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/clint.h> 28 #include <asm/cpu_ops.h> 29 #include <asm/irq.h> 30 #include <asm/mmu_context.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 50 /* This covers non-smp usecase mandated by "nosmp" option */ 51 if (max_cpus == 0) 52 return; 53 54 for_each_possible_cpu(cpuid) { 55 if (cpuid == smp_processor_id()) 56 continue; 57 if (cpu_ops[cpuid]->cpu_prepare) { 58 ret = cpu_ops[cpuid]->cpu_prepare(cpuid); 59 if (ret) 60 continue; 61 } 62 set_cpu_present(cpuid, true); 63 } 64 } 65 66 void __init setup_smp(void) 67 { 68 struct device_node *dn; 69 int hart; 70 bool found_boot_cpu = false; 71 int cpuid = 1; 72 73 cpu_set_ops(0); 74 75 for_each_of_cpu_node(dn) { 76 hart = riscv_of_processor_hartid(dn); 77 if (hart < 0) 78 continue; 79 80 if (hart == cpuid_to_hartid_map(0)) { 81 BUG_ON(found_boot_cpu); 82 found_boot_cpu = 1; 83 continue; 84 } 85 if (cpuid >= NR_CPUS) { 86 pr_warn("Invalid cpuid [%d] for hartid [%d]\n", 87 cpuid, hart); 88 break; 89 } 90 91 cpuid_to_hartid_map(cpuid) = hart; 92 cpuid++; 93 } 94 95 BUG_ON(!found_boot_cpu); 96 97 if (cpuid > nr_cpu_ids) 98 pr_warn("Total number of cpus [%d] is greater than nr_cpus option value [%d]\n", 99 cpuid, nr_cpu_ids); 100 101 for (cpuid = 1; cpuid < nr_cpu_ids; cpuid++) { 102 if (cpuid_to_hartid_map(cpuid) != INVALID_HARTID) { 103 cpu_set_ops(cpuid); 104 set_cpu_possible(cpuid, true); 105 } 106 } 107 } 108 109 static int start_secondary_cpu(int cpu, struct task_struct *tidle) 110 { 111 if (cpu_ops[cpu]->cpu_start) 112 return cpu_ops[cpu]->cpu_start(cpu, tidle); 113 114 return -EOPNOTSUPP; 115 } 116 117 int __cpu_up(unsigned int cpu, struct task_struct *tidle) 118 { 119 int ret = 0; 120 tidle->thread_info.cpu = cpu; 121 122 ret = start_secondary_cpu(cpu, tidle); 123 if (!ret) { 124 wait_for_completion_timeout(&cpu_running, 125 msecs_to_jiffies(1000)); 126 127 if (!cpu_online(cpu)) { 128 pr_crit("CPU%u: failed to come online\n", cpu); 129 ret = -EIO; 130 } 131 } else { 132 pr_crit("CPU%u: failed to start\n", cpu); 133 } 134 135 return ret; 136 } 137 138 void __init smp_cpus_done(unsigned int max_cpus) 139 { 140 } 141 142 /* 143 * C entry point for a secondary processor. 144 */ 145 asmlinkage __visible void smp_callin(void) 146 { 147 struct mm_struct *mm = &init_mm; 148 unsigned int curr_cpuid = smp_processor_id(); 149 150 if (!IS_ENABLED(CONFIG_RISCV_SBI)) 151 clint_clear_ipi(cpuid_to_hartid_map(smp_processor_id())); 152 153 /* All kernel threads share the same mm context. */ 154 mmgrab(mm); 155 current->active_mm = mm; 156 157 notify_cpu_starting(curr_cpuid); 158 update_siblings_masks(curr_cpuid); 159 set_cpu_online(curr_cpuid, 1); 160 161 /* 162 * Remote TLB flushes are ignored while the CPU is offline, so emit 163 * a local TLB flush right now just in case. 164 */ 165 local_flush_tlb_all(); 166 complete(&cpu_running); 167 /* 168 * Disable preemption before enabling interrupts, so we don't try to 169 * schedule a CPU that hasn't actually started yet. 170 */ 171 preempt_disable(); 172 local_irq_enable(); 173 cpu_startup_entry(CPUHP_AP_ONLINE_IDLE); 174 } 175