arch/x86/kernel/cpu/topology.c - pub/scm/linux/kernel/git/geert/linux-m68k - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * CPU/APIC topology
  *
  * The APIC IDs describe the system topology in multiple domain levels.
  * The CPUID topology parser provides the information which part of the
  * APIC ID is associated to the individual levels:
  *
  * [PACKAGE][DIEGRP][DIE][TILE][MODULE][CORE][THREAD]
  *
  * The root space contains the package (socket) IDs.
  *
  * Not enumerated levels consume 0 bits space, but conceptually they are
  * always represented. If e.g. only CORE and THREAD levels are enumerated
  * then the DIE, MODULE and TILE have the same physical ID as the PACKAGE.
  *
  * If SMT is not supported, then the THREAD domain is still used. It then
  * has the same physical ID as the CORE domain and is the only child of
  * the core domain.
  *
  * This allows a unified view on the system independent of the enumerated
  * domain levels without requiring any conditionals in the code.
  */
 #define pr_fmt(fmt) "CPU topo: " fmt
 #include <linux/cpu.h>

 #include <xen/xen.h>

 #include <asm/apic.h>
 #include <asm/hypervisor.h>
 #include <asm/io_apic.h>
 #include <asm/mpspec.h>
 #include <asm/smp.h>

 #include "cpu.h"

 /*
  * Map cpu index to physical APIC ID
  */
 DEFINE_EARLY_PER_CPU_READ_MOSTLY(u32, x86_cpu_to_apicid, BAD_APICID);
 DEFINE_EARLY_PER_CPU_READ_MOSTLY(u32, x86_cpu_to_acpiid, CPU_ACPIID_INVALID);
 EXPORT_EARLY_PER_CPU_SYMBOL(x86_cpu_to_apicid);
 EXPORT_EARLY_PER_CPU_SYMBOL(x86_cpu_to_acpiid);

 /* Bitmap of physically present CPUs. */
 DECLARE_BITMAP(phys_cpu_present_map, MAX_LOCAL_APIC) __read_mostly;

 /* Used for CPU number allocation and parallel CPU bringup */
 u32 cpuid_to_apicid[] __ro_after_init = { [0 ... NR_CPUS - 1] = BAD_APICID, };

 /* Bitmaps to mark registered APICs at each topology domain */
 static struct { DECLARE_BITMAP(map, MAX_LOCAL_APIC); } apic_maps[TOPO_MAX_DOMAIN] __ro_after_init;

 /*
  * Keep track of assigned, disabled and rejected CPUs. Present assigned
  * with 1 as CPU #0 is reserved for the boot CPU.
  */
 static struct {
 	unsigned int		nr_assigned_cpus;
 	unsigned int		nr_disabled_cpus;
 	unsigned int		nr_rejected_cpus;
 	u32			boot_cpu_apic_id;
 	u32			real_bsp_apic_id;
 } topo_info __ro_after_init = {
 	.nr_assigned_cpus	= 1,
 	.boot_cpu_apic_id	= BAD_APICID,
 	.real_bsp_apic_id	= BAD_APICID,
 };

 #define domain_weight(_dom)	bitmap_weight(apic_maps[_dom].map, MAX_LOCAL_APIC)

 bool arch_match_cpu_phys_id(int cpu, u64 phys_id)
 {
 	return phys_id == (u64)cpuid_to_apicid[cpu];
 }

 #ifdef CONFIG_SMP
 static void cpu_mark_primary_thread(unsigned int cpu, unsigned int apicid)
 {
 	if (!(apicid & (__max_threads_per_core - 1)))
 		cpumask_set_cpu(cpu, &__cpu_primary_thread_mask);
 }
 #else
 static inline void cpu_mark_primary_thread(unsigned int cpu, unsigned int apicid) { }
 #endif

 /*
  * Convert the APIC ID to a domain level ID by masking out the low bits
  * below the domain level @dom.
  */
 static inline u32 topo_apicid(u32 apicid, enum x86_topology_domains dom)
 {
 	if (dom == TOPO_SMT_DOMAIN)
 		return apicid;
 	return apicid & (UINT_MAX << x86_topo_system.dom_shifts[dom - 1]);
 }

 static int topo_lookup_cpuid(u32 apic_id)
 {
 	int i;

 	/* CPU# to APICID mapping is persistent once it is established */
 	for (i = 0; i < topo_info.nr_assigned_cpus; i++) {
 		if (cpuid_to_apicid[i] == apic_id)
 			return i;
 	}
 	return -ENODEV;
 }

 static __init int topo_get_cpunr(u32 apic_id)
 {
 	int cpu = topo_lookup_cpuid(apic_id);

 	if (cpu >= 0)
 		return cpu;

 	return topo_info.nr_assigned_cpus++;
 }

 static void topo_set_cpuids(unsigned int cpu, u32 apic_id, u32 acpi_id)
 {
 #if defined(CONFIG_SMP) || defined(CONFIG_X86_64)
 	early_per_cpu(x86_cpu_to_apicid, cpu) = apic_id;
 	early_per_cpu(x86_cpu_to_acpiid, cpu) = acpi_id;
 #endif
 	set_cpu_possible(cpu, true);
 	set_cpu_present(cpu, true);
 }

