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/interrupt.h>
  23 #include <linux/delay.h>
  24 #include <linux/sched.h>        /* for idle_task_exit */
  25 #include <linux/cpu.h>
  26 #include <linux/of.h>
  27 #include <asm/prom.h>
  28 #include <asm/rtas.h>
  29 #include <asm/firmware.h>
  30 #include <asm/machdep.h>
  31 #include <asm/vdso_datapage.h>
  32 #include <asm/xics.h>
  33 #include <asm/plpar_wrappers.h>
  34
  35 #include "offline_states.h"
  36
  37 /* This version can't take the spinlock, because it never returns */
  38 static struct rtas_args rtas_stop_self_args = {
  39         .token = RTAS_UNKNOWN_SERVICE,
  40         .nargs = 0,
  41         .nret = 1,
  42         .rets = &rtas_stop_self_args.args[0],
  43 };
  44
  45 static DEFINE_PER_CPU(enum cpu_state_vals, preferred_offline_state) =
  46                                                         CPU_STATE_OFFLINE;
  47 static DEFINE_PER_CPU(enum cpu_state_vals, current_state) = CPU_STATE_OFFLINE;
  48
  49 static enum cpu_state_vals default_offline_state = CPU_STATE_OFFLINE;
  50
  51 static int cede_offline_enabled __read_mostly = 1;
  52
  53 /*
  54  * Enable/disable cede_offline when available.
  55  */
  56 static int __init setup_cede_offline(char *str)
  57 {
  58         if (!strcmp(str, "off"))
  59                 cede_offline_enabled = 0;
  60         else if (!strcmp(str, "on"))
  61                 cede_offline_enabled = 1;
  62         else
  63                 return 0;
  64         return 1;
  65 }
  66
  67 __setup("cede_offline=", setup_cede_offline);
  68
  69 enum cpu_state_vals get_cpu_current_state(int cpu)
  70 {
  71         return per_cpu(current_state, cpu);
  72 }
  73
  74 void set_cpu_current_state(int cpu, enum cpu_state_vals state)
  75 {
  76         per_cpu(current_state, cpu) = state;
  77 }
  78
  79 enum cpu_state_vals get_preferred_offline_state(int cpu)
  80 {
  81         return per_cpu(preferred_offline_state, cpu);
  82 }
  83
  84 void set_preferred_offline_state(int cpu, enum cpu_state_vals state)
  85 {
  86         per_cpu(preferred_offline_state, cpu) = state;
  87 }
  88
  89 void set_default_offline_state(int cpu)
  90 {
  91         per_cpu(preferred_offline_state, cpu) = default_offline_state;
  92 }
  93
  94 static void rtas_stop_self(void)
  95 {
  96         struct rtas_args *args = &rtas_stop_self_args;
  97
  98         local_irq_disable();
  99
 100         BUG_ON(args->token == RTAS_UNKNOWN_SERVICE);
 101
 102         printk("cpu %u (hwid %u) Ready to die...\n",
 103                smp_processor_id(), hard_smp_processor_id());
 104         enter_rtas(__pa(args));
 105
 106         panic("Alas, I survived.\n");
 107 }
 108
 109 static void pseries_mach_cpu_die(void)
 110 {
 111         unsigned int cpu = smp_processor_id();
 112         unsigned int hwcpu = hard_smp_processor_id();
 113         u8 cede_latency_hint = 0;
 114
 115         local_irq_disable();
 116         idle_task_exit();
 117         xics_teardown_cpu();
 118
 119         if (get_preferred_offline_state(cpu) == CPU_STATE_INACTIVE) {
 120                 set_cpu_current_state(cpu, CPU_STATE_INACTIVE);
 121                 if (ppc_md.suspend_disable_cpu)
 122                         ppc_md.suspend_disable_cpu();
 123
 124                 cede_latency_hint = 2;
 125
 126                 get_lppaca()->idle = 1;
 127                 if (!lppaca_shared_proc(get_lppaca()))
 128                         get_lppaca()->donate_dedicated_cpu = 1;
 129
 130                 while (get_preferred_offline_state(cpu) == CPU_STATE_INACTIVE) {
 131                         while (!prep_irq_for_idle()) {
 132                                 local_irq_enable();
 133                                 local_irq_disable();
 134                         }
 135
 136                         extended_cede_processor(cede_latency_hint);
 137                 }
 138
 139                 local_irq_disable();
 140
 141                 if (!lppaca_shared_proc(get_lppaca()))
 142                         get_lppaca()->donate_dedicated_cpu = 0;
 143                 get_lppaca()->idle = 0;
 144
 145                 if (get_preferred_offline_state(cpu) == CPU_STATE_ONLINE) {
 146                         unregister_slb_shadow(hwcpu);
 147
 148                         hard_irq_disable();
 149                         /*
 150                          * Call to start_secondary_resume() will not return.
