cpuidle: add cpuidle-haltpoll driver module parameter

hulk inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I6404X?from=project-issue
CVE: NA

---------------------------

To ensure energy efficiency, haltpoll is disabled by default.
But In some performance scenarios, you can enable haltpoll using
the following methods:

echo Y > /sys/module/cpuidle_haltpoll/parameters/force
Signed-off-by: NXiangyou Xie <xiexiangyou@huawei.com>
Reviewed-by: NKeqian Zhu <zhukeqian1@huawei.com>
Reviewed-by: NQingqing Li <liqingqing3@huawei.com>
Reviewed-by: Nchenhui <judy.chenhui@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

drivers/cpuidle/cpuidle-haltpoll.c

@@ -18,9 +18,17 @@
 #include <linux/kvm_para.h>
 #include <linux/cpuidle_haltpoll.h>
 
-static bool force __read_mostly;
-module_param(force, bool, 0444);
-MODULE_PARM_DESC(force, "Load unconditionally");
+static bool force;
+MODULE_PARM_DESC(force, "bool, enable haltpoll driver");
+static int enable_haltpoll_driver(const char *val, const struct kernel_param *kp);
+static int register_haltpoll_driver(void);
+static void unregister_haltpoll_driver(void);
+
+static const struct kernel_param_ops enable_haltpoll_ops = {
+	.set = enable_haltpoll_driver,
+	.get = param_get_bool,
+};
+module_param_cb(force, &enable_haltpoll_ops, &force, 0644);
 
 static struct cpuidle_device __percpu *haltpoll_cpuidle_devices;
 static enum cpuhp_state haltpoll_hp_state;
@@ -36,6 +44,42 @@ static int default_enter_idle(struct cpuidle_device *dev,
 	return index;
 }
 
+
+static int enable_haltpoll_driver(const char *val, const struct kernel_param *kp)
+{
+#ifdef CONFIG_ARM64
+	int ret;
+	bool do_enable;
+
+	if (!val)
+		return 0;
+
+	ret = strtobool(val, &do_enable);
+
+	if (ret || force == do_enable)
+		return ret;
+
+	if (do_enable) {
+		ret = register_haltpoll_driver();
+
+		if (!ret) {
+			pr_info("Enable haltpoll driver.\n");
+			force = 1;
+		} else {
+			pr_err("Fail to enable haltpoll driver.\n");
+		}
+	} else {
+		unregister_haltpoll_driver();
+		force = 0;
+		pr_info("Unregister haltpoll driver.\n");
+	}
+
+	return ret;
+#else
+	return -1;
+#endif
+}
+
 static struct cpuidle_driver haltpoll_driver = {
 	.name = "haltpoll",
 	.governor = "haltpoll",
@@ -84,22 +128,18 @@ static int haltpoll_cpu_offline(unsigned int cpu)
 	return 0;
 }
 
-static void haltpoll_uninit(void)
-{
-	if (haltpoll_hp_state)
-		cpuhp_remove_state(haltpoll_hp_state);
-	cpuidle_unregister_driver(&haltpoll_driver);
-
-	free_percpu(haltpoll_cpuidle_devices);
-	haltpoll_cpuidle_devices = NULL;
-}
 
 static bool haltpoll_want(void)
 {
 	return kvm_para_has_hint(KVM_HINTS_REALTIME);
 }
 
-static int __init haltpoll_init(void)
+static void haltpoll_uninit(void)
+{
+	unregister_haltpoll_driver();
+}
+
+static int register_haltpoll_driver(void)
 {
 	int ret;
 	struct cpuidle_driver *drv = &haltpoll_driver;
@@ -112,9 +152,6 @@ static int __init haltpoll_init(void)
 
 	cpuidle_poll_state_init(drv);
 
-	if (!force && (!kvm_para_available() || !haltpoll_want()))
-		return -ENODEV;
-
 	ret = cpuidle_register_driver(drv);
 	if (ret < 0)
 		return ret;
@@ -137,9 +174,35 @@ static int __init haltpoll_init(void)
 	return ret;
 }
 
+static void unregister_haltpoll_driver(void)
+{
+	if (haltpoll_hp_state)
+		cpuhp_remove_state(haltpoll_hp_state);
+	cpuidle_unregister_driver(&haltpoll_driver);
+
+	free_percpu(haltpoll_cpuidle_devices);
+	haltpoll_cpuidle_devices = NULL;
+
+}
+
+static int __init haltpoll_init(void)
+{
+	int ret = 0;
+#ifdef CONFIG_X86
+	/* Do not load haltpoll if idle= is passed */
+	if (boot_option_idle_override != IDLE_NO_OVERRIDE)
+		return -ENODEV;
+#endif
+	if (force || (haltpoll_want() && kvm_para_available()))
+		ret = register_haltpoll_driver();
+
+	return ret;
+}
+
 static void __exit haltpoll_exit(void)
 {
-	haltpoll_uninit();
+	if (haltpoll_cpuidle_devices)
+		haltpoll_uninit();
 }
 
 module_init(haltpoll_init);

drivers/cpuidle/governors/haltpoll.c

@@ -39,7 +39,7 @@ module_param(guest_halt_poll_grow_start, uint, 0644);
 static bool guest_halt_poll_allow_shrink __read_mostly = true;
 module_param(guest_halt_poll_allow_shrink, bool, 0644);
 
-static bool enable __read_mostly;
+static bool enable __read_mostly = true;
 module_param(enable, bool, 0444);
 MODULE_PARM_DESC(enable, "Load unconditionally");
 
@@ -144,7 +144,7 @@ static struct cpuidle_governor haltpoll_governor = {
 
 static int __init init_haltpoll(void)
 {
-	if (kvm_para_available() || enable)
+	if (enable)
 		return cpuidle_register_governor(&haltpoll_governor);
 
 	return 0;