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 #define pr_fmt(fmt)     "pseries-hotplug-cpu: " fmt
  22
  23 #include <linux/kernel.h>
  24 #include <linux/interrupt.h>
  25 #include <linux/delay.h>
  26 #include <linux/sched.h>        /* for idle_task_exit */
  27 #include <linux/sched/hotplug.h>
  28 #include <linux/cpu.h>
  29 #include <linux/of.h>
  30 #include <linux/slab.h>
  31 #include <asm/prom.h>
  32 #include <asm/rtas.h>
  33 #include <asm/firmware.h>
  34 #include <asm/machdep.h>
  35 #include <asm/vdso_datapage.h>
  36 #include <asm/xics.h>
  37 #include <asm/plpar_wrappers.h>
  38
  39 #include "pseries.h"
  40 #include "offline_states.h"
  41
  42 /* This version can't take the spinlock, because it never returns */
  43 static int rtas_stop_self_token = RTAS_UNKNOWN_SERVICE;
  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 bool cede_offline_enabled __read_mostly = true;
  52
  53 /*
  54  * Enable/disable cede_offline when available.
  55  */
  56 static int __init setup_cede_offline(char *str)
  57 {
  58         return (kstrtobool(str, &cede_offline_enabled) == 0);
  59 }
  60
  61 __setup("cede_offline=", setup_cede_offline);
  62
  63 enum cpu_state_vals get_cpu_current_state(int cpu)
  64 {
  65         return per_cpu(current_state, cpu);
  66 }
  67
  68 void set_cpu_current_state(int cpu, enum cpu_state_vals state)
  69 {
  70         per_cpu(current_state, cpu) = state;
  71 }
  72
  73 enum cpu_state_vals get_preferred_offline_state(int cpu)
  74 {
  75         return per_cpu(preferred_offline_state, cpu);
  76 }
  77
  78 void set_preferred_offline_state(int cpu, enum cpu_state_vals state)
  79 {
  80         per_cpu(preferred_offline_state, cpu) = state;
  81 }
  82
  83 void set_default_offline_state(int cpu)
  84 {
  85         per_cpu(preferred_offline_state, cpu) = default_offline_state;
  86 }
  87
  88 static void rtas_stop_self(void)
  89 {
  90         static struct rtas_args args;
  91
  92         local_irq_disable();
  93
  94         BUG_ON(rtas_stop_self_token == RTAS_UNKNOWN_SERVICE);
  95
  96         printk("cpu %u (hwid %u) Ready to die...\n",
  97                smp_processor_id(), hard_smp_processor_id());
  98
  99         rtas_call_unlocked(&args, rtas_stop_self_token, 0, 1, NULL);
 100
 101         panic("Alas, I survived.\n");
 102 }
 103
 104 static void pseries_mach_cpu_die(void)
 105 {
 106         unsigned int cpu = smp_processor_id();
 107         unsigned int hwcpu = hard_smp_processor_id();
 108         u8 cede_latency_hint = 0;
 109
 110         local_irq_disable();
 111         idle_task_exit();
 112         xics_teardown_cpu();
 113
 114         if (get_preferred_offline_state(cpu) == CPU_STATE_INACTIVE) {
 115                 set_cpu_current_state(cpu, CPU_STATE_INACTIVE);
 116                 if (ppc_md.suspend_disable_cpu)
 117                         ppc_md.suspend_disable_cpu();
 118
 119                 cede_latency_hint = 2;
 120
 121                 get_lppaca()->idle = 1;
 122                 if (!lppaca_shared_proc(get_lppaca()))
 123                         get_lppaca()->donate_dedicated_cpu = 1;
 124
 125                 while (get_preferred_offline_state(cpu) == CPU_STATE_INACTIVE) {
 126                         while (!prep_irq_for_idle()) {
 127                                 local_irq_enable();
 128                                 local_irq_disable();
 129                         }
 130
 131                         extended_cede_processor(cede_latency_hint);
 132                 }
 133
 134                 local_irq_disable();
 135
 136                 if (!lppaca_shared_proc(get_lppaca()))
 137                         get_lppaca()->donate_dedicated_cpu = 0;
 138                 get_lppaca()->idle = 0;
 139
 140                 if (get_preferred_offline_state(cpu) == CPU_STATE_ONLINE) {
 141                         unregister_slb_shadow(hwcpu);
 142
 143                         hard_irq_disable();
 144                         /*
 145                          * Call to start_secondary_resume() will not return.