 151                          * Kernel stack will be reset and start_secondary()
 152                          * will be called to continue the online operation.
 153                          */
 154                         start_secondary_resume();
 155                 }
 156         }
 157
 158         /* Requested state is CPU_STATE_OFFLINE at this point */
 159         WARN_ON(get_preferred_offline_state(cpu) != CPU_STATE_OFFLINE);
 160
 161         set_cpu_current_state(cpu, CPU_STATE_OFFLINE);
 162         unregister_slb_shadow(hwcpu);
 163         rtas_stop_self();
 164
 165         /* Should never get here... */
 166         BUG();
 167         for(;;);
 168 }
 169
 170 static int pseries_cpu_disable(void)
 171 {
 172         int cpu = smp_processor_id();
 173
 174         set_cpu_online(cpu, false);
 175         vdso_data->processorCount--;
 176
 177         /*fix boot_cpuid here*/
 178         if (cpu == boot_cpuid)
 179                 boot_cpuid = cpumask_any(cpu_online_mask);
 180
 181         /* FIXME: abstract this to not be platform specific later on */
 182         xics_migrate_irqs_away();
 183         return 0;
 184 }
 185
 186 /*
 187  * pseries_cpu_die: Wait for the cpu to die.
 188  * @cpu: logical processor id of the CPU whose death we're awaiting.
 189  *
 190  * This function is called from the context of the thread which is performing
 191  * the cpu-offline. Here we wait for long enough to allow the cpu in question
 192  * to self-destroy so that the cpu-offline thread can send the CPU_DEAD
 193  * notifications.
 194  *
 195  * OTOH, pseries_mach_cpu_die() is called by the @cpu when it wants to
 196  * self-destruct.
 197  */
 198 static void pseries_cpu_die(unsigned int cpu)
 199 {
 200         int tries;
 201         int cpu_status = 1;
 202         unsigned int pcpu = get_hard_smp_processor_id(cpu);
 203
 204         if (get_preferred_offline_state(cpu) == CPU_STATE_INACTIVE) {
 205                 cpu_status = 1;
 206                 for (tries = 0; tries < 5000; tries++) {
 207                         if (get_cpu_current_state(cpu) == CPU_STATE_INACTIVE) {
 208                                 cpu_status = 0;
 209                                 break;
 210                         }
 211                         msleep(1);
 212                 }
 213         } else if (get_preferred_offline_state(cpu) == CPU_STATE_OFFLINE) {
 214
 215                 for (tries = 0; tries < 25; tries++) {
 216                         cpu_status = smp_query_cpu_stopped(pcpu);
 217                         if (cpu_status == QCSS_STOPPED ||
 218                             cpu_status == QCSS_HARDWARE_ERROR)
 219                                 break;
 220                         cpu_relax();
 221                 }
 222         }
 223
 224         if (cpu_status != 0) {
 225                 printk("Querying DEAD? cpu %i (%i) shows %i\n",
 226                        cpu, pcpu, cpu_status);
 227         }
 228
 229         /* Isolation and deallocation are definitely done by
 230          * drslot_chrp_cpu.  If they were not they would be
 231          * done here.  Change isolate state to Isolate and
 232          * change allocation-state to Unusable.
