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 uninitialized_var(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         if (nmi_alloc_per_cpu(lc))
 216                 goto out_async;
 217         if (vdso_alloc_per_cpu(lc))
 218                 goto out_mcesa;
 219         lowcore_ptr[cpu] = lc;
 220         pcpu_sigp_retry(pcpu, SIGP_SET_PREFIX, (u32)(unsigned long) lc);
 221         return 0;
 222
 223 out_mcesa:
 224         nmi_free_per_cpu(lc);
 225 out_async:
 226         stack_free(async_stack);
 227 out:
 228         if (pcpu != &pcpu_devices[0]) {
 229                 free_pages(nodat_stack, THREAD_SIZE_ORDER);
 230                 free_pages((unsigned long) pcpu->lowcore, LC_ORDER);
 231         }
 232         return -ENOMEM;
 233 }
 234
 235 static void pcpu_free_lowcore(struct pcpu *pcpu)
 236 {
 237         unsigned long async_stack, nodat_stack, lowcore;
 238
 239         nodat_stack = pcpu->lowcore->nodat_stack - STACK_INIT_OFFSET;
 240         async_stack = pcpu->lowcore->async_stack - STACK_INIT_OFFSET;
 241         lowcore = (unsigned long) pcpu->lowcore;
 242
 243         pcpu_sigp_retry(pcpu, SIGP_SET_PREFIX, 0);
 244         lowcore_ptr[pcpu - pcpu_devices] = NULL;
 245         vdso_free_per_cpu(pcpu->lowcore);
 246         nmi_free_per_cpu(pcpu->lowcore);
 247         stack_free(async_stack);
 248         if (pcpu == &pcpu_devices[0])
 249                 return;
 250         free_pages(nodat_stack, THREAD_SIZE_ORDER);
 251         free_pages(lowcore, LC_ORDER);
 252 }
 253
 254 static void pcpu_prepare_secondary(struct pcpu *pcpu, int cpu)
 255 {
 256         struct lowcore *lc = pcpu->lowcore;
 257
 258         cpumask_set_cpu(cpu, &init_mm.context.cpu_attach_mask);
 259         cpumask_set_cpu(cpu, mm_cpumask(&init_mm));
 260         lc->cpu_nr = cpu;
 261         lc->spinlock_lockval = arch_spin_lockval(cpu);
 262         lc->spinlock_index = 0;
 263         lc->percpu_offset = __per_cpu_offset[cpu];
 264         lc->kernel_asce = S390_lowcore.kernel_asce;
 265         lc->user_asce = S390_lowcore.kernel_asce;
 266         lc->machine_flags = S390_lowcore.machine_flags;
 267         lc->user_timer = lc->system_timer =
 268                 lc->steal_timer = lc->avg_steal_timer = 0;
 269         __ctl_store(lc->cregs_save_area, 0, 15);
 270         lc->cregs_save_area[1] = lc->kernel_asce;
 271         lc->cregs_save_area[7] = lc->vdso_asce;
 272         save_access_regs((unsigned int *) lc->access_regs_save_area);
 273         memcpy(lc->stfle_fac_list, S390_lowcore.stfle_fac_list,
 274                sizeof(lc->stfle_fac_list));
 275         memcpy(lc->alt_stfle_fac_list, S390_lowcore.alt_stfle_fac_list,
 276                sizeof(lc->alt_stfle_fac_list));
 277         arch_spin_lock_setup(cpu);
 278 }
 279
 280 static void pcpu_attach_task(struct pcpu *pcpu, struct task_struct *tsk)
 281 {
 282         struct lowcore *lc = pcpu->lowcore;
 283
 284         lc->kernel_stack = (unsigned long) task_stack_page(tsk)
 285                 + THREAD_SIZE - STACK_FRAME_OVERHEAD - sizeof(struct pt_regs);
 286         lc->current_task = (unsigned long) tsk;
 287         lc->lpp = LPP_MAGIC;
 288         lc->current_pid = tsk->pid;
 289         lc->user_timer = tsk->thread.user_timer;
 290         lc->guest_timer = tsk->thread.guest_timer;
 291         lc->system_timer = tsk->thread.system_timer;
 292         lc->hardirq_timer = tsk->thread.hardirq_timer;
 293         lc->softirq_timer = tsk->thread.softirq_timer;
 294         lc->steal_timer = 0;
 295 }
 296
 297 static void pcpu_start_fn(struct pcpu *pcpu, void (*func)(void *), void *data)
 298 {
 299         struct lowcore *lc = pcpu->lowcore;
 300
 301         lc->restart_stack = lc->nodat_stack;
 302         lc->restart_fn = (unsigned long) func;
 303         lc->restart_data = (unsigned long) data;
 304         lc->restart_source = -1UL;
 305         pcpu_sigp_retry(pcpu, SIGP_RESTART, 0);
 306 }
 307
 308 /*
 309  * Call function via PSW restart on pcpu and stop the current cpu.
