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   1 /*
   2  * Handle extern requests for shutdown, reboot and sysrq
   3  */
   4 #include <linux/kernel.h>
   5 #include <linux/err.h>
   6 #include <linux/slab.h>
   7 #include <linux/reboot.h>
   8 #include <linux/sysrq.h>
   9 #include <linux/stop_machine.h>
  10 #include <linux/freezer.h>
  11
  12 #include <xen/xenbus.h>
  13 #include <xen/grant_table.h>
  14 #include <xen/events.h>
  15 #include <xen/hvc-console.h>
  16 #include <xen/xen-ops.h>
  17
  18 #include <asm/xen/hypercall.h>
  19 #include <asm/xen/page.h>
  20
  21 enum shutdown_state {
  22         SHUTDOWN_INVALID = -1,
  23         SHUTDOWN_POWEROFF = 0,
  24         SHUTDOWN_SUSPEND = 2,
  25         /* Code 3 is SHUTDOWN_CRASH, which we don't use because the domain can only
  26            report a crash, not be instructed to crash!
  27            HALT is the same as POWEROFF, as far as we're concerned.  The tools use
  28            the distinction when we return the reason code to them.  */
  29          SHUTDOWN_HALT = 4,
  30 };
  31
  32 /* Ignore multiple shutdown requests. */
  33 static enum shutdown_state shutting_down = SHUTDOWN_INVALID;
  34
  35 #ifdef CONFIG_PM_SLEEP
  36 static int xen_suspend(void *data)
  37 {
  38         int *cancelled = data;
  39         int err;
  40
  41         BUG_ON(!irqs_disabled());
  42
  43         err = sysdev_suspend(PMSG_SUSPEND);
  44         if (err) {
  45                 printk(KERN_ERR "xen_suspend: sysdev_suspend failed: %d\n",
  46                         err);
  47                 return err;
  48         }
  49
  50         xen_mm_pin_all();
  51         gnttab_suspend();
  52         xen_pre_suspend();
  53
  54         /*
  55          * This hypercall returns 1 if suspend was cancelled
  56          * or the domain was merely checkpointed, and 0 if it
  57          * is resuming in a new domain.
  58          */
  59         *cancelled = HYPERVISOR_suspend(virt_to_mfn(xen_start_info));
  60
  61         xen_post_suspend(*cancelled);
  62         gnttab_resume();
  63         xen_mm_unpin_all();
  64
  65         if (!*cancelled) {
  66                 xen_irq_resume();
  67                 xen_console_resume();
  68                 xen_timer_resume();
  69         }
  70
  71         sysdev_resume();
  72
  73         return 0;
  74 }
  75
  76 static void do_suspend(void)
  77 {
  78         int err;
  79         int cancelled = 1;
  80
  81         shutting_down = SHUTDOWN_SUSPEND;
  82
  83         err = stop_machine_create();
  84         if (err) {
  85                 printk(KERN_ERR "xen suspend: failed to setup stop_machine %d\n", err);
  86                 goto out;
  87         }
  88
  89 #ifdef CONFIG_PREEMPT
  90         /* If the kernel is preemptible, we need to freeze all the processes
  91            to prevent them from being in the middle of a pagetable update
  92            during suspend. */
  93         err = freeze_processes();
  94         if (err) {
  95                 printk(KERN_ERR "xen suspend: freeze failed %d\n", err);
  96                 goto out_destroy_sm;
  97         }
  98 #endif
  99
 100         err = dpm_suspend_start(PMSG_SUSPEND);
 101         if (err) {
 102                 printk(KERN_ERR "xen suspend: dpm_suspend_start %d\n", err);
 103                 goto out_thaw;
 104         }
 105
 106         printk(KERN_DEBUG "suspending xenstore...\n");
 107         xs_suspend();
 108
 109         err = dpm_suspend_noirq(PMSG_SUSPEND);
 110         if (err) {
 111                 printk(KERN_ERR "dpm_suspend_noirq failed: %d\n", err);
 112                 goto out_resume;
 113         }
 114
 115         err = stop_machine(xen_suspend, &cancelled, cpumask_of(0));
 116
 117         dpm_resume_noirq(PMSG_RESUME);
 118
 119         if (err) {
 120                 printk(KERN_ERR "failed to start xen_suspend: %d\n", err);
 121                 cancelled = 1;
 122         }
 123
 124 out_resume:
 125         if (!cancelled) {
 126                 xen_arch_resume();
 127                 xs_resume();
 128         } else
 129                 xs_suspend_cancel();
 130
 131         dpm_resume_end(PMSG_RESUME);
 132
 133         /* Make sure timer events get retriggered on all CPUs */
 134         clock_was_set();
