arch/s390/kernel/smp.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *  SMP related functions
   4  *
   5  *    Copyright IBM Corp. 1999, 2012
   6  *    Author(s): Denis Joseph Barrow,
   7  *               Martin Schwidefsky <schwidefsky@de.ibm.com>,
   8  *               Heiko Carstens <heiko.carstens@de.ibm.com>,
   9  *
  10  *  based on other smp stuff by
  11  *    (c) 1995 Alan Cox, CymruNET Ltd  <alan@cymru.net>
  12  *    (c) 1998 Ingo Molnar
  13  *
  14  * The code outside of smp.c uses logical cpu numbers, only smp.c does
  15  * the translation of logical to physical cpu ids. All new code that
  16  * operates on physical cpu numbers needs to go into smp.c.
  17  */
  18
  19 #define KMSG_COMPONENT "cpu"
  20 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
  21
  22 #include <linux/workqueue.h>
  23 #include <linux/memblock.h>
  24 #include <linux/export.h>
  25 #include <linux/init.h>
  26 #include <linux/mm.h>
  27 #include <linux/err.h>
  28 #include <linux/spinlock.h>
  29 #include <linux/kernel_stat.h>
  30 #include <linux/delay.h>
  31 #include <linux/interrupt.h>
  32 #include <linux/irqflags.h>
  33 #include <linux/cpu.h>
  34 #include <linux/slab.h>
  35 #include <linux/sched/hotplug.h>
  36 #include <linux/sched/task_stack.h>
  37 #include <linux/crash_dump.h>
  38 #include <linux/kprobes.h>
  39 #include <asm/asm-offsets.h>
  40 #include <asm/diag.h>
  41 #include <asm/switch_to.h>
  42 #include <asm/facility.h>
  43 #include <asm/ipl.h>
  44 #include <asm/setup.h>
  45 #include <asm/irq.h>
  46 #include <asm/tlbflush.h>
  47 #include <asm/vtimer.h>
  48 #include <asm/lowcore.h>
  49 #include <asm/sclp.h>
  50 #include <asm/vdso.h>
  51 #include <asm/debug.h>
  52 #include <asm/os_info.h>
  53 #include <asm/sigp.h>
  54 #include <asm/idle.h>
  55 #include <asm/nmi.h>
  56 #include <asm/stacktrace.h>
  57 #include <asm/topology.h>
  58 #include "entry.h"
  59
  60 enum {
  61         ec_schedule = 0,
  62         ec_call_function_single,
  63         ec_stop_cpu,
  64 };
  65
  66 enum {
  67         CPU_STATE_STANDBY,
  68         CPU_STATE_CONFIGURED,
  69 };
  70
  71 static DEFINE_PER_CPU(struct cpu *, cpu_device);
  72
  73 struct pcpu {
  74         struct lowcore *lowcore;        /* lowcore page(s) for the cpu */
  75         unsigned long ec_mask;          /* bit mask for ec_xxx functions */
  76         unsigned long ec_clk;           /* sigp timestamp for ec_xxx */
  77         signed char state;              /* physical cpu state */
  78         signed char polarization;       /* physical polarization */
  79         u16 address;                    /* physical cpu address */
  80 };
  81
  82 static u8 boot_core_type;
  83 static struct pcpu pcpu_devices[NR_CPUS];
  84
  85 unsigned int smp_cpu_mt_shift;
  86 EXPORT_SYMBOL(smp_cpu_mt_shift);
  87
  88 unsigned int smp_cpu_mtid;
  89 EXPORT_SYMBOL(smp_cpu_mtid);
  90
  91 #ifdef CONFIG_CRASH_DUMP
  92 __vector128 __initdata boot_cpu_vector_save_area[__NUM_VXRS];
  93 #endif
  94
  95 static unsigned int smp_max_threads __initdata = -1U;
  96
  97 static int __init early_nosmt(char *s)
  98 {
  99         smp_max_threads = 1;
 100         return 0;
 101 }
 102 early_param("nosmt", early_nosmt);
 103
 104 static int __init early_smt(char *s)
 105 {
 106         get_option(&s, &smp_max_threads);
 107         return 0;
 108 }
 109 early_param("smt", early_smt);
 110
 111 /*
 112  * The smp_cpu_state_mutex must be held when changing the state or polarization
 113  * member of a pcpu data structure within the pcpu_devices arreay.
 114  */
 115 DEFINE_MUTEX(smp_cpu_state_mutex);
 116
 117 /*
 118  * Signal processor helper functions.
 119  */
 120 static inline int __pcpu_sigp_relax(u16 addr, u8 order, unsigned long parm)
 121 {
 122         int cc;
 123
 124         while (1) {
 125                 cc = __pcpu_sigp(addr, order, parm, NULL);
 126                 if (cc != SIGP_CC_BUSY)
 127                         return cc;
 128                 cpu_relax();
 129         }
 130 }
 131
 132 static int pcpu_sigp_retry(struct pcpu *pcpu, u8 order, u32 parm)
 133 {
 134         int cc, retry;
 135
 136         for (retry = 0; ; retry++) {
 137                 cc = __pcpu_sigp(pcpu->address, order, parm, NULL);
 138                 if (cc != SIGP_CC_BUSY)
 139                         break;
 140                 if (retry >= 3)
 141                         udelay(10);
 142         }
 143         return cc;
 144 }
 145
 146 static inline int pcpu_stopped(struct pcpu *pcpu)
 147 {
 148         u32 status;
 149
 150         if (__pcpu_sigp(pcpu->address, SIGP_SENSE,
 151                         0, &status) != SIGP_CC_STATUS_STORED)
 152                 return 0;
 153         return !!(status & (SIGP_STATUS_CHECK_STOP|SIGP_STATUS_STOPPED));
 154 }
 155
 156 static inline int pcpu_running(struct pcpu *pcpu)
 157 {
 158         if (__pcpu_sigp(pcpu->address, SIGP_SENSE_RUNNING,
 159                         0, NULL) != SIGP_CC_STATUS_STORED)
 160                 return 1;
 161         /* Status stored condition code is equivalent to cpu not running. */
 162         return 0;
 163 }
 164
 165 /*
 166  * Find struct pcpu by cpu address.