 310  */
 311 static void __pcpu_delegate(void (*func)(void*), void *data)
 312 {
 313         func(data);     /* should not return */
 314 }
 315
 316 static void __no_sanitize_address pcpu_delegate(struct pcpu *pcpu,
 317                                                 void (*func)(void *),
 318                                                 void *data, unsigned long stack)
 319 {
 320         struct lowcore *lc = lowcore_ptr[pcpu - pcpu_devices];
 321         unsigned long source_cpu = stap();
 322
 323         __load_psw_mask(PSW_KERNEL_BITS | PSW_MASK_DAT);
 324         if (pcpu->address == source_cpu)
 325                 CALL_ON_STACK(__pcpu_delegate, stack, 2, func, data);
 326         /* Stop target cpu (if func returns this stops the current cpu). */
 327         pcpu_sigp_retry(pcpu, SIGP_STOP, 0);
 328         /* Restart func on the target cpu and stop the current cpu. */
 329         mem_assign_absolute(lc->restart_stack, stack);
 330         mem_assign_absolute(lc->restart_fn, (unsigned long) func);
 331         mem_assign_absolute(lc->restart_data, (unsigned long) data);
 332         mem_assign_absolute(lc->restart_source, source_cpu);
 333         __bpon();
 334         asm volatile(
 335                 "0:     sigp    0,%0,%2 # sigp restart to target cpu\n"
 336                 "       brc     2,0b    # busy, try again\n"
 337                 "1:     sigp    0,%1,%3 # sigp stop to current cpu\n"
 338                 "       brc     2,1b    # busy, try again\n"
 339                 : : "d" (pcpu->address), "d" (source_cpu),
 340                     "K" (SIGP_RESTART), "K" (SIGP_STOP)
 341                 : "0", "1", "cc");
 342         for (;;) ;
 343 }
 344
 345 /*
 346  * Enable additional logical cpus for multi-threading.
 347  */
 348 static int pcpu_set_smt(unsigned int mtid)
 349 {
 350         int cc;
 351
 352         if (smp_cpu_mtid == mtid)
 353                 return 0;
 354         cc = __pcpu_sigp(0, SIGP_SET_MULTI_THREADING, mtid, NULL);
 355         if (cc == 0) {
 356                 smp_cpu_mtid = mtid;
 357                 smp_cpu_mt_shift = 0;
 358                 while (smp_cpu_mtid >= (1U << smp_cpu_mt_shift))
 359                         smp_cpu_mt_shift++;
 360                 pcpu_devices[0].address = stap();
 361         }
 362         return cc;
 363 }
 364
 365 /*
 366  * Call function on an online CPU.
 367  */
 368 void smp_call_online_cpu(void (*func)(void *), void *data)
 369 {
 370         struct pcpu *pcpu;
 371
 372         /* Use the current cpu if it is online. */
 373         pcpu = pcpu_find_address(cpu_online_mask, stap());
 374         if (!pcpu)
 375                 /* Use the first online cpu. */
 376                 pcpu = pcpu_devices + cpumask_first(cpu_online_mask);
 377         pcpu_delegate(pcpu, func, data, (unsigned long) restart_stack);
 378 }
 379
 380 /*
 381  * Call function on the ipl CPU.
 382  */
 383 void smp_call_ipl_cpu(void (*func)(void *), void *data)
 384 {
 385         struct lowcore *lc = pcpu_devices->lowcore;
 386
 387         if (pcpu_devices[0].address == stap())
 388                 lc = &S390_lowcore;
 389
 390         pcpu_delegate(&pcpu_devices[0], func, data,
 391                       lc->nodat_stack);
 392 }
 393
 394 int smp_find_processor_id(u16 address)
 395 {
 396         int cpu;
 397
 398         for_each_present_cpu(cpu)
 399                 if (pcpu_devices[cpu].address == address)
 400                         return cpu;
 401         return -1;
 402 }
 403
 404 bool arch_vcpu_is_preempted(int cpu)
 405 {
 406         if (test_cpu_flag_of(CIF_ENABLED_WAIT, cpu))
 407                 return false;
 408         if (pcpu_running(pcpu_devices + cpu))
 409                 return false;
 410         return true;
 411 }
 412 EXPORT_SYMBOL(arch_vcpu_is_preempted);
 413
 414 void smp_yield_cpu(int cpu)
 415 {
 416         if (MACHINE_HAS_DIAG9C) {
 417                 diag_stat_inc_norecursion(DIAG_STAT_X09C);
 418                 asm volatile("diag %0,0,0x9c"
 419                              : : "d" (pcpu_devices[cpu].address));
 420         } else if (MACHINE_HAS_DIAG44 && !smp_cpu_mtid) {
 421                 diag_stat_inc_norecursion(DIAG_STAT_X044);
 422                 asm volatile("diag 0,0,0x44");
 423         }
 424 }
 425
 426 /*
 427  * Send cpus emergency shutdown signal. This gives the cpus the
 428  * opportunity to complete outstanding interrupts.
 429  */
 430 void notrace smp_emergency_stop(void)
 431 {
 432         cpumask_t cpumask;
 433         u64 end;
 434         int cpu;
 435
 436         cpumask_copy(&cpumask, cpu_online_mask);
 437         cpumask_clear_cpu(smp_processor_id(), &cpumask);
 438
 439         end = get_tod_clock() + (1000000UL << 12);
 440         for_each_cpu(cpu, &cpumask) {
 441                 struct pcpu *pcpu = pcpu_devices + cpu;
 442                 set_bit(ec_stop_cpu, &pcpu->ec_mask);
 443                 while (__pcpu_sigp(pcpu->address, SIGP_EMERGENCY_SIGNAL,
 444                                    0, NULL) == SIGP_CC_BUSY &&
 445                        get_tod_clock() < end)
 446                         cpu_relax();
 447         }
 448         while (get_tod_clock() < end) {
 449                 for_each_cpu(cpu, &cpumask)
 450                         if (pcpu_stopped(pcpu_devices + cpu))
 451                                 cpumask_clear_cpu(cpu, &cpumask);
 452                 if (cpumask_empty(&cpumask))
 453                         break;
 454                 cpu_relax();
 455         }
 456 }
 457 NOKPROBE_SYMBOL(smp_emergency_stop);
 458
 459 /*
 460  * Stop all cpus but the current one.
