arch/powerpc/platforms/powernv/smp.c

   1 /*
   2  * SMP support for PowerNV machines.
   3  *
   4  * Copyright 2011 IBM Corp.
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the License, or (at your option) any later version.
  10  */
  11
  12 #include <linux/kernel.h>
  13 #include <linux/module.h>
  14 #include <linux/sched.h>
  15 #include <linux/sched/hotplug.h>
  16 #include <linux/smp.h>
  17 #include <linux/interrupt.h>
  18 #include <linux/delay.h>
  19 #include <linux/init.h>
  20 #include <linux/spinlock.h>
  21 #include <linux/cpu.h>
  22
  23 #include <asm/irq.h>
  24 #include <asm/smp.h>
  25 #include <asm/paca.h>
  26 #include <asm/machdep.h>
  27 #include <asm/cputable.h>
  28 #include <asm/firmware.h>
  29 #include <asm/vdso_datapage.h>
  30 #include <asm/cputhreads.h>
  31 #include <asm/xics.h>
  32 #include <asm/xive.h>
  33 #include <asm/opal.h>
  34 #include <asm/runlatch.h>
  35 #include <asm/code-patching.h>
  36 #include <asm/dbell.h>
  37 #include <asm/kvm_ppc.h>
  38 #include <asm/ppc-opcode.h>
  39 #include <asm/cpuidle.h>
  40
  41 #include "powernv.h"
  42
  43 #ifdef DEBUG
  44 #include <asm/udbg.h>
  45 #define DBG(fmt...) udbg_printf(fmt)
  46 #else
  47 #define DBG(fmt...)
  48 #endif
  49
  50 static void pnv_smp_setup_cpu(int cpu)
  51 {
  52         if (xive_enabled())
  53                 xive_smp_setup_cpu();
  54         else if (cpu != boot_cpuid)
  55                 xics_setup_cpu();
  56 }
  57
  58 static int pnv_smp_kick_cpu(int nr)
  59 {
  60         unsigned int pcpu;
  61         unsigned long start_here =
  62                         __pa(ppc_function_entry(generic_secondary_smp_init));
  63         long rc;
  64         uint8_t status;
  65
  66         if (nr < 0 || nr >= nr_cpu_ids)
  67                 return -EINVAL;
  68
  69         pcpu = get_hard_smp_processor_id(nr);
  70         /*
  71          * If we already started or OPAL is not supported, we just
  72          * kick the CPU via the PACA
  73          */
  74         if (paca[nr].cpu_start || !firmware_has_feature(FW_FEATURE_OPAL))
  75                 goto kick;
  76
  77         /*
  78          * At this point, the CPU can either be spinning on the way in
  79          * from kexec or be inside OPAL waiting to be started for the
  80          * first time. OPAL v3 allows us to query OPAL to know if it
  81          * has the CPUs, so we do that
  82          */
  83         rc = opal_query_cpu_status(pcpu, &status);
  84         if (rc != OPAL_SUCCESS) {
  85                 pr_warn("OPAL Error %ld querying CPU %d state\n", rc, nr);
  86                 return -ENODEV;
  87         }
  88
  89         /*
  90          * Already started, just kick it, probably coming from
  91          * kexec and spinning
  92          */
  93         if (status == OPAL_THREAD_STARTED)
  94                 goto kick;
  95
  96         /*
  97          * Available/inactive, let's kick it
  98          */
  99         if (status == OPAL_THREAD_INACTIVE) {
 100                 pr_devel("OPAL: Starting CPU %d (HW 0x%x)...\n", nr, pcpu);
 101                 rc = opal_start_cpu(pcpu, start_here);
 102                 if (rc != OPAL_SUCCESS) {
 103                         pr_warn("OPAL Error %ld starting CPU %d\n", rc, nr);
 104                         return -ENODEV;
 105                 }
 106         } else {
 107                 /*
 108                  * An unavailable CPU (or any other unknown status)
 109                  * shouldn't be started. It should also
 110                  * not be in the possible map but currently it can
 111                  * happen
 112                  */
 113                 pr_devel("OPAL: CPU %d (HW 0x%x) is unavailable"
 114                          " (status %d)...\n", nr, pcpu, status);
 115                 return -ENODEV;
 116         }
 117
 118 kick:
 119         return smp_generic_kick_cpu(nr);
 120 }
 121
 122 #ifdef CONFIG_HOTPLUG_CPU
 123
 124 static int pnv_smp_cpu_disable(void)
 125 {
 126         int cpu = smp_processor_id();
 127
 128         /* This is identical to pSeries... might consolidate by
 129          * moving migrate_irqs_away to a ppc_md with default to
 130          * the generic fixup_irqs. --BenH.
