text: // SPDX-License-Identifier: GPL-2.0
  /*
   *  SMP related functions
   *
   *    Copyright IBM Corp. 1999, 2012
   *    Author(s): Denis Joseph Barrow,
   *		 Martin Schwidefsky <schwidefsky@de.ibm.com>,
   *		 Heiko Carstens <heiko.carstens@de.ibm.com>,
   *
   *  based on other smp stuff by
   *    (c) 1995 Alan Cox, CymruNET Ltd  <alan@cymru.net>
   *    (c) 1998 Ingo Molnar
   *
   * The code outside of smp.c uses logical cpu numbers, only smp.c does
   * the translation of logical to physical cpu ids. All new code that
   * operates on physical cpu numbers needs to go into smp.c.
   */
  
  #define KMSG_COMPONENT "cpu"
  #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
  
  #include <linux/workqueue.h>
  #include <linux/memblock.h>
  #include <linux/export.h>
  #include <linux/init.h>
  #include <linux/mm.h>
  #include <linux/err.h>
  #include <linux/spinlock.h>
  #include <linux/kernel_stat.h>
  #include <linux/delay.h>
  #include <linux/interrupt.h>
  #include <linux/irqflags.h>
  #include <linux/cpu.h>
  #include <linux/slab.h>
  #include <linux/sched/hotplug.h>
  #include <linux/sched/task_stack.h>
  #include <linux/crash_dump.h>
  #include <linux/kprobes.h>
  #include <asm/asm-offsets.h>
  #include <asm/diag.h>
  #include <asm/switch_to.h>
  #include <asm/facility.h>
  #include <asm/ipl.h>
  #include <asm/setup.h>
  #include <asm/irq.h>
  #include <asm/tlbflush.h>
  #include <asm/vtimer.h>
  #include <asm/lowcore.h>
  #include <asm/sclp.h>
  #include <asm/vdso.h>
  #include <asm/debug.h>
  #include <asm/os_info.h>
  #include <asm/sigp.h>
  #include <asm/idle.h>
  #include <asm/nmi.h>
  #include <asm/stacktrace.h>
  #include <asm/topology.h>
  #include "entry.h"
  
  enum {
  	ec_schedule = 0,
  	ec_call_function_single,
  	ec_stop_cpu,
  };
  
  enum {
  	CPU_STATE_STANDBY,
  	CPU_STATE_CONFIGURED,
  };
  
  static DEFINE_PER_CPU(struct cpu *, cpu_device);
  
  struct pcpu {
  	struct lowcore *lowcore;	/* lowcore page(s) for the cpu */
  	unsigned long ec_mask;		/* bit mask for ec_xxx functions */
  	unsigned long ec_clk;		/* sigp timestamp for ec_xxx */
  	signed char state;		/* physical cpu state */
  	signed char polarization;	/* physical polarization */
  	u16 address;			/* physical cpu address */
  };
  
  static u8 boot_core_type;
  static struct pcpu pcpu_devices[NR_CPUS];
  
  unsigned int smp_cpu_mt_shift;
  EXPORT_SYMBOL(smp_cpu_mt_shift);
  
  unsigned int smp_cpu_mtid;
  EXPORT_SYMBOL(smp_cpu_mtid);
  
  #ifdef CONFIG_CRASH_DUMP
  __vector128 __initdata boot_cpu_vector_save_area[__NUM_VXRS];
  #endif
  
  static unsigned int smp_max_threads __initdata = -1U;
  
  static int __init early_nosmt(char *s)
  {
  	smp_max_threads = 1;
  	return 0;
  }
  early_param("nosmt", early_nosmt);
  
  static int __init early_smt(char *s)
  {
  	get_option(&s, &smp_max_threads);
  	return 0;
  }
  early_param("smt", early_smt);
  
  /*
   * The smp_cpu_state_mutex must be held when changing the state or polarization
   * member of a pcpu data structure within the pcpu_devices arreay.
   */
  DEFINE_MUTEX(smp_cpu_state_mutex);
  
  /*
   * Signal processor helper functions.
   */
  static inline int __pcpu_sigp_relax(u16 addr, u8 order, unsigned long parm)
  {
  	int cc;
  
  	while (1) {
  		cc = __pcpu_sigp(addr, order, parm, NULL);
  		if (cc != SIGP_CC_BUSY)
  			return cc;
  		cpu_relax();
  	}
  }
  
  static int pcpu_sigp_retry(struct pcpu *pcpu, u8 order, u32 parm)
  {
  	int cc, retry;
  
  	for (retry = 0; ; retry++) {
  		cc = __pcpu_sigp(pcpu->address, order, parm, NULL);
  		if (cc != SIGP_CC_BUSY)
  			break;
  		if (retry >= 3)
  			udelay(10);
  	}
  	return cc;
  }
  
  static inline int pcpu_stopped(struct pcpu *pcpu)
  {
  	u32 uninitialized_var(status);
  
  	if (__pcpu_sigp(pcpu->address, SIGP_SENSE,
  			0, &status) != SIGP_CC_STATUS_STORED)
  		return 0;
  	return !!(status & (SIGP_STATUS_CHECK_STOP|SIGP_STATUS_STOPPED));
  }
  
  static inline int pcpu_running(struct pcpu *pcpu)
  {
  	if (__pcpu_sigp(pcpu->address, SIGP_SENSE_RUNNING,
  			0, NULL) != SIGP_CC_STATUS_STORED)
  		return 1;
  	/* Status stored condition code is equivalent to cpu not running. */
  	return 0;
  }
  
