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/bootmem.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/kmemleak.h>
  31 #include <linux/delay.h>
  32 #include <linux/interrupt.h>
  33 #include <linux/irqflags.h>
  34 #include <linux/cpu.h>
  35 #include <linux/slab.h>
  36 #include <linux/sched/hotplug.h>
  37 #include <linux/sched/task_stack.h>
  38 #include <linux/crash_dump.h>
  39 #include <linux/memblock.h>
  40 #include <asm/asm-offsets.h>
  41 #include <asm/diag.h>
  42 #include <asm/switch_to.h>
  43 #include <asm/facility.h>
  44 #include <asm/ipl.h>
  45 #include <asm/setup.h>
  46 #include <asm/irq.h>
  47 #include <asm/tlbflush.h>
  48 #include <asm/vtimer.h>
  49 #include <asm/lowcore.h>
  50 #include <asm/sclp.h>
  51 #include <asm/vdso.h>
  52 #include <asm/debug.h>
  53 #include <asm/os_info.h>
  54 #include <asm/sigp.h>
  55 #include <asm/idle.h>
  56 #include <asm/nmi.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 static struct kmem_cache *pcpu_mcesa_cache;
  86
  87 unsigned int smp_cpu_mt_shift;
  88 EXPORT_SYMBOL(smp_cpu_mt_shift);
  89
  90 unsigned int smp_cpu_mtid;
  91 EXPORT_SYMBOL(smp_cpu_mtid);
  92
  93 #ifdef CONFIG_CRASH_DUMP
  94 __vector128 __initdata boot_cpu_vector_save_area[__NUM_VXRS];
  95 #endif
  96
  97 static unsigned int smp_max_threads __initdata = -1U;
  98
  99 static int __init early_nosmt(char *s)
 100 {
 101         smp_max_threads = 1;
 102         return 0;
 103 }
 104 early_param("nosmt", early_nosmt);
 105
 106 static int __init early_smt(char *s)
 107 {
 108         get_option(&s, &smp_max_threads);
 109         return 0;
 110 }
 111 early_param("smt", early_smt);
 112
 113 /*
 114  * The smp_cpu_state_mutex must be held when changing the state or polarization
 115  * member of a pcpu data structure within the pcpu_devices arreay.
 116  */
 117 DEFINE_MUTEX(smp_cpu_state_mutex);
 118
 119 /*
 120  * Signal processor helper functions.
 121  */
 122 static inline int __pcpu_sigp_relax(u16 addr, u8 order, unsigned long parm)
 123 {
 124         int cc;
 125
 126         while (1) {
 127                 cc = __pcpu_sigp(addr, order, parm, NULL);
 128                 if (cc != SIGP_CC_BUSY)
 129                         return cc;
 130                 cpu_relax();
 131         }
 132 }
 133
 134 static int pcpu_sigp_retry(struct pcpu *pcpu, u8 order, u32 parm)
 135 {
 136         int cc, retry;
 137
 138         for (retry = 0; ; retry++) {
 139                 cc = __pcpu_sigp(pcpu->address, order, parm, NULL);
 140                 if (cc != SIGP_CC_BUSY)
 141                         break;
 142                 if (retry >= 3)
 143                         udelay(10);
 144         }
 145         return cc;
 146 }
 147
 148 static inline int pcpu_stopped(struct pcpu *pcpu)
 149 {
 150         u32 uninitialized_var(status);
 151
 152         if (__pcpu_sigp(pcpu->address, SIGP_SENSE,
 153                         0, &status) != SIGP_CC_STATUS_STORED)
 154                 return 0;
 155         return !!(status & (SIGP_STATUS_CHECK_STOP|SIGP_STATUS_STOPPED));
 156 }
 157
 158 static inline int pcpu_running(struct pcpu *pcpu)
 159 {
 160         if (__pcpu_sigp(pcpu->address, SIGP_SENSE_RUNNING,
 161                         0, NULL) != SIGP_CC_STATUS_STORED)
 162                 return 1;
 163         /* Status stored condition code is equivalent to cpu not running. */
 164         return 0;
 165 }
 166
 167 /*
 168  * Find struct pcpu by cpu address.
 169  */
 170 static struct pcpu *pcpu_find_address(const struct cpumask *mask, u16 address)
 171 {
 172         int cpu;
 173
 174         for_each_cpu(cpu, mask)
 175                 if (pcpu_devices[cpu].address == address)
 176                         return pcpu_devices + cpu;
 177         return NULL;
 178 }
 179
 180 static void pcpu_ec_call(struct pcpu *pcpu, int ec_bit)
 181 {
 182         int order;
 183
 184         if (test_and_set_bit(ec_bit, &pcpu->ec_mask))
 185                 return;
 186         order = pcpu_running(pcpu) ? SIGP_EXTERNAL_CALL : SIGP_EMERGENCY_SIGNAL;
 187         pcpu->ec_clk = get_tod_clock_fast();
 188         pcpu_sigp_retry(pcpu, order, 0);
 189 }
 190
 191 #define ASYNC_FRAME_OFFSET (ASYNC_SIZE - STACK_FRAME_OVERHEAD - __PT_SIZE)
 192 #define PANIC_FRAME_OFFSET (PAGE_SIZE - STACK_FRAME_OVERHEAD - __PT_SIZE)
 193
 194 static int pcpu_alloc_lowcore(struct pcpu *pcpu, int cpu)
 195 {
 196         unsigned long async_stack, panic_stack;
 197         unsigned long mcesa_origin, mcesa_bits;
 198         struct lowcore *lc;
 199
 200         mcesa_origin = mcesa_bits = 0;
 201         if (pcpu != &pcpu_devices[0]) {
 202                 pcpu->lowcore = (struct lowcore *)
 203                         __get_free_pages(GFP_KERNEL | GFP_DMA, LC_ORDER);
 204                 async_stack = __get_free_pages(GFP_KERNEL, ASYNC_ORDER);
 205                 panic_stack = __get_free_page(GFP_KERNEL);
 206                 if (!pcpu->lowcore || !panic_stack || !async_stack)
 207                         goto out;
 208                 if (MACHINE_HAS_VX || MACHINE_HAS_GS) {
