arch/riscv/kernel/cpu-hotplug.c

root/arch/riscv/kernel/cpu-hotplug.c
// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2020 Western Digital Corporation or its affiliates.
 */

#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/sched.h>
#include <linux/err.h>
#include <linux/irq.h>
#include <linux/cpuhotplug.h>
#include <linux/cpu.h>
#include <linux/sched/hotplug.h>
#include <asm/irq.h>
#include <asm/cpu_ops.h>
#include <asm/numa.h>
#include <asm/smp.h>

bool cpu_has_hotplug(unsigned int cpu)
{
        if (cpu_ops->cpu_stop)
                return true;

        return false;
}

/*
 * __cpu_disable runs on the processor to be shutdown.
 */
int __cpu_disable(void)
{
        unsigned int cpu = smp_processor_id();

        if (!cpu_ops->cpu_stop)
                return -EOPNOTSUPP;

        remove_cpu_topology(cpu);
        numa_remove_cpu(cpu);
        set_cpu_online(cpu, false);
        riscv_ipi_disable();
        irq_migrate_all_off_this_cpu();

        return 0;
}

#ifdef CONFIG_HOTPLUG_CPU
/*
 * Called on the thread which is asking for a CPU to be shutdown, if the
 * CPU reported dead to the hotplug core.
 */
void arch_cpuhp_cleanup_dead_cpu(unsigned int cpu)
{
        int ret = 0;

        pr_notice("CPU%u: off\n", cpu);

        clear_tasks_mm_cpumask(cpu);
        /* Verify from the firmware if the cpu is really stopped*/
        if (cpu_ops->cpu_is_stopped)
                ret = cpu_ops->cpu_is_stopped(cpu);
        if (ret)
                pr_warn("CPU%u may not have stopped: %d\n", cpu, ret);
}

/*
 * Called from the idle thread for the CPU which has been shutdown.
 */
void __noreturn arch_cpu_idle_dead(void)
{
        idle_task_exit();

        cpuhp_ap_report_dead();

        cpu_ops->cpu_stop();
        /* It should never reach here */
        BUG();
}
#endif
Linux
