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/irq_work.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/kprobes.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/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 <asm/vdso.h>
  59 #include "entry.h"
  60
  61 enum {
  62         ec_schedule = 0,
  63         ec_call_function_single,
  64         ec_stop_cpu,
  65         ec_mcck_pending,
  66         ec_irq_work,
  67 };
  68
  69 enum {
  70         CPU_STATE_STANDBY,
  71         CPU_STATE_CONFIGURED,
  72 };
  73
  74 static DEFINE_PER_CPU(struct cpu *, cpu_device);
  75
  76 struct pcpu {
  77         struct lowcore *lowcore;        /* lowcore page(s) for the cpu */
  78         unsigned long ec_mask;          /* bit mask for ec_xxx functions */
  79         unsigned long ec_clk;           /* sigp timestamp for ec_xxx */
  80         signed char state;              /* physical cpu state */
  81         signed char polarization;       /* physical polarization */
  82         u16 address;                    /* physical cpu address */
  83 };
  84
  85 static u8 boot_core_type;
  86 static struct pcpu pcpu_devices[NR_CPUS];
  87
  88 unsigned int smp_cpu_mt_shift;
  89 EXPORT_SYMBOL(smp_cpu_mt_shift);
  90
  91 unsigned int smp_cpu_mtid;
  92 EXPORT_SYMBOL(smp_cpu_mtid);
  93
  94 #ifdef CONFIG_CRASH_DUMP
  95 __vector128 __initdata boot_cpu_vector_save_area[__NUM_VXRS];
  96 #endif
  97
  98 static unsigned int smp_max_threads __initdata = -1U;
  99
 100 static int __init early_nosmt(char *s)
 101 {
 102         smp_max_threads = 1;
 103         return 0;
 104 }
 105 early_param("nosmt", early_nosmt);
 106
 107 static int __init early_smt(char *s)
 108 {
 109         get_option(&s, &smp_max_threads);
 110         return 0;
 111 }
 112 early_param("smt", early_smt);
 113
 114 /*
 115  * The smp_cpu_state_mutex must be held when changing the state or polarization
 116  * member of a pcpu data structure within the pcpu_devices arreay.
 117  */
 118 DEFINE_MUTEX(smp_cpu_state_mutex);
 119
 120 /*
 121  * Signal processor helper functions.
 122  */
 123 static inline int __pcpu_sigp_relax(u16 addr, u8 order, unsigned long parm)
 124 {
 125         int cc;
 126
 127         while (1) {
 128                 cc = __pcpu_sigp(addr, order, parm, NULL);
 129                 if (cc != SIGP_CC_BUSY)
 130                         return cc;
 131                 cpu_relax();
 132         }
 133 }
 134
 135 static int pcpu_sigp_retry(struct pcpu *pcpu, u8 order, u32 parm)
 136 {
 137         int cc, retry;
 138
 139         for (retry = 0; ; retry++) {
 140                 cc = __pcpu_sigp(pcpu->address, order, parm, NULL);
 141                 if (cc != SIGP_CC_BUSY)
 142                         break;
 143                 if (retry >= 3)
 144                         udelay(10);
 145         }
 146         return cc;
 147 }
 148
 149 static inline int pcpu_stopped(struct pcpu *pcpu)
 150 {
 151         u32 status;
 152
 153         if (__pcpu_sigp(pcpu->address, SIGP_SENSE,
 154                         0, &status) != SIGP_CC_STATUS_STORED)
 155                 return 0;
 156         return !!(status & (SIGP_STATUS_CHECK_STOP|SIGP_STATUS_STOPPED));
 157 }
 158
 159 static inline int pcpu_running(struct pcpu *pcpu)
 160 {
 161         if (__pcpu_sigp(pcpu->address, SIGP_SENSE_RUNNING,
 162                         0, NULL) != SIGP_CC_STATUS_STORED)
 163                 return 1;
 164         /* Status stored condition code is equivalent to cpu not running. */
 165         return 0;
 166 }
 167
 168 /*
 169  * Find struct pcpu by cpu address.
 170  */
 171 static struct pcpu *pcpu_find_address(const struct cpumask *mask, u16 address)
 172 {
 173         int cpu;
 174
 175         for_each_cpu(cpu, mask)
 176                 if (pcpu_devices[cpu].address == address)
 177                         return pcpu_devices + cpu;
 178         return NULL;
 179 }
 180
 181 static void pcpu_ec_call(struct pcpu *pcpu, int ec_bit)
 182 {
 183         int order;
 184
 185         if (test_and_set_bit(ec_bit, &pcpu->ec_mask))
 186                 return;
 187         order = pcpu_running(pcpu) ? SIGP_EXTERNAL_CALL : SIGP_EMERGENCY_SIGNAL;
 188         pcpu->ec_clk = get_tod_clock_fast();
 189         pcpu_sigp_retry(pcpu, order, 0);
 190 }
 191
 192 static int pcpu_alloc_lowcore(struct pcpu *pcpu, int cpu)
 193 {
 194         unsigned long async_stack, nodat_stack, mcck_stack;
 195         struct lowcore *lc;
 196
 197         if (pcpu != &pcpu_devices[0]) {
 198                 pcpu->lowcore = (struct lowcore *)
 199                         __get_free_pages(GFP_KERNEL | GFP_DMA, LC_ORDER);
 200                 nodat_stack = __get_free_pages(GFP_KERNEL, THREAD_SIZE_ORDER);
 201                 if (!pcpu->lowcore || !nodat_stack)
 202                         goto out;
