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/acpi.h>
12#include <linux/arch_topology.h>
13#include <linux/module.h>
14#include <linux/init.h>
15#include <linux/kernel.h>
16#include <linux/mm.h>
17#include <linux/sched.h>
18#include <linux/kernel_stat.h>
19#include <linux/notifier.h>
20#include <linux/cpu.h>
21#include <linux/percpu.h>
22#include <linux/delay.h>
23#include <linux/err.h>
24#include <linux/irq.h>
25#include <linux/of.h>
26#include <linux/sched/task_stack.h>
27#include <linux/sched/mm.h>
28
29#include <asm/cacheflush.h>
30#include <asm/cpu_ops.h>
31#include <asm/irq.h>
32#include <asm/mmu_context.h>
33#include <asm/numa.h>
34#include <asm/tlbflush.h>
35#include <asm/sections.h>
36#include <asm/smp.h>
37#include <uapi/asm/hwcap.h>
38#include <asm/vector.h>
39
40#include "head.h"
41
42static DECLARE_COMPLETION(cpu_running);
43
44void __init smp_prepare_cpus(unsigned int max_cpus)
45{
46 int cpuid;
47 unsigned int curr_cpuid;
48
49 init_cpu_topology();
50
51 curr_cpuid = smp_processor_id();
52 store_cpu_topology(curr_cpuid);
53 numa_store_cpu_info(curr_cpuid);
54 numa_add_cpu(cpu: curr_cpuid);
55
56 /* This covers non-smp usecase mandated by "nosmp" option */
57 if (max_cpus == 0)
58 return;
59
60 for_each_possible_cpu(cpuid) {
61 if (cpuid == curr_cpuid)
62 continue;
63 set_cpu_present(cpuid, true);
64 numa_store_cpu_info(cpuid);
65 }
66}
67
68#ifdef CONFIG_ACPI
69static unsigned int cpu_count = 1;
70
71static int __init acpi_parse_rintc(union acpi_subtable_headers *header, const unsigned long end)
72{
73 unsigned long hart;
74 static bool found_boot_cpu;
75 struct acpi_madt_rintc *processor = (struct acpi_madt_rintc *)header;
76
77 /*
78 * Each RINTC structure in MADT will have a flag. If ACPI_MADT_ENABLED
79 * bit in the flag is not enabled, it means OS should not try to enable
80 * the cpu to which RINTC belongs.
81 */
82 if (!(processor->flags & ACPI_MADT_ENABLED))
83 return 0;
84
85 if (BAD_MADT_ENTRY(processor, end))
86 return -EINVAL;
87
88 acpi_table_print_madt_entry(madt: &header->common);
89
90 hart = processor->hart_id;
91 if (hart == INVALID_HARTID) {
92 pr_warn("Invalid hartid\n");
93 return 0;
94 }
95
96 if (hart == cpuid_to_hartid_map(0)) {
97 BUG_ON(found_boot_cpu);
98 found_boot_cpu = true;
99 return 0;
100 }
101
102 if (cpu_count >= NR_CPUS) {
103 pr_warn("NR_CPUS is too small for the number of ACPI tables.\n");
104 return 0;
105 }
106
107 cpuid_to_hartid_map(cpu_count) = hart;
108 cpu_count++;
109
110 return 0;
111}
112
113static void __init acpi_parse_and_init_cpus(void)
114{
115 acpi_table_parse_madt(id: ACPI_MADT_TYPE_RINTC, handler: acpi_parse_rintc, max_entries: 0);
116}
117#else
118#define acpi_parse_and_init_cpus(...) do { } while (0)
119#endif
120
121static void __init of_parse_and_init_cpus(void)
122{
123 struct device_node *dn;
124 unsigned long hart;
125 bool found_boot_cpu = false;
126 int cpuid = 1;
127 int rc;
128
129 for_each_of_cpu_node(dn) {
130 rc = riscv_early_of_processor_hartid(dn, &hart);
