arch/powerpc/platforms/pseries/hotplug-cpu.c

   1 /*
   2  * pseries CPU Hotplug infrastructure.
   3  *
   4  * Split out from arch/powerpc/platforms/pseries/setup.c
   5  *  arch/powerpc/kernel/rtas.c, and arch/powerpc/platforms/pseries/smp.c
   6  *
   7  * Peter Bergner, IBM   March 2001.
   8  * Copyright (C) 2001 IBM.
   9  * Dave Engebretsen, Peter Bergner, and
  10  * Mike Corrigan {engebret|bergner|mikec}@us.ibm.com
  11  * Plus various changes from other IBM teams...
  12  *
  13  * Copyright (C) 2006 Michael Ellerman, IBM Corporation
  14  *
  15  *      This program is free software; you can redistribute it and/or
  16  *      modify it under the terms of the GNU General Public License
  17  *      as published by the Free Software Foundation; either version
  18  *      2 of the License, or (at your option) any later version.
  19  */
  20
  21 #include <linux/kernel.h>
  22 #include <linux/delay.h>
  23 #include <linux/cpu.h>
  24 #include <asm/system.h>
  25 #include <asm/prom.h>
  26 #include <asm/rtas.h>
  27 #include <asm/firmware.h>
  28 #include <asm/machdep.h>
  29 #include <asm/vdso_datapage.h>
  30 #include <asm/pSeries_reconfig.h>
  31 #include "xics.h"
  32
  33 /* This version can't take the spinlock, because it never returns */
  34 static struct rtas_args rtas_stop_self_args = {
  35         .token = RTAS_UNKNOWN_SERVICE,
  36         .nargs = 0,
  37         .nret = 1,
  38         .rets = &rtas_stop_self_args.args[0],
  39 };
  40
  41 static void rtas_stop_self(void)
  42 {
  43         struct rtas_args *args = &rtas_stop_self_args;
  44
  45         local_irq_disable();
  46
  47         BUG_ON(args->token == RTAS_UNKNOWN_SERVICE);
  48
  49         printk("cpu %u (hwid %u) Ready to die...\n",
  50                smp_processor_id(), hard_smp_processor_id());
  51         enter_rtas(__pa(args));
  52
  53         panic("Alas, I survived.\n");
  54 }
  55
  56 static void pseries_mach_cpu_die(void)
  57 {
  58         local_irq_disable();
  59         idle_task_exit();
  60         xics_teardown_cpu(0);
  61         rtas_stop_self();
  62         /* Should never get here... */
  63         BUG();
  64         for(;;);
  65 }
  66
  67 static int qcss_tok;    /* query-cpu-stopped-state token */
  68
  69 /* Get state of physical CPU.
  70  * Return codes:
  71  *      0       - The processor is in the RTAS stopped state
  72  *      1       - stop-self is in progress
  73  *      2       - The processor is not in the RTAS stopped state
  74  *      -1      - Hardware Error
  75  *      -2      - Hardware Busy, Try again later.
  76  */
  77 static int query_cpu_stopped(unsigned int pcpu)
  78 {
  79         int cpu_status, status;
  80
  81         status = rtas_call(qcss_tok, 1, 2, &cpu_status, pcpu);
  82         if (status != 0) {
  83                 printk(KERN_ERR
  84                        "RTAS query-cpu-stopped-state failed: %i\n", status);
  85                 return status;
  86         }
  87
  88         return cpu_status;
  89 }
  90
  91 static int pseries_cpu_disable(void)
  92 {
  93         int cpu = smp_processor_id();
  94
  95         cpu_clear(cpu, cpu_online_map);
  96         vdso_data->processorCount--;
  97
  98         /*fix boot_cpuid here*/
  99         if (cpu == boot_cpuid)
 100                 boot_cpuid = any_online_cpu(cpu_online_map);
 101
 102         /* FIXME: abstract this to not be platform specific later on */
 103         xics_migrate_irqs_away();
 104         return 0;
 105 }
 106
 107 static void pseries_cpu_die(unsigned int cpu)
 108 {
 109         int tries;
 110         int cpu_status;
 111         unsigned int pcpu = get_hard_smp_processor_id(cpu);
 112
 113         for (tries = 0; tries < 25; tries++) {
 114                 cpu_status = query_cpu_stopped(pcpu);
 115                 if (cpu_status == 0 || cpu_status == -1)
 116                         break;
 117                 msleep(200);
 118         }
 119         if (cpu_status != 0) {
 120                 printk("Querying DEAD? cpu %i (%i) shows %i\n",
 121                        cpu, pcpu, cpu_status);
 122         }
 123
 124         /* Isolation and deallocation are definatly done by
 125          * drslot_chrp_cpu.  If they were not they would be
 126          * done here.  Change isolate state to Isolate and
 127          * change allocation-state to Unusable.
 128          */
 129         paca[cpu].cpu_start = 0;
 130 }
 131
 132 /*
 133  * Update cpu_present_map and paca(s) for a new cpu node.  The wrinkle
 134  * here is that a cpu device node may represent up to two logical cpus
 135  * in the SMT case.  We must honor the assumption in other code that
 136  * the logical ids for sibling SMT threads x and y are adjacent, such
 137  * that x^1 == y and y^1 == x.