 209                         mcesa_origin = (unsigned long)
 210                                 kmem_cache_alloc(pcpu_mcesa_cache, GFP_KERNEL);
 211                         if (!mcesa_origin)
 212                                 goto out;
 213                         /* The pointer is stored with mcesa_bits ORed in */
 214                         kmemleak_not_leak((void *) mcesa_origin);
 215                         mcesa_bits = MACHINE_HAS_GS ? 11 : 0;
 216                 }
 217         } else {
 218                 async_stack = pcpu->lowcore->async_stack - ASYNC_FRAME_OFFSET;
 219                 panic_stack = pcpu->lowcore->panic_stack - PANIC_FRAME_OFFSET;
 220                 mcesa_origin = pcpu->lowcore->mcesad & MCESA_ORIGIN_MASK;
 221                 mcesa_bits = pcpu->lowcore->mcesad & MCESA_LC_MASK;
 222         }
 223         lc = pcpu->lowcore;
 224         memcpy(lc, &S390_lowcore, 512);
 225         memset((char *) lc + 512, 0, sizeof(*lc) - 512);
 226         lc->async_stack = async_stack + ASYNC_FRAME_OFFSET;
 227         lc->panic_stack = panic_stack + PANIC_FRAME_OFFSET;
 228         lc->mcesad = mcesa_origin | mcesa_bits;
 229         lc->cpu_nr = cpu;
 230         lc->spinlock_lockval = arch_spin_lockval(cpu);
 231         lc->br_r1_trampoline = 0x07f1;  /* br %r1 */
 232         if (vdso_alloc_per_cpu(lc))
 233                 goto out;
 234         lowcore_ptr[cpu] = lc;
 235         pcpu_sigp_retry(pcpu, SIGP_SET_PREFIX, (u32)(unsigned long) lc);
 236         return 0;
 237 out:
 238         if (pcpu != &pcpu_devices[0]) {
 239                 if (mcesa_origin)
 240                         kmem_cache_free(pcpu_mcesa_cache,
 241                                         (void *) mcesa_origin);
 242                 free_page(panic_stack);
 243                 free_pages(async_stack, ASYNC_ORDER);
 244                 free_pages((unsigned long) pcpu->lowcore, LC_ORDER);
 245         }
 246         return -ENOMEM;
 247 }
 248
 249 #ifdef CONFIG_HOTPLUG_CPU
 250
 251 static void pcpu_free_lowcore(struct pcpu *pcpu)
 252 {
 253         unsigned long mcesa_origin;
 254
 255         pcpu_sigp_retry(pcpu, SIGP_SET_PREFIX, 0);
 256         lowcore_ptr[pcpu - pcpu_devices] = NULL;
 257         vdso_free_per_cpu(pcpu->lowcore);
 258         if (pcpu == &pcpu_devices[0])
 259                 return;
 260         if (MACHINE_HAS_VX || MACHINE_HAS_GS) {
 261                 mcesa_origin = pcpu->lowcore->mcesad & MCESA_ORIGIN_MASK;
 262                 kmem_cache_free(pcpu_mcesa_cache, (void *) mcesa_origin);
 263         }
 264         free_page(pcpu->lowcore->panic_stack-PANIC_FRAME_OFFSET);
 265         free_pages(pcpu->lowcore->async_stack-ASYNC_FRAME_OFFSET, ASYNC_ORDER);
 266         free_pages((unsigned long) pcpu->lowcore, LC_ORDER);
 267 }
 268
 269 #endif /* CONFIG_HOTPLUG_CPU */
 270
 271 static void pcpu_prepare_secondary(struct pcpu *pcpu, int cpu)
 272 {
 273         struct lowcore *lc = pcpu->lowcore;
 274
 275         cpumask_set_cpu(cpu, &init_mm.context.cpu_attach_mask);
 276         cpumask_set_cpu(cpu, mm_cpumask(&init_mm));
 277         lc->cpu_nr = cpu;
 278         lc->spinlock_lockval = arch_spin_lockval(cpu);
 279         lc->percpu_offset = __per_cpu_offset[cpu];
 280         lc->kernel_asce = S390_lowcore.kernel_asce;
 281         lc->machine_flags = S390_lowcore.machine_flags;
 282         lc->user_timer = lc->system_timer = lc->steal_timer = 0;
 283         __ctl_store(lc->cregs_save_area, 0, 15);
 284         save_access_regs((unsigned int *) lc->access_regs_save_area);
 285         memcpy(lc->stfle_fac_list, S390_lowcore.stfle_fac_list,
 286                sizeof(lc->stfle_fac_list));
 287         memcpy(lc->alt_stfle_fac_list, S390_lowcore.alt_stfle_fac_list,
 288                sizeof(lc->alt_stfle_fac_list));
 289 }
 290
 291 static void pcpu_attach_task(struct pcpu *pcpu, struct task_struct *tsk)
 292 {
 293         struct lowcore *lc = pcpu->lowcore;
 294
 295         lc->kernel_stack = (unsigned long) task_stack_page(tsk)
 296                 + THREAD_SIZE - STACK_FRAME_OVERHEAD - sizeof(struct pt_regs);
 297         lc->current_task = (unsigned long) tsk;
 298         lc->lpp = LPP_MAGIC;
 299         lc->current_pid = tsk->pid;
 300         lc->user_timer = tsk->thread.user_timer;
 301         lc->guest_timer = tsk->thread.guest_timer;
 302         lc->system_timer = tsk->thread.system_timer;
 303         lc->hardirq_timer = tsk->thread.hardirq_timer;
 304         lc->softirq_timer = tsk->thread.softirq_timer;
 305         lc->steal_timer = 0;
 306 }
 307
 308 static void pcpu_start_fn(struct pcpu *pcpu, void (*func)(void *), void *data)
 309 {
 310         struct lowcore *lc = pcpu->lowcore;
 311
 312         lc->restart_stack = lc->kernel_stack;
 313         lc->restart_fn = (unsigned long) func;
 314         lc->restart_data = (unsigned long) data;
 315         lc->restart_source = -1UL;
 316         pcpu_sigp_retry(pcpu, SIGP_RESTART, 0);
 317 }
 318
 319 /*
 320  * Call function via PSW restart on pcpu and stop the current cpu.