 static __init bool check_for_real_bsp(u32 apic_id)
 {
 	/*
 	 * There is no real good way to detect whether this a kdump()
 	 * kernel, but except on the Voyager SMP monstrosity which is not
 	 * longer supported, the real BSP APIC ID is the first one which is
 	 * enumerated by firmware. That allows to detect whether the boot
 	 * CPU is the real BSP. If it is not, then do not register the APIC
 	 * because sending INIT to the real BSP would reset the whole
 	 * system.
 	 *
 	 * The first APIC ID which is enumerated by firmware is detectable
 	 * because the boot CPU APIC ID is registered before that without
 	 * invoking this code.
 	 */
 	if (topo_info.real_bsp_apic_id != BAD_APICID)
 		return false;

 	if (apic_id == topo_info.boot_cpu_apic_id) {
 		topo_info.real_bsp_apic_id = apic_id;
 		return false;
 	}

 	pr_warn("Boot CPU APIC ID not the first enumerated APIC ID: %x > %x\n",
 		topo_info.boot_cpu_apic_id, apic_id);
 	pr_warn("Crash kernel detected. Disabling real BSP to prevent machine INIT\n");

 	topo_info.real_bsp_apic_id = apic_id;
 	return true;
 }

 static unsigned int topo_unit_count(u32 lvlid, enum x86_topology_domains at_level,
 				    unsigned long *map)
 {
 	unsigned int id, end, cnt = 0;

 	/* Calculate the exclusive end */
 	end = lvlid + (1U << x86_topo_system.dom_shifts[at_level]);

 	/* Unfortunately there is no bitmap_weight_range() */
 	for (id = find_next_bit(map, end, lvlid); id < end; id = find_next_bit(map, end, ++id))
 		cnt++;
 	return cnt;
 }

 static __init void topo_register_apic(u32 apic_id, u32 acpi_id, bool present)
 {
 	int cpu, dom;

 	if (present) {
 		set_bit(apic_id, phys_cpu_present_map);

 		/*
 		 * Double registration is valid in case of the boot CPU
 		 * APIC because that is registered before the enumeration
 		 * of the APICs via firmware parsers or VM guest
 		 * mechanisms.
 		 */
 		if (apic_id == topo_info.boot_cpu_apic_id)
 			cpu = 0;
 		else
 			cpu = topo_get_cpunr(apic_id);

 		cpuid_to_apicid[cpu] = apic_id;
 		topo_set_cpuids(cpu, apic_id, acpi_id);
 	} else {
 		u32 pkgid = topo_apicid(apic_id, TOPO_PKG_DOMAIN);

 		/*
 		 * Check for present APICs in the same package when running
 		 * on bare metal. Allow the bogosity in a guest.
 		 */
 		if (hypervisor_is_type(X86_HYPER_NATIVE) &&
 		    topo_unit_count(pkgid, TOPO_PKG_DOMAIN, phys_cpu_present_map)) {
 			pr_info_once("Ignoring hot-pluggable APIC ID %x in present package.\n",
 				     apic_id);
 			topo_info.nr_rejected_cpus++;
 			return;
 		}

 		topo_info.nr_disabled_cpus++;
 	}

 	/* Register present and possible CPUs in the domain maps */
 	for (dom = TOPO_SMT_DOMAIN; dom < TOPO_MAX_DOMAIN; dom++)
 		set_bit(topo_apicid(apic_id, dom), apic_maps[dom].map);
 }

 /**
  * topology_register_apic - Register an APIC in early topology maps
  * @apic_id:	The APIC ID to set up
  * @acpi_id:	The ACPI ID associated to the APIC
  * @present:	True if the corresponding CPU is present
  */
 void __init topology_register_apic(u32 apic_id, u32 acpi_id, bool present)
 {
 	if (apic_id >= MAX_LOCAL_APIC) {
 		pr_err_once("APIC ID %x exceeds kernel limit of: %x\n", apic_id, MAX_LOCAL_APIC - 1);
 		topo_info.nr_rejected_cpus++;
 		return;
 	}

 	if (check_for_real_bsp(apic_id)) {
 		topo_info.nr_rejected_cpus++;
 		return;
 	}

 	/* CPU numbers exhausted? */
 	if (apic_id != topo_info.boot_cpu_apic_id && topo_info.nr_assigned_cpus >= nr_cpu_ids) {
 		pr_warn_once("CPU limit of %d reached. Ignoring further CPUs\n", nr_cpu_ids);
 		topo_info.nr_rejected_cpus++;
 		return;
 	}

 	topo_register_apic(apic_id, acpi_id, present);
 }

 /**
  * topology_register_boot_apic - Register the boot CPU APIC
  * @apic_id:	The APIC ID to set up
  *
  * Separate so CPU #0 can be assigned
  */
 void __init topology_register_boot_apic(u32 apic_id)
 {
 	WARN_ON_ONCE(topo_info.boot_cpu_apic_id != BAD_APICID);

 	topo_info.boot_cpu_apic_id = apic_id;
 	topo_register_apic(apic_id, CPU_ACPIID_INVALID, true);
 }

