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