 461  */
 462 void smp_send_stop(void)
 463 {
 464         int cpu;
 465
 466         /* Disable all interrupts/machine checks */
 467         __load_psw_mask(PSW_KERNEL_BITS | PSW_MASK_DAT);
 468         trace_hardirqs_off();
 469
 470         debug_set_critical();
 471
 472         if (oops_in_progress)
 473                 smp_emergency_stop();
 474
 475         /* stop all processors */
 476         for_each_online_cpu(cpu) {
 477                 if (cpu == smp_processor_id())
 478                         continue;
 479                 pcpu_sigp_retry(pcpu_devices + cpu, SIGP_STOP, 0);
 480                 while (!pcpu_stopped(pcpu_devices + cpu))
 481                         cpu_relax();
 482         }
 483 }
 484
 485 /*
 486  * This is the main routine where commands issued by other
 487  * cpus are handled.
 488  */
 489 static void smp_handle_ext_call(void)
 490 {
 491         unsigned long bits;
 492
 493         /* handle bit signal external calls */
 494         bits = xchg(&pcpu_devices[smp_processor_id()].ec_mask, 0);
 495         if (test_bit(ec_stop_cpu, &bits))
 496                 smp_stop_cpu();
 497         if (test_bit(ec_schedule, &bits))
 498                 scheduler_ipi();
 499         if (test_bit(ec_call_function_single, &bits))
 500                 generic_smp_call_function_single_interrupt();
 501 }
 502
 503 static void do_ext_call_interrupt(struct ext_code ext_code,
 504                                   unsigned int param32, unsigned long param64)
 505 {
 506         inc_irq_stat(ext_code.code == 0x1202 ? IRQEXT_EXC : IRQEXT_EMS);
 507         smp_handle_ext_call();
 508 }
 509
 510 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
 511 {
 512         int cpu;
 513
 514         for_each_cpu(cpu, mask)
 515                 pcpu_ec_call(pcpu_devices + cpu, ec_call_function_single);
 516 }
 517
 518 void arch_send_call_function_single_ipi(int cpu)
 519 {
 520         pcpu_ec_call(pcpu_devices + cpu, ec_call_function_single);
 521 }
 522
 523 /*
 524  * this function sends a 'reschedule' IPI to another CPU.
 525  * it goes straight through and wastes no time serializing
 526  * anything. Worst case is that we lose a reschedule ...
 527  */
 528 void smp_send_reschedule(int cpu)
 529 {
 530         pcpu_ec_call(pcpu_devices + cpu, ec_schedule);
 531 }
 532
 533 /*
 534  * parameter area for the set/clear control bit callbacks
 535  */
 536 struct ec_creg_mask_parms {
 537         unsigned long orval;
 538         unsigned long andval;
 539         int cr;
 540 };
 541
 542 /*
 543  * callback for setting/clearing control bits
 544  */
 545 static void smp_ctl_bit_callback(void *info)
 546 {
 547         struct ec_creg_mask_parms *pp = info;
 548         unsigned long cregs[16];
 549
 550         __ctl_store(cregs, 0, 15);
 551         cregs[pp->cr] = (cregs[pp->cr] & pp->andval) | pp->orval;
 552         __ctl_load(cregs, 0, 15);
 553 }
 554
 555 /*
 556  * Set a bit in a control register of all cpus
 557  */
 558 void smp_ctl_set_bit(int cr, int bit)
 559 {
 560         struct ec_creg_mask_parms parms = { 1UL << bit, -1UL, cr };
 561
 562         on_each_cpu(smp_ctl_bit_callback, &parms, 1);
 563 }
 564 EXPORT_SYMBOL(smp_ctl_set_bit);
 565
 566 /*
 567  * Clear a bit in a control register of all cpus
 568  */
 569 void smp_ctl_clear_bit(int cr, int bit)
 570 {
 571         struct ec_creg_mask_parms parms = { 0, ~(1UL << bit), cr };
 572
 573         on_each_cpu(smp_ctl_bit_callback, &parms, 1);
 574 }
 575 EXPORT_SYMBOL(smp_ctl_clear_bit);
 576
 577 #ifdef CONFIG_CRASH_DUMP
 578
 579 int smp_store_status(int cpu)
 580 {
 581         struct pcpu *pcpu = pcpu_devices + cpu;
 582         unsigned long pa;
 583
 584         pa = __pa(&pcpu->lowcore->floating_pt_save_area);
 585         if (__pcpu_sigp_relax(pcpu->address, SIGP_STORE_STATUS_AT_ADDRESS,
 586                               pa) != SIGP_CC_ORDER_CODE_ACCEPTED)
 587                 return -EIO;
 588         if (!MACHINE_HAS_VX && !MACHINE_HAS_GS)
 589                 return 0;
 590         pa = __pa(pcpu->lowcore->mcesad & MCESA_ORIGIN_MASK);
 591         if (MACHINE_HAS_GS)
 592                 pa |= pcpu->lowcore->mcesad & MCESA_LC_MASK;
 593         if (__pcpu_sigp_relax(pcpu->address, SIGP_STORE_ADDITIONAL_STATUS,
 594                               pa) != SIGP_CC_ORDER_CODE_ACCEPTED)
 595                 return -EIO;
 596         return 0;
 597 }
 598
 599 /*
 600  * Collect CPU state of the previous, crashed system.
