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 int rtas_stop_self_token = RTAS_UNKNOWN_SERVICE;
  39
  40 static DEFINE_PER_CPU(enum cpu_state_vals, preferred_offline_state) =
  41                                                         CPU_STATE_OFFLINE;
  42 static DEFINE_PER_CPU(enum cpu_state_vals, current_state) = CPU_STATE_OFFLINE;
  43
  44 static enum cpu_state_vals default_offline_state = CPU_STATE_OFFLINE;
  45
  46 static int cede_offline_enabled __read_mostly = 1;
  47
  48 /*
  49  * Enable/disable cede_offline when available.
  50  */
  51 static int __init setup_cede_offline(char *str)
  52 {
  53         if (!strcmp(str, "off"))
  54                 cede_offline_enabled = 0;
  55         else if (!strcmp(str, "on"))
  56                 cede_offline_enabled = 1;
  57         else
  58                 return 0;
  59         return 1;
  60 }
  61
  62 __setup("cede_offline=", setup_cede_offline);
  63
  64 enum cpu_state_vals get_cpu_current_state(int cpu)
  65 {
  66         return per_cpu(current_state, cpu);
  67 }
  68
  69 void set_cpu_current_state(int cpu, enum cpu_state_vals state)
  70 {
  71         per_cpu(current_state, cpu) = state;
  72 }
  73
  74 enum cpu_state_vals get_preferred_offline_state(int cpu)
  75 {
  76         return per_cpu(preferred_offline_state, cpu);
  77 }
  78
  79 void set_preferred_offline_state(int cpu, enum cpu_state_vals state)
  80 {
  81         per_cpu(preferred_offline_state, cpu) = state;
  82 }
  83
  84 void set_default_offline_state(int cpu)
  85 {
  86         per_cpu(preferred_offline_state, cpu) = default_offline_state;
  87 }
  88
  89 static void rtas_stop_self(void)
  90 {
  91         static struct rtas_args args = {
  92                 .nargs = 0,
  93                 .nret = cpu_to_be32(1),
  94                 .rets = &args.args[0],
  95         };
  96
  97         args.token = cpu_to_be32(rtas_stop_self_token);
  98
  99         local_irq_disable();
 100
 101         BUG_ON(rtas_stop_self_token == RTAS_UNKNOWN_SERVICE);
 102
 103         printk("cpu %u (hwid %u) Ready to die...\n",
 104                smp_processor_id(), hard_smp_processor_id());
 105         enter_rtas(__pa(&args));
 106
 107         panic("Alas, I survived.\n");
 108 }
 109
 110 static void pseries_mach_cpu_die(void)
 111 {
 112         unsigned int cpu = smp_processor_id();
 113         unsigned int hwcpu = hard_smp_processor_id();
 114         u8 cede_latency_hint = 0;
 115
 116         local_irq_disable();
 117         idle_task_exit();
 118         xics_teardown_cpu();
 119
 120         if (get_preferred_offline_state(cpu) == CPU_STATE_INACTIVE) {
 121                 set_cpu_current_state(cpu, CPU_STATE_INACTIVE);
 122                 if (ppc_md.suspend_disable_cpu)
 123                         ppc_md.suspend_disable_cpu();
 124
 125                 cede_latency_hint = 2;
 126
 127                 get_lppaca()->idle = 1;
 128                 if (!lppaca_shared_proc(get_lppaca()))
 129                         get_lppaca()->donate_dedicated_cpu = 1;
 130
 131                 while (get_preferred_offline_state(cpu) == CPU_STATE_INACTIVE) {
 132                         while (!prep_irq_for_idle()) {
 133                                 local_irq_enable();
 134                                 local_irq_disable();
 135                         }
 136
 137                         extended_cede_processor(cede_latency_hint);
 138                 }
 139
 140                 local_irq_disable();
 141
 142                 if (!lppaca_shared_proc(get_lppaca()))
 143                         get_lppaca()->donate_dedicated_cpu = 0;
 144                 get_lppaca()->idle = 0;
 145
 146                 if (get_preferred_offline_state(cpu) == CPU_STATE_ONLINE) {
 147                         unregister_slb_shadow(hwcpu);
 148
 149                         hard_irq_disable();
 150                         /*
 151                          * Call to start_secondary_resume() will not return.
 152                          * Kernel stack will be reset and start_secondary()
 153                          * will be called to continue the online operation.
 154                          */
 155                         start_secondary_resume();
 156                 }
 157         }
 158
 159         /* Requested state is CPU_STATE_OFFLINE at this point */
 160         WARN_ON(get_preferred_offline_state(cpu) != CPU_STATE_OFFLINE);
 161
 162         set_cpu_current_state(cpu, CPU_STATE_OFFLINE);
 163         unregister_slb_shadow(hwcpu);
 164         rtas_stop_self();
 165
 166         /* Should never get here... */
 167         BUG();
 168         for(;;);
 169 }
 170
 171 static int pseries_cpu_disable(void)
 172 {
 173         int cpu = smp_processor_id();
 174
 175         set_cpu_online(cpu, false);
 176         vdso_data->processorCount--;
 177
 178         /*fix boot_cpuid here*/
 179         if (cpu == boot_cpuid)
 180                 boot_cpuid = cpumask_any(cpu_online_mask);
 181
 182         /* FIXME: abstract this to not be platform specific later on */
 183         xics_migrate_irqs_away();
 184         return 0;
 185 }
 186
 187 /*
 188  * pseries_cpu_die: Wait for the cpu to die.
