linux/arch/powerpc/platforms/powernv/smp.c
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   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/smp.h>
  16#include <linux/interrupt.h>
  17#include <linux/delay.h>
  18#include <linux/init.h>
  19#include <linux/spinlock.h>
  20#include <linux/cpu.h>
  21
  22#include <asm/irq.h>
  23#include <asm/smp.h>
  24#include <asm/paca.h>
  25#include <asm/machdep.h>
  26#include <asm/cputable.h>
  27#include <asm/firmware.h>
  28#include <asm/rtas.h>
  29#include <asm/vdso_datapage.h>
  30#include <asm/cputhreads.h>
  31#include <asm/xics.h>
  32#include <asm/opal.h>
  33
  34#include "powernv.h"
  35
  36#ifdef DEBUG
  37#include <asm/udbg.h>
  38#define DBG(fmt...) udbg_printf(fmt)
  39#else
  40#define DBG(fmt...)
  41#endif
  42
  43static void pnv_smp_setup_cpu(int cpu)
  44{
  45        if (cpu != boot_cpuid)
  46                xics_setup_cpu();
  47}
  48
  49int pnv_smp_kick_cpu(int nr)
  50{
  51        unsigned int pcpu = get_hard_smp_processor_id(nr);
  52        unsigned long start_here = __pa(*((unsigned long *)
  53                                          generic_secondary_smp_init));
  54        long rc;
  55
  56        BUG_ON(nr < 0 || nr >= NR_CPUS);
  57
  58        /*
  59         * If we already started or OPALv2 is not supported, we just
  60         * kick the CPU via the PACA
  61         */
  62        if (paca[nr].cpu_start || !firmware_has_feature(FW_FEATURE_OPALv2))
  63                goto kick;
  64
  65        /*
  66         * At this point, the CPU can either be spinning on the way in
  67         * from kexec or be inside OPAL waiting to be started for the
  68         * first time. OPAL v3 allows us to query OPAL to know if it
  69         * has the CPUs, so we do that
  70         */
  71        if (firmware_has_feature(FW_FEATURE_OPALv3)) {
  72                uint8_t status;
  73
  74                rc = opal_query_cpu_status(pcpu, &status);
  75                if (rc != OPAL_SUCCESS) {
  76                        pr_warn("OPAL Error %ld querying CPU %d state\n",
  77                                rc, nr);
  78                        return -ENODEV;
  79                }
  80
  81                /*
  82                 * Already started, just kick it, probably coming from
  83                 * kexec and spinning
  84                 */
  85                if (status == OPAL_THREAD_STARTED)
  86                        goto kick;
  87
  88                /*
  89                 * Available/inactive, let's kick it
  90                 */
  91                if (status == OPAL_THREAD_INACTIVE) {
  92                        pr_devel("OPAL: Starting CPU %d (HW 0x%x)...\n",
  93                                 nr, pcpu);
  94                        rc = opal_start_cpu(pcpu, start_here);
  95                        if (rc != OPAL_SUCCESS) {
  96                                pr_warn("OPAL Error %ld starting CPU %d\n",
  97                                        rc, nr);
  98                                return -ENODEV;
  99                        }
 100                } else {
 101                        /*
 102                         * An unavailable CPU (or any other unknown status)
 103                         * shouldn't be started. It should also
 104                         * not be in the possible map but currently it can
 105                         * happen
 106                         */
 107                        pr_devel("OPAL: CPU %d (HW 0x%x) is unavailable"
 108                                 " (status %d)...\n", nr, pcpu, status);
 109                        return -ENODEV;
 110                }
 111        } else {
 112                /*
 113                 * On OPAL v2, we just kick it and hope for the best,
 114                 * we must not test the error from opal_start_cpu() or
 115                 * we would fail to get CPUs from kexec.
 116                 */
 117                opal_start_cpu(pcpu, start_here);
 118        }
 119 kick:
 120        return smp_generic_kick_cpu(nr);
 121}
 122
 123#ifdef CONFIG_HOTPLUG_CPU
 124
 125static int pnv_smp_cpu_disable(void)
 126{
 127        int cpu = smp_processor_id();
 128
 129        /* This is identical to pSeries... might consolidate by
 130         * moving migrate_irqs_away to a ppc_md with default to
 131         * the generic fixup_irqs. --BenH.
 132         */
 133        set_cpu_online(cpu, false);
 134        vdso_data->processorCount--;
 135        if (cpu == boot_cpuid)
 136                boot_cpuid = cpumask_any(cpu_online_mask);
 137        xics_migrate_irqs_away();
 138        return 0;
 139}
 140
 141static void pnv_smp_cpu_kill_self(void)
 142{
 143        unsigned int cpu;
 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        /* We don't want to take decrementer interrupts while we are offline,
 155         * so clear LPCR:PECE1. We keep PECE2 enabled.
 156         */
 157        mtspr(SPRN_LPCR, mfspr(SPRN_LPCR) & ~(u64)LPCR_PECE1);
 158        while (!generic_check_cpu_restart(cpu)) {
 159                power7_nap();
 160                if (!generic_check_cpu_restart(cpu)) {
 161                        DBG("CPU%d Unexpected exit while offline !\n", cpu);
 162                        /* We may be getting an IPI, so we re-enable
 163                         * interrupts to process it, it will be ignored
 164                         * since we aren't online (hopefully)
 165                         */
 166                        local_irq_enable();
 167                        local_irq_disable();
 168                }
 169        }
 170        mtspr(SPRN_LPCR, mfspr(SPRN_LPCR) | LPCR_PECE1);
 171        DBG("CPU%d coming online...\n", cpu);
 172}
 173
 174#endif /* CONFIG_HOTPLUG_CPU */
 175
 176static struct smp_ops_t pnv_smp_ops = {
 177        .message_pass   = smp_muxed_ipi_message_pass,
 178        .cause_ipi      = NULL, /* Filled at runtime by xics_smp_probe() */
 179        .probe          = xics_smp_probe,
 180        .kick_cpu       = pnv_smp_kick_cpu,
 181        .setup_cpu      = pnv_smp_setup_cpu,
 182        .cpu_bootable   = smp_generic_cpu_bootable,
 183#ifdef CONFIG_HOTPLUG_CPU
 184        .cpu_disable    = pnv_smp_cpu_disable,
 185        .cpu_die        = generic_cpu_die,
 186#endif /* CONFIG_HOTPLUG_CPU */
 187};
 188
 189/* This is called very early during platform setup_arch */
 190void __init pnv_smp_init(void)
 191{
 192        smp_ops = &pnv_smp_ops;
 193
 194        /* XXX We don't yet have a proper entry point from HAL, for
 195         * now we rely on kexec-style entry from BML
 196         */
 197
 198#ifdef CONFIG_PPC_RTAS
 199        /* Non-lpar has additional take/give timebase */
 200        if (rtas_token("freeze-time-base") != RTAS_UNKNOWN_SERVICE) {
 201                smp_ops->give_timebase = rtas_give_timebase;
 202                smp_ops->take_timebase = rtas_take_timebase;
 203        }
 204#endif /* CONFIG_PPC_RTAS */
 205
 206#ifdef CONFIG_HOTPLUG_CPU
 207        ppc_md.cpu_die  = pnv_smp_cpu_kill_self;
 208#endif
 209}
 210