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/cpu.h>
  28 #include <linux/of.h>
  29 #include <linux/slab.h>
  30 #include <asm/prom.h>
  31 #include <asm/rtas.h>
  32 #include <asm/firmware.h>
  33 #include <asm/machdep.h>
  34 #include <asm/vdso_datapage.h>
  35 #include <asm/xics.h>
  36 #include <asm/plpar_wrappers.h>
  37
  38 #include "pseries.h"
  39 #include "offline_states.h"
  40
  41 /* This version can't take the spinlock, because it never returns */
  42 static int rtas_stop_self_token = RTAS_UNKNOWN_SERVICE;
  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 bool cede_offline_enabled __read_mostly = true;
  51
  52 /*
  53  * Enable/disable cede_offline when available.
  54  */
  55 static int __init setup_cede_offline(char *str)
  56 {
  57         return (kstrtobool(str, &cede_offline_enabled) == 0);
  58 }
  59
  60 __setup("cede_offline=", setup_cede_offline);
  61
  62 enum cpu_state_vals get_cpu_current_state(int cpu)
  63 {
  64         return per_cpu(current_state, cpu);
  65 }
  66
  67 void set_cpu_current_state(int cpu, enum cpu_state_vals state)
  68 {
  69         per_cpu(current_state, cpu) = state;
  70 }
  71
  72 enum cpu_state_vals get_preferred_offline_state(int cpu)
  73 {
  74         return per_cpu(preferred_offline_state, cpu);
  75 }
  76
  77 void set_preferred_offline_state(int cpu, enum cpu_state_vals state)
  78 {
  79         per_cpu(preferred_offline_state, cpu) = state;
  80 }
  81
  82 void set_default_offline_state(int cpu)
  83 {
  84         per_cpu(preferred_offline_state, cpu) = default_offline_state;
  85 }
  86
  87 static void rtas_stop_self(void)
  88 {
  89         static struct rtas_args args;
  90
  91         local_irq_disable();
  92
  93         BUG_ON(rtas_stop_self_token == RTAS_UNKNOWN_SERVICE);
  94
  95         printk("cpu %u (hwid %u) Ready to die...\n",
  96                smp_processor_id(), hard_smp_processor_id());
  97
  98         rtas_call_unlocked(&args, rtas_stop_self_token, 0, 1, NULL);
  99
 100         panic("Alas, I survived.\n");
 101 }
 102
 103 static void pseries_mach_cpu_die(void)
 104 {
 105         unsigned int cpu = smp_processor_id();
 106         unsigned int hwcpu = hard_smp_processor_id();
 107         u8 cede_latency_hint = 0;
 108
 109         local_irq_disable();
 110         idle_task_exit();
 111         xics_teardown_cpu();
 112
 113         if (get_preferred_offline_state(cpu) == CPU_STATE_INACTIVE) {
 114                 set_cpu_current_state(cpu, CPU_STATE_INACTIVE);
 115                 if (ppc_md.suspend_disable_cpu)
 116                         ppc_md.suspend_disable_cpu();
 117
 118                 cede_latency_hint = 2;
 119
 120                 get_lppaca()->idle = 1;
 121                 if (!lppaca_shared_proc(get_lppaca()))
 122                         get_lppaca()->donate_dedicated_cpu = 1;
 123
 124                 while (get_preferred_offline_state(cpu) == CPU_STATE_INACTIVE) {
 125                         while (!prep_irq_for_idle()) {
 126                                 local_irq_enable();
 127                                 local_irq_disable();
 128                         }
 129
 130                         extended_cede_processor(cede_latency_hint);
 131                 }
 132
 133                 local_irq_disable();
 134
 135                 if (!lppaca_shared_proc(get_lppaca()))
 136                         get_lppaca()->donate_dedicated_cpu = 0;
 137                 get_lppaca()->idle = 0;
 138
 139                 if (get_preferred_offline_state(cpu) == CPU_STATE_ONLINE) {
 140                         unregister_slb_shadow(hwcpu);
 141
 142                         hard_irq_disable();
 143                         /*
 144                          * Call to start_secondary_resume() will not return.
 145                          * Kernel stack will be reset and start_secondary()
 146                          * will be called to continue the online operation.
