LXR linux/arch/riscv/kernel/smpboot.c

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * SMP initialisation and IPI support
   4 * Based on arch/arm64/kernel/smp.c
   5 *
   6 * Copyright (C) 2012 ARM Ltd.
   7 * Copyright (C) 2015 Regents of the University of California
   8 * Copyright (C) 2017 SiFive
   9 */
  10
  11#include <linux/arch_topology.h>
  12#include <linux/module.h>
  13#include <linux/init.h>
  14#include <linux/kernel.h>
  15#include <linux/mm.h>
  16#include <linux/sched.h>
  17#include <linux/kernel_stat.h>
  18#include <linux/notifier.h>
  19#include <linux/cpu.h>
  20#include <linux/percpu.h>
  21#include <linux/delay.h>
  22#include <linux/err.h>
  23#include <linux/irq.h>
  24#include <linux/of.h>
  25#include <linux/sched/task_stack.h>
  26#include <linux/sched/mm.h>
  27#include <asm/cpu_ops.h>
  28#include <asm/irq.h>
  29#include <asm/mmu_context.h>
  30#include <asm/numa.h>
  31#include <asm/tlbflush.h>
  32#include <asm/sections.h>
  33#include <asm/sbi.h>
  34#include <asm/smp.h>
  35
  36#include "head.h"
  37
  38static DECLARE_COMPLETION(cpu_running);
  39
  40void __init smp_prepare_boot_cpu(void)
  41{
  42        init_cpu_topology();
  43}
  44
  45void __init smp_prepare_cpus(unsigned int max_cpus)
  46{
  47        int cpuid;
  48        int ret;
  49        unsigned int curr_cpuid;
  50
  51        curr_cpuid = smp_processor_id();
  52        numa_store_cpu_info(curr_cpuid);
  53        numa_add_cpu(curr_cpuid);
  54
  55        /* This covers non-smp usecase mandated by "nosmp" option */
  56        if (max_cpus == 0)
  57                return;
  58
  59        for_each_possible_cpu(cpuid) {
  60                if (cpuid == curr_cpuid)
  61                        continue;
  62                if (cpu_ops[cpuid]->cpu_prepare) {
  63                        ret = cpu_ops[cpuid]->cpu_prepare(cpuid);
  64                        if (ret)
  65                                continue;
  66                }
  67                set_cpu_present(cpuid, true);
  68                numa_store_cpu_info(cpuid);
  69        }
  70}
  71
  72void __init setup_smp(void)
  73{
  74        struct device_node *dn;
  75        int hart;
  76        bool found_boot_cpu = false;
  77        int cpuid = 1;
  78
  79        cpu_set_ops(0);
  80
  81        for_each_of_cpu_node(dn) {
  82                hart = riscv_of_processor_hartid(dn);
  83                if (hart < 0)
  84                        continue;
  85
  86                if (hart == cpuid_to_hartid_map(0)) {
  87                        BUG_ON(found_boot_cpu);
  88                        found_boot_cpu = 1;
  89                        early_map_cpu_to_node(0, of_node_to_nid(dn));
  90                        continue;
  91                }
  92                if (cpuid >= NR_CPUS) {
  93                        pr_warn("Invalid cpuid [%d] for hartid [%d]\n",
  94                                cpuid, hart);
  95                        break;
  96                }
  97
  98                cpuid_to_hartid_map(cpuid) = hart;
  99                early_map_cpu_to_node(cpuid, of_node_to_nid(dn));
 100                cpuid++;
 101        }
 102
 103        BUG_ON(!found_boot_cpu);
 104
 105        if (cpuid > nr_cpu_ids)
 106                pr_warn("Total number of cpus [%d] is greater than nr_cpus option value [%d]\n",
 107                        cpuid, nr_cpu_ids);
 108
 109        for (cpuid = 1; cpuid < nr_cpu_ids; cpuid++) {
 110                if (cpuid_to_hartid_map(cpuid) != INVALID_HARTID) {
 111                        cpu_set_ops(cpuid);
 112                        set_cpu_possible(cpuid, true);
 113                }
 114        }
 115}
 116
 117static int start_secondary_cpu(int cpu, struct task_struct *tidle)
 118{
 119        if (cpu_ops[cpu]->cpu_start)
 120                return cpu_ops[cpu]->cpu_start(cpu, tidle);
 121
 122        return -EOPNOTSUPP;
 123}
 124
 125int __cpu_up(unsigned int cpu, struct task_struct *tidle)
 126{
 127        int ret = 0;
 128        tidle->thread_info.cpu = cpu;
 129
 130        ret = start_secondary_cpu(cpu, tidle);
 131        if (!ret) {
 132                wait_for_completion_timeout(&cpu_running,
 133                                            msecs_to_jiffies(1000));
 134
 135                if (!cpu_online(cpu)) {
 136                        pr_crit("CPU%u: failed to come online\n", cpu);
 137                        ret = -EIO;
 138                }
 139        } else {
 140                pr_crit("CPU%u: failed to start\n", cpu);
 141        }
 142
 143        return ret;
 144}
 145
 146void __init smp_cpus_done(unsigned int max_cpus)
 147{
 148}
 149
 150/*
 151 * C entry point for a secondary processor.
 152 */
 153asmlinkage __visible void smp_callin(void)
 154{
 155        struct mm_struct *mm = &init_mm;
 156        unsigned int curr_cpuid = smp_processor_id();
 157
 158        riscv_clear_ipi();
 159
 160        /* All kernel threads share the same mm context.  */
 161        mmgrab(mm);
 162        current->active_mm = mm;
 163
 164        notify_cpu_starting(curr_cpuid);
 165        numa_add_cpu(curr_cpuid);
 166        update_siblings_masks(curr_cpuid);
 167        set_cpu_online(curr_cpuid, 1);
 168
 169        /*
 170         * Remote TLB flushes are ignored while the CPU is offline, so emit
 171         * a local TLB flush right now just in case.
 172         */
 173        local_flush_tlb_all();
 174        complete(&cpu_running);
 175        /*
 176         * Disable preemption before enabling interrupts, so we don't try to
 177         * schedule a CPU that hasn't actually started yet.
 178         */
 179        preempt_disable();
 180        local_irq_enable();
 181        cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
 182}
 183