arch/powerpc/platforms/pseries/smp.c

   1 /*
   2  * SMP support for pSeries machines.
   3  *
   4  * Dave Engebretsen, Peter Bergner, and
   5  * Mike Corrigan {engebret|bergner|mikec}@us.ibm.com
   6  *
   7  * Plus various changes from other IBM teams...
   8  *
   9  *      This program is free software; you can redistribute it and/or
  10  *      modify it under the terms of the GNU General Public License
  11  *      as published by the Free Software Foundation; either version
  12  *      2 of the License, or (at your option) any later version.
  13  */
  14
  15
  16 #include <linux/kernel.h>
  17 #include <linux/module.h>
  18 #include <linux/sched.h>
  19 #include <linux/smp.h>
  20 #include <linux/interrupt.h>
  21 #include <linux/delay.h>
  22 #include <linux/init.h>
  23 #include <linux/spinlock.h>
  24 #include <linux/cache.h>
  25 #include <linux/err.h>
  26 #include <linux/sysdev.h>
  27 #include <linux/cpu.h>
  28
  29 #include <asm/ptrace.h>
  30 #include <asm/atomic.h>
  31 #include <asm/irq.h>
  32 #include <asm/page.h>
  33 #include <asm/pgtable.h>
  34 #include <asm/io.h>
  35 #include <asm/prom.h>
  36 #include <asm/smp.h>
  37 #include <asm/paca.h>
  38 #include <asm/machdep.h>
  39 #include <asm/cputable.h>
  40 #include <asm/firmware.h>
  41 #include <asm/system.h>
  42 #include <asm/rtas.h>
  43 #include <asm/pSeries_reconfig.h>
  44 #include <asm/mpic.h>
  45 #include <asm/vdso_datapage.h>
  46 #include <asm/cputhreads.h>
  47 #include <asm/mpic.h>
  48 #include <asm/xics.h>
  49
  50 #include "plpar_wrappers.h"
  51 #include "pseries.h"
  52 #include "offline_states.h"
  53
  54
  55 /*
  56  * The Primary thread of each non-boot processor was started from the OF client
  57  * interface by prom_hold_cpus and is spinning on secondary_hold_spinloop.
  58  */
  59 static cpumask_var_t of_spin_mask;
  60
  61 /* Query where a cpu is now.  Return codes #defined in plpar_wrappers.h */
  62 int smp_query_cpu_stopped(unsigned int pcpu)
  63 {
  64         int cpu_status, status;
  65         int qcss_tok = rtas_token("query-cpu-stopped-state");
  66
  67         if (qcss_tok == RTAS_UNKNOWN_SERVICE) {
  68                 printk_once(KERN_INFO
  69                         "Firmware doesn't support query-cpu-stopped-state\n");
  70                 return QCSS_HARDWARE_ERROR;
  71         }
  72
  73         status = rtas_call(qcss_tok, 1, 2, &cpu_status, pcpu);
  74         if (status != 0) {
  75                 printk(KERN_ERR
  76                        "RTAS query-cpu-stopped-state failed: %i\n", status);
  77                 return status;
  78         }
  79
  80         return cpu_status;
  81 }
  82
  83 /**
  84  * smp_startup_cpu() - start the given cpu
  85  *
  86  * At boot time, there is nothing to do for primary threads which were
  87  * started from Open Firmware.  For anything else, call RTAS with the
  88  * appropriate start location.
  89  *
  90  * Returns:
  91  *      0       - failure
  92  *      1       - success
  93  */
  94 static inline int __devinit smp_startup_cpu(unsigned int lcpu)
  95 {
  96         int status;
  97         unsigned long start_here = __pa((u32)*((unsigned long *)
  98                                                generic_secondary_smp_init));
  99         unsigned int pcpu;
 100         int start_cpu;
 101
 102         if (cpumask_test_cpu(lcpu, of_spin_mask))
 103                 /* Already started by OF and sitting in spin loop */
 104                 return 1;
 105
 106         pcpu = get_hard_smp_processor_id(lcpu);
 107
 108         /* Check to see if the CPU out of FW already for kexec */
 109         if (smp_query_cpu_stopped(pcpu) == QCSS_NOT_STOPPED){
 110                 cpumask_set_cpu(lcpu, of_spin_mask);
 111                 return 1;
 112         }
 113
 114         /* Fixup atomic count: it exited inside IRQ handler. */
 115         task_thread_info(paca[lcpu].__current)->preempt_count   = 0;
 116 #ifdef CONFIG_HOTPLUG_CPU
 117         if (get_cpu_current_state(lcpu) == CPU_STATE_INACTIVE)
 118                 goto out;
 119 #endif
 120         /*
 121          * If the RTAS start-cpu token does not exist then presume the
 122          * cpu is already spinning.
