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