  /*
   * Find struct pcpu by cpu address.
   */
  static struct pcpu *pcpu_find_address(const struct cpumask *mask, u16 address)
  {
  	int cpu;
  
  	for_each_cpu(cpu, mask)
  		if (pcpu_devices[cpu].address == address)
  			return pcpu_devices + cpu;
  	return NULL;
  }
  
  static void pcpu_ec_call(struct pcpu *pcpu, int ec_bit)
  {
  	int order;
  
  	if (test_and_set_bit(ec_bit, &pcpu->ec_mask))
  		return;
  	order = pcpu_running(pcpu) ? SIGP_EXTERNAL_CALL : SIGP_EMERGENCY_SIGNAL;
  	pcpu->ec_clk = get_tod_clock_fast();
  	pcpu_sigp_retry(pcpu, order, 0);
  }
  
  static int pcpu_alloc_lowcore(struct pcpu *pcpu, int cpu)
  {
  	unsigned long async_stack, nodat_stack;
  	struct lowcore *lc;
  
  	if (pcpu != &pcpu_devices[0]) {
  		pcpu->lowcore =	(struct lowcore *)
  			__get_free_pages(GFP_KERNEL | GFP_DMA, LC_ORDER);
  		nodat_stack = __get_free_pages(GFP_KERNEL, THREAD_SIZE_ORDER);
  		if (!pcpu->lowcore || !nodat_stack)
  			goto out;
  	} else {
  		nodat_stack = pcpu->lowcore->nodat_stack - STACK_INIT_OFFSET;
  	}
  	async_stack = stack_alloc();
  	if (!async_stack)
  		goto out;
  	lc = pcpu->lowcore;
  	memcpy(lc, &S390_lowcore, 512);
  	memset((char *) lc + 512, 0, sizeof(*lc) - 512);
  	lc->async_stack = async_stack + STACK_INIT_OFFSET;
  	lc->nodat_stack = nodat_stack + STACK_INIT_OFFSET;
  	lc->cpu_nr = cpu;
  	lc->spinlock_lockval = arch_spin_lockval(cpu);
  	lc->spinlock_index = 0;
  	lc->br_r1_trampoline = 0x07f1;	/* br %r1 */
  	if (nmi_alloc_per_cpu(lc))
  		goto out_async;
  	if (vdso_alloc_per_cpu(lc))
  		goto out_mcesa;
  	lowcore_ptr[cpu] = lc;
  	pcpu_sigp_retry(pcpu, SIGP_SET_PREFIX, (u32)(unsigned long) lc);
  	return 0;
  
  out_mcesa:
  	nmi_free_per_cpu(lc);
  out_async:
  	stack_free(async_stack);
  out:
  	if (pcpu != &pcpu_devices[0]) {
  		free_pages(nodat_stack, THREAD_SIZE_ORDER);
  		free_pages((unsigned long) pcpu->lowcore, LC_ORDER);
  	}
  	return -ENOMEM;
  }
  
  static void pcpu_free_lowcore(struct pcpu *pcpu)
  {
  	unsigned long async_stack, nodat_stack, lowcore;
  
  	nodat_stack = pcpu->lowcore->nodat_stack - STACK_INIT_OFFSET;
  	async_stack = pcpu->lowcore->async_stack - STACK_INIT_OFFSET;
  	lowcore = (unsigned long) pcpu->lowcore;
  
  	pcpu_sigp_retry(pcpu, SIGP_SET_PREFIX, 0);
  	lowcore_ptr[pcpu - pcpu_devices] = NULL;
  	vdso_free_per_cpu(pcpu->lowcore);
  	nmi_free_per_cpu(pcpu->lowcore);
  	stack_free(async_stack);
  	if (pcpu == &pcpu_devices[0])
  		return;
  	free_pages(nodat_stack, THREAD_SIZE_ORDER);
  	free_pages(lowcore, LC_ORDER);
  }
  
  static void pcpu_prepare_secondary(struct pcpu *pcpu, int cpu)
  {
  	struct lowcore *lc = pcpu->lowcore;
  
  	cpumask_set_cpu(cpu, &init_mm.context.cpu_attach_mask);
  	cpumask_set_cpu(cpu, mm_cpumask(&init_mm));
  	lc->cpu_nr = cpu;
  	lc->spinlock_lockval = arch_spin_lockval(cpu);
  	lc->spinlock_index = 0;
  	lc->percpu_offset = __per_cpu_offset[cpu];
  	lc->kernel_asce = S390_lowcore.kernel_asce;
  	lc->machine_flags = S390_lowcore.machine_flags;
  	lc->user_timer = lc->system_timer =
  		lc->steal_timer = lc->avg_steal_timer = 0;
  	__ctl_store(lc->cregs_save_area, 0, 15);
  	save_access_regs((unsigned int *) lc->access_regs_save_area);
  	memcpy(lc->stfle_fac_list, S390_lowcore.stfle_fac_list,
  	       sizeof(lc->stfle_fac_list));
  	memcpy(lc->alt_stfle_fac_list, S390_lowcore.alt_stfle_fac_list,
  	       sizeof(lc->alt_stfle_fac_list));
  	arch_spin_lock_setup(cpu);
  }
  
  static void pcpu_attach_task(struct pcpu *pcpu, struct task_struct *tsk)
  {
  	struct lowcore *lc = pcpu->lowcore;
  
  	lc->kernel_stack = (unsigned long) task_stack_page(tsk)
  		+ THREAD_SIZE - STACK_FRAME_OVERHEAD - sizeof(struct pt_regs);
  	lc->current_task = (unsigned long) tsk;
  	lc->lpp = LPP_MAGIC;
  	lc->current_pid = tsk->pid;
  	lc->user_timer = tsk->thread.user_timer;
  	lc->guest_timer = tsk->thread.guest_timer;
  	lc->system_timer = tsk->thread.system_timer;
  	lc->hardirq_timer = tsk->thread.hardirq_timer;
  	lc->softirq_timer = tsk->thread.softirq_timer;
  	lc->steal_timer = 0;
  }
  
  static void pcpu_start_fn(struct pcpu *pcpu, void (*func)(void *), void *data)
  {
  	struct lowcore *lc = pcpu->lowcore;
  
  	lc->restart_stack = lc->nodat_stack;
  	lc->restart_fn = (unsigned long) func;
  	lc->restart_data = (unsigned long) data;
  	lc->restart_source = -1UL;
  	pcpu_sigp_retry(pcpu, SIGP_RESTART, 0);
  }
  