 147                          */
 148                         start_secondary_resume();
 149                 }
 150         }
 151
 152         /* Requested state is CPU_STATE_OFFLINE at this point */
 153         WARN_ON(get_preferred_offline_state(cpu) != CPU_STATE_OFFLINE);
 154
 155         set_cpu_current_state(cpu, CPU_STATE_OFFLINE);
 156         unregister_slb_shadow(hwcpu);
 157         rtas_stop_self();
 158
 159         /* Should never get here... */
 160         BUG();
 161         for(;;);
 162 }
 163
 164 static int pseries_cpu_disable(void)
 165 {
 166         int cpu = smp_processor_id();
 167
 168         set_cpu_online(cpu, false);
 169         vdso_data->processorCount--;
 170
 171         /*fix boot_cpuid here*/
 172         if (cpu == boot_cpuid)
 173                 boot_cpuid = cpumask_any(cpu_online_mask);
 174
 175         /* FIXME: abstract this to not be platform specific later on */
 176         xics_migrate_irqs_away();
 177         return 0;
 178 }
 179
 180 /*
 181  * pseries_cpu_die: Wait for the cpu to die.
 182  * @cpu: logical processor id of the CPU whose death we're awaiting.
 183  *
 184  * This function is called from the context of the thread which is performing
 185  * the cpu-offline. Here we wait for long enough to allow the cpu in question
 186  * to self-destroy so that the cpu-offline thread can send the CPU_DEAD
 187  * notifications.
 188  *
 189  * OTOH, pseries_mach_cpu_die() is called by the @cpu when it wants to
 190  * self-destruct.
 191  */
 192 static void pseries_cpu_die(unsigned int cpu)
 193 {
 194         int tries;
 195         int cpu_status = 1;
 196         unsigned int pcpu = get_hard_smp_processor_id(cpu);
 197
 198         if (get_preferred_offline_state(cpu) == CPU_STATE_INACTIVE) {
 199                 cpu_status = 1;
 200                 for (tries = 0; tries < 5000; tries++) {
 201                         if (get_cpu_current_state(cpu) == CPU_STATE_INACTIVE) {
 202                                 cpu_status = 0;
 203                                 break;
 204                         }
 205                         msleep(1);
 206                 }
 207         } else if (get_preferred_offline_state(cpu) == CPU_STATE_OFFLINE) {
 208
 209                 for (tries = 0; tries < 25; tries++) {
 210                         cpu_status = smp_query_cpu_stopped(pcpu);
 211                         if (cpu_status == QCSS_STOPPED ||
 212                             cpu_status == QCSS_HARDWARE_ERROR)
 213                                 break;
 214                         cpu_relax();
 215                 }
 216         }
 217
 218         if (cpu_status != 0) {
 219                 printk("Querying DEAD? cpu %i (%i) shows %i\n",
 220                        cpu, pcpu, cpu_status);
 221         }
 222
 223         /* Isolation and deallocation are definitely done by
 224          * drslot_chrp_cpu.  If they were not they would be
 225          * done here.  Change isolate state to Isolate and
 226          * change allocation-state to Unusable.
 227          */
 228         paca[cpu].cpu_start = 0;
 229 }
 230
 231 /*
 232  * Update cpu_present_mask and paca(s) for a new cpu node.  The wrinkle
 233  * here is that a cpu device node may represent up to two logical cpus
 234  * in the SMT case.  We must honor the assumption in other code that
 235  * the logical ids for sibling SMT threads x and y are adjacent, such
 236  * that x^1 == y and y^1 == x.
 237  */
 238 static int pseries_add_processor(struct device_node *np)
 239 {
 240         unsigned int cpu;
 241         cpumask_var_t candidate_mask, tmp;
 242         int err = -ENOSPC, len, nthreads, i;
 243         const __be32 *intserv;
 244
 245         intserv = of_get_property(np, "ibm,ppc-interrupt-server#s", &len);
 246         if (!intserv)
 247                 return 0;
 248
 249         zalloc_cpumask_var(&candidate_mask, GFP_KERNEL);
 250         zalloc_cpumask_var(&tmp, GFP_KERNEL);
 251
 252         nthreads = len / sizeof(u32);
 253         for (i = 0; i < nthreads; i++)
 254                 cpumask_set_cpu(i, tmp);
 255
 256         cpu_maps_update_begin();
 257
 258         BUG_ON(!cpumask_subset(cpu_present_mask, cpu_possible_mask));
 259
 260         /* Get a bitmap of unoccupied slots. */
 261         cpumask_xor(candidate_mask, cpu_possible_mask, cpu_present_mask);
 262         if (cpumask_empty(candidate_mask)) {
 263                 /* If we get here, it most likely means that NR_CPUS is
 264                  * less than the partition's max processors setting.
