| 1 | #define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt |
| 2 | |
| 3 | #include <linux/notifier.h> |
| 4 | |
| 5 | #include <xen/xen.h> |
| 6 | #include <xen/xenbus.h> |
| 7 | |
| 8 | #include <asm/xen/hypervisor.h> |
| 9 | #include <asm/cpu.h> |
| 10 | |
| 11 | static void enable_hotplug_cpu(int cpu) |
| 12 | { |
| 13 | if (!cpu_present(cpu)) |
| 14 | xen_arch_register_cpu(cpu); |
| 15 | |
| 16 | set_cpu_present(cpu, true); |
| 17 | } |
| 18 | |
| 19 | static void disable_hotplug_cpu(int cpu) |
| 20 | { |
| 21 | if (cpu_online(cpu)) { |
| 22 | lock_device_hotplug(); |
| 23 | device_offline(get_cpu_device(cpu)); |
| 24 | unlock_device_hotplug(); |
| 25 | } |
| 26 | if (cpu_present(cpu)) |
| 27 | xen_arch_unregister_cpu(cpu); |
| 28 | |
| 29 | set_cpu_present(cpu, false); |
| 30 | } |
| 31 | |
| 32 | static int vcpu_online(unsigned int cpu) |
| 33 | { |
| 34 | int err; |
| 35 | char dir[16], state[16]; |
| 36 | |
| 37 | sprintf(dir, "cpu/%u", cpu); |
| 38 | err = xenbus_scanf(XBT_NIL, dir, "availability", "%15s", state); |
| 39 | if (err != 1) { |
| 40 | if (!xen_initial_domain()) |
| 41 | pr_err("Unable to read cpu state\n"); |
| 42 | return err; |
| 43 | } |
| 44 | |
| 45 | if (strcmp(state, "online") == 0) |
| 46 | return 1; |
| 47 | else if (strcmp(state, "offline") == 0) |
| 48 | return 0; |
| 49 | |
| 50 | pr_err("unknown state(%s) on CPU%d\n", state, cpu); |
| 51 | return -EINVAL; |
| 52 | } |
| 53 | static void vcpu_hotplug(unsigned int cpu) |
| 54 | { |
| 55 | if (!cpu_possible(cpu)) |
| 56 | return; |
| 57 | |
| 58 | switch (vcpu_online(cpu)) { |
| 59 | case 1: |
| 60 | enable_hotplug_cpu(cpu); |
| 61 | break; |
| 62 | case 0: |
| 63 | disable_hotplug_cpu(cpu); |
| 64 | break; |
| 65 | default: |
| 66 | break; |
| 67 | } |
| 68 | } |
| 69 | |
| 70 | static void handle_vcpu_hotplug_event(struct xenbus_watch *watch, |
| 71 | const char **vec, unsigned int len) |
| 72 | { |
| 73 | unsigned int cpu; |
| 74 | char *cpustr; |
| 75 | const char *node = vec[XS_WATCH_PATH]; |
| 76 | |
| 77 | cpustr = strstr(node, "cpu/"); |
| 78 | if (cpustr != NULL) { |
| 79 | sscanf(cpustr, "cpu/%u", &cpu); |
| 80 | vcpu_hotplug(cpu); |
| 81 | } |
| 82 | } |
| 83 | |
| 84 | static int setup_cpu_watcher(struct notifier_block *notifier, |
| 85 | unsigned long event, void *data) |
| 86 | { |
| 87 | int cpu; |
| 88 | static struct xenbus_watch cpu_watch = { |
| 89 | .node = "cpu", |
| 90 | .callback = handle_vcpu_hotplug_event}; |
| 91 | |
| 92 | (void)register_xenbus_watch(&cpu_watch); |
| 93 | |
| 94 | for_each_possible_cpu(cpu) { |
| 95 | if (vcpu_online(cpu) == 0) { |
| 96 | (void)cpu_down(cpu); |
| 97 | set_cpu_present(cpu, false); |
| 98 | } |
| 99 | } |
| 100 | |
| 101 | return NOTIFY_DONE; |
| 102 | } |
| 103 | |
| 104 | static int __init setup_vcpu_hotplug_event(void) |
| 105 | { |
| 106 | static struct notifier_block xsn_cpu = { |
| 107 | .notifier_call = setup_cpu_watcher }; |
| 108 | |
| 109 | #ifdef CONFIG_X86 |
| 110 | if (!xen_pv_domain()) |
| 111 | #else |
| 112 | if (!xen_domain()) |
| 113 | #endif |
| 114 | return -ENODEV; |
| 115 | |
| 116 | register_xenstore_notifier(&xsn_cpu); |
| 117 | |
| 118 | return 0; |
| 119 | } |
| 120 | |
| 121 | arch_initcall(setup_vcpu_hotplug_event); |
| 122 | |