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/vdso_datapage.h>
  42 #include <asm/cputhreads.h>
  43 #include <asm/xics.h>
  44 #include <asm/xive.h>
  45 #include <asm/dbell.h>
  46 #include <asm/plpar_wrappers.h>
  47 #include <asm/code-patching.h>
  48
  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 smp_startup_cpu(unsigned int lcpu)
  93 {
  94         int status;
  95         unsigned long start_here =
  96                         __pa(ppc_function_entry(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 smp_setup_cpu(int cpu)
 139 {
 140         if (xive_enabled())
 141                 xive_smp_setup_cpu();
 142         else 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 smp_pSeries_kick_cpu(int nr)
 156 {
 157         if (nr < 0 || nr >= nr_cpu_ids)
 158                 return -EINVAL;
 159
 160         if (!smp_startup_cpu(nr))
 161                 return -ENOENT;
 162
 163         /*
 164          * The processor is currently spinning, waiting for the
 165          * cpu_start field to become non-zero After we set cpu_start,
 166          * the processor will continue on to secondary_start
 167          */
 168         paca[nr].cpu_start = 1;
 169 #ifdef CONFIG_HOTPLUG_CPU
 170         set_preferred_offline_state(nr, CPU_STATE_ONLINE);
 171
 172         if (get_cpu_current_state(nr) == CPU_STATE_INACTIVE) {
 173                 long rc;
 174                 unsigned long hcpuid;
 175
 176                 hcpuid = get_hard_smp_processor_id(nr);
 177                 rc = plpar_hcall_norets(H_PROD, hcpuid);
 178                 if (rc != H_SUCCESS)
 179                         printk(KERN_ERR "Error: Prod to wake up processor %d "
 180                                                 "Ret= %ld\n", nr, rc);
 181         }
 182 #endif
 183
 184         return 0;
 185 }
 186
 187 static int pseries_smp_prepare_cpu(int cpu)
 188 {
 189         if (xive_enabled())
 190                 return xive_smp_prepare_cpu(cpu);
 191         return 0;
 192 }
 193
 194 static void smp_pseries_cause_ipi(int cpu)
 195 {
 196         /* POWER9 should not use this handler */
 197         if (doorbell_try_core_ipi(cpu))
 198                 return;
 199
 200         icp_ops->cause_ipi(cpu);
 201 }
 202
 203 static int pseries_cause_nmi_ipi(int cpu)
 204 {
 205         int hwcpu;
 206
 207         if (cpu == NMI_IPI_ALL_OTHERS) {
 208                 hwcpu = H_SIGNAL_SYS_RESET_ALL_OTHERS;
 209         } else {
 210                 if (cpu < 0) {
 211                         WARN_ONCE(true, "incorrect cpu parameter %d", cpu);
 212                         return 0;
 213                 }
 214
 215                 hwcpu = get_hard_smp_processor_id(cpu);
 216         }
 217
 218         if (plapr_signal_sys_reset(hwcpu) == H_SUCCESS)
 219                 return 1;
 220
 221         return 0;
 222 }
 223
 224 static __init void pSeries_smp_probe_xics(void)
 225 {
 226         xics_smp_probe();
 227
 228         if (cpu_has_feature(CPU_FTR_DBELL))
 229                 smp_ops->cause_ipi = smp_pseries_cause_ipi;
 230         else
 231                 smp_ops->cause_ipi = icp_ops->cause_ipi;
 232 }
 233
 234 static __init void pSeries_smp_probe(void)
 235 {
 236         if (xive_enabled())
 237                 /*
 238                  * Don't use P9 doorbells when XIVE is enabled. IPIs
 239                  * using MMIOs should be faster
 240                  */
 241                 xive_smp_probe();
 242         else
 243                 pSeries_smp_probe_xics();
 244 }
 245
 246 static struct smp_ops_t pseries_smp_ops = {
 247         .message_pass   = NULL, /* Use smp_muxed_ipi_message_pass */
 248         .cause_ipi      = NULL, /* Filled at runtime by pSeries_smp_probe() */
 249         .cause_nmi_ipi  = pseries_cause_nmi_ipi,
 250         .probe          = pSeries_smp_probe,
 251         .prepare_cpu    = pseries_smp_prepare_cpu,
 252         .kick_cpu       = smp_pSeries_kick_cpu,
 253         .setup_cpu      = smp_setup_cpu,
 254         .cpu_bootable   = smp_generic_cpu_bootable,
 255 };
 256
 257 /* This is called very early */
 258 void __init smp_init_pseries(void)
 259 {
 260         int i;
 261
 262         pr_debug(" -> smp_init_pSeries()\n");
 263         smp_ops = &pseries_smp_ops;
 264
 265         alloc_bootmem_cpumask_var(&of_spin_mask);
 266
 267         /*
 268          * Mark threads which are still spinning in hold loops
 269          *
 270          * We know prom_init will not have started them if RTAS supports
 271          * query-cpu-stopped-state.
 272          */
 273         if (rtas_token("query-cpu-stopped-state") == RTAS_UNKNOWN_SERVICE) {
 274                 if (cpu_has_feature(CPU_FTR_SMT)) {
 275                         for_each_present_cpu(i) {
 276                                 if (cpu_thread_in_core(i) == 0)
 277                                         cpumask_set_cpu(i, of_spin_mask);
 278                         }
 279                 } else
 280                         cpumask_copy(of_spin_mask, cpu_present_mask);
 281
 282                 cpumask_clear_cpu(boot_cpuid, of_spin_mask);
 283         }
 284
 285         /* Non-lpar has additional take/give timebase */
 286         if (rtas_token("freeze-time-base") != RTAS_UNKNOWN_SERVICE) {
 287                 smp_ops->give_timebase = rtas_give_timebase;
 288                 smp_ops->take_timebase = rtas_take_timebase;
 289         }
 290
 291         pr_debug(" <- smp_init_pSeries()\n");
 292 }