  /*
   * Call function via PSW restart on pcpu and stop the current cpu.
   */
  static void __pcpu_delegate(void (*func)(void*), void *data)
  {
  	func(data);	/* should not return */
  }
  
  static void __no_sanitize_address pcpu_delegate(struct pcpu *pcpu,
  						void (*func)(void *),
  						void *data, unsigned long stack)
  {
  	struct lowcore *lc = lowcore_ptr[pcpu - pcpu_devices];
  	unsigned long source_cpu = stap();
  
  	__load_psw_mask(PSW_KERNEL_BITS | PSW_MASK_DAT);
  	if (pcpu->address == source_cpu)
  		CALL_ON_STACK(__pcpu_delegate, stack, 2, func, data);
  	/* Stop target cpu (if func returns this stops the current cpu). */
  	pcpu_sigp_retry(pcpu, SIGP_STOP, 0);
  	/* Restart func on the target cpu and stop the current cpu. */
  	mem_assign_absolute(lc->restart_stack, stack);
  	mem_assign_absolute(lc->restart_fn, (unsigned long) func);
  	mem_assign_absolute(lc->restart_data, (unsigned long) data);
  	mem_assign_absolute(lc->restart_source, source_cpu);
  	__bpon();
  	asm volatile(
  		"0:	sigp	0,%0,%2	# sigp restart to target cpu\n"
  		"	brc	2,0b	# busy, try again\n"
  		"1:	sigp	0,%1,%3	# sigp stop to current cpu\n"
  		"	brc	2,1b	# busy, try again\n"
  		: : "d" (pcpu->address), "d" (source_cpu),
  		    "K" (SIGP_RESTART), "K" (SIGP_STOP)
  		: "0", "1", "cc");
  	for (;;) ;
  }
  
  /*
   * Enable additional logical cpus for multi-threading.
   */
  static int pcpu_set_smt(unsigned int mtid)
  {
  	int cc;
  
  	if (smp_cpu_mtid == mtid)
  		return 0;
  	cc = __pcpu_sigp(0, SIGP_SET_MULTI_THREADING, mtid, NULL);
  	if (cc == 0) {
  		smp_cpu_mtid = mtid;
  		smp_cpu_mt_shift = 0;
  		while (smp_cpu_mtid >= (1U << smp_cpu_mt_shift))
  			smp_cpu_mt_shift++;
  		pcpu_devices[0].address = stap();
  	}
  	return cc;
  }
  
  /*
   * Call function on an online CPU.
   */
  void smp_call_online_cpu(void (*func)(void *), void *data)
  {
  	struct pcpu *pcpu;
  
  	/* Use the current cpu if it is online. */
  	pcpu = pcpu_find_address(cpu_online_mask, stap());
  	if (!pcpu)
  		/* Use the first online cpu. */
  		pcpu = pcpu_devices + cpumask_first(cpu_online_mask);
  	pcpu_delegate(pcpu, func, data, (unsigned long) restart_stack);
  }
  
  /*
   * Call function on the ipl CPU.
   */
  void smp_call_ipl_cpu(void (*func)(void *), void *data)
  {
  	struct lowcore *lc = pcpu_devices->lowcore;
  
  	if (pcpu_devices[0].address == stap())
  		lc = &S390_lowcore;
  
  	pcpu_delegate(&pcpu_devices[0], func, data,
  		      lc->nodat_stack);
  }
  
  int smp_find_processor_id(u16 address)
  {
  	int cpu;
  
  	for_each_present_cpu(cpu)
  		if (pcpu_devices[cpu].address == address)
  			return cpu;
  	return -1;
  }
  
  bool arch_vcpu_is_preempted(int cpu)
  {
  	if (test_cpu_flag_of(CIF_ENABLED_WAIT, cpu))
  		return false;
  	if (pcpu_running(pcpu_devices + cpu))
  		return false;
  	return true;
  }
  EXPORT_SYMBOL(arch_vcpu_is_preempted);
  
  void smp_yield_cpu(int cpu)
  {
  	if (MACHINE_HAS_DIAG9C) {
  		diag_stat_inc_norecursion(DIAG_STAT_X09C);
  		asm volatile("diag %0,0,0x9c"
  			     : : "d" (pcpu_devices[cpu].address));
  	} else if (MACHINE_HAS_DIAG44 && !smp_cpu_mtid) {
  		diag_stat_inc_norecursion(DIAG_STAT_X044);
  		asm volatile("diag 0,0,0x44");
  	}
  }
  