 203         } else {
 204                 nodat_stack = pcpu->lowcore->nodat_stack - STACK_INIT_OFFSET;
 205         }
 206         async_stack = stack_alloc();
 207         mcck_stack = stack_alloc();
 208         if (!async_stack || !mcck_stack)
 209                 goto out_stack;
 210         lc = pcpu->lowcore;
 211         memcpy(lc, &S390_lowcore, 512);
 212         memset((char *) lc + 512, 0, sizeof(*lc) - 512);
 213         lc->async_stack = async_stack + STACK_INIT_OFFSET;
 214         lc->nodat_stack = nodat_stack + STACK_INIT_OFFSET;
 215         lc->mcck_stack = mcck_stack + STACK_INIT_OFFSET;
 216         lc->cpu_nr = cpu;
 217         lc->spinlock_lockval = arch_spin_lockval(cpu);
 218         lc->spinlock_index = 0;
 219         lc->br_r1_trampoline = 0x07f1;  /* br %r1 */
 220         lc->return_lpswe = gen_lpswe(__LC_RETURN_PSW);
 221         lc->return_mcck_lpswe = gen_lpswe(__LC_RETURN_MCCK_PSW);
 222         if (nmi_alloc_per_cpu(lc))
 223                 goto out_stack;
 224         lowcore_ptr[cpu] = lc;
 225         pcpu_sigp_retry(pcpu, SIGP_SET_PREFIX, (u32)(unsigned long) lc);
 226         return 0;
 227
 228 out_stack:
 229         stack_free(mcck_stack);
 230         stack_free(async_stack);
 231 out:
 232         if (pcpu != &pcpu_devices[0]) {
 233                 free_pages(nodat_stack, THREAD_SIZE_ORDER);
 234                 free_pages((unsigned long) pcpu->lowcore, LC_ORDER);
 235         }
 236         return -ENOMEM;
 237 }
 238
 239 static void pcpu_free_lowcore(struct pcpu *pcpu)
 240 {
 241         unsigned long async_stack, nodat_stack, mcck_stack, lowcore;
 242
 243         nodat_stack = pcpu->lowcore->nodat_stack - STACK_INIT_OFFSET;
 244         async_stack = pcpu->lowcore->async_stack - STACK_INIT_OFFSET;
 245         mcck_stack = pcpu->lowcore->mcck_stack - STACK_INIT_OFFSET;
 246         lowcore = (unsigned long) pcpu->lowcore;
 247
 248         pcpu_sigp_retry(pcpu, SIGP_SET_PREFIX, 0);
 249         lowcore_ptr[pcpu - pcpu_devices] = NULL;
 250         nmi_free_per_cpu(pcpu->lowcore);
 251         stack_free(async_stack);
 252         stack_free(mcck_stack);
 253         if (pcpu == &pcpu_devices[0])
 254                 return;
 255         free_pages(nodat_stack, THREAD_SIZE_ORDER);
 256         free_pages(lowcore, LC_ORDER);
 257 }
 258
 259 static void pcpu_prepare_secondary(struct pcpu *pcpu, int cpu)
 260 {
 261         struct lowcore *lc = pcpu->lowcore;
 262
 263         cpumask_set_cpu(cpu, &init_mm.context.cpu_attach_mask);
 264         cpumask_set_cpu(cpu, mm_cpumask(&init_mm));
 265         lc->cpu_nr = cpu;
 266         lc->spinlock_lockval = arch_spin_lockval(cpu);
 267         lc->spinlock_index = 0;
 268         lc->percpu_offset = __per_cpu_offset[cpu];
 269         lc->kernel_asce = S390_lowcore.kernel_asce;
 270         lc->user_asce = s390_invalid_asce;
 271         lc->machine_flags = S390_lowcore.machine_flags;
 272         lc->user_timer = lc->system_timer =
 273                 lc->steal_timer = lc->avg_steal_timer = 0;
 274         __ctl_store(lc->cregs_save_area, 0, 15);
 275         lc->cregs_save_area[1] = lc->kernel_asce;
 276         lc->cregs_save_area[7] = lc->user_asce;
 277         save_access_regs((unsigned int *) lc->access_regs_save_area);
 278         memcpy(lc->stfle_fac_list, S390_lowcore.stfle_fac_list,
 279                sizeof(lc->stfle_fac_list));
 280         memcpy(lc->alt_stfle_fac_list, S390_lowcore.alt_stfle_fac_list,
 281                sizeof(lc->alt_stfle_fac_list));
 282         arch_spin_lock_setup(cpu);
 283 }
 284
 285 static void pcpu_attach_task(struct pcpu *pcpu, struct task_struct *tsk)
 286 {
 287         struct lowcore *lc = pcpu->lowcore;
 288
 289         lc->kernel_stack = (unsigned long) task_stack_page(tsk)
 290                 + THREAD_SIZE - STACK_FRAME_OVERHEAD - sizeof(struct pt_regs);
 291         lc->current_task = (unsigned long) tsk;
 292         lc->lpp = LPP_MAGIC;
 293         lc->current_pid = tsk->pid;
 294         lc->user_timer = tsk->thread.user_timer;
 295         lc->guest_timer = tsk->thread.guest_timer;
 296         lc->system_timer = tsk->thread.system_timer;
 297         lc->hardirq_timer = tsk->thread.hardirq_timer;
 298         lc->softirq_timer = tsk->thread.softirq_timer;
 299         lc->steal_timer = 0;
 300 }
 301
 302 static void pcpu_start_fn(struct pcpu *pcpu, void (*func)(void *), void *data)
 303 {
 304         struct lowcore *lc = pcpu->lowcore;
 305
 306         lc->restart_stack = lc->nodat_stack;
 307         lc->restart_fn = (unsigned long) func;
 308         lc->restart_data = (unsigned long) data;
 309         lc->restart_source = -1UL;
 310         pcpu_sigp_retry(pcpu, SIGP_RESTART, 0);
 311 }
 312
 313 /*
 314  * Call function via PSW restart on pcpu and stop the current cpu.