 /**
  * topology_get_logical_id - Retrieve the logical ID at a given topology domain level
  * @apicid:		The APIC ID for which to lookup the logical ID
  * @at_level:		The topology domain level to use
  *
  * @apicid must be a full APIC ID, not the normalized variant. It's valid to have
  * all bits below the domain level specified by @at_level to be clear. So both
  * real APIC IDs and backshifted normalized APIC IDs work correctly.
  *
  * Returns:
  *  - >= 0:	The requested logical ID
  *  - -ERANGE:	@apicid is out of range
  *  - -ENODEV:	@apicid is not registered
  */
 int topology_get_logical_id(u32 apicid, enum x86_topology_domains at_level)
 {
 	/* Remove the bits below @at_level to get the proper level ID of @apicid */
 	unsigned int lvlid = topo_apicid(apicid, at_level);

 	if (lvlid >= MAX_LOCAL_APIC)
 		return -ERANGE;
 	if (!test_bit(lvlid, apic_maps[at_level].map))
 		return -ENODEV;
 	/* Get the number of set bits before @lvlid. */
 	return bitmap_weight(apic_maps[at_level].map, lvlid);
 }
 EXPORT_SYMBOL_GPL(topology_get_logical_id);

 /**
  * topology_unit_count - Retrieve the count of specified units at a given topology domain level
  * @apicid:		The APIC ID which specifies the search range
  * @which_units:	The domain level specifying the units to count
  * @at_level:		The domain level at which @which_units have to be counted
  *
  * This returns the number of possible units according to the enumerated
  * information.
  *
  * E.g. topology_count_units(apicid, TOPO_CORE_DOMAIN, TOPO_PKG_DOMAIN)
  * counts the number of possible cores in the package to which @apicid
  * belongs.
  *
  * @at_level must obviously be greater than @which_level to produce useful
  * results.  If @at_level is equal to @which_units the result is
  * unsurprisingly 1. If @at_level is less than @which_units the results
  * is by definition undefined and the function returns 0.
  */
 unsigned int topology_unit_count(u32 apicid, enum x86_topology_domains which_units,
 				 enum x86_topology_domains at_level)
 {
 	/* Remove the bits below @at_level to get the proper level ID of @apicid */
 	unsigned int lvlid = topo_apicid(apicid, at_level);

 	if (lvlid >= MAX_LOCAL_APIC)
 		return 0;
 	if (!test_bit(lvlid, apic_maps[at_level].map))
 		return 0;
 	if (which_units > at_level)
 		return 0;
 	if (which_units == at_level)
 		return 1;
 	return topo_unit_count(lvlid, at_level, apic_maps[which_units].map);
 }

 #ifdef CONFIG_ACPI_HOTPLUG_CPU
 /**
  * topology_hotplug_apic - Handle a physical hotplugged APIC after boot
  * @apic_id:	The APIC ID to set up
  * @acpi_id:	The ACPI ID associated to the APIC
  */
 int topology_hotplug_apic(u32 apic_id, u32 acpi_id)
 {
 	int cpu;

 	if (apic_id >= MAX_LOCAL_APIC)
 		return -EINVAL;

 	/* Reject if the APIC ID was not registered during enumeration. */
 	if (!test_bit(apic_id, apic_maps[TOPO_SMT_DOMAIN].map))
 		return -ENODEV;

 	cpu = topo_lookup_cpuid(apic_id);
 	if (cpu < 0)
 		return -ENOSPC;

 	set_bit(apic_id, phys_cpu_present_map);
 	topo_set_cpuids(cpu, apic_id, acpi_id);
 	cpu_mark_primary_thread(cpu, apic_id);
 	return cpu;
 }

 /**
  * topology_hotunplug_apic - Remove a physical hotplugged APIC after boot
  * @cpu:	The CPU number for which the APIC ID is removed
  */
 void topology_hotunplug_apic(unsigned int cpu)
 {
 	u32 apic_id = cpuid_to_apicid[cpu];

 	if (apic_id == BAD_APICID)
 		return;

 	per_cpu(x86_cpu_to_apicid, cpu) = BAD_APICID;
 	clear_bit(apic_id, phys_cpu_present_map);
 	set_cpu_present(cpu, false);
 }
 #endif

 #ifdef CONFIG_X86_LOCAL_APIC
 static unsigned int max_possible_cpus __initdata = NR_CPUS;

 /**
  * topology_apply_cmdline_limits_early - Apply topology command line limits early
  *
  * Ensure that command line limits are in effect before firmware parsing
  * takes place.
  */
 void __init topology_apply_cmdline_limits_early(void)
 {
 	unsigned int possible = nr_cpu_ids;

 	/* 'maxcpus=0' 'nosmp' 'nolapic' 'disableapic' 'noapic' */
 	if (!setup_max_cpus || ioapic_is_disabled || apic_is_disabled)
 		possible = 1;

