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/dbell.h>
  45 #include <asm/plpar_wrappers.h>
  46 #include <asm/code-patching.h>
  47
  48 #include "pseries.h"
  49 #include "offline_states.h"
  50
  51
  52 /*
  53  * The Primary thread of each non-boot processor was started from the OF client
  54  * interface by prom_hold_cpus and is spinning on secondary_hold_spinloop.
  55  */
  56 static cpumask_var_t of_spin_mask;
  57
  58 /* Query where a cpu is now.  Return codes #defined in plpar_wrappers.h */
  59 int smp_query_cpu_stopped(unsigned int pcpu)
  60 {
  61         int cpu_status, status;
  62         int qcss_tok = rtas_token("query-cpu-stopped-state");
  63
  64         if (qcss_tok == RTAS_UNKNOWN_SERVICE) {
  65                 printk_once(KERN_INFO
  66                         "Firmware doesn't support query-cpu-stopped-state\n");
  67                 return QCSS_HARDWARE_ERROR;
  68         }
  69
  70         status = rtas_call(qcss_tok, 1, 2, &cpu_status, pcpu);
  71         if (status != 0) {
  72                 printk(KERN_ERR
  73                        "RTAS query-cpu-stopped-state failed: %i\n", status);
  74                 return status;
  75         }
  76
  77         return cpu_status;
  78 }
  79
  80 /**
  81  * smp_startup_cpu() - start the given cpu
  82  *
  83  * At boot time, there is nothing to do for primary threads which were
  84  * started from Open Firmware.  For anything else, call RTAS with the
  85  * appropriate start location.
  86  *
  87  * Returns:
  88  *      0       - failure
  89  *      1       - success
  90  */
  91 static inline int smp_startup_cpu(unsigned int lcpu)
  92 {
  93         int status;
  94         unsigned long start_here =
  95                         __pa(ppc_function_entry(generic_secondary_smp_init));
  96         unsigned int pcpu;
  97         int start_cpu;
  98
  99         if (cpumask_test_cpu(lcpu, of_spin_mask))
 100                 /* Already started by OF and sitting in spin loop */
 101                 return 1;
 102
 103         pcpu = get_hard_smp_processor_id(lcpu);
 104
 105         /* Check to see if the CPU out of FW already for kexec */
 106         if (smp_query_cpu_stopped(pcpu) == QCSS_NOT_STOPPED){
 107                 cpumask_set_cpu(lcpu, of_spin_mask);
 108                 return 1;
 109         }
 110
 111         /* Fixup atomic count: it exited inside IRQ handler. */
 112         task_thread_info(paca[lcpu].__current)->preempt_count   = 0;
 113 #ifdef CONFIG_HOTPLUG_CPU
 114         if (get_cpu_current_state(lcpu) == CPU_STATE_INACTIVE)
 115                 goto out;
 116 #endif
 117         /*
 118          * If the RTAS start-cpu token does not exist then presume the
 119          * cpu is already spinning.
 120          */
 121         start_cpu = rtas_token("start-cpu");
 122         if (start_cpu == RTAS_UNKNOWN_SERVICE)
 123                 return 1;
 124
 125         status = rtas_call(start_cpu, 3, 1, NULL, pcpu, start_here, pcpu);
 126         if (status != 0) {
 127                 printk(KERN_ERR "start-cpu failed: %i\n", status);
 128                 return 0;
 129         }
 130
 131 #ifdef CONFIG_HOTPLUG_CPU
 132 out:
 133 #endif
 134         return 1;
 135 }
 136
 137 static void smp_setup_cpu(int cpu)
 138 {
 139         if (cpu != boot_cpuid)
 140                 xics_setup_cpu();
 141
 142         if (firmware_has_feature(FW_FEATURE_SPLPAR))
 143                 vpa_init(cpu);
 144
 145         cpumask_clear_cpu(cpu, of_spin_mask);
 146 #ifdef CONFIG_HOTPLUG_CPU
 147         set_cpu_current_state(cpu, CPU_STATE_ONLINE);
 148         set_default_offline_state(cpu);
 149 #endif
 150 }
 151
 152 static int smp_pSeries_kick_cpu(int nr)
 153 {
 154         if (nr < 0 || nr >= nr_cpu_ids)
 155                 return -EINVAL;
 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 void smp_pseries_cause_ipi(int cpu)
 185 {
 186         /* POWER9 should not use this handler */
 187         if (doorbell_try_core_ipi(cpu))
 188                 return;
 189
 190         icp_ops->cause_ipi(cpu);
 191 }
 192
 193 static int pseries_cause_nmi_ipi(int cpu)
 194 {
 195         int hwcpu;
 196
 197         if (cpu == NMI_IPI_ALL_OTHERS) {
 198                 hwcpu = H_SIGNAL_SYS_RESET_ALL_OTHERS;
 199         } else {
 200                 if (cpu < 0) {
 201                         WARN_ONCE(true, "incorrect cpu parameter %d", cpu);
 202                         return 0;
 203                 }
 204
 205                 hwcpu = get_hard_smp_processor_id(cpu);
 206         }
 207
 208         if (plapr_signal_sys_reset(hwcpu) == H_SUCCESS)
 209                 return 1;
 210
 211         return 0;
 212 }
 213
 214 static __init void pSeries_smp_probe(void)
 215 {
 216         xics_smp_probe();
 217
 218         if (cpu_has_feature(CPU_FTR_DBELL))
 219                 smp_ops->cause_ipi = smp_pseries_cause_ipi;
 220         else
 221                 smp_ops->cause_ipi = icp_ops->cause_ipi;
 222 }
 223
 224 static struct smp_ops_t pseries_smp_ops = {
 225         .message_pass   = NULL, /* Use smp_muxed_ipi_message_pass */
 226         .cause_ipi      = NULL, /* Filled at runtime by pSeries_smp_probe() */
 227         .cause_nmi_ipi  = pseries_cause_nmi_ipi,
 228         .probe          = pSeries_smp_probe,
 229         .kick_cpu       = smp_pSeries_kick_cpu,
 230         .setup_cpu      = smp_setup_cpu,
 231         .cpu_bootable   = smp_generic_cpu_bootable,
 232 };
 233
 234 /* This is called very early */
 235 void __init smp_init_pseries(void)
 236 {
 237         int i;
 238
 239         pr_debug(" -> smp_init_pSeries()\n");
 240         smp_ops = &pseries_smp_ops;
 241
 242         alloc_bootmem_cpumask_var(&of_spin_mask);
 243
 244         /*
 245          * Mark threads which are still spinning in hold loops
 246          *
 247          * We know prom_init will not have started them if RTAS supports
 248          * query-cpu-stopped-state.
 249          */
 250         if (rtas_token("query-cpu-stopped-state") == RTAS_UNKNOWN_SERVICE) {
 251                 if (cpu_has_feature(CPU_FTR_SMT)) {
 252                         for_each_present_cpu(i) {
 253                                 if (cpu_thread_in_core(i) == 0)
 254                                         cpumask_set_cpu(i, of_spin_mask);
 255                         }
 256                 } else
 257                         cpumask_copy(of_spin_mask, cpu_present_mask);
 258
 259                 cpumask_clear_cpu(boot_cpuid, of_spin_mask);
 260         }
 261
 262         /* Non-lpar has additional take/give timebase */
 263         if (rtas_token("freeze-time-base") != RTAS_UNKNOWN_SERVICE) {
 264                 smp_ops->give_timebase = rtas_give_timebase;
 265                 smp_ops->take_timebase = rtas_take_timebase;
 266         }
 267
 268         pr_debug(" <- smp_init_pSeries()\n");
 269 }