arch/s390/kernel/smp.c

   1 /*
   2  *  SMP related functions
   3  *
   4  *    Copyright IBM Corp. 1999, 2012
   5  *    Author(s): Denis Joseph Barrow,
   6  *               Martin Schwidefsky <schwidefsky@de.ibm.com>,
   7  *               Heiko Carstens <heiko.carstens@de.ibm.com>,
   8  *
   9  *  based on other smp stuff by
  10  *    (c) 1995 Alan Cox, CymruNET Ltd  <alan@cymru.net>
  11  *    (c) 1998 Ingo Molnar
  12  *
  13  * The code outside of smp.c uses logical cpu numbers, only smp.c does
  14  * the translation of logical to physical cpu ids. All new code that
  15  * operates on physical cpu numbers needs to go into smp.c.
  16  */
  17
  18 #define KMSG_COMPONENT "cpu"
  19 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
  20
  21 #include <linux/workqueue.h>
  22 #include <linux/module.h>
  23 #include <linux/init.h>
  24 #include <linux/mm.h>
  25 #include <linux/err.h>
  26 #include <linux/spinlock.h>
  27 #include <linux/kernel_stat.h>
  28 #include <linux/delay.h>
  29 #include <linux/interrupt.h>
  30 #include <linux/irqflags.h>
  31 #include <linux/cpu.h>
  32 #include <linux/slab.h>
  33 #include <linux/crash_dump.h>
  34 #include <linux/memblock.h>
  35 #include <asm/asm-offsets.h>
  36 #include <asm/diag.h>
  37 #include <asm/switch_to.h>
  38 #include <asm/facility.h>
  39 #include <asm/ipl.h>
  40 #include <asm/setup.h>
  41 #include <asm/irq.h>
  42 #include <asm/tlbflush.h>
  43 #include <asm/vtimer.h>
  44 #include <asm/lowcore.h>
  45 #include <asm/sclp.h>
  46 #include <asm/vdso.h>
  47 #include <asm/debug.h>
  48 #include <asm/os_info.h>
  49 #include <asm/sigp.h>
  50 #include <asm/idle.h>
  51 #include "entry.h"
  52
  53 enum {
  54         ec_schedule = 0,
  55         ec_call_function_single,
  56         ec_stop_cpu,
  57 };
  58
  59 enum {
  60         CPU_STATE_STANDBY,
  61         CPU_STATE_CONFIGURED,
  62 };
  63
  64 static DEFINE_PER_CPU(struct cpu *, cpu_device);
  65
  66 struct pcpu {
  67         struct _lowcore *lowcore;       /* lowcore page(s) for the cpu */
  68         unsigned long ec_mask;          /* bit mask for ec_xxx functions */
  69         signed char state;              /* physical cpu state */
  70         signed char polarization;       /* physical polarization */
  71         u16 address;                    /* physical cpu address */
  72 };
  73
  74 static u8 boot_core_type;
  75 static struct pcpu pcpu_devices[NR_CPUS];
  76
  77 unsigned int smp_cpu_mt_shift;
  78 EXPORT_SYMBOL(smp_cpu_mt_shift);
  79
  80 unsigned int smp_cpu_mtid;
  81 EXPORT_SYMBOL(smp_cpu_mtid);
  82
  83 static unsigned int smp_max_threads __initdata = -1U;
  84
  85 static int __init early_nosmt(char *s)
  86 {
  87         smp_max_threads = 1;
  88         return 0;
  89 }
  90 early_param("nosmt", early_nosmt);
  91
  92 static int __init early_smt(char *s)
  93 {
  94         get_option(&s, &smp_max_threads);
  95         return 0;
  96 }
  97 early_param("smt", early_smt);
  98
  99 /*
 100  * The smp_cpu_state_mutex must be held when changing the state or polarization
 101  * member of a pcpu data structure within the pcpu_devices arreay.
 102  */
 103 DEFINE_MUTEX(smp_cpu_state_mutex);
 104
 105 /*
 106  * Signal processor helper functions.
 107  */
 108 static inline int __pcpu_sigp_relax(u16 addr, u8 order, unsigned long parm,
 109                                     u32 *status)
 110 {
 111         int cc;
 112
 113         while (1) {
 114                 cc = __pcpu_sigp(addr, order, parm, NULL);
 115                 if (cc != SIGP_CC_BUSY)
 116                         return cc;
 117                 cpu_relax();
 118         }
 119 }
 120
 121 static int pcpu_sigp_retry(struct pcpu *pcpu, u8 order, u32 parm)
 122 {
 123         int cc, retry;
 124
 125         for (retry = 0; ; retry++) {
 126                 cc = __pcpu_sigp(pcpu->address, order, parm, NULL);
 127                 if (cc != SIGP_CC_BUSY)
 128                         break;
 129                 if (retry >= 3)
 130                         udelay(10);
 131         }
 132         return cc;
 133 }
 134
 135 static inline int pcpu_stopped(struct pcpu *pcpu)
 136 {
 137         u32 uninitialized_var(status);
 138
 139         if (__pcpu_sigp(pcpu->address, SIGP_SENSE,
 140                         0, &status) != SIGP_CC_STATUS_STORED)
 141                 return 0;
 142         return !!(status & (SIGP_STATUS_CHECK_STOP|SIGP_STATUS_STOPPED));
 143 }
 144
 145 static inline int pcpu_running(struct pcpu *pcpu)
 146 {
 147         if (__pcpu_sigp(pcpu->address, SIGP_SENSE_RUNNING,
 148                         0, NULL) != SIGP_CC_STATUS_STORED)
 149                 return 1;
 150         /* Status stored condition code is equivalent to cpu not running. */
 151         return 0;
 152 }
 153
 154 /*
 155  * Find struct pcpu by cpu address.