 	/* 'possible_cpus=N' */
 	possible = min_t(unsigned int, max_possible_cpus, possible);

 	if (possible < nr_cpu_ids) {
 		pr_info("Limiting to %u possible CPUs\n", possible);
 		set_nr_cpu_ids(possible);
 	}
 }

 static __init bool restrict_to_up(void)
 {
 	if (!smp_found_config || ioapic_is_disabled)
 		return true;
 	/*
 	 * XEN PV is special as it does not advertise the local APIC
 	 * properly, but provides a fake topology for it so that the
 	 * infrastructure works. So don't apply the restrictions vs. APIC
 	 * here.
 	 */
 	if (xen_pv_domain())
 		return false;

 	return apic_is_disabled;
 }

 void __init topology_init_possible_cpus(void)
 {
 	unsigned int assigned = topo_info.nr_assigned_cpus;
 	unsigned int disabled = topo_info.nr_disabled_cpus;
 	unsigned int cnta, cntb, cpu, allowed = 1;
 	unsigned int total = assigned + disabled;
 	u32 apicid, firstid;

 	/*
 	 * If there was no APIC registered, then fake one so that the
 	 * topology bitmap is populated. That ensures that the code below
 	 * is valid and the various query interfaces can be used
 	 * unconditionally. This does not affect the actual APIC code in
 	 * any way because either the local APIC address has not been
 	 * registered or the local APIC was disabled on the command line.
 	 */
 	if (topo_info.boot_cpu_apic_id == BAD_APICID)
 		topology_register_boot_apic(0);

 	if (!restrict_to_up()) {
 		if (WARN_ON_ONCE(assigned > nr_cpu_ids)) {
 			disabled += assigned - nr_cpu_ids;
 			assigned = nr_cpu_ids;
 		}
 		allowed = min_t(unsigned int, total, nr_cpu_ids);
 	}

 	if (total > allowed)
 		pr_warn("%u possible CPUs exceed the limit of %u\n", total, allowed);

 	assigned = min_t(unsigned int, allowed, assigned);
 	disabled = allowed - assigned;

 	topo_info.nr_assigned_cpus = assigned;
 	topo_info.nr_disabled_cpus = disabled;

 	total_cpus = allowed;
 	set_nr_cpu_ids(allowed);

 	cnta = domain_weight(TOPO_PKG_DOMAIN);
 	cntb = domain_weight(TOPO_DIE_DOMAIN);
 	__max_logical_packages = cnta;
 	__max_dies_per_package = 1U << (get_count_order(cntb) - get_count_order(cnta));

 	pr_info("Max. logical packages: %3u\n", cnta);
 	pr_info("Max. logical dies:     %3u\n", cntb);
 	pr_info("Max. dies per package: %3u\n", __max_dies_per_package);

 	cnta = domain_weight(TOPO_CORE_DOMAIN);
 	cntb = domain_weight(TOPO_SMT_DOMAIN);
 	/*
 	 * Can't use order delta here as order(cnta) can be equal
 	 * order(cntb) even if cnta != cntb.
 	 */
 	__max_threads_per_core = DIV_ROUND_UP(cntb, cnta);
 	pr_info("Max. threads per core: %3u\n", __max_threads_per_core);

 	firstid = find_first_bit(apic_maps[TOPO_SMT_DOMAIN].map, MAX_LOCAL_APIC);
 	__num_cores_per_package = topology_unit_count(firstid, TOPO_CORE_DOMAIN, TOPO_PKG_DOMAIN);
 	pr_info("Num. cores per package:   %3u\n", __num_cores_per_package);
 	__num_threads_per_package = topology_unit_count(firstid, TOPO_SMT_DOMAIN, TOPO_PKG_DOMAIN);
 	pr_info("Num. threads per package: %3u\n", __num_threads_per_package);

 	pr_info("Allowing %u present CPUs plus %u hotplug CPUs\n", assigned, disabled);
 	if (topo_info.nr_rejected_cpus)
 		pr_info("Rejected CPUs %u\n", topo_info.nr_rejected_cpus);

 	init_cpu_present(cpumask_of(0));
 	init_cpu_possible(cpumask_of(0));

 	/* Assign CPU numbers to non-present CPUs */
 	for (apicid = 0; disabled; disabled--, apicid++) {
 		apicid = find_next_andnot_bit(apic_maps[TOPO_SMT_DOMAIN].map, phys_cpu_present_map,
 					      MAX_LOCAL_APIC, apicid);
 		if (apicid >= MAX_LOCAL_APIC)
 			break;
 		cpuid_to_apicid[topo_info.nr_assigned_cpus++] = apicid;
 	}

 	for (cpu = 0; cpu < allowed; cpu++) {
 		apicid = cpuid_to_apicid[cpu];

 		set_cpu_possible(cpu, true);

 		if (apicid == BAD_APICID)
 			continue;

 		cpu_mark_primary_thread(cpu, apicid);
 		set_cpu_present(cpu, test_bit(apicid, phys_cpu_present_map));
 	}
 }