 321  */
 322 static void pcpu_delegate(struct pcpu *pcpu, void (*func)(void *),
 323                           void *data, unsigned long stack)
 324 {
 325         struct lowcore *lc = lowcore_ptr[pcpu - pcpu_devices];
 326         unsigned long source_cpu = stap();
 327
 328         __load_psw_mask(PSW_KERNEL_BITS);
 329         if (pcpu->address == source_cpu)
 330                 func(data);     /* should not return */
 331         /* Stop target cpu (if func returns this stops the current cpu). */
 332         pcpu_sigp_retry(pcpu, SIGP_STOP, 0);
 333         /* Restart func on the target cpu and stop the current cpu. */
 334         mem_assign_absolute(lc->restart_stack, stack);
 335         mem_assign_absolute(lc->restart_fn, (unsigned long) func);
 336         mem_assign_absolute(lc->restart_data, (unsigned long) data);
 337         mem_assign_absolute(lc->restart_source, source_cpu);
 338         __bpon();
 339         asm volatile(
 340                 "0:     sigp    0,%0,%2 # sigp restart to target cpu\n"
 341                 "       brc     2,0b    # busy, try again\n"
 342                 "1:     sigp    0,%1,%3 # sigp stop to current cpu\n"
 343                 "       brc     2,1b    # busy, try again\n"
 344                 : : "d" (pcpu->address), "d" (source_cpu),
 345                     "K" (SIGP_RESTART), "K" (SIGP_STOP)
 346                 : "0", "1", "cc");
 347         for (;;) ;
 348 }
 349
 350 /*
 351  * Enable additional logical cpus for multi-threading.
 352  */
 353 static int pcpu_set_smt(unsigned int mtid)
 354 {
 355         int cc;
 356
 357         if (smp_cpu_mtid == mtid)
 358                 return 0;
 359         cc = __pcpu_sigp(0, SIGP_SET_MULTI_THREADING, mtid, NULL);
 360         if (cc == 0) {
 361                 smp_cpu_mtid = mtid;
 362                 smp_cpu_mt_shift = 0;
 363                 while (smp_cpu_mtid >= (1U << smp_cpu_mt_shift))
 364                         smp_cpu_mt_shift++;
 365                 pcpu_devices[0].address = stap();
 366         }
 367         return cc;
 368 }
 369
 370 /*
 371  * Call function on an online CPU.
 372  */
 373 void smp_call_online_cpu(void (*func)(void *), void *data)
 374 {
 375         struct pcpu *pcpu;
 376
 377         /* Use the current cpu if it is online. */
 378         pcpu = pcpu_find_address(cpu_online_mask, stap());
 379         if (!pcpu)
 380                 /* Use the first online cpu. */
 381                 pcpu = pcpu_devices + cpumask_first(cpu_online_mask);
 382         pcpu_delegate(pcpu, func, data, (unsigned long) restart_stack);
 383 }
 384
 385 /*
 386  * Call function on the ipl CPU.
 387  */
 388 void smp_call_ipl_cpu(void (*func)(void *), void *data)
 389 {
 390         struct lowcore *lc = pcpu_devices->lowcore;
 391
 392         if (pcpu_devices[0].address == stap())
 393                 lc = &S390_lowcore;
 394
 395         pcpu_delegate(&pcpu_devices[0], func, data,
 396                       lc->panic_stack - PANIC_FRAME_OFFSET + PAGE_SIZE);
 397 }
 398
 399 int smp_find_processor_id(u16 address)
 400 {
 401         int cpu;
 402
 403         for_each_present_cpu(cpu)
 404                 if (pcpu_devices[cpu].address == address)
 405                         return cpu;
 406         return -1;
 407 }
 408
 409 bool notrace arch_vcpu_is_preempted(int cpu)
 410 {
 411         if (test_cpu_flag_of(CIF_ENABLED_WAIT, cpu))
 412                 return false;
 413         if (pcpu_running(pcpu_devices + cpu))
 414                 return false;
 415         return true;
 416 }
 417 EXPORT_SYMBOL(arch_vcpu_is_preempted);
 418
 419 void notrace smp_yield_cpu(int cpu)
 420 {
 421         if (MACHINE_HAS_DIAG9C) {
 422                 diag_stat_inc_norecursion(DIAG_STAT_X09C);
 423                 asm volatile("diag %0,0,0x9c"
 424                              : : "d" (pcpu_devices[cpu].address));
 425         } else if (MACHINE_HAS_DIAG44) {
 426                 diag_stat_inc_norecursion(DIAG_STAT_X044);
 427                 asm volatile("diag 0,0,0x44");
 428         }
 429 }
 430
 431 /*
 432  * Send cpus emergency shutdown signal. This gives the cpus the
 433  * opportunity to complete outstanding interrupts.
 434  */
 435 static void smp_emergency_stop(cpumask_t *cpumask)
 436 {
 437         u64 end;
 438         int cpu;
 439
 440         end = get_tod_clock() + (1000000UL << 12);
 441         for_each_cpu(cpu, cpumask) {
 442                 struct pcpu *pcpu = pcpu_devices + cpu;
 443                 set_bit(ec_stop_cpu, &pcpu->ec_mask);
 444                 while (__pcpu_sigp(pcpu->address, SIGP_EMERGENCY_SIGNAL,
 445                                    0, NULL) == SIGP_CC_BUSY &&
 446                        get_tod_clock() < end)
 447                         cpu_relax();
 448         }
 449         while (get_tod_clock() < end) {
 450                 for_each_cpu(cpu, cpumask)
 451                         if (pcpu_stopped(pcpu_devices + cpu))
 452                                 cpumask_clear_cpu(cpu, cpumask);
 453                 if (cpumask_empty(cpumask))
 454                         break;
 455                 cpu_relax();
 456         }
 457 }
 458
 459 /*
 460  * Stop all cpus but the current one.
