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