 315  */
 316 static void __pcpu_delegate(void (*func)(void*), void *data)
 317 {
 318         func(data);     /* should not return */
 319 }
 320
 321 static void __no_sanitize_address pcpu_delegate(struct pcpu *pcpu,
 322                                                 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 | PSW_MASK_DAT);
 329         if (pcpu->address == source_cpu)
 330                 CALL_ON_STACK(__pcpu_delegate, stack, 2, func, data);
 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->nodat_stack);
 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 void schedule_mcck_handler(void)
 410 {
 411         pcpu_ec_call(pcpu_devices + smp_processor_id(), ec_mcck_pending);
 412 }
 413
 414 bool notrace arch_vcpu_is_preempted(int cpu)
 415 {
 416         if (test_cpu_flag_of(CIF_ENABLED_WAIT, cpu))
 417                 return false;
 418         if (pcpu_running(pcpu_devices + cpu))
 419                 return false;
 420         return true;
 421 }
 422 EXPORT_SYMBOL(arch_vcpu_is_preempted);
 423
 424 void notrace smp_yield_cpu(int cpu)
 425 {
 426         if (!MACHINE_HAS_DIAG9C)
 427                 return;
 428         diag_stat_inc_norecursion(DIAG_STAT_X09C);
 429         asm volatile("diag %0,0,0x9c"
 430                      : : "d" (pcpu_devices[cpu].address));
 431 }
 432 EXPORT_SYMBOL_GPL(smp_yield_cpu);
 433
 434 /*
 435  * Send cpus emergency shutdown signal. This gives the cpus the
 436  * opportunity to complete outstanding interrupts.
 437  */
 438 void notrace smp_emergency_stop(void)
 439 {
 440         static arch_spinlock_t lock = __ARCH_SPIN_LOCK_UNLOCKED;
 441         static cpumask_t cpumask;
 442         u64 end;
 443         int cpu;
 444
 445         arch_spin_lock(&lock);
 446         cpumask_copy(&cpumask, cpu_online_mask);
 447         cpumask_clear_cpu(smp_processor_id(), &cpumask);
 448
 449         end = get_tod_clock() + (1000000UL << 12);
 450         for_each_cpu(cpu, &cpumask) {
 451                 struct pcpu *pcpu = pcpu_devices + cpu;
 452                 set_bit(ec_stop_cpu, &pcpu->ec_mask);
 453                 while (__pcpu_sigp(pcpu->address, SIGP_EMERGENCY_SIGNAL,
 454                                    0, NULL) == SIGP_CC_BUSY &&
 455                        get_tod_clock() < end)
 456                         cpu_relax();
 457         }
 458         while (get_tod_clock() < end) {
 459                 for_each_cpu(cpu, &cpumask)
 460                         if (pcpu_stopped(pcpu_devices + cpu))
 461                                 cpumask_clear_cpu(cpu, &cpumask);
 462                 if (cpumask_empty(&cpumask))
 463                         break;
 464                 cpu_relax();
 465         }
 466         arch_spin_unlock(&lock);
 467 }
 468 NOKPROBE_SYMBOL(smp_emergency_stop);
 469
 470 /*
 471  * Stop all cpus but the current one.
 472  */
 473 void smp_send_stop(void)
 474 {
 475         int cpu;
 476
 477         /* Disable all interrupts/machine checks */
 478         __load_psw_mask(PSW_KERNEL_BITS | PSW_MASK_DAT);
 479         trace_hardirqs_off();
 480
 481         debug_set_critical();
 482
 483         if (oops_in_progress)
 484                 smp_emergency_stop();
 485
 486         /* stop all processors */
 487         for_each_online_cpu(cpu) {
 488                 if (cpu == smp_processor_id())
 489                         continue;
 490                 pcpu_sigp_retry(pcpu_devices + cpu, SIGP_STOP, 0);
 491                 while (!pcpu_stopped(pcpu_devices + cpu))
 492                         cpu_relax();
 493         }
 494 }
 495
 496 /*
 497  * This is the main routine where commands issued by other
 498  * cpus are handled.
 499  */
 500 static void smp_handle_ext_call(void)
 501 {
 502         unsigned long bits;
 503
 504         /* handle bit signal external calls */
 505         bits = xchg(&pcpu_devices[smp_processor_id()].ec_mask, 0);
 506         if (test_bit(ec_stop_cpu, &bits))
 507                 smp_stop_cpu();
 508         if (test_bit(ec_schedule, &bits))
 509                 scheduler_ipi();
 510         if (test_bit(ec_call_function_single, &bits))
 511                 generic_smp_call_function_single_interrupt();
 512         if (test_bit(ec_mcck_pending, &bits))
 513                 __s390_handle_mcck();
 514         if (test_bit(ec_irq_work, &bits))
 515                 irq_work_run();
 516 }
 517
 518 static void do_ext_call_interrupt(struct ext_code ext_code,
 519                                   unsigned int param32, unsigned long param64)
 520 {
 521         inc_irq_stat(ext_code.code == 0x1202 ? IRQEXT_EXC : IRQEXT_EMS);
 522         smp_handle_ext_call();
 523 }
 524
 525 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
 526 {
 527         int cpu;
 528
 529         for_each_cpu(cpu, mask)
 530                 pcpu_ec_call(pcpu_devices + cpu, ec_call_function_single);
 531 }
 532
 533 void arch_send_call_function_single_ipi(int cpu)
 534 {
 535         pcpu_ec_call(pcpu_devices + cpu, ec_call_function_single);
 536 }
 537
 538 /*
 539  * this function sends a 'reschedule' IPI to another CPU.
 540  * it goes straight through and wastes no time serializing
 541  * anything. Worst case is that we lose a reschedule ...