 146                          * Kernel stack will be reset and start_secondary()
 147                          * will be called to continue the online operation.
 148                          */
 149                         start_secondary_resume();
 150                 }
 151         }
 152
 153         /* Requested state is CPU_STATE_OFFLINE at this point */
 154         WARN_ON(get_preferred_offline_state(cpu) != CPU_STATE_OFFLINE);
 155
 156         set_cpu_current_state(cpu, CPU_STATE_OFFLINE);
 157         unregister_slb_shadow(hwcpu);
 158         rtas_stop_self();
 159
 160         /* Should never get here... */
 161         BUG();
 162         for(;;);
 163 }
 164
 165 static int pseries_cpu_disable(void)
 166 {
 167         int cpu = smp_processor_id();
 168
 169         set_cpu_online(cpu, false);
 170         vdso_data->processorCount--;
 171
 172         /*fix boot_cpuid here*/
 173         if (cpu == boot_cpuid)
 174                 boot_cpuid = cpumask_any(cpu_online_mask);
 175
 176         /* FIXME: abstract this to not be platform specific later on */
 177         xics_migrate_irqs_away();
 178         return 0;
 179 }
 180
 181 /*
 182  * pseries_cpu_die: Wait for the cpu to die.
 183  * @cpu: logical processor id of the CPU whose death we're awaiting.
 184  *
 185  * This function is called from the context of the thread which is performing
 186  * the cpu-offline. Here we wait for long enough to allow the cpu in question
 187  * to self-destroy so that the cpu-offline thread can send the CPU_DEAD
 188  * notifications.
 189  *
 190  * OTOH, pseries_mach_cpu_die() is called by the @cpu when it wants to
 191  * self-destruct.
 192  */
 193 static void pseries_cpu_die(unsigned int cpu)
 194 {
 195         int tries;
 196         int cpu_status = 1;
 197         unsigned int pcpu = get_hard_smp_processor_id(cpu);
 198
 199         if (get_preferred_offline_state(cpu) == CPU_STATE_INACTIVE) {
 200                 cpu_status = 1;
 201                 for (tries = 0; tries < 5000; tries++) {
 202                         if (get_cpu_current_state(cpu) == CPU_STATE_INACTIVE) {
 203                                 cpu_status = 0;
 204                                 break;
 205                         }
 206                         msleep(1);
 207                 }
 208         } else if (get_preferred_offline_state(cpu) == CPU_STATE_OFFLINE) {
 209
 210                 for (tries = 0; tries < 25; tries++) {
 211                         cpu_status = smp_query_cpu_stopped(pcpu);
 212                         if (cpu_status == QCSS_STOPPED ||
 213                             cpu_status == QCSS_HARDWARE_ERROR)
 214                                 break;
 215                         cpu_relax();
 216                 }
 217         }
 218
 219         if (cpu_status != 0) {
 220                 printk("Querying DEAD? cpu %i (%i) shows %i\n",
 221                        cpu, pcpu, cpu_status);
 222         }
 223
 224         /* Isolation and deallocation are definitely done by
 225          * drslot_chrp_cpu.  If they were not they would be
 226          * done here.  Change isolate state to Isolate and
 227          * change allocation-state to Unusable.
 228          */
 229         paca[cpu].cpu_start = 0;
 230 }
 231
 232 /*
 233  * Update cpu_present_mask and paca(s) for a new cpu node.  The wrinkle
 234  * here is that a cpu device node may represent up to two logical cpus
 235  * in the SMT case.  We must honor the assumption in other code that
 236  * the logical ids for sibling SMT threads x and y are adjacent, such
 237  * that x^1 == y and y^1 == x.
