1 files changed, 154 insertions, 23 deletions

diff --git a/kernel/cpu.c b/kernel/cpu.c
index 9c706af713fb..6ff2578ecf17 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -3,6 +3,7 @@
  *
  * This code is licenced under the GPL.
  */
+#include <linux/sched/mm.h>
 #include <linux/proc_fs.h>
 #include <linux/smp.h>
 #include <linux/init.h>
@@ -331,12 +332,12 @@ void lockdep_assert_cpus_held(void)
 
 static void lockdep_acquire_cpus_lock(void)
 {
-	rwsem_acquire(&cpu_hotplug_lock.rw_sem.dep_map, 0, 0, _THIS_IP_);
+	rwsem_acquire(&cpu_hotplug_lock.dep_map, 0, 0, _THIS_IP_);
 }
 
 static void lockdep_release_cpus_lock(void)
 {
-	rwsem_release(&cpu_hotplug_lock.rw_sem.dep_map, _THIS_IP_);
+	rwsem_release(&cpu_hotplug_lock.dep_map, _THIS_IP_);
 }
 
 /*
@@ -432,7 +433,7 @@ static inline bool cpu_smt_allowed(unsigned int cpu)
 	/*
 	 * On x86 it's required to boot all logical CPUs at least once so
 	 * that the init code can get a chance to set CR4.MCE on each
-	 * CPU. Otherwise, a broadacasted MCE observing CR4.MCE=0b on any
+	 * CPU. Otherwise, a broadcasted MCE observing CR4.MCE=0b on any
 	 * core will shutdown the machine.
 	 */
 	return !cpumask_test_cpu(cpu, &cpus_booted_once_mask);
@@ -564,6 +565,21 @@ static int bringup_cpu(unsigned int cpu)
 	return bringup_wait_for_ap(cpu);
 }
 
+static int finish_cpu(unsigned int cpu)
+{
+	struct task_struct *idle = idle_thread_get(cpu);
+	struct mm_struct *mm = idle->active_mm;
+
+	/*
+	 * idle_task_exit() will have switched to &init_mm, now
+	 * clean up any remaining active_mm state.
+	 */
+	if (mm != &init_mm)
+		idle->active_mm = &init_mm;
+	mmdrop(mm);
+	return 0;
+}
+
 /*
  * Hotplug state machine related functions
  */
@@ -1041,7 +1057,7 @@ static int cpu_down_maps_locked(unsigned int cpu, enum cpuhp_state target)
 	return _cpu_down(cpu, 0, target);
 }
 
-static int do_cpu_down(unsigned int cpu, enum cpuhp_state target)
+static int cpu_down(unsigned int cpu, enum cpuhp_state target)
 {
 	int err;
 
@@ -1051,11 +1067,72 @@ static int do_cpu_down(unsigned int cpu, enum cpuhp_state target)
 	return err;
 }
 
-int cpu_down(unsigned int cpu)
+/**
+ * cpu_device_down - Bring down a cpu device
+ * @dev: Pointer to the cpu device to offline
+ *
+ * This function is meant to be used by device core cpu subsystem only.
+ *
+ * Other subsystems should use remove_cpu() instead.
+ */
+int cpu_device_down(struct device *dev)
+{
+	return cpu_down(dev->id, CPUHP_OFFLINE);
+}
+
+int remove_cpu(unsigned int cpu)
 {
-	return do_cpu_down(cpu, CPUHP_OFFLINE);
+	int ret;
+
+	lock_device_hotplug();
+	ret = device_offline(get_cpu_device(cpu));
+	unlock_device_hotplug();
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(remove_cpu);
+
+void smp_shutdown_nonboot_cpus(unsigned int primary_cpu)
+{
+	unsigned int cpu;
+	int error;
+
+	cpu_maps_update_begin();
+
+	/*
+	 * Make certain the cpu I'm about to reboot on is online.
+	 *
+	 * This is inline to what migrate_to_reboot_cpu() already do.
+	 */
+	if (!cpu_online(primary_cpu))
+		primary_cpu = cpumask_first(cpu_online_mask);
+
+	for_each_online_cpu(cpu) {
+		if (cpu == primary_cpu)
+			continue;
+
+		error = cpu_down_maps_locked(cpu, CPUHP_OFFLINE);
+		if (error) {
+			pr_err("Failed to offline CPU%d - error=%d",
+				cpu, error);
+			break;
+		}
+	}
+
+	/*
+	 * Ensure all but the reboot CPU are offline.
+	 */
+	BUG_ON(num_online_cpus() > 1);
+
+	/*
+	 * Make sure the CPUs won't be enabled by someone else after this
+	 * point. Kexec will reboot to a new kernel shortly resetting
+	 * everything along the way.
+	 */
+	cpu_hotplug_disabled++;
+
+	cpu_maps_update_done();
 }
-EXPORT_SYMBOL(cpu_down);
 
 #else
 #define takedown_cpu		NULL
@@ -1124,8 +1201,8 @@ static int _cpu_up(unsigned int cpu, int tasks_frozen, enum cpuhp_state target)
 	}
 