 542  */
 543 void smp_send_reschedule(int cpu)
 544 {
 545         pcpu_ec_call(pcpu_devices + cpu, ec_schedule);
 546 }
 547
 548 #ifdef CONFIG_IRQ_WORK
 549 void arch_irq_work_raise(void)
 550 {
 551         pcpu_ec_call(pcpu_devices + smp_processor_id(), ec_irq_work);
 552 }
 553 #endif
 554
 555 /*
 556  * parameter area for the set/clear control bit callbacks
 557  */
 558 struct ec_creg_mask_parms {
 559         unsigned long orval;
 560         unsigned long andval;
 561         int cr;
 562 };
 563
 564 /*
 565  * callback for setting/clearing control bits
 566  */
 567 static void smp_ctl_bit_callback(void *info)
 568 {
 569         struct ec_creg_mask_parms *pp = info;
 570         unsigned long cregs[16];
 571
 572         __ctl_store(cregs, 0, 15);
 573         cregs[pp->cr] = (cregs[pp->cr] & pp->andval) | pp->orval;
 574         __ctl_load(cregs, 0, 15);
 575 }
 576
 577 /*
 578  * Set a bit in a control register of all cpus
 579  */
 580 void smp_ctl_set_bit(int cr, int bit)
 581 {
 582         struct ec_creg_mask_parms parms = { 1UL << bit, -1UL, cr };
 583
 584         on_each_cpu(smp_ctl_bit_callback, &parms, 1);
 585 }
 586 EXPORT_SYMBOL(smp_ctl_set_bit);
 587
 588 /*
 589  * Clear a bit in a control register of all cpus
 590  */
 591 void smp_ctl_clear_bit(int cr, int bit)
 592 {
 593         struct ec_creg_mask_parms parms = { 0, ~(1UL << bit), cr };
 594
 595         on_each_cpu(smp_ctl_bit_callback, &parms, 1);
 596 }
 597 EXPORT_SYMBOL(smp_ctl_clear_bit);
 598
 599 #ifdef CONFIG_CRASH_DUMP
 600
 601 int smp_store_status(int cpu)
 602 {
 603         struct pcpu *pcpu = pcpu_devices + cpu;
 604         unsigned long pa;
 605
 606         pa = __pa(&pcpu->lowcore->floating_pt_save_area);
 607         if (__pcpu_sigp_relax(pcpu->address, SIGP_STORE_STATUS_AT_ADDRESS,
 608                               pa) != SIGP_CC_ORDER_CODE_ACCEPTED)
 609                 return -EIO;
 610         if (!MACHINE_HAS_VX && !MACHINE_HAS_GS)
 611                 return 0;
 612         pa = __pa(pcpu->lowcore->mcesad & MCESA_ORIGIN_MASK);
 613         if (MACHINE_HAS_GS)
 614                 pa |= pcpu->lowcore->mcesad & MCESA_LC_MASK;
 615         if (__pcpu_sigp_relax(pcpu->address, SIGP_STORE_ADDITIONAL_STATUS,
 616                               pa) != SIGP_CC_ORDER_CODE_ACCEPTED)
 617                 return -EIO;
 618         return 0;
 619 }
 620
 621 /*
 622  * Collect CPU state of the previous, crashed system.
 623  * There are four cases:
 624  * 1) standard zfcp/nvme dump
 625  *    condition: OLDMEM_BASE == NULL && is_ipl_type_dump() == true
 626  *    The state for all CPUs except the boot CPU needs to be collected
 627  *    with sigp stop-and-store-status. The boot CPU state is located in
 628  *    the absolute lowcore of the memory stored in the HSA. The zcore code
 629  *    will copy the boot CPU state from the HSA.
 630  * 2) stand-alone kdump for SCSI/NVMe (zfcp/nvme dump with swapped memory)
 631  *    condition: OLDMEM_BASE != NULL && is_ipl_type_dump() == true
 632  *    The state for all CPUs except the boot CPU needs to be collected
 633  *    with sigp stop-and-store-status. The firmware or the boot-loader
 634  *    stored the registers of the boot CPU in the absolute lowcore in the
 635  *    memory of the old system.
 636  * 3) kdump and the old kernel did not store the CPU state,
 637  *    or stand-alone kdump for DASD
 638  *    condition: OLDMEM_BASE != NULL && !is_kdump_kernel()
 639  *    The state for all CPUs except the boot CPU needs to be collected
 640  *    with sigp stop-and-store-status. The kexec code or the boot-loader
 641  *    stored the registers of the boot CPU in the memory of the old system.