 238  */
 239 static int pseries_add_processor(struct device_node *np)
 240 {
 241         unsigned int cpu;
 242         cpumask_var_t candidate_mask, tmp;
 243         int err = -ENOSPC, len, nthreads, i;
 244         const __be32 *intserv;
 245
 246         intserv = of_get_property(np, "ibm,ppc-interrupt-server#s", &len);
 247         if (!intserv)
 248                 return 0;
 249
 250         zalloc_cpumask_var(&candidate_mask, GFP_KERNEL);
 251         zalloc_cpumask_var(&tmp, GFP_KERNEL);
 252
 253         nthreads = len / sizeof(u32);
 254         for (i = 0; i < nthreads; i++)
 255                 cpumask_set_cpu(i, tmp);
 256
 257         cpu_maps_update_begin();
 258
 259         BUG_ON(!cpumask_subset(cpu_present_mask, cpu_possible_mask));
 260
 261         /* Get a bitmap of unoccupied slots. */
 262         cpumask_xor(candidate_mask, cpu_possible_mask, cpu_present_mask);
 263         if (cpumask_empty(candidate_mask)) {
 264                 /* If we get here, it most likely means that NR_CPUS is
 265                  * less than the partition's max processors setting.
 266                  */
 267                 printk(KERN_ERR "Cannot add cpu %s; this system configuration"
 268                        " supports %d logical cpus.\n", np->full_name,
 269                        num_possible_cpus());
 270                 goto out_unlock;
 271         }
 272
 273         while (!cpumask_empty(tmp))
 274                 if (cpumask_subset(tmp, candidate_mask))
 275                         /* Found a range where we can insert the new cpu(s) */
 276                         break;
 277                 else
 278                         cpumask_shift_left(tmp, tmp, nthreads);
 279
 280         if (cpumask_empty(tmp)) {
 281                 printk(KERN_ERR "Unable to find space in cpu_present_mask for"
 282                        " processor %s with %d thread(s)\n", np->name,
 283                        nthreads);
 284                 goto out_unlock;
 285         }
 286
 287         for_each_cpu(cpu, tmp) {
 288                 BUG_ON(cpu_present(cpu));
 289                 set_cpu_present(cpu, true);
 290                 set_hard_smp_processor_id(cpu, be32_to_cpu(*intserv++));
 291         }
 292         err = 0;
 293 out_unlock:
 294         cpu_maps_update_done();
 295         free_cpumask_var(candidate_mask);
 296         free_cpumask_var(tmp);
 297         return err;
 298 }
 299
 300 /*
 301  * Update the present map for a cpu node which is going away, and set
 302  * the hard id in the paca(s) to -1 to be consistent with boot time
 303  * convention for non-present cpus.
 304  */
 305 static void pseries_remove_processor(struct device_node *np)
 306 {
 307         unsigned int cpu;
 308         int len, nthreads, i;
 309         const __be32 *intserv;
 310         u32 thread;
 311
 312         intserv = of_get_property(np, "ibm,ppc-interrupt-server#s", &len);
 313         if (!intserv)
 314                 return;
 315
 316         nthreads = len / sizeof(u32);
 317
 318         cpu_maps_update_begin();
 319         for (i = 0; i < nthreads; i++) {
 320                 thread = be32_to_cpu(intserv[i]);
 321                 for_each_present_cpu(cpu) {
 322                         if (get_hard_smp_processor_id(cpu) != thread)
 323                                 continue;
 324                         BUG_ON(cpu_online(cpu));
 325                         set_cpu_present(cpu, false);
 326                         set_hard_smp_processor_id(cpu, -1);
 327                         break;
 328                 }
 329                 if (cpu >= nr_cpu_ids)
 330                         printk(KERN_WARNING "Could not find cpu to remove "
 331                                "with physical id 0x%x\n", thread);
 332         }
 333         cpu_maps_update_done();
 334 }
 335
 336 static int dlpar_online_cpu(struct device_node *dn)
 337 {
 338         int rc = 0;
 339         unsigned int cpu;
 340         int len, nthreads, i;
 341         const __be32 *intserv;
 342         u32 thread;
 343
 344         intserv = of_get_property(dn, "ibm,ppc-interrupt-server#s", &len);
 345         if (!intserv)
 346                 return -EINVAL;
 347
 348         nthreads = len / sizeof(u32);
 349
 350         cpu_maps_update_begin();
 351         for (i = 0; i < nthreads; i++) {
 352                 thread = be32_to_cpu(intserv[i]);
 353                 for_each_present_cpu(cpu) {
 354                         if (get_hard_smp_processor_id(cpu) != thread)
 355                                 continue;
 356                         BUG_ON(get_cpu_current_state(cpu)
 357                                         != CPU_STATE_OFFLINE);
 358                         cpu_maps_update_done();