 265                  */
 266                 printk(KERN_ERR "Cannot add cpu %s; this system configuration"
 267                        " supports %d logical cpus.\n", np->full_name,
 268                        num_possible_cpus());
 269                 goto out_unlock;
 270         }
 271
 272         while (!cpumask_empty(tmp))
 273                 if (cpumask_subset(tmp, candidate_mask))
 274                         /* Found a range where we can insert the new cpu(s) */
 275                         break;
 276                 else
 277                         cpumask_shift_left(tmp, tmp, nthreads);
 278
 279         if (cpumask_empty(tmp)) {
 280                 printk(KERN_ERR "Unable to find space in cpu_present_mask for"
 281                        " processor %s with %d thread(s)\n", np->name,
 282                        nthreads);
 283                 goto out_unlock;
 284         }
 285
 286         for_each_cpu(cpu, tmp) {
 287                 BUG_ON(cpu_present(cpu));
 288                 set_cpu_present(cpu, true);
 289                 set_hard_smp_processor_id(cpu, be32_to_cpu(*intserv++));
 290         }
 291         err = 0;
 292 out_unlock:
 293         cpu_maps_update_done();
 294         free_cpumask_var(candidate_mask);
 295         free_cpumask_var(tmp);
 296         return err;
 297 }
 298
 299 /*
 300  * Update the present map for a cpu node which is going away, and set
 301  * the hard id in the paca(s) to -1 to be consistent with boot time
 302  * convention for non-present cpus.
 303  */
 304 static void pseries_remove_processor(struct device_node *np)
 305 {
 306         unsigned int cpu;
 307         int len, nthreads, i;
 308         const __be32 *intserv;
 309         u32 thread;
 310
 311         intserv = of_get_property(np, "ibm,ppc-interrupt-server#s", &len);
 312         if (!intserv)
 313                 return;
 314
 315         nthreads = len / sizeof(u32);
 316
 317         cpu_maps_update_begin();
 318         for (i = 0; i < nthreads; i++) {
 319                 thread = be32_to_cpu(intserv[i]);
 320                 for_each_present_cpu(cpu) {
 321                         if (get_hard_smp_processor_id(cpu) != thread)
 322                                 continue;
 323                         BUG_ON(cpu_online(cpu));
 324                         set_cpu_present(cpu, false);
 325                         set_hard_smp_processor_id(cpu, -1);
 326                         break;
 327                 }
 328                 if (cpu >= nr_cpu_ids)
 329                         printk(KERN_WARNING "Could not find cpu to remove "
 330                                "with physical id 0x%x\n", thread);
 331         }
 332         cpu_maps_update_done();
 333 }
 334
 335 static int dlpar_online_cpu(struct device_node *dn)
 336 {
 337         int rc = 0;
 338         unsigned int cpu;
 339         int len, nthreads, i;
 340         const __be32 *intserv;
 341         u32 thread;
 342
 343         intserv = of_get_property(dn, "ibm,ppc-interrupt-server#s", &len);
 344         if (!intserv)
 345                 return -EINVAL;
 346
 347         nthreads = len / sizeof(u32);
 348
 349         cpu_maps_update_begin();
 350         for (i = 0; i < nthreads; i++) {
 351                 thread = be32_to_cpu(intserv[i]);
 352                 for_each_present_cpu(cpu) {
 353                         if (get_hard_smp_processor_id(cpu) != thread)
 354                                 continue;
 355                         BUG_ON(get_cpu_current_state(cpu)
 356                                         != CPU_STATE_OFFLINE);
 357                         cpu_maps_update_done();
 358                         rc = device_online(get_cpu_device(cpu));
 359                         if (rc)
 360                                 goto out;
 361                         cpu_maps_update_begin();
 362
 363                         break;
 364                 }
 365                 if (cpu == num_possible_cpus())
 366                         printk(KERN_WARNING "Could not find cpu to online "
 367                                "with physical id 0x%x\n", thread);
 368         }
 369         cpu_maps_update_done();
 370
 371 out:
 372         return rc;
 373
 374 }
 375
 376 static bool dlpar_cpu_exists(struct device_node *parent, u32 drc_index)
 377 {
 378         struct device_node *child = NULL;
