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 } 173