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