 189  * @cpu: logical processor id of the CPU whose death we're awaiting.
 190  *
 191  * This function is called from the context of the thread which is performing
 192  * the cpu-offline. Here we wait for long enough to allow the cpu in question
 193  * to self-destroy so that the cpu-offline thread can send the CPU_DEAD
 194  * notifications.
 195  *
 196  * OTOH, pseries_mach_cpu_die() is called by the @cpu when it wants to
 197  * self-destruct.
 198  */
 199 static void pseries_cpu_die(unsigned int cpu)
 200 {
 201         int tries;
 202         int cpu_status = 1;
 203         unsigned int pcpu = get_hard_smp_processor_id(cpu);
 204
 205         if (get_preferred_offline_state(cpu) == CPU_STATE_INACTIVE) {
 206                 cpu_status = 1;
 207                 for (tries = 0; tries < 5000; tries++) {
 208                         if (get_cpu_current_state(cpu) == CPU_STATE_INACTIVE) {
 209                                 cpu_status = 0;
 210                                 break;
 211                         }
 212                         msleep(1);
 213                 }
 214         } else if (get_preferred_offline_state(cpu) == CPU_STATE_OFFLINE) {
 215
 216                 for (tries = 0; tries < 25; tries++) {
 217                         cpu_status = smp_query_cpu_stopped(pcpu);
 218                         if (cpu_status == QCSS_STOPPED ||
 219                             cpu_status == QCSS_HARDWARE_ERROR)
 220                                 break;
 221                         cpu_relax();
 222                 }
 223         }
 224
 225         if (cpu_status != 0) {
 226                 printk("Querying DEAD? cpu %i (%i) shows %i\n",
 227                        cpu, pcpu, cpu_status);
 228         }
 229
 230         /* Isolation and deallocation are definitely done by
 231          * drslot_chrp_cpu.  If they were not they would be
 232          * done here.  Change isolate state to Isolate and
 233          * change allocation-state to Unusable.
 234          */
 235         paca[cpu].cpu_start = 0;
 236 }
 237
 238 /*
 239  * Update cpu_present_mask and paca(s) for a new cpu node.  The wrinkle
 240  * here is that a cpu device node may represent up to two logical cpus
 241  * in the SMT case.  We must honor the assumption in other code that
 242  * the logical ids for sibling SMT threads x and y are adjacent, such
 243  * that x^1 == y and y^1 == x.
 244  */
 245 static int pseries_add_processor(struct device_node *np)
 246 {
 247         unsigned int cpu;
 248         cpumask_var_t candidate_mask, tmp;
 249         int err = -ENOSPC, len, nthreads, i;
 250         const __be32 *intserv;
 251
 252         intserv = of_get_property(np, "ibm,ppc-interrupt-server#s", &len);
 253         if (!intserv)
 254                 return 0;
 255
 256         zalloc_cpumask_var(&candidate_mask, GFP_KERNEL);
 257         zalloc_cpumask_var(&tmp, GFP_KERNEL);
 258
 259         nthreads = len / sizeof(u32);
 260         for (i = 0; i < nthreads; i++)
 261                 cpumask_set_cpu(i, tmp);
 262
 263         cpu_maps_update_begin();
 264
 265         BUG_ON(!cpumask_subset(cpu_present_mask, cpu_possible_mask));
 266
 267         /* Get a bitmap of unoccupied slots. */
 268         cpumask_xor(candidate_mask, cpu_possible_mask, cpu_present_mask);
 269         if (cpumask_empty(candidate_mask)) {
 270                 /* If we get here, it most likely means that NR_CPUS is
 271                  * less than the partition's max processors setting.
 272                  */
 273                 printk(KERN_ERR "Cannot add cpu %s; this system configuration"
 274                        " supports %d logical cpus.\n", np->full_name,
 275                        cpumask_weight(cpu_possible_mask));
 276                 goto out_unlock;
 277         }
 278
 279         while (!cpumask_empty(tmp))
 280                 if (cpumask_subset(tmp, candidate_mask))
 281                         /* Found a range where we can insert the new cpu(s) */
 282                         break;
 283                 else
 284                         cpumask_shift_left(tmp, tmp, nthreads);
 285
 286         if (cpumask_empty(tmp)) {
 287                 printk(KERN_ERR "Unable to find space in cpu_present_mask for"
 288                        " processor %s with %d thread(s)\n", np->name,
 289                        nthreads);
 290                 goto out_unlock;
 291         }
 292
 293         for_each_cpu(cpu, tmp) {
 294                 BUG_ON(cpu_present(cpu));
 295                 set_cpu_present(cpu, true);
 296                 set_hard_smp_processor_id(cpu, be32_to_cpu(*intserv++));
 297         }
 298         err = 0;
 299 out_unlock:
 300         cpu_maps_update_done();
 301         free_cpumask_var(candidate_mask);
 302         free_cpumask_var(tmp);
 303         return err;
 304 }
 305
 306 /*
 307  * Update the present map for a cpu node which is going away, and set
 308  * the hard id in the paca(s) to -1 to be consistent with boot time
 309  * convention for non-present cpus.
