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 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
setup_smp(void)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
start_secondary_cpu(int cpu,struct task_struct * tidle)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
__cpu_up(unsigned int cpu,struct task_struct * tidle)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
smp_cpus_done(unsigned int max_cpus)150 void __init smp_cpus_done(unsigned int max_cpus)
151 {
152 }
153
154 /*
155 * C entry point for a secondary processor.
156 */
smp_callin(void)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