 359                         rc = device_online(get_cpu_device(cpu));
 360                         if (rc)
 361                                 goto out;
 362                         cpu_maps_update_begin();
 363
 364                         break;
 365                 }
 366                 if (cpu == num_possible_cpus())
 367                         printk(KERN_WARNING "Could not find cpu to online "
 368                                "with physical id 0x%x\n", thread);
 369         }
 370         cpu_maps_update_done();
 371
 372 out:
 373         return rc;
 374
 375 }
 376
 377 static bool dlpar_cpu_exists(struct device_node *parent, u32 drc_index)
 378 {
 379         struct device_node *child = NULL;
 380         u32 my_drc_index;
 381         bool found;
 382         int rc;
 383
 384         /* Assume cpu doesn't exist */
 385         found = false;
 386
 387         for_each_child_of_node(parent, child) {
 388                 rc = of_property_read_u32(child, "ibm,my-drc-index",
 389                                           &my_drc_index);
 390                 if (rc)
 391                         continue;
 392
 393                 if (my_drc_index == drc_index) {
 394                         of_node_put(child);
 395                         found = true;
 396                         break;
 397                 }
 398         }
 399
 400         return found;
 401 }
 402
 403 static bool valid_cpu_drc_index(struct device_node *parent, u32 drc_index)
 404 {
 405         bool found = false;
 406         int rc, index;
 407
 408         index = 0;
 409         while (!found) {
 410                 u32 drc;
 411
 412                 rc = of_property_read_u32_index(parent, "ibm,drc-indexes",
 413                                                 index++, &drc);
 414                 if (rc)
 415                         break;
 416
 417                 if (drc == drc_index)
 418                         found = true;
 419         }
 420
 421         return found;
 422 }
 423
 424 static ssize_t dlpar_cpu_add(u32 drc_index)
 425 {
 426         struct device_node *dn, *parent;
 427         int rc, saved_rc;
 428
 429         pr_debug("Attempting to add CPU, drc index: %x\n", drc_index);
 430
 431         parent = of_find_node_by_path("/cpus");
 432         if (!parent) {
 433                 pr_warn("Failed to find CPU root node \"/cpus\"\n");
 434                 return -ENODEV;
 435         }
 436
 437         if (dlpar_cpu_exists(parent, drc_index)) {
 438                 of_node_put(parent);
 439                 pr_warn("CPU with drc index %x already exists\n", drc_index);
 440                 return -EINVAL;
 441         }
 442
 443         if (!valid_cpu_drc_index(parent, drc_index)) {
 444                 of_node_put(parent);
 445                 pr_warn("Cannot find CPU (drc index %x) to add.\n", drc_index);
 446                 return -EINVAL;
 447         }
 448
 449         rc = dlpar_acquire_drc(drc_index);
 450         if (rc) {
 451                 pr_warn("Failed to acquire DRC, rc: %d, drc index: %x\n",
 452                         rc, drc_index);
 453                 of_node_put(parent);
 454                 return -EINVAL;
 455         }
 456
 457         dn = dlpar_configure_connector(cpu_to_be32(drc_index), parent);
 458         of_node_put(parent);
 459         if (!dn) {
 460                 pr_warn("Failed call to configure-connector, drc index: %x\n",
 461                         drc_index);
 462                 dlpar_release_drc(drc_index);
 463                 return -EINVAL;
 464         }
 465
 466         rc = dlpar_attach_node(dn);
 467         if (rc) {
 468                 saved_rc = rc;
 469                 pr_warn("Failed to attach node %s, rc: %d, drc index: %x\n",
 470                         dn->name, rc, drc_index);
 471
 472                 rc = dlpar_release_drc(drc_index);
 473                 if (!rc)
 474                         dlpar_free_cc_nodes(dn);
 475
 476                 return saved_rc;
 477         }
 478
 479         rc = dlpar_online_cpu(dn);
 480         if (rc) {
 481                 saved_rc = rc;
 482                 pr_warn("Failed to online cpu %s, rc: %d, drc index: %x\n",
 483                         dn->name, rc, drc_index);
 484
 485                 rc = dlpar_detach_node(dn);
 486                 if (!rc)
 487                         dlpar_release_drc(drc_index);
 488
 489                 return saved_rc;
 490         }
 491
 492         pr_debug("Successfully added CPU %s, drc index: %x\n", dn->name,
 493                  drc_index);
 494         return rc;
 495 }
 496
 497 static int dlpar_offline_cpu(struct device_node *dn)
 498 {
 499         int rc = 0;
