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