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