 131          */
 132         set_cpu_online(cpu, false);
 133         vdso_data->processorCount--;
 134         if (cpu == boot_cpuid)
 135                 boot_cpuid = cpumask_any(cpu_online_mask);
 136         if (xive_enabled())
 137                 xive_smp_disable_cpu();
 138         else
 139                 xics_migrate_irqs_away();
 140         return 0;
 141 }
 142
 143 static void pnv_smp_cpu_kill_self(void)
 144 {
 145         unsigned int cpu;
 146         unsigned long srr1, wmask;
 147
 148         /* Standard hot unplug procedure */
 149         /*
 150          * This hard disables local interurpts, ensuring we have no lazy
 151          * irqs pending.
 152          */
 153         WARN_ON(irqs_disabled());
 154         hard_irq_disable();
 155         WARN_ON(lazy_irq_pending());
 156
 157         idle_task_exit();
 158         current->active_mm = NULL; /* for sanity */
 159         cpu = smp_processor_id();
 160         DBG("CPU%d offline\n", cpu);
 161         generic_set_cpu_dead(cpu);
 162         smp_wmb();
 163
 164         wmask = SRR1_WAKEMASK;
 165         if (cpu_has_feature(CPU_FTR_ARCH_207S))
 166                 wmask = SRR1_WAKEMASK_P8;
 167
 168         while (!generic_check_cpu_restart(cpu)) {
 169                 /*
 170                  * Clear IPI flag, since we don't handle IPIs while
 171                  * offline, except for those when changing micro-threading
 172                  * mode, which are handled explicitly below, and those
 173                  * for coming online, which are handled via
 174                  * generic_check_cpu_restart() calls.
 175                  */
 176                 kvmppc_set_host_ipi(cpu, 0);
 177
 178                 srr1 = pnv_cpu_offline(cpu);
 179
 180                 WARN_ON(lazy_irq_pending());
 181
 182                 /*
 183                  * If the SRR1 value indicates that we woke up due to
 184                  * an external interrupt, then clear the interrupt.
 185                  * We clear the interrupt before checking for the
 186                  * reason, so as to avoid a race where we wake up for
 187                  * some other reason, find nothing and clear the interrupt
 188                  * just as some other cpu is sending us an interrupt.
 189                  * If we returned from power7_nap as a result of
 190                  * having finished executing in a KVM guest, then srr1
 191                  * contains 0.
 192                  */
 193                 if (((srr1 & wmask) == SRR1_WAKEEE) ||
 194                     ((srr1 & wmask) == SRR1_WAKEHVI)) {
 195                         if (cpu_has_feature(CPU_FTR_ARCH_300)) {
 196                                 if (xive_enabled())
 197                                         xive_flush_interrupt();
 198                                 else
 199                                         icp_opal_flush_interrupt();
 200                         } else
 201                                 icp_native_flush_interrupt();
 202                 } else if ((srr1 & wmask) == SRR1_WAKEHDBELL) {
 203                         unsigned long msg = PPC_DBELL_TYPE(PPC_DBELL_SERVER);
 204                         asm volatile(PPC_MSGCLR(%0) : : "r" (msg));
 205                 }
 206                 smp_mb();
 207
 208                 if (cpu_core_split_required())
 209                         continue;
 210
 211                 if (srr1 && !generic_check_cpu_restart(cpu))
 212                         DBG("CPU%d Unexpected exit while offline srr1=%lx!\n",
 213                                         cpu, srr1);
 214
 215         }
 216
 217         DBG("CPU%d coming online...\n", cpu);
 218 }
 219
 220 #endif /* CONFIG_HOTPLUG_CPU */
 221
 222 static int pnv_cpu_bootable(unsigned int nr)
 223 {
 224         /*
 225          * Starting with POWER8, the subcore logic relies on all threads of a
 226          * core being booted so that they can participate in split mode
 227          * switches. So on those machines we ignore the smt_enabled_at_boot
 228          * setting (smt-enabled on the kernel command line).