 167  */
 168 static struct pcpu *pcpu_find_address(const struct cpumask *mask, u16 address)
 169 {
 170         int cpu;
 171
 172         for_each_cpu(cpu, mask)
 173                 if (pcpu_devices[cpu].address == address)
 174                         return pcpu_devices + cpu;
 175         return NULL;
 176 }
 177
 178 static void pcpu_ec_call(struct pcpu *pcpu, int ec_bit)
 179 {
 180         int order;
 181
 182         if (test_and_set_bit(ec_bit, &pcpu->ec_mask))
 183                 return;
 184         order = pcpu_running(pcpu) ? SIGP_EXTERNAL_CALL : SIGP_EMERGENCY_SIGNAL;
 185         pcpu->ec_clk = get_tod_clock_fast();
 186         pcpu_sigp_retry(pcpu, order, 0);
 187 }
 188
 189 static int pcpu_alloc_lowcore(struct pcpu *pcpu, int cpu)
 190 {
 191         unsigned long async_stack, nodat_stack;
 192         struct lowcore *lc;
 193
 194         if (pcpu != &pcpu_devices[0]) {
 195                 pcpu->lowcore = (struct lowcore *)
 196                         __get_free_pages(GFP_KERNEL | GFP_DMA, LC_ORDER);
 197                 nodat_stack = __get_free_pages(GFP_KERNEL, THREAD_SIZE_ORDER);
 198                 if (!pcpu->lowcore || !nodat_stack)
 199                         goto out;
 200         } else {
 201                 nodat_stack = pcpu->lowcore->nodat_stack - STACK_INIT_OFFSET;
 202         }
 203         async_stack = stack_alloc();
 204         if (!async_stack)
 205                 goto out;
 206         lc = pcpu->lowcore;
 207         memcpy(lc, &S390_lowcore, 512);
 208         memset((char *) lc + 512, 0, sizeof(*lc) - 512);
 209         lc->async_stack = async_stack + STACK_INIT_OFFSET;
 210         lc->nodat_stack = nodat_stack + STACK_INIT_OFFSET;
 211         lc->cpu_nr = cpu;
 212         lc->spinlock_lockval = arch_spin_lockval(cpu);
 213         lc->spinlock_index = 0;
 214         lc->br_r1_trampoline = 0x07f1;  /* br %r1 */
 215         lc->return_lpswe = gen_lpswe(__LC_RETURN_PSW);
 216         lc->return_mcck_lpswe = gen_lpswe(__LC_RETURN_MCCK_PSW);
 217         if (nmi_alloc_per_cpu(lc))
 218                 goto out_async;
 219         if (vdso_alloc_per_cpu(lc))
 220                 goto out_mcesa;
 221         lowcore_ptr[cpu] = lc;
 222         pcpu_sigp_retry(pcpu, SIGP_SET_PREFIX, (u32)(unsigned long) lc);
 223         return 0;
 224
 225 out_mcesa:
 226         nmi_free_per_cpu(lc);
 227 out_async:
 228         stack_free(async_stack);
 229 out:
 230         if (pcpu != &pcpu_devices[0]) {
 231                 free_pages(nodat_stack, THREAD_SIZE_ORDER);
 232                 free_pages((unsigned long) pcpu->lowcore, LC_ORDER);
 233         }
 234         return -ENOMEM;
 235 }
 236
 237 static void pcpu_free_lowcore(struct pcpu *pcpu)
 238 {
 239         unsigned long async_stack, nodat_stack, lowcore;
 240
 241         nodat_stack = pcpu->lowcore->nodat_stack - STACK_INIT_OFFSET;
 242         async_stack = pcpu->lowcore->async_stack - STACK_INIT_OFFSET;
 243         lowcore = (unsigned long) pcpu->lowcore;
 244
 245         pcpu_sigp_retry(pcpu, SIGP_SET_PREFIX, 0);
 246         lowcore_ptr[pcpu - pcpu_devices] = NULL;
 247         vdso_free_per_cpu(pcpu->lowcore);
 248         nmi_free_per_cpu(pcpu->lowcore);
 249         stack_free(async_stack);
 250         if (pcpu == &pcpu_devices[0])
 251                 return;
 252         free_pages(nodat_stack, THREAD_SIZE_ORDER);
 253         free_pages(lowcore, LC_ORDER);
 254 }
 255
 256 static void pcpu_prepare_secondary(struct pcpu *pcpu, int cpu)
 257 {
 258         struct lowcore *lc = pcpu->lowcore;
 259
 260         cpumask_set_cpu(cpu, &init_mm.context.cpu_attach_mask);
 261         cpumask_set_cpu(cpu, mm_cpumask(&init_mm));
 262         lc->cpu_nr = cpu;
 263         lc->spinlock_lockval = arch_spin_lockval(cpu);
 264         lc->spinlock_index = 0;
 265         lc->percpu_offset = __per_cpu_offset[cpu];
 266         lc->kernel_asce = S390_lowcore.kernel_asce;
 267         lc->user_asce = S390_lowcore.kernel_asce;
 268         lc->machine_flags = S390_lowcore.machine_flags;
 269         lc->user_timer = lc->system_timer =
 270                 lc->steal_timer = lc->avg_steal_timer = 0;
 271         __ctl_store(lc->cregs_save_area, 0, 15);
 272         lc->cregs_save_area[1] = lc->kernel_asce;
 273         lc->cregs_save_area[7] = lc->vdso_asce;
 274         save_access_regs((unsigned int *) lc->access_regs_save_area);
 275         memcpy(lc->stfle_fac_list, S390_lowcore.stfle_fac_list,
 276                sizeof(lc->stfle_fac_list));
 277         memcpy(lc->alt_stfle_fac_list, S390_lowcore.alt_stfle_fac_list,
 278                sizeof(lc->alt_stfle_fac_list));
 279         arch_spin_lock_setup(cpu);
 280 }
 281
 282 static void pcpu_attach_task(struct pcpu *pcpu, struct task_struct *tsk)
 283 {
 284         struct lowcore *lc = pcpu->lowcore;
 285
 286         lc->kernel_stack = (unsigned long) task_stack_page(tsk)
 287                 + THREAD_SIZE - STACK_FRAME_OVERHEAD - sizeof(struct pt_regs);
 288         lc->current_task = (unsigned long) tsk;
 289         lc->lpp = LPP_MAGIC;
 290         lc->current_pid = tsk->pid;
 291         lc->user_timer = tsk->thread.user_timer;
 292         lc->guest_timer = tsk->thread.guest_timer;
 293         lc->system_timer = tsk->thread.system_timer;
 294         lc->hardirq_timer = tsk->thread.hardirq_timer;
 295         lc->softirq_timer = tsk->thread.softirq_timer;
 296         lc->steal_timer = 0;
 297 }
 298
 299 static void pcpu_start_fn(struct pcpu *pcpu, void (*func)(void *), void *data)
 300 {
 301         struct lowcore *lc = pcpu->lowcore;
 302
 303         lc->restart_stack = lc->nodat_stack;
 304         lc->restart_fn = (unsigned long) func;
 305         lc->restart_data = (unsigned long) data;
 306         lc->restart_source = -1UL;
 307         pcpu_sigp_retry(pcpu, SIGP_RESTART, 0);
 308 }
 309
 310 /*
 311  * Call function via PSW restart on pcpu and stop the current cpu.