 /*
  * Late SMP disable after sizing CPU masks when APIC/IOAPIC setup failed.
  */
 void __init topology_reset_possible_cpus_up(void)
 {
 	init_cpu_present(cpumask_of(0));
 	init_cpu_possible(cpumask_of(0));

 	bitmap_zero(phys_cpu_present_map, MAX_LOCAL_APIC);
 	if (topo_info.boot_cpu_apic_id != BAD_APICID)
 		set_bit(topo_info.boot_cpu_apic_id, phys_cpu_present_map);
 }

 static int __init setup_possible_cpus(char *str)
 {
 	get_option(&str, &max_possible_cpus);
 	return 0;
 }
 early_param("possible_cpus", setup_possible_cpus);
 #endif
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* CPU/APIC topology
	*
	* The APIC IDs describe the system topology in multiple domain levels.
	* The CPUID topology parser provides the information which part of the
	* APIC ID is associated to the individual levels:
	*
	* [PACKAGE][DIEGRP][DIE][TILE][MODULE][CORE][THREAD]
	*
	* The root space contains the package (socket) IDs.
	*
	* Not enumerated levels consume 0 bits space, but conceptually they are
	* always represented. If e.g. only CORE and THREAD levels are enumerated
	* then the DIE, MODULE and TILE have the same physical ID as the PACKAGE.
	*
	* If SMT is not supported, then the THREAD domain is still used. It then
	* has the same physical ID as the CORE domain and is the only child of
	* the core domain.
	*
	* This allows a unified view on the system independent of the enumerated
	* domain levels without requiring any conditionals in the code.
	*/
	#define pr_fmt(fmt) "CPU topo: " fmt
	#include <linux/cpu.h>

	#include <xen/xen.h>

	#include <asm/apic.h>
	#include <asm/hypervisor.h>
	#include <asm/io_apic.h>
	#include <asm/mpspec.h>
	#include <asm/smp.h>

	#include "cpu.h"

	/*
	* Map cpu index to physical APIC ID
	*/
	DEFINE_EARLY_PER_CPU_READ_MOSTLY(u32, x86_cpu_to_apicid, BAD_APICID);
	DEFINE_EARLY_PER_CPU_READ_MOSTLY(u32, x86_cpu_to_acpiid, CPU_ACPIID_INVALID);
	EXPORT_EARLY_PER_CPU_SYMBOL(x86_cpu_to_apicid);
	EXPORT_EARLY_PER_CPU_SYMBOL(x86_cpu_to_acpiid);

	/* Bitmap of physically present CPUs. */
	DECLARE_BITMAP(phys_cpu_present_map, MAX_LOCAL_APIC) __read_mostly;

	/* Used for CPU number allocation and parallel CPU bringup */
	u32 cpuid_to_apicid[] __ro_after_init = { [0 ... NR_CPUS - 1] = BAD_APICID, };

	/* Bitmaps to mark registered APICs at each topology domain */
	static struct { DECLARE_BITMAP(map, MAX_LOCAL_APIC); } apic_maps[TOPO_MAX_DOMAIN] __ro_after_init;

	/*
	* Keep track of assigned, disabled and rejected CPUs. Present assigned
	* with 1 as CPU #0 is reserved for the boot CPU.
	*/
	static struct {
	unsigned int nr_assigned_cpus;
	unsigned int nr_disabled_cpus;
	unsigned int nr_rejected_cpus;
	u32 boot_cpu_apic_id;
	u32 real_bsp_apic_id;
	} topo_info __ro_after_init = {
	.nr_assigned_cpus = 1,
	.boot_cpu_apic_id = BAD_APICID,
	.real_bsp_apic_id = BAD_APICID,
	};

	#define domain_weight(_dom) bitmap_weight(apic_maps[_dom].map, MAX_LOCAL_APIC)

	bool arch_match_cpu_phys_id(int cpu, u64 phys_id)
	{
	return phys_id == (u64)cpuid_to_apicid[cpu];
	}

	#ifdef CONFIG_SMP
	static void cpu_mark_primary_thread(unsigned int cpu, unsigned int apicid)
	{
	if (!(apicid & (__max_threads_per_core - 1)))
	cpumask_set_cpu(cpu, &__cpu_primary_thread_mask);
	}
	#else
	static inline void cpu_mark_primary_thread(unsigned int cpu, unsigned int apicid) { }
	#endif

	/*
	* Convert the APIC ID to a domain level ID by masking out the low bits
	* below the domain level @dom.
	*/
	static inline u32 topo_apicid(u32 apicid, enum x86_topology_domains dom)
	{
	if (dom == TOPO_SMT_DOMAIN)
	return apicid;
	return apicid & (UINT_MAX << x86_topo_system.dom_shifts[dom - 1]);
	}

	static int topo_lookup_cpuid(u32 apic_id)
	{
	int i;