 156  */
 157 static struct pcpu *pcpu_find_address(const struct cpumask *mask, u16 address)
 158 {
 159         int cpu;
 160
 161         for_each_cpu(cpu, mask)
 162                 if (pcpu_devices[cpu].address == address)
 163                         return pcpu_devices + cpu;
 164         return NULL;
 165 }
 166
 167 static void pcpu_ec_call(struct pcpu *pcpu, int ec_bit)
 168 {
 169         int order;
 170
 171         if (test_and_set_bit(ec_bit, &pcpu->ec_mask))
 172                 return;
 173         order = pcpu_running(pcpu) ? SIGP_EXTERNAL_CALL : SIGP_EMERGENCY_SIGNAL;
 174         pcpu_sigp_retry(pcpu, order, 0);
 175 }
 176
 177 #define ASYNC_FRAME_OFFSET (ASYNC_SIZE - STACK_FRAME_OVERHEAD - __PT_SIZE)
 178 #define PANIC_FRAME_OFFSET (PAGE_SIZE - STACK_FRAME_OVERHEAD - __PT_SIZE)
 179
 180 static int pcpu_alloc_lowcore(struct pcpu *pcpu, int cpu)
 181 {
 182         unsigned long async_stack, panic_stack;
 183         struct _lowcore *lc;
 184
 185         if (pcpu != &pcpu_devices[0]) {
 186                 pcpu->lowcore = (struct _lowcore *)
 187                         __get_free_pages(GFP_KERNEL | GFP_DMA, LC_ORDER);
 188                 async_stack = __get_free_pages(GFP_KERNEL, ASYNC_ORDER);
 189                 panic_stack = __get_free_page(GFP_KERNEL);
 190                 if (!pcpu->lowcore || !panic_stack || !async_stack)
 191                         goto out;
 192         } else {
 193                 async_stack = pcpu->lowcore->async_stack - ASYNC_FRAME_OFFSET;
 194                 panic_stack = pcpu->lowcore->panic_stack - PANIC_FRAME_OFFSET;
 195         }
 196         lc = pcpu->lowcore;
 197         memcpy(lc, &S390_lowcore, 512);
 198         memset((char *) lc + 512, 0, sizeof(*lc) - 512);
 199         lc->async_stack = async_stack + ASYNC_FRAME_OFFSET;
 200         lc->panic_stack = panic_stack + PANIC_FRAME_OFFSET;
 201         lc->cpu_nr = cpu;
 202         lc->spinlock_lockval = arch_spin_lockval(cpu);
 203         lc->br_r1_trampoline = 0x07f1;  /* br %r1 */
 204         if (MACHINE_HAS_VX)
 205                 lc->vector_save_area_addr =
 206                         (unsigned long) &lc->vector_save_area;
 207         if (vdso_alloc_per_cpu(lc))
 208                 goto out;
 209         lowcore_ptr[cpu] = lc;
 210         pcpu_sigp_retry(pcpu, SIGP_SET_PREFIX, (u32)(unsigned long) lc);
 211         return 0;
 212 out:
 213         if (pcpu != &pcpu_devices[0]) {
 214                 free_page(panic_stack);
 215                 free_pages(async_stack, ASYNC_ORDER);
 216                 free_pages((unsigned long) pcpu->lowcore, LC_ORDER);
 217         }
 218         return -ENOMEM;
 219 }
 220
 221 #ifdef CONFIG_HOTPLUG_CPU
 222
 223 static void pcpu_free_lowcore(struct pcpu *pcpu)
 224 {
 225         pcpu_sigp_retry(pcpu, SIGP_SET_PREFIX, 0);
 226         lowcore_ptr[pcpu - pcpu_devices] = NULL;
 227         vdso_free_per_cpu(pcpu->lowcore);
 228         if (pcpu == &pcpu_devices[0])
 229                 return;
 230         free_page(pcpu->lowcore->panic_stack-PANIC_FRAME_OFFSET);
 231         free_pages(pcpu->lowcore->async_stack-ASYNC_FRAME_OFFSET, ASYNC_ORDER);
 232         free_pages((unsigned long) pcpu->lowcore, LC_ORDER);
 233 }
 234
 235 #endif /* CONFIG_HOTPLUG_CPU */
 236
 237 static void pcpu_prepare_secondary(struct pcpu *pcpu, int cpu)
 238 {
 239         struct _lowcore *lc = pcpu->lowcore;
 240
 241         if (MACHINE_HAS_TLB_LC)
 242                 cpumask_set_cpu(cpu, &init_mm.context.cpu_attach_mask);
 243         cpumask_set_cpu(cpu, mm_cpumask(&init_mm));
 244         atomic_inc(&init_mm.context.attach_count);
 245         lc->cpu_nr = cpu;
 246         lc->spinlock_lockval = arch_spin_lockval(cpu);
 247         lc->percpu_offset = __per_cpu_offset[cpu];
 248         lc->kernel_asce = S390_lowcore.kernel_asce;
 249         lc->machine_flags = S390_lowcore.machine_flags;
 250         lc->user_timer = lc->system_timer = lc->steal_timer = 0;
 251         __ctl_store(lc->cregs_save_area, 0, 15);
 252         save_access_regs((unsigned int *) lc->access_regs_save_area);
 253         memcpy(lc->stfle_fac_list, S390_lowcore.stfle_fac_list,
 254                sizeof(lc->stfle_fac_list));
 255         memcpy(lc->alt_stfle_fac_list, S390_lowcore.alt_stfle_fac_list,
 256                sizeof(lc->alt_stfle_fac_list));
 257 }
 258
 259 static void pcpu_attach_task(struct pcpu *pcpu, struct task_struct *tsk)
 260 {
 261         struct _lowcore *lc = pcpu->lowcore;
 262         struct thread_info *ti = task_thread_info(tsk);
 263
 264         lc->kernel_stack = (unsigned long) task_stack_page(tsk)
 265                 + THREAD_SIZE - STACK_FRAME_OVERHEAD - sizeof(struct pt_regs);
 266         lc->thread_info = (unsigned long) task_thread_info(tsk);
 267         lc->current_task = (unsigned long) tsk;
 268         lc->lpp = LPP_MAGIC;
 269         lc->current_pid = tsk->pid;
 270         lc->user_timer = ti->user_timer;
 271         lc->system_timer = ti->system_timer;
 272         lc->steal_timer = 0;
 273 }
 274
 275 static void pcpu_start_fn(struct pcpu *pcpu, void (*func)(void *), void *data)
 276 {
 277         struct _lowcore *lc = pcpu->lowcore;
 278
 279         lc->restart_stack = lc->kernel_stack;
 280         lc->restart_fn = (unsigned long) func;
 281         lc->restart_data = (unsigned long) data;
 282         lc->restart_source = -1UL;
 283         pcpu_sigp_retry(pcpu, SIGP_RESTART, 0);
 284 }
 285
 286 /*
 287  * Call function via PSW restart on pcpu and stop the current cpu.
