drivers/xen/manage.c

   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/page.h>
  23 #include <xen/xen-ops.h>
  24
  25 #include <asm/xen/hypercall.h>
  26 #include <asm/xen/hypervisor.h>
  27
  28 enum 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. */
  40 static enum shutdown_state shutting_down = SHUTDOWN_INVALID;
  41
  42 struct suspend_info {
  43         int cancelled;
  44 };
  45
  46 static RAW_NOTIFIER_HEAD(xen_resume_notifier);
  47
  48 void xen_resume_notifier_register(struct notifier_block *nb)
  49 {
  50         raw_notifier_chain_register(&xen_resume_notifier, nb);
  51 }
  52 EXPORT_SYMBOL_GPL(xen_resume_notifier_register);
  53
  54 void xen_resume_notifier_unregister(struct notifier_block *nb)
  55 {
  56         raw_notifier_chain_unregister(&xen_resume_notifier, nb);
  57 }
  58 EXPORT_SYMBOL_GPL(xen_resume_notifier_unregister);
  59
  60 #ifdef CONFIG_HIBERNATE_CALLBACKS
  61 static 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_manage_runstate_time(-1);
  76         xen_arch_pre_suspend();
  77
  78         si->cancelled = HYPERVISOR_suspend(xen_pv_domain()
  79                                            ? virt_to_gfn(xen_start_info)
  80                                            : 0);
  81
  82         xen_arch_post_suspend(si->cancelled);
  83         xen_manage_runstate_time(si->cancelled ? 1 : 0);
  84         gnttab_resume();
  85
  86         if (!si->cancelled) {
  87                 xen_irq_resume();
  88                 xen_timer_resume();
  89         }
  90
  91         syscore_resume();
  92
  93         return 0;
  94 }
  95
  96 static void do_suspend(void)
  97 {
  98         int err;
  99         struct suspend_info si;
 100
 101         shutting_down = SHUTDOWN_SUSPEND;
 102
 103         err = freeze_processes();
 104         if (err) {
 105                 pr_err("%s: freeze processes failed %d\n", __func__, err);
 106                 goto out;
 107         }
 108
 109         err = freeze_kernel_threads();
 110         if (err) {
 111                 pr_err("%s: freeze kernel threads failed %d\n", __func__, err);
 112                 goto out_thaw;
 113         }
 114
 115         err = dpm_suspend_start(PMSG_FREEZE);
 116         if (err) {
 117                 pr_err("%s: dpm_suspend_start %d\n", __func__, err);
 118                 goto out_thaw;
 119         }
 120
 121         printk(KERN_DEBUG "suspending xenstore...\n");
 122         xs_suspend();
 123
 124         err = dpm_suspend_end(PMSG_FREEZE);
 125         if (err) {
 126                 pr_err("dpm_suspend_end failed: %d\n", err);
 127                 si.cancelled = 0;
 128                 goto out_resume;
 129         }
 130
 131         xen_arch_suspend();
 132
 133         si.cancelled = 1;
 134
 135         err = stop_machine(xen_suspend, &si, cpumask_of(0));
 136
 137         /* Resume console as early as possible. */
 138         if (!si.cancelled)
 139                 xen_console_resume();
 140
 141         raw_notifier_call_chain(&xen_resume_notifier, 0, NULL);
 142
 143         dpm_resume_start(si.cancelled ? PMSG_THAW : PMSG_RESTORE);
 144
 145         if (err) {
 146                 pr_err("failed to start xen_suspend: %d\n", err);
 147                 si.cancelled = 1;
 148         }
 149
 150         xen_arch_resume();
 151
 152 out_resume:
 153         if (!si.cancelled)
 154                 xs_resume();
 155         else
 156                 xs_suspend_cancel();
 157
 158         dpm_resume_end(si.cancelled ? PMSG_THAW : PMSG_RESTORE);
 159
 160 out_thaw:
 161         thaw_processes();
 162 out:
 163         shutting_down = SHUTDOWN_INVALID;
 164 }
 165 #endif  /* CONFIG_HIBERNATE_CALLBACKS */
 166
 167 struct shutdown_handler {
 168 #define SHUTDOWN_CMD_SIZE 11
 169         const char command[SHUTDOWN_CMD_SIZE];
 170         bool flag;
 171         void (*cb)(void);
 172 };
 173
 174 static int poweroff_nb(struct notifier_block *cb, unsigned long code, void *unused)
 175 {
 176         switch (code) {
 177         case SYS_DOWN:
 178         case SYS_HALT:
 179         case SYS_POWER_OFF:
 180                 shutting_down = SHUTDOWN_POWEROFF;
 181         default:
 182                 break;
 183         }
 184         return NOTIFY_DONE;
 185 }
 186 static void do_poweroff(void)
 187 {
 188         switch (system_state) {
 189         case SYSTEM_BOOTING:
 190         case SYSTEM_SCHEDULING:
 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
 203 static void do_reboot(void)
 204 {
 205         shutting_down = SHUTDOWN_POWEROFF; /* ? */
 206         ctrl_alt_del();
 207 }
 208
 209 static struct shutdown_handler shutdown_handlers[] = {
 210         { "poweroff",   true,   do_poweroff },
 211         { "halt",       false,  do_poweroff },
 212         { "reboot",     true,   do_reboot   },
 213 #ifdef CONFIG_HIBERNATE_CALLBACKS
 214         { "suspend",    true,   do_suspend  },
 215 #endif
 216 };
