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/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 #include <asm/runlatch.h>
  34 #include <asm/code-patching.h>
  35 #include <asm/dbell.h>
  36
  37 #include "powernv.h"
  38
  39 #ifdef DEBUG
  40 #include <asm/udbg.h>
  41 #define DBG(fmt...) udbg_printf(fmt)
  42 #else
  43 #define DBG(fmt...)
  44 #endif
  45
  46 static void pnv_smp_setup_cpu(int cpu)
  47 {
  48         if (cpu != boot_cpuid)
  49                 xics_setup_cpu();
  50
  51 #ifdef CONFIG_PPC_DOORBELL
  52         if (cpu_has_feature(CPU_FTR_DBELL))
  53                 doorbell_setup_this_cpu();
  54 #endif
  55 }
  56
  57 static int pnv_smp_kick_cpu(int nr)
  58 {
  59         unsigned int pcpu = get_hard_smp_processor_id(nr);
  60         unsigned long start_here =
  61                         __pa(ppc_function_entry(generic_secondary_smp_init));
  62         long rc;
  63
  64         BUG_ON(nr < 0 || nr >= NR_CPUS);
  65
  66         /*
  67          * If we already started or OPALv2 is not supported, we just
  68          * kick the CPU via the PACA
  69          */
  70         if (paca[nr].cpu_start || !firmware_has_feature(FW_FEATURE_OPALv2))
  71                 goto kick;
  72
  73         /*
  74          * At this point, the CPU can either be spinning on the way in
  75          * from kexec or be inside OPAL waiting to be started for the
  76          * first time. OPAL v3 allows us to query OPAL to know if it
  77          * has the CPUs, so we do that
  78          */
  79         if (firmware_has_feature(FW_FEATURE_OPALv3)) {
  80                 uint8_t status;
  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",
  85                                 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",
 101                                  nr, pcpu);
 102                         rc = opal_start_cpu(pcpu, start_here);
 103                         if (rc != OPAL_SUCCESS) {
 104                                 pr_warn("OPAL Error %ld starting CPU %d\n",
 105                                         rc, nr);
 106                                 return -ENODEV;
 107                         }
 108                 } else {
 109                         /*
 110                          * An unavailable CPU (or any other unknown status)
 111                          * shouldn't be started. It should also
 112                          * not be in the possible map but currently it can
 113                          * happen
 114                          */
 115                         pr_devel("OPAL: CPU %d (HW 0x%x) is unavailable"
 116                                  " (status %d)...\n", nr, pcpu, status);
 117                         return -ENODEV;
 118                 }
 119         } else {
 120                 /*
 121                  * On OPAL v2, we just kick it and hope for the best,
 122                  * we must not test the error from opal_start_cpu() or
 123                  * we would fail to get CPUs from kexec.
 124                  */
 125                 opal_start_cpu(pcpu, start_here);
 126         }
 127  kick:
 128         return smp_generic_kick_cpu(nr);
 129 }
 130
 131 #ifdef CONFIG_HOTPLUG_CPU
 132
 133 static int pnv_smp_cpu_disable(void)
 134 {
 135         int cpu = smp_processor_id();
 136
 137         /* This is identical to pSeries... might consolidate by
 138          * moving migrate_irqs_away to a ppc_md with default to
 139          * the generic fixup_irqs. --BenH.
 140          */
 141         set_cpu_online(cpu, false);
 142         vdso_data->processorCount--;
 143         if (cpu == boot_cpuid)
 144                 boot_cpuid = cpumask_any(cpu_online_mask);
 145         xics_migrate_irqs_away();
 146         return 0;
 147 }
 148
 149 static void pnv_smp_cpu_kill_self(void)
 150 {
 151         unsigned int cpu;
 152         unsigned long srr1;
 153
 154         /* Standard hot unplug procedure */
 155         local_irq_disable();
 156         idle_task_exit();
 157         current->active_mm = NULL; /* for sanity */
 158         cpu = smp_processor_id();
 159         DBG("CPU%d offline\n", cpu);
 160         generic_set_cpu_dead(cpu);
 161         smp_wmb();
 162
 163         /* We don't want to take decrementer interrupts while we are offline,
 164          * so clear LPCR:PECE1. We keep PECE2 enabled.
 165          */
 166         mtspr(SPRN_LPCR, mfspr(SPRN_LPCR) & ~(u64)LPCR_PECE1);
 167         while (!generic_check_cpu_restart(cpu)) {
 168                 ppc64_runlatch_off();
 169                 srr1 = power7_nap(1);
 170                 ppc64_runlatch_on();
 171
 172                 /*
 173                  * If the SRR1 value indicates that we woke up due to
 174                  * an external interrupt, then clear the interrupt.
 175                  * We clear the interrupt before checking for the
 176                  * reason, so as to avoid a race where we wake up for
 177                  * some other reason, find nothing and clear the interrupt
 178                  * just as some other cpu is sending us an interrupt.
 179                  * If we returned from power7_nap as a result of
 180                  * having finished executing in a KVM guest, then srr1
 181                  * contains 0.
 182                  */
 183                 if ((srr1 & SRR1_WAKEMASK) == SRR1_WAKEEE) {
 184                         icp_native_flush_interrupt();
 185                         local_paca->irq_happened &= PACA_IRQ_HARD_DIS;
 186                         smp_mb();
 187                 }
 188
 189                 if (cpu_core_split_required())
 190                         continue;
 191
 192                 if (!generic_check_cpu_restart(cpu))
 193                         DBG("CPU%d Unexpected exit while offline !\n", cpu);
 194         }
 195         mtspr(SPRN_LPCR, mfspr(SPRN_LPCR) | LPCR_PECE1);
 196         DBG("CPU%d coming online...\n", cpu);
 197 }
 198
 199 #endif /* CONFIG_HOTPLUG_CPU */
 200
 201 static struct smp_ops_t pnv_smp_ops = {
 202         .message_pass   = smp_muxed_ipi_message_pass,
 203         .cause_ipi      = NULL, /* Filled at runtime by xics_smp_probe() */
 204         .probe          = xics_smp_probe,
 205         .kick_cpu       = pnv_smp_kick_cpu,
 206         .setup_cpu      = pnv_smp_setup_cpu,
 207         .cpu_bootable   = smp_generic_cpu_bootable,
 208 #ifdef CONFIG_HOTPLUG_CPU
 209         .cpu_disable    = pnv_smp_cpu_disable,
 210         .cpu_die        = generic_cpu_die,
 211 #endif /* CONFIG_HOTPLUG_CPU */
 212 };
 213
 214 /* This is called very early during platform setup_arch */
 215 void __init pnv_smp_init(void)
 216 {
 217         smp_ops = &pnv_smp_ops;
 218
 219         /* XXX We don't yet have a proper entry point from HAL, for
 220          * now we rely on kexec-style entry from BML
 221          */
 222
 223 #ifdef CONFIG_PPC_RTAS
 224         /* Non-lpar has additional take/give timebase */
 225         if (rtas_token("freeze-time-base") != RTAS_UNKNOWN_SERVICE) {
 226                 smp_ops->give_timebase = rtas_give_timebase;
 227                 smp_ops->take_timebase = rtas_take_timebase;
 228         }
 229 #endif /* CONFIG_PPC_RTAS */
 230
 231 #ifdef CONFIG_HOTPLUG_CPU
 232         ppc_md.cpu_die  = pnv_smp_cpu_kill_self;
 233 #endif
 234 }