 288  */
 289 static void pcpu_delegate(struct pcpu *pcpu, void (*func)(void *),
 290                           void *data, unsigned long stack)
 291 {
 292         struct _lowcore *lc = lowcore_ptr[pcpu - pcpu_devices];
 293         unsigned long source_cpu = stap();
 294
 295         __load_psw_mask(PSW_KERNEL_BITS);
 296         if (pcpu->address == source_cpu)
 297                 func(data);     /* should not return */
 298         /* Stop target cpu (if func returns this stops the current cpu). */
 299         pcpu_sigp_retry(pcpu, SIGP_STOP, 0);
 300         /* Restart func on the target cpu and stop the current cpu. */
 301         mem_assign_absolute(lc->restart_stack, stack);
 302         mem_assign_absolute(lc->restart_fn, (unsigned long) func);
 303         mem_assign_absolute(lc->restart_data, (unsigned long) data);
 304         mem_assign_absolute(lc->restart_source, source_cpu);
 305         __bpon();
 306         asm volatile(
 307                 "0:     sigp    0,%0,%2 # sigp restart to target cpu\n"
 308                 "       brc     2,0b    # busy, try again\n"
 309                 "1:     sigp    0,%1,%3 # sigp stop to current cpu\n"
 310                 "       brc     2,1b    # busy, try again\n"
 311                 : : "d" (pcpu->address), "d" (source_cpu),
 312                     "K" (SIGP_RESTART), "K" (SIGP_STOP)
 313                 : "0", "1", "cc");
 314         for (;;) ;
 315 }
 316
 317 /*
 318  * Enable additional logical cpus for multi-threading.
 319  */
 320 static int pcpu_set_smt(unsigned int mtid)
 321 {
 322         register unsigned long reg1 asm ("1") = (unsigned long) mtid;
 323         int cc;
 324
 325         if (smp_cpu_mtid == mtid)
 326                 return 0;
 327         asm volatile(
 328                 "       sigp    %1,0,%2 # sigp set multi-threading\n"
 329                 "       ipm     %0\n"
 330                 "       srl     %0,28\n"
 331                 : "=d" (cc) : "d" (reg1), "K" (SIGP_SET_MULTI_THREADING)
 332                 : "cc");
 333         if (cc == 0) {
 334                 smp_cpu_mtid = mtid;
 335                 smp_cpu_mt_shift = 0;
 336                 while (smp_cpu_mtid >= (1U << smp_cpu_mt_shift))
 337                         smp_cpu_mt_shift++;
 338                 pcpu_devices[0].address = stap();
 339         }
 340         return cc;
 341 }
 342
 343 /*
 344  * Call function on an online CPU.
 345  */
 346 void smp_call_online_cpu(void (*func)(void *), void *data)
 347 {
 348         struct pcpu *pcpu;
 349
 350         /* Use the current cpu if it is online. */
 351         pcpu = pcpu_find_address(cpu_online_mask, stap());
 352         if (!pcpu)
 353                 /* Use the first online cpu. */
 354                 pcpu = pcpu_devices + cpumask_first(cpu_online_mask);
 355         pcpu_delegate(pcpu, func, data, (unsigned long) restart_stack);
 356 }
 357
 358 /*
 359  * Call function on the ipl CPU.
 360  */
 361 void smp_call_ipl_cpu(void (*func)(void *), void *data)
 362 {
 363         struct _lowcore *lc = pcpu_devices->lowcore;
 364
 365         if (pcpu_devices[0].address == stap())
 366                 lc = &S390_lowcore;
 367
 368         pcpu_delegate(&pcpu_devices[0], func, data,
 369                       lc->panic_stack - PANIC_FRAME_OFFSET + PAGE_SIZE);
 370 }
 371
 372 int smp_find_processor_id(u16 address)
 373 {
 374         int cpu;
 375
 376         for_each_present_cpu(cpu)
 377                 if (pcpu_devices[cpu].address == address)
 378                         return cpu;
 379         return -1;
 380 }
 381
 382 int smp_vcpu_scheduled(int cpu)
 383 {
 384         return pcpu_running(pcpu_devices + cpu);
 385 }
 386
 387 void smp_yield_cpu(int cpu)
 388 {
 389         if (MACHINE_HAS_DIAG9C) {
 390                 diag_stat_inc_norecursion(DIAG_STAT_X09C);
 391                 asm volatile("diag %0,0,0x9c"
 392                              : : "d" (pcpu_devices[cpu].address));
 393         } else if (MACHINE_HAS_DIAG44) {
 394                 diag_stat_inc_norecursion(DIAG_STAT_X044);
 395                 asm volatile("diag 0,0,0x44");
 396         }
 397 }
 398
 399 /*
 400  * Send cpus emergency shutdown signal. This gives the cpus the
 401  * opportunity to complete outstanding interrupts.
 402  */
 403 static void smp_emergency_stop(cpumask_t *cpumask)
 404 {
 405         u64 end;
 406         int cpu;
 407
 408         end = get_tod_clock() + (1000000UL << 12);
 409         for_each_cpu(cpu, cpumask) {
 410                 struct pcpu *pcpu = pcpu_devices + cpu;
 411                 set_bit(ec_stop_cpu, &pcpu->ec_mask);
 412                 while (__pcpu_sigp(pcpu->address, SIGP_EMERGENCY_SIGNAL,
 413                                    0, NULL) == SIGP_CC_BUSY &&
 414                        get_tod_clock() < end)
 415                         cpu_relax();
 416         }
 417         while (get_tod_clock() < end) {
 418                 for_each_cpu(cpu, cpumask)
 419                         if (pcpu_stopped(pcpu_devices + cpu))
 420                                 cpumask_clear_cpu(cpu, cpumask);
 421                 if (cpumask_empty(cpumask))
 422                         break;
 423                 cpu_relax();
 424         }
 425 }
 426
 427 /*
 428  * Stop all cpus but the current one.