 217
 218 static void shutdown_handler(struct xenbus_watch *watch,
 219                              const char *path, const char *token)
 220 {
 221         char *str;
 222         struct xenbus_transaction xbt;
 223         int err;
 224         int idx;
 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 (idx = 0; idx < ARRAY_SIZE(shutdown_handlers); idx++) {
 242                 if (strcmp(str, shutdown_handlers[idx].command) == 0)
 243                         break;
 244         }
 245
 246         /* Only acknowledge commands which we are prepared to handle. */
 247         if (idx < ARRAY_SIZE(shutdown_handlers))
 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 (idx < ARRAY_SIZE(shutdown_handlers)) {
 257                 shutdown_handlers[idx].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
 267 static void sysrq_handler(struct xenbus_watch *watch, const char *path,
 268                           const char *token)
 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         err = xenbus_scanf(xbt, "control", "sysrq", "%c", &sysrq_key);
 279         if (err < 0) {
 280                 /*
 281                  * The Xenstore watch fires directly after registering it and
 282                  * after a suspend/resume cycle. So ENOENT is no error but
 283                  * might happen in those cases. ERANGE is observed when we get
 284                  * an empty value (''), this happens when we acknowledge the
 285                  * request by writing '\0' below.
 286                  */
 287                 if (err != -ENOENT && err != -ERANGE)
 288                         pr_err("Error %d reading sysrq code in control/sysrq\n",
 289                                err);
 290                 xenbus_transaction_end(xbt, 1);
 291                 return;
 292         }
 293
 294         if (sysrq_key != '\0') {
 295                 err = xenbus_printf(xbt, "control", "sysrq", "%c", '\0');
 296                 if (err) {
 297                         pr_err("%s: Error %d writing sysrq in control/sysrq\n",
 298                                __func__, err);
 299                         xenbus_transaction_end(xbt, 1);
 300                         return;
 301                 }
 302         }
 303
 304         err = xenbus_transaction_end(xbt, 0);
 305         if (err == -EAGAIN)
 306                 goto again;
 307
 308         if (sysrq_key != '\0')
 309                 handle_sysrq(sysrq_key);
 310 }
 311
 312 static struct xenbus_watch sysrq_watch = {
 313         .node = "control/sysrq",
 314         .callback = sysrq_handler
 315 };
 316 #endif
 317
 318 static struct xenbus_watch shutdown_watch = {
 319         .node = "control/shutdown",
 320         .callback = shutdown_handler
 321 };
 322
 323 static struct notifier_block xen_reboot_nb = {
 324         .notifier_call = poweroff_nb,
 325 };
 326
 327 static int setup_shutdown_watcher(void)
 328 {
 329         int err;
 330         int idx;
 331 #define FEATURE_PATH_SIZE (SHUTDOWN_CMD_SIZE + sizeof("feature-"))
 332         char node[FEATURE_PATH_SIZE];
 333
 334         err = register_xenbus_watch(&shutdown_watch);
 335         if (err) {
 336                 pr_err("Failed to set shutdown watcher\n");
 337                 return err;
 338         }
 339
 340
 341 #ifdef CONFIG_MAGIC_SYSRQ
 342         err = register_xenbus_watch(&sysrq_watch);
 343         if (err) {
 344                 pr_err("Failed to set sysrq watcher\n");
 345                 return err;
 346         }
 347 #endif
 348
 349         for (idx = 0; idx < ARRAY_SIZE(shutdown_handlers); idx++) {
 350                 if (!shutdown_handlers[idx].flag)
 351                         continue;
 352                 snprintf(node, FEATURE_PATH_SIZE, "feature-%s",
 353                          shutdown_handlers[idx].command);
 354                 err = xenbus_printf(XBT_NIL, "control", node, "%u", 1);
 355                 if (err) {
 356                         pr_err("%s: Error %d writing %s\n", __func__,
 357                                 err, node);
 358                         return err;
 359                 }
 360         }
 361
 362         return 0;
 363 }
 364
 365 static int shutdown_event(struct notifier_block *notifier,
 366                           unsigned long event,
 367                           void *data)
 368 {
 369         setup_shutdown_watcher();
 370         return NOTIFY_DONE;
 371 }
 372
 373 int xen_setup_shutdown_event(void)
 374 {
 375         static struct notifier_block xenstore_notifier = {
 376                 .notifier_call = shutdown_event
 377         };
 378
 379         if (!xen_domain())
 380                 return -ENODEV;
 381         register_xenstore_notifier(&xenstore_notifier);
 382         register_reboot_notifier(&xen_reboot_nb);
 383
 384         return 0;
 385 }
 386 EXPORT_SYMBOL_GPL(xen_setup_shutdown_event);
 387
 388 subsys_initcall(xen_setup_shutdown_event);