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 int default_enter_idle(struct cpuidle_device *dev, 29 struct cpuidle_driver *drv, int index) 30 { 31 if (current_clr_polling_and_test()) { 32 local_irq_enable(); 33 return index; 34 } 35 default_idle(); 36 return index; 37 } 38 39 static struct cpuidle_driver haltpoll_driver = { 40 .name = "haltpoll", 41 .governor = "haltpoll", 42 .states = { 43 { /* entry 0 is for polling */ }, 44 { 45 .enter = default_enter_idle, 46 .exit_latency = 1, 47 .target_residency = 1, 48 .power_usage = -1, 49 .name = "haltpoll idle", 50 .desc = "default architecture idle", 51 }, 52 }, 53 .safe_state_index = 0, 54 .state_count = 2, 55 }; 56 57 static int haltpoll_cpu_online(unsigned int cpu) 58 { 59 struct cpuidle_device *dev; 60 61 dev = per_cpu_ptr(haltpoll_cpuidle_devices, cpu); 62 if (!dev->registered) { 63 dev->cpu = cpu; 64 if (cpuidle_register_device(dev)) { 65 pr_notice("cpuidle_register_device %d failed!\n", cpu); 66 return -EIO; 67 } 68 arch_haltpoll_enable(cpu); 69 } 70 71 return 0; 72 } 73 74 static int haltpoll_cpu_offline(unsigned int cpu) 75 { 76 struct cpuidle_device *dev; 77 78 dev = per_cpu_ptr(haltpoll_cpuidle_devices, cpu); 79 if (dev->registered) { 80 arch_haltpoll_disable(cpu); 81 cpuidle_unregister_device(dev); 82 } 83 84 return 0; 85 } 86 87 static void haltpoll_uninit(void) 88 { 89 if (haltpoll_hp_state) 90 cpuhp_remove_state(haltpoll_hp_state); 91 cpuidle_unregister_driver(&haltpoll_driver); 92 93 free_percpu(haltpoll_cpuidle_devices); 94 haltpoll_cpuidle_devices = NULL; 95 } 96 97 static bool haltpoll_want(void) 98 { 99 return kvm_para_has_hint(KVM_HINTS_REALTIME) || force; 100 } 101 102 static int __init haltpoll_init(void) 103 { 104 int ret; 105 struct cpuidle_driver *drv = &haltpoll_driver; 106 107 /* Do not load haltpoll if idle= is passed */ 108 if (boot_option_idle_override != IDLE_NO_OVERRIDE) 109 return -ENODEV; 110 111 if (!kvm_para_available() || !haltpoll_want()) 112 return -ENODEV; 113 114 cpuidle_poll_state_init(drv); 115 116 ret = cpuidle_register_driver(drv); 117 if (ret < 0) 118 return ret; 119 120 haltpoll_cpuidle_devices = alloc_percpu(struct cpuidle_device); 121 if (haltpoll_cpuidle_devices == NULL) { 122 cpuidle_unregister_driver(drv); 123 return -ENOMEM; 124 } 125 126 ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "cpuidle/haltpoll:online", 127 haltpoll_cpu_online, haltpoll_cpu_offline); 128 if (ret < 0) { 129 haltpoll_uninit(); 130 } else { 131 haltpoll_hp_state = ret; 132 ret = 0; 133 } 134 135 return ret; 136 } 137 138 static void __exit haltpoll_exit(void) 139 { 140 haltpoll_uninit(); 141 } 142 143 module_init(haltpoll_init); 144 module_exit(haltpoll_exit); 145 MODULE_LICENSE("GPL"); 146 MODULE_AUTHOR("Marcelo Tosatti <mtosatti@redhat.com>"); 147