 461  */
 462 void smp_send_stop(void)
 463 {
 464         cpumask_t cpumask;
 465         int cpu;
 466
 467         /* Disable all interrupts/machine checks */
 468         __load_psw_mask(PSW_KERNEL_BITS | PSW_MASK_DAT);
 469         trace_hardirqs_off();
 470
 471         debug_set_critical();
 472         cpumask_copy(&cpumask, cpu_online_mask);
 473         cpumask_clear_cpu(smp_processor_id(), &cpumask);
 474
 475         if (oops_in_progress)
 476                 smp_emergency_stop(&cpumask);
 477
 478         /* stop all processors */
 479         for_each_cpu(cpu, &cpumask) {
 480                 struct pcpu *pcpu = pcpu_devices + cpu;
 481                 pcpu_sigp_retry(pcpu, SIGP_STOP, 0);
 482                 while (!pcpu_stopped(pcpu))
 483                         cpu_relax();
 484         }
 485 }
 486
 487 /*
 488  * This is the main routine where commands issued by other
 489  * cpus are handled.
 490  */
 491 static void smp_handle_ext_call(void)
 492 {
 493         unsigned long bits;
 494
 495         /* handle bit signal external calls */
 496         bits = xchg(&pcpu_devices[smp_processor_id()].ec_mask, 0);
 497         if (test_bit(ec_stop_cpu, &bits))
 498                 smp_stop_cpu();
 499         if (test_bit(ec_schedule, &bits))
 500                 scheduler_ipi();
 501         if (test_bit(ec_call_function_single, &bits))
 502                 generic_smp_call_function_single_interrupt();
 503 }
 504
 505 static void do_ext_call_interrupt(struct ext_code ext_code,
 506                                   unsigned int param32, unsigned long param64)
 507 {
 508         inc_irq_stat(ext_code.code == 0x1202 ? IRQEXT_EXC : IRQEXT_EMS);
 509         smp_handle_ext_call();
 510 }
 511
 512 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
 513 {
 514         int cpu;
 515
 516         for_each_cpu(cpu, mask)
 517                 pcpu_ec_call(pcpu_devices + cpu, ec_call_function_single);
 518 }
 519
 520 void arch_send_call_function_single_ipi(int cpu)
 521 {
 522         pcpu_ec_call(pcpu_devices + cpu, ec_call_function_single);
 523 }
 524
 525 /*
 526  * this function sends a 'reschedule' IPI to another CPU.
 527  * it goes straight through and wastes no time serializing
 528  * anything. Worst case is that we lose a reschedule ...
 529  */
 530 void smp_send_reschedule(int cpu)
 531 {
 532         pcpu_ec_call(pcpu_devices + cpu, ec_schedule);
 533 }
 534
 535 /*
 536  * parameter area for the set/clear control bit callbacks
 537  */
 538 struct ec_creg_mask_parms {
 539         unsigned long orval;
 540         unsigned long andval;
 541         int cr;
 542 };
 543
 544 /*
 545  * callback for setting/clearing control bits
 546  */
 547 static void smp_ctl_bit_callback(void *info)
 548 {
 549         struct ec_creg_mask_parms *pp = info;
 550         unsigned long cregs[16];
 551
 552         __ctl_store(cregs, 0, 15);
 553         cregs[pp->cr] = (cregs[pp->cr] & pp->andval) | pp->orval;
 554         __ctl_load(cregs, 0, 15);
 555 }
 556
 557 /*
 558  * Set a bit in a control register of all cpus
 559  */
 560 void smp_ctl_set_bit(int cr, int bit)
 561 {
 562         struct ec_creg_mask_parms parms = { 1UL << bit, -1UL, cr };
 563
 564         on_each_cpu(smp_ctl_bit_callback, &parms, 1);
 565 }
 566 EXPORT_SYMBOL(smp_ctl_set_bit);
 567
 568 /*
 569  * Clear a bit in a control register of all cpus
 570  */
 571 void smp_ctl_clear_bit(int cr, int bit)
 572 {
 573         struct ec_creg_mask_parms parms = { 0, ~(1UL << bit), cr };
 574
 575         on_each_cpu(smp_ctl_bit_callback, &parms, 1);
 576 }
 577 EXPORT_SYMBOL(smp_ctl_clear_bit);
 578
 579 #ifdef CONFIG_CRASH_DUMP
 580
 581 int smp_store_status(int cpu)
 582 {
 583         struct pcpu *pcpu = pcpu_devices + cpu;
 584         unsigned long pa;
 585
 586         pa = __pa(&pcpu->lowcore->floating_pt_save_area);
 587         if (__pcpu_sigp_relax(pcpu->address, SIGP_STORE_STATUS_AT_ADDRESS,
 588                               pa) != SIGP_CC_ORDER_CODE_ACCEPTED)
 589                 return -EIO;
 590         if (!MACHINE_HAS_VX && !MACHINE_HAS_GS)
 591                 return 0;
 592         pa = __pa(pcpu->lowcore->mcesad & MCESA_ORIGIN_MASK);
 593         if (MACHINE_HAS_GS)
 594                 pa |= pcpu->lowcore->mcesad & MCESA_LC_MASK;
 595         if (__pcpu_sigp_relax(pcpu->address, SIGP_STORE_ADDITIONAL_STATUS,
 596                               pa) != SIGP_CC_ORDER_CODE_ACCEPTED)
 597                 return -EIO;
 598         return 0;
 599 }
 600
 601 /*
 602  * Collect CPU state of the previous, crashed system.
 603  * There are four cases:
 604  * 1) standard zfcp dump
 605  *    condition: OLDMEM_BASE == NULL && ipl_info.type == IPL_TYPE_FCP_DUMP
 606  *    The state for all CPUs except the boot CPU needs to be collected
 607  *    with sigp stop-and-store-status. The boot CPU state is located in
 608  *    the absolute lowcore of the memory stored in the HSA. The zcore code
 609  *    will copy the boot CPU state from the HSA.
 610  * 2) stand-alone kdump for SCSI (zfcp dump with swapped memory)
 611  *    condition: OLDMEM_BASE != NULL && ipl_info.type == IPL_TYPE_FCP_DUMP
 612  *    The state for all CPUs except the boot CPU needs to be collected
 613  *    with sigp stop-and-store-status. The firmware or the boot-loader
 614  *    stored the registers of the boot CPU in the absolute lowcore in the
 615  *    memory of the old system.