 379         u32 my_drc_index;
 380         bool found;
 381         int rc;
 382
 383         /* Assume cpu doesn't exist */
 384         found = false;
 385
 386         for_each_child_of_node(parent, child) {
 387                 rc = of_property_read_u32(child, "ibm,my-drc-index",
 388                                           &my_drc_index);
 389                 if (rc)
 390                         continue;
 391
 392                 if (my_drc_index == drc_index) {
 393                         of_node_put(child);
 394                         found = true;
 395                         break;
 396                 }
 397         }
 398
 399         return found;
 400 }
 401
 402 static bool valid_cpu_drc_index(struct device_node *parent, u32 drc_index)
 403 {
 404         bool found = false;
 405         int rc, index;
 406
 407         index = 0;
 408         while (!found) {
 409                 u32 drc;
 410
 411                 rc = of_property_read_u32_index(parent, "ibm,drc-indexes",
 412                                                 index++, &drc);
 413                 if (rc)
 414                         break;
 415
 416                 if (drc == drc_index)
 417                         found = true;
 418         }
 419
 420         return found;
 421 }
 422
 423 static ssize_t dlpar_cpu_add(u32 drc_index)
 424 {
 425         struct device_node *dn, *parent;
 426         int rc, saved_rc;
 427
 428         pr_debug("Attempting to add CPU, drc index: %x\n", drc_index);
 429
 430         parent = of_find_node_by_path("/cpus");
 431         if (!parent) {
 432                 pr_warn("Failed to find CPU root node \"/cpus\"\n");
 433                 return -ENODEV;
 434         }
 435
 436         if (dlpar_cpu_exists(parent, drc_index)) {
 437                 of_node_put(parent);
 438                 pr_warn("CPU with drc index %x already exists\n", drc_index);
 439                 return -EINVAL;
 440         }
 441
 442         if (!valid_cpu_drc_index(parent, drc_index)) {
 443                 of_node_put(parent);
 444                 pr_warn("Cannot find CPU (drc index %x) to add.\n", drc_index);
 445                 return -EINVAL;
 446         }
 447
 448         rc = dlpar_acquire_drc(drc_index);
 449         if (rc) {
 450                 pr_warn("Failed to acquire DRC, rc: %d, drc index: %x\n",
 451                         rc, drc_index);
 452                 of_node_put(parent);
 453                 return -EINVAL;
 454         }
 455
 456         dn = dlpar_configure_connector(cpu_to_be32(drc_index), parent);
 457         of_node_put(parent);
 458         if (!dn) {
 459                 pr_warn("Failed call to configure-connector, drc index: %x\n",
 460                         drc_index);
 461                 dlpar_release_drc(drc_index);
 462                 return -EINVAL;
 463         }
 464
 465         rc = dlpar_attach_node(dn);
 466         if (rc) {
 467                 saved_rc = rc;
 468                 pr_warn("Failed to attach node %s, rc: %d, drc index: %x\n",
 469                         dn->name, rc, drc_index);
 470
 471                 rc = dlpar_release_drc(drc_index);
 472                 if (!rc)
 473                         dlpar_free_cc_nodes(dn);
 474
 475                 return saved_rc;
 476         }
 477
 478         rc = dlpar_online_cpu(dn);
 479         if (rc) {
 480                 saved_rc = rc;
 481                 pr_warn("Failed to online cpu %s, rc: %d, drc index: %x\n",
 482                         dn->name, rc, drc_index);
 483
 484                 rc = dlpar_detach_node(dn);
 485                 if (!rc)
 486                         dlpar_release_drc(drc_index);
 487
 488                 return saved_rc;
 489         }
 490
 491         pr_debug("Successfully added CPU %s, drc index: %x\n", dn->name,
 492                  drc_index);
 493         return rc;
 494 }
 495
 496 static int dlpar_offline_cpu(struct device_node *dn)
 497 {
 498         int rc = 0;
 499         unsigned int cpu;
 500         int len, nthreads, i;
 501         const __be32 *intserv;
 502         u32 thread;
 503
 504         intserv = of_get_property(dn, "ibm,ppc-interrupt-server#s", &len);
 505         if (!intserv)
 506                 return -EINVAL;
 507
 508         nthreads = len / sizeof(u32);
 509
 510         cpu_maps_update_begin();