 601  * There are four cases:
 602  * 1) standard zfcp dump
 603  *    condition: OLDMEM_BASE == NULL && ipl_info.type == IPL_TYPE_FCP_DUMP
 604  *    The state for all CPUs except the boot CPU needs to be collected
 605  *    with sigp stop-and-store-status. The boot CPU state is located in
 606  *    the absolute lowcore of the memory stored in the HSA. The zcore code
 607  *    will copy the boot CPU state from the HSA.
 608  * 2) stand-alone kdump for SCSI (zfcp dump with swapped memory)
 609  *    condition: OLDMEM_BASE != NULL && ipl_info.type == IPL_TYPE_FCP_DUMP
 610  *    The state for all CPUs except the boot CPU needs to be collected
 611  *    with sigp stop-and-store-status. The firmware or the boot-loader
 612  *    stored the registers of the boot CPU in the absolute lowcore in the
 613  *    memory of the old system.
 614  * 3) kdump and the old kernel did not store the CPU state,
 615  *    or stand-alone kdump for DASD
 616  *    condition: OLDMEM_BASE != NULL && !is_kdump_kernel()
 617  *    The state for all CPUs except the boot CPU needs to be collected
 618  *    with sigp stop-and-store-status. The kexec code or the boot-loader
 619  *    stored the registers of the boot CPU in the memory of the old system.
 620  * 4) kdump and the old kernel stored the CPU state
 621  *    condition: OLDMEM_BASE != NULL && is_kdump_kernel()
 622  *    This case does not exist for s390 anymore, setup_arch explicitly
 623  *    deactivates the elfcorehdr= kernel parameter
 624  */
 625 static __init void smp_save_cpu_vxrs(struct save_area *sa, u16 addr,
 626                                      bool is_boot_cpu, unsigned long page)
 627 {
 628         __vector128 *vxrs = (__vector128 *) page;
 629
 630         if (is_boot_cpu)
 631                 vxrs = boot_cpu_vector_save_area;
 632         else
 633                 __pcpu_sigp_relax(addr, SIGP_STORE_ADDITIONAL_STATUS, page);
 634         save_area_add_vxrs(sa, vxrs);
 635 }
 636
 637 static __init void smp_save_cpu_regs(struct save_area *sa, u16 addr,
 638                                      bool is_boot_cpu, unsigned long page)
 639 {
 640         void *regs = (void *) page;
 641
 642         if (is_boot_cpu)
 643                 copy_oldmem_kernel(regs, (void *) __LC_FPREGS_SAVE_AREA, 512);
 644         else
 645                 __pcpu_sigp_relax(addr, SIGP_STORE_STATUS_AT_ADDRESS, page);
 646         save_area_add_regs(sa, regs);
 647 }
 648
 649 void __init smp_save_dump_cpus(void)
 650 {
 651         int addr, boot_cpu_addr, max_cpu_addr;
 652         struct save_area *sa;
 653         unsigned long page;
 654         bool is_boot_cpu;
 655
 656         if (!(OLDMEM_BASE || ipl_info.type == IPL_TYPE_FCP_DUMP))
 657                 /* No previous system present, normal boot. */
 658                 return;
 659         /* Allocate a page as dumping area for the store status sigps */
 660         page = memblock_phys_alloc_range(PAGE_SIZE, PAGE_SIZE, 0, 1UL << 31);
 661         if (!page)
 662                 panic("ERROR: Failed to allocate %lx bytes below %lx\n",
 663                       PAGE_SIZE, 1UL << 31);
 664
 665         /* Set multi-threading state to the previous system. */
 666         pcpu_set_smt(sclp.mtid_prev);
 667         boot_cpu_addr = stap();
 668         max_cpu_addr = SCLP_MAX_CORES << sclp.mtid_prev;
 669         for (addr = 0; addr <= max_cpu_addr; addr++) {
 670                 if (__pcpu_sigp_relax(addr, SIGP_SENSE, 0) ==
 671                     SIGP_CC_NOT_OPERATIONAL)
 672                         continue;
 673                 is_boot_cpu = (addr == boot_cpu_addr);
 674                 /* Allocate save area */
 675                 sa = save_area_alloc(is_boot_cpu);
 676                 if (!sa)
 677                         panic("could not allocate memory for save area\n");
 678                 if (MACHINE_HAS_VX)
 679                         /* Get the vector registers */
 680                         smp_save_cpu_vxrs(sa, addr, is_boot_cpu, page);
 681                 /*
 682                  * For a zfcp dump OLDMEM_BASE == NULL and the registers
 683                  * of the boot CPU are stored in the HSA. To retrieve
 684                  * these registers an SCLP request is required which is
 685                  * done by drivers/s390/char/zcore.c:init_cpu_info()
 686                  */
 687                 if (!is_boot_cpu || OLDMEM_BASE)
 688                         /* Get the CPU registers */
 689                         smp_save_cpu_regs(sa, addr, is_boot_cpu, page);
 690         }
 691         memblock_free(page, PAGE_SIZE);
 692         diag_dma_ops.diag308_reset();
 693         pcpu_set_smt(0);
 694 }
 695 #endif /* CONFIG_CRASH_DUMP */
 696
 697 void smp_cpu_set_polarization(int cpu, int val)
 698 {
 699         pcpu_devices[cpu].polarization = val;
 700 }
 701
 702 int smp_cpu_get_polarization(int cpu)