131 if (rc < 0)
132 continue;
133
134 if (hart == cpuid_to_hartid_map(0)) {
135 BUG_ON(found_boot_cpu);
136 found_boot_cpu = 1;
137 early_map_cpu_to_node(0, of_node_to_nid(np: dn));
138 continue;
139 }
140 if (cpuid >= NR_CPUS) {
141 pr_warn("Invalid cpuid [%d] for hartid [%lu]\n",
142 cpuid, hart);
143 continue;
144 }
145
146 cpuid_to_hartid_map(cpuid) = hart;
147 early_map_cpu_to_node(cpuid, of_node_to_nid(np: dn));
148 cpuid++;
149 }
150
151 BUG_ON(!found_boot_cpu);
152
153 if (cpuid > nr_cpu_ids)
154 pr_warn("Total number of cpus [%d] is greater than nr_cpus option value [%d]\n",
155 cpuid, nr_cpu_ids);
156}
157
158void __init setup_smp(void)
159{
160 int cpuid;
161
162 cpu_set_ops();
163
164 if (acpi_disabled)
165 of_parse_and_init_cpus();
166 else
167 acpi_parse_and_init_cpus();
168
169 for (cpuid = 1; cpuid < nr_cpu_ids; cpuid++)
170 if (cpuid_to_hartid_map(cpuid) != INVALID_HARTID)
171 set_cpu_possible(cpuid, true);
172}
173
174static int start_secondary_cpu(int cpu, struct task_struct *tidle)
175{
176 if (cpu_ops->cpu_start)
177 return cpu_ops->cpu_start(cpu, tidle);
178
179 return -EOPNOTSUPP;
180}
181
182int __cpu_up(unsigned int cpu, struct task_struct *tidle)
183{
184 int ret = 0;
185 tidle->thread_info.cpu = cpu;
186
187 ret = start_secondary_cpu(cpu, tidle);
188 if (!ret) {
189 wait_for_completion_timeout(x: &cpu_running,
190 timeout: msecs_to_jiffies(m: 1000));
191
192 if (!cpu_online(cpu)) {
193 pr_crit("CPU%u: failed to come online\n", cpu);
194 ret = -EIO;
195 }
196 } else {
197 pr_crit("CPU%u: failed to start\n", cpu);
198 }
199
200 return ret;
201}
202
203void __init smp_cpus_done(unsigned int max_cpus)
204{
205}
206
207/*
208 * C entry point for a secondary processor.
209 */
210asmlinkage __visible void smp_callin(void)
211{
212 struct mm_struct *mm = &init_mm;
213 unsigned int curr_cpuid = smp_processor_id();
214
215 if (has_vector()) {
216 /*
217 * Return as early as possible so the hart with a mismatching
218 * vlen won't boot.
219 */
220 if (riscv_v_setup_vsize())
221 return;
222 }
223
224 /* All kernel threads share the same mm context. */
225 mmgrab(mm);
226 current->active_mm = mm;
227
228 store_cpu_topology(curr_cpuid);
229 notify_cpu_starting(cpu: curr_cpuid);
230
231 riscv_ipi_enable();
232
233 numa_add_cpu(cpu: curr_cpuid);
234
235 pr_debug("CPU%u: Booted secondary hartid %lu\n", curr_cpuid,
236 cpuid_to_hartid_map(curr_cpuid));
237
238 set_cpu_online(cpu: curr_cpuid, online: true);
239
240 /*
241 * Remote cache and TLB flushes are ignored while the CPU is offline,
242 * so flush them both right now just in case.
243 */
244 local_flush_icache_all();
245 local_flush_tlb_all();
246 complete(&cpu_running);
247 /*
248 * Disable preemption before enabling interrupts, so we don't try to
249 * schedule a CPU that hasn't actually started yet.
250 */
251 local_irq_enable();
252 cpu_startup_entry(state: CPUHP_AP_ONLINE_IDLE);
253}
254

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source code of linux/arch/riscv/kernel/smpboot.c