 616  * 3) kdump and the old kernel did not store the CPU state,
 617  *    or stand-alone kdump for DASD
 618  *    condition: OLDMEM_BASE != NULL && !is_kdump_kernel()
 619  *    The state for all CPUs except the boot CPU needs to be collected
 620  *    with sigp stop-and-store-status. The kexec code or the boot-loader
 621  *    stored the registers of the boot CPU in the memory of the old system.
 622  * 4) kdump and the old kernel stored the CPU state
 623  *    condition: OLDMEM_BASE != NULL && is_kdump_kernel()
 624  *    This case does not exist for s390 anymore, setup_arch explicitly
 625  *    deactivates the elfcorehdr= kernel parameter
 626  */
 627 static __init void smp_save_cpu_vxrs(struct save_area *sa, u16 addr,
 628                                      bool is_boot_cpu, unsigned long page)
 629 {
 630         __vector128 *vxrs = (__vector128 *) page;
 631
 632         if (is_boot_cpu)
 633                 vxrs = boot_cpu_vector_save_area;
 634         else
 635                 __pcpu_sigp_relax(addr, SIGP_STORE_ADDITIONAL_STATUS, page);
 636         save_area_add_vxrs(sa, vxrs);
 637 }
 638
 639 static __init void smp_save_cpu_regs(struct save_area *sa, u16 addr,
 640                                      bool is_boot_cpu, unsigned long page)
 641 {
 642         void *regs = (void *) page;
 643
 644         if (is_boot_cpu)
 645                 copy_oldmem_kernel(regs, (void *) __LC_FPREGS_SAVE_AREA, 512);
 646         else
 647                 __pcpu_sigp_relax(addr, SIGP_STORE_STATUS_AT_ADDRESS, page);
 648         save_area_add_regs(sa, regs);
 649 }
 650
 651 void __init smp_save_dump_cpus(void)
 652 {
 653         int addr, boot_cpu_addr, max_cpu_addr;
 654         struct save_area *sa;
 655         unsigned long page;
 656         bool is_boot_cpu;
 657
 658         if (!(OLDMEM_BASE || ipl_info.type == IPL_TYPE_FCP_DUMP))
 659                 /* No previous system present, normal boot. */
 660                 return;
 661         /* Allocate a page as dumping area for the store status sigps */
 662         page = memblock_alloc_base(PAGE_SIZE, PAGE_SIZE, 1UL << 31);
 663         /* Set multi-threading state to the previous system. */
 664         pcpu_set_smt(sclp.mtid_prev);
 665         boot_cpu_addr = stap();
 666         max_cpu_addr = SCLP_MAX_CORES << sclp.mtid_prev;
 667         for (addr = 0; addr <= max_cpu_addr; addr++) {
 668                 if (__pcpu_sigp_relax(addr, SIGP_SENSE, 0) ==
 669                     SIGP_CC_NOT_OPERATIONAL)
 670                         continue;
 671                 is_boot_cpu = (addr == boot_cpu_addr);
 672                 /* Allocate save area */
 673                 sa = save_area_alloc(is_boot_cpu);
 674                 if (!sa)
 675                         panic("could not allocate memory for save area\n");
 676                 if (MACHINE_HAS_VX)
 677                         /* Get the vector registers */
 678                         smp_save_cpu_vxrs(sa, addr, is_boot_cpu, page);
 679                 /*
 680                  * For a zfcp dump OLDMEM_BASE == NULL and the registers
 681                  * of the boot CPU are stored in the HSA. To retrieve
 682                  * these registers an SCLP request is required which is
 683                  * done by drivers/s390/char/zcore.c:init_cpu_info()
 684                  */
 685                 if (!is_boot_cpu || OLDMEM_BASE)
 686                         /* Get the CPU registers */
 687                         smp_save_cpu_regs(sa, addr, is_boot_cpu, page);
 688         }
 689         memblock_free(page, PAGE_SIZE);
 690         diag308_reset();
 691         pcpu_set_smt(0);
 692 }
 693 #endif /* CONFIG_CRASH_DUMP */
 694
 695 void smp_cpu_set_polarization(int cpu, int val)
 696 {
 697         pcpu_devices[cpu].polarization = val;
 698 }
 699
 700 int smp_cpu_get_polarization(int cpu)
 701 {
 702         return pcpu_devices[cpu].polarization;
 703 }
 704
 705 static void __ref smp_get_core_info(struct sclp_core_info *info, int early)
 706 {
 707         static int use_sigp_detection;
 708         int address;
 709
 710         if (use_sigp_detection || sclp_get_core_info(info, early)) {
 711                 use_sigp_detection = 1;
 712                 for (address = 0;
 713                      address < (SCLP_MAX_CORES << smp_cpu_mt_shift);
 714                      address += (1U << smp_cpu_mt_shift)) {
 715                         if (__pcpu_sigp_relax(address, SIGP_SENSE, 0) ==
 716                             SIGP_CC_NOT_OPERATIONAL)
 717                                 continue;
 718                         info->core[info->configured].core_id =
 719                                 address >> smp_cpu_mt_shift;
 720                         info->configured++;
 721                 }
 722                 info->combined = info->configured;
 723         }
 724 }
 725
 726 static int smp_add_present_cpu(int cpu);
 727
 728 static int smp_add_core(struct sclp_core_entry *core, cpumask_t *avail,
 729                         bool configured, bool early)
 730 {
 731         struct pcpu *pcpu;
 732         int cpu, nr, i;
 733         u16 address;
 734
 735         nr = 0;
 736         if (sclp.has_core_type && core->type != boot_core_type)
 737                 return nr;
 738         cpu = cpumask_first(avail);
 739         address = core->core_id << smp_cpu_mt_shift;
 740         for (i = 0; (i <= smp_cpu_mtid) && (cpu < nr_cpu_ids); i++) {
 741                 if (pcpu_find_address(cpu_present_mask, address + i))
 742                         continue;
 743                 pcpu = pcpu_devices + cpu;
 744                 pcpu->address = address + i;
 745                 if (configured)
 746                         pcpu->state = CPU_STATE_CONFIGURED;
 747                 else
 748                         pcpu->state = CPU_STATE_STANDBY;
 749                 smp_cpu_set_polarization(cpu, POLARIZATION_UNKNOWN);
 750                 set_cpu_present(cpu, true);
 751                 if (!early && smp_add_present_cpu(cpu) != 0)
 752                         set_cpu_present(cpu, false);
 753                 else
 754                         nr++;
 755                 cpumask_clear_cpu(cpu, avail);
 756                 cpu = cpumask_next(cpu, avail);
 757         }
 758         return nr;
 759 }
 760
 761 static int __smp_rescan_cpus(struct sclp_core_info *info, bool early)
 762 {
 763         struct sclp_core_entry *core;
 764         static cpumask_t avail;
 765         bool configured;
 766         u16 core_id;
 767         int nr, i;
 768
 769         nr = 0;
 770         cpumask_xor(&avail, cpu_possible_mask, cpu_present_mask);
 771         /*
 772          * Add IPL core first (which got logical CPU number 0) to make sure
 773          * that all SMT threads get subsequent logical CPU numbers.
