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