cpu-hotplug.c

 1// SPDX-License-Identifier: GPL-2.0
 2/*
 3 * Copyright (C) 2020 Western Digital Corporation or its affiliates.
 4 */
 5
 6#include <linux/kernel.h>
 7#include <linux/mm.h>
 8#include <linux/sched.h>
 9#include <linux/err.h>
10#include <linux/irq.h>
11#include <linux/cpuhotplug.h>
12#include <linux/cpu.h>
13#include <linux/sched/hotplug.h>
14#include <asm/irq.h>
15#include <asm/cpu_ops.h>
16#include <asm/numa.h>
17#include <asm/smp.h>
18
19bool cpu_has_hotplug(unsigned int cpu)
20{
21	if (cpu_ops->cpu_stop)
22		return true;
23
24	return false;
25}
26
27/*
28 * __cpu_disable runs on the processor to be shutdown.
29 */
30int __cpu_disable(void)
31{
32	unsigned int cpu = smp_processor_id();
33
34	if (!cpu_ops->cpu_stop)
35		return -EOPNOTSUPP;
36
37	remove_cpu_topology(cpu);
38	numa_remove_cpu(cpu);
39	set_cpu_online(cpu, false);
40	riscv_ipi_disable();
41	irq_migrate_all_off_this_cpu();
42
43	return 0;
44}
45
46#ifdef CONFIG_HOTPLUG_CPU
47/*
48 * Called on the thread which is asking for a CPU to be shutdown, if the
49 * CPU reported dead to the hotplug core.
50 */
51void arch_cpuhp_cleanup_dead_cpu(unsigned int cpu)
52{
53	int ret = 0;
54
55	pr_notice("CPU%u: off\n", cpu);
56
57	clear_tasks_mm_cpumask(cpu);
58	/* Verify from the firmware if the cpu is really stopped*/
59	if (cpu_ops->cpu_is_stopped)
60		ret = cpu_ops->cpu_is_stopped(cpu);
61	if (ret)
62		pr_warn("CPU%u may not have stopped: %d\n", cpu, ret);
63}
64
65/*
66 * Called from the idle thread for the CPU which has been shutdown.
67 */
68void __noreturn arch_cpu_idle_dead(void)
69{
70	idle_task_exit();
71
72	cpuhp_ap_report_dead();
73
74	cpu_ops->cpu_stop();
75	/* It should never reach here */
76	BUG();
77}
78#endif