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 } 185