 774          */
 775         if (early) {
 776                 core_id = pcpu_devices[0].address >> smp_cpu_mt_shift;
 777                 for (i = 0; i < info->configured; i++) {
 778                         core = &info->core[i];
 779                         if (core->core_id == core_id) {
 780                                 nr += smp_add_core(core, &avail, true, early);
 781                                 break;
 782                         }
 783                 }
 784         }
 785         for (i = 0; i < info->combined; i++) {
 786                 configured = i < info->configured;
 787                 nr += smp_add_core(&info->core[i], &avail, configured, early);
 788         }
 789         return nr;
 790 }
 791
 792 void __init smp_detect_cpus(void)
 793 {
 794         unsigned int cpu, mtid, c_cpus, s_cpus;
 795         struct sclp_core_info *info;
 796         u16 address;
 797
 798         /* Get CPU information */
 799         info = memblock_virt_alloc(sizeof(*info), 8);
 800         smp_get_core_info(info, 1);
 801         /* Find boot CPU type */
 802         if (sclp.has_core_type) {
 803                 address = stap();
 804                 for (cpu = 0; cpu < info->combined; cpu++)
 805                         if (info->core[cpu].core_id == address) {
 806                                 /* The boot cpu dictates the cpu type. */
 807                                 boot_core_type = info->core[cpu].type;
 808                                 break;
 809                         }
 810                 if (cpu >= info->combined)
 811                         panic("Could not find boot CPU type");
 812         }
 813
 814         /* Set multi-threading state for the current system */
 815         mtid = boot_core_type ? sclp.mtid : sclp.mtid_cp;
 816         mtid = (mtid < smp_max_threads) ? mtid : smp_max_threads - 1;
 817         pcpu_set_smt(mtid);
 818
 819         /* Print number of CPUs */
 820         c_cpus = s_cpus = 0;
 821         for (cpu = 0; cpu < info->combined; cpu++) {
 822                 if (sclp.has_core_type &&
 823                     info->core[cpu].type != boot_core_type)
 824                         continue;
 825                 if (cpu < info->configured)
 826                         c_cpus += smp_cpu_mtid + 1;
 827                 else
 828                         s_cpus += smp_cpu_mtid + 1;
 829         }
 830         pr_info("%d configured CPUs, %d standby CPUs\n", c_cpus, s_cpus);
 831
 832         /* Add CPUs present at boot */
 833         get_online_cpus();
 834         __smp_rescan_cpus(info, true);
 835         put_online_cpus();
 836         memblock_free_early((unsigned long)info, sizeof(*info));
 837 }
 838
 839 /*
 840  *      Activate a secondary processor.
 841  */
 842 static void smp_start_secondary(void *cpuvoid)
 843 {
 844         S390_lowcore.last_update_clock = get_tod_clock();
 845         S390_lowcore.restart_stack = (unsigned long) restart_stack;
 846         S390_lowcore.restart_fn = (unsigned long) do_restart;
 847         S390_lowcore.restart_data = 0;
 848         S390_lowcore.restart_source = -1UL;
 849         restore_access_regs(S390_lowcore.access_regs_save_area);
 850         __ctl_load(S390_lowcore.cregs_save_area, 0, 15);
 851         __load_psw_mask(PSW_KERNEL_BITS | PSW_MASK_DAT);
 852         cpu_init();
 853         preempt_disable();
 854         init_cpu_timer();
 855         vtime_init();
 856         pfault_init();
 857         notify_cpu_starting(smp_processor_id());
 858         set_cpu_online(smp_processor_id(), true);
 859         inc_irq_stat(CPU_RST);
 860         local_irq_enable();
 861         cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
 862 }
 863
 864 /* Upping and downing of CPUs */
 865 int __cpu_up(unsigned int cpu, struct task_struct *tidle)
 866 {
 867         struct pcpu *pcpu = pcpu_devices + cpu;
 868         int rc;
 869
 870         if (pcpu->state != CPU_STATE_CONFIGURED)
 871                 return -EIO;
 872         if (pcpu_sigp_retry(pcpu, SIGP_INITIAL_CPU_RESET, 0) !=
 873             SIGP_CC_ORDER_CODE_ACCEPTED)
 874                 return -EIO;
 875
 876         rc = pcpu_alloc_lowcore(pcpu, cpu);
 877         if (rc)
 878                 return rc;
 879         pcpu_prepare_secondary(pcpu, cpu);
 880         pcpu_attach_task(pcpu, tidle);
 881         pcpu_start_fn(pcpu, smp_start_secondary, NULL);
