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