 500         unsigned int cpu;
 501         int len, nthreads, i;
 502         const __be32 *intserv;
 503         u32 thread;
 504
 505         intserv = of_get_property(dn, "ibm,ppc-interrupt-server#s", &len);
 506         if (!intserv)
 507                 return -EINVAL;
 508
 509         nthreads = len / sizeof(u32);
 510
 511         cpu_maps_update_begin();
 512         for (i = 0; i < nthreads; i++) {
 513                 thread = be32_to_cpu(intserv[i]);
 514                 for_each_present_cpu(cpu) {
 515                         if (get_hard_smp_processor_id(cpu) != thread)
 516                                 continue;
 517
 518                         if (get_cpu_current_state(cpu) == CPU_STATE_OFFLINE)
 519                                 break;
 520
 521                         if (get_cpu_current_state(cpu) == CPU_STATE_ONLINE) {
 522                                 set_preferred_offline_state(cpu,
 523                                                             CPU_STATE_OFFLINE);
 524                                 cpu_maps_update_done();
 525                                 rc = device_offline(get_cpu_device(cpu));
 526                                 if (rc)
 527                                         goto out;
 528                                 cpu_maps_update_begin();
 529                                 break;
 530
 531                         }
 532
 533                         /*
 534                          * The cpu is in CPU_STATE_INACTIVE.
 535                          * Upgrade it's state to CPU_STATE_OFFLINE.
 536                          */
 537                         set_preferred_offline_state(cpu, CPU_STATE_OFFLINE);
 538                         BUG_ON(plpar_hcall_norets(H_PROD, thread)
 539                                                                 != H_SUCCESS);
 540                         __cpu_die(cpu);
 541                         break;
 542                 }
 543                 if (cpu == num_possible_cpus())
 544                         printk(KERN_WARNING "Could not find cpu to offline with physical id 0x%x\n", thread);
 545         }
 546         cpu_maps_update_done();
 547
 548 out:
 549         return rc;
 550
 551 }
 552
 553 static ssize_t dlpar_cpu_remove(struct device_node *dn, u32 drc_index)
 554 {
 555         int rc;
 556
 557         pr_debug("Attempting to remove CPU %s, drc index: %x\n",
 558                  dn->name, drc_index);
 559
 560         rc = dlpar_offline_cpu(dn);
 561         if (rc) {
 562                 pr_warn("Failed to offline CPU %s, rc: %d\n", dn->name, rc);
 563                 return -EINVAL;
 564         }
 565
 566         rc = dlpar_release_drc(drc_index);
 567         if (rc) {
 568                 pr_warn("Failed to release drc (%x) for CPU %s, rc: %d\n",
 569                         drc_index, dn->name, rc);
 570                 dlpar_online_cpu(dn);
 571                 return rc;
 572         }
 573
 574         rc = dlpar_detach_node(dn);
 575         if (rc) {
 576                 int saved_rc = rc;
 577
 578                 pr_warn("Failed to detach CPU %s, rc: %d", dn->name, rc);
 579
 580                 rc = dlpar_acquire_drc(drc_index);
 581                 if (!rc)
 582                         dlpar_online_cpu(dn);
 583
 584                 return saved_rc;
 585         }
 586
 587         pr_debug("Successfully removed CPU, drc index: %x\n", drc_index);
 588         return 0;
 589 }
 590
 591 static struct device_node *cpu_drc_index_to_dn(u32 drc_index)
 592 {
 593         struct device_node *dn;
 594         u32 my_index;
 595         int rc;
 596
 597         for_each_node_by_type(dn, "cpu") {
 598                 rc = of_property_read_u32(dn, "ibm,my-drc-index", &my_index);
 599                 if (rc)
 600                         continue;
 601
 602                 if (my_index == drc_index)
 603                         break;
 604         }
 605
 606         return dn;
 607 }
 608
 609 static int dlpar_cpu_remove_by_index(u32 drc_index)
 610 {
 611         struct device_node *dn;
 612         int rc;
 613
 614         dn = cpu_drc_index_to_dn(drc_index);
 615         if (!dn) {
 616                 pr_warn("Cannot find CPU (drc index %x) to remove\n",
 617                         drc_index);
 618                 return -ENODEV;
 619         }
 620
 621         rc = dlpar_cpu_remove(dn, drc_index);
 622         of_node_put(dn);
 623         return rc;
 624 }
 625
 626 static int find_dlpar_cpus_to_remove(u32 *cpu_drcs, int cpus_to_remove)
 627 {
 628         struct device_node *dn;
 629         int cpus_found = 0;
 630         int rc;
 631
 632         /* We want to find cpus_to_remove + 1 CPUs to ensure we do not
 633          * remove the last CPU.