 511         for (i = 0; i < nthreads; i++) {
 512                 thread = be32_to_cpu(intserv[i]);
 513                 for_each_present_cpu(cpu) {
 514                         if (get_hard_smp_processor_id(cpu) != thread)
 515                                 continue;
 516
 517                         if (get_cpu_current_state(cpu) == CPU_STATE_OFFLINE)
 518                                 break;
 519
 520                         if (get_cpu_current_state(cpu) == CPU_STATE_ONLINE) {
 521                                 set_preferred_offline_state(cpu,
 522                                                             CPU_STATE_OFFLINE);
 523                                 cpu_maps_update_done();
 524                                 rc = device_offline(get_cpu_device(cpu));
 525                                 if (rc)
 526                                         goto out;
 527                                 cpu_maps_update_begin();
 528                                 break;
 529
 530                         }
 531
 532                         /*
 533                          * The cpu is in CPU_STATE_INACTIVE.
 534                          * Upgrade it's state to CPU_STATE_OFFLINE.
 535                          */
 536                         set_preferred_offline_state(cpu, CPU_STATE_OFFLINE);
 537                         BUG_ON(plpar_hcall_norets(H_PROD, thread)
 538                                                                 != H_SUCCESS);
 539                         __cpu_die(cpu);
 540                         break;
 541                 }
 542                 if (cpu == num_possible_cpus())
 543                         printk(KERN_WARNING "Could not find cpu to offline with physical id 0x%x\n", thread);
 544         }
 545         cpu_maps_update_done();
 546
 547 out:
 548         return rc;
 549
 550 }
 551
 552 static ssize_t dlpar_cpu_remove(struct device_node *dn, u32 drc_index)
 553 {
 554         int rc;
 555
 556         pr_debug("Attemping to remove CPU %s, drc index: %x\n",
 557                  dn->name, drc_index);
 558
 559         rc = dlpar_offline_cpu(dn);
 560         if (rc) {
 561                 pr_warn("Failed to offline CPU %s, rc: %d\n", dn->name, rc);
 562                 return -EINVAL;
 563         }
 564
 565         rc = dlpar_release_drc(drc_index);
 566         if (rc) {
 567                 pr_warn("Failed to release drc (%x) for CPU %s, rc: %d\n",
 568                         drc_index, dn->name, rc);
 569                 dlpar_online_cpu(dn);
 570                 return rc;
 571         }
 572
 573         rc = dlpar_detach_node(dn);
 574         if (rc) {
 575                 int saved_rc = rc;
 576
 577                 pr_warn("Failed to detach CPU %s, rc: %d", dn->name, rc);
 578
 579                 rc = dlpar_acquire_drc(drc_index);
 580                 if (!rc)
 581                         dlpar_online_cpu(dn);
 582
 583                 return saved_rc;
 584         }
 585
 586         pr_debug("Successfully removed CPU, drc index: %x\n", drc_index);
 587         return 0;
 588 }
 589
 590 static struct device_node *cpu_drc_index_to_dn(u32 drc_index)
 591 {
 592         struct device_node *dn;
 593         u32 my_index;
 594         int rc;
 595
 596         for_each_node_by_type(dn, "cpu") {
 597                 rc = of_property_read_u32(dn, "ibm,my-drc-index", &my_index);
 598                 if (rc)
 599                         continue;
 600
 601                 if (my_index == drc_index)
 602                         break;
 603         }
 604
 605         return dn;
 606 }
 607
 608 static int dlpar_cpu_remove_by_index(u32 drc_index)
 609 {
 610         struct device_node *dn;
 611         int rc;
 612
 613         dn = cpu_drc_index_to_dn(drc_index);
 614         if (!dn) {
 615                 pr_warn("Cannot find CPU (drc index %x) to remove\n",
 616                         drc_index);
 617                 return -ENODEV;
 618         }
 619
 620         rc = dlpar_cpu_remove(dn, drc_index);
 621         of_node_put(dn);
 622         return rc;
 623 }
 624
 625 static int find_dlpar_cpus_to_remove(u32 *cpu_drcs, int cpus_to_remove)
 626 {
 627         struct device_node *dn;
 628         int cpus_found = 0;
 629         int rc;
 630
 631         /* We want to find cpus_to_remove + 1 CPUs to ensure we do not
 632          * remove the last CPU.