  /*
   * Send cpus emergency shutdown signal. This gives the cpus the
   * opportunity to complete outstanding interrupts.
   */
  void notrace smp_emergency_stop(void)
  {
  	cpumask_t cpumask;
  	u64 end;
  	int cpu;
  
  	cpumask_copy(&cpumask, cpu_online_mask);
  	cpumask_clear_cpu(smp_processor_id(), &cpumask);
  
  	end = get_tod_clock() + (1000000UL << 12);
  	for_each_cpu(cpu, &cpumask) {
  		struct pcpu *pcpu = pcpu_devices + cpu;
  		set_bit(ec_stop_cpu, &pcpu->ec_mask);
  		while (__pcpu_sigp(pcpu->address, SIGP_EMERGENCY_SIGNAL,
  				   0, NULL) == SIGP_CC_BUSY &&
  		       get_tod_clock() < end)
  			cpu_relax();
  	}
  	while (get_tod_clock() < end) {
  		for_each_cpu(cpu, &cpumask)
  			if (pcpu_stopped(pcpu_devices + cpu))
  				cpumask_clear_cpu(cpu, &cpumask);
  		if (cpumask_empty(&cpumask))
  			break;
  		cpu_relax();
  	}
  }
  NOKPROBE_SYMBOL(smp_emergency_stop);
  
  /*
   * Stop all cpus but the current one.
   */
  void smp_send_stop(void)
  {
  	int cpu;
  
  	/* Disable all interrupts/machine checks */
  	__load_psw_mask(PSW_KERNEL_BITS | PSW_MASK_DAT);
  	trace_hardirqs_off();
  
  	debug_set_critical();
  
  	if (oops_in_progress)
  		smp_emergency_stop();
  
  	/* stop all processors */
  	for_each_online_cpu(cpu) {
  		if (cpu == smp_processor_id())
  			continue;
  		pcpu_sigp_retry(pcpu_devices + cpu, SIGP_STOP, 0);
  		while (!pcpu_stopped(pcpu_devices + cpu))
  			cpu_relax();
  	}
  }
  
  /*
   * This is the main routine where commands issued by other
   * cpus are handled.
   */
  static void smp_handle_ext_call(void)
  {
  	unsigned long bits;
  
  	/* handle bit signal external calls */
  	bits = xchg(&pcpu_devices[smp_processor_id()].ec_mask, 0);
  	if (test_bit(ec_stop_cpu, &bits))
  		smp_stop_cpu();
  	if (test_bit(ec_schedule, &bits))
  		scheduler_ipi();
  	if (test_bit(ec_call_function_single, &bits))
  		generic_smp_call_function_single_interrupt();
  }
  
  static void do_ext_call_interrupt(struct ext_code ext_code,
  				  unsigned int param32, unsigned long param64)
  {
  	inc_irq_stat(ext_code.code == 0x1202 ? IRQEXT_EXC : IRQEXT_EMS);
  	smp_handle_ext_call();
  }
  
  void arch_send_call_function_ipi_mask(const struct cpumask *mask)
  {
  	int cpu;
  
  	for_each_cpu(cpu, mask)
  		pcpu_ec_call(pcpu_devices + cpu, ec_call_function_single);
  }
  
  void arch_send_call_function_single_ipi(int cpu)
  {
  	pcpu_ec_call(pcpu_devices + cpu, ec_call_function_single);
  }
  
  /*
   * this function sends a 'reschedule' IPI to another CPU.
   * it goes straight through and wastes no time serializing
   * anything. Worst case is that we lose a reschedule ...
   */
  void smp_send_reschedule(int cpu)
  {
  	pcpu_ec_call(pcpu_devices + cpu, ec_schedule);
  }
  
  /*
   * parameter area for the set/clear control bit callbacks
   */
  struct ec_creg_mask_parms {
  	unsigned long orval;
  	unsigned long andval;
  	int cr;
  };
  
  /*
   * callback for setting/clearing control bits
   */
  static void smp_ctl_bit_callback(void *info)
  {
  	struct ec_creg_mask_parms *pp = info;
  	unsigned long cregs[16];
  
  	__ctl_store(cregs, 0, 15);
  	cregs[pp->cr] = (cregs[pp->cr] & pp->andval) | pp->orval;
  	__ctl_load(cregs, 0, 15);
  }
  
  /*
   * Set a bit in a control register of all cpus
   */
  void smp_ctl_set_bit(int cr, int bit)
  {
  	struct ec_creg_mask_parms parms = { 1UL << bit, -1UL, cr };
  
  	on_each_cpu(smp_ctl_bit_callback, &parms, 1);
  }
  EXPORT_SYMBOL(smp_ctl_set_bit);
  
  /*
   * Clear a bit in a control register of all cpus
   */
  void smp_ctl_clear_bit(int cr, int bit)
  {
  	struct ec_creg_mask_parms parms = { 0, ~(1UL << bit), cr };
  
  	on_each_cpu(smp_ctl_bit_callback, &parms, 1);
  }
  EXPORT_SYMBOL(smp_ctl_clear_bit);
  
  #ifdef CONFIG_CRASH_DUMP
  
  int smp_store_status(int cpu)
  {
  	struct pcpu *pcpu = pcpu_devices + cpu;
  	unsigned long pa;
  
  	pa = __pa(&pcpu->lowcore->floating_pt_save_area);
  	if (__pcpu_sigp_relax(pcpu->address, SIGP_STORE_STATUS_AT_ADDRESS,
  			      pa) != SIGP_CC_ORDER_CODE_ACCEPTED)
  		return -EIO;
  	if (!MACHINE_HAS_VX && !MACHINE_HAS_GS)
  		return 0;
  	pa = __pa(pcpu->lowcore->mcesad & MCESA_ORIGIN_MASK);
  	if (MACHINE_HAS_GS)
  		pa |= pcpu->lowcore->mcesad & MCESA_LC_MASK;
  	if (__pcpu_sigp_relax(pcpu->address, SIGP_STORE_ADDITIONAL_STATUS,
  			      pa) != SIGP_CC_ORDER_CODE_ACCEPTED)
  		return -EIO;
  	return 0;
  }
  
