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/tlbflush.h>
31 #include <asm/sections.h>
32 #include <asm/sbi.h>
33 #include <asm/smp.h>
34
35 #include "head.h"
36
37 static DECLARE_COMPLETION(cpu_running);
38
smp_prepare_boot_cpu(void)39 void __init smp_prepare_boot_cpu(void)
40 {
41 init_cpu_topology();
42 }
43
smp_prepare_cpus(unsigned int max_cpus)44 void __init smp_prepare_cpus(unsigned int max_cpus)
45 {
46 int cpuid;
47 int ret;
48
49 store_cpu_topology(smp_processor_id());
50
51 /* This covers non-smp usecase mandated by "nosmp" option */
52 if (max_cpus == 0)
53 return;
54
55 for_each_possible_cpu(cpuid) {
56 if (cpuid == smp_processor_id())
57 continue;
58 if (cpu_ops[cpuid]->cpu_prepare) {
59 ret = cpu_ops[cpuid]->cpu_prepare(cpuid);
60 if (ret)
61 continue;
62 }
63 set_cpu_present(cpuid, true);
64 }
65 }
66
setup_smp(void)67 void __init setup_smp(void)
68 {
69 struct device_node *dn;
70 int hart;
71 bool found_boot_cpu = false;
72 int cpuid = 1;
73
74 cpu_set_ops(0);
75
76 for_each_of_cpu_node(dn) {
77 hart = riscv_of_processor_hartid(dn);
78 if (hart < 0)
79 continue;
80
81 if (hart == cpuid_to_hartid_map(0)) {
82 BUG_ON(found_boot_cpu);
83 found_boot_cpu = 1;
84 continue;
85 }
86 if (cpuid >= NR_CPUS) {
87 pr_warn("Invalid cpuid [%d] for hartid [%d]\n",
88 cpuid, hart);
89 break;
90 }
91
92 cpuid_to_hartid_map(cpuid) = hart;
93 cpuid++;
94 }
95
96 BUG_ON(!found_boot_cpu);
97
98 if (cpuid > nr_cpu_ids)
99 pr_warn("Total number of cpus [%d] is greater than nr_cpus option value [%d]\n",
100 cpuid, nr_cpu_ids);
101
102 for (cpuid = 1; cpuid < nr_cpu_ids; cpuid++) {
103 if (cpuid_to_hartid_map(cpuid) != INVALID_HARTID) {
104 cpu_set_ops(cpuid);
105 set_cpu_possible(cpuid, true);
106 }
107 }
108 }
109
start_secondary_cpu(int cpu,struct task_struct * tidle)110 static int start_secondary_cpu(int cpu, struct task_struct *tidle)
111 {
112 if (cpu_ops[cpu]->cpu_start)
113 return cpu_ops[cpu]->cpu_start(cpu, tidle);
114
115 return -EOPNOTSUPP;
116 }
117
__cpu_up(unsigned int cpu,struct task_struct * tidle)118 int __cpu_up(unsigned int cpu, struct task_struct *tidle)
119 {
120 int ret = 0;
121 tidle->thread_info.cpu = cpu;
122
123 ret = start_secondary_cpu(cpu, tidle);
124 if (!ret) {
125 wait_for_completion_timeout(&cpu_running,
126 msecs_to_jiffies(1000));
127
128 if (!cpu_online(cpu)) {
129 pr_crit("CPU%u: failed to come online\n", cpu);
130 ret = -EIO;
131 }
132 } else {
133 pr_crit("CPU%u: failed to start\n", cpu);
134 }
135
136 return ret;
137 }
138
smp_cpus_done(unsigned int max_cpus)139 void __init smp_cpus_done(unsigned int max_cpus)
140 {
141 }
142
143 /*
144 * C entry point for a secondary processor.
145 */
smp_callin(void)146 asmlinkage __visible void smp_callin(void)
147 {
148 struct mm_struct *mm = &init_mm;
149 unsigned int curr_cpuid = smp_processor_id();
150
151 riscv_clear_ipi();
152
153 /* All kernel threads share the same mm context. */
154 mmgrab(mm);
155 current->active_mm = mm;
156
157 store_cpu_topology(curr_cpuid);
158 notify_cpu_starting(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 local_irq_enable();
172 cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
173 }
174