kernel/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 #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 /*
  60  * If we multiplex IPI mechanisms, store the appropriate XICS IPI mechanism here
  61  */
  62 static void  (*xics_cause_ipi)(int cpu, unsigned long data);
  63
  64 /* Query where a cpu is now.  Return codes #defined in plpar_wrappers.h */
  65 int smp_query_cpu_stopped(unsigned int pcpu)
  66 {
  67         int cpu_status, status;
  68         int qcss_tok = rtas_token("query-cpu-stopped-state");
  69
  70         if (qcss_tok == RTAS_UNKNOWN_SERVICE) {
  71                 printk_once(KERN_INFO
  72                         "Firmware doesn't support query-cpu-stopped-state\n");
  73                 return QCSS_HARDWARE_ERROR;
  74         }
  75
  76         status = rtas_call(qcss_tok, 1, 2, &cpu_status, pcpu);
  77         if (status != 0) {
  78                 printk(KERN_ERR
  79                        "RTAS query-cpu-stopped-state failed: %i\n", status);
  80                 return status;
  81         }
  82
  83         return cpu_status;
  84 }
  85
  86 /**
  87  * smp_startup_cpu() - start the given cpu
  88  *
  89  * At boot time, there is nothing to do for primary threads which were
  90  * started from Open Firmware.  For anything else, call RTAS with the
  91  * appropriate start location.
  92  *
  93  * Returns:
  94  *      0       - failure
  95  *      1       - success
  96  */
  97 static inline int smp_startup_cpu(unsigned int lcpu)
  98 {
  99         int status;
 100         unsigned long start_here =
 101                         __pa(ppc_function_entry(generic_secondary_smp_init));
 102         unsigned int pcpu;
 103         int start_cpu;
 104
 105         if (cpumask_test_cpu(lcpu, of_spin_mask))
 106                 /* Already started by OF and sitting in spin loop */
 107                 return 1;
 108
 109         pcpu = get_hard_smp_processor_id(lcpu);
 110
 111         /* Check to see if the CPU out of FW already for kexec */
 112         if (smp_query_cpu_stopped(pcpu) == QCSS_NOT_STOPPED){
 113                 cpumask_set_cpu(lcpu, of_spin_mask);
 114                 return 1;
 115         }
 116
 117         /* Fixup atomic count: it exited inside IRQ handler. */
 118         task_thread_info(paca[lcpu].__current)->preempt_count   = 0;
 119 #ifdef CONFIG_HOTPLUG_CPU
 120         if (get_cpu_current_state(lcpu) == CPU_STATE_INACTIVE)
 121                 goto out;
 122 #endif
 123         /*
 124          * If the RTAS start-cpu token does not exist then presume the
 125          * cpu is already spinning.
 126          */
 127         start_cpu = rtas_token("start-cpu");
 128         if (start_cpu == RTAS_UNKNOWN_SERVICE)
 129                 return 1;
 130
 131         status = rtas_call(start_cpu, 3, 1, NULL, pcpu, start_here, pcpu);
 132         if (status != 0) {
 133                 printk(KERN_ERR "start-cpu failed: %i\n", status);
 134                 return 0;
 135         }
 136
 137 #ifdef CONFIG_HOTPLUG_CPU
 138 out:
 139 #endif
 140         return 1;
 141 }
 142
 143 static void smp_xics_setup_cpu(int cpu)
 144 {
 145         if (cpu != boot_cpuid)
 146                 xics_setup_cpu();
 147         if (cpu_has_feature(CPU_FTR_DBELL))
 148                 doorbell_setup_this_cpu();
 149
 150         if (firmware_has_feature(FW_FEATURE_SPLPAR))
 151                 vpa_init(cpu);
 152
 153         cpumask_clear_cpu(cpu, of_spin_mask);
 154 #ifdef CONFIG_HOTPLUG_CPU
 155         set_cpu_current_state(cpu, CPU_STATE_ONLINE);
 156         set_default_offline_state(cpu);
 157 #endif
 158 }
 159
 160 static int smp_pSeries_kick_cpu(int nr)
 161 {
 162         BUG_ON(nr < 0 || nr >= NR_CPUS);
 163
 164         if (!smp_startup_cpu(nr))
 165                 return -ENOENT;
 166
 167         /*
 168          * The processor is currently spinning, waiting for the