  /*
   * Collect CPU state of the previous, crashed system.
   * There are four cases:
   * 1) standard zfcp dump
   *    condition: OLDMEM_BASE == NULL && ipl_info.type == IPL_TYPE_FCP_DUMP
   *    The state for all CPUs except the boot CPU needs to be collected
   *    with sigp stop-and-store-status. The boot CPU state is located in
   *    the absolute lowcore of the memory stored in the HSA. The zcore code
   *    will copy the boot CPU state from the HSA.
   * 2) stand-alone kdump for SCSI (zfcp dump with swapped memory)
   *    condition: OLDMEM_BASE != NULL && ipl_info.type == IPL_TYPE_FCP_DUMP
   *    The state for all CPUs except the boot CPU needs to be collected
   *    with sigp stop-and-store-status. The firmware or the boot-loader
   *    stored the registers of the boot CPU in the absolute lowcore in the
   *    memory of the old system.
   * 3) kdump and the old kernel did not store the CPU state,
   *    or stand-alone kdump for DASD
   *    condition: OLDMEM_BASE != NULL && !is_kdump_kernel()
   *    The state for all CPUs except the boot CPU needs to be collected
   *    with sigp stop-and-store-status. The kexec code or the boot-loader
   *    stored the registers of the boot CPU in the memory of the old system.
   * 4) kdump and the old kernel stored the CPU state
   *    condition: OLDMEM_BASE != NULL && is_kdump_kernel()
   *    This case does not exist for s390 anymore, setup_arch explicitly
   *    deactivates the elfcorehdr= kernel parameter
   */
  static __init void smp_save_cpu_vxrs(struct save_area *sa, u16 addr,
  				     bool is_boot_cpu, unsigned long page)
  {
  	__vector128 *vxrs = (__vector128 *) page;
  
  	if (is_boot_cpu)
  		vxrs = boot_cpu_vector_save_area;
  	else
  		__pcpu_sigp_relax(addr, SIGP_STORE_ADDITIONAL_STATUS, page);
  	save_area_add_vxrs(sa, vxrs);
  }
  
  static __init void smp_save_cpu_regs(struct save_area *sa, u16 addr,
  				     bool is_boot_cpu, unsigned long page)
  {
  	void *regs = (void *) page;
  
  	if (is_boot_cpu)
  		copy_oldmem_kernel(regs, (void *) __LC_FPREGS_SAVE_AREA, 512);
  	else
  		__pcpu_sigp_relax(addr, SIGP_STORE_STATUS_AT_ADDRESS, page);
  	save_area_add_regs(sa, regs);
  }
  
  void __init smp_save_dump_cpus(void)
  {
  	int addr, boot_cpu_addr, max_cpu_addr;
  	struct save_area *sa;
  	unsigned long page;
  	bool is_boot_cpu;
  
  	if (!(OLDMEM_BASE || ipl_info.type == IPL_TYPE_FCP_DUMP))
  		/* No previous system present, normal boot. */
  		return;
  	/* Allocate a page as dumping area for the store status sigps */
  	page = memblock_phys_alloc_range(PAGE_SIZE, PAGE_SIZE, 0, 1UL << 31);
  	if (!page)
  		panic("ERROR: Failed to allocate %lx bytes below %lx\n",
  		      PAGE_SIZE, 1UL << 31);
  
  	/* Set multi-threading state to the previous system. */
  	pcpu_set_smt(sclp.mtid_prev);
  	boot_cpu_addr = stap();
  	max_cpu_addr = SCLP_MAX_CORES << sclp.mtid_prev;
  	for (addr = 0; addr <= max_cpu_addr; addr++) {
  		if (__pcpu_sigp_relax(addr, SIGP_SENSE, 0) ==
  		    SIGP_CC_NOT_OPERATIONAL)
  			continue;
  		is_boot_cpu = (addr == boot_cpu_addr);
  		/* Allocate save area */
  		sa = save_area_alloc(is_boot_cpu);
  		if (!sa)
  			panic("could not allocate memory for save area\n");
  		if (MACHINE_HAS_VX)
  			/* Get the vector registers */
  			smp_save_cpu_vxrs(sa, addr, is_boot_cpu, page);
  		/*
  		 * For a zfcp dump OLDMEM_BASE == NULL and the registers
  		 * of the boot CPU are stored in the HSA. To retrieve
  		 * these registers an SCLP request is required which is
  		 * done by drivers/s390/char/zcore.c:init_cpu_info()
  		 */
  		if (!is_boot_cpu || OLDMEM_BASE)
  			/* Get the CPU registers */
  			smp_save_cpu_regs(sa, addr, is_boot_cpu, page);
  	}
  	memblock_free(page, PAGE_SIZE);
  	diag_dma_ops.diag308_reset();
  	pcpu_set_smt(0);
  }
  #endif /* CONFIG_CRASH_DUMP */
  
  void smp_cpu_set_polarization(int cpu, int val)
  {
  	pcpu_devices[cpu].polarization = val;
  }
  
  int smp_cpu_get_polarization(int cpu)
  {
  	return pcpu_devices[cpu].polarization;
  }
  
  static void __ref smp_get_core_info(struct sclp_core_info *info, int early)
  {
  	static int use_sigp_detection;
  	int address;
  
  	if (use_sigp_detection || sclp_get_core_info(info, early)) {
  		use_sigp_detection = 1;
  		for (address = 0;
  		     address < (SCLP_MAX_CORES << smp_cpu_mt_shift);
  		     address += (1U << smp_cpu_mt_shift)) {
  			if (__pcpu_sigp_relax(address, SIGP_SENSE, 0) ==
  			    SIGP_CC_NOT_OPERATIONAL)
  				continue;
  			info->core[info->configured].core_id =
  				address >> smp_cpu_mt_shift;
  			info->configured++;
  		}
  		info->combined = info->configured;
  	}
  }
  
  static int smp_add_present_cpu(int cpu);
  
