91 lines
1.7 KiB
C
91 lines
1.7 KiB
C
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#include <linux/notifier.h>
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#include <xen/xenbus.h>
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#include <asm-x86/xen/hypervisor.h>
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#include <asm/cpu.h>
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static void enable_hotplug_cpu(int cpu)
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{
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if (!cpu_present(cpu))
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arch_register_cpu(cpu);
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cpu_set(cpu, cpu_present_map);
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}
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static void disable_hotplug_cpu(int cpu)
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{
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if (cpu_present(cpu))
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arch_unregister_cpu(cpu);
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cpu_clear(cpu, cpu_present_map);
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}
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static void vcpu_hotplug(unsigned int cpu)
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{
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int err;
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char dir[32], state[32];
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if (!cpu_possible(cpu))
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return;
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sprintf(dir, "cpu/%u", cpu);
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err = xenbus_scanf(XBT_NIL, dir, "availability", "%s", state);
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if (err != 1) {
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printk(KERN_ERR "XENBUS: Unable to read cpu state\n");
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return;
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}
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if (strcmp(state, "online") == 0) {
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enable_hotplug_cpu(cpu);
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} else if (strcmp(state, "offline") == 0) {
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(void)cpu_down(cpu);
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disable_hotplug_cpu(cpu);
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} else {
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printk(KERN_ERR "XENBUS: unknown state(%s) on CPU%d\n",
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state, cpu);
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}
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}
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static void handle_vcpu_hotplug_event(struct xenbus_watch *watch,
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const char **vec, unsigned int len)
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{
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unsigned int cpu;
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char *cpustr;
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const char *node = vec[XS_WATCH_PATH];
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cpustr = strstr(node, "cpu/");
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if (cpustr != NULL) {
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sscanf(cpustr, "cpu/%u", &cpu);
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vcpu_hotplug(cpu);
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}
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}
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static int setup_cpu_watcher(struct notifier_block *notifier,
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unsigned long event, void *data)
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{
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static struct xenbus_watch cpu_watch = {
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.node = "cpu",
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.callback = handle_vcpu_hotplug_event};
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(void)register_xenbus_watch(&cpu_watch);
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return NOTIFY_DONE;
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}
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static int __init setup_vcpu_hotplug_event(void)
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{
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static struct notifier_block xsn_cpu = {
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.notifier_call = setup_cpu_watcher };
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if (!is_running_on_xen())
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return -ENODEV;
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register_xenstore_notifier(&xsn_cpu);
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return 0;
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}
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arch_initcall(setup_vcpu_hotplug_event);
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