 312  */
 313 static void __pcpu_delegate(void (*func)(void*), void *data)
 314 {
 315         func(data);     /* should not return */
 316 }
 317
 318 static void __no_sanitize_address pcpu_delegate(struct pcpu *pcpu,
 319                                                 void (*func)(void *),
 320                                                 void *data, unsigned long stack)
 321 {
 322         struct lowcore *lc = lowcore_ptr[pcpu - pcpu_devices];
 323         unsigned long source_cpu = stap();
 324
 325         __load_psw_mask(PSW_KERNEL_BITS | PSW_MASK_DAT);
 326         if (pcpu->address == source_cpu)
 327                 CALL_ON_STACK(__pcpu_delegate, stack, 2, func, data);
 328         /* Stop target cpu (if func returns this stops the current cpu). */
 329         pcpu_sigp_retry(pcpu, SIGP_STOP, 0);
 330         /* Restart func on the target cpu and stop the current cpu. */
 331         mem_assign_absolute(lc->restart_stack, stack);
 332         mem_assign_absolute(lc->restart_fn, (unsigned long) func);
 333         mem_assign_absolute(lc->restart_data, (unsigned long) data);
 334         mem_assign_absolute(lc->restart_source, source_cpu);
 335         __bpon();
 336         asm volatile(
 337                 "0:     sigp    0,%0,%2 # sigp restart to target cpu\n"
 338                 "       brc     2,0b    # busy, try again\n"
 339                 "1:     sigp    0,%1,%3 # sigp stop to current cpu\n"
 340                 "       brc     2,1b    # busy, try again\n"
 341                 : : "d" (pcpu->address), "d" (source_cpu),
 342                     "K" (SIGP_RESTART), "K" (SIGP_STOP)
 343                 : "0", "1", "cc");
 344         for (;;) ;
 345 }
 346
 347 /*
 348  * Enable additional logical cpus for multi-threading.
 349  */
 350 static int pcpu_set_smt(unsigned int mtid)
 351 {
 352         int cc;
 353
 354         if (smp_cpu_mtid == mtid)
 355                 return 0;
 356         cc = __pcpu_sigp(0, SIGP_SET_MULTI_THREADING, mtid, NULL);
 357         if (cc == 0) {
 358                 smp_cpu_mtid = mtid;
 359                 smp_cpu_mt_shift = 0;
 360                 while (smp_cpu_mtid >= (1U << smp_cpu_mt_shift))
 361                         smp_cpu_mt_shift++;
 362                 pcpu_devices[0].address = stap();
 363         }
 364         return cc;
 365 }
 366
 367 /*
 368  * Call function on an online CPU.
 369  */
 370 void smp_call_online_cpu(void (*func)(void *), void *data)
 371 {
 372         struct pcpu *pcpu;
 373
 374         /* Use the current cpu if it is online. */
 375         pcpu = pcpu_find_address(cpu_online_mask, stap());
 376         if (!pcpu)
 377                 /* Use the first online cpu. */
 378                 pcpu = pcpu_devices + cpumask_first(cpu_online_mask);
 379         pcpu_delegate(pcpu, func, data, (unsigned long) restart_stack);
 380 }
 381
 382 /*
 383  * Call function on the ipl CPU.
 384  */
 385 void smp_call_ipl_cpu(void (*func)(void *), void *data)
 386 {
 387         struct lowcore *lc = pcpu_devices->lowcore;
 388
 389         if (pcpu_devices[0].address == stap())
 390                 lc = &S390_lowcore;
 391
 392         pcpu_delegate(&pcpu_devices[0], func, data,
 393                       lc->nodat_stack);
 394 }
 395
 396 int smp_find_processor_id(u16 address)
 397 {
 398         int cpu;
 399
 400         for_each_present_cpu(cpu)
 401                 if (pcpu_devices[cpu].address == address)
 402                         return cpu;
 403         return -1;
 404 }
 405
 406 bool notrace arch_vcpu_is_preempted(int cpu)
 407 {
 408         if (test_cpu_flag_of(CIF_ENABLED_WAIT, cpu))
 409                 return false;
 410         if (pcpu_running(pcpu_devices + cpu))
 411                 return false;
 412         return true;
 413 }
 414 EXPORT_SYMBOL(arch_vcpu_is_preempted);
 415
 416 void notrace smp_yield_cpu(int cpu)
 417 {
 418         if (MACHINE_HAS_DIAG9C) {
 419                 diag_stat_inc_norecursion(DIAG_STAT_X09C);
 420                 asm volatile("diag %0,0,0x9c"
 421                              : : "d" (pcpu_devices[cpu].address));
 422         } else if (MACHINE_HAS_DIAG44 && !smp_cpu_mtid) {
 423                 diag_stat_inc_norecursion(DIAG_STAT_X044);
 424                 asm volatile("diag 0,0,0x44");
 425         }
 426 }
 427
 428 /*
 429  * Send cpus emergency shutdown signal. This gives the cpus the
 430  * opportunity to complete outstanding interrupts.