  static int __smp_rescan_cpus(struct sclp_core_info *info, int sysfs_add)
  {
  	struct pcpu *pcpu;
  	cpumask_t avail;
  	int cpu, nr, i, j;
  	u16 address;
  
  	nr = 0;
  	cpumask_xor(&avail, cpu_possible_mask, cpu_present_mask);
  	cpu = cpumask_first(&avail);
  	for (i = 0; (i < info->combined) && (cpu < nr_cpu_ids); i++) {
  		if (sclp.has_core_type && info->core[i].type != boot_core_type)
  			continue;
  		address = info->core[i].core_id << smp_cpu_mt_shift;
  		for (j = 0; j <= smp_cpu_mtid; j++) {
  			if (pcpu_find_address(cpu_present_mask, address + j))
  				continue;
  			pcpu = pcpu_devices + cpu;
  			pcpu->address = address + j;
  			pcpu->state =
  				(cpu >= info->configured*(smp_cpu_mtid + 1)) ?
  				CPU_STATE_STANDBY : CPU_STATE_CONFIGURED;
  			smp_cpu_set_polarization(cpu, POLARIZATION_UNKNOWN);
  			set_cpu_present(cpu, true);
  			if (sysfs_add && smp_add_present_cpu(cpu) != 0)
  				set_cpu_present(cpu, false);
  			else
  				nr++;
  			cpu = cpumask_next(cpu, &avail);
  			if (cpu >= nr_cpu_ids)
  				break;
  		}
  	}
  	return nr;
  }
  
  void __init smp_detect_cpus(void)
  {
  	unsigned int cpu, mtid, c_cpus, s_cpus;
  	struct sclp_core_info *info;
  	u16 address;
  
  	/* Get CPU information */
  	info = memblock_alloc(sizeof(*info), 8);
  	if (!info)
  		panic("%s: Failed to allocate %zu bytes align=0x%x\n",
  		      __func__, sizeof(*info), 8);
  	smp_get_core_info(info, 1);
  	/* Find boot CPU type */
  	if (sclp.has_core_type) {
  		address = stap();
  		for (cpu = 0; cpu < info->combined; cpu++)
  			if (info->core[cpu].core_id == address) {
  				/* The boot cpu dictates the cpu type. */
  				boot_core_type = info->core[cpu].type;
  				break;
  			}
  		if (cpu >= info->combined)
  			panic("Could not find boot CPU type");
  	}
  
  	/* Set multi-threading state for the current system */
  	mtid = boot_core_type ? sclp.mtid : sclp.mtid_cp;
  	mtid = (mtid < smp_max_threads) ? mtid : smp_max_threads - 1;
  	pcpu_set_smt(mtid);
  
  	/* Print number of CPUs */
  	c_cpus = s_cpus = 0;
  	for (cpu = 0; cpu < info->combined; cpu++) {
  		if (sclp.has_core_type &&
  		    info->core[cpu].type != boot_core_type)
  			continue;
  		if (cpu < info->configured)
  			c_cpus += smp_cpu_mtid + 1;
  		else
  			s_cpus += smp_cpu_mtid + 1;
  	}
  	pr_info("%d configured CPUs, %d standby CPUs\n", c_cpus, s_cpus);
  
  	/* Add CPUs present at boot */
  	get_online_cpus();
  	__smp_rescan_cpus(info, 0);
  	put_online_cpus();
  	memblock_free_early((unsigned long)info, sizeof(*info));
  }
  
  static void smp_init_secondary(void)
  {
  	int cpu = smp_processor_id();
  
  	S390_lowcore.last_update_clock = get_tod_clock();
  	restore_access_regs(S390_lowcore.access_regs_save_area);
  	cpu_init();
  	preempt_disable();
  	init_cpu_timer();
  	vtime_init();
  	pfault_init();
  	notify_cpu_starting(smp_processor_id());
  	if (topology_cpu_dedicated(cpu))
  		set_cpu_flag(CIF_DEDICATED_CPU);
  	else
  		clear_cpu_flag(CIF_DEDICATED_CPU);
  	set_cpu_online(smp_processor_id(), true);
  	inc_irq_stat(CPU_RST);
  	local_irq_enable();
  	cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
  }
  
  /*
   *	Activate a secondary processor.
   */
  static void __no_sanitize_address smp_start_secondary(void *cpuvoid)
  {
  	S390_lowcore.restart_stack = (unsigned long) restart_stack;
  	S390_lowcore.restart_fn = (unsigned long) do_restart;
  	S390_lowcore.restart_data = 0;
  	S390_lowcore.restart_source = -1UL;
  	__ctl_load(S390_lowcore.cregs_save_area, 0, 15);
  	__load_psw_mask(PSW_KERNEL_BITS | PSW_MASK_DAT);
  	CALL_ON_STACK(smp_init_secondary, S390_lowcore.kernel_stack, 0);
  }
  
  /* Upping and downing of CPUs */
  int __cpu_up(unsigned int cpu, struct task_struct *tidle)
  {
  	struct pcpu *pcpu;
  	int base, i, rc;
  
  	pcpu = pcpu_devices + cpu;
  	if (pcpu->state != CPU_STATE_CONFIGURED)
  		return -EIO;
  	base = smp_get_base_cpu(cpu);
  	for (i = 0; i <= smp_cpu_mtid; i++) {
  		if (base + i < nr_cpu_ids)
  			if (cpu_online(base + i))
  				break;
  	}
  	/*
  	 * If this is the first CPU of the core to get online
  	 * do an initial CPU reset.
  	 */
  	if (i > smp_cpu_mtid &&
  	    pcpu_sigp_retry(pcpu_devices + base, SIGP_INITIAL_CPU_RESET, 0) !=
  	    SIGP_CC_ORDER_CODE_ACCEPTED)
  		return -EIO;
  
