1 files changed, 68 insertions, 9 deletions

diff --git a/kernel/cpu.c b/kernel/cpu.c
index 85ff5e26e23b..427ec803d455 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -8,6 +8,7 @@
 #include <linux/init.h>
 #include <linux/notifier.h>
 #include <linux/sched.h>
+#include <linux/sched/smt.h>
 #include <linux/unistd.h>
 #include <linux/cpu.h>
 #include <linux/oom.h>
@@ -24,6 +25,8 @@
 #include <linux/irq.h>
 #include <trace/events/power.h>
 
+#include <trace/events/sched.h>
+
 #include "smpboot.h"
 
 #ifdef CONFIG_SMP
@@ -183,15 +186,28 @@ void cpu_hotplug_disable(void)
 }
 EXPORT_SYMBOL_GPL(cpu_hotplug_disable);
 
+static void __cpu_hotplug_enable(void)
+{
+	if (WARN_ONCE(!cpu_hotplug_disabled, "Unbalanced cpu hotplug enable\n"))
+		return;
+	cpu_hotplug_disabled--;
+}
+
 void cpu_hotplug_enable(void)
 {
 	cpu_maps_update_begin();
-	WARN_ON(--cpu_hotplug_disabled < 0);
+	__cpu_hotplug_enable();
 	cpu_maps_update_done();
 }
 EXPORT_SYMBOL_GPL(cpu_hotplug_enable);
 #endif	/* CONFIG_HOTPLUG_CPU */
 
+/*
+ * Architectures that need SMT-specific errata handling during SMT hotplug
+ * should override this.
+ */
+void __weak arch_smt_update(void) { }
+
 /* Need to know about CPUs going up/down? */
 int register_cpu_notifier(struct notifier_block *nb)
 {
@@ -223,12 +239,6 @@ static int cpu_notify(unsigned long val, void *v)
 	return __cpu_notify(val, v, -1, NULL);
 }
 
-#ifdef CONFIG_HOTPLUG_CPU
-
-static void cpu_notify_nofail(unsigned long val, void *v)
-{
-	BUG_ON(cpu_notify(val, v));
-}
 EXPORT_SYMBOL(register_cpu_notifier);
 EXPORT_SYMBOL(__register_cpu_notifier);
 
@@ -246,6 +256,12 @@ void __unregister_cpu_notifier(struct notifier_block *nb)
 }
 EXPORT_SYMBOL(__unregister_cpu_notifier);
 
+#ifdef CONFIG_HOTPLUG_CPU
+static void cpu_notify_nofail(unsigned long val, void *v)
+{
+	BUG_ON(cpu_notify(val, v));
+}
+
 /**
  * clear_tasks_mm_cpumask - Safely clear tasks' mm_cpumask for a CPU
  * @cpu: a CPU id
@@ -425,8 +441,10 @@ static int _cpu_down(unsigned int cpu, int tasks_frozen)
 
 out_release:
 	cpu_hotplug_done();
+	trace_sched_cpu_hotplug(cpu, err, 0);
 	if (!err)
 		cpu_notify_nofail(CPU_POST_DEAD | mod, hcpu);
+	arch_smt_update();
 	return err;
 }
 
@@ -530,7 +548,8 @@ out_notify:
 		__cpu_notify(CPU_UP_CANCELED | mod, hcpu, nr_calls, NULL);
 out:
 	cpu_hotplug_done();
-
+	trace_sched_cpu_hotplug(cpu, ret, 1);
+	arch_smt_update();
 	return ret;
 }
 
@@ -623,10 +642,11 @@ void __weak arch_enable_nonboot_cpus_end(void)
 void enable_nonboot_cpus(void)
 {
 	int cpu, error;
+	struct device *cpu_device;
 
 	/* Allow everyone to use the CPU hotplug again */
 	cpu_maps_update_begin();
-	WARN_ON(--cpu_hotplug_disabled < 0);
+	__cpu_hotplug_enable();
 	if (cpumask_empty(frozen_cpus))
 		goto out;
 
@@ -640,6 +660,12 @@ void enable_nonboot_cpus(void)
 		trace_suspend_resume(TPS("CPU_ON"), cpu, false);
 		if (!error) {
 			pr_info("CPU%d is up\n", cpu);
+			cpu_device = get_cpu_device(cpu);
+			if (!cpu_device)
+				pr_err("%s: failed to get cpu%d device\n",
+				       __func__, cpu);
+			else
+				kobject_uevent(&cpu_device->kobj, KOBJ_ONLINE);
 			continue;
 		}
 		pr_warn("Error taking CPU%d up: %d\n", cpu, error);
@@ -827,3 +853,36 @@ void init_cpu_online(const struct cpumask *src)
 {
 	cpumask_copy(to_cpumask(cpu_online_bits), src);
 }
+
+enum cpu_mitigations cpu_mitigations = CPU_MITIGATIONS_AUTO;
+
+static int __init mitigations_parse_cmdline(char *arg)
+{
+	if (!strcmp(arg, "off"))
+		cpu_mitigations = CPU_MITIGATIONS_OFF;
+	else if (!strcmp(arg, "auto"))
+		cpu_mitigations = CPU_MITIGATIONS_AUTO;
+
+	return 0;
+}
+early_param("mitigations", mitigations_parse_cmdline);
+
+static ATOMIC_NOTIFIER_HEAD(idle_notifier);
+
+void idle_notifier_register(struct notifier_block *n)
+{
+	atomic_notifier_chain_register(&idle_notifier, n);
+}
+EXPORT_SYMBOL_GPL(idle_notifier_register);
+
+void idle_notifier_unregister(struct notifier_block *n)
+{
+	atomic_notifier_chain_unregister(&idle_notifier, n);
+}
+EXPORT_SYMBOL_GPL(idle_notifier_unregister);
+
+void idle_notifier_call_chain(unsigned long val)
+{
+	atomic_notifier_call_chain(&idle_notifier, val, NULL);
+}
+EXPORT_SYMBOL_GPL(idle_notifier_call_chain);