 642  * 4) kdump and the old kernel stored the CPU state
 643  *    condition: OLDMEM_BASE != NULL && is_kdump_kernel()
 644  *    This case does not exist for s390 anymore, setup_arch explicitly
 645  *    deactivates the elfcorehdr= kernel parameter
 646  */
 647 static __init void smp_save_cpu_vxrs(struct save_area *sa, u16 addr,
 648                                      bool is_boot_cpu, unsigned long page)
 649 {
 650         __vector128 *vxrs = (__vector128 *) page;
 651
 652         if (is_boot_cpu)
 653                 vxrs = boot_cpu_vector_save_area;
 654         else
 655                 __pcpu_sigp_relax(addr, SIGP_STORE_ADDITIONAL_STATUS, page);
 656         save_area_add_vxrs(sa, vxrs);
 657 }
 658
 659 static __init void smp_save_cpu_regs(struct save_area *sa, u16 addr,
 660                                      bool is_boot_cpu, unsigned long page)
 661 {
 662         void *regs = (void *) page;
 663
 664         if (is_boot_cpu)
 665                 copy_oldmem_kernel(regs, (void *) __LC_FPREGS_SAVE_AREA, 512);
 666         else
 667                 __pcpu_sigp_relax(addr, SIGP_STORE_STATUS_AT_ADDRESS, page);
 668         save_area_add_regs(sa, regs);
 669 }
 670
 671 void __init smp_save_dump_cpus(void)
 672 {
 673         int addr, boot_cpu_addr, max_cpu_addr;
 674         struct save_area *sa;
 675         unsigned long page;
 676         bool is_boot_cpu;
 677
 678         if (!(OLDMEM_BASE || is_ipl_type_dump()))
 679                 /* No previous system present, normal boot. */
 680                 return;
 681         /* Allocate a page as dumping area for the store status sigps */
 682         page = memblock_phys_alloc_range(PAGE_SIZE, PAGE_SIZE, 0, 1UL << 31);
 683         if (!page)
 684                 panic("ERROR: Failed to allocate %lx bytes below %lx\n",
 685                       PAGE_SIZE, 1UL << 31);
 686
 687         /* Set multi-threading state to the previous system. */
 688         pcpu_set_smt(sclp.mtid_prev);
 689         boot_cpu_addr = stap();
 690         max_cpu_addr = SCLP_MAX_CORES << sclp.mtid_prev;
 691         for (addr = 0; addr <= max_cpu_addr; addr++) {
 692                 if (__pcpu_sigp_relax(addr, SIGP_SENSE, 0) ==
 693                     SIGP_CC_NOT_OPERATIONAL)
 694                         continue;
 695                 is_boot_cpu = (addr == boot_cpu_addr);
 696                 /* Allocate save area */
 697                 sa = save_area_alloc(is_boot_cpu);
 698                 if (!sa)
 699                         panic("could not allocate memory for save area\n");
 700                 if (MACHINE_HAS_VX)
 701                         /* Get the vector registers */
 702                         smp_save_cpu_vxrs(sa, addr, is_boot_cpu, page);
 703                 /*
 704                  * For a zfcp/nvme dump OLDMEM_BASE == NULL and the registers
 705                  * of the boot CPU are stored in the HSA. To retrieve
 706                  * these registers an SCLP request is required which is
 707                  * done by drivers/s390/char/zcore.c:init_cpu_info()
 708                  */
 709                 if (!is_boot_cpu || OLDMEM_BASE)
 710                         /* Get the CPU registers */
 711                         smp_save_cpu_regs(sa, addr, is_boot_cpu, page);
 712         }
 713         memblock_free(page, PAGE_SIZE);
 714         diag_dma_ops.diag308_reset();
 715         pcpu_set_smt(0);
 716 }
 717 #endif /* CONFIG_CRASH_DUMP */
 718
 719 void smp_cpu_set_polarization(int cpu, int val)
 720 {
 721         pcpu_devices[cpu].polarization = val;
 722 }
 723
 724 int smp_cpu_get_polarization(int cpu)
 725 {
 726         return pcpu_devices[cpu].polarization;
 727 }
 728
 729 int smp_cpu_get_cpu_address(int cpu)
 730 {
 731         return pcpu_devices[cpu].address;
 732 }
 733
 734 static void __ref smp_get_core_info(struct sclp_core_info *info, int early)
 735 {
 736         static int use_sigp_detection;
 737         int address;
 738
 739         if (use_sigp_detection || sclp_get_core_info(info, early)) {
 740                 use_sigp_detection = 1;
 741                 for (address = 0;
 742                      address < (SCLP_MAX_CORES << smp_cpu_mt_shift);
 743                      address += (1U << smp_cpu_mt_shift)) {
 744                         if (__pcpu_sigp_relax(address, SIGP_SENSE, 0) ==
 745                             SIGP_CC_NOT_OPERATIONAL)
 746                                 continue;
 747                         info->core[info->configured].core_id =
 748                                 address >> smp_cpu_mt_shift;
 749                         info->configured++;
 750                 }
 751                 info->combined = info->configured;
 752         }
 753 }
 754
 755 static int smp_add_present_cpu(int cpu);
 756
 757 static int smp_add_core(struct sclp_core_entry *core, cpumask_t *avail,
 758                         bool configured, bool early)
 759 {
 760         struct pcpu *pcpu;
 761         int cpu, nr, i;
 762         u16 address;
 763
 764         nr = 0;
 765         if (sclp.has_core_type && core->type != boot_core_type)
 766                 return nr;
 767         cpu = cpumask_first(avail);
 768         address = core->core_id << smp_cpu_mt_shift;
 769         for (i = 0; (i <= smp_cpu_mtid) && (cpu < nr_cpu_ids); i++) {
 770                 if (pcpu_find_address(cpu_present_mask, address + i))
 771                         continue;
 772                 pcpu = pcpu_devices + cpu;
 773                 pcpu->address = address + i;
 774                 if (configured)
 775                         pcpu->state = CPU_STATE_CONFIGURED;
 776                 else
 777                         pcpu->state = CPU_STATE_STANDBY;
 778                 smp_cpu_set_polarization(cpu, POLARIZATION_UNKNOWN);
 779                 set_cpu_present(cpu, true);
 780                 if (!early && smp_add_present_cpu(cpu) != 0)
 781                         set_cpu_present(cpu, false);
 782                 else
 783                         nr++;
 784                 cpumask_clear_cpu(cpu, avail);
 785                 cpu = cpumask_next(cpu, avail);
 786         }
 787         return nr;
 788 }
 789
 790 static int __smp_rescan_cpus(struct sclp_core_info *info, bool early)
 791 {
 792         struct sclp_core_entry *core;
 793         static cpumask_t avail;
 794         bool configured;
 795         u16 core_id;
 796         int nr, i;
 797
 798         get_online_cpus();
 799         mutex_lock(&smp_cpu_state_mutex);
 800         nr = 0;
 801         cpumask_xor(&avail, cpu_possible_mask, cpu_present_mask);
 802         /*
 803          * Add IPL core first (which got logical CPU number 0) to make sure
 804          * that all SMT threads get subsequent logical CPU numbers.