 703 {
 704         return pcpu_devices[cpu].polarization;
 705 }
 706
 707 static void __ref smp_get_core_info(struct sclp_core_info *info, int early)
 708 {
 709         static int use_sigp_detection;
 710         int address;
 711
 712         if (use_sigp_detection || sclp_get_core_info(info, early)) {
 713                 use_sigp_detection = 1;
 714                 for (address = 0;
 715                      address < (SCLP_MAX_CORES << smp_cpu_mt_shift);
 716                      address += (1U << smp_cpu_mt_shift)) {
 717                         if (__pcpu_sigp_relax(address, SIGP_SENSE, 0) ==
 718                             SIGP_CC_NOT_OPERATIONAL)
 719                                 continue;
 720                         info->core[info->configured].core_id =
 721                                 address >> smp_cpu_mt_shift;
 722                         info->configured++;
 723                 }
 724                 info->combined = info->configured;
 725         }
 726 }
 727
 728 static int smp_add_present_cpu(int cpu);
 729
 730 static int smp_add_core(struct sclp_core_entry *core, cpumask_t *avail,
 731                         bool configured, bool early)
 732 {
 733         struct pcpu *pcpu;
 734         int cpu, nr, i;
 735         u16 address;
 736
 737         nr = 0;
 738         if (sclp.has_core_type && core->type != boot_core_type)
 739                 return nr;
 740         cpu = cpumask_first(avail);
 741         address = core->core_id << smp_cpu_mt_shift;
 742         for (i = 0; (i <= smp_cpu_mtid) && (cpu < nr_cpu_ids); i++) {
 743                 if (pcpu_find_address(cpu_present_mask, address + i))
 744                         continue;
 745                 pcpu = pcpu_devices + cpu;
 746                 pcpu->address = address + i;
 747                 if (configured)
 748                         pcpu->state = CPU_STATE_CONFIGURED;
 749                 else
 750                         pcpu->state = CPU_STATE_STANDBY;
 751                 smp_cpu_set_polarization(cpu, POLARIZATION_UNKNOWN);
 752                 set_cpu_present(cpu, true);
 753                 if (!early && smp_add_present_cpu(cpu) != 0)
 754                         set_cpu_present(cpu, false);
 755                 else
 756                         nr++;
 757                 cpumask_clear_cpu(cpu, avail);
 758                 cpu = cpumask_next(cpu, avail);
 759         }
 760         return nr;
 761 }
 762
 763 static int __smp_rescan_cpus(struct sclp_core_info *info, bool early)
 764 {
 765         struct sclp_core_entry *core;
 766         cpumask_t avail;
 767         bool configured;
 768         u16 core_id;
 769         int nr, i;
 770
 771         nr = 0;
 772         cpumask_xor(&avail, cpu_possible_mask, cpu_present_mask);
 773         /*
 774          * Add IPL core first (which got logical CPU number 0) to make sure
 775          * that all SMT threads get subsequent logical CPU numbers.
 776          */
 777         if (early) {
 778                 core_id = pcpu_devices[0].address >> smp_cpu_mt_shift;
 779                 for (i = 0; i < info->configured; i++) {
 780                         core = &info->core[i];
 781                         if (core->core_id == core_id) {
 782                                 nr += smp_add_core(core, &avail, true, early);
 783                                 break;
 784                         }
 785                 }
 786         }
 787         for (i = 0; i < info->combined; i++) {
 788                 configured = i < info->configured;
 789                 nr += smp_add_core(&info->core[i], &avail, configured, early);
 790         }
 791         return nr;
 792 }
 793
 794 void __init smp_detect_cpus(void)
 795 {
 796         unsigned int cpu, mtid, c_cpus, s_cpus;
 797         struct sclp_core_info *info;
 798         u16 address;
 799
 800         /* Get CPU information */
 801         info = memblock_alloc(sizeof(*info), 8);
 802         if (!info)
 803                 panic("%s: Failed to allocate %zu bytes align=0x%x\n",
 804                       __func__, sizeof(*info), 8);
 805         smp_get_core_info(info, 1);
 806         /* Find boot CPU type */
 807         if (sclp.has_core_type) {
 808                 address = stap();
 809                 for (cpu = 0; cpu < info->combined; cpu++)
 810                         if (info->core[cpu].core_id == address) {
 811                                 /* The boot cpu dictates the cpu type. */
 812                                 boot_core_type = info->core[cpu].type;
 813                                 break;
 814                         }
 815                 if (cpu >= info->combined)
 816                         panic("Could not find boot CPU type");
 817         }
 818
 819         /* Set multi-threading state for the current system */
 820         mtid = boot_core_type ? sclp.mtid : sclp.mtid_cp;
