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