 123          */
 124         start_cpu = rtas_token("start-cpu");
 125         if (start_cpu == RTAS_UNKNOWN_SERVICE)
 126                 return 1;
 127
 128         status = rtas_call(start_cpu, 3, 1, NULL, pcpu, start_here, pcpu);
 129         if (status != 0) {
 130                 printk(KERN_ERR "start-cpu failed: %i\n", status);
 131                 return 0;
 132         }
 133
 134 #ifdef CONFIG_HOTPLUG_CPU
 135 out:
 136 #endif
 137         return 1;
 138 }
 139
 140 static void __devinit smp_xics_setup_cpu(int cpu)
 141 {
 142         if (cpu != boot_cpuid)
 143                 xics_setup_cpu();
 144
 145         if (firmware_has_feature(FW_FEATURE_SPLPAR))
 146                 vpa_init(cpu);
 147
 148         cpumask_clear_cpu(cpu, of_spin_mask);
 149 #ifdef CONFIG_HOTPLUG_CPU
 150         set_cpu_current_state(cpu, CPU_STATE_ONLINE);
 151         set_default_offline_state(cpu);
 152 #endif
 153 }
 154
 155 static int __devinit smp_pSeries_kick_cpu(int nr)
 156 {
 157         BUG_ON(nr < 0 || nr >= NR_CPUS);
 158
 159         if (!smp_startup_cpu(nr))
 160                 return -ENOENT;
 161
 162         /*
 163          * The processor is currently spinning, waiting for the
 164          * cpu_start field to become non-zero After we set cpu_start,
 165          * the processor will continue on to secondary_start
 166          */
 167         paca[nr].cpu_start = 1;
 168 #ifdef CONFIG_HOTPLUG_CPU
 169         set_preferred_offline_state(nr, CPU_STATE_ONLINE);
 170
 171         if (get_cpu_current_state(nr) == CPU_STATE_INACTIVE) {
 172                 long rc;
 173                 unsigned long hcpuid;
 174
 175                 hcpuid = get_hard_smp_processor_id(nr);
 176                 rc = plpar_hcall_norets(H_PROD, hcpuid);
 177                 if (rc != H_SUCCESS)
 178                         printk(KERN_ERR "Error: Prod to wake up processor %d "
 179                                                 "Ret= %ld\n", nr, rc);
 180         }
 181 #endif
 182
 183         return 0;
 184 }
 185
 186 static int smp_pSeries_cpu_bootable(unsigned int nr)
 187 {
 188         /* Special case - we inhibit secondary thread startup
 189          * during boot if the user requests it.
 190          */
 191         if (system_state < SYSTEM_RUNNING && cpu_has_feature(CPU_FTR_SMT)) {
 192                 if (!smt_enabled_at_boot && cpu_thread_in_core(nr) != 0)
 193                         return 0;
 194                 if (smt_enabled_at_boot
 195                     && cpu_thread_in_core(nr) >= smt_enabled_at_boot)
 196                         return 0;
 197         }
 198
 199         return 1;
 200 }
 201
 202 static struct smp_ops_t pSeries_mpic_smp_ops = {
 203         .message_pass   = smp_mpic_message_pass,
 204         .probe          = smp_mpic_probe,
 205         .kick_cpu       = smp_pSeries_kick_cpu,
 206         .setup_cpu      = smp_mpic_setup_cpu,
 207 };
 208
 209 static struct smp_ops_t pSeries_xics_smp_ops = {
 210         .message_pass   = smp_muxed_ipi_message_pass,
 211         .cause_ipi      = NULL, /* Filled at runtime by xics_smp_probe() */
 212         .probe          = xics_smp_probe,
 213         .kick_cpu       = smp_pSeries_kick_cpu,
 214         .setup_cpu      = smp_xics_setup_cpu,
 215         .cpu_bootable   = smp_pSeries_cpu_bootable,
 216 };
 217
 218 /* This is called very early */
 219 static void __init smp_init_pseries(void)
 220 {
 221         int i;
 222
 223         pr_debug(" -> smp_init_pSeries()\n");
 224
 225         alloc_bootmem_cpumask_var(&of_spin_mask);
 226
 227         /* Mark threads which are still spinning in hold loops. */
 228         if (cpu_has_feature(CPU_FTR_SMT)) {
 229                 for_each_present_cpu(i) {
 230                         if (cpu_thread_in_core(i) == 0)
 231                                 cpumask_set_cpu(i, of_spin_mask);
 232                 }
 233         } else {
 234                 cpumask_copy(of_spin_mask, cpu_present_mask);
 235         }
 236
 237         cpumask_clear_cpu(boot_cpuid, of_spin_mask);
 238
 239         /* Non-lpar has additional take/give timebase */
 240         if (rtas_token("freeze-time-base") != RTAS_UNKNOWN_SERVICE) {
 241                 smp_ops->give_timebase = rtas_give_timebase;
 242                 smp_ops->take_timebase = rtas_take_timebase;
 243         }
 244
 245         pr_debug(" <- smp_init_pSeries()\n");
 246 }
 247
 248 void __init smp_init_pseries_mpic(void)
 249 {
 250         smp_ops = &pSeries_mpic_smp_ops;
 251
 252         smp_init_pseries();
 253 }
 254
 255 void __init smp_init_pseries_xics(void)
 256 {
 257         smp_ops = &pSeries_xics_smp_ops;
 258
 259         smp_init_pseries();
 260 }