 882         /* Wait until cpu puts itself in the online & active maps */
 883         while (!cpu_online(cpu))
 884                 cpu_relax();
 885         return 0;
 886 }
 887
 888 static unsigned int setup_possible_cpus __initdata;
 889
 890 static int __init _setup_possible_cpus(char *s)
 891 {
 892         get_option(&s, &setup_possible_cpus);
 893         return 0;
 894 }
 895 early_param("possible_cpus", _setup_possible_cpus);
 896
 897 #ifdef CONFIG_HOTPLUG_CPU
 898
 899 int __cpu_disable(void)
 900 {
 901         unsigned long cregs[16];
 902
 903         /* Handle possible pending IPIs */
 904         smp_handle_ext_call();
 905         set_cpu_online(smp_processor_id(), false);
 906         /* Disable pseudo page faults on this cpu. */
 907         pfault_fini();
 908         /* Disable interrupt sources via control register. */
 909         __ctl_store(cregs, 0, 15);
 910         cregs[0]  &= ~0x0000ee70UL;     /* disable all external interrupts */
 911         cregs[6]  &= ~0xff000000UL;     /* disable all I/O interrupts */
 912         cregs[14] &= ~0x1f000000UL;     /* disable most machine checks */
 913         __ctl_load(cregs, 0, 15);
 914         clear_cpu_flag(CIF_NOHZ_DELAY);
 915         return 0;
 916 }
 917
 918 void __cpu_die(unsigned int cpu)
 919 {
 920         struct pcpu *pcpu;
 921
 922         /* Wait until target cpu is down */
 923         pcpu = pcpu_devices + cpu;
 924         while (!pcpu_stopped(pcpu))
 925                 cpu_relax();
 926         pcpu_free_lowcore(pcpu);
 927         cpumask_clear_cpu(cpu, mm_cpumask(&init_mm));
 928         cpumask_clear_cpu(cpu, &init_mm.context.cpu_attach_mask);
 929 }
 930
 931 void __noreturn cpu_die(void)
 932 {
 933         idle_task_exit();
 934         __bpon();
 935         pcpu_sigp_retry(pcpu_devices + smp_processor_id(), SIGP_STOP, 0);
 936         for (;;) ;
 937 }
 938
 939 #endif /* CONFIG_HOTPLUG_CPU */
 940
 941 void __init smp_fill_possible_mask(void)
 942 {
 943         unsigned int possible, sclp_max, cpu;
 944
 945         sclp_max = max(sclp.mtid, sclp.mtid_cp) + 1;
 946         sclp_max = min(smp_max_threads, sclp_max);
 947         sclp_max = (sclp.max_cores * sclp_max) ?: nr_cpu_ids;
 948         possible = setup_possible_cpus ?: nr_cpu_ids;
 949         possible = min(possible, sclp_max);
 950         for (cpu = 0; cpu < possible && cpu < nr_cpu_ids; cpu++)
 951                 set_cpu_possible(cpu, true);
 952 }
 953
 954 void __init smp_prepare_cpus(unsigned int max_cpus)
 955 {
 956         unsigned long size;
 957
 958         /* request the 0x1201 emergency signal external interrupt */
 959         if (register_external_irq(EXT_IRQ_EMERGENCY_SIG, do_ext_call_interrupt))
 960                 panic("Couldn't request external interrupt 0x1201");
 961         /* request the 0x1202 external call external interrupt */
 962         if (register_external_irq(EXT_IRQ_EXTERNAL_CALL, do_ext_call_interrupt))
 963                 panic("Couldn't request external interrupt 0x1202");
 964         /* create slab cache for the machine-check-extended-save-areas */
 965         if (MACHINE_HAS_VX || MACHINE_HAS_GS) {
 966                 size = 1UL << (MACHINE_HAS_GS ? 11 : 10);
 967                 pcpu_mcesa_cache = kmem_cache_create("nmi_save_areas",
 968                                                      size, size, 0, NULL);
 969                 if (!pcpu_mcesa_cache)
 970                         panic("Couldn't create nmi save area cache");
 971         }
 972 }
 973
 974 void __init smp_prepare_boot_cpu(void)
 975 {
 976         struct pcpu *pcpu = pcpu_devices;
 977
 978         WARN_ON(!cpu_present(0) || !cpu_online(0));
 979         pcpu->state = CPU_STATE_CONFIGURED;
 980         pcpu->lowcore = (struct lowcore *)(unsigned long) store_prefix();
 981         S390_lowcore.percpu_offset = __per_cpu_offset[0];
 982         smp_cpu_set_polarization(0, POLARIZATION_UNKNOWN);
 983 }
 984
 985 void __init smp_cpus_done(unsigned int max_cpus)
 986 {
 987 }
 988
 989 void __init smp_setup_processor_id(void)
 990 {
 991         pcpu_devices[0].address = stap();
 992         S390_lowcore.cpu_nr = 0;
 993         S390_lowcore.spinlock_lockval = arch_spin_lockval(0);
 994 }
 995
 996 /*
 997  * the frequency of the profiling timer can be changed
 998  * by writing a multiplier value into /proc/profile.