 431  */
 432 void notrace smp_emergency_stop(void)
 433 {
 434         cpumask_t cpumask;
 435         u64 end;
 436         int cpu;
 437
 438         cpumask_copy(&cpumask, cpu_online_mask);
 439         cpumask_clear_cpu(smp_processor_id(), &cpumask);
 440
 441         end = get_tod_clock() + (1000000UL << 12);
 442         for_each_cpu(cpu, &cpumask) {
 443                 struct pcpu *pcpu = pcpu_devices + cpu;
 444                 set_bit(ec_stop_cpu, &pcpu->ec_mask);
 445                 while (__pcpu_sigp(pcpu->address, SIGP_EMERGENCY_SIGNAL,
 446                                    0, NULL) == SIGP_CC_BUSY &&
 447                        get_tod_clock() < end)
 448                         cpu_relax();
 449         }
 450         while (get_tod_clock() < end) {
 451                 for_each_cpu(cpu, &cpumask)
 452                         if (pcpu_stopped(pcpu_devices + cpu))
 453                                 cpumask_clear_cpu(cpu, &cpumask);
 454                 if (cpumask_empty(&cpumask))
 455                         break;
 456                 cpu_relax();
 457         }
 458 }
 459 NOKPROBE_SYMBOL(smp_emergency_stop);
 460
 461 /*
 462  * Stop all cpus but the current one.
 463  */
 464 void smp_send_stop(void)
 465 {
 466         int cpu;
 467
 468         /* Disable all interrupts/machine checks */
 469         __load_psw_mask(PSW_KERNEL_BITS | PSW_MASK_DAT);
 470         trace_hardirqs_off();
 471
 472         debug_set_critical();
 473
 474         if (oops_in_progress)
 475                 smp_emergency_stop();
 476
 477         /* stop all processors */
 478         for_each_online_cpu(cpu) {
 479                 if (cpu == smp_processor_id())
 480                         continue;
 481                 pcpu_sigp_retry(pcpu_devices + cpu, SIGP_STOP, 0);
 482                 while (!pcpu_stopped(pcpu_devices + cpu))
 483                         cpu_relax();
 484         }
 485 }
 486
 487 /*
 488  * This is the main routine where commands issued by other
 489  * cpus are handled.
 490  */
 491 static void smp_handle_ext_call(void)
 492 {
 493         unsigned long bits;
 494
 495         /* handle bit signal external calls */
 496         bits = xchg(&pcpu_devices[smp_processor_id()].ec_mask, 0);
 497         if (test_bit(ec_stop_cpu, &bits))
 498                 smp_stop_cpu();
 499         if (test_bit(ec_schedule, &bits))
 500                 scheduler_ipi();
 501         if (test_bit(ec_call_function_single, &bits))
 502                 generic_smp_call_function_single_interrupt();
 503 }
 504
 505 static void do_ext_call_interrupt(struct ext_code ext_code,
 506                                   unsigned int param32, unsigned long param64)
 507 {
 508         inc_irq_stat(ext_code.code == 0x1202 ? IRQEXT_EXC : IRQEXT_EMS);
 509         smp_handle_ext_call();
 510 }
 511
 512 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
 513 {
 514         int cpu;
 515
 516         for_each_cpu(cpu, mask)
 517                 pcpu_ec_call(pcpu_devices + cpu, ec_call_function_single);
 518 }
 519
 520 void arch_send_call_function_single_ipi(int cpu)
 521 {
 522         pcpu_ec_call(pcpu_devices + cpu, ec_call_function_single);
 523 }
 524
 525 /*
 526  * this function sends a 'reschedule' IPI to another CPU.
 527  * it goes straight through and wastes no time serializing
 528  * anything. Worst case is that we lose a reschedule ...
 529  */
 530 void smp_send_reschedule(int cpu)
 531 {
 532         pcpu_ec_call(pcpu_devices + cpu, ec_schedule);
 533 }
 534
 535 /*
 536  * parameter area for the set/clear control bit callbacks
 537  */
 538 struct ec_creg_mask_parms {
 539         unsigned long orval;
 540         unsigned long andval;
 541         int cr;
 542 };
 543
 544 /*
 545  * callback for setting/clearing control bits
 546  */
 547 static void smp_ctl_bit_callback(void *info)
 548 {
 549         struct ec_creg_mask_parms *pp = info;
 550         unsigned long cregs[16];
 551
 552         __ctl_store(cregs, 0, 15);
 553         cregs[pp->cr] = (cregs[pp->cr] & pp->andval) | pp->orval;
 554         __ctl_load(cregs, 0, 15);
 555 }
 556
 557 /*
 558  * Set a bit in a control register of all cpus
 559  */
 560 void smp_ctl_set_bit(int cr, int bit)
 561 {
 562         struct ec_creg_mask_parms parms = { 1UL << bit, -1UL, cr };
 563
 564         on_each_cpu(smp_ctl_bit_callback, &parms, 1);
 565 }
 566 EXPORT_SYMBOL(smp_ctl_set_bit);
 567
 568 /*
 569  * Clear a bit in a control register of all cpus
 570  */
 571 void smp_ctl_clear_bit(int cr, int bit)
 572 {
 573         struct ec_creg_mask_parms parms = { 0, ~(1UL << bit), cr };
 574
 575         on_each_cpu(smp_ctl_bit_callback, &parms, 1);
 576 }
 577 EXPORT_SYMBOL(smp_ctl_clear_bit);
 578
 579 #ifdef CONFIG_CRASH_DUMP
 580
 581 int smp_store_status(int cpu)
 582 {
 583         struct pcpu *pcpu = pcpu_devices + cpu;
 584         unsigned long pa;
 585
 586         pa = __pa(&pcpu->lowcore->floating_pt_save_area);
 587         if (__pcpu_sigp_relax(pcpu->address, SIGP_STORE_STATUS_AT_ADDRESS,
 588                               pa) != SIGP_CC_ORDER_CODE_ACCEPTED)
 589                 return -EIO;
 590         if (!MACHINE_HAS_VX && !MACHINE_HAS_GS)
 591                 return 0;
 592         pa = __pa(pcpu->lowcore->mcesad & MCESA_ORIGIN_MASK);
 593         if (MACHINE_HAS_GS)
 594                 pa |= pcpu->lowcore->mcesad & MCESA_LC_MASK;
 595         if (__pcpu_sigp_relax(pcpu->address, SIGP_STORE_ADDITIONAL_STATUS,
 596                               pa) != SIGP_CC_ORDER_CODE_ACCEPTED)
 597                 return -EIO;
 598         return 0;
 599 }
 600
 601 /*
 602  * Collect CPU state of the previous, crashed system.
 603  * There are four cases:
 604  * 1) standard zfcp dump
 605  *    condition: OLDMEM_BASE == NULL && ipl_info.type == IPL_TYPE_FCP_DUMP
 606  *    The state for all CPUs except the boot CPU needs to be collected
 607  *    with sigp stop-and-store-status. The boot CPU state is located in
 608  *    the absolute lowcore of the memory stored in the HSA. The zcore code
 609  *    will copy the boot CPU state from the HSA.