 429  */
 430 void smp_send_stop(void)
 431 {
 432         cpumask_t cpumask;
 433         int cpu;
 434
 435         /* Disable all interrupts/machine checks */
 436         __load_psw_mask(PSW_KERNEL_BITS | PSW_MASK_DAT);
 437         trace_hardirqs_off();
 438
 439         debug_set_critical();
 440         cpumask_copy(&cpumask, cpu_online_mask);
 441         cpumask_clear_cpu(smp_processor_id(), &cpumask);
 442
 443         if (oops_in_progress)
 444                 smp_emergency_stop(&cpumask);
 445
 446         /* stop all processors */
 447         for_each_cpu(cpu, &cpumask) {
 448                 struct pcpu *pcpu = pcpu_devices + cpu;
 449                 pcpu_sigp_retry(pcpu, SIGP_STOP, 0);
 450                 while (!pcpu_stopped(pcpu))
 451                         cpu_relax();
 452         }
 453 }
 454
 455 /*
 456  * This is the main routine where commands issued by other
 457  * cpus are handled.
 458  */
 459 static void smp_handle_ext_call(void)
 460 {
 461         unsigned long bits;
 462
 463         /* handle bit signal external calls */
 464         bits = xchg(&pcpu_devices[smp_processor_id()].ec_mask, 0);
 465         if (test_bit(ec_stop_cpu, &bits))
 466                 smp_stop_cpu();
 467         if (test_bit(ec_schedule, &bits))
 468                 scheduler_ipi();
 469         if (test_bit(ec_call_function_single, &bits))
 470                 generic_smp_call_function_single_interrupt();
 471 }
 472
 473 static void do_ext_call_interrupt(struct ext_code ext_code,
 474                                   unsigned int param32, unsigned long param64)
 475 {
 476         inc_irq_stat(ext_code.code == 0x1202 ? IRQEXT_EXC : IRQEXT_EMS);
 477         smp_handle_ext_call();
 478 }
 479
 480 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
 481 {
 482         int cpu;
 483
 484         for_each_cpu(cpu, mask)
 485                 pcpu_ec_call(pcpu_devices + cpu, ec_call_function_single);
 486 }
 487
 488 void arch_send_call_function_single_ipi(int cpu)
 489 {
 490         pcpu_ec_call(pcpu_devices + cpu, ec_call_function_single);
 491 }
 492
 493 /*
 494  * this function sends a 'reschedule' IPI to another CPU.
 495  * it goes straight through and wastes no time serializing
 496  * anything. Worst case is that we lose a reschedule ...
 497  */
 498 void smp_send_reschedule(int cpu)
 499 {
 500         pcpu_ec_call(pcpu_devices + cpu, ec_schedule);
 501 }
 502
 503 /*
 504  * parameter area for the set/clear control bit callbacks
 505  */
 506 struct ec_creg_mask_parms {
 507         unsigned long orval;
 508         unsigned long andval;
 509         int cr;
 510 };
 511
 512 /*
 513  * callback for setting/clearing control bits
 514  */
 515 static void smp_ctl_bit_callback(void *info)
 516 {
 517         struct ec_creg_mask_parms *pp = info;
 518         unsigned long cregs[16];
 519
 520         __ctl_store(cregs, 0, 15);
 521         cregs[pp->cr] = (cregs[pp->cr] & pp->andval) | pp->orval;
 522         __ctl_load(cregs, 0, 15);
 523 }
 524
 525 /*
 526  * Set a bit in a control register of all cpus
 527  */
 528 void smp_ctl_set_bit(int cr, int bit)
 529 {
 530         struct ec_creg_mask_parms parms = { 1UL << bit, -1UL, cr };
 531
 532         on_each_cpu(smp_ctl_bit_callback, &parms, 1);
 533 }
 534 EXPORT_SYMBOL(smp_ctl_set_bit);
 535
 536 /*
 537  * Clear a bit in a control register of all cpus
 538  */
 539 void smp_ctl_clear_bit(int cr, int bit)
 540 {
 541         struct ec_creg_mask_parms parms = { 0, ~(1UL << bit), cr };
 542
 543         on_each_cpu(smp_ctl_bit_callback, &parms, 1);
 544 }
 545 EXPORT_SYMBOL(smp_ctl_clear_bit);
 546
 547 #ifdef CONFIG_CRASH_DUMP
 548
 549 static void __init __smp_store_cpu_state(struct save_area_ext *sa_ext,
 550                                          u16 address, int is_boot_cpu)
 551 {
 552         void *lc = (void *)(unsigned long) store_prefix();
 553         unsigned long vx_sa;
 554
 555         if (is_boot_cpu) {
 556                 /* Copy the registers of the boot CPU. */
 557                 copy_oldmem_page(1, (void *) &sa_ext->sa, sizeof(sa_ext->sa),
 558                                  SAVE_AREA_BASE - PAGE_SIZE, 0);
 559                 if (MACHINE_HAS_VX)
 560                         save_vx_regs_safe(sa_ext->vx_regs);
 561                 return;
 562         }
 563         /* Get the registers of a non-boot cpu. */
 564         __pcpu_sigp_relax(address, SIGP_STOP_AND_STORE_STATUS, 0, NULL);
 565         memcpy_real(&sa_ext->sa, lc + SAVE_AREA_BASE, sizeof(sa_ext->sa));
 566         if (!MACHINE_HAS_VX)
 567                 return;
 568         /* Get the VX registers */
 569         vx_sa = memblock_alloc(PAGE_SIZE, PAGE_SIZE);
 570         if (!vx_sa)
 571                 panic("could not allocate memory for VX save area\n");
 572         __pcpu_sigp_relax(address, SIGP_STORE_ADDITIONAL_STATUS, vx_sa, NULL);
 573         memcpy(sa_ext->vx_regs, (void *) vx_sa, sizeof(sa_ext->vx_regs));
 574         memblock_free(vx_sa, PAGE_SIZE);
 575 }
 576
 577 int smp_store_status(int cpu)
 578 {
 579         unsigned long vx_sa;
 580         struct pcpu *pcpu;
 581
 582         pcpu = pcpu_devices + cpu;
 583         if (__pcpu_sigp_relax(pcpu->address, SIGP_STOP_AND_STORE_STATUS,
 584                               0, NULL) != SIGP_CC_ORDER_CODE_ACCEPTED)
 585                 return -EIO;
 586         if (!MACHINE_HAS_VX)
 587                 return 0;
 588         vx_sa = __pa(pcpu->lowcore->vector_save_area_addr);
 589         __pcpu_sigp_relax(pcpu->address, SIGP_STORE_ADDITIONAL_STATUS,
 590                           vx_sa, NULL);
 591         return 0;
 592 }
 593
 594 #endif /* CONFIG_CRASH_DUMP */
 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 allocate the save area and 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  *    The state of all CPUs is stored in ELF sections in the memory of the
 620  *    old system. The ELF sections are picked up by the crash_dump code
 621  *    via elfcorehdr_addr.