 633          */
 634         for_each_node_by_type(dn, "cpu") {
 635                 cpus_found++;
 636
 637                 if (cpus_found > cpus_to_remove) {
 638                         of_node_put(dn);
 639                         break;
 640                 }
 641
 642                 /* Note that cpus_found is always 1 ahead of the index
 643                  * into the cpu_drcs array, so we use cpus_found - 1
 644                  */
 645                 rc = of_property_read_u32(dn, "ibm,my-drc-index",
 646                                           &cpu_drcs[cpus_found - 1]);
 647                 if (rc) {
 648                         pr_warn("Error occurred getting drc-index for %s\n",
 649                                 dn->name);
 650                         of_node_put(dn);
 651                         return -1;
 652                 }
 653         }
 654
 655         if (cpus_found < cpus_to_remove) {
 656                 pr_warn("Failed to find enough CPUs (%d of %d) to remove\n",
 657                         cpus_found, cpus_to_remove);
 658         } else if (cpus_found == cpus_to_remove) {
 659                 pr_warn("Cannot remove all CPUs\n");
 660         }
 661
 662         return cpus_found;
 663 }
 664
 665 static int dlpar_cpu_remove_by_count(u32 cpus_to_remove)
 666 {
 667         u32 *cpu_drcs;
 668         int cpus_found;
 669         int cpus_removed = 0;
 670         int i, rc;
 671
 672         pr_debug("Attempting to hot-remove %d CPUs\n", cpus_to_remove);
 673
 674         cpu_drcs = kcalloc(cpus_to_remove, sizeof(*cpu_drcs), GFP_KERNEL);
 675         if (!cpu_drcs)
 676                 return -EINVAL;
 677
 678         cpus_found = find_dlpar_cpus_to_remove(cpu_drcs, cpus_to_remove);
 679         if (cpus_found <= cpus_to_remove) {
 680                 kfree(cpu_drcs);
 681                 return -EINVAL;
 682         }
 683
 684         for (i = 0; i < cpus_to_remove; i++) {
 685                 rc = dlpar_cpu_remove_by_index(cpu_drcs[i]);
 686                 if (rc)
 687                         break;
 688
 689                 cpus_removed++;
 690         }
 691
 692         if (cpus_removed != cpus_to_remove) {
 693                 pr_warn("CPU hot-remove failed, adding back removed CPUs\n");
 694
 695                 for (i = 0; i < cpus_removed; i++)
 696                         dlpar_cpu_add(cpu_drcs[i]);
 697
 698                 rc = -EINVAL;
 699         } else {
 700                 rc = 0;
 701         }
 702
 703         kfree(cpu_drcs);
 704         return rc;
 705 }
 706
 707 static int find_dlpar_cpus_to_add(u32 *cpu_drcs, u32 cpus_to_add)
 708 {
 709         struct device_node *parent;
 710         int cpus_found = 0;
 711         int index, rc;
 712
 713         parent = of_find_node_by_path("/cpus");
 714         if (!parent) {
 715                 pr_warn("Could not find CPU root node in device tree\n");
 716                 kfree(cpu_drcs);
 717                 return -1;
 718         }
 719
 720         /* Search the ibm,drc-indexes array for possible CPU drcs to
 721          * add. Note that the format of the ibm,drc-indexes array is
 722          * the number of entries in the array followed by the array
 723          * of drc values so we start looking at index = 1.