 610  * 2) stand-alone kdump for SCSI (zfcp dump with swapped memory)
 611  *    condition: OLDMEM_BASE != NULL && ipl_info.type == IPL_TYPE_FCP_DUMP
 612  *    The state for all CPUs except the boot CPU needs to be collected
 613  *    with sigp stop-and-store-status. The firmware or the boot-loader
 614  *    stored the registers of the boot CPU in the absolute lowcore in the
 615  *    memory of the old system.
 616  * 3) kdump and the old kernel did not store the CPU state,
 617  *    or stand-alone kdump for DASD
 618  *    condition: OLDMEM_BASE != NULL && !is_kdump_kernel()
 619  *    The state for all CPUs except the boot CPU needs to be collected
 620  *    with sigp stop-and-store-status. The kexec code or the boot-loader
 621  *    stored the registers of the boot CPU in the memory of the old system.
 622  * 4) kdump and the old kernel stored the CPU state
 623  *    condition: OLDMEM_BASE != NULL && is_kdump_kernel()
 624  *    This case does not exist for s390 anymore, setup_arch explicitly
 625  *    deactivates the elfcorehdr= kernel parameter
 626  */
 627 static __init void smp_save_cpu_vxrs(struct save_area *sa, u16 addr,
 628                                      bool is_boot_cpu, unsigned long page)
 629 {
 630         __vector128 *vxrs = (__vector128 *) page;
 631
 632         if (is_boot_cpu)
 633                 vxrs = boot_cpu_vector_save_area;
 634         else
 635                 __pcpu_sigp_relax(addr, SIGP_STORE_ADDITIONAL_STATUS, page);
 636         save_area_add_vxrs(sa, vxrs);
 637 }
 638
 639 static __init void smp_save_cpu_regs(struct save_area *sa, u16 addr,
 640                                      bool is_boot_cpu, unsigned long page)
 641 {
 642         void *regs = (void *) page;
 643
 644         if (is_boot_cpu)
 645                 copy_oldmem_kernel(regs, (void *) __LC_FPREGS_SAVE_AREA, 512);
 646         else
 647                 __pcpu_sigp_relax(addr, SIGP_STORE_STATUS_AT_ADDRESS, page);
 648         save_area_add_regs(sa, regs);
 649 }
 650
 651 void __init smp_save_dump_cpus(void)
 652 {
 653         int addr, boot_cpu_addr, max_cpu_addr;
 654         struct save_area *sa;
 655         unsigned long page;
 656         bool is_boot_cpu;
 657
 658         if (!(OLDMEM_BASE || ipl_info.type == IPL_TYPE_FCP_DUMP))
 659                 /* No previous system present, normal boot. */
 660                 return;
 661         /* Allocate a page as dumping area for the store status sigps */
 662         page = memblock_phys_alloc_range(PAGE_SIZE, PAGE_SIZE, 0, 1UL << 31);
 663         if (!page)
 664                 panic("ERROR: Failed to allocate %lx bytes below %lx\n",
 665                       PAGE_SIZE, 1UL << 31);
 666
 667         /* Set multi-threading state to the previous system. */
 668         pcpu_set_smt(sclp.mtid_prev);
 669         boot_cpu_addr = stap();
 670         max_cpu_addr = SCLP_MAX_CORES << sclp.mtid_prev;
 671         for (addr = 0; addr <= max_cpu_addr; addr++) {
 672                 if (__pcpu_sigp_relax(addr, SIGP_SENSE, 0) ==
 673                     SIGP_CC_NOT_OPERATIONAL)
 674                         continue;
 675                 is_boot_cpu = (addr == boot_cpu_addr);
 676                 /* Allocate save area */
 677                 sa = save_area_alloc(is_boot_cpu);
 678                 if (!sa)
 679                         panic("could not allocate memory for save area\n");
 680                 if (MACHINE_HAS_VX)
 681                         /* Get the vector registers */
 682                         smp_save_cpu_vxrs(sa, addr, is_boot_cpu, page);
 683                 /*
 684                  * For a zfcp dump OLDMEM_BASE == NULL and the registers
 685                  * of the boot CPU are stored in the HSA. To retrieve
 686                  * these registers an SCLP request is required which is
 687                  * done by drivers/s390/char/zcore.c:init_cpu_info()
 688                  */
 689                 if (!is_boot_cpu || OLDMEM_BASE)
 690                         /* Get the CPU registers */
 691                         smp_save_cpu_regs(sa, addr, is_boot_cpu, page);
 692         }
 693         memblock_free(page, PAGE_SIZE);
 694         diag_dma_ops.diag308_reset();
 695         pcpu_set_smt(0);
 696 }
 697 #endif /* CONFIG_CRASH_DUMP */
 698
 699 void smp_cpu_set_polarization(int cpu, int val)
 700 {
 701         pcpu_devices[cpu].polarization = val;
 702 }
 703
 704 int smp_cpu_get_polarization(int cpu)
 705 {
 706         return pcpu_devices[cpu].polarization;
 707 }
 708
 709 static void __ref smp_get_core_info(struct sclp_core_info *info, int early)
 710 {
 711         static int use_sigp_detection;
 712         int address;
 713
 714         if (use_sigp_detection || sclp_get_core_info(info, early)) {
 715                 use_sigp_detection = 1;
 716                 for (address = 0;
 717                      address < (SCLP_MAX_CORES << smp_cpu_mt_shift);
 718                      address += (1U << smp_cpu_mt_shift)) {
 719                         if (__pcpu_sigp_relax(address, SIGP_SENSE, 0) ==
 720                             SIGP_CC_NOT_OPERATIONAL)
 721                                 continue;
 722                         info->core[info->configured].core_id =
 723                                 address >> smp_cpu_mt_shift;
 724                         info->configured++;
 725                 }
 726                 info->combined = info->configured;
 727         }
 728 }
 729
 730 static int smp_add_present_cpu(int cpu);
 731
 732 static int smp_add_core(struct sclp_core_entry *core, cpumask_t *avail,
 733                         bool configured, bool early)
 734 {
 735         struct pcpu *pcpu;
 736         int cpu, nr, i;
 737         u16 address;
 738
 739         nr = 0;
 740         if (sclp.has_core_type && core->type != boot_core_type)
 741                 return nr;
 742         cpu = cpumask_first(avail);
 743         address = core->core_id << smp_cpu_mt_shift;
 744         for (i = 0; (i <= smp_cpu_mtid) && (cpu < nr_cpu_ids); i++) {
 745                 if (pcpu_find_address(cpu_present_mask, address + i))
 746                         continue;
 747                 pcpu = pcpu_devices + cpu;
 748                 pcpu->address = address + i;
 749                 if (configured)
 750                         pcpu->state = CPU_STATE_CONFIGURED;
 751                 else
 752                         pcpu->state = CPU_STATE_STANDBY;
 753                 smp_cpu_set_polarization(cpu, POLARIZATION_UNKNOWN);
 754                 set_cpu_present(cpu, true);
 755                 if (!early && smp_add_present_cpu(cpu) != 0)
 756                         set_cpu_present(cpu, false);
 757                 else
 758                         nr++;
 759                 cpumask_clear_cpu(cpu, avail);
 760                 cpu = cpumask_next(cpu, avail);
 761         }
 762         return nr;
 763 }
 764
 765 static int __smp_rescan_cpus(struct sclp_core_info *info, bool early)
 766 {
 767         struct sclp_core_entry *core;
 768         static cpumask_t avail;
 769         bool configured;
 770         u16 core_id;
 771         int nr, i;
 772
 773         nr = 0;
 774         cpumask_xor(&avail, cpu_possible_mask, cpu_present_mask);
 775         /*
 776          * Add IPL core first (which got logical CPU number 0) to make sure
 777          * that all SMT threads get subsequent logical CPU numbers.