 135
 136 out_thaw:
 137 #ifdef CONFIG_PREEMPT
 138         thaw_processes();
 139
 140 out_destroy_sm:
 141 #endif
 142         stop_machine_destroy();
 143
 144 out:
 145         shutting_down = SHUTDOWN_INVALID;
 146 }
 147 #endif  /* CONFIG_PM_SLEEP */
 148
 149 static void shutdown_handler(struct xenbus_watch *watch,
 150                              const char **vec, unsigned int len)
 151 {
 152         char *str;
 153         struct xenbus_transaction xbt;
 154         int err;
 155
 156         if (shutting_down != SHUTDOWN_INVALID)
 157                 return;
 158
 159  again:
 160         err = xenbus_transaction_start(&xbt);
 161         if (err)
 162                 return;
 163
 164         str = (char *)xenbus_read(xbt, "control", "shutdown", NULL);
 165         /* Ignore read errors and empty reads. */
 166         if (XENBUS_IS_ERR_READ(str)) {
 167                 xenbus_transaction_end(xbt, 1);
 168                 return;
 169         }
 170
 171         xenbus_write(xbt, "control", "shutdown", "");
 172
 173         err = xenbus_transaction_end(xbt, 0);
 174         if (err == -EAGAIN) {
 175                 kfree(str);
 176                 goto again;
 177         }
 178
 179         if (strcmp(str, "poweroff") == 0 ||
 180             strcmp(str, "halt") == 0) {
 181                 shutting_down = SHUTDOWN_POWEROFF;
 182                 orderly_poweroff(false);
 183         } else if (strcmp(str, "reboot") == 0) {
 184                 shutting_down = SHUTDOWN_POWEROFF; /* ? */
 185                 ctrl_alt_del();
 186 #ifdef CONFIG_PM_SLEEP
 187         } else if (strcmp(str, "suspend") == 0) {
 188                 do_suspend();
 189 #endif
 190         } else {
 191                 printk(KERN_INFO "Ignoring shutdown request: %s\n", str);
 192                 shutting_down = SHUTDOWN_INVALID;
 193         }
 194
 195         kfree(str);
 196 }
 197
 198 static void sysrq_handler(struct xenbus_watch *watch, const char **vec,
 199                           unsigned int len)
 200 {
 201         char sysrq_key = '\0';
 202         struct xenbus_transaction xbt;
 203         int err;
 204
 205  again:
 206         err = xenbus_transaction_start(&xbt);
 207         if (err)
 208                 return;
 209         if (!xenbus_scanf(xbt, "control", "sysrq", "%c", &sysrq_key)) {
 210                 printk(KERN_ERR "Unable to read sysrq code in "
 211                        "control/sysrq\n");
 212                 xenbus_transaction_end(xbt, 1);
 213                 return;
 214         }
 215
 216         if (sysrq_key != '\0')
 217                 xenbus_printf(xbt, "control", "sysrq", "%c", '\0');
 218
 219         err = xenbus_transaction_end(xbt, 0);
 220         if (err == -EAGAIN)
 221                 goto again;
 222
 223         if (sysrq_key != '\0')
 224                 handle_sysrq(sysrq_key, NULL);
 225 }
 226
 227 static struct xenbus_watch shutdown_watch = {
 228         .node = "control/shutdown",
 229         .callback = shutdown_handler
 230 };
 231
 232 static struct xenbus_watch sysrq_watch = {
 233         .node = "control/sysrq",
 234         .callback = sysrq_handler
 235 };
 236
 237 static int setup_shutdown_watcher(void)
 238 {
 239         int err;
 240
 241         err = register_xenbus_watch(&shutdown_watch);
 242         if (err) {
 243                 printk(KERN_ERR "Failed to set shutdown watcher\n");
 244                 return err;
 245         }
 246
 247         err = register_xenbus_watch(&sysrq_watch);
 248         if (err) {
 249                 printk(KERN_ERR "Failed to set sysrq watcher\n");
 250                 return err;
 251         }
 252
 253         return 0;
 254 }
 255
 256 static int shutdown_event(struct notifier_block *notifier,
 257                           unsigned long event,
 258                           void *data)
 259 {
 260         setup_shutdown_watcher();
 261         return NOTIFY_DONE;
 262 }
 263
 264 static int __init setup_shutdown_event(void)
 265 {
 266         static struct notifier_block xenstore_notifier = {
 267                 .notifier_call = shutdown_event
 268         };
 269         register_xenstore_notifier(&xenstore_notifier);
 270
 271         return 0;
 272 }
 273
 274 subsys_initcall(setup_shutdown_event);