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                 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
 205 static void do_reboot(void)
 206 {
 207         shutting_down = SHUTDOWN_POWEROFF; /* ? */
 208         ctrl_alt_del();
 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
 220 static void shutdown_handler(struct xenbus_watch *watch,
 221                              const char **vec, unsigned int len)
 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
 269 static void sysrq_handler(struct xenbus_watch *watch, const char **vec,
 270                           unsigned int len)
 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
 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
 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
 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);