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_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_gfn(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
  99 static 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
 155 out_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
 163 out_thaw:
 164         thaw_processes();
 165 out:
 166         shutting_down = SHUTDOWN_INVALID;
 167 }
 168 #endif  /* CONFIG_HIBERNATE_CALLBACKS */
 169
 170 struct shutdown_handler {
 171 #define SHUTDOWN_CMD_SIZE 11
 172         const char command[SHUTDOWN_CMD_SIZE];
 173         bool flag;
 174         void (*cb)(void);
 175 };
 176
 177 static int poweroff_nb(struct notifier_block *cb, unsigned long code, void *unused)
 178 {
 179         switch (code) {
 180         case SYS_DOWN:
 181         case SYS_HALT:
 182         case SYS_POWER_OFF:
 183                 shutting_down = SHUTDOWN_POWEROFF;
 184         default:
 185                 break;
 186         }
 187         return NOTIFY_DONE;
 188 }
 189 static void do_poweroff(void)
 190 {
 191         switch (system_state) {
 192         case SYSTEM_BOOTING:
 193         case SYSTEM_SCHEDULING:
 194                 orderly_poweroff(true);
 195                 break;
 196         case SYSTEM_RUNNING:
 197                 orderly_poweroff(false);
 198                 break;
 199         default:
 200                 /* Don't do it when we are halting/rebooting. */
 201                 pr_info("Ignoring Xen toolstack shutdown.\n");
 202                 break;
 203         }
 204 }
 205
 206 static void do_reboot(void)
 207 {
 208         shutting_down = SHUTDOWN_POWEROFF; /* ? */
 209         ctrl_alt_del();
 210 }
 211
 212 static struct shutdown_handler shutdown_handlers[] = {
 213         { "poweroff",   true,   do_poweroff },
 214         { "halt",       false,  do_poweroff },
 215         { "reboot",     true,   do_reboot   },
 216 #ifdef CONFIG_HIBERNATE_CALLBACKS
 217         { "suspend",    true,   do_suspend  },
 218 #endif
 219 };
 220
 221 static void shutdown_handler(struct xenbus_watch *watch,
 222                              const char *path, const char *token)
 223 {
 224         char *str;
 225         struct xenbus_transaction xbt;
 226         int err;
 227         int idx;
 228
 229         if (shutting_down != SHUTDOWN_INVALID)
 230                 return;
 231
 232  again:
 233         err = xenbus_transaction_start(&xbt);
 234         if (err)
 235                 return;
 236
 237         str = (char *)xenbus_read(xbt, "control", "shutdown", NULL);
 238         /* Ignore read errors and empty reads. */
 239         if (XENBUS_IS_ERR_READ(str)) {
 240                 xenbus_transaction_end(xbt, 1);
 241                 return;
 242         }
 243
 244         for (idx = 0; idx < ARRAY_SIZE(shutdown_handlers); idx++) {
 245                 if (strcmp(str, shutdown_handlers[idx].command) == 0)
 246                         break;
 247         }
 248
 249         /* Only acknowledge commands which we are prepared to handle. */
 250         if (idx < ARRAY_SIZE(shutdown_handlers))
 251                 xenbus_write(xbt, "control", "shutdown", "");
 252
 253         err = xenbus_transaction_end(xbt, 0);
 254         if (err == -EAGAIN) {
 255                 kfree(str);
 256                 goto again;
 257         }
 258
 259         if (idx < ARRAY_SIZE(shutdown_handlers)) {
 260                 shutdown_handlers[idx].cb();
 261         } else {
 262                 pr_info("Ignoring shutdown request: %s\n", str);
 263                 shutting_down = SHUTDOWN_INVALID;
 264         }
 265
 266         kfree(str);
 267 }
 268
 269 #ifdef CONFIG_MAGIC_SYSRQ
 270 static void sysrq_handler(struct xenbus_watch *watch, const char *path,
 271                           const char *token)
 272 {
 273         char sysrq_key = '\0';
 274         struct xenbus_transaction xbt;
 275         int err;
 276
 277  again:
 278         err = xenbus_transaction_start(&xbt);
 279         if (err)
 280                 return;
 281         err = xenbus_scanf(xbt, "control", "sysrq", "%c", &sysrq_key);
 282         if (err < 0) {
 283                 /*
 284                  * The Xenstore watch fires directly after registering it and
 285                  * after a suspend/resume cycle. So ENOENT is no error but
 286                  * might happen in those cases.
 287                  */
 288                 if (err != -ENOENT)
 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                 xenbus_printf(xbt, "control", "sysrq", "%c", '\0');
 297
 298         err = xenbus_transaction_end(xbt, 0);
 299         if (err == -EAGAIN)
 300                 goto again;
 301
 302         if (sysrq_key != '\0')
 303                 handle_sysrq(sysrq_key);
 304 }
 305
 306 static struct xenbus_watch sysrq_watch = {
 307         .node = "control/sysrq",
 308         .callback = sysrq_handler
 309 };
 310 #endif
 311
 312 static struct xenbus_watch shutdown_watch = {
 313         .node = "control/shutdown",
 314         .callback = shutdown_handler
 315 };
 316
 317 static struct notifier_block xen_reboot_nb = {
 318         .notifier_call = poweroff_nb,
 319 };
 320
 321 static int setup_shutdown_watcher(void)
 322 {
 323         int err;
 324         int idx;
 325 #define FEATURE_PATH_SIZE (SHUTDOWN_CMD_SIZE + sizeof("feature-"))
 326         char node[FEATURE_PATH_SIZE];
 327
 328         err = register_xenbus_watch(&shutdown_watch);
 329         if (err) {
 330                 pr_err("Failed to set shutdown watcher\n");
 331                 return err;
 332         }
 333
 334
 335 #ifdef CONFIG_MAGIC_SYSRQ
 336         err = register_xenbus_watch(&sysrq_watch);
 337         if (err) {
 338                 pr_err("Failed to set sysrq watcher\n");
 339                 return err;
 340         }
 341 #endif
 342
 343         for (idx = 0; idx < ARRAY_SIZE(shutdown_handlers); idx++) {
 344                 if (!shutdown_handlers[idx].flag)
 345                         continue;
 346                 snprintf(node, FEATURE_PATH_SIZE, "feature-%s",
 347                          shutdown_handlers[idx].command);
 348                 xenbus_printf(XBT_NIL, "control", node, "%u", 1);
 349         }
 350
 351         return 0;
 352 }
 353
 354 static int shutdown_event(struct notifier_block *notifier,
 355                           unsigned long event,
 356                           void *data)
 357 {
 358         setup_shutdown_watcher();
 359         return NOTIFY_DONE;
 360 }
 361
 362 int xen_setup_shutdown_event(void)
 363 {
 364         static struct notifier_block xenstore_notifier = {
 365                 .notifier_call = shutdown_event
 366         };
 367
 368         if (!xen_domain())
 369                 return -ENODEV;
 370         register_xenstore_notifier(&xenstore_notifier);
 371         register_reboot_notifier(&xen_reboot_nb);
 372
 373         return 0;
 374 }
 375 EXPORT_SYMBOL_GPL(xen_setup_shutdown_event);
 376
 377 subsys_initcall(xen_setup_shutdown_event);