	/* CPU# to APICID mapping is persistent once it is established */
	for (i = 0; i < topo_info.nr_assigned_cpus; i++) {
	if (cpuid_to_apicid[i] == apic_id)
	return i;
	}
	return -ENODEV;
	}

	static __init int topo_get_cpunr(u32 apic_id)
	{
	int cpu = topo_lookup_cpuid(apic_id);

	if (cpu >= 0)
	return cpu;

	return topo_info.nr_assigned_cpus++;
	}

	static void topo_set_cpuids(unsigned int cpu, u32 apic_id, u32 acpi_id)
	{
	#if defined(CONFIG_SMP) \|\| defined(CONFIG_X86_64)
	early_per_cpu(x86_cpu_to_apicid, cpu) = apic_id;
	early_per_cpu(x86_cpu_to_acpiid, cpu) = acpi_id;
	#endif
	set_cpu_possible(cpu, true);
	set_cpu_present(cpu, true);
	}

	static __init bool check_for_real_bsp(u32 apic_id)
	{
	/*
	* There is no real good way to detect whether this a kdump()
	* kernel, but except on the Voyager SMP monstrosity which is not
	* longer supported, the real BSP APIC ID is the first one which is
	* enumerated by firmware. That allows to detect whether the boot
	* CPU is the real BSP. If it is not, then do not register the APIC
	* because sending INIT to the real BSP would reset the whole
	* system.
	*
	* The first APIC ID which is enumerated by firmware is detectable
	* because the boot CPU APIC ID is registered before that without
	* invoking this code.
	*/
	if (topo_info.real_bsp_apic_id != BAD_APICID)
	return false;

	if (apic_id == topo_info.boot_cpu_apic_id) {
	topo_info.real_bsp_apic_id = apic_id;
	return false;
	}

	pr_warn("Boot CPU APIC ID not the first enumerated APIC ID: %x > %x\n",
	topo_info.boot_cpu_apic_id, apic_id);
	pr_warn("Crash kernel detected. Disabling real BSP to prevent machine INIT\n");

	topo_info.real_bsp_apic_id = apic_id;
	return true;
	}

	static unsigned int topo_unit_count(u32 lvlid, enum x86_topology_domains at_level,
	unsigned long *map)
	{
	unsigned int id, end, cnt = 0;

	/* Calculate the exclusive end */
	end = lvlid + (1U << x86_topo_system.dom_shifts[at_level]);

	/* Unfortunately there is no bitmap_weight_range() */
	for (id = find_next_bit(map, end, lvlid); id < end; id = find_next_bit(map, end, ++id))
	cnt++;
	return cnt;
	}

	static __init void topo_register_apic(u32 apic_id, u32 acpi_id, bool present)
	{
	int cpu, dom;

	if (present) {
	set_bit(apic_id, phys_cpu_present_map);

	/*
	* Double registration is valid in case of the boot CPU
	* APIC because that is registered before the enumeration
	* of the APICs via firmware parsers or VM guest
	* mechanisms.
	*/
	if (apic_id == topo_info.boot_cpu_apic_id)
	cpu = 0;
	else
	cpu = topo_get_cpunr(apic_id);

	cpuid_to_apicid[cpu] = apic_id;
	topo_set_cpuids(cpu, apic_id, acpi_id);
	} else {
	u32 pkgid = topo_apicid(apic_id, TOPO_PKG_DOMAIN);

	/*
	* Check for present APICs in the same package when running
	* on bare metal. Allow the bogosity in a guest.
	*/
	if (hypervisor_is_type(X86_HYPER_NATIVE) &&
	topo_unit_count(pkgid, TOPO_PKG_DOMAIN, phys_cpu_present_map)) {
	pr_info_once("Ignoring hot-pluggable APIC ID %x in present package.\n",
	apic_id);
	topo_info.nr_rejected_cpus++;
	return;
	}

	topo_info.nr_disabled_cpus++;
	}

	/* Register present and possible CPUs in the domain maps */
	for (dom = TOPO_SMT_DOMAIN; dom < TOPO_MAX_DOMAIN; dom++)
	set_bit(topo_apicid(apic_id, dom), apic_maps[dom].map);
	}

	/**
	* topology_register_apic - Register an APIC in early topology maps
	* @apic_id: The APIC ID to set up
	* @acpi_id: The ACPI ID associated to the APIC
	* @present: True if the corresponding CPU is present
	*/
	void __init topology_register_apic(u32 apic_id, u32 acpi_id, bool present)
	{
	if (apic_id >= MAX_LOCAL_APIC) {
	pr_err_once("APIC ID %x exceeds kernel limit of: %x\n", apic_id, MAX_LOCAL_APIC - 1);
	topo_info.nr_rejected_cpus++;
	return;
	}

	if (check_for_real_bsp(apic_id)) {
	topo_info.nr_rejected_cpus++;
	return;
	}

	/* CPU numbers exhausted? */
	if (apic_id != topo_info.boot_cpu_apic_id && topo_info.nr_assigned_cpus >= nr_cpu_ids) {
	pr_warn_once("CPU limit of %d reached. Ignoring further CPUs\n", nr_cpu_ids);
	topo_info.nr_rejected_cpus++;
	return;
	}

	topo_register_apic(apic_id, acpi_id, present);
	}

	/**
	* topology_register_boot_apic - Register the boot CPU APIC
	* @apic_id: The APIC ID to set up
	*
	* Separate so CPU #0 can be assigned
	*/
	void __init topology_register_boot_apic(u32 apic_id)
	{
	WARN_ON_ONCE(topo_info.boot_cpu_apic_id != BAD_APICID);

	topo_info.boot_cpu_apic_id = apic_id;
	topo_register_apic(apic_id, CPU_ACPIID_INVALID, true);
	}