 805          */
 806         if (early) {
 807                 core_id = pcpu_devices[0].address >> smp_cpu_mt_shift;
 808                 for (i = 0; i < info->configured; i++) {
 809                         core = &info->core[i];
 810                         if (core->core_id == core_id) {
 811                                 nr += smp_add_core(core, &avail, true, early);
 812                                 break;
 813                         }
 814                 }
 815         }
 816         for (i = 0; i < info->combined; i++) {
 817                 configured = i < info->configured;
 818                 nr += smp_add_core(&info->core[i], &avail, configured, early);
 819         }
 820         mutex_unlock(&smp_cpu_state_mutex);
 821         put_online_cpus();
 822         return nr;
 823 }
 824
 825 void __init smp_detect_cpus(void)
 826 {
 827         unsigned int cpu, mtid, c_cpus, s_cpus;
 828         struct sclp_core_info *info;
 829         u16 address;
 830
 831         /* Get CPU information */
 832         info = memblock_alloc(sizeof(*info), 8);
 833         if (!info)
 834                 panic("%s: Failed to allocate %zu bytes align=0x%x\n",
 835                       __func__, sizeof(*info), 8);
 836         smp_get_core_info(info, 1);
 837         /* Find boot CPU type */
 838         if (sclp.has_core_type) {
 839                 address = stap();
 840                 for (cpu = 0; cpu < info->combined; cpu++)
 841                         if (info->core[cpu].core_id == address) {
 842                                 /* The boot cpu dictates the cpu type. */
 843                                 boot_core_type = info->core[cpu].type;
 844                                 break;
 845                         }
 846                 if (cpu >= info->combined)
 847                         panic("Could not find boot CPU type");
 848         }
 849
 850         /* Set multi-threading state for the current system */
 851         mtid = boot_core_type ? sclp.mtid : sclp.mtid_cp;
 852         mtid = (mtid < smp_max_threads) ? mtid : smp_max_threads - 1;
 853         pcpu_set_smt(mtid);
 854
 855         /* Print number of CPUs */
 856         c_cpus = s_cpus = 0;
 857         for (cpu = 0; cpu < info->combined; cpu++) {
 858                 if (sclp.has_core_type &&
 859                     info->core[cpu].type != boot_core_type)
 860                         continue;
 861                 if (cpu < info->configured)
 862                         c_cpus += smp_cpu_mtid + 1;
 863                 else
 864                         s_cpus += smp_cpu_mtid + 1;
 865         }
 866         pr_info("%d configured CPUs, %d standby CPUs\n", c_cpus, s_cpus);
 867
 868         /* Add CPUs present at boot */
 869         __smp_rescan_cpus(info, true);
 870         memblock_free_early((unsigned long)info, sizeof(*info));
 871 }
 872
 873 static void smp_init_secondary(void)
 874 {
 875         int cpu = raw_smp_processor_id();
 876
 877         S390_lowcore.last_update_clock = get_tod_clock();
 878         restore_access_regs(S390_lowcore.access_regs_save_area);
 879         cpu_init();
 880         rcu_cpu_starting(cpu);
 881         preempt_disable();
 882         init_cpu_timer();
 883         vtime_init();
 884         vdso_getcpu_init();
 885         pfault_init();
 886         notify_cpu_starting(cpu);
 887         if (topology_cpu_dedicated(cpu))
 888                 set_cpu_flag(CIF_DEDICATED_CPU);
 889         else
 890                 clear_cpu_flag(CIF_DEDICATED_CPU);
 891         set_cpu_online(cpu, true);
 892         update_cpu_masks();
 893         inc_irq_stat(CPU_RST);
 894         local_irq_enable();
 895         cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
 896 }
 897
 898 /*
 899  *      Activate a secondary processor.
 900  */
 901 static void __no_sanitize_address smp_start_secondary(void *cpuvoid)
 902 {
 903         S390_lowcore.restart_stack = (unsigned long) restart_stack;
 904         S390_lowcore.restart_fn = (unsigned long) do_restart;
 905         S390_lowcore.restart_data = 0;
 906         S390_lowcore.restart_source = -1UL;
 907         __ctl_load(S390_lowcore.cregs_save_area, 0, 15);
 908         __load_psw_mask(PSW_KERNEL_BITS | PSW_MASK_DAT);
 909         CALL_ON_STACK_NORETURN(smp_init_secondary, S390_lowcore.kernel_stack);
 910 }
 911
 912 /* Upping and downing of CPUs */
 913 int __cpu_up(unsigned int cpu, struct task_struct *tidle)
 914 {
 915         struct pcpu *pcpu = pcpu_devices + cpu;
 916         int rc;
 917
 918         if (pcpu->state != CPU_STATE_CONFIGURED)
 919                 return -EIO;
 920         if (pcpu_sigp_retry(pcpu, SIGP_INITIAL_CPU_RESET, 0) !=
 921             SIGP_CC_ORDER_CODE_ACCEPTED)
 922                 return -EIO;
 923
 924         rc = pcpu_alloc_lowcore(pcpu, cpu);
 925         if (rc)
 926                 return rc;
 927         pcpu_prepare_secondary(pcpu, cpu);
 928         pcpu_attach_task(pcpu, tidle);
 929         pcpu_start_fn(pcpu, smp_start_secondary, NULL);
 930         /* Wait until cpu puts itself in the online & active maps */
 931         while (!cpu_online(cpu))
 932                 cpu_relax();
 933         return 0;
 934 }
 935
 936 static unsigned int setup_possible_cpus __initdata;
 937
 938 static int __init _setup_possible_cpus(char *s)