 634          */
 635         for_each_node_by_type(dn, "cpu") {
 636                 cpus_found++;
 637
 638                 if (cpus_found > cpus_to_remove) {
 639                         of_node_put(dn);
 640                         break;
 641                 }
 642
 643                 /* Note that cpus_found is always 1 ahead of the index
 644                  * into the cpu_drcs array, so we use cpus_found - 1
 645                  */
 646                 rc = of_property_read_u32(dn, "ibm,my-drc-index",
 647                                           &cpu_drcs[cpus_found - 1]);
 648                 if (rc) {
 649                         pr_warn("Error occurred getting drc-index for %s\n",
 650                                 dn->name);
 651                         of_node_put(dn);
 652                         return -1;
 653                 }
 654         }
 655
 656         if (cpus_found < cpus_to_remove) {
 657                 pr_warn("Failed to find enough CPUs (%d of %d) to remove\n",
 658                         cpus_found, cpus_to_remove);
 659         } else if (cpus_found == cpus_to_remove) {
 660                 pr_warn("Cannot remove all CPUs\n");
 661         }
 662
 663         return cpus_found;
 664 }
 665
 666 static int dlpar_cpu_remove_by_count(u32 cpus_to_remove)
 667 {
 668         u32 *cpu_drcs;
 669         int cpus_found;
 670         int cpus_removed = 0;
 671         int i, rc;
 672
 673         pr_debug("Attempting to hot-remove %d CPUs\n", cpus_to_remove);
 674
 675         cpu_drcs = kcalloc(cpus_to_remove, sizeof(*cpu_drcs), GFP_KERNEL);
 676         if (!cpu_drcs)
 677                 return -EINVAL;
 678
 679         cpus_found = find_dlpar_cpus_to_remove(cpu_drcs, cpus_to_remove);
 680         if (cpus_found <= cpus_to_remove) {
 681                 kfree(cpu_drcs);
 682                 return -EINVAL;
 683         }
 684
 685         for (i = 0; i < cpus_to_remove; i++) {
 686                 rc = dlpar_cpu_remove_by_index(cpu_drcs[i]);
 687                 if (rc)
 688                         break;
 689
 690                 cpus_removed++;
 691         }
 692
 693         if (cpus_removed != cpus_to_remove) {
 694                 pr_warn("CPU hot-remove failed, adding back removed CPUs\n");
 695
 696                 for (i = 0; i < cpus_removed; i++)
 697                         dlpar_cpu_add(cpu_drcs[i]);
 698
 699                 rc = -EINVAL;
 700         } else {
 701                 rc = 0;
 702         }
 703
 704         kfree(cpu_drcs);
 705         return rc;
 706 }
 707
 708 static int find_dlpar_cpus_to_add(u32 *cpu_drcs, u32 cpus_to_add)
 709 {
 710         struct device_node *parent;
 711         int cpus_found = 0;
 712         int index, rc;
 713
 714         parent = of_find_node_by_path("/cpus");
 715         if (!parent) {
 716                 pr_warn("Could not find CPU root node in device tree\n");
 717                 kfree(cpu_drcs);
 718                 return -1;
 719         }
 720
 721         /* Search the ibm,drc-indexes array for possible CPU drcs to
 722          * add. Note that the format of the ibm,drc-indexes array is
 723          * the number of entries in the array followed by the array
 724          * of drc values so we start looking at index = 1.