 622  */
 623 void __init smp_save_dump_cpus(void)
 624 {
 625 #ifdef CONFIG_CRASH_DUMP
 626         int addr, cpu, boot_cpu_addr, max_cpu_addr;
 627         struct save_area_ext *sa_ext;
 628         bool is_boot_cpu;
 629
 630         if (is_kdump_kernel())
 631                 /* Previous system stored the CPU states. Nothing to do. */
 632                 return;
 633         if (!(OLDMEM_BASE || ipl_info.type == IPL_TYPE_FCP_DUMP))
 634                 /* No previous system present, normal boot. */
 635                 return;
 636         /* Set multi-threading state to the previous system. */
 637         pcpu_set_smt(sclp.mtid_prev);
 638         max_cpu_addr = SCLP_MAX_CORES << sclp.mtid_prev;
 639         for (cpu = 0, addr = 0; addr <= max_cpu_addr; addr++) {
 640                 if (__pcpu_sigp_relax(addr, SIGP_SENSE, 0, NULL) ==
 641                     SIGP_CC_NOT_OPERATIONAL)
 642                         continue;
 643                 cpu += 1;
 644         }
 645         dump_save_areas.areas = (void *)memblock_alloc(sizeof(void *) * cpu, 8);
 646         dump_save_areas.count = cpu;
 647         boot_cpu_addr = stap();
 648         for (cpu = 0, addr = 0; addr <= max_cpu_addr; addr++) {
 649                 if (__pcpu_sigp_relax(addr, SIGP_SENSE, 0, NULL) ==
 650                     SIGP_CC_NOT_OPERATIONAL)
 651                         continue;
 652                 sa_ext = (void *) memblock_alloc(sizeof(*sa_ext), 8);
 653                 dump_save_areas.areas[cpu] = sa_ext;
 654                 if (!sa_ext)
 655                         panic("could not allocate memory for save area\n");
 656                 is_boot_cpu = (addr == boot_cpu_addr);
 657                 cpu += 1;
 658                 if (is_boot_cpu && !OLDMEM_BASE)
 659                         /* Skip boot CPU for standard zfcp dump. */
 660                         continue;
 661                 /* Get state for this CPU. */
 662                 __smp_store_cpu_state(sa_ext, addr, is_boot_cpu);
 663         }
 664         diag308_reset();
 665         pcpu_set_smt(0);
 666 #endif /* CONFIG_CRASH_DUMP */
 667 }
 668
 669 void smp_cpu_set_polarization(int cpu, int val)
 670 {
 671         pcpu_devices[cpu].polarization = val;
 672 }
 673
 674 int smp_cpu_get_polarization(int cpu)
 675 {
 676         return pcpu_devices[cpu].polarization;
 677 }
 678
 679 static struct sclp_core_info *smp_get_core_info(void)
 680 {
 681         static int use_sigp_detection;
 682         struct sclp_core_info *info;
 683         int address;
 684
 685         info = kzalloc(sizeof(*info), GFP_KERNEL);
 686         if (info && (use_sigp_detection || sclp_get_core_info(info))) {
 687                 use_sigp_detection = 1;
 688                 for (address = 0;
 689                      address < (SCLP_MAX_CORES << smp_cpu_mt_shift);
 690                      address += (1U << smp_cpu_mt_shift)) {
 691                         if (__pcpu_sigp_relax(address, SIGP_SENSE, 0, NULL) ==
 692                             SIGP_CC_NOT_OPERATIONAL)
 693                                 continue;
 694                         info->core[info->configured].core_id =
 695                                 address >> smp_cpu_mt_shift;
 696                         info->configured++;
 697                 }
 698                 info->combined = info->configured;
 699         }
 700         return info;
 701 }
 702
 703 static int smp_add_present_cpu(int cpu);
 704
 705 static int smp_add_core(struct sclp_core_entry *core, cpumask_t *avail,
 706                         bool configured, bool early)
 707 {
 708         struct pcpu *pcpu;
 709         int cpu, nr, i;
 710         u16 address;
 711
 712         nr = 0;
 713         if (sclp.has_core_type && core->type != boot_core_type)
 714                 return nr;
 715         cpu = cpumask_first(avail);
 716         address = core->core_id << smp_cpu_mt_shift;
 717         for (i = 0; (i <= smp_cpu_mtid) && (cpu < nr_cpu_ids); i++) {
 718                 if (pcpu_find_address(cpu_present_mask, address + i))
 719                         continue;
 720                 pcpu = pcpu_devices + cpu;
 721                 pcpu->address = address + i;
 722                 if (configured)
 723                         pcpu->state = CPU_STATE_CONFIGURED;
 724                 else
 725                         pcpu->state = CPU_STATE_STANDBY;
 726                 smp_cpu_set_polarization(cpu, POLARIZATION_UNKNOWN);
 727                 set_cpu_present(cpu, true);
 728                 if (!early && smp_add_present_cpu(cpu) != 0)
 729                         set_cpu_present(cpu, false);
 730                 else
 731                         nr++;
 732                 cpumask_clear_cpu(cpu, avail);
 733                 cpu = cpumask_next(cpu, avail);
 734         }
 735         return nr;
 736 }
 737
 738 static int __smp_rescan_cpus(struct sclp_core_info *info, bool early)
 739 {
 740         struct sclp_core_entry *core;
 741         static cpumask_t avail;
 742         bool configured;
 743         u16 core_id;
 744         int nr, i;
 745
 746         nr = 0;
 747         cpumask_xor(&avail, cpu_possible_mask, cpu_present_mask);
 748         /*
 749          * Add IPL core first (which got logical CPU number 0) to make sure
 750          * that all SMT threads get subsequent logical CPU numbers.