 999  *
1000  * usually you want to run this on all CPUs ;)
1001  */
1002 int setup_profiling_timer(unsigned int multiplier)
1003 {
1004         return 0;
1005 }
1006
1007 #ifdef CONFIG_HOTPLUG_CPU
1008 static ssize_t cpu_configure_show(struct device *dev,
1009                                   struct device_attribute *attr, char *buf)
1010 {
1011         ssize_t count;
1012
1013         mutex_lock(&smp_cpu_state_mutex);
1014         count = sprintf(buf, "%d\n", pcpu_devices[dev->id].state);
1015         mutex_unlock(&smp_cpu_state_mutex);
1016         return count;
1017 }
1018
1019 static ssize_t cpu_configure_store(struct device *dev,
1020                                    struct device_attribute *attr,
1021                                    const char *buf, size_t count)
1022 {
1023         struct pcpu *pcpu;
1024         int cpu, val, rc, i;
1025         char delim;
1026
1027         if (sscanf(buf, "%d %c", &val, &delim) != 1)
1028                 return -EINVAL;
1029         if (val != 0 && val != 1)
1030                 return -EINVAL;
1031         get_online_cpus();
1032         mutex_lock(&smp_cpu_state_mutex);
1033         rc = -EBUSY;
1034         /* disallow configuration changes of online cpus and cpu 0 */
1035         cpu = dev->id;
1036         cpu = smp_get_base_cpu(cpu);
1037         if (cpu == 0)
1038                 goto out;
1039         for (i = 0; i <= smp_cpu_mtid; i++)
1040                 if (cpu_online(cpu + i))
1041                         goto out;
1042         pcpu = pcpu_devices + cpu;
1043         rc = 0;
1044         switch (val) {
1045         case 0:
1046                 if (pcpu->state != CPU_STATE_CONFIGURED)
1047                         break;
1048                 rc = sclp_core_deconfigure(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_STANDBY;
1055                         smp_cpu_set_polarization(cpu + i,
1056                                                  POLARIZATION_UNKNOWN);
1057                 }
1058                 topology_expect_change();
1059                 break;
1060         case 1:
1061                 if (pcpu->state != CPU_STATE_STANDBY)
1062                         break;
1063                 rc = sclp_core_configure(pcpu->address >> smp_cpu_mt_shift);
1064                 if (rc)
1065                         break;
1066                 for (i = 0; i <= smp_cpu_mtid; i++) {
1067                         if (cpu + i >= nr_cpu_ids || !cpu_present(cpu + i))
1068                                 continue;
1069                         pcpu[i].state = CPU_STATE_CONFIGURED;
1070                         smp_cpu_set_polarization(cpu + i,
1071                                                  POLARIZATION_UNKNOWN);
1072                 }
1073                 topology_expect_change();
1074                 break;
1075         default:
1076                 break;
1077         }
1078 out:
1079         mutex_unlock(&smp_cpu_state_mutex);
1080         put_online_cpus();
1081         return rc ? rc : count;
1082 }
1083 static DEVICE_ATTR(configure, 0644, cpu_configure_show, cpu_configure_store);
1084 #endif /* CONFIG_HOTPLUG_CPU */
1085
1086 static ssize_t show_cpu_address(struct device *dev,
1087                                 struct device_attribute *attr, char *buf)
1088 {
1089         return sprintf(buf, "%d\n", pcpu_devices[dev->id].address);
1090 }
1091 static DEVICE_ATTR(address, 0444, show_cpu_address, NULL);
1092
1093 static struct attribute *cpu_common_attrs[] = {
1094 #ifdef CONFIG_HOTPLUG_CPU
1095         &dev_attr_configure.attr,
1096 #endif
1097         &dev_attr_address.attr,
1098         NULL,
1099 };
1100
1101 static struct attribute_group cpu_common_attr_group = {
1102         .attrs = cpu_common_attrs,
1103 };
1104
1105 static struct attribute *cpu_online_attrs[] = {
1106         &dev_attr_idle_count.attr,
1107         &dev_attr_idle_time_us.attr,
1108         NULL,
1109 };
1110
1111 static struct attribute_group cpu_online_attr_group = {
1112         .attrs = cpu_online_attrs,
1113 };
1114
1115 static int smp_cpu_online(unsigned int cpu)
1116 {
1117         struct device *s = &per_cpu(cpu_device, cpu)->dev;
1118
1119         return sysfs_create_group(&s->kobj, &cpu_online_attr_group);
1120 }
1121 static int smp_cpu_pre_down(unsigned int cpu)
1122 {
1123         struct device *s = &per_cpu(cpu_device, cpu)->dev;
1124
1125         sysfs_remove_group(&s->kobj, &cpu_online_attr_group);
1126         return 0;
1127 }
1128
1129 static int smp_add_present_cpu(int cpu)
1130 {
1131         struct device *s;
1132         struct cpu *c;
1133         int rc;
1134
1135         c = kzalloc(sizeof(*c), GFP_KERNEL);
1136         if (!c)
1137                 return -ENOMEM;
1138         per_cpu(cpu_device, cpu) = c;
1139         s = &c->dev;
1140         c->hotpluggable = 1;
1141         rc = register_cpu(c, cpu);
1142         if (rc)
1143                 goto out;
1144         rc = sysfs_create_group(&s->kobj, &cpu_common_attr_group);
1145         if (rc)
1146                 goto out_cpu;
1147         rc = topology_cpu_init(c);
1148         if (rc)
1149                 goto out_topology;
1150         return 0;
1151
1152 out_topology:
1153         sysfs_remove_group(&s->kobj, &cpu_common_attr_group);
1154 out_cpu:
1155 #ifdef CONFIG_HOTPLUG_CPU
1156         unregister_cpu(c);
1157 #endif
1158 out:
1159         return rc;
1160 }
1161
1162 #ifdef CONFIG_HOTPLUG_CPU
1163
1164 int __ref smp_rescan_cpus(void)
1165 {
1166         struct sclp_core_info *info;
1167         int nr;
1168
1169         info = kzalloc(sizeof(*info), GFP_KERNEL);
1170         if (!info)
1171                 return -ENOMEM;
1172         smp_get_core_info(info, 0);
1173         get_online_cpus();
1174         mutex_lock(&smp_cpu_state_mutex);
1175         nr = __smp_rescan_cpus(info, false);
1176         mutex_unlock(&smp_cpu_state_mutex);
1177         put_online_cpus();
1178         kfree(info);
1179         if (nr)
1180                 topology_schedule_update();
1181         return 0;
1182 }
1183
1184 static ssize_t __ref rescan_store(struct device *dev,
1185                                   struct device_attribute *attr,
1186                                   const char *buf,
1187                                   size_t count)
1188 {
1189         int rc;
1190
1191         rc = lock_device_hotplug_sysfs();
1192         if (rc)
1193                 return rc;
1194         rc = smp_rescan_cpus();
1195         unlock_device_hotplug();
1196         return rc ? rc : count;
1197 }
1198 static DEVICE_ATTR(rescan, 0200, NULL, rescan_store);
1199 #endif /* CONFIG_HOTPLUG_CPU */
1200
1201 static int __init s390_smp_init(void)
1202 {
1203         int cpu, rc = 0;
1204
1205 #ifdef CONFIG_HOTPLUG_CPU
1206         rc = device_create_file(cpu_subsys.dev_root, &dev_attr_rescan);
1207         if (rc)
1208                 return rc;
1209 #endif
1210         for_each_present_cpu(cpu) {
1211                 rc = smp_add_present_cpu(cpu);
1212                 if (rc)
1213                         goto out;
1214         }
1215
1216         rc = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "s390/smp:online",
1217                                smp_cpu_online, smp_cpu_pre_down);
1218         rc = rc <= 0 ? rc : 0;
1219 out:
1220         return rc;
1221 }
1222 subsys_initcall(s390_smp_init);