 939 {
 940         get_option(&s, &setup_possible_cpus);
 941         return 0;
 942 }
 943 early_param("possible_cpus", _setup_possible_cpus);
 944
 945 int __cpu_disable(void)
 946 {
 947         unsigned long cregs[16];
 948
 949         /* Handle possible pending IPIs */
 950         smp_handle_ext_call();
 951         set_cpu_online(smp_processor_id(), false);
 952         update_cpu_masks();
 953         /* Disable pseudo page faults on this cpu. */
 954         pfault_fini();
 955         /* Disable interrupt sources via control register. */
 956         __ctl_store(cregs, 0, 15);
 957         cregs[0]  &= ~0x0000ee70UL;     /* disable all external interrupts */
 958         cregs[6]  &= ~0xff000000UL;     /* disable all I/O interrupts */
 959         cregs[14] &= ~0x1f000000UL;     /* disable most machine checks */
 960         __ctl_load(cregs, 0, 15);
 961         clear_cpu_flag(CIF_NOHZ_DELAY);
 962         return 0;
 963 }
 964
 965 void __cpu_die(unsigned int cpu)
 966 {
 967         struct pcpu *pcpu;
 968
 969         /* Wait until target cpu is down */
 970         pcpu = pcpu_devices + cpu;
 971         while (!pcpu_stopped(pcpu))
 972                 cpu_relax();
 973         pcpu_free_lowcore(pcpu);
 974         cpumask_clear_cpu(cpu, mm_cpumask(&init_mm));
 975         cpumask_clear_cpu(cpu, &init_mm.context.cpu_attach_mask);
 976 }
 977
 978 void __noreturn cpu_die(void)
 979 {
 980         idle_task_exit();
 981         __bpon();
 982         pcpu_sigp_retry(pcpu_devices + smp_processor_id(), SIGP_STOP, 0);
 983         for (;;) ;
 984 }
 985
 986 void __init smp_fill_possible_mask(void)
 987 {
 988         unsigned int possible, sclp_max, cpu;
 989
 990         sclp_max = max(sclp.mtid, sclp.mtid_cp) + 1;
 991         sclp_max = min(smp_max_threads, sclp_max);
 992         sclp_max = (sclp.max_cores * sclp_max) ?: nr_cpu_ids;
 993         possible = setup_possible_cpus ?: nr_cpu_ids;
 994         possible = min(possible, sclp_max);
 995         for (cpu = 0; cpu < possible && cpu < nr_cpu_ids; cpu++)
 996                 set_cpu_possible(cpu, true);
 997 }
 998
 999 void __init smp_prepare_cpus(unsigned int max_cpus)
1000 {
1001         /* request the 0x1201 emergency signal external interrupt */
1002         if (register_external_irq(EXT_IRQ_EMERGENCY_SIG, do_ext_call_interrupt))
1003                 panic("Couldn't request external interrupt 0x1201");
1004         /* request the 0x1202 external call external interrupt */
1005         if (register_external_irq(EXT_IRQ_EXTERNAL_CALL, do_ext_call_interrupt))
1006                 panic("Couldn't request external interrupt 0x1202");
1007 }
1008
1009 void __init smp_prepare_boot_cpu(void)
1010 {
1011         struct pcpu *pcpu = pcpu_devices;
1012
1013         WARN_ON(!cpu_present(0) || !cpu_online(0));
1014         pcpu->state = CPU_STATE_CONFIGURED;
1015         pcpu->lowcore = (struct lowcore *)(unsigned long) store_prefix();
1016         S390_lowcore.percpu_offset = __per_cpu_offset[0];
1017         smp_cpu_set_polarization(0, POLARIZATION_UNKNOWN);
1018 }
1019
1020 void __init smp_setup_processor_id(void)
1021 {
1022         pcpu_devices[0].address = stap();
1023         S390_lowcore.cpu_nr = 0;
1024         S390_lowcore.spinlock_lockval = arch_spin_lockval(0);
1025         S390_lowcore.spinlock_index = 0;
1026 }
1027
1028 /*
1029  * the frequency of the profiling timer can be changed
1030  * by writing a multiplier value into /proc/profile.
1031  *
1032  * usually you want to run this on all CPUs ;)
1033  */
1034 int setup_profiling_timer(unsigned int multiplier)
1035 {
1036         return 0;
1037 }
1038
1039 static ssize_t cpu_configure_show(struct device *dev,
1040                                   struct device_attribute *attr, char *buf)
1041 {
1042         ssize_t count;
1043
1044         mutex_lock(&smp_cpu_state_mutex);
1045         count = sprintf(buf, "%d\n", pcpu_devices[dev->id].state);
1046         mutex_unlock(&smp_cpu_state_mutex);
1047         return count;
1048 }
1049
1050 static ssize_t cpu_configure_store(struct device *dev,
1051                                    struct device_attribute *attr,
1052                                    const char *buf, size_t count)
1053 {
1054         struct pcpu *pcpu;
1055         int cpu, val, rc, i;
1056         char delim;
1057
1058         if (sscanf(buf, "%d %c", &val, &delim) != 1)
1059                 return -EINVAL;
1060         if (val != 0 && val != 1)
1061                 return -EINVAL;
1062         get_online_cpus();
1063         mutex_lock(&smp_cpu_state_mutex);
1064         rc = -EBUSY;
1065         /* disallow configuration changes of online cpus and cpu 0 */
1066         cpu = dev->id;
1067         cpu = smp_get_base_cpu(cpu);
1068         if (cpu == 0)
1069                 goto out;
1070         for (i = 0; i <= smp_cpu_mtid; i++)
1071                 if (cpu_online(cpu + i))
1072                         goto out;
1073         pcpu = pcpu_devices + cpu;
1074         rc = 0;
1075         switch (val) {
1076         case 0:
1077                 if (pcpu->state != CPU_STATE_CONFIGURED)
1078                         break;
1079                 rc = sclp_core_deconfigure(pcpu->address >> smp_cpu_mt_shift);
1080                 if (rc)
1081                         break;
