| #define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt |
| |
| #include <linux/notifier.h> |
| |
| #include <xen/xen.h> |
| #include <xen/xenbus.h> |
| |
| #include <asm/xen/hypervisor.h> |
| #include <asm/cpu.h> |
| |
| static void enable_hotplug_cpu(int cpu) |
| { |
| if (!cpu_present(cpu)) |
| xen_arch_register_cpu(cpu); |
| |
| set_cpu_present(cpu, true); |
| } |
| |
| static void disable_hotplug_cpu(int cpu) |
| { |
| if (cpu_present(cpu)) |
| xen_arch_unregister_cpu(cpu); |
| |
| set_cpu_present(cpu, false); |
| } |
| |
| static int vcpu_online(unsigned int cpu) |
| { |
| int err; |
| char dir[16], state[16]; |
| |
| sprintf(dir, "cpu/%u", cpu); |
| err = xenbus_scanf(XBT_NIL, dir, "availability", "%15s", state); |
| if (err != 1) { |
| if (!xen_initial_domain()) |
| pr_err("Unable to read cpu state\n"); |
| return err; |
| } |
| |
| if (strcmp(state, "online") == 0) |
| return 1; |
| else if (strcmp(state, "offline") == 0) |
| return 0; |
| |
| pr_err("unknown state(%s) on CPU%d\n", state, cpu); |
| return -EINVAL; |
| } |
| static void vcpu_hotplug(unsigned int cpu) |
| { |
| if (!cpu_possible(cpu)) |
| return; |
| |
| switch (vcpu_online(cpu)) { |
| case 1: |
| enable_hotplug_cpu(cpu); |
| break; |
| case 0: |
| (void)cpu_down(cpu); |
| disable_hotplug_cpu(cpu); |
| break; |
| default: |
| break; |
| } |
| } |
| |
| static void handle_vcpu_hotplug_event(struct xenbus_watch *watch, |
| const char **vec, unsigned int len) |
| { |
| unsigned int cpu; |
| char *cpustr; |
| const char *node = vec[XS_WATCH_PATH]; |
| |
| cpustr = strstr(node, "cpu/"); |
| if (cpustr != NULL) { |
| sscanf(cpustr, "cpu/%u", &cpu); |
| vcpu_hotplug(cpu); |
| } |
| } |
| |
| static int setup_cpu_watcher(struct notifier_block *notifier, |
| unsigned long event, void *data) |
| { |
| int cpu; |
| static struct xenbus_watch cpu_watch = { |
| .node = "cpu", |
| .callback = handle_vcpu_hotplug_event}; |
| |
| (void)register_xenbus_watch(&cpu_watch); |
| |
| for_each_possible_cpu(cpu) { |
| if (vcpu_online(cpu) == 0) { |
| (void)cpu_down(cpu); |
| set_cpu_present(cpu, false); |
| } |
| } |
| |
| return NOTIFY_DONE; |
| } |
| |
| static int __init setup_vcpu_hotplug_event(void) |
| { |
| static struct notifier_block xsn_cpu = { |
| .notifier_call = setup_cpu_watcher }; |
| |
| #ifdef CONFIG_X86 |
| if (!xen_pv_domain()) |
| #else |
| if (!xen_domain()) |
| #endif |
| return -ENODEV; |
| |
| register_xenstore_notifier(&xsn_cpu); |
| |
| return 0; |
| } |
| |
| arch_initcall(setup_vcpu_hotplug_event); |
| |