	/**
	* topology_get_logical_id - Retrieve the logical ID at a given topology domain level
	* @apicid: The APIC ID for which to lookup the logical ID
	* @at_level: The topology domain level to use
	*
	* @apicid must be a full APIC ID, not the normalized variant. It's valid to have
	* all bits below the domain level specified by @at_level to be clear. So both
	* real APIC IDs and backshifted normalized APIC IDs work correctly.
	*
	* Returns:
	* - >= 0: The requested logical ID
	* - -ERANGE: @apicid is out of range
	* - -ENODEV: @apicid is not registered
	*/
	int topology_get_logical_id(u32 apicid, enum x86_topology_domains at_level)
	{
	/* Remove the bits below @at_level to get the proper level ID of @apicid */
	unsigned int lvlid = topo_apicid(apicid, at_level);

	if (lvlid >= MAX_LOCAL_APIC)
	return -ERANGE;
	if (!test_bit(lvlid, apic_maps[at_level].map))
	return -ENODEV;
	/* Get the number of set bits before @lvlid. */
	return bitmap_weight(apic_maps[at_level].map, lvlid);
	}
	EXPORT_SYMBOL_GPL(topology_get_logical_id);

	/**
	* topology_unit_count - Retrieve the count of specified units at a given topology domain level
	* @apicid: The APIC ID which specifies the search range
	* @which_units: The domain level specifying the units to count
	* @at_level: The domain level at which @which_units have to be counted
	*
	* This returns the number of possible units according to the enumerated
	* information.
	*
	* E.g. topology_count_units(apicid, TOPO_CORE_DOMAIN, TOPO_PKG_DOMAIN)
	* counts the number of possible cores in the package to which @apicid
	* belongs.
	*
	* @at_level must obviously be greater than @which_level to produce useful
	* results. If @at_level is equal to @which_units the result is
	* unsurprisingly 1. If @at_level is less than @which_units the results
	* is by definition undefined and the function returns 0.
	*/
	unsigned int topology_unit_count(u32 apicid, enum x86_topology_domains which_units,
	enum x86_topology_domains at_level)
	{
	/* Remove the bits below @at_level to get the proper level ID of @apicid */
	unsigned int lvlid = topo_apicid(apicid, at_level);

	if (lvlid >= MAX_LOCAL_APIC)
	return 0;
	if (!test_bit(lvlid, apic_maps[at_level].map))
	return 0;
	if (which_units > at_level)
	return 0;
	if (which_units == at_level)
	return 1;
	return topo_unit_count(lvlid, at_level, apic_maps[which_units].map);
	}

	#ifdef CONFIG_ACPI_HOTPLUG_CPU
	/**
	* topology_hotplug_apic - Handle a physical hotplugged APIC after boot
	* @apic_id: The APIC ID to set up
	* @acpi_id: The ACPI ID associated to the APIC
	*/
	int topology_hotplug_apic(u32 apic_id, u32 acpi_id)
	{
	int cpu;

	if (apic_id >= MAX_LOCAL_APIC)
	return -EINVAL;

	/* Reject if the APIC ID was not registered during enumeration. */
	if (!test_bit(apic_id, apic_maps[TOPO_SMT_DOMAIN].map))
	return -ENODEV;

	cpu = topo_lookup_cpuid(apic_id);
	if (cpu < 0)
	return -ENOSPC;

	set_bit(apic_id, phys_cpu_present_map);
	topo_set_cpuids(cpu, apic_id, acpi_id);
	cpu_mark_primary_thread(cpu, apic_id);
	return cpu;
	}

	/**
	* topology_hotunplug_apic - Remove a physical hotplugged APIC after boot
	* @cpu: The CPU number for which the APIC ID is removed
	*/
	void topology_hotunplug_apic(unsigned int cpu)
	{
	u32 apic_id = cpuid_to_apicid[cpu];

	if (apic_id == BAD_APICID)
	return;

	per_cpu(x86_cpu_to_apicid, cpu) = BAD_APICID;
	clear_bit(apic_id, phys_cpu_present_map);
	set_cpu_present(cpu, false);
	}
	#endif

	#ifdef CONFIG_X86_LOCAL_APIC
	static unsigned int max_possible_cpus __initdata = NR_CPUS;

	/**
	* topology_apply_cmdline_limits_early - Apply topology command line limits early
	*
	* Ensure that command line limits are in effect before firmware parsing
	* takes place.
	*/
	void __init topology_apply_cmdline_limits_early(void)
	{
	unsigned int possible = nr_cpu_ids;

	/* 'maxcpus=0' 'nosmp' 'nolapic' 'disableapic' 'noapic' */
	if (!setup_max_cpus \|\| ioapic_is_disabled \|\| apic_is_disabled)
	possible = 1;