 169          * cpu_start field to become non-zero After we set cpu_start,
 170          * the processor will continue on to secondary_start
 171          */
 172         paca[nr].cpu_start = 1;
 173 #ifdef CONFIG_HOTPLUG_CPU
 174         set_preferred_offline_state(nr, CPU_STATE_ONLINE);
 175
 176         if (get_cpu_current_state(nr) == CPU_STATE_INACTIVE) {
 177                 long rc;
 178                 unsigned long hcpuid;
 179
 180                 hcpuid = get_hard_smp_processor_id(nr);
 181                 rc = plpar_hcall_norets(H_PROD, hcpuid);
 182                 if (rc != H_SUCCESS)
 183                         printk(KERN_ERR "Error: Prod to wake up processor %d "
 184                                                 "Ret= %ld\n", nr, rc);
 185         }
 186 #endif
 187
 188         return 0;
 189 }
 190
 191 /* Only used on systems that support multiple IPI mechanisms */
 192 static void pSeries_cause_ipi_mux(int cpu, unsigned long data)
 193 {
 194         if (cpumask_test_cpu(cpu, cpu_sibling_mask(smp_processor_id())))
 195                 doorbell_cause_ipi(cpu, data);
 196         else
 197                 xics_cause_ipi(cpu, data);
 198 }
 199
 200 static __init void pSeries_smp_probe(void)
 201 {
 202         xics_smp_probe();
 203
 204         if (cpu_has_feature(CPU_FTR_DBELL)) {
 205                 xics_cause_ipi = smp_ops->cause_ipi;
 206                 smp_ops->cause_ipi = pSeries_cause_ipi_mux;
 207         }
 208 }
 209
 210 static struct smp_ops_t pSeries_mpic_smp_ops = {
 211         .message_pass   = smp_mpic_message_pass,
 212         .probe          = smp_mpic_probe,
 213         .kick_cpu       = smp_pSeries_kick_cpu,
 214         .setup_cpu      = smp_mpic_setup_cpu,
 215 };
 216
 217 static struct smp_ops_t pSeries_xics_smp_ops = {
 218         .message_pass   = NULL, /* Use smp_muxed_ipi_message_pass */
 219         .cause_ipi      = NULL, /* Filled at runtime by pSeries_smp_probe() */
 220         .probe          = pSeries_smp_probe,
 221         .kick_cpu       = smp_pSeries_kick_cpu,
 222         .setup_cpu      = smp_xics_setup_cpu,
 223         .cpu_bootable   = smp_generic_cpu_bootable,
 224 };
 225
 226 /* This is called very early */
 227 static void __init smp_init_pseries(void)
 228 {
 229         int i;
 230
 231         pr_debug(" -> smp_init_pSeries()\n");
 232
 233         alloc_bootmem_cpumask_var(&of_spin_mask);
 234
 235         /*
 236          * Mark threads which are still spinning in hold loops
 237          *
 238          * We know prom_init will not have started them if RTAS supports
 239          * query-cpu-stopped-state.
 240          */
 241         if (rtas_token("query-cpu-stopped-state") == RTAS_UNKNOWN_SERVICE) {
 242                 if (cpu_has_feature(CPU_FTR_SMT)) {
 243                         for_each_present_cpu(i) {
 244                                 if (cpu_thread_in_core(i) == 0)
 245                                         cpumask_set_cpu(i, of_spin_mask);
 246                         }
 247                 } else
 248                         cpumask_copy(of_spin_mask, cpu_present_mask);
 249
 250                 cpumask_clear_cpu(boot_cpuid, of_spin_mask);
 251         }
 252
 253         /* Non-lpar has additional take/give timebase */
 254         if (rtas_token("freeze-time-base") != RTAS_UNKNOWN_SERVICE) {
 255                 smp_ops->give_timebase = rtas_give_timebase;
 256                 smp_ops->take_timebase = rtas_take_timebase;
 257         }
 258
 259         pr_debug(" <- smp_init_pSeries()\n");
 260 }
 261
 262 void __init smp_init_pseries_mpic(void)
 263 {
 264         smp_ops = &pSeries_mpic_smp_ops;
 265
 266         smp_init_pseries();
 267 }
 268
 269 void __init smp_init_pseries_xics(void)
 270 {
 271         smp_ops = &pSeries_xics_smp_ops;
 272
 273         smp_init_pseries();
 274 }