 310  */
 311 static void pseries_remove_processor(struct device_node *np)
 312 {
 313         unsigned int cpu;
 314         int len, nthreads, i;
 315         const __be32 *intserv;
 316         u32 thread;
 317
 318         intserv = of_get_property(np, "ibm,ppc-interrupt-server#s", &len);
 319         if (!intserv)
 320                 return;
 321
 322         nthreads = len / sizeof(u32);
 323
 324         cpu_maps_update_begin();
 325         for (i = 0; i < nthreads; i++) {
 326                 thread = be32_to_cpu(intserv[i]);
 327                 for_each_present_cpu(cpu) {
 328                         if (get_hard_smp_processor_id(cpu) != thread)
 329                                 continue;
 330                         BUG_ON(cpu_online(cpu));
 331                         set_cpu_present(cpu, false);
 332                         set_hard_smp_processor_id(cpu, -1);
 333                         break;
 334                 }
 335                 if (cpu >= nr_cpu_ids)
 336                         printk(KERN_WARNING "Could not find cpu to remove "
 337                                "with physical id 0x%x\n", thread);
 338         }
 339         cpu_maps_update_done();
 340 }
 341
 342 static int pseries_smp_notifier(struct notifier_block *nb,
 343                                 unsigned long action, void *node)
 344 {
 345         int err = 0;
 346
 347         switch (action) {
 348         case OF_RECONFIG_ATTACH_NODE:
 349                 err = pseries_add_processor(node);
 350                 break;
 351         case OF_RECONFIG_DETACH_NODE:
 352                 pseries_remove_processor(node);
 353                 break;
 354         }
 355         return notifier_from_errno(err);
 356 }
 357
 358 static struct notifier_block pseries_smp_nb = {
 359         .notifier_call = pseries_smp_notifier,
 360 };
 361
 362 #define MAX_CEDE_LATENCY_LEVELS         4
 363 #define CEDE_LATENCY_PARAM_LENGTH       10
 364 #define CEDE_LATENCY_PARAM_MAX_LENGTH   \
 365         (MAX_CEDE_LATENCY_LEVELS * CEDE_LATENCY_PARAM_LENGTH * sizeof(char))
 366 #define CEDE_LATENCY_TOKEN              45
 367
 368 static char cede_parameters[CEDE_LATENCY_PARAM_MAX_LENGTH];
 369
 370 static int parse_cede_parameters(void)
 371 {
 372         memset(cede_parameters, 0, CEDE_LATENCY_PARAM_MAX_LENGTH);
 373         return rtas_call(rtas_token("ibm,get-system-parameter"), 3, 1,
 374                          NULL,
 375                          CEDE_LATENCY_TOKEN,
 376                          __pa(cede_parameters),
 377                          CEDE_LATENCY_PARAM_MAX_LENGTH);
 378 }
 379
 380 static int __init pseries_cpu_hotplug_init(void)
 381 {
 382         struct device_node *np;
 383         const char *typep;
 384         int cpu;
 385         int qcss_tok;
 386
 387         for_each_node_by_name(np, "interrupt-controller") {
 388                 typep = of_get_property(np, "compatible", NULL);
 389                 if (strstr(typep, "open-pic")) {
 390                         of_node_put(np);
 391
 392                         printk(KERN_INFO "CPU Hotplug not supported on "
 393                                 "systems using MPIC\n");
 394                         return 0;
 395                 }
 396         }
 397
 398         rtas_stop_self_token = rtas_token("stop-self");
 399         qcss_tok = rtas_token("query-cpu-stopped-state");
 400
 401         if (rtas_stop_self_token == RTAS_UNKNOWN_SERVICE ||
 402                         qcss_tok == RTAS_UNKNOWN_SERVICE) {
 403                 printk(KERN_INFO "CPU Hotplug not supported by firmware "
 404                                 "- disabling.\n");
 405                 return 0;
 406         }
 407
 408         ppc_md.cpu_die = pseries_mach_cpu_die;
 409         smp_ops->cpu_disable = pseries_cpu_disable;
 410         smp_ops->cpu_die = pseries_cpu_die;
 411
 412         /* Processors can be added/removed only on LPAR */
 413         if (firmware_has_feature(FW_FEATURE_LPAR)) {
 414                 of_reconfig_notifier_register(&pseries_smp_nb);
 415                 cpu_maps_update_begin();
 416                 if (cede_offline_enabled && parse_cede_parameters() == 0) {
 417                         default_offline_state = CPU_STATE_INACTIVE;
 418                         for_each_online_cpu(cpu)
 419                                 set_default_offline_state(cpu);
 420                 }
 421                 cpu_maps_update_done();
 422         }
 423
 424         return 0;
 425 }
 426 machine_arch_initcall(pseries, pseries_cpu_hotplug_init);