	/* 'possible_cpus=N' */
	possible = min_t(unsigned int, max_possible_cpus, possible);

	if (possible < nr_cpu_ids) {
	pr_info("Limiting to %u possible CPUs\n", possible);
	set_nr_cpu_ids(possible);
	}
	}

	static __init bool restrict_to_up(void)
	{
	if (!smp_found_config \|\| ioapic_is_disabled)
	return true;
	/*
	* XEN PV is special as it does not advertise the local APIC
	* properly, but provides a fake topology for it so that the
	* infrastructure works. So don't apply the restrictions vs. APIC
	* here.
	*/
	if (xen_pv_domain())
	return false;

	return apic_is_disabled;
	}

	void __init topology_init_possible_cpus(void)
	{
	unsigned int assigned = topo_info.nr_assigned_cpus;
	unsigned int disabled = topo_info.nr_disabled_cpus;
	unsigned int cnta, cntb, cpu, allowed = 1;
	unsigned int total = assigned + disabled;
	u32 apicid, firstid;

	/*
	* If there was no APIC registered, then fake one so that the
	* topology bitmap is populated. That ensures that the code below
	* is valid and the various query interfaces can be used
	* unconditionally. This does not affect the actual APIC code in
	* any way because either the local APIC address has not been
	* registered or the local APIC was disabled on the command line.
	*/
	if (topo_info.boot_cpu_apic_id == BAD_APICID)
	topology_register_boot_apic(0);

	if (!restrict_to_up()) {
	if (WARN_ON_ONCE(assigned > nr_cpu_ids)) {
	disabled += assigned - nr_cpu_ids;
	assigned = nr_cpu_ids;
	}
	allowed = min_t(unsigned int, total, nr_cpu_ids);
	}

	if (total > allowed)
	pr_warn("%u possible CPUs exceed the limit of %u\n", total, allowed);

	assigned = min_t(unsigned int, allowed, assigned);
	disabled = allowed - assigned;

	topo_info.nr_assigned_cpus = assigned;
	topo_info.nr_disabled_cpus = disabled;

	total_cpus = allowed;
	set_nr_cpu_ids(allowed);

	cnta = domain_weight(TOPO_PKG_DOMAIN);
	cntb = domain_weight(TOPO_DIE_DOMAIN);
	__max_logical_packages = cnta;
	__max_dies_per_package = 1U << (get_count_order(cntb) - get_count_order(cnta));

	pr_info("Max. logical packages: %3u\n", cnta);
	pr_info("Max. logical dies: %3u\n", cntb);
	pr_info("Max. dies per package: %3u\n", __max_dies_per_package);

	cnta = domain_weight(TOPO_CORE_DOMAIN);
	cntb = domain_weight(TOPO_SMT_DOMAIN);
	/*
	* Can't use order delta here as order(cnta) can be equal
	* order(cntb) even if cnta != cntb.
	*/
	__max_threads_per_core = DIV_ROUND_UP(cntb, cnta);
	pr_info("Max. threads per core: %3u\n", __max_threads_per_core);

	firstid = find_first_bit(apic_maps[TOPO_SMT_DOMAIN].map, MAX_LOCAL_APIC);
	__num_cores_per_package = topology_unit_count(firstid, TOPO_CORE_DOMAIN, TOPO_PKG_DOMAIN);
	pr_info("Num. cores per package: %3u\n", __num_cores_per_package);
	__num_threads_per_package = topology_unit_count(firstid, TOPO_SMT_DOMAIN, TOPO_PKG_DOMAIN);
	pr_info("Num. threads per package: %3u\n", __num_threads_per_package);

	pr_info("Allowing %u present CPUs plus %u hotplug CPUs\n", assigned, disabled);
	if (topo_info.nr_rejected_cpus)
	pr_info("Rejected CPUs %u\n", topo_info.nr_rejected_cpus);

	init_cpu_present(cpumask_of(0));
	init_cpu_possible(cpumask_of(0));

	/* Assign CPU numbers to non-present CPUs */
	for (apicid = 0; disabled; disabled--, apicid++) {
	apicid = find_next_andnot_bit(apic_maps[TOPO_SMT_DOMAIN].map, phys_cpu_present_map,
	MAX_LOCAL_APIC, apicid);
	if (apicid >= MAX_LOCAL_APIC)
	break;
	cpuid_to_apicid[topo_info.nr_assigned_cpus++] = apicid;
	}

	for (cpu = 0; cpu < allowed; cpu++) {
	apicid = cpuid_to_apicid[cpu];

	set_cpu_possible(cpu, true);

	if (apicid == BAD_APICID)
	continue;

	cpu_mark_primary_thread(cpu, apicid);
	set_cpu_present(cpu, test_bit(apicid, phys_cpu_present_map));
	}
	}

	/*
	* Late SMP disable after sizing CPU masks when APIC/IOAPIC setup failed.
	*/
	void __init topology_reset_possible_cpus_up(void)
	{
	init_cpu_present(cpumask_of(0));
	init_cpu_possible(cpumask_of(0));

	bitmap_zero(phys_cpu_present_map, MAX_LOCAL_APIC);
	if (topo_info.boot_cpu_apic_id != BAD_APICID)
	set_bit(topo_info.boot_cpu_apic_id, phys_cpu_present_map);
	}

	static int __init setup_possible_cpus(char *str)
	{
	get_option(&str, &max_possible_cpus);
	return 0;
	}
	early_param("possible_cpus", setup_possible_cpus);
	#endif