 229          */
 230         if (cpu_has_feature(CPU_FTR_ARCH_207S))
 231                 return 1;
 232
 233         return smp_generic_cpu_bootable(nr);
 234 }
 235
 236 static int pnv_smp_prepare_cpu(int cpu)
 237 {
 238         if (xive_enabled())
 239                 return xive_smp_prepare_cpu(cpu);
 240         return 0;
 241 }
 242
 243 /* Cause IPI as setup by the interrupt controller (xics or xive) */
 244 static void (*ic_cause_ipi)(int cpu);
 245
 246 static void pnv_cause_ipi(int cpu)
 247 {
 248         if (doorbell_try_core_ipi(cpu))
 249                 return;
 250
 251         ic_cause_ipi(cpu);
 252 }
 253
 254 static void pnv_p9_dd1_cause_ipi(int cpu)
 255 {
 256         int this_cpu = get_cpu();
 257
 258         /*
 259          * POWER9 DD1 has a global addressed msgsnd, but for now we restrict
 260          * IPIs to same core, because it requires additional synchronization
 261          * for inter-core doorbells which we do not implement.
 262          */
 263         if (cpumask_test_cpu(cpu, cpu_sibling_mask(this_cpu)))
 264                 doorbell_global_ipi(cpu);
 265         else
 266                 ic_cause_ipi(cpu);
 267
 268         put_cpu();
 269 }
 270
 271 static void __init pnv_smp_probe(void)
 272 {
 273         if (xive_enabled())
 274                 xive_smp_probe();
 275         else
 276                 xics_smp_probe();
 277
 278         if (cpu_has_feature(CPU_FTR_DBELL)) {
 279                 ic_cause_ipi = smp_ops->cause_ipi;
 280                 WARN_ON(!ic_cause_ipi);
 281
 282                 if (cpu_has_feature(CPU_FTR_ARCH_300)) {
 283                         if (cpu_has_feature(CPU_FTR_POWER9_DD1))
 284                                 smp_ops->cause_ipi = pnv_p9_dd1_cause_ipi;
 285                         else
 286                                 smp_ops->cause_ipi = doorbell_global_ipi;
 287                 } else {
 288                         smp_ops->cause_ipi = pnv_cause_ipi;
 289                 }
 290         }
 291 }
 292
 293 static struct smp_ops_t pnv_smp_ops = {
 294         .message_pass   = NULL, /* Use smp_muxed_ipi_message_pass */
 295         .cause_ipi      = NULL, /* Filled at runtime by pnv_smp_probe() */
 296         .cause_nmi_ipi  = NULL,
 297         .probe          = pnv_smp_probe,
 298         .prepare_cpu    = pnv_smp_prepare_cpu,
 299         .kick_cpu       = pnv_smp_kick_cpu,
 300         .setup_cpu      = pnv_smp_setup_cpu,
 301         .cpu_bootable   = pnv_cpu_bootable,
 302 #ifdef CONFIG_HOTPLUG_CPU
 303         .cpu_disable    = pnv_smp_cpu_disable,
 304         .cpu_die        = generic_cpu_die,
 305 #endif /* CONFIG_HOTPLUG_CPU */
 306 };
 307
 308 /* This is called very early during platform setup_arch */
 309 void __init pnv_smp_init(void)
 310 {
 311         smp_ops = &pnv_smp_ops;
 312
 313 #ifdef CONFIG_HOTPLUG_CPU
 314         ppc_md.cpu_die  = pnv_smp_cpu_kill_self;
 315 #endif
 316 }