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 #include "plpar_wrappers.h"
  33
  34 /* This version can't take the spinlock, because it never returns */
  35 static struct rtas_args rtas_stop_self_args = {
  36         .token = RTAS_UNKNOWN_SERVICE,
  37         .nargs = 0,
  38         .nret = 1,
  39         .rets = &rtas_stop_self_args.args[0],
  40 };
  41
  42 static void rtas_stop_self(void)
  43 {
  44         struct rtas_args *args = &rtas_stop_self_args;
  45
  46         local_irq_disable();
  47
  48         BUG_ON(args->token == RTAS_UNKNOWN_SERVICE);
  49
  50         printk("cpu %u (hwid %u) Ready to die...\n",
  51                smp_processor_id(), hard_smp_processor_id());
  52         enter_rtas(__pa(args));
  53
  54         panic("Alas, I survived.\n");
  55 }
  56
  57 static void pseries_mach_cpu_die(void)
  58 {
  59         local_irq_disable();
  60         idle_task_exit();
  61         xics_teardown_cpu();
  62         unregister_slb_shadow(hard_smp_processor_id(), __pa(get_slb_shadow()));
  63         rtas_stop_self();
  64         /* Should never get here... */
  65         BUG();
  66         for(;;);
  67 }
  68
  69 static int qcss_tok;    /* query-cpu-stopped-state token */
  70
  71 /* Get state of physical CPU.
  72  * Return codes:
  73  *      0       - The processor is in the RTAS stopped state
  74  *      1       - stop-self is in progress
  75  *      2       - The processor is not in the RTAS stopped state
  76  *      -1      - Hardware Error
  77  *      -2      - Hardware Busy, Try again later.
  78  */
  79 static int query_cpu_stopped(unsigned int pcpu)
  80 {
  81         int cpu_status, status;
  82
  83         status = rtas_call(qcss_tok, 1, 2, &cpu_status, pcpu);
  84         if (status != 0) {
  85                 printk(KERN_ERR
  86                        "RTAS query-cpu-stopped-state failed: %i\n", status);
  87                 return status;
  88         }
  89
  90         return cpu_status;
  91 }
  92
  93 static int pseries_cpu_disable(void)
  94 {
  95         int cpu = smp_processor_id();
  96
  97         set_cpu_online(cpu, false);
  98         vdso_data->processorCount--;
  99
 100         /*fix boot_cpuid here*/
 101         if (cpu == boot_cpuid)
 102                 boot_cpuid = any_online_cpu(cpu_online_map);
 103
 104         /* FIXME: abstract this to not be platform specific later on */
 105         xics_migrate_irqs_away();
 106         return 0;
 107 }
 108
 109 static void pseries_cpu_die(unsigned int cpu)
 110 {
 111         int tries;
 112         int cpu_status;
 113         unsigned int pcpu = get_hard_smp_processor_id(cpu);
 114
 115         for (tries = 0; tries < 25; tries++) {
 116                 cpu_status = query_cpu_stopped(pcpu);
 117                 if (cpu_status == 0 || cpu_status == -1)
 118                         break;
 119                 cpu_relax();
 120         }
 121         if (cpu_status != 0) {
 122                 printk("Querying DEAD? cpu %i (%i) shows %i\n",
 123                        cpu, pcpu, cpu_status);
 124         }
 125
 126         /* Isolation and deallocation are definatly done by
 127          * drslot_chrp_cpu.  If they were not they would be
 128          * done here.  Change isolate state to Isolate and
 129          * change allocation-state to Unusable.
 130          */
 131         paca[cpu].cpu_start = 0;
 132 }
 133
 134 /*
 135  * Update cpu_present_map and paca(s) for a new cpu node.  The wrinkle
 136  * here is that a cpu device node may represent up to two logical cpus
 137  * in the SMT case.  We must honor the assumption in other code that
 138  * the logical ids for sibling SMT threads x and y are adjacent, such
 139  * that x^1 == y and y^1 == x.
 140  */
 141 static int pseries_add_processor(struct device_node *np)
 142 {
 143         unsigned int cpu;
 144         cpumask_t candidate_map, tmp = CPU_MASK_NONE;
 145         int err = -ENOSPC, len, nthreads, i;
 146         const u32 *intserv;
 147
 148         intserv = of_get_property(np, "ibm,ppc-interrupt-server#s", &len);
 149         if (!intserv)
 150                 return 0;
 151
 152         nthreads = len / sizeof(u32);
 153         for (i = 0; i < nthreads; i++)
 154                 cpu_set(i, tmp);
 155
 156         cpu_maps_update_begin();
 157
 158         BUG_ON(!cpus_subset(cpu_present_map, cpu_possible_map));
 159
 160         /* Get a bitmap of unoccupied slots. */
 161         cpus_xor(candidate_map, cpu_possible_map, cpu_present_map);
 162         if (cpus_empty(candidate_map)) {
 163                 /* If we get here, it most likely means that NR_CPUS is
 164                  * less than the partition's max processors setting.