 821         mtid = (mtid < smp_max_threads) ? mtid : smp_max_threads - 1;
 822         pcpu_set_smt(mtid);
 823
 824         /* Print number of CPUs */
 825         c_cpus = s_cpus = 0;
 826         for (cpu = 0; cpu < info->combined; cpu++) {
 827                 if (sclp.has_core_type &&
 828                     info->core[cpu].type != boot_core_type)
 829                         continue;
 830                 if (cpu < info->configured)
 831                         c_cpus += smp_cpu_mtid + 1;
 832                 else
 833                         s_cpus += smp_cpu_mtid + 1;
 834         }
 835         pr_info("%d configured CPUs, %d standby CPUs\n", c_cpus, s_cpus);
 836
 837         /* Add CPUs present at boot */
 838         get_online_cpus();
 839         __smp_rescan_cpus(info, true);
 840         put_online_cpus();
 841         memblock_free_early((unsigned long)info, sizeof(*info));
 842 }
 843
 844 static void smp_init_secondary(void)
 845 {
 846         int cpu = smp_processor_id();
 847
 848         S390_lowcore.last_update_clock = get_tod_clock();
 849         restore_access_regs(S390_lowcore.access_regs_save_area);
 850         set_cpu_flag(CIF_ASCE_PRIMARY);
 851         set_cpu_flag(CIF_ASCE_SECONDARY);
 852         cpu_init();
 853         preempt_disable();
 854         init_cpu_timer();
 855         vtime_init();
 856         pfault_init();
 857         notify_cpu_starting(smp_processor_id());
 858         if (topology_cpu_dedicated(cpu))
 859                 set_cpu_flag(CIF_DEDICATED_CPU);
 860         else
 861                 clear_cpu_flag(CIF_DEDICATED_CPU);
 862         set_cpu_online(smp_processor_id(), true);
 863         inc_irq_stat(CPU_RST);
 864         local_irq_enable();
 865         cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
 866 }
 867
 868 /*
 869  *      Activate a secondary processor.
 870  */
 871 static void __no_sanitize_address smp_start_secondary(void *cpuvoid)
 872 {
 873         S390_lowcore.restart_stack = (unsigned long) restart_stack;
 874         S390_lowcore.restart_fn = (unsigned long) do_restart;
 875         S390_lowcore.restart_data = 0;
 876         S390_lowcore.restart_source = -1UL;
 877         __ctl_load(S390_lowcore.cregs_save_area, 0, 15);
 878         __load_psw_mask(PSW_KERNEL_BITS | PSW_MASK_DAT);
 879         CALL_ON_STACK_NORETURN(smp_init_secondary, S390_lowcore.kernel_stack);
 880 }
 881
 882 /* Upping and downing of CPUs */
 883 int __cpu_up(unsigned int cpu, struct task_struct *tidle)
 884 {
 885         struct pcpu *pcpu;
 886         int base, i, rc;
 887
 888         pcpu = pcpu_devices + cpu;
 889         if (pcpu->state != CPU_STATE_CONFIGURED)
 890                 return -EIO;
 891         base = smp_get_base_cpu(cpu);
 892         for (i = 0; i <= smp_cpu_mtid; i++) {
 893                 if (base + i < nr_cpu_ids)
 894                         if (cpu_online(base + i))
 895                                 break;
 896         }
 897         /*
 898          * If this is the first CPU of the core to get online
 899          * do an initial CPU reset.
 900          */
 901         if (i > smp_cpu_mtid &&
 902             pcpu_sigp_retry(pcpu_devices + base, SIGP_INITIAL_CPU_RESET, 0) !=
 903             SIGP_CC_ORDER_CODE_ACCEPTED)
 904                 return -EIO;
 905
 906         rc = pcpu_alloc_lowcore(pcpu, cpu);
 907         if (rc)
 908                 return rc;
 909         pcpu_prepare_secondary(pcpu, cpu);
 910         pcpu_attach_task(pcpu, tidle);
 911         pcpu_start_fn(pcpu, smp_start_secondary, NULL);
 912         /* Wait until cpu puts itself in the online & active maps */
 913         while (!cpu_online(cpu))
 914                 cpu_relax();
 915         return 0;
 916 }
 917
 918 static unsigned int setup_possible_cpus __initdata;
 919
 920 static int __init _setup_possible_cpus(char *s)
 921 {
 922         get_option(&s, &setup_possible_cpus);
 923         return 0;
 924 }
 925 early_param("possible_cpus", _setup_possible_cpus);
 926
 927 int __cpu_disable(void)
 928 {
 929         unsigned long cregs[16];
 930
 931         /* Handle possible pending IPIs */
 932         smp_handle_ext_call();
 933         set_cpu_online(smp_processor_id(), false);
 934         /* Disable pseudo page faults on this cpu. */
 935         pfault_fini();
 936         /* Disable interrupt sources via control register. */
 937         __ctl_store(cregs, 0, 15);
 938         cregs[0]  &= ~0x0000ee70UL;     /* disable all external interrupts */
 939         cregs[6]  &= ~0xff000000UL;     /* disable all I/O interrupts */
 940         cregs[14] &= ~0x1f000000UL;     /* disable most machine checks */
 941         __ctl_load(cregs, 0, 15);
 942         clear_cpu_flag(CIF_NOHZ_DELAY);
 943         return 0;
 944 }
 945
 946 void __cpu_die(unsigned int cpu)
 947 {
 948         struct pcpu *pcpu;
 949
 950         /* Wait until target cpu is down */