 778          */
 779         if (early) {
 780                 core_id = pcpu_devices[0].address >> smp_cpu_mt_shift;
 781                 for (i = 0; i < info->configured; i++) {
 782                         core = &info->core[i];
 783                         if (core->core_id == core_id) {
 784                                 nr += smp_add_core(core, &avail, true, early);
 785                                 break;
 786                         }
 787                 }
 788         }
 789         for (i = 0; i < info->combined; i++) {
 790                 configured = i < info->configured;
 791                 nr += smp_add_core(&info->core[i], &avail, configured, early);
 792         }
 793         return nr;
 794 }
 795
 796 void __init smp_detect_cpus(void)
 797 {
 798         unsigned int cpu, mtid, c_cpus, s_cpus;
 799         struct sclp_core_info *info;
 800         u16 address;
 801
 802         /* Get CPU information */
 803         info = memblock_alloc(sizeof(*info), 8);
 804         if (!info)
 805                 panic("%s: Failed to allocate %zu bytes align=0x%x\n",
 806                       __func__, sizeof(*info), 8);
 807         smp_get_core_info(info, 1);
 808         /* Find boot CPU type */
 809         if (sclp.has_core_type) {
 810                 address = stap();
 811                 for (cpu = 0; cpu < info->combined; cpu++)
 812                         if (info->core[cpu].core_id == address) {
 813                                 /* The boot cpu dictates the cpu type. */
 814                                 boot_core_type = info->core[cpu].type;
 815                                 break;
 816                         }
 817                 if (cpu >= info->combined)
 818                         panic("Could not find boot CPU type");
 819         }
 820
 821         /* Set multi-threading state for the current system */
 822         mtid = boot_core_type ? sclp.mtid : sclp.mtid_cp;
 823         mtid = (mtid < smp_max_threads) ? mtid : smp_max_threads - 1;
 824         pcpu_set_smt(mtid);
 825
 826         /* Print number of CPUs */
 827         c_cpus = s_cpus = 0;
 828         for (cpu = 0; cpu < info->combined; cpu++) {
 829                 if (sclp.has_core_type &&
 830                     info->core[cpu].type != boot_core_type)
 831                         continue;
 832                 if (cpu < info->configured)
 833                         c_cpus += smp_cpu_mtid + 1;
 834                 else
 835                         s_cpus += smp_cpu_mtid + 1;
 836         }
 837         pr_info("%d configured CPUs, %d standby CPUs\n", c_cpus, s_cpus);
 838
 839         /* Add CPUs present at boot */
 840         get_online_cpus();
 841         __smp_rescan_cpus(info, true);
 842         put_online_cpus();
 843         memblock_free_early((unsigned long)info, sizeof(*info));
 844 }
 845
 846 static void smp_init_secondary(void)
 847 {
 848         int cpu = raw_smp_processor_id();
 849
 850         S390_lowcore.last_update_clock = get_tod_clock();
 851         restore_access_regs(S390_lowcore.access_regs_save_area);
 852         set_cpu_flag(CIF_ASCE_PRIMARY);
 853         set_cpu_flag(CIF_ASCE_SECONDARY);
 854         cpu_init();
 855         rcu_cpu_starting(cpu);
 856         preempt_disable();
 857         init_cpu_timer();
 858         vtime_init();
 859         pfault_init();
 860         notify_cpu_starting(smp_processor_id());
 861         if (topology_cpu_dedicated(cpu))
 862                 set_cpu_flag(CIF_DEDICATED_CPU);
 863         else
 864                 clear_cpu_flag(CIF_DEDICATED_CPU);
 865         set_cpu_online(smp_processor_id(), true);
 866         inc_irq_stat(CPU_RST);
 867         local_irq_enable();
 868         cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
 869 }
 870
 871 /*
 872  *      Activate a secondary processor.