1082                 for (i = 0; i <= smp_cpu_mtid; i++) {
1083                         if (cpu + i >= nr_cpu_ids || !cpu_present(cpu + i))
1084                                 continue;
1085                         pcpu[i].state = CPU_STATE_STANDBY;
1086                         smp_cpu_set_polarization(cpu + i,
1087                                                  POLARIZATION_UNKNOWN);
1088                 }
1089                 topology_expect_change();
1090                 break;
1091         case 1:
1092                 if (pcpu->state != CPU_STATE_STANDBY)
1093                         break;
1094                 rc = sclp_core_configure(pcpu->address >> smp_cpu_mt_shift);
1095                 if (rc)
1096                         break;
1097                 for (i = 0; i <= smp_cpu_mtid; i++) {
1098                         if (cpu + i >= nr_cpu_ids || !cpu_present(cpu + i))
1099                                 continue;
1100                         pcpu[i].state = CPU_STATE_CONFIGURED;
1101                         smp_cpu_set_polarization(cpu + i,
1102                                                  POLARIZATION_UNKNOWN);
1103                 }
1104                 topology_expect_change();
1105                 break;
1106         default:
1107                 break;
1108         }
1109 out:
1110         mutex_unlock(&smp_cpu_state_mutex);
1111         put_online_cpus();
1112         return rc ? rc : count;
1113 }
1114 static DEVICE_ATTR(configure, 0644, cpu_configure_show, cpu_configure_store);
1115
1116 static ssize_t show_cpu_address(struct device *dev,
1117                                 struct device_attribute *attr, char *buf)
1118 {
1119         return sprintf(buf, "%d\n", pcpu_devices[dev->id].address);
1120 }
1121 static DEVICE_ATTR(address, 0444, show_cpu_address, NULL);
1122
1123 static struct attribute *cpu_common_attrs[] = {
1124         &dev_attr_configure.attr,
1125         &dev_attr_address.attr,
1126         NULL,
1127 };
1128
1129 static struct attribute_group cpu_common_attr_group = {
1130         .attrs = cpu_common_attrs,
1131 };
1132
1133 static struct attribute *cpu_online_attrs[] = {
1134         &dev_attr_idle_count.attr,
1135         &dev_attr_idle_time_us.attr,
1136         NULL,
1137 };
1138
1139 static struct attribute_group cpu_online_attr_group = {
1140         .attrs = cpu_online_attrs,
1141 };
1142
1143 static int smp_cpu_online(unsigned int cpu)
1144 {
1145         struct device *s = &per_cpu(cpu_device, cpu)->dev;
1146
1147         return sysfs_create_group(&s->kobj, &cpu_online_attr_group);
1148 }
1149
1150 static int smp_cpu_pre_down(unsigned int cpu)
1151 {
1152         struct device *s = &per_cpu(cpu_device, cpu)->dev;
1153
1154         sysfs_remove_group(&s->kobj, &cpu_online_attr_group);
1155         return 0;
1156 }
1157
1158 static int smp_add_present_cpu(int cpu)
1159 {
1160         struct device *s;
1161         struct cpu *c;
1162         int rc;
1163
1164         c = kzalloc(sizeof(*c), GFP_KERNEL);
1165         if (!c)
1166                 return -ENOMEM;
1167         per_cpu(cpu_device, cpu) = c;
1168         s = &c->dev;
1169         c->hotpluggable = 1;
1170         rc = register_cpu(c, cpu);
1171         if (rc)
1172                 goto out;
1173         rc = sysfs_create_group(&s->kobj, &cpu_common_attr_group);
1174         if (rc)
1175                 goto out_cpu;
1176         rc = topology_cpu_init(c);
1177         if (rc)
1178                 goto out_topology;
1179         return 0;
1180
1181 out_topology:
1182         sysfs_remove_group(&s->kobj, &cpu_common_attr_group);
1183 out_cpu:
1184         unregister_cpu(c);
1185 out:
1186         return rc;
1187 }
1188
1189 int __ref smp_rescan_cpus(void)
1190 {
1191         struct sclp_core_info *info;
1192         int nr;
1193
1194         info = kzalloc(sizeof(*info), GFP_KERNEL);
1195         if (!info)
1196                 return -ENOMEM;
1197         smp_get_core_info(info, 0);
1198         nr = __smp_rescan_cpus(info, false);
1199         kfree(info);
1200         if (nr)
1201                 topology_schedule_update();
1202         return 0;
1203 }
1204
1205 static ssize_t __ref rescan_store(struct device *dev,
1206                                   struct device_attribute *attr,
1207                                   const char *buf,
1208                                   size_t count)
1209 {
1210         int rc;
1211
1212         rc = lock_device_hotplug_sysfs();
1213         if (rc)
1214                 return rc;
1215         rc = smp_rescan_cpus();
1216         unlock_device_hotplug();
1217         return rc ? rc : count;
1218 }
1219 static DEVICE_ATTR_WO(rescan);
1220
1221 static int __init s390_smp_init(void)
1222 {
1223         int cpu, rc = 0;
1224
1225         rc = device_create_file(cpu_subsys.dev_root, &dev_attr_rescan);
1226         if (rc)
1227                 return rc;
1228         for_each_present_cpu(cpu) {
1229                 rc = smp_add_present_cpu(cpu);
1230                 if (rc)
1231                         goto out;
1232         }
1233
1234         rc = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "s390/smp:online",
1235                                smp_cpu_online, smp_cpu_pre_down);
1236         rc = rc <= 0 ? rc : 0;
1237 out:
1238         return rc;
1239 }
1240 subsys_initcall(s390_smp_init);