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 <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 */
  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 (!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
 162 static 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  */
 190 static 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  */
 236 static 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;
 290 out_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  */
 302 static 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
 331 static 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
 347 static 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
 357 static char cede_parameters[CEDE_LATENCY_PARAM_MAX_LENGTH];
 358
 359 static 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
 369 static 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 }
 415 arch_initcall(pseries_cpu_hotplug_init);