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