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/tlbflush.h>
  31 #include <asm/sections.h>
  32 #include <asm/sbi.h>
  33 #include <asm/smp.h>
  34
  35 #include "head.h"
  36
  37 static DECLARE_COMPLETION(cpu_running);
  38
  39 void __init smp_prepare_boot_cpu(void)
  40 {
  41         init_cpu_topology();
  42 }
  43
  44 void __init smp_prepare_cpus(unsigned int max_cpus)
  45 {
  46         int cpuid;
  47         int ret;
  48
  49         /* This covers non-smp usecase mandated by "nosmp" option */
  50         if (max_cpus == 0)
  51                 return;
  52
  53         for_each_possible_cpu(cpuid) {
  54                 if (cpuid == smp_processor_id())
  55                         continue;
  56                 if (cpu_ops[cpuid]->cpu_prepare) {
  57                         ret = cpu_ops[cpuid]->cpu_prepare(cpuid);
  58                         if (ret)
  59                                 continue;
  60                 }
  61                 set_cpu_present(cpuid, true);
  62         }
  63 }
  64
  65 void __init setup_smp(void)
  66 {
  67         struct device_node *dn;
  68         int hart;
  69         bool found_boot_cpu = false;
  70         int cpuid = 1;
  71
  72         cpu_set_ops(0);
  73
  74         for_each_of_cpu_node(dn) {
  75                 hart = riscv_of_processor_hartid(dn);
  76                 if (hart < 0)
  77                         continue;
  78
  79                 if (hart == cpuid_to_hartid_map(0)) {
  80                         BUG_ON(found_boot_cpu);
  81                         found_boot_cpu = 1;
  82                         continue;
  83                 }
  84                 if (cpuid >= NR_CPUS) {
  85                         pr_warn("Invalid cpuid [%d] for hartid [%d]\n",
  86                                 cpuid, hart);
  87                         break;
  88                 }
  89
  90                 cpuid_to_hartid_map(cpuid) = hart;
  91                 cpuid++;
  92         }
  93
  94         BUG_ON(!found_boot_cpu);
  95
  96         if (cpuid > nr_cpu_ids)
  97                 pr_warn("Total number of cpus [%d] is greater than nr_cpus option value [%d]\n",
  98                         cpuid, nr_cpu_ids);
  99
 100         for (cpuid = 1; cpuid < nr_cpu_ids; cpuid++) {
 101                 if (cpuid_to_hartid_map(cpuid) != INVALID_HARTID) {
 102                         cpu_set_ops(cpuid);
 103                         set_cpu_possible(cpuid, true);
 104                 }
 105         }
 106 }
 107
 108 static int start_secondary_cpu(int cpu, struct task_struct *tidle)
 109 {
 110         if (cpu_ops[cpu]->cpu_start)
 111                 return cpu_ops[cpu]->cpu_start(cpu, tidle);
 112
 113         return -EOPNOTSUPP;
 114 }
 115
 116 int __cpu_up(unsigned int cpu, struct task_struct *tidle)
 117 {
 118         int ret = 0;
 119         tidle->thread_info.cpu = cpu;
 120
 121         ret = start_secondary_cpu(cpu, tidle);
 122         if (!ret) {
 123                 wait_for_completion_timeout(&cpu_running,
 124                                             msecs_to_jiffies(1000));
 125
 126                 if (!cpu_online(cpu)) {
 127                         pr_crit("CPU%u: failed to come online\n", cpu);
 128                         ret = -EIO;
 129                 }
 130         } else {
 131                 pr_crit("CPU%u: failed to start\n", cpu);
 132         }
 133
 134         return ret;
 135 }
 136
 137 void __init smp_cpus_done(unsigned int max_cpus)
 138 {
 139 }
 140
 141 /*
 142  * C entry point for a secondary processor.
 143  */
 144 asmlinkage __visible void smp_callin(void)
 145 {
 146         struct mm_struct *mm = &init_mm;
 147         unsigned int curr_cpuid = smp_processor_id();
 148
 149         riscv_clear_ipi();
 150
 151         /* All kernel threads share the same mm context.  */
 152         mmgrab(mm);
 153         current->active_mm = mm;
 154
 155         notify_cpu_starting(curr_cpuid);
 156         update_siblings_masks(curr_cpuid);
 157         set_cpu_online(curr_cpuid, 1);
 158
 159         /*
 160          * Remote TLB flushes are ignored while the CPU is offline, so emit
 161          * a local TLB flush right now just in case.
 162          */
 163         local_flush_tlb_all();
 164         complete(&cpu_running);
 165         /*
 166          * Disable preemption before enabling interrupts, so we don't try to
 167          * schedule a CPU that hasn't actually started yet.
 168          */
 169         preempt_disable();
 170         local_irq_enable();
 171         cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
 172 }