 724          */
 725         index = 1;
 726         while (cpus_found < cpus_to_add) {
 727                 u32 drc;
 728
 729                 rc = of_property_read_u32_index(parent, "ibm,drc-indexes",
 730                                                 index++, &drc);
 731                 if (rc)
 732                         break;
 733
 734                 if (dlpar_cpu_exists(parent, drc))
 735                         continue;
 736
 737                 cpu_drcs[cpus_found++] = drc;
 738         }
 739
 740         of_node_put(parent);
 741         return cpus_found;
 742 }
 743
 744 static int dlpar_cpu_add_by_count(u32 cpus_to_add)
 745 {
 746         u32 *cpu_drcs;
 747         int cpus_added = 0;
 748         int cpus_found;
 749         int i, rc;
 750
 751         pr_debug("Attempting to hot-add %d CPUs\n", cpus_to_add);
 752
 753         cpu_drcs = kcalloc(cpus_to_add, sizeof(*cpu_drcs), GFP_KERNEL);
 754         if (!cpu_drcs)
 755                 return -EINVAL;
 756
 757         cpus_found = find_dlpar_cpus_to_add(cpu_drcs, cpus_to_add);
 758         if (cpus_found < cpus_to_add) {
 759                 pr_warn("Failed to find enough CPUs (%d of %d) to add\n",
 760                         cpus_found, cpus_to_add);
 761                 kfree(cpu_drcs);
 762                 return -EINVAL;
 763         }
 764
 765         for (i = 0; i < cpus_to_add; i++) {
 766                 rc = dlpar_cpu_add(cpu_drcs[i]);
 767                 if (rc)
 768                         break;
 769
 770                 cpus_added++;
 771         }
 772
 773         if (cpus_added < cpus_to_add) {
 774                 pr_warn("CPU hot-add failed, removing any added CPUs\n");
 775
 776                 for (i = 0; i < cpus_added; i++)
 777                         dlpar_cpu_remove_by_index(cpu_drcs[i]);
 778
 779                 rc = -EINVAL;
 780         } else {
 781                 rc = 0;
 782         }
 783
 784         kfree(cpu_drcs);
 785         return rc;
 786 }
 787
 788 int dlpar_cpu(struct pseries_hp_errorlog *hp_elog)
 789 {
 790         u32 count, drc_index;
 791         int rc;
 792
 793         count = hp_elog->_drc_u.drc_count;
 794         drc_index = hp_elog->_drc_u.drc_index;
 795
 796         lock_device_hotplug();
 797
 798         switch (hp_elog->action) {
 799         case PSERIES_HP_ELOG_ACTION_REMOVE:
 800                 if (hp_elog->id_type == PSERIES_HP_ELOG_ID_DRC_COUNT)
 801                         rc = dlpar_cpu_remove_by_count(count);
 802                 else if (hp_elog->id_type == PSERIES_HP_ELOG_ID_DRC_INDEX)
 803                         rc = dlpar_cpu_remove_by_index(drc_index);
 804                 else
 805                         rc = -EINVAL;
 806                 break;
 807         case PSERIES_HP_ELOG_ACTION_ADD:
 808                 if (hp_elog->id_type == PSERIES_HP_ELOG_ID_DRC_COUNT)
 809                         rc = dlpar_cpu_add_by_count(count);
 810                 else if (hp_elog->id_type == PSERIES_HP_ELOG_ID_DRC_INDEX)
 811                         rc = dlpar_cpu_add(drc_index);
 812                 else
 813                         rc = -EINVAL;
 814                 break;
 815         default:
 816                 pr_err("Invalid action (%d) specified\n", hp_elog->action);
 817                 rc = -EINVAL;
 818                 break;
 819         }
 820
 821         unlock_device_hotplug();
 822         return rc;
 823 }
 824
 825 #ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
 826
 827 static ssize_t dlpar_cpu_probe(const char *buf, size_t count)
 828 {
 829         u32 drc_index;
 830         int rc;
 831
 832         rc = kstrtou32(buf, 0, &drc_index);
 833         if (rc)
 834                 return -EINVAL;
 835
 836         rc = dlpar_cpu_add(drc_index);
 837