 	/*
-	 * The caller of do_cpu_up might have raced with another
-	 * caller. Ignore it for now.
+	 * The caller of cpu_up() might have raced with another
+	 * caller. Nothing to do.
 	 */
 	if (st->state >= target)
 		goto out;
@@ -1169,7 +1246,7 @@ out:
 	return ret;
 }
 
-static int do_cpu_up(unsigned int cpu, enum cpuhp_state target)
+static int cpu_up(unsigned int cpu, enum cpuhp_state target)
 {
 	int err = 0;
 
@@ -1203,11 +1280,65 @@ out:
 	return err;
 }
 
-int cpu_up(unsigned int cpu)
+/**
+ * cpu_device_up - Bring up a cpu device
+ * @dev: Pointer to the cpu device to online
+ *
+ * This function is meant to be used by device core cpu subsystem only.
+ *
+ * Other subsystems should use add_cpu() instead.
+ */
+int cpu_device_up(struct device *dev)
+{
+	return cpu_up(dev->id, CPUHP_ONLINE);
+}
+
+int add_cpu(unsigned int cpu)
 {
-	return do_cpu_up(cpu, CPUHP_ONLINE);
+	int ret;
+
+	lock_device_hotplug();
+	ret = device_online(get_cpu_device(cpu));
+	unlock_device_hotplug();
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(add_cpu);
+
+/**
+ * bringup_hibernate_cpu - Bring up the CPU that we hibernated on
+ * @sleep_cpu: The cpu we hibernated on and should be brought up.
+ *
+ * On some architectures like arm64, we can hibernate on any CPU, but on
+ * wake up the CPU we hibernated on might be offline as a side effect of
+ * using maxcpus= for example.
+ */
+int bringup_hibernate_cpu(unsigned int sleep_cpu)
+{
+	int ret;
+
+	if (!cpu_online(sleep_cpu)) {
+		pr_info("Hibernated on a CPU that is offline! Bringing CPU up.\n");
+		ret = cpu_up(sleep_cpu, CPUHP_ONLINE);
+		if (ret) {
+			pr_err("Failed to bring hibernate-CPU up!\n");
+			return ret;
+		}
+	}
+	return 0;
+}
+
+void bringup_nonboot_cpus(unsigned int setup_max_cpus)
+{
+	unsigned int cpu;
+
+	for_each_present_cpu(cpu) {
+		if (num_online_cpus() >= setup_max_cpus)
+			break;
+		if (!cpu_online(cpu))
+			cpu_up(cpu, CPUHP_ONLINE);
+	}
 }
-EXPORT_SYMBOL_GPL(cpu_up);
 
 #ifdef CONFIG_PM_SLEEP_SMP
 static cpumask_var_t frozen_cpus;
@@ -1261,8 +1392,8 @@ int freeze_secondary_cpus(int primary)
 
 	/*
 	 * Make sure the CPUs won't be enabled by someone else. We need to do
-	 * this even in case of failure as all disable_nonboot_cpus() users are
-	 * supposed to do enable_nonboot_cpus() on the failure path.
+	 * this even in case of failure as all freeze_secondary_cpus() users are
+	 * supposed to do thaw_secondary_cpus() on the failure path.
 	 */
 	cpu_hotplug_disabled++;
 
@@ -1270,15 +1401,15 @@ int freeze_secondary_cpus(int primary)
 	return error;
 }
 
-void __weak arch_enable_nonboot_cpus_begin(void)
+void __weak arch_thaw_secondary_cpus_begin(void)
 {
 }
 
-void __weak arch_enable_nonboot_cpus_end(void)
+void __weak arch_thaw_secondary_cpus_end(void)
 {
 }
 
-void enable_nonboot_cpus(void)
+void thaw_secondary_cpus(void)
 {
 	int cpu, error;
 
@@ -1290,7 +1421,7 @@ void enable_nonboot_cpus(void)
 
 	pr_info("Enabling non-boot CPUs ...\n");
 
-	arch_enable_nonboot_cpus_begin();
+	arch_thaw_secondary_cpus_begin();
 
 	for_each_cpu(cpu, frozen_cpus) {
 		trace_suspend_resume(TPS("CPU_ON"), cpu, true);
@@ -1303,7 +1434,7 @@ void enable_nonboot_cpus(void)
 		pr_warn("Error taking CPU%d up: %d\n", cpu, error);
 	}
 
-	arch_enable_nonboot_cpus_end();
+	arch_thaw_secondary_cpus_end();
 
 	cpumask_clear(frozen_cpus);
 out:
@@ -1434,7 +1565,7 @@ static struct cpuhp_step cpuhp_hp_states[] = {
 	[CPUHP_BRINGUP_CPU] = {
 		.name			= "cpu:bringup",
 		.startup.single		= bringup_cpu,
-		.teardown.single	= NULL,
+		.teardown.single	= finish_cpu,
 		.cant_stop		= true,
 	},
 	/* Final state before CPU kills itself */
@@ -2028,9 +2159,9 @@ static ssize_t write_cpuhp_target(struct device *dev,
 		goto out;
 
 	if (st->state < target)
-		ret = do_cpu_up(dev->id, target);
+		ret = cpu_up(dev->id, target);
 	else
-		ret = do_cpu_down(dev->id, target);
+		ret = cpu_down(dev->id, target);
 out:
 	unlock_device_hotplug();
 	return ret ? ret : count;