1 // SPDX-License-Identifier: GPL-2.0-only
3 * SMP initialisation and IPI support
4 * Based on arch/arm64/kernel/smp.c
6 * Copyright (C) 2012 ARM Ltd.
7 * Copyright (C) 2015 Regents of the University of California
8 * Copyright (C) 2017 SiFive
11 #include <linux/arch_topology.h>
12 #include <linux/module.h>
13 #include <linux/init.h>
14 #include <linux/kernel.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>
25 #include <linux/sched/task_stack.h>
26 #include <linux/sched/mm.h>
27 #include <asm/cpu_ops.h>
29 #include <asm/mmu_context.h>
30 #include <asm/tlbflush.h>
31 #include <asm/sections.h>
37 static DECLARE_COMPLETION(cpu_running);
39 void __init smp_prepare_boot_cpu(void)
44 void __init smp_prepare_cpus(unsigned int max_cpus)
49 /* This covers non-smp usecase mandated by "nosmp" option */
53 for_each_possible_cpu(cpuid) {
54 if (cpuid == smp_processor_id())
56 if (cpu_ops[cpuid]->cpu_prepare) {
57 ret = cpu_ops[cpuid]->cpu_prepare(cpuid);
61 set_cpu_present(cpuid, true);
65 void __init setup_smp(void)
67 struct device_node *dn;
69 bool found_boot_cpu = false;
74 for_each_of_cpu_node(dn) {
75 hart = riscv_of_processor_hartid(dn);
79 if (hart == cpuid_to_hartid_map(0)) {
80 BUG_ON(found_boot_cpu);
84 if (cpuid >= NR_CPUS) {
85 pr_warn("Invalid cpuid [%d] for hartid [%d]\n",
90 cpuid_to_hartid_map(cpuid) = hart;
94 BUG_ON(!found_boot_cpu);
96 if (cpuid > nr_cpu_ids)
97 pr_warn("Total number of cpus [%d] is greater than nr_cpus option value [%d]\n",
100 for (cpuid = 1; cpuid < nr_cpu_ids; cpuid++) {
101 if (cpuid_to_hartid_map(cpuid) != INVALID_HARTID) {
103 set_cpu_possible(cpuid, true);
108 static int start_secondary_cpu(int cpu, struct task_struct *tidle)
110 if (cpu_ops[cpu]->cpu_start)
111 return cpu_ops[cpu]->cpu_start(cpu, tidle);
116 int __cpu_up(unsigned int cpu, struct task_struct *tidle)
119 tidle->thread_info.cpu = cpu;
121 ret = start_secondary_cpu(cpu, tidle);
123 wait_for_completion_timeout(&cpu_running,
124 msecs_to_jiffies(1000));
126 if (!cpu_online(cpu)) {
127 pr_crit("CPU%u: failed to come online\n", cpu);
131 pr_crit("CPU%u: failed to start\n", cpu);
137 void __init smp_cpus_done(unsigned int max_cpus)
142 * C entry point for a secondary processor.
144 asmlinkage __visible void smp_callin(void)
146 struct mm_struct *mm = &init_mm;
147 unsigned int curr_cpuid = smp_processor_id();
151 /* All kernel threads share the same mm context. */
153 current->active_mm = mm;
155 notify_cpu_starting(curr_cpuid);
156 update_siblings_masks(curr_cpuid);
157 set_cpu_online(curr_cpuid, 1);
160 * Remote TLB flushes are ignored while the CPU is offline, so emit
161 * a local TLB flush right now just in case.
163 local_flush_tlb_all();
164 complete(&cpu_running);
166 * Disable preemption before enabling interrupts, so we don't try to
167 * schedule a CPU that hasn't actually started yet.
171 cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);