1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * cpuidle driver for haltpoll governor. 4 * 5 * Copyright 2019 Red Hat, Inc. and/or its affiliates. 6 * 7 * This work is licensed under the terms of the GNU GPL, version 2. See 8 * the COPYING file in the top-level directory. 9 * 10 * Authors: Marcelo Tosatti <mtosatti@redhat.com> 11 */ 12 13 #include <linux/init.h> 14 #include <linux/cpu.h> 15 #include <linux/cpuidle.h> 16 #include <linux/module.h> 17 #include <linux/sched/idle.h> 18 #include <linux/kvm_para.h> 19 #include <linux/cpuidle_haltpoll.h> 20 21 static bool force __read_mostly; 22 module_param(force, bool, 0444); 23 MODULE_PARM_DESC(force, "Load unconditionally"); 24 25 static struct cpuidle_device __percpu *haltpoll_cpuidle_devices; 26 static enum cpuhp_state haltpoll_hp_state; 27 28 static __cpuidle int default_enter_idle(struct cpuidle_device *dev, 29 struct cpuidle_driver *drv, int index) 30 { 31 if (current_clr_polling_and_test()) 32 return index; 33 34 arch_cpu_idle(); 35 return index; 36 } 37 38 static struct cpuidle_driver haltpoll_driver = { 39 .name = "haltpoll", 40 .governor = "haltpoll", 41 .states = { 42 { /* entry 0 is for polling */ }, 43 { 44 .enter = default_enter_idle, 45 .exit_latency = 1, 46 .target_residency = 1, 47 .power_usage = -1, 48 .name = "haltpoll idle", 49 .desc = "default architecture idle", 50 }, 51 }, 52 .safe_state_index = 0, 53 .state_count = 2, 54 }; 55 56 static int haltpoll_cpu_online(unsigned int cpu) 57 { 58 struct cpuidle_device *dev; 59 60 dev = per_cpu_ptr(haltpoll_cpuidle_devices, cpu); 61 if (!dev->registered) { 62 dev->cpu = cpu; 63 if (cpuidle_register_device(dev)) { 64 pr_notice("cpuidle_register_device %d failed!\n", cpu); 65 return -EIO; 66 } 67 arch_haltpoll_enable(cpu); 68 } 69 70 return 0; 71 } 72 73 static int haltpoll_cpu_offline(unsigned int cpu) 74 { 75 struct cpuidle_device *dev; 76 77 dev = per_cpu_ptr(haltpoll_cpuidle_devices, cpu); 78 if (dev->registered) { 79 arch_haltpoll_disable(cpu); 80 cpuidle_unregister_device(dev); 81 } 82 83 return 0; 84 } 85 86 static void haltpoll_uninit(void) 87 { 88 if (haltpoll_hp_state) 89 cpuhp_remove_state(haltpoll_hp_state); 90 cpuidle_unregister_driver(&haltpoll_driver); 91 92 free_percpu(haltpoll_cpuidle_devices); 93 haltpoll_cpuidle_devices = NULL; 94 } 95 96 static bool haltpoll_want(void) 97 { 98 return kvm_para_has_hint(KVM_HINTS_REALTIME) || force; 99 } 100 101 static int __init haltpoll_init(void) 102 { 103 int ret; 104 struct cpuidle_driver *drv = &haltpoll_driver; 105 106 /* Do not load haltpoll if idle= is passed */ 107 if (boot_option_idle_override != IDLE_NO_OVERRIDE) 108 return -ENODEV; 109 110 if (!kvm_para_available() || !haltpoll_want()) 111 return -ENODEV; 112 113 cpuidle_poll_state_init(drv); 114 115 ret = cpuidle_register_driver(drv); 116 if (ret < 0) 117 return ret; 118 119 haltpoll_cpuidle_devices = alloc_percpu(struct cpuidle_device); 120 if (haltpoll_cpuidle_devices == NULL) { 121 cpuidle_unregister_driver(drv); 122 return -ENOMEM; 123 } 124 125 ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "cpuidle/haltpoll:online", 126 haltpoll_cpu_online, haltpoll_cpu_offline); 127 if (ret < 0) { 128 haltpoll_uninit(); 129 } else { 130 haltpoll_hp_state = ret; 131 ret = 0; 132 } 133 134 return ret; 135 } 136 137 static void __exit haltpoll_exit(void) 138 { 139 haltpoll_uninit(); 140 } 141 142 module_init(haltpoll_init); 143 module_exit(haltpoll_exit); 144 MODULE_LICENSE("GPL"); 145 MODULE_AUTHOR("Marcelo Tosatti <mtosatti@redhat.com>"); 146