 873  */
 874 static void __no_sanitize_address smp_start_secondary(void *cpuvoid)
 875 {
 876         S390_lowcore.restart_stack = (unsigned long) restart_stack;
 877         S390_lowcore.restart_fn = (unsigned long) do_restart;
 878         S390_lowcore.restart_data = 0;
 879         S390_lowcore.restart_source = -1UL;
 880         __ctl_load(S390_lowcore.cregs_save_area, 0, 15);
 881         __load_psw_mask(PSW_KERNEL_BITS | PSW_MASK_DAT);
 882         CALL_ON_STACK_NORETURN(smp_init_secondary, S390_lowcore.kernel_stack);
 883 }
 884
 885 /* Upping and downing of CPUs */
 886 int __cpu_up(unsigned int cpu, struct task_struct *tidle)
 887 {
 888         struct pcpu *pcpu = pcpu_devices + cpu;
 889         int rc;
 890
 891         if (pcpu->state != CPU_STATE_CONFIGURED)
 892                 return -EIO;
 893         if (pcpu_sigp_retry(pcpu, SIGP_INITIAL_CPU_RESET, 0) !=
 894             SIGP_CC_ORDER_CODE_ACCEPTED)
 895                 return -EIO;
 896
 897         rc = pcpu_alloc_lowcore(pcpu, cpu);
 898         if (rc)
 899                 return rc;
 900         pcpu_prepare_secondary(pcpu, cpu);
 901         pcpu_attach_task(pcpu, tidle);
 902         pcpu_start_fn(pcpu, smp_start_secondary, NULL);
 903         /* Wait until cpu puts itself in the online & active maps */
 904         while (!cpu_online(cpu))
 905                 cpu_relax();
 906         return 0;
 907 }
 908
 909 static unsigned int setup_possible_cpus __initdata;
 910
 911 static int __init _setup_possible_cpus(char *s)
 912 {
 913         get_option(&s, &setup_possible_cpus);
 914         return 0;
 915 }
 916 early_param("possible_cpus", _setup_possible_cpus);
 917
 918 int __cpu_disable(void)
 919 {
 920         unsigned long cregs[16];
 921
 922         /* Handle possible pending IPIs */
 923         smp_handle_ext_call();
 924         set_cpu_online(smp_processor_id(), false);
 925         /* Disable pseudo page faults on this cpu. */
 926         pfault_fini();
 927         /* Disable interrupt sources via control register. */
 928         __ctl_store(cregs, 0, 15);
 929         cregs[0]  &= ~0x0000ee70UL;     /* disable all external interrupts */
 930         cregs[6]  &= ~0xff000000UL;     /* disable all I/O interrupts */
 931         cregs[14] &= ~0x1f000000UL;     /* disable most machine checks */
 932         __ctl_load(cregs, 0, 15);
 933         clear_cpu_flag(CIF_NOHZ_DELAY);
 934         return 0;
 935 }
 936
 937 void __cpu_die(unsigned int cpu)
 938 {
 939         struct pcpu *pcpu;
 940
 941         /* Wait until target cpu is down */
 942         pcpu = pcpu_devices + cpu;
 943         while (!pcpu_stopped(pcpu))
 944                 cpu_relax();
 945         pcpu_free_lowcore(pcpu);
 946         cpumask_clear_cpu(cpu, mm_cpumask(&init_mm));
 947         cpumask_clear_cpu(cpu, &init_mm.context.cpu_attach_mask);
 948 }
 949
 950 void __noreturn cpu_die(void)
 951 {
 952         idle_task_exit();
 953         __bpon();
 954         pcpu_sigp_retry(pcpu_devices + smp_processor_id(), SIGP_STOP, 0);
 955         for (;;) ;
 956 }
 957
 958 void __init smp_fill_possible_mask(void)
 959 {
 960         unsigned int possible, sclp_max, cpu;
 961
 962         sclp_max = max(sclp.mtid, sclp.mtid_cp) + 1;
 963         sclp_max = min(smp_max_threads, sclp_max);
 964         sclp_max = (sclp.max_cores * sclp_max) ?: nr_cpu_ids;
 965         possible = setup_possible_cpus ?: nr_cpu_ids;
 966         possible = min(possible, sclp_max);
 967         for (cpu = 0; cpu < possible && cpu < nr_cpu_ids; cpu++)
 968                 set_cpu_possible(cpu, true);
 969 }
 970
 971 void __init smp_prepare_cpus(unsigned int max_cpus)
 972 {
 973         /* request the 0x1201 emergency signal external interrupt */
 974         if (register_external_irq(EXT_IRQ_EMERGENCY_SIG, do_ext_call_interrupt))
 975                 panic("Couldn't request external interrupt 0x1201");
 976         /* request the 0x1202 external call external interrupt */
 977         if (register_external_irq(EXT_IRQ_EXTERNAL_CALL, do_ext_call_interrupt))
 978                 panic("Couldn't request external interrupt 0x1202");
 979 }
 980
 981 void __init smp_prepare_boot_cpu(void)
 982 {
 983         struct pcpu *pcpu = pcpu_devices;
 984
 985         WARN_ON(!cpu_present(0) || !cpu_online(0));
 986         pcpu->state = CPU_STATE_CONFIGURED;
 987         pcpu->lowcore = (struct lowcore *)(unsigned long) store_prefix();
 988         S390_lowcore.percpu_offset = __per_cpu_offset[0];
 989         smp_cpu_set_polarization(0, POLARIZATION_UNKNOWN);
 990 }
 991
 992 void __init smp_cpus_done(unsigned int max_cpus)
 993 {
 994 }
 995
 996 void __init smp_setup_processor_id(void)
 997 {
 998         pcpu_devices[0].address = stap();
 999         S390_lowcore.cpu_nr = 0;
1000         S390_lowcore.spinlock_lockval = arch_spin_lockval(0);
1001         S390_lowcore.spinlock_index = 0;
1002 }
1003
1004 /*
1005  * the frequency of the profiling timer can be changed
1006  * by writing a multiplier value into /proc/profile.