 725          */
 726         index = 1;
 727         while (cpus_found < cpus_to_add) {
 728                 u32 drc;
 729
 730                 rc = of_property_read_u32_index(parent, "ibm,drc-indexes",
 731                                                 index++, &drc);
 732                 if (rc)
 733                         break;
 734
 735                 if (dlpar_cpu_exists(parent, drc))
 736                         continue;
 737
 738                 cpu_drcs[cpus_found++] = drc;
 739         }
 740
 741         of_node_put(parent);
 742         return cpus_found;
 743 }
 744
 745 static int dlpar_cpu_add_by_count(u32 cpus_to_add)
 746 {
 747         u32 *cpu_drcs;
 748         int cpus_added = 0;
 749         int cpus_found;
 750         int i, rc;
 751
 752         pr_debug("Attempting to hot-add %d CPUs\n", cpus_to_add);
 753
 754         cpu_drcs = kcalloc(cpus_to_add, sizeof(*cpu_drcs), GFP_KERNEL);
 755         if (!cpu_drcs)
 756                 return -EINVAL;
 757
 758         cpus_found = find_dlpar_cpus_to_add(cpu_drcs, cpus_to_add);
 759         if (cpus_found < cpus_to_add) {
 760                 pr_warn("Failed to find enough CPUs (%d of %d) to add\n",
 761                         cpus_found, cpus_to_add);
 762                 kfree(cpu_drcs);
 763                 return -EINVAL;
 764         }
 765
 766         for (i = 0; i < cpus_to_add; i++) {
 767                 rc = dlpar_cpu_add(cpu_drcs[i]);
 768                 if (rc)
 769                         break;
 770
 771                 cpus_added++;
 772         }
 773
 774         if (cpus_added < cpus_to_add) {
 775                 pr_warn("CPU hot-add failed, removing any added CPUs\n");
 776
 777                 for (i = 0; i < cpus_added; i++)
 778                         dlpar_cpu_remove_by_index(cpu_drcs[i]);
 779
 780                 rc = -EINVAL;
 781         } else {
 782                 rc = 0;
 783         }
 784
 785         kfree(cpu_drcs);
 786         return rc;
 787 }
 788
 789 int dlpar_cpu(struct pseries_hp_errorlog *hp_elog)
 790 {
 791         u32 count, drc_index;
 792         int rc;
 793
 794         count = hp_elog->_drc_u.drc_count;
 795         drc_index = hp_elog->_drc_u.drc_index;
 796
 797         lock_device_hotplug();
 798
 799         switch (hp_elog->action) {
 800         case PSERIES_HP_ELOG_ACTION_REMOVE:
 801                 if (hp_elog->id_type == PSERIES_HP_ELOG_ID_DRC_COUNT)
 802                         rc = dlpar_cpu_remove_by_count(count);
 803                 else if (hp_elog->id_type == PSERIES_HP_ELOG_ID_DRC_INDEX)
 804                         rc = dlpar_cpu_remove_by_index(drc_index);
 805                 else
 806                         rc = -EINVAL;
 807                 break;
 808         case PSERIES_HP_ELOG_ACTION_ADD:
 809                 if (hp_elog->id_type == PSERIES_HP_ELOG_ID_DRC_COUNT)
 810                         rc = dlpar_cpu_add_by_count(count);
 811                 else if (hp_elog->id_type == PSERIES_HP_ELOG_ID_DRC_INDEX)
 812                         rc = dlpar_cpu_add(drc_index);
 813                 else
 814                         rc = -EINVAL;
 815                 break;
 816         default:
 817                 pr_err("Invalid action (%d) specified\n", hp_elog->action);
 818                 rc = -EINVAL;
 819                 break;
 820         }
 821
 822         unlock_device_hotplug();
 823         return rc;
 824 }
 825
 826 #ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
 827
 828 static ssize_t dlpar_cpu_probe(const char *buf, size_t count)
 829 {
 830         u32 drc_index;
 831         int rc;
 832
 833         rc = kstrtou32(buf, 0, &drc_index);
 834         if (rc)
 835                 return -EINVAL;
 836
 837         rc = dlpar_cpu_add(drc_index);
 838
