Commit ea2dd8a5 authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

x86/cpu/topology: Assign hotpluggable CPUIDs during init 



There is no point in assigning the CPU numbers during ACPI physical
hotplug. The number of possible hotplug CPUs is known when the possible map
is initialized, so the CPU numbers can be associated to the registered
non-present APIC IDs right there.

This allows to put more code into the __init section and makes the related
data __ro_after_init.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Tested-by: default avatarMichael Kelley <mhklinux@outlook.com>
Tested-by: default avatarSohil Mehta <sohil.mehta@intel.com>
Link: https://lore.kernel.org/r/20240213210252.517339971@linutronix.de
parent 7cdcdab1

arch/x86/kernel/cpu/topology.c

+18 −11
Original line number Diff line number Diff line
@@ -45,7 +45,7 @@ EXPORT_EARLY_PER_CPU_SYMBOL(x86_cpu_to_acpiid); 
DECLARE_BITMAP(phys_cpu_present_map, MAX_LOCAL_APIC) __read_mostly;



/* Used for CPU number allocation and parallel CPU bringup */

u32 cpuid_to_apicid[] __read_mostly = { [0 ... NR_CPUS - 1] = BAD_APICID, };

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;
@@ -60,7 +60,7 @@ static struct { 
	unsigned int		nr_rejected_cpus;

	u32			boot_cpu_apic_id;

	u32			real_bsp_apic_id;

} topo_info __read_mostly = {

} topo_info __ro_after_init = {

	.nr_assigned_cpus	= 1,

	.boot_cpu_apic_id	= BAD_APICID,

	.real_bsp_apic_id	= BAD_APICID,
@@ -133,7 +133,7 @@ static int topo_lookup_cpuid(u32 apic_id) 
	return -ENODEV;

}



static int topo_get_cpunr(u32 apic_id)

static __init int topo_get_cpunr(u32 apic_id)

{

	int cpu = topo_lookup_cpuid(apic_id);
@@ -149,8 +149,6 @@ static void topo_set_cpuids(unsigned int cpu, u32 apic_id, u32 acpi_id) 
	early_per_cpu(x86_cpu_to_apicid, cpu) = apic_id;

	early_per_cpu(x86_cpu_to_acpiid, cpu) = acpi_id;

#endif

	cpuid_to_apicid[cpu] = apic_id;



	set_cpu_possible(cpu, true);

	set_cpu_present(cpu, true);
@@ -206,6 +204,8 @@ static __init void topo_register_apic(u32 apic_id, u32 acpi_id, bool present) 
			cpu = 0;

		else

			cpu = topo_get_cpunr(apic_id);



		cpuid_to_apicid[cpu] = apic_id;

		topo_set_cpuids(cpu, apic_id, acpi_id);

	} else {

		topo_info.nr_disabled_cpus++;
@@ -277,12 +277,9 @@ int topology_hotplug_apic(u32 apic_id, u32 acpi_id) 
		return -ENODEV;



	cpu = topo_lookup_cpuid(apic_id);

	if (cpu < 0) {

		if (topo_info.nr_assigned_cpus >= nr_cpu_ids)

	if (cpu < 0)

		return -ENOSPC;



		cpu = topo_assign_cpunr(apic_id);

	}

	set_bit(apic_id, phys_cpu_present_map);

	topo_set_cpuids(cpu, apic_id, acpi_id);

	return cpu;
@@ -353,6 +350,7 @@ void __init topology_init_possible_cpus(void) 
	unsigned int disabled = topo_info.nr_disabled_cpus;

	unsigned int total = assigned + disabled;

	unsigned int cpu, allowed = 1;

	u32 apicid;



	if (!restrict_to_up()) {

		if (WARN_ON_ONCE(assigned > nr_cpu_ids)) {
@@ -381,8 +379,17 @@ void __init topology_init_possible_cpus(void) 
	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++) {

		u32 apicid = cpuid_to_apicid[cpu];

		apicid = cpuid_to_apicid[cpu];



		set_cpu_possible(cpu, true);