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