 751          */
 752         if (early) {
 753                 core_id = pcpu_devices[0].address >> smp_cpu_mt_shift;
 754                 for (i = 0; i < info->configured; i++) {
 755                         core = &info->core[i];
 756                         if (core->core_id == core_id) {
 757                                 nr += smp_add_core(core, &avail, true, early);
 758                                 break;
 759                         }
 760                 }
 761         }
 762         for (i = 0; i < info->combined; i++) {
 763                 configured = i < info->configured;
 764                 nr += smp_add_core(&info->core[i], &avail, configured, early);
 765         }
 766         return nr;
 767 }
 768
 769 static void __init smp_detect_cpus(void)
 770 {
 771         unsigned int cpu, mtid, c_cpus, s_cpus;
 772         struct sclp_core_info *info;
 773         u16 address;
 774
 775         /* Get CPU information */
 776         info = smp_get_core_info();
 777         if (!info)
 778                 panic("smp_detect_cpus failed to allocate memory\n");
 779
 780         /* Find boot CPU type */
 781         if (sclp.has_core_type) {
 782                 address = stap();
 783                 for (cpu = 0; cpu < info->combined; cpu++)
 784                         if (info->core[cpu].core_id == address) {
 785                                 /* The boot cpu dictates the cpu type. */
 786                                 boot_core_type = info->core[cpu].type;
 787                                 break;
 788                         }
 789                 if (cpu >= info->combined)
 790                         panic("Could not find boot CPU type");
 791         }
 792
 793         /* Set multi-threading state for the current system */
 794         mtid = boot_core_type ? sclp.mtid : sclp.mtid_cp;
 795         mtid = (mtid < smp_max_threads) ? mtid : smp_max_threads - 1;
 796         pcpu_set_smt(mtid);
 797
 798         /* Print number of CPUs */
 799         c_cpus = s_cpus = 0;
 800         for (cpu = 0; cpu < info->combined; cpu++) {
 801                 if (sclp.has_core_type &&
 802                     info->core[cpu].type != boot_core_type)
 803                         continue;
 804                 if (cpu < info->configured)
 805                         c_cpus += smp_cpu_mtid + 1;
 806                 else
 807                         s_cpus += smp_cpu_mtid + 1;
 808         }
 809         pr_info("%d configured CPUs, %d standby CPUs\n", c_cpus, s_cpus);
 810
 811         /* Add CPUs present at boot */
 812         get_online_cpus();
 813         __smp_rescan_cpus(info, true);
 814         put_online_cpus();
 815         kfree(info);
 816 }
 817
 818 /*
 819  *      Activate a secondary processor.
 820  */
 821 static void smp_start_secondary(void *cpuvoid)
 822 {
 823         S390_lowcore.last_update_clock = get_tod_clock();
 824         S390_lowcore.restart_stack = (unsigned long) restart_stack;
 825         S390_lowcore.restart_fn = (unsigned long) do_restart;
 826         S390_lowcore.restart_data = 0;
 827         S390_lowcore.restart_source = -1UL;
 828         restore_access_regs(S390_lowcore.access_regs_save_area);
 829         __ctl_load(S390_lowcore.cregs_save_area, 0, 15);
 830         __load_psw_mask(PSW_KERNEL_BITS | PSW_MASK_DAT);
 831         cpu_init();
 832         preempt_disable();
 833         init_cpu_timer();
 834         vtime_init();
 835         pfault_init();
 836         notify_cpu_starting(smp_processor_id());
 837         set_cpu_online(smp_processor_id(), true);
 838         inc_irq_stat(CPU_RST);
 839         local_irq_enable();
 840         cpu_startup_entry(CPUHP_ONLINE);
 841 }
 842
 843 /* Upping and downing of CPUs */
 844 int __cpu_up(unsigned int cpu, struct task_struct *tidle)
 845 {
 846         struct pcpu *pcpu;
 847         int base, i, rc;
 848
 849         pcpu = pcpu_devices + cpu;
 850         if (pcpu->state != CPU_STATE_CONFIGURED)
 851                 return -EIO;
 852         base = cpu - (cpu % (smp_cpu_mtid + 1));
 853         for (i = 0; i <= smp_cpu_mtid; i++) {
 854                 if (base + i < nr_cpu_ids)
 855                         if (cpu_online(base + i))
 856                                 break;
 857         }
 858         /*
 859          * If this is the first CPU of the core to get online
 860          * do an initial CPU reset.
