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/cpufeature.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(cpu: cpuid, present: 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 early_map_cpu_to_node(0, acpi_numa_get_nid(cpu_count));
100 return 0;
101 }
102
103 if (cpu_count >= NR_CPUS) {
104 pr_warn("NR_CPUS is too small for the number of ACPI tables.\n");
105 return 0;
106 }
107
108 cpuid_to_hartid_map(cpu_count) = hart;
109 early_map_cpu_to_node(cpu_count, acpi_numa_get_nid(cpu_count));
110 cpu_count++;
111
112 return 0;
113}
114
115static void __init acpi_parse_and_init_cpus(void)
116{
117 acpi_table_parse_madt(id: ACPI_MADT_TYPE_RINTC, handler: acpi_parse_rintc, max_entries: 0);
118}
119#else
120#define acpi_parse_and_init_cpus(...) do { } while (0)
121#endif
122
123static void __init of_parse_and_init_cpus(void)
124{
125 struct device_node *dn;
126 unsigned long hart;
127 bool found_boot_cpu = false;
128 int cpuid = 1;
129 int rc;
130
131 for_each_of_cpu_node(dn) {
132 rc = riscv_early_of_processor_hartid(dn, &hart);
133 if (rc < 0)
134 continue;
135
136 if (hart == cpuid_to_hartid_map(0)) {
137 BUG_ON(found_boot_cpu);
138 found_boot_cpu = 1;
139 early_map_cpu_to_node(0, of_node_to_nid(np: dn));
140 continue;
141 }
142 if (cpuid >= NR_CPUS) {
143 pr_warn("Invalid cpuid [%d] for hartid [%lu]\n",
144 cpuid, hart);
145 continue;
146 }
147
148 cpuid_to_hartid_map(cpuid) = hart;
149 early_map_cpu_to_node(cpuid, of_node_to_nid(np: dn));
150 cpuid++;
151 }
152
153 BUG_ON(!found_boot_cpu);
154
155 if (cpuid > nr_cpu_ids)
156 pr_warn("Total number of cpus [%d] is greater than nr_cpus option value [%d]\n",
157 cpuid, nr_cpu_ids);
158}
159
160void __init setup_smp(void)
161{
162 int cpuid;
163
164 cpu_set_ops();
165
166 if (acpi_disabled)
167 of_parse_and_init_cpus();
168 else
169 acpi_parse_and_init_cpus();
170
171 for (cpuid = 1; cpuid < nr_cpu_ids; cpuid++)
172 if (cpuid_to_hartid_map(cpuid) != INVALID_HARTID)
173 set_cpu_possible(cpu: cpuid, possible: true);
174}
175
176static int start_secondary_cpu(int cpu, struct task_struct *tidle)
177{
178 if (cpu_ops->cpu_start)
179 return cpu_ops->cpu_start(cpu, tidle);
180
181 return -EOPNOTSUPP;
182}
183
184int __cpu_up(unsigned int cpu, struct task_struct *tidle)
185{
186 int ret = 0;
187 tidle->thread_info.cpu = cpu;
188
189 ret = start_secondary_cpu(cpu, tidle);
190 if (!ret) {
191 wait_for_completion_timeout(x: &cpu_running,
192 timeout: msecs_to_jiffies(m: 1000));
193
194 if (!cpu_online(cpu)) {
195 pr_crit("CPU%u: failed to come online\n", cpu);
196 ret = -EIO;
197 }
198 } else {
199 pr_crit("CPU%u: failed to start\n", cpu);
200 }
201
202 return ret;
203}
204
205void __init smp_cpus_done(unsigned int max_cpus)
206{
207}
208
209/*
210 * C entry point for a secondary processor.
211 */
212asmlinkage __visible void smp_callin(void)
213{
214 struct mm_struct *mm = &init_mm;
215 unsigned int curr_cpuid = smp_processor_id();
216
217 /* All kernel threads share the same mm context. */
218 mmgrab(mm);
219 current->active_mm = mm;
220
221 store_cpu_topology(curr_cpuid);
222 notify_cpu_starting(cpu: curr_cpuid);
223
224 riscv_ipi_enable();
225
226 numa_add_cpu(cpu: curr_cpuid);
227 set_cpu_online(cpu: curr_cpuid, online: 1);
228
229 if (has_vector()) {
230 if (riscv_v_setup_vsize())
231 elf_hwcap &= ~COMPAT_HWCAP_ISA_V;
232 }
233
234 riscv_user_isa_enable();
235
236 /*
237 * Remote TLB flushes are ignored while the CPU is offline, so emit
238 * a local TLB flush right now just in case.
239 */
240 local_flush_tlb_all();
241 complete(&cpu_running);
242 /*
243 * Disable preemption before enabling interrupts, so we don't try to
244 * schedule a CPU that hasn't actually started yet.
245 */
246 local_irq_enable();
247 cpu_startup_entry(state: CPUHP_AP_ONLINE_IDLE);
248}
249

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