 838         return rc ? rc : count;
 839 }
 840
 841 static ssize_t dlpar_cpu_release(const char *buf, size_t count)
 842 {
 843         struct device_node *dn;
 844         u32 drc_index;
 845         int rc;
 846
 847         dn = of_find_node_by_path(buf);
 848         if (!dn)
 849                 return -EINVAL;
 850
 851         rc = of_property_read_u32(dn, "ibm,my-drc-index", &drc_index);
 852         if (rc) {
 853                 of_node_put(dn);
 854                 return -EINVAL;
 855         }
 856
 857         rc = dlpar_cpu_remove(dn, drc_index);
 858         of_node_put(dn);
 859
 860         return rc ? rc : count;
 861 }
 862
 863 #endif /* CONFIG_ARCH_CPU_PROBE_RELEASE */
 864
 865 static int pseries_smp_notifier(struct notifier_block *nb,
 866                                 unsigned long action, void *data)
 867 {
 868         struct of_reconfig_data *rd = data;
 869         int err = 0;
 870
 871         switch (action) {
 872         case OF_RECONFIG_ATTACH_NODE:
 873                 err = pseries_add_processor(rd->dn);
 874                 break;
 875         case OF_RECONFIG_DETACH_NODE:
 876                 pseries_remove_processor(rd->dn);
 877                 break;
 878         }
 879         return notifier_from_errno(err);
 880 }
 881
 882 static struct notifier_block pseries_smp_nb = {
 883         .notifier_call = pseries_smp_notifier,
 884 };
 885
 886 #define MAX_CEDE_LATENCY_LEVELS         4
 887 #define CEDE_LATENCY_PARAM_LENGTH       10
 888 #define CEDE_LATENCY_PARAM_MAX_LENGTH   \
 889         (MAX_CEDE_LATENCY_LEVELS * CEDE_LATENCY_PARAM_LENGTH * sizeof(char))
 890 #define CEDE_LATENCY_TOKEN              45
 891
 892 static char cede_parameters[CEDE_LATENCY_PARAM_MAX_LENGTH];
 893
 894 static int parse_cede_parameters(void)
 895 {
 896         memset(cede_parameters, 0, CEDE_LATENCY_PARAM_MAX_LENGTH);
 897         return rtas_call(rtas_token("ibm,get-system-parameter"), 3, 1,
 898                          NULL,
 899                          CEDE_LATENCY_TOKEN,
 900                          __pa(cede_parameters),
 901                          CEDE_LATENCY_PARAM_MAX_LENGTH);
 902 }
 903
 904 static int __init pseries_cpu_hotplug_init(void)
 905 {
 906         int cpu;
 907         int qcss_tok;
 908
 909 #ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
 910         ppc_md.cpu_probe = dlpar_cpu_probe;
 911         ppc_md.cpu_release = dlpar_cpu_release;
 912 #endif /* CONFIG_ARCH_CPU_PROBE_RELEASE */
 913
 914         rtas_stop_self_token = rtas_token("stop-self");
 915         qcss_tok = rtas_token("query-cpu-stopped-state");
 916
 917         if (rtas_stop_self_token == RTAS_UNKNOWN_SERVICE ||
 918                         qcss_tok == RTAS_UNKNOWN_SERVICE) {
 919                 printk(KERN_INFO "CPU Hotplug not supported by firmware "
 920                                 "- disabling.\n");
 921                 return 0;
 922         }
 923
 924         ppc_md.cpu_die = pseries_mach_cpu_die;
 925         smp_ops->cpu_disable = pseries_cpu_disable;
 926         smp_ops->cpu_die = pseries_cpu_die;
 927
 928         /* Processors can be added/removed only on LPAR */
 929         if (firmware_has_feature(FW_FEATURE_LPAR)) {
 930                 of_reconfig_notifier_register(&pseries_smp_nb);
 931                 cpu_maps_update_begin();
 932                 if (cede_offline_enabled && parse_cede_parameters() == 0) {
 933                         default_offline_state = CPU_STATE_INACTIVE;
 934                         for_each_online_cpu(cpu)
 935                                 set_default_offline_state(cpu);
 936                 }
 937                 cpu_maps_update_done();
 938         }
 939
 940         return 0;
 941 }
 942 machine_arch_initcall(pseries, pseries_cpu_hotplug_init);