 951         pcpu = pcpu_devices + cpu;
 952         while (!pcpu_stopped(pcpu))
 953                 cpu_relax();
 954         pcpu_free_lowcore(pcpu);
 955         cpumask_clear_cpu(cpu, mm_cpumask(&init_mm));
 956         cpumask_clear_cpu(cpu, &init_mm.context.cpu_attach_mask);
 957 }
 958
 959 void __noreturn cpu_die(void)
 960 {
 961         idle_task_exit();
 962         __bpon();
 963         pcpu_sigp_retry(pcpu_devices + smp_processor_id(), SIGP_STOP, 0);
 964         for (;;) ;
 965 }
 966
 967 void __init smp_fill_possible_mask(void)
 968 {
 969         unsigned int possible, sclp_max, cpu;
 970
 971         sclp_max = max(sclp.mtid, sclp.mtid_cp) + 1;
 972         sclp_max = min(smp_max_threads, sclp_max);
 973         sclp_max = (sclp.max_cores * sclp_max) ?: nr_cpu_ids;
 974         possible = setup_possible_cpus ?: nr_cpu_ids;
 975         possible = min(possible, sclp_max);
 976         for (cpu = 0; cpu < possible && cpu < nr_cpu_ids; cpu++)
 977                 set_cpu_possible(cpu, true);
 978 }
 979
 980 void __init smp_prepare_cpus(unsigned int max_cpus)
 981 {
 982         /* request the 0x1201 emergency signal external interrupt */
 983         if (register_external_irq(EXT_IRQ_EMERGENCY_SIG, do_ext_call_interrupt))
 984                 panic("Couldn't request external interrupt 0x1201");
 985         /* request the 0x1202 external call external interrupt */
 986         if (register_external_irq(EXT_IRQ_EXTERNAL_CALL, do_ext_call_interrupt))
 987                 panic("Couldn't request external interrupt 0x1202");
 988 }
 989
 990 void __init smp_prepare_boot_cpu(void)
 991 {
 992         struct pcpu *pcpu = pcpu_devices;
 993
 994         WARN_ON(!cpu_present(0) || !cpu_online(0));
 995         pcpu->state = CPU_STATE_CONFIGURED;
 996         pcpu->lowcore = (struct lowcore *)(unsigned long) store_prefix();
 997         S390_lowcore.percpu_offset = __per_cpu_offset[0];
 998         smp_cpu_set_polarization(0, POLARIZATION_UNKNOWN);
 999 }
1000
1001 void __init smp_cpus_done(unsigned int max_cpus)
1002 {
1003 }
1004
1005 void __init smp_setup_processor_id(void)
1006 {
1007         pcpu_devices[0].address = stap();
1008         S390_lowcore.cpu_nr = 0;
1009         S390_lowcore.spinlock_lockval = arch_spin_lockval(0);
1010         S390_lowcore.spinlock_index = 0;
1011 }
1012
1013 /*
1014  * the frequency of the profiling timer can be changed
1015  * by writing a multiplier value into /proc/profile.
1016  *
1017  * usually you want to run this on all CPUs ;)
1018  */
1019 int setup_profiling_timer(unsigned int multiplier)
1020 {
1021         return 0;
1022 }
1023
1024 static ssize_t cpu_configure_show(struct device *dev,
1025                                   struct device_attribute *attr, char *buf)
1026 {
1027         ssize_t count;
1028
1029         mutex_lock(&smp_cpu_state_mutex);
1030         count = sprintf(buf, "%d\n", pcpu_devices[dev->id].state);
1031         mutex_unlock(&smp_cpu_state_mutex);
1032         return count;
1033 }
1034
1035 static ssize_t cpu_configure_store(struct device *dev,
1036                                    struct device_attribute *attr,
1037                                    const char *buf, size_t count)
1038 {
1039         struct pcpu *pcpu;
1040         int cpu, val, rc, i;
1041         char delim;
1042
1043         if (sscanf(buf, "%d %c", &val, &delim) != 1)
1044                 return -EINVAL;
1045         if (val != 0 && val != 1)
1046                 return -EINVAL;
1047         get_online_cpus();
1048         mutex_lock(&smp_cpu_state_mutex);
1049         rc = -EBUSY;
1050         /* disallow configuration changes of online cpus and cpu 0 */
1051         cpu = dev->id;
1052         cpu = smp_get_base_cpu(cpu);
1053         if (cpu == 0)
1054                 goto out;
1055         for (i = 0; i <= smp_cpu_mtid; i++)
1056                 if (cpu_online(cpu + i))
1057                         goto out;
1058         pcpu = pcpu_devices + cpu;
1059         rc = 0;
1060         switch (val) {
1061         case 0:
1062                 if (pcpu->state != CPU_STATE_CONFIGURED)
1063                         break;
1064                 rc = sclp_core_deconfigure(pcpu->address >> smp_cpu_mt_shift);
1065                 if (rc)
1066                         break;
1067                 for (i = 0; i <= smp_cpu_mtid; i++) {
1068                         if (cpu + i >= nr_cpu_ids || !cpu_present(cpu + i))
1069                                 continue;
1070                         pcpu[i].state = CPU_STATE_STANDBY;
1071                         smp_cpu_set_polarization(cpu + i,
1072                                                  POLARIZATION_UNKNOWN);
1073                 }
1074                 topology_expect_change();
1075                 break;
1076         case 1:
1077                 if (pcpu->state != CPU_STATE_STANDBY)
1078                         break;
