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