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
  38 static DECLARE_COMPLETION(cpu_running);
  39
  40 void __init smp_prepare_boot_cpu(void)
  41 {
  42 }
  43
  44 void __init smp_prepare_cpus(unsigned int max_cpus)
  45 {
  46         int cpuid;
  47         int ret;
  48         unsigned int curr_cpuid;
  49
  50         init_cpu_topology();
  51
  52         curr_cpuid = smp_processor_id();
  53         store_cpu_topology(curr_cpuid);
  54         numa_store_cpu_info(curr_cpuid);
  55         numa_add_cpu(curr_cpuid);
  56
  57         /* This covers non-smp usecase mandated by "nosmp" option */
  58         if (max_cpus == 0)
  59                 return;
  60
  61         for_each_possible_cpu(cpuid) {
  62                 if (cpuid == curr_cpuid)
  63                         continue;
  64                 if (cpu_ops[cpuid]->cpu_prepare) {
  65                         ret = cpu_ops[cpuid]->cpu_prepare(cpuid);
  66                         if (ret)
  67                                 continue;
  68                 }
  69                 set_cpu_present(cpuid, true);
  70                 numa_store_cpu_info(cpuid);
  71         }
  72 }
  73
  74 void __init setup_smp(void)
  75 {
  76         struct device_node *dn;
  77         unsigned long hart;
  78         bool found_boot_cpu = false;
  79         int cpuid = 1;
  80         int rc;
  81
  82         cpu_set_ops(0);
  83
  84         for_each_of_cpu_node(dn) {
  85                 rc = riscv_of_processor_hartid(dn, &hart);
  86                 if (rc < 0)
  87                         continue;
  88
  89                 if (hart == cpuid_to_hartid_map(0)) {
  90                         BUG_ON(found_boot_cpu);
  91                         found_boot_cpu = 1;
  92                         early_map_cpu_to_node(0, of_node_to_nid(dn));
  93                         continue;
  94                 }
  95                 if (cpuid >= NR_CPUS) {
  96                         pr_warn("Invalid cpuid [%d] for hartid [%lu]\n",
  97                                 cpuid, hart);
  98                         continue;
  99                 }
 100
 101                 cpuid_to_hartid_map(cpuid) = hart;
 102                 early_map_cpu_to_node(cpuid, of_node_to_nid(dn));
 103                 cpuid++;
 104         }
 105
 106         BUG_ON(!found_boot_cpu);
 107
 108         if (cpuid > nr_cpu_ids)
 109                 pr_warn("Total number of cpus [%d] is greater than nr_cpus option value [%d]\n",
 110                         cpuid, nr_cpu_ids);
 111
 112         for (cpuid = 1; cpuid < nr_cpu_ids; cpuid++) {
 113                 if (cpuid_to_hartid_map(cpuid) != INVALID_HARTID) {
 114                         cpu_set_ops(cpuid);
 115                         set_cpu_possible(cpuid, true);
 116                 }
 117         }
 118 }
 119
 120 static int start_secondary_cpu(int cpu, struct task_struct *tidle)
 121 {
 122         if (cpu_ops[cpu]->cpu_start)
 123                 return cpu_ops[cpu]->cpu_start(cpu, tidle);
 124
 125         return -EOPNOTSUPP;
 126 }
 127
 128 int __cpu_up(unsigned int cpu, struct task_struct *tidle)
 129 {
 130         int ret = 0;
 131         tidle->thread_info.cpu = cpu;
 132
 133         ret = start_secondary_cpu(cpu, tidle);
 134         if (!ret) {
 135                 wait_for_completion_timeout(&cpu_running,
 136                                             msecs_to_jiffies(1000));
 137
 138                 if (!cpu_online(cpu)) {
 139                         pr_crit("CPU%u: failed to come online\n", cpu);
 140                         ret = -EIO;
 141                 }
 142         } else {
 143                 pr_crit("CPU%u: failed to start\n", cpu);
 144         }
 145
 146         return ret;
 147 }
 148
 149 void __init smp_cpus_done(unsigned int max_cpus)
 150 {
 151 }
 152
 153 /*
 154  * C entry point for a secondary processor.
 155  */
 156 asmlinkage __visible void smp_callin(void)
 157 {
 158         struct mm_struct *mm = &init_mm;
 159         unsigned int curr_cpuid = smp_processor_id();
 160
 161         riscv_clear_ipi();
 162
 163         /* All kernel threads share the same mm context.  */
 164         mmgrab(mm);
 165         current->active_mm = mm;
 166
 167         store_cpu_topology(curr_cpuid);
 168         notify_cpu_starting(curr_cpuid);
 169         numa_add_cpu(curr_cpuid);
 170         set_cpu_online(curr_cpuid, 1);
 171
 172         /*
 173          * Remote TLB flushes are ignored while the CPU is offline, so emit
 174          * a local TLB flush right now just in case.
 175          */
 176         local_flush_tlb_all();
 177         complete(&cpu_running);
 178         /*
 179          * Disable preemption before enabling interrupts, so we don't try to
 180          * schedule a CPU that hasn't actually started yet.
 181          */
 182         local_irq_enable();
 183         cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
 184 }