  	rc = pcpu_alloc_lowcore(pcpu, cpu);
  	if (rc)
  		return rc;
  	pcpu_prepare_secondary(pcpu, cpu);
  	pcpu_attach_task(pcpu, tidle);
  	pcpu_start_fn(pcpu, smp_start_secondary, NULL);
  	/* Wait until cpu puts itself in the online & active maps */
  	while (!cpu_online(cpu))
  		cpu_relax();
  	return 0;
  }
  
  static unsigned int setup_possible_cpus __initdata;
  
  static int __init _setup_possible_cpus(char *s)
  {
  	get_option(&s, &setup_possible_cpus);
  	return 0;
  }
  early_param("possible_cpus", _setup_possible_cpus);
  
  int __cpu_disable(void)
  {
  	unsigned long cregs[16];
  
  	/* Handle possible pending IPIs */
  	smp_handle_ext_call();
  	set_cpu_online(smp_processor_id(), false);
  	/* Disable pseudo page faults on this cpu. */
  	pfault_fini();
  	/* Disable interrupt sources via control register. */
  	__ctl_store(cregs, 0, 15);
  	cregs[0]  &= ~0x0000ee70UL;	/* disable all external interrupts */
  	cregs[6]  &= ~0xff000000UL;	/* disable all I/O interrupts */
  	cregs[14] &= ~0x1f000000UL;	/* disable most machine checks */
  	__ctl_load(cregs, 0, 15);
  	clear_cpu_flag(CIF_NOHZ_DELAY);
  	return 0;
  }
  
  void __cpu_die(unsigned int cpu)
  {
  	struct pcpu *pcpu;
  
  	/* Wait until target cpu is down */
  	pcpu = pcpu_devices + cpu;
  	while (!pcpu_stopped(pcpu))
  		cpu_relax();
  	pcpu_free_lowcore(pcpu);
  	cpumask_clear_cpu(cpu, mm_cpumask(&init_mm));
  	cpumask_clear_cpu(cpu, &init_mm.context.cpu_attach_mask);
  }
  
  void __noreturn cpu_die(void)
  {
  	idle_task_exit();
  	__bpon();
  	pcpu_sigp_retry(pcpu_devices + smp_processor_id(), SIGP_STOP, 0);
  	for (;;) ;
  }
  
  void __init smp_fill_possible_mask(void)
  {
  	unsigned int possible, sclp_max, cpu;
  
  	sclp_max = max(sclp.mtid, sclp.mtid_cp) + 1;
  	sclp_max = min(smp_max_threads, sclp_max);
  	sclp_max = (sclp.max_cores * sclp_max) ?: nr_cpu_ids;
  	possible = setup_possible_cpus ?: nr_cpu_ids;
  	possible = min(possible, sclp_max);
  	for (cpu = 0; cpu < possible && cpu < nr_cpu_ids; cpu++)
  		set_cpu_possible(cpu, true);
  }
  
  void __init smp_prepare_cpus(unsigned int max_cpus)
  {
  	/* request the 0x1201 emergency signal external interrupt */
  	if (register_external_irq(EXT_IRQ_EMERGENCY_SIG, do_ext_call_interrupt))
  		panic("Couldn't request external interrupt 0x1201");
  	/* request the 0x1202 external call external interrupt */
  	if (register_external_irq(EXT_IRQ_EXTERNAL_CALL, do_ext_call_interrupt))
  		panic("Couldn't request external interrupt 0x1202");
  }
  
  void __init smp_prepare_boot_cpu(void)
  {
  	struct pcpu *pcpu = pcpu_devices;
  
  	WARN_ON(!cpu_present(0) || !cpu_online(0));
  	pcpu->state = CPU_STATE_CONFIGURED;
  	pcpu->lowcore = (struct lowcore *)(unsigned long) store_prefix();
  	S390_lowcore.percpu_offset = __per_cpu_offset[0];
  	smp_cpu_set_polarization(0, POLARIZATION_UNKNOWN);
  }
  
  void __init smp_cpus_done(unsigned int max_cpus)
  {
  }
  
  void __init smp_setup_processor_id(void)
  {
  	pcpu_devices[0].address = stap();
  	S390_lowcore.cpu_nr = 0;
  	S390_lowcore.spinlock_lockval = arch_spin_lockval(0);
  	S390_lowcore.spinlock_index = 0;
  }
  
  /*
   * the frequency of the profiling timer can be changed
   * by writing a multiplier value into /proc/profile.
   *
   * usually you want to run this on all CPUs ;)
   */
  int setup_profiling_timer(unsigned int multiplier)
  {
  	return 0;
  }
  
  static ssize_t cpu_configure_show(struct device *dev,
  				  struct device_attribute *attr, char *buf)
  {
  	ssize_t count;
  
  	mutex_lock(&smp_cpu_state_mutex);
  	count = sprintf(buf, "%d\n", pcpu_devices[dev->id].state);
  	mutex_unlock(&smp_cpu_state_mutex);
  	return count;
  }
  
  static ssize_t cpu_configure_store(struct device *dev,
  				   struct device_attribute *attr,
  				   const char *buf, size_t count)
  {
  	struct pcpu *pcpu;
  	int cpu, val, rc, i;
  	char delim;
  