 233          */
 234         paca[cpu].cpu_start = 0;
 235 }
 236
 237 /*
 238  * Update cpu_present_mask and paca(s) for a new cpu node.  The wrinkle
 239  * here is that a cpu device node may represent up to two logical cpus
 240  * in the SMT case.  We must honor the assumption in other code that
 241  * the logical ids for sibling SMT threads x and y are adjacent, such
 242  * that x^1 == y and y^1 == x.
 243  */
 244 static int pseries_add_processor(struct device_node *np)
 245 {
 246         unsigned int cpu;
 247         cpumask_var_t candidate_mask, tmp;
 248         int err = -ENOSPC, len, nthreads, i;
 249         const u32 *intserv;
 250
 251         intserv = of_get_property(np, "ibm,ppc-interrupt-server#s", &len);
 252         if (!intserv)
 253                 return 0;
 254
 255         zalloc_cpumask_var(&candidate_mask, GFP_KERNEL);
 256         zalloc_cpumask_var(&tmp, GFP_KERNEL);
 257
 258         nthreads = len / sizeof(u32);
 259         for (i = 0; i < nthreads; i++)
 260                 cpumask_set_cpu(i, tmp);
 261
 262         cpu_maps_update_begin();
 263
 264         BUG_ON(!cpumask_subset(cpu_present_mask, cpu_possible_mask));
 265
 266         /* Get a bitmap of unoccupied slots. */
 267         cpumask_xor(candidate_mask, cpu_possible_mask, cpu_present_mask);
 268         if (cpumask_empty(candidate_mask)) {
 269                 /* If we get here, it most likely means that NR_CPUS is
 270                  * less than the partition's max processors setting.
 271                  */
 272                 printk(KERN_ERR "Cannot add cpu %s; this system configuration"
 273                        " supports %d logical cpus.\n", np->full_name,
 274                        cpumask_weight(cpu_possible_mask));
 275                 goto out_unlock;
 276         }
 277
 278         while (!cpumask_empty(tmp))
 279                 if (cpumask_subset(tmp, candidate_mask))
 280                         /* Found a range where we can insert the new cpu(s) */
 281                         break;
 282                 else
 283                         cpumask_shift_left(tmp, tmp, nthreads);
 284
 285         if (cpumask_empty(tmp)) {
 286                 printk(KERN_ERR "Unable to find space in cpu_present_mask for"
 287                        " processor %s with %d thread(s)\n", np->name,
 288                        nthreads);
 289                 goto out_unlock;
 290         }
 291
 292         for_each_cpu(cpu, tmp) {
 293                 BUG_ON(cpu_present(cpu));
 294                 set_cpu_present(cpu, true);
 295                 set_hard_smp_processor_id(cpu, *intserv++);
 296         }
 297         err = 0;
 298 out_unlock:
 299         cpu_maps_update_done();
 300         free_cpumask_var(candidate_mask);
 301         free_cpumask_var(tmp);
 302         return err;
 303 }
 304
 305 /*
 306  * Update the present map for a cpu node which is going away, and set
 307  * the hard id in the paca(s) to -1 to be consistent with boot time
 308  * convention for non-present cpus.