1007  *
1008  * usually you want to run this on all CPUs ;)
1009  */
1010 int setup_profiling_timer(unsigned int multiplier)
1011 {
1012         return 0;
1013 }
1014
1015 static ssize_t cpu_configure_show(struct device *dev,
1016                                   struct device_attribute *attr, char *buf)
1017 {
1018         ssize_t count;
1019
1020         mutex_lock(&smp_cpu_state_mutex);
1021         count = sprintf(buf, "%d\n", pcpu_devices[dev->id].state);
1022         mutex_unlock(&smp_cpu_state_mutex);
1023         return count;
1024 }
1025
1026 static ssize_t cpu_configure_store(struct device *dev,
1027                                    struct device_attribute *attr,
1028                                    const char *buf, size_t count)
1029 {
1030         struct pcpu *pcpu;
1031         int cpu, val, rc, i;
1032         char delim;
1033
1034         if (sscanf(buf, "%d %c", &val, &delim) != 1)
1035                 return -EINVAL;
1036         if (val != 0 && val != 1)
1037                 return -EINVAL;
1038         get_online_cpus();
1039         mutex_lock(&smp_cpu_state_mutex);
1040         rc = -EBUSY;
1041         /* disallow configuration changes of online cpus and cpu 0 */
1042         cpu = dev->id;
1043         cpu = smp_get_base_cpu(cpu);
1044         if (cpu == 0)
1045                 goto out;
1046         for (i = 0; i <= smp_cpu_mtid; i++)
1047                 if (cpu_online(cpu + i))
1048                         goto out;
1049         pcpu = pcpu_devices + cpu;
1050         rc = 0;
1051         switch (val) {
1052         case 0:
1053                 if (pcpu->state != CPU_STATE_CONFIGURED)
1054                         break;
1055                 rc = sclp_core_deconfigure(pcpu->address >> smp_cpu_mt_shift);
1056                 if (rc)
1057                         break;
1058                 for (i = 0; i <= smp_cpu_mtid; i++) {
1059                         if (cpu + i >= nr_cpu_ids || !cpu_present(cpu + i))
1060                                 continue;
1061                         pcpu[i].state = CPU_STATE_STANDBY;
1062                         smp_cpu_set_polarization(cpu + i,
1063                                                  POLARIZATION_UNKNOWN);
1064                 }
1065                 topology_expect_change();
1066                 break;
1067         case 1:
1068                 if (pcpu->state != CPU_STATE_STANDBY)
1069                         break;
1070                 rc = sclp_core_configure(pcpu->address >> smp_cpu_mt_shift);
1071                 if (rc)
1072                         break;
1073                 for (i = 0; i <= smp_cpu_mtid; i++) {
1074                         if (cpu + i >= nr_cpu_ids || !cpu_present(cpu + i))
1075                                 continue;
1076                         pcpu[i].state = CPU_STATE_CONFIGURED;
1077                         smp_cpu_set_polarization(cpu + i,
1078                                                  POLARIZATION_UNKNOWN);
1079                 }
1080                 topology_expect_change();
1081                 break;
1082         default:
1083                 break;
1084         }
1085 out:
1086         mutex_unlock(&smp_cpu_state_mutex);
1087         put_online_cpus();
1088         return rc ? rc : count;
1089 }
1090 static DEVICE_ATTR(configure, 0644, cpu_configure_show, cpu_configure_store);
1091
1092 static ssize_t show_cpu_address(struct device *dev,
1093                                 struct device_attribute *attr, char *buf)
1094 {
1095         return sprintf(buf, "%d\n", pcpu_devices[dev->id].address);
1096 }
1097 static DEVICE_ATTR(address, 0444, show_cpu_address, NULL);
1098
1099 static struct attribute *cpu_common_attrs[] = {
1100         &dev_attr_configure.attr,
1101         &dev_attr_address.attr,
1102         NULL,
1103 };
1104
1105 static struct attribute_group cpu_common_attr_group = {
1106         .attrs = cpu_common_attrs,
1107 };
1108
1109 static struct attribute *cpu_online_attrs[] = {
1110         &dev_attr_idle_count.attr,
1111         &dev_attr_idle_time_us.attr,
1112         NULL,
1113 };
1114
1115 static struct attribute_group cpu_online_attr_group = {
1116         .attrs = cpu_online_attrs,
1117 };
1118
1119 static int smp_cpu_online(unsigned int cpu)
1120 {
1121         struct device *s = &per_cpu(cpu_device, cpu)->dev;
1122
1123         return sysfs_create_group(&s->kobj, &cpu_online_attr_group);
1124 }
1125 static int smp_cpu_pre_down(unsigned int cpu)
1126 {
1127         struct device *s = &per_cpu(cpu_device, cpu)->dev;
1128
1129         sysfs_remove_group(&s->kobj, &cpu_online_attr_group);
1130         return 0;
1131 }
1132
1133 static int smp_add_present_cpu(int cpu)
1134 {
1135         struct device *s;
1136         struct cpu *c;
1137         int rc;
1138
1139         c = kzalloc(sizeof(*c), GFP_KERNEL);
1140         if (!c)
1141                 return -ENOMEM;
1142         per_cpu(cpu_device, cpu) = c;
1143         s = &c->dev;
1144         c->hotpluggable = 1;
1145         rc = register_cpu(c, cpu);
1146         if (rc)
1147                 goto out;
1148         rc = sysfs_create_group(&s->kobj, &cpu_common_attr_group);
1149         if (rc)
1150                 goto out_cpu;
1151         rc = topology_cpu_init(c);
1152         if (rc)
1153                 goto out_topology;
1154         return 0;
1155
1156 out_topology:
1157         sysfs_remove_group(&s->kobj, &cpu_common_attr_group);
1158 out_cpu:
1159         unregister_cpu(c);
1160 out:
1161         return rc;
1162 }
1163
1164 int __ref smp_rescan_cpus(void)
1165 {
1166         struct sclp_core_info *info;
1167         int nr;
1168
1169         info = kzalloc(sizeof(*info), GFP_KERNEL);
1170         if (!info)
1171                 return -ENOMEM;
1172         smp_get_core_info(info, 0);
1173         get_online_cpus();
1174         mutex_lock(&smp_cpu_state_mutex);
1175         nr = __smp_rescan_cpus(info, false);
1176         mutex_unlock(&smp_cpu_state_mutex);
1177         put_online_cpus();
1178         kfree(info);
1179         if (nr)
1180                 topology_schedule_update();
1181         return 0;
1182 }
1183
1184 static ssize_t __ref rescan_store(struct device *dev,
1185                                   struct device_attribute *attr,
1186                                   const char *buf,
1187                                   size_t count)
1188 {
1189         int rc;
1190
1191         rc = lock_device_hotplug_sysfs();
1192         if (rc)
1193                 return rc;
1194         rc = smp_rescan_cpus();
1195         unlock_device_hotplug();
1196         return rc ? rc : count;
1197 }
1198 static DEVICE_ATTR_WO(rescan);
1199
1200 static int __init s390_smp_init(void)
1201 {
1202         int cpu, rc = 0;
1203
1204         rc = device_create_file(cpu_subsys.dev_root, &dev_attr_rescan);
1205         if (rc)
1206                 return rc;
1207         for_each_present_cpu(cpu) {
1208                 rc = smp_add_present_cpu(cpu);
1209                 if (rc)
1210                         goto out;
1211         }
1212
1213         rc = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "s390/smp:online",
1214                                smp_cpu_online, smp_cpu_pre_down);
1215         rc = rc <= 0 ? rc : 0;
1216 out:
1217         return rc;
1218 }
1219 subsys_initcall(s390_smp_init);