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 #include <asm/alternative.h> 36 37 #include "head.h" 38 39 static DECLARE_COMPLETION(cpu_running); 40 41 void __init smp_prepare_boot_cpu(void) 42 { 43 init_cpu_topology(); 44 #ifdef CONFIG_RISCV_ERRATA_ALTERNATIVE 45 apply_boot_alternatives(); 46 #endif 47 } 48 49 void __init smp_prepare_cpus(unsigned int max_cpus) 50 { 51 int cpuid; 52 int ret; 53 unsigned int curr_cpuid; 54 55 curr_cpuid = smp_processor_id(); 56 numa_store_cpu_info(curr_cpuid); 57 numa_add_cpu(curr_cpuid); 58 59 /* This covers non-smp usecase mandated by "nosmp" option */ 60 if (max_cpus == 0) 61 return; 62 63 for_each_possible_cpu(cpuid) { 64 if (cpuid == curr_cpuid) 65 continue; 66 if (cpu_ops[cpuid]->cpu_prepare) { 67 ret = cpu_ops[cpuid]->cpu_prepare(cpuid); 68 if (ret) 69 continue; 70 } 71 set_cpu_present(cpuid, true); 72 numa_store_cpu_info(cpuid); 73 } 74 } 75 76 void __init setup_smp(void) 77 { 78 struct device_node *dn; 79 int hart; 80 bool found_boot_cpu = false; 81 int cpuid = 1; 82 83 cpu_set_ops(0); 84 85 for_each_of_cpu_node(dn) { 86 hart = riscv_of_processor_hartid(dn); 87 if (hart < 0) 88 continue; 89 90 if (hart == cpuid_to_hartid_map(0)) { 91 BUG_ON(found_boot_cpu); 92 found_boot_cpu = 1; 93 early_map_cpu_to_node(0, of_node_to_nid(dn)); 94 continue; 95 } 96 if (cpuid >= NR_CPUS) { 97 pr_warn("Invalid cpuid [%d] for hartid [%d]\n", 98 cpuid, hart); 99 break; 100 } 101 102 cpuid_to_hartid_map(cpuid) = hart; 103 early_map_cpu_to_node(cpuid, of_node_to_nid(dn)); 104 cpuid++; 105 } 106 107 BUG_ON(!found_boot_cpu); 108 109 if (cpuid > nr_cpu_ids) 110 pr_warn("Total number of cpus [%d] is greater than nr_cpus option value [%d]\n", 111 cpuid, nr_cpu_ids); 112 113 for (cpuid = 1; cpuid < nr_cpu_ids; cpuid++) { 114 if (cpuid_to_hartid_map(cpuid) != INVALID_HARTID) { 115 cpu_set_ops(cpuid); 116 set_cpu_possible(cpuid, true); 117 } 118 } 119 } 120 121 static int start_secondary_cpu(int cpu, struct task_struct *tidle) 122 { 123 if (cpu_ops[cpu]->cpu_start) 124 return cpu_ops[cpu]->cpu_start(cpu, tidle); 125 126 return -EOPNOTSUPP; 127 } 128 129 int __cpu_up(unsigned int cpu, struct task_struct *tidle) 130 { 131 int ret = 0; 132 tidle->thread_info.cpu = cpu; 133 134 ret = start_secondary_cpu(cpu, tidle); 135 if (!ret) { 136 wait_for_completion_timeout(&cpu_running, 137 msecs_to_jiffies(1000)); 138 139 if (!cpu_online(cpu)) { 140 pr_crit("CPU%u: failed to come online\n", cpu); 141 ret = -EIO; 142 } 143 } else { 144 pr_crit("CPU%u: failed to start\n", cpu); 145 } 146 147 return ret; 148 } 149 150 void __init smp_cpus_done(unsigned int max_cpus) 151 { 152 } 153 154 /* 155 * C entry point for a secondary processor. 156 */ 157 asmlinkage __visible void smp_callin(void) 158 { 159 struct mm_struct *mm = &init_mm; 160 unsigned int curr_cpuid = smp_processor_id(); 161 162 riscv_clear_ipi(); 163 164 /* All kernel threads share the same mm context. */ 165 mmgrab(mm); 166 current->active_mm = mm; 167 168 notify_cpu_starting(curr_cpuid); 169 numa_add_cpu(curr_cpuid); 170 update_siblings_masks(curr_cpuid); 171 set_cpu_online(curr_cpuid, 1); 172 173 /* 174 * Remote TLB flushes are ignored while the CPU is offline, so emit 175 * a local TLB flush right now just in case. 176 */ 177 local_flush_tlb_all(); 178 complete(&cpu_running); 179 /* 180 * Disable preemption before enabling interrupts, so we don't try to 181 * schedule a CPU that hasn't actually started yet. 182 */ 183 preempt_disable(); 184 local_irq_enable(); 185 cpu_startup_entry(CPUHP_AP_ONLINE_IDLE); 186 } 187