  	if (sscanf(buf, "%d %c", &val, &delim) != 1)
  		return -EINVAL;
  	if (val != 0 && val != 1)
  		return -EINVAL;
  	get_online_cpus();
  	mutex_lock(&smp_cpu_state_mutex);
  	rc = -EBUSY;
  	/* disallow configuration changes of online cpus and cpu 0 */
  	cpu = dev->id;
  	cpu = smp_get_base_cpu(cpu);
  	if (cpu == 0)
  		goto out;
  	for (i = 0; i <= smp_cpu_mtid; i++)
  		if (cpu_online(cpu + i))
  			goto out;
  	pcpu = pcpu_devices + cpu;
  	rc = 0;
  	switch (val) {
  	case 0:
  		if (pcpu->state != CPU_STATE_CONFIGURED)
  			break;
  		rc = sclp_core_deconfigure(pcpu->address >> smp_cpu_mt_shift);
  		if (rc)
  			break;
  		for (i = 0; i <= smp_cpu_mtid; i++) {
  			if (cpu + i >= nr_cpu_ids || !cpu_present(cpu + i))
  				continue;
  			pcpu[i].state = CPU_STATE_STANDBY;
  			smp_cpu_set_polarization(cpu + i,
  						 POLARIZATION_UNKNOWN);
  		}
  		topology_expect_change();
  		break;
  	case 1:
  		if (pcpu->state != CPU_STATE_STANDBY)
  			break;
  		rc = sclp_core_configure(pcpu->address >> smp_cpu_mt_shift);
  		if (rc)
  			break;
  		for (i = 0; i <= smp_cpu_mtid; i++) {
  			if (cpu + i >= nr_cpu_ids || !cpu_present(cpu + i))
  				continue;
  			pcpu[i].state = CPU_STATE_CONFIGURED;
  			smp_cpu_set_polarization(cpu + i,
  						 POLARIZATION_UNKNOWN);
  		}
  		topology_expect_change();
  		break;
  	default:
  		break;
  	}
  out:
  	mutex_unlock(&smp_cpu_state_mutex);
  	put_online_cpus();
  	return rc ? rc : count;
  }
  static DEVICE_ATTR(configure, 0644, cpu_configure_show, cpu_configure_store);
  
  static ssize_t show_cpu_address(struct device *dev,
  				struct device_attribute *attr, char *buf)
  {
  	return sprintf(buf, "%d\n", pcpu_devices[dev->id].address);
  }
  static DEVICE_ATTR(address, 0444, show_cpu_address, NULL);
  
  static struct attribute *cpu_common_attrs[] = {
  	&dev_attr_configure.attr,
  	&dev_attr_address.attr,
  	NULL,
  };
  
  static struct attribute_group cpu_common_attr_group = {
  	.attrs = cpu_common_attrs,
  };
  
  static struct attribute *cpu_online_attrs[] = {
  	&dev_attr_idle_count.attr,
  	&dev_attr_idle_time_us.attr,
  	NULL,
  };
  
  static struct attribute_group cpu_online_attr_group = {
  	.attrs = cpu_online_attrs,
  };
  
  static int smp_cpu_online(unsigned int cpu)
  {
  	struct device *s = &per_cpu(cpu_device, cpu)->dev;
  
  	return sysfs_create_group(&s->kobj, &cpu_online_attr_group);
  }
  static int smp_cpu_pre_down(unsigned int cpu)
  {
  	struct device *s = &per_cpu(cpu_device, cpu)->dev;
  
  	sysfs_remove_group(&s->kobj, &cpu_online_attr_group);
  	return 0;
  }
  
  static int smp_add_present_cpu(int cpu)
  {
  	struct device *s;
  	struct cpu *c;
  	int rc;
  
  	c = kzalloc(sizeof(*c), GFP_KERNEL);
  	if (!c)
  		return -ENOMEM;
  	per_cpu(cpu_device, cpu) = c;
  	s = &c->dev;
  	c->hotpluggable = 1;
  	rc = register_cpu(c, cpu);
  	if (rc)
  		goto out;
  	rc = sysfs_create_group(&s->kobj, &cpu_common_attr_group);
  	if (rc)
  		goto out_cpu;
  	rc = topology_cpu_init(c);
  	if (rc)
  		goto out_topology;
  	return 0;
  
  out_topology:
  	sysfs_remove_group(&s->kobj, &cpu_common_attr_group);
  out_cpu:
  	unregister_cpu(c);
  out:
  	return rc;
  }
  
  int __ref smp_rescan_cpus(void)
  {
  	struct sclp_core_info *info;
  	int nr;
  
  	info = kzalloc(sizeof(*info), GFP_KERNEL);
  	if (!info)
  		return -ENOMEM;
  	smp_get_core_info(info, 0);
  	get_online_cpus();
  	mutex_lock(&smp_cpu_state_mutex);
  	nr = __smp_rescan_cpus(info, 1);
  	mutex_unlock(&smp_cpu_state_mutex);
  	put_online_cpus();
  	kfree(info);
  	if (nr)
  		topology_schedule_update();
  	return 0;
  }
  
  static ssize_t __ref rescan_store(struct device *dev,
  				  struct device_attribute *attr,
  				  const char *buf,
  				  size_t count)
  {
  	int rc;
  
  	rc = lock_device_hotplug_sysfs();
  	if (rc)
  		return rc;
  	rc = smp_rescan_cpus();
  	unlock_device_hotplug();
  	return rc ? rc : count;
  }
  static DEVICE_ATTR_WO(rescan);
  
  static int __init s390_smp_init(void)
  {
  	int cpu, rc = 0;
  
  	rc = device_create_file(cpu_subsys.dev_root, &dev_attr_rescan);
  	if (rc)
  		return rc;
  	for_each_present_cpu(cpu) {
  		rc = smp_add_present_cpu(cpu);
  		if (rc)
  			goto out;
  	}
  
  	rc = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "s390/smp:online",
  			       smp_cpu_online, smp_cpu_pre_down);
  	rc = rc <= 0 ? rc : 0;
  out:
  	return rc;
  }
  subsys_initcall(s390_smp_init);
  