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/opal.h>
  33 #include <asm/runlatch.h>
  34 #include <asm/code-patching.h>
  35 #include <asm/dbell.h>
  36 #include <asm/kvm_ppc.h>
  37 #include <asm/ppc-opcode.h>
  38
  39 #include "powernv.h"
  40
  41 #ifdef DEBUG
  42 #include <asm/udbg.h>
  43 #define DBG(fmt...) udbg_printf(fmt)
  44 #else
  45 #define DBG(fmt...)
  46 #endif
  47
  48 static void pnv_smp_setup_cpu(int cpu)
  49 {
  50         if (cpu != boot_cpuid)
  51                 xics_setup_cpu();
  52
  53 #ifdef CONFIG_PPC_DOORBELL
  54         if (cpu_has_feature(CPU_FTR_DBELL))
  55                 doorbell_setup_this_cpu();
  56 #endif
  57 }
  58
  59 static int pnv_smp_kick_cpu(int nr)
  60 {
  61         unsigned int pcpu = get_hard_smp_processor_id(nr);
  62         unsigned long start_here =
  63                         __pa(ppc_function_entry(generic_secondary_smp_init));
  64         long rc;
  65         uint8_t status;
  66
  67         BUG_ON(nr < 0 || nr >= NR_CPUS);
  68
  69         /*
  70          * If we already started or OPAL is not supported, we just
  71          * kick the CPU via the PACA
  72          */
  73         if (paca[nr].cpu_start || !firmware_has_feature(FW_FEATURE_OPAL))
  74                 goto kick;
  75
  76         /*
  77          * At this point, the CPU can either be spinning on the way in
  78          * from kexec or be inside OPAL waiting to be started for the
  79          * first time. OPAL v3 allows us to query OPAL to know if it
  80          * has the CPUs, so we do that
  81          */
  82         rc = opal_query_cpu_status(pcpu, &status);
  83         if (rc != OPAL_SUCCESS) {
  84                 pr_warn("OPAL Error %ld querying CPU %d state\n", rc, nr);
  85                 return -ENODEV;
  86         }
  87
  88         /*
  89          * Already started, just kick it, probably coming from
  90          * kexec and spinning
  91          */
  92         if (status == OPAL_THREAD_STARTED)
  93                 goto kick;
  94
  95         /*
  96          * Available/inactive, let's kick it
  97          */
  98         if (status == OPAL_THREAD_INACTIVE) {
  99                 pr_devel("OPAL: Starting CPU %d (HW 0x%x)...\n", nr, pcpu);
 100                 rc = opal_start_cpu(pcpu, start_here);
 101                 if (rc != OPAL_SUCCESS) {
 102                         pr_warn("OPAL Error %ld starting CPU %d\n", rc, nr);
 103                         return -ENODEV;
 104                 }
 105         } else {
 106                 /*
 107                  * An unavailable CPU (or any other unknown status)
 108                  * shouldn't be started. It should also
 109                  * not be in the possible map but currently it can
 110                  * happen
 111                  */
 112                 pr_devel("OPAL: CPU %d (HW 0x%x) is unavailable"
 113                          " (status %d)...\n", nr, pcpu, status);
 114                 return -ENODEV;
 115         }
 116
 117 kick:
 118         return smp_generic_kick_cpu(nr);
 119 }
 120
 121 #ifdef CONFIG_HOTPLUG_CPU
 122
 123 static int pnv_smp_cpu_disable(void)
 124 {
 125         int cpu = smp_processor_id();
 126
 127         /* This is identical to pSeries... might consolidate by
 128          * moving migrate_irqs_away to a ppc_md with default to
 129          * the generic fixup_irqs. --BenH.
 130          */
 131         set_cpu_online(cpu, false);
 132         vdso_data->processorCount--;
 133         if (cpu == boot_cpuid)
 134                 boot_cpuid = cpumask_any(cpu_online_mask);
 135         xics_migrate_irqs_away();
 136         return 0;
 137 }
 138
 139 static void pnv_smp_cpu_kill_self(void)
 140 {
 141         unsigned int cpu;
 142         unsigned long srr1, wmask;
 143         u32 idle_states;
 144
 145         /* Standard hot unplug procedure */
 146         local_irq_disable();
 147         idle_task_exit();
 148         current->active_mm = NULL; /* for sanity */
 149         cpu = smp_processor_id();
 150         DBG("CPU%d offline\n", cpu);
 151         generic_set_cpu_dead(cpu);
 152         smp_wmb();
 153
 154         wmask = SRR1_WAKEMASK;
 155         if (cpu_has_feature(CPU_FTR_ARCH_207S))
 156                 wmask = SRR1_WAKEMASK_P8;
 157
 158         idle_states = pnv_get_supported_cpuidle_states();
 159
 160         /* We don't want to take decrementer interrupts while we are offline,
 161          * so clear LPCR:PECE1. We keep PECE2 (and LPCR_PECE_HVEE on P9)
 162          * enabled as to let IPIs in.
