Commit 58aa34ab authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

x86/cpu/topology: Confine topology information 



Now that all external fiddling with num_processors and disabled_cpus is
gone, move the last user prefill_possible_map() into the topology code too
and remove the global visibility of these variables.

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/20240213210251.994756960@linutronix.de
parent e7530702

arch/x86/include/asm/smp.h

+0 −3
Original line number Diff line number Diff line
@@ -9,7 +9,6 @@ 
#include <asm/thread_info.h>



extern int smp_num_siblings;

extern unsigned int num_processors;



DECLARE_PER_CPU_READ_MOSTLY(cpumask_var_t, cpu_sibling_map);

DECLARE_PER_CPU_READ_MOSTLY(cpumask_var_t, cpu_core_map);
@@ -174,8 +173,6 @@ static inline struct cpumask *cpu_llc_shared_mask(int cpu) 
}

#endif /* CONFIG_SMP */



extern unsigned disