arch/riscv/kernel/smp.c

   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/cpu.h>
  12 #include <linux/clockchips.h>
  13 #include <linux/interrupt.h>
  14 #include <linux/module.h>
  15 #include <linux/kexec.h>
  16 #include <linux/percpu.h>
  17 #include <linux/profile.h>
  18 #include <linux/smp.h>
  19 #include <linux/sched.h>
  20 #include <linux/seq_file.h>
  21 #include <linux/delay.h>
  22 #include <linux/irq.h>
  23 #include <linux/irq_work.h>
  24
  25 #include <asm/tlbflush.h>
  26 #include <asm/cacheflush.h>
  27 #include <asm/cpu_ops.h>
  28
  29 enum ipi_message_type {
  30         IPI_RESCHEDULE,
  31         IPI_CALL_FUNC,
  32         IPI_CPU_STOP,
  33         IPI_CPU_CRASH_STOP,
  34         IPI_IRQ_WORK,
  35         IPI_TIMER,
  36         IPI_MAX
  37 };
  38
  39 unsigned long __cpuid_to_hartid_map[NR_CPUS] __ro_after_init = {
  40         [0 ... NR_CPUS-1] = INVALID_HARTID
  41 };
  42
  43 void __init smp_setup_processor_id(void)
  44 {
  45         cpuid_to_hartid_map(0) = boot_cpu_hartid;
  46 }
  47
  48 static DEFINE_PER_CPU_READ_MOSTLY(int, ipi_dummy_dev);
  49 static int ipi_virq_base __ro_after_init;
  50 static int nr_ipi __ro_after_init = IPI_MAX;
  51 static struct irq_desc *ipi_desc[IPI_MAX] __read_mostly;
  52
  53 int riscv_hartid_to_cpuid(unsigned long hartid)
  54 {
  55         int i;
  56
  57         for (i = 0; i < NR_CPUS; i++)
  58                 if (cpuid_to_hartid_map(i) == hartid)
  59                         return i;
  60
  61         return -ENOENT;
  62 }
  63
  64 bool arch_match_cpu_phys_id(int cpu, u64 phys_id)
  65 {
  66         return phys_id == cpuid_to_hartid_map(cpu);
  67 }
  68
  69 static void ipi_stop(void)
  70 {
  71         set_cpu_online(smp_processor_id(), false);
  72         while (1)
  73                 wait_for_interrupt();
  74 }
  75
  76 #ifdef CONFIG_KEXEC_CORE
  77 static atomic_t waiting_for_crash_ipi = ATOMIC_INIT(0);
  78
  79 static inline void ipi_cpu_crash_stop(unsigned int cpu, struct pt_regs *regs)
  80 {
  81         crash_save_cpu(regs, cpu);
  82
  83         atomic_dec(&waiting_for_crash_ipi);
  84
  85         local_irq_disable();
  86
  87 #ifdef CONFIG_HOTPLUG_CPU
  88         if (cpu_has_hotplug(cpu))
  89                 cpu_ops[cpu]->cpu_stop();
  90 #endif
  91
  92         for(;;)
  93                 wait_for_interrupt();
  94 }
  95 #else
  96 static inline void ipi_cpu_crash_stop(unsigned int cpu, struct pt_regs *regs)
  97 {
  98         unreachable();
  99 }
 100 #endif
 101
 102 static void send_ipi_mask(const struct cpumask *mask, enum ipi_message_type op)
 103 {
 104         __ipi_send_mask(ipi_desc[op], mask);
 105 }
 106
 107 static void send_ipi_single(int cpu, enum ipi_message_type op)
 108 {
 109         __ipi_send_mask(ipi_desc[op], cpumask_of(cpu));
 110 }
 111
 112 #ifdef CONFIG_IRQ_WORK
 113 void arch_irq_work_raise(void)
 114 {
 115         send_ipi_single(smp_processor_id(), IPI_IRQ_WORK);
 116 }
 117 #endif
 118
 119 static irqreturn_t handle_IPI(int irq, void *data)
 120 {
 121         int ipi = irq - ipi_virq_base;
 122
 123         switch (ipi) {
 124         case IPI_RESCHEDULE:
 125                 scheduler_ipi();
 126                 break;
 127         case IPI_CALL_FUNC:
 128                 generic_smp_call_function_interrupt();
 129                 break;
 130         case IPI_CPU_STOP:
 131                 ipi_stop();
 132                 break;
 133         case IPI_CPU_CRASH_STOP:
 134                 ipi_cpu_crash_stop(smp_processor_id(), get_irq_regs());
 135                 break;
 136         case IPI_IRQ_WORK:
 137                 irq_work_run();
 138                 break;
 139 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
 140         case IPI_TIMER:
 141                 tick_receive_broadcast();
 142                 break;
 143 #endif
 144         default:
 145                 pr_warn("CPU%d: unhandled IPI%d\n", smp_processor_id(), ipi);
 146                 break;
 147         }
 148
 149         return IRQ_HANDLED;
 150 }
 151
 152 void riscv_ipi_enable(void)
 153 {
 154         int i;
 155
 156         if (WARN_ON_ONCE(!ipi_virq_base))
 157                 return;
 158
 159         for (i = 0; i < nr_ipi; i++)
 160                 enable_percpu_irq(ipi_virq_base + i, 0);
 161 }
 162
 163 void riscv_ipi_disable(void)
 164 {
 165         int i;
 166
 167         if (WARN_ON_ONCE(!ipi_virq_base))
 168                 return;
 169
 170         for (i = 0; i < nr_ipi; i++)
 171                 disable_percpu_irq(ipi_virq_base + i);
 172 }
 173
 174 bool riscv_ipi_have_virq_range(void)
 175 {
 176         return (ipi_virq_base) ? true : false;
 177 }
 178
 179 DEFINE_STATIC_KEY_FALSE(riscv_ipi_for_rfence);
 180 EXPORT_SYMBOL_GPL(riscv_ipi_for_rfence);
 181
 182 void riscv_ipi_set_virq_range(int virq, int nr, bool use_for_rfence)
 183 {
 184         int i, err;
 185
 186         if (WARN_ON(ipi_virq_base))
 187                 return;
 188
 189         WARN_ON(nr < IPI_MAX);
 190         nr_ipi = min(nr, IPI_MAX);
 191         ipi_virq_base = virq;
 192
 193         /* Request IPIs */
 194         for (i = 0; i < nr_ipi; i++) {
 195                 err = request_percpu_irq(ipi_virq_base + i, handle_IPI,
 196                                          "IPI", &ipi_dummy_dev);
 197                 WARN_ON(err);
 198
 199                 ipi_desc[i] = irq_to_desc(ipi_virq_base + i);
 200                 irq_set_status_flags(ipi_virq_base + i, IRQ_HIDDEN);
 201         }
 202
 203         /* Enabled IPIs for boot CPU immediately */
 204         riscv_ipi_enable();
 205
 206         /* Update RFENCE static key */
 207         if (use_for_rfence)
 208                 static_branch_enable(&riscv_ipi_for_rfence);
 209         else
 210                 static_branch_disable(&riscv_ipi_for_rfence);
 211 }
 212
 213 static const char * const ipi_names[] = {
 214         [IPI_RESCHEDULE]        = "Rescheduling interrupts",
 215         [IPI_CALL_FUNC]         = "Function call interrupts",
 216         [IPI_CPU_STOP]          = "CPU stop interrupts",
 217         [IPI_CPU_CRASH_STOP]    = "CPU stop (for crash dump) interrupts",
 218         [IPI_IRQ_WORK]          = "IRQ work interrupts",
 219         [IPI_TIMER]             = "Timer broadcast interrupts",
 220 };
 221
 222 void show_ipi_stats(struct seq_file *p, int prec)
 223 {
 224         unsigned int cpu, i;
 225
 226         for (i = 0; i < IPI_MAX; i++) {
 227                 seq_printf(p, "%*s%u:%s", prec - 1, "IPI", i,
 228                            prec >= 4 ? " " : "");
 229                 for_each_online_cpu(cpu)
 230                         seq_printf(p, "%10u ", irq_desc_kstat_cpu(ipi_desc[i], cpu));
 231                 seq_printf(p, " %s\n", ipi_names[i]);
 232         }
 233 }
 234
 235 void arch_send_call_function_ipi_mask(struct cpumask *mask)
 236 {
 237         send_ipi_mask(mask, IPI_CALL_FUNC);
 238 }
 239
 240 void arch_send_call_function_single_ipi(int cpu)
 241 {
 242         send_ipi_single(cpu, IPI_CALL_FUNC);
 243 }
 244
 245 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
 246 void tick_broadcast(const struct cpumask *mask)
 247 {
 248         send_ipi_mask(mask, IPI_TIMER);
 249 }
 250 #endif
 251
 252 void smp_send_stop(void)
 253 {
 254         unsigned long timeout;
 255
 256         if (num_online_cpus() > 1) {
 257                 cpumask_t mask;
 258
 259                 cpumask_copy(&mask, cpu_online_mask);
 260                 cpumask_clear_cpu(smp_processor_id(), &mask);
 261
 262                 if (system_state <= SYSTEM_RUNNING)
 263                         pr_crit("SMP: stopping secondary CPUs\n");
 264                 send_ipi_mask(&mask, IPI_CPU_STOP);
 265         }
 266
 267         /* Wait up to one second for other CPUs to stop */
 268         timeout = USEC_PER_SEC;
 269         while (num_online_cpus() > 1 && timeout--)
 270                 udelay(1);
 271
 272         if (num_online_cpus() > 1)
 273                 pr_warn("SMP: failed to stop secondary CPUs %*pbl\n",
 274                            cpumask_pr_args(cpu_online_mask));
 275 }
 276
 277 #ifdef CONFIG_KEXEC_CORE
 278 /*
 279  * The number of CPUs online, not counting this CPU (which may not be
 280  * fully online and so not counted in num_online_cpus()).
 281  */
 282 static inline unsigned int num_other_online_cpus(void)
 283 {
 284         unsigned int this_cpu_online = cpu_online(smp_processor_id());
 285
 286         return num_online_cpus() - this_cpu_online;
 287 }
 288
 289 void crash_smp_send_stop(void)
 290 {
 291         static int cpus_stopped;
 292         cpumask_t mask;
 293         unsigned long timeout;
 294
 295         /*
 296          * This function can be called twice in panic path, but obviously
 297          * we execute this only once.
 298          */
 299         if (cpus_stopped)
 300                 return;
 301
 302         cpus_stopped = 1;
 303
 304         /*
 305          * If this cpu is the only one alive at this point in time, online or
 306          * not, there are no stop messages to be sent around, so just back out.
 307          */
 308         if (num_other_online_cpus() == 0)
 309                 return;
 310
 311         cpumask_copy(&mask, cpu_online_mask);
 312         cpumask_clear_cpu(smp_processor_id(), &mask);
 313
 314         atomic_set(&waiting_for_crash_ipi, num_other_online_cpus());
 315
 316         pr_crit("SMP: stopping secondary CPUs\n");
 317         send_ipi_mask(&mask, IPI_CPU_CRASH_STOP);
 318
 319         /* Wait up to one second for other CPUs to stop */
 320         timeout = USEC_PER_SEC;
 321         while ((atomic_read(&waiting_for_crash_ipi) > 0) && timeout--)
 322                 udelay(1);
 323
 324         if (atomic_read(&waiting_for_crash_ipi) > 0)
 325                 pr_warn("SMP: failed to stop secondary CPUs %*pbl\n",
 326                         cpumask_pr_args(&mask));
 327 }
 328
 329 bool smp_crash_stop_failed(void)
 330 {
 331         return (atomic_read(&waiting_for_crash_ipi) > 0);
 332 }
 333 #endif
 334
 335 void arch_smp_send_reschedule(int cpu)
 336 {
 337         send_ipi_single(cpu, IPI_RESCHEDULE);
 338 }
 339 EXPORT_SYMBOL_GPL(arch_smp_send_reschedule);