 138  */
 139 static int pseries_add_processor(struct device_node *np)
 140 {
 141         unsigned int cpu;
 142         cpumask_t candidate_map, tmp = CPU_MASK_NONE;
 143         int err = -ENOSPC, len, nthreads, i;
 144         const u32 *intserv;
 145
 146         intserv = of_get_property(np, "ibm,ppc-interrupt-server#s", &len);
 147         if (!intserv)
 148                 return 0;
 149
 150         nthreads = len / sizeof(u32);
 151         for (i = 0; i < nthreads; i++)
 152                 cpu_set(i, tmp);
 153
 154         lock_cpu_hotplug();
 155
 156         BUG_ON(!cpus_subset(cpu_present_map, cpu_possible_map));
 157
 158         /* Get a bitmap of unoccupied slots. */
 159         cpus_xor(candidate_map, cpu_possible_map, cpu_present_map);
 160         if (cpus_empty(candidate_map)) {
 161                 /* If we get here, it most likely means that NR_CPUS is
 162                  * less than the partition's max processors setting.
 163                  */
 164                 printk(KERN_ERR "Cannot add cpu %s; this system configuration"
 165                        " supports %d logical cpus.\n", np->full_name,
 166                        cpus_weight(cpu_possible_map));
 167                 goto out_unlock;
 168         }
 169
 170         while (!cpus_empty(tmp))
 171                 if (cpus_subset(tmp, candidate_map))
 172                         /* Found a range where we can insert the new cpu(s) */
 173                         break;
 174                 else
 175                         cpus_shift_left(tmp, tmp, nthreads);
 176
 177         if (cpus_empty(tmp)) {
 178                 printk(KERN_ERR "Unable to find space in cpu_present_map for"
 179                        " processor %s with %d thread(s)\n", np->name,
 180                        nthreads);
 181                 goto out_unlock;
 182         }
 183
 184         for_each_cpu_mask(cpu, tmp) {
 185                 BUG_ON(cpu_isset(cpu, cpu_present_map));
 186                 cpu_set(cpu, cpu_present_map);
 187                 set_hard_smp_processor_id(cpu, *intserv++);
 188         }
 189         err = 0;
 190 out_unlock:
 191         unlock_cpu_hotplug();
 192         return err;
 193 }
 194
 195 /*
 196  * Update the present map for a cpu node which is going away, and set
 197  * the hard id in the paca(s) to -1 to be consistent with boot time
 198  * convention for non-present cpus.
 199  */
 200 static void pseries_remove_processor(struct device_node *np)
 201 {
 202         unsigned int cpu;
 203         int len, nthreads, i;
 204         const u32 *intserv;
 205
 206         intserv = of_get_property(np, "ibm,ppc-interrupt-server#s", &len);
 207         if (!intserv)
 208                 return;
 209
 210         nthreads = len / sizeof(u32);
 211
 212         lock_cpu_hotplug();
 213         for (i = 0; i < nthreads; i++) {
 214                 for_each_present_cpu(cpu) {
 215                         if (get_hard_smp_processor_id(cpu) != intserv[i])
 216                                 continue;
 217                         BUG_ON(cpu_online(cpu));
 218                         cpu_clear(cpu, cpu_present_map);
 219                         set_hard_smp_processor_id(cpu, -1);
 220                         break;
 221                 }
 222                 if (cpu == NR_CPUS)
 223                         printk(KERN_WARNING "Could not find cpu to remove "
 224                                "with physical id 0x%x\n", intserv[i]);
 225         }
 226         unlock_cpu_hotplug();
 227 }
 228
 229 static int pseries_smp_notifier(struct notifier_block *nb,
 230                                 unsigned long action, void *node)
 231 {
 232         int err = NOTIFY_OK;
 233
 234         switch (action) {
 235         case PSERIES_RECONFIG_ADD:
 236                 if (pseries_add_processor(node))
 237                         err = NOTIFY_BAD;
 238                 break;
 239         case PSERIES_RECONFIG_REMOVE:
 240                 pseries_remove_processor(node);
 241                 break;
 242         default:
 243                 err = NOTIFY_DONE;
 244                 break;
 245         }
 246         return err;
 247 }
 248
 249 static struct notifier_block pseries_smp_nb = {
 250         .notifier_call = pseries_smp_notifier,
 251 };
 252
 253 static int __init pseries_cpu_hotplug_init(void)
 254 {
 255         struct device_node *np;
 256         const char *typep;
 257
 258         for_each_node_by_name(np, "interrupt-controller") {
 259                 typep = of_get_property(np, "compatible", NULL);
 260                 if (strstr(typep, "open-pic")) {
 261                         of_node_put(np);
 262
 263                         printk(KERN_INFO "CPU Hotplug not supported on "
 264                                 "systems using MPIC\n");
 265                         return 0;
 266                 }
 267         }
 268
 269         rtas_stop_self_args.token = rtas_token("stop-self");
 270         qcss_tok = rtas_token("query-cpu-stopped-state");
 271
 272         if (rtas_stop_self_args.token == RTAS_UNKNOWN_SERVICE ||
 273                         qcss_tok == RTAS_UNKNOWN_SERVICE) {
 274                 printk(KERN_INFO "CPU Hotplug not supported by firmware "
 275                                 "- disabling.\n");
 276                 return 0;
 277         }
 278
 279         ppc_md.cpu_die = pseries_mach_cpu_die;
 280         smp_ops->cpu_disable = pseries_cpu_disable;
 281         smp_ops->cpu_die = pseries_cpu_die;
 282
 283         /* Processors can be added/removed only on LPAR */
 284         if (firmware_has_feature(FW_FEATURE_LPAR))
 285                 pSeries_reconfig_notifier_register(&pseries_smp_nb);
 286
 287         return 0;
 288 }
 289 arch_initcall(pseries_cpu_hotplug_init);