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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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f1e58583b9
This patch enable support for cpu hotplug in RISC-V. It uses SBI HSM extension to online/offline any hart. As a result, the harts are returned to firmware once they are offline. If the harts are brought online afterwards, they re-enter Linux kernel as if a secondary hart booted for the first time. All booting requirements are honored during this process. Tested both on QEMU and HighFive Unleashed board with. Test result follows. --------------------------------------------------- Offline cpu 2 --------------------------------------------------- $ echo 0 > /sys/devices/system/cpu/cpu2/online [ 32.828684] CPU2: off $ cat /proc/cpuinfo processor : 0 hart : 0 isa : rv64imafdcsu mmu : sv48 processor : 1 hart : 1 isa : rv64imafdcsu mmu : sv48 processor : 3 hart : 3 isa : rv64imafdcsu mmu : sv48 processor : 4 hart : 4 isa : rv64imafdcsu mmu : sv48 processor : 5 hart : 5 isa : rv64imafdcsu mmu : sv48 processor : 6 hart : 6 isa : rv64imafdcsu mmu : sv48 processor : 7 hart : 7 isa : rv64imafdcsu mmu : sv48 --------------------------------------------------- online cpu 2 --------------------------------------------------- $ echo 1 > /sys/devices/system/cpu/cpu2/online $ cat /proc/cpuinfo processor : 0 hart : 0 isa : rv64imafdcsu mmu : sv48 processor : 1 hart : 1 isa : rv64imafdcsu mmu : sv48 processor : 2 hart : 2 isa : rv64imafdcsu mmu : sv48 processor : 3 hart : 3 isa : rv64imafdcsu mmu : sv48 processor : 4 hart : 4 isa : rv64imafdcsu mmu : sv48 processor : 5 hart : 5 isa : rv64imafdcsu mmu : sv48 processor : 6 hart : 6 isa : rv64imafdcsu mmu : sv48 processor : 7 hart : 7 isa : rv64imafdcsu mmu : sv48 Signed-off-by: Atish Patra <atish.patra@wdc.com> Reviewed-by: Anup Patel <anup@brainfault.org>
87 lines
1.6 KiB
C
87 lines
1.6 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 2020 Western Digital Corporation or its affiliates.
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*/
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#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <linux/sched.h>
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#include <linux/err.h>
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#include <linux/irq.h>
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#include <linux/cpu.h>
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#include <linux/sched/hotplug.h>
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#include <asm/irq.h>
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#include <asm/cpu_ops.h>
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#include <asm/sbi.h>
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void cpu_stop(void);
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void arch_cpu_idle_dead(void)
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{
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cpu_stop();
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}
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bool cpu_has_hotplug(unsigned int cpu)
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{
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if (cpu_ops[cpu]->cpu_stop)
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return true;
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return false;
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}
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/*
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* __cpu_disable runs on the processor to be shutdown.
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*/
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int __cpu_disable(void)
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{
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int ret = 0;
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unsigned int cpu = smp_processor_id();
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if (!cpu_ops[cpu] || !cpu_ops[cpu]->cpu_stop)
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return -EOPNOTSUPP;
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if (cpu_ops[cpu]->cpu_disable)
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ret = cpu_ops[cpu]->cpu_disable(cpu);
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if (ret)
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return ret;
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remove_cpu_topology(cpu);
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set_cpu_online(cpu, false);
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irq_migrate_all_off_this_cpu();
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return ret;
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}
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/*
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* Called on the thread which is asking for a CPU to be shutdown.
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*/
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void __cpu_die(unsigned int cpu)
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{
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int ret = 0;
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if (!cpu_wait_death(cpu, 5)) {
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pr_err("CPU %u: didn't die\n", cpu);
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return;
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}
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pr_notice("CPU%u: off\n", cpu);
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/* Verify from the firmware if the cpu is really stopped*/
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if (cpu_ops[cpu]->cpu_is_stopped)
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ret = cpu_ops[cpu]->cpu_is_stopped(cpu);
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if (ret)
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pr_warn("CPU%d may not have stopped: %d\n", cpu, ret);
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}
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/*
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* Called from the idle thread for the CPU which has been shutdown.
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*/
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void cpu_stop(void)
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{
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idle_task_exit();
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(void)cpu_report_death();
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cpu_ops[smp_processor_id()]->cpu_stop();
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/* It should never reach here */
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BUG();
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}
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