1079                 rc = sclp_core_configure(pcpu->address >> smp_cpu_mt_shift);
1080                 if (rc)
1081                         break;
1082                 for (i = 0; i <= smp_cpu_mtid; i++) {
1083                         if (cpu + i >= nr_cpu_ids || !cpu_present(cpu + i))
1084                                 continue;
1085                         pcpu[i].state = CPU_STATE_CONFIGURED;
1086                         smp_cpu_set_polarization(cpu + i,
1087                                                  POLARIZATION_UNKNOWN);
1088                 }
1089                 topology_expect_change();
1090                 break;
1091         default:
1092                 break;
1093         }
1094 out:
1095         mutex_unlock(&smp_cpu_state_mutex);
1096         put_online_cpus();
1097         return rc ? rc : count;
1098 }
1099 static DEVICE_ATTR(configure, 0644, cpu_configure_show, cpu_configure_store);
1100
1101 static ssize_t show_cpu_address(struct device *dev,
1102                                 struct device_attribute *attr, char *buf)
1103 {
1104         return sprintf(buf, "%d\n", pcpu_devices[dev->id].address);
1105 }
1106 static DEVICE_ATTR(address, 0444, show_cpu_address, NULL);
1107
1108 static struct attribute *cpu_common_attrs[] = {
1109         &dev_attr_configure.attr,
1110         &dev_attr_address.attr,
1111         NULL,
1112 };
1113
1114 static struct attribute_group cpu_common_attr_group = {
1115         .attrs = cpu_common_attrs,
1116 };
1117
1118 static struct attribute *cpu_online_attrs[] = {
1119         &dev_attr_idle_count.attr,
1120         &dev_attr_idle_time_us.attr,
1121         NULL,
1122 };
1123
1124 static struct attribute_group cpu_online_attr_group = {
1125         .attrs = cpu_online_attrs,
1126 };
1127
1128 static int smp_cpu_online(unsigned int cpu)
1129 {
1130         struct device *s = &per_cpu(cpu_device, cpu)->dev;
1131
1132         return sysfs_create_group(&s->kobj, &cpu_online_attr_group);
1133 }
1134 static int smp_cpu_pre_down(unsigned int cpu)
1135 {
1136         struct device *s = &per_cpu(cpu_device, cpu)->dev;
1137
1138         sysfs_remove_group(&s->kobj, &cpu_online_attr_group);
1139         return 0;
1140 }
1141
1142 static int smp_add_present_cpu(int cpu)
1143 {
1144         struct device *s;
1145         struct cpu *c;
1146         int rc;
1147
1148         c = kzalloc(sizeof(*c), GFP_KERNEL);
1149         if (!c)
1150                 return -ENOMEM;
1151         per_cpu(cpu_device, cpu) = c;
1152         s = &c->dev;
1153         c->hotpluggable = 1;
1154         rc = register_cpu(c, cpu);
1155         if (rc)
1156                 goto out;
1157         rc = sysfs_create_group(&s->kobj, &cpu_common_attr_group);
1158         if (rc)
1159                 goto out_cpu;
1160         rc = topology_cpu_init(c);
1161         if (rc)
1162                 goto out_topology;
1163         return 0;
1164
1165 out_topology:
1166         sysfs_remove_group(&s->kobj, &cpu_common_attr_group);
1167 out_cpu:
1168         unregister_cpu(c);
1169 out:
1170         return rc;
1171 }
1172
1173 int __ref smp_rescan_cpus(void)
1174 {
1175         struct sclp_core_info *info;
1176         int nr;
1177
1178         info = kzalloc(sizeof(*info), GFP_KERNEL);
1179         if (!info)
1180                 return -ENOMEM;
1181         smp_get_core_info(info, 0);
1182         get_online_cpus();
1183         mutex_lock(&smp_cpu_state_mutex);
1184         nr = __smp_rescan_cpus(info, false);
1185         mutex_unlock(&smp_cpu_state_mutex);
1186         put_online_cpus();
1187         kfree(info);
1188         if (nr)
1189                 topology_schedule_update();
1190         return 0;
1191 }
1192
1193 static ssize_t __ref rescan_store(struct device *dev,
1194                                   struct device_attribute *attr,
1195                                   const char *buf,
1196                                   size_t count)
1197 {
1198         int rc;
1199
1200         rc = lock_device_hotplug_sysfs();
1201         if (rc)
1202                 return rc;
1203         rc = smp_rescan_cpus();
1204         unlock_device_hotplug();
1205         return rc ? rc : count;
1206 }
1207 static DEVICE_ATTR_WO(rescan);
1208
1209 static int __init s390_smp_init(void)
1210 {
1211         int cpu, rc = 0;
1212
1213         rc = device_create_file(cpu_subsys.dev_root, &dev_attr_rescan);
1214         if (rc)
1215                 return rc;
1216         for_each_present_cpu(cpu) {
1217                 rc = smp_add_present_cpu(cpu);
1218                 if (rc)
1219                         goto out;
1220         }
1221
1222         rc = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "s390/smp:online",
1223                                smp_cpu_online, smp_cpu_pre_down);
1224         rc = rc <= 0 ? rc : 0;
1225 out:
1226         return rc;
1227 }
1228 subsys_initcall(s390_smp_init);