 839         return rc ? rc : count;
 840 }
 841
 842 static ssize_t dlpar_cpu_release(const char *buf, size_t count)
 843 {
 844         struct device_node *dn;
 845         u32 drc_index;
 846         int rc;
 847
 848         dn = of_find_node_by_path(buf);
 849         if (!dn)
 850                 return -EINVAL;
 851
 852         rc = of_property_read_u32(dn, "ibm,my-drc-index", &drc_index);
 853         if (rc) {
 854                 of_node_put(dn);
 855                 return -EINVAL;
 856         }
 857
 858         rc = dlpar_cpu_remove(dn, drc_index);
 859         of_node_put(dn);
 860
 861         return rc ? rc : count;
 862 }
 863
 864 #endif /* CONFIG_ARCH_CPU_PROBE_RELEASE */
 865
 866 static int pseries_smp_notifier(struct notifier_block *nb,
 867                                 unsigned long action, void *data)
 868 {
 869         struct of_reconfig_data *rd = data;
 870         int err = 0;
 871
 872         switch (action) {
 873         case OF_RECONFIG_ATTACH_NODE:
 874                 err = pseries_add_processor(rd->dn);
 875                 break;
 876         case OF_RECONFIG_DETACH_NODE:
 877                 pseries_remove_processor(rd->dn);
 878                 break;
 879         }
 880         return notifier_from_errno(err);
 881 }
 882
 883 static struct notifier_block pseries_smp_nb = {
 884         .notifier_call = pseries_smp_notifier,
 885 };
 886
 887 #define MAX_CEDE_LATENCY_LEVELS         4
 888 #define CEDE_LATENCY_PARAM_LENGTH       10
 889 #define CEDE_LATENCY_PARAM_MAX_LENGTH   \
 890         (MAX_CEDE_LATENCY_LEVELS * CEDE_LATENCY_PARAM_LENGTH * sizeof(char))
 891 #define CEDE_LATENCY_TOKEN              45
 892
 893 static char cede_parameters[CEDE_LATENCY_PARAM_MAX_LENGTH];
 894
 895 static int parse_cede_parameters(void)
 896 {
 897         memset(cede_parameters, 0, CEDE_LATENCY_PARAM_MAX_LENGTH);
 898         return rtas_call(rtas_token("ibm,get-system-parameter"), 3, 1,
 899                          NULL,
 900                          CEDE_LATENCY_TOKEN,
 901                          __pa(cede_parameters),
 902                          CEDE_LATENCY_PARAM_MAX_LENGTH);
 903 }
 904
 905 static int __init pseries_cpu_hotplug_init(void)
 906 {
 907         int cpu;
 908         int qcss_tok;
 909
 910 #ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
 911         ppc_md.cpu_probe = dlpar_cpu_probe;
 912         ppc_md.cpu_release = dlpar_cpu_release;
 913 #endif /* CONFIG_ARCH_CPU_PROBE_RELEASE */
 914
 915         rtas_stop_self_token = rtas_token("stop-self");
 916         qcss_tok = rtas_token("query-cpu-stopped-state");
 917
 918         if (rtas_stop_self_token == RTAS_UNKNOWN_SERVICE ||
 919                         qcss_tok == RTAS_UNKNOWN_SERVICE) {
 920                 printk(KERN_INFO "CPU Hotplug not supported by firmware "
 921                                 "- disabling.\n");
 922                 return 0;
 923         }
 924
 925         ppc_md.cpu_die = pseries_mach_cpu_die;
 926         smp_ops->cpu_disable = pseries_cpu_disable;
 927         smp_ops->cpu_die = pseries_cpu_die;
 928
 929         /* Processors can be added/removed only on LPAR */
 930         if (firmware_has_feature(FW_FEATURE_LPAR)) {
 931                 of_reconfig_notifier_register(&pseries_smp_nb);
 932                 cpu_maps_update_begin();
 933                 if (cede_offline_enabled && parse_cede_parameters() == 0) {
 934                         default_offline_state = CPU_STATE_INACTIVE;
 935                         for_each_online_cpu(cpu)
 936                                 set_default_offline_state(cpu);
 937                 }
 938                 cpu_maps_update_done();
 939         }
 940
 941         return 0;
 942 }
 943 machine_arch_initcall(pseries, pseries_cpu_hotplug_init);