdown_event);
391