 165                  */
 166                 printk(KERN_ERR "Cannot add cpu %s; this system configuration"
 167                        " supports %d logical cpus.\n", np->full_name,
 168                        cpus_weight(cpu_possible_map));
 169                 goto out_unlock;
 170         }
 171
 172         while (!cpus_empty(tmp))
 173                 if (cpus_subset(tmp, candidate_map))
 174                         /* Found a range where we can insert the new cpu(s) */
 175                         break;
 176                 else
 177                         cpus_shift_left(tmp, tmp, nthreads);
 178
 179         if (cpus_empty(tmp)) {
 180                 printk(KERN_ERR "Unable to find space in cpu_present_map for"
 181                        " processor %s with %d thread(s)\n", np->name,
 182                        nthreads);
 183                 goto out_unlock;
 184         }
 185
 186         for_each_cpu_mask(cpu, tmp) {
 187                 BUG_ON(cpu_isset(cpu, cpu_present_map));
 188                 set_cpu_present(cpu, true);
 189                 set_hard_smp_processor_id(cpu, *intserv++);
 190         }
 191         err = 0;
 192 out_unlock:
 193         cpu_maps_update_done();
 194         return err;
 195 }
 196
 197 /*
 198  * Update the present map for a cpu node which is going away, and set
 199  * the hard id in the paca(s) to -1 to be consistent with boot time
 200  * convention for non-present cpus.
 201  */
 202 static void pseries_remove_processor(struct device_node *np)
 203 {
 204         unsigned int cpu;
 205         int len, nthreads, i;
 206         const u32 *intserv;
 207
 208         intserv = of_get_property(np, "ibm,ppc-interrupt-server#s", &len);
 209         if (!intserv)
 210                 return;
 211
 212         nthreads = len / sizeof(u32);
 213
 214         cpu_maps_update_begin();
 215         for (i = 0; i < nthreads; i++) {
 216                 for_each_present_cpu(cpu) {
 217                         if (get_hard_smp_processor_id(cpu) != intserv[i])
 218                                 continue;
 219                         BUG_ON(cpu_online(cpu));
 220                         set_cpu_present(cpu, false);
 221                         set_hard_smp_processor_id(cpu, -1);
 222                         break;
 223                 }
 224                 if (cpu == NR_CPUS)
 225                         printk(KERN_WARNING "Could not find cpu to remove "
 226                                "with physical id 0x%x\n", intserv[i]);
 227         }
 228         cpu_maps_update_done();
 229 }
 230
 231 static int pseries_smp_notifier(struct notifier_block *nb,
 232                                 unsigned long action, void *node)
 233 {
 234         int err = NOTIFY_OK;
 235
 236         switch (action) {
 237         case PSERIES_RECONFIG_ADD:
 238                 if (pseries_add_processor(node))
 239                         err = NOTIFY_BAD;
 240                 break;
 241         case PSERIES_RECONFIG_REMOVE:
 242                 pseries_remove_processor(node);
 243                 break;
 244         default:
 245                 err = NOTIFY_DONE;
 246                 break;
 247         }
 248         return err;
 249 }
 250
 251 static struct notifier_block pseries_smp_nb = {
 252         .notifier_call = pseries_smp_notifier,
 253 };
 254
 255 static int __init pseries_cpu_hotplug_init(void)
 256 {
 257         struct device_node *np;
 258         const char *typep;
 259
 260         for_each_node_by_name(np, "interrupt-controller") {
 261                 typep = of_get_property(np, "compatible", NULL);
 262                 if (strstr(typep, "open-pic")) {
 263                         of_node_put(np);
 264
 265                         printk(KERN_INFO "CPU Hotplug not supported on "
 266                                 "systems using MPIC\n");
 267                         return 0;
 268                 }
 269         }
 270
 271         rtas_stop_self_args.token = rtas_token("stop-self");
 272         qcss_tok = rtas_token("query-cpu-stopped-state");
 273
 274         if (rtas_stop_self_args.token == RTAS_UNKNOWN_SERVICE ||
 275                         qcss_tok == RTAS_UNKNOWN_SERVICE) {
 276                 printk(KERN_INFO "CPU Hotplug not supported by firmware "
 277                                 "- disabling.\n");
 278                 return 0;
 279         }
 280
 281         ppc_md.cpu_die = pseries_mach_cpu_die;
 282         smp_ops->cpu_disable = pseries_cpu_disable;
 283         smp_ops->cpu_die = pseries_cpu_die;
 284
 285         /* Processors can be added/removed only on LPAR */
 286         if (firmware_has_feature(FW_FEATURE_LPAR))
 287                 pSeries_reconfig_notifier_register(&pseries_smp_nb);
 288
 289         return 0;
 290 }
 291 arch_initcall(pseries_cpu_hotplug_init);