 861          */
 862         if (i > smp_cpu_mtid &&
 863             pcpu_sigp_retry(pcpu_devices + base, SIGP_INITIAL_CPU_RESET, 0) !=
 864             SIGP_CC_ORDER_CODE_ACCEPTED)
 865                 return -EIO;
 866
 867         rc = pcpu_alloc_lowcore(pcpu, cpu);
 868         if (rc)
 869                 return rc;
 870         pcpu_prepare_secondary(pcpu, cpu);
 871         pcpu_attach_task(pcpu, tidle);
 872         pcpu_start_fn(pcpu, smp_start_secondary, NULL);
 873         /* Wait until cpu puts itself in the online & active maps */
 874         while (!cpu_online(cpu) || !cpu_active(cpu))
 875                 cpu_relax();
 876         return 0;
 877 }
 878
 879 static unsigned int setup_possible_cpus __initdata;
 880
 881 static int __init _setup_possible_cpus(char *s)
 882 {
 883         get_option(&s, &setup_possible_cpus);
 884         return 0;
 885 }
 886 early_param("possible_cpus", _setup_possible_cpus);
 887
 888 #ifdef CONFIG_HOTPLUG_CPU
 889
 890 int __cpu_disable(void)
 891 {
 892         unsigned long cregs[16];
 893
 894         /* Handle possible pending IPIs */
 895         smp_handle_ext_call();
 896         set_cpu_online(smp_processor_id(), false);
 897         /* Disable pseudo page faults on this cpu. */
 898         pfault_fini();
 899         /* Disable interrupt sources via control register. */
 900         __ctl_store(cregs, 0, 15);
 901         cregs[0]  &= ~0x0000ee70UL;     /* disable all external interrupts */
 902         cregs[6]  &= ~0xff000000UL;     /* disable all I/O interrupts */
 903         cregs[14] &= ~0x1f000000UL;     /* disable most machine checks */
 904         __ctl_load(cregs, 0, 15);
 905         clear_cpu_flag(CIF_NOHZ_DELAY);
 906         return 0;
 907 }
 908
 909 void __cpu_die(unsigned int cpu)
 910 {
 911         struct pcpu *pcpu;
 912
 913         /* Wait until target cpu is down */
 914         pcpu = pcpu_devices + cpu;
 915         while (!pcpu_stopped(pcpu))
 916                 cpu_relax();
 917         pcpu_free_lowcore(pcpu);
 918         atomic_dec(&init_mm.context.attach_count);
 919         cpumask_clear_cpu(cpu, mm_cpumask(&init_mm));
 920         if (MACHINE_HAS_TLB_LC)
 921                 cpumask_clear_cpu(cpu, &init_mm.context.cpu_attach_mask);
 922 }
 923
 924 void __noreturn cpu_die(void)
 925 {
 926         idle_task_exit();
 927         __bpon();
 928         pcpu_sigp_retry(pcpu_devices + smp_processor_id(), SIGP_STOP, 0);
 929         for (;;) ;
 930 }
 931
 932 #endif /* CONFIG_HOTPLUG_CPU */
 933
 934 void __init smp_fill_possible_mask(void)
 935 {
 936         unsigned int possible, sclp_max, cpu;
 937
 938         sclp_max = max(sclp.mtid, sclp.mtid_cp) + 1;
 939         sclp_max = min(smp_max_threads, sclp_max);
 940         sclp_max = sclp.max_cores * sclp_max ?: nr_cpu_ids;
 941         possible = setup_possible_cpus ?: nr_cpu_ids;
 942         possible = min(possible, sclp_max);
 943         for (cpu = 0; cpu < possible && cpu < nr_cpu_ids; cpu++)
 944                 set_cpu_possible(cpu, true);
 945 }
 946
 947 void __init smp_prepare_cpus(unsigned int max_cpus)
 948 {
 949         /* request the 0x1201 emergency signal external interrupt */
 950         if (register_external_irq(EXT_IRQ_EMERGENCY_SIG, do_ext_call_interrupt))
 951                 panic("Couldn't request external interrupt 0x1201");
 952         /* request the 0x1202 external call external interrupt */
 953         if (register_external_irq(EXT_IRQ_EXTERNAL_CALL, do_ext_call_interrupt))
 954                 panic("Couldn't request external interrupt 0x1202");
 955         smp_detect_cpus();
 956 }
 957
 958 void __init smp_prepare_boot_cpu(void)
 959 {
 960         struct pcpu *pcpu = pcpu_devices;
 961
 962         pcpu->state = CPU_STATE_CONFIGURED;
 963         pcpu->address = stap();
 964         pcpu->lowcore = (struct _lowcore *)(unsigned long) store_prefix();
 965         S390_lowcore.percpu_offset = __per_cpu_offset[0];
 966         smp_cpu_set_polarization(0, POLARIZATION_UNKNOWN);
 967         set_cpu_present(0, true);
 968         set_cpu_online(0, true);
 969 }
 970
 971 void __init smp_cpus_done(unsigned int max_cpus)
 972 {
 973 }
 974
 975 void __init smp_setup_processor_id(void)
 976 {
 977         S390_lowcore.cpu_nr = 0;
 978         S390_lowcore.spinlock_lockval = arch_spin_lockval(0);
 979 }
 980
 981 /*
 982  * the frequency of the profiling timer can be changed
 983  * by writing a multiplier value into /proc/profile.
 984  *
 985  * usually you want to run this on all CPUs ;)
 986  */
 987 int setup_profiling_timer(unsigned int multiplier)
 988 {
 989         return 0;
 990 }
 991
 992 #ifdef CONFIG_HOTPLUG_CPU
 993 static ssize_t cpu_configure_show(struct device *dev,
 994                                   struct device_attribute *attr, char *buf)
 995 {
 996         ssize_t count;
 997
 998         mutex_lock(&smp_cpu_state_mutex);
 999         count = sprintf(buf, "%d\n", pcpu_devices[dev->id].state);
1000         mutex_unlock(&smp_cpu_state_mutex);
1001         return count;
1002 }
1003
1004 static ssize_t cpu_configure_store(struct device *dev,
1005                                    struct device_attribute *attr,
1006                                    const char *buf, size_t count)
1007 {
1008         struct pcpu *pcpu;
1009         int cpu, val, rc, i;
1010         char delim;
1011
1012         if (sscanf(buf, "%d %c", &val, &delim) != 1)
1013                 return -EINVAL;
1014         if (val != 0 && val != 1)
1015                 return -EINVAL;
1016         get_online_cpus();
1017         mutex_lock(&smp_cpu_state_mutex);
1018         rc = -EBUSY;
1019         /* disallow configuration changes of online cpus and cpu 0 */
1020         cpu = dev->id;
1021         cpu -= cpu % (smp_cpu_mtid + 1);
1022         if (cpu == 0)
1023                 goto out;
1024         for (i = 0; i <= smp_cpu_mtid; i++)
1025                 if (cpu_online(cpu + i))
1026                         goto out;
1027         pcpu = pcpu_devices + cpu;
1028         rc = 0;
1029         switch (val) {
1030         case 0:
1031                 if (pcpu->state != CPU_STATE_CONFIGURED)
1032                         break;
1033                 rc = sclp_core_deconfigure(pcpu->address >> smp_cpu_mt_shift);