 163          */
 164         mtspr(SPRN_LPCR, mfspr(SPRN_LPCR) & ~(u64)LPCR_PECE1);
 165
 166         /*
 167          * Hard-disable interrupts, and then clear irq_happened flags
 168          * that we can safely ignore while off-line, since they
 169          * are for things for which we do no processing when off-line
 170          * (or in the case of HMI, all the processing we need to do
 171          * is done in lower-level real-mode code).
 172          */
 173         hard_irq_disable();
 174         local_paca->irq_happened &= ~(PACA_IRQ_DEC | PACA_IRQ_HMI);
 175
 176         while (!generic_check_cpu_restart(cpu)) {
 177                 /*
 178                  * Clear IPI flag, since we don't handle IPIs while
 179                  * offline, except for those when changing micro-threading
 180                  * mode, which are handled explicitly below, and those
 181                  * for coming online, which are handled via
 182                  * generic_check_cpu_restart() calls.
 183                  */
 184                 kvmppc_set_host_ipi(cpu, 0);
 185
 186                 ppc64_runlatch_off();
 187
 188                 if (cpu_has_feature(CPU_FTR_ARCH_300)) {
 189                         srr1 = power9_idle_stop(pnv_deepest_stop_psscr_val,
 190                                                 pnv_deepest_stop_psscr_mask);
 191                 } else if (idle_states & OPAL_PM_WINKLE_ENABLED) {
 192                         srr1 = power7_winkle();
 193                 } else if ((idle_states & OPAL_PM_SLEEP_ENABLED) ||
 194                            (idle_states & OPAL_PM_SLEEP_ENABLED_ER1)) {
 195                         srr1 = power7_sleep();
 196                 } else {
 197                         srr1 = power7_nap(1);
 198                 }
 199
 200                 ppc64_runlatch_on();
 201
 202                 /*
 203                  * If the SRR1 value indicates that we woke up due to
 204                  * an external interrupt, then clear the interrupt.
 205                  * We clear the interrupt before checking for the
 206                  * reason, so as to avoid a race where we wake up for
 207                  * some other reason, find nothing and clear the interrupt
 208                  * just as some other cpu is sending us an interrupt.
 209                  * If we returned from power7_nap as a result of
 210                  * having finished executing in a KVM guest, then srr1
 211                  * contains 0.
 212                  */
 213                 if (((srr1 & wmask) == SRR1_WAKEEE) ||
 214                     ((srr1 & wmask) == SRR1_WAKEHVI) ||
 215                     (local_paca->irq_happened & PACA_IRQ_EE)) {
 216                         if (cpu_has_feature(CPU_FTR_ARCH_300))
 217                                 icp_opal_flush_interrupt();
 218                         else
 219                                 icp_native_flush_interrupt();
 220                 } else if ((srr1 & wmask) == SRR1_WAKEHDBELL) {
 221                         unsigned long msg = PPC_DBELL_TYPE(PPC_DBELL_SERVER);
 222                         asm volatile(PPC_MSGCLR(%0) : : "r" (msg));
 223                 }
 224                 local_paca->irq_happened &= ~(PACA_IRQ_EE | PACA_IRQ_DBELL);
 225                 smp_mb();
 226
 227                 if (cpu_core_split_required())
 228                         continue;
 229
 230                 if (srr1 && !generic_check_cpu_restart(cpu))
 231                         DBG("CPU%d Unexpected exit while offline !\n", cpu);
 232         }
 233
 234         /* Re-enable decrementer interrupts */
 235         mtspr(SPRN_LPCR, mfspr(SPRN_LPCR) | LPCR_PECE1);
 236         DBG("CPU%d coming online...\n", cpu);
 237 }
 238
 239 #endif /* CONFIG_HOTPLUG_CPU */
 240
 241 static int pnv_cpu_bootable(unsigned int nr)
 242 {
 243         /*
 244          * Starting with POWER8, the subcore logic relies on all threads of a
 245          * core being booted so that they can participate in split mode
 246          * switches. So on those machines we ignore the smt_enabled_at_boot
 247          * setting (smt-enabled on the kernel command line).
 248          */
 249         if (cpu_has_feature(CPU_FTR_ARCH_207S))
 250                 return 1;
 251
 252         return smp_generic_cpu_bootable(nr);
 253 }
 254
 255 static struct smp_ops_t pnv_smp_ops = {
 256         .message_pass   = smp_muxed_ipi_message_pass,
 257         .cause_ipi      = NULL, /* Filled at runtime by xics_smp_probe() */
 258         .probe          = xics_smp_probe,
 259         .kick_cpu       = pnv_smp_kick_cpu,
 260         .setup_cpu      = pnv_smp_setup_cpu,
 261         .cpu_bootable   = pnv_cpu_bootable,
 262 #ifdef CONFIG_HOTPLUG_CPU
 263         .cpu_disable    = pnv_smp_cpu_disable,
 264         .cpu_die        = generic_cpu_die,
 265 #endif /* CONFIG_HOTPLUG_CPU */
 266 };
 267
 268 /* This is called very early during platform setup_arch */
 269 void __init pnv_smp_init(void)
 270 {
 271         smp_ops = &pnv_smp_ops;
 272
 273 #ifdef CONFIG_HOTPLUG_CPU
 274         ppc_md.cpu_die  = pnv_smp_cpu_kill_self;
 275 #endif
 276 }