 309  */
 310 static void pseries_remove_processor(struct device_node *np)
 311 {
 312         unsigned int cpu;
 313         int len, nthreads, i;
 314         const u32 *intserv;
 315
 316         intserv = of_get_property(np, "ibm,ppc-interrupt-server#s", &len);
 317         if (!intserv)
 318                 return;
 319
 320         nthreads = len / sizeof(u32);
 321
 322         cpu_maps_update_begin();
 323         for (i = 0; i < nthreads; i++) {
 324                 for_each_present_cpu(cpu) {
 325                         if (get_hard_smp_processor_id(cpu) != intserv[i])
 326                                 continue;
 327                         BUG_ON(cpu_online(cpu));
 328                         set_cpu_present(cpu, false);
 329                         set_hard_smp_processor_id(cpu, -1);
 330                         break;
 331                 }
 332                 if (cpu >= nr_cpu_ids)
 333                         printk(KERN_WARNING "Could not find cpu to remove "
 334                                "with physical id 0x%x\n", intserv[i]);
 335         }
 336         cpu_maps_update_done();
 337 }
 338
 339 static int pseries_smp_notifier(struct notifier_block *nb,
 340                                 unsigned long action, void *node)
 341 {
 342         int err = 0;
 343
 344         switch (action) {
 345         case OF_RECONFIG_ATTACH_NODE:
 346                 err = pseries_add_processor(node);
 347                 break;
 348         case OF_RECONFIG_DETACH_NODE:
 349                 pseries_remove_processor(node);
 350                 break;
 351         }
 352         return notifier_from_errno(err);
 353 }
 354
 355 static struct notifier_block pseries_smp_nb = {
 356         .notifier_call = pseries_smp_notifier,
 357 };
 358
 359 #define MAX_CEDE_LATENCY_LEVELS         4
 360 #define CEDE_LATENCY_PARAM_LENGTH       10
 361 #define CEDE_LATENCY_PARAM_MAX_LENGTH   \
 362         (MAX_CEDE_LATENCY_LEVELS * CEDE_LATENCY_PARAM_LENGTH * sizeof(char))
 363 #define CEDE_LATENCY_TOKEN              45
 364
 365 static char cede_parameters[CEDE_LATENCY_PARAM_MAX_LENGTH];
 366
 367 static int parse_cede_parameters(void)
 368 {
 369         memset(cede_parameters, 0, CEDE_LATENCY_PARAM_MAX_LENGTH);
 370         return rtas_call(rtas_token("ibm,get-system-parameter"), 3, 1,
 371                          NULL,
 372                          CEDE_LATENCY_TOKEN,
 373                          __pa(cede_parameters),
 374                          CEDE_LATENCY_PARAM_MAX_LENGTH);
 375 }
 376
 377 static int __init pseries_cpu_hotplug_init(void)
 378 {
 379         struct device_node *np;
 380         const char *typep;
 381         int cpu;
 382         int qcss_tok;
 383
 384         for_each_node_by_name(np, "interrupt-controller") {
 385                 typep = of_get_property(np, "compatible", NULL);
 386                 if (strstr(typep, "open-pic")) {
 387                         of_node_put(np);
 388
 389                         printk(KERN_INFO "CPU Hotplug not supported on "
 390                                 "systems using MPIC\n");
 391                         return 0;
 392                 }
 393         }
 394
 395         rtas_stop_self_args.token = rtas_token("stop-self");
 396         qcss_tok = rtas_token("query-cpu-stopped-state");
 397
 398         if (rtas_stop_self_args.token == RTAS_UNKNOWN_SERVICE ||
 399                         qcss_tok == RTAS_UNKNOWN_SERVICE) {
 400                 printk(KERN_INFO "CPU Hotplug not supported by firmware "
 401                                 "- disabling.\n");
 402                 return 0;
 403         }
 404
 405         ppc_md.cpu_die = pseries_mach_cpu_die;
 406         smp_ops->cpu_disable = pseries_cpu_disable;
 407         smp_ops->cpu_die = pseries_cpu_die;
 408
 409         /* Processors can be added/removed only on LPAR */
 410         if (firmware_has_feature(FW_FEATURE_LPAR)) {
 411                 of_reconfig_notifier_register(&pseries_smp_nb);
 412                 cpu_maps_update_begin();
 413                 if (cede_offline_enabled && parse_cede_parameters() == 0) {
 414                         default_offline_state = CPU_STATE_INACTIVE;
 415                         for_each_online_cpu(cpu)
 416                                 set_default_offline_state(cpu);
 417                 }
 418                 cpu_maps_update_done();
 419         }
 420
 421         return 0;
 422 }
 423 arch_initcall(pseries_cpu_hotplug_init);