1034                 if (rc)
1035                         break;
1036                 for (i = 0; i <= smp_cpu_mtid; i++) {
1037                         if (cpu + i >= nr_cpu_ids || !cpu_present(cpu + i))
1038                                 continue;
1039                         pcpu[i].state = CPU_STATE_STANDBY;
1040                         smp_cpu_set_polarization(cpu + i,
1041                                                  POLARIZATION_UNKNOWN);
1042                 }
1043                 topology_expect_change();
1044                 break;
1045         case 1:
1046                 if (pcpu->state != CPU_STATE_STANDBY)
1047                         break;
1048                 rc = sclp_core_configure(pcpu->address >> smp_cpu_mt_shift);
1049                 if (rc)
1050                         break;
1051                 for (i = 0; i <= smp_cpu_mtid; i++) {
1052                         if (cpu + i >= nr_cpu_ids || !cpu_present(cpu + i))
1053                                 continue;
1054                         pcpu[i].state = CPU_STATE_CONFIGURED;
1055                         smp_cpu_set_polarization(cpu + i,
1056                                                  POLARIZATION_UNKNOWN);
1057                 }
1058                 topology_expect_change();
1059                 break;
1060         default:
1061                 break;
1062         }
1063 out:
1064         mutex_unlock(&smp_cpu_state_mutex);
1065         put_online_cpus();
1066         return rc ? rc : count;
1067 }
1068 static DEVICE_ATTR(configure, 0644, cpu_configure_show, cpu_configure_store);
1069 #endif /* CONFIG_HOTPLUG_CPU */
1070
1071 static ssize_t show_cpu_address(struct device *dev,
1072                                 struct device_attribute *attr, char *buf)
1073 {
1074         return sprintf(buf, "%d\n", pcpu_devices[dev->id].address);
1075 }
1076 static DEVICE_ATTR(address, 0444, show_cpu_address, NULL);
1077
1078 static struct attribute *cpu_common_attrs[] = {
1079 #ifdef CONFIG_HOTPLUG_CPU
1080         &dev_attr_configure.attr,
1081 #endif
1082         &dev_attr_address.attr,
1083         NULL,
1084 };
1085
1086 static struct attribute_group cpu_common_attr_group = {
1087         .attrs = cpu_common_attrs,
1088 };
1089
1090 static struct attribute *cpu_online_attrs[] = {
1091         &dev_attr_idle_count.attr,
1092         &dev_attr_idle_time_us.attr,
1093         NULL,
1094 };
1095
1096 static struct attribute_group cpu_online_attr_group = {
1097         .attrs = cpu_online_attrs,
1098 };
1099
1100 static int smp_cpu_notify(struct notifier_block *self, unsigned long action,
1101                           void *hcpu)
1102 {
1103         unsigned int cpu = (unsigned int)(long)hcpu;
1104         struct device *s = &per_cpu(cpu_device, cpu)->dev;
1105         int err = 0;
1106
1107         switch (action & ~CPU_TASKS_FROZEN) {
1108         case CPU_ONLINE:
1109                 err = sysfs_create_group(&s->kobj, &cpu_online_attr_group);
1110                 break;
1111         case CPU_DEAD:
1112                 sysfs_remove_group(&s->kobj, &cpu_online_attr_group);
1113                 break;
1114         }
1115         return notifier_from_errno(err);
1116 }
1117
1118 static int smp_add_present_cpu(int cpu)
1119 {
1120         struct device *s;
1121         struct cpu *c;
1122         int rc;
1123
1124         c = kzalloc(sizeof(*c), GFP_KERNEL);
1125         if (!c)
1126                 return -ENOMEM;
1127         per_cpu(cpu_device, cpu) = c;
1128         s = &c->dev;
1129         c->hotpluggable = 1;
1130         rc = register_cpu(c, cpu);
1131         if (rc)
1132                 goto out;
1133         rc = sysfs_create_group(&s->kobj, &cpu_common_attr_group);
1134         if (rc)
1135                 goto out_cpu;
1136         if (cpu_online(cpu)) {
1137                 rc = sysfs_create_group(&s->kobj, &cpu_online_attr_group);
1138                 if (rc)
1139                         goto out_online;
1140         }
1141         rc = topology_cpu_init(c);
1142         if (rc)
1143                 goto out_topology;
1144         return 0;
1145
1146 out_topology:
1147         if (cpu_online(cpu))
1148                 sysfs_remove_group(&s->kobj, &cpu_online_attr_group);
1149 out_online:
1150         sysfs_remove_group(&s->kobj, &cpu_common_attr_group);
1151 out_cpu:
1152 #ifdef CONFIG_HOTPLUG_CPU
1153         unregister_cpu(c);
1154 #endif
1155 out:
1156         return rc;
1157 }
1158
1159 #ifdef CONFIG_HOTPLUG_CPU
1160
1161 int __ref smp_rescan_cpus(void)
1162 {
1163         struct sclp_core_info *info;
1164         int nr;
1165
1166         info = smp_get_core_info();
1167         if (!info)
1168                 return -ENOMEM;
1169         get_online_cpus();
1170         mutex_lock(&smp_cpu_state_mutex);
1171         nr = __smp_rescan_cpus(info, false);
1172         mutex_unlock(&smp_cpu_state_mutex);
1173         put_online_cpus();
1174         kfree(info);
1175         if (nr)
1176                 topology_schedule_update();
1177         return 0;
1178 }
1179
1180 static ssize_t __ref rescan_store(struct device *dev,
1181                                   struct device_attribute *attr,
1182                                   const char *buf,
1183                                   size_t count)
1184 {
1185         int rc;
1186
1187         rc = lock_device_hotplug_sysfs();
1188         if (rc)
1189                 return rc;
1190         rc = smp_rescan_cpus();
1191         unlock_device_hotplug();
1192         return rc ? rc : count;
1193 }
1194 static DEVICE_ATTR(rescan, 0200, NULL, rescan_store);
1195 #endif /* CONFIG_HOTPLUG_CPU */
1196
1197 static int __init s390_smp_init(void)
1198 {
1199         int cpu, rc = 0;
1200
1201 #ifdef CONFIG_HOTPLUG_CPU
1202         rc = device_create_file(cpu_subsys.dev_root, &dev_attr_rescan);
1203         if (rc)
1204                 return rc;
1205 #endif
1206         cpu_notifier_register_begin();
1207         for_each_present_cpu(cpu) {
1208                 rc = smp_add_present_cpu(cpu);
1209                 if (rc)
1210                         goto out;
1211         }
1212
1213         __hotcpu_notifier(smp_cpu_notify, 0);
1214
1215 out:
1216         cpu_notifier_register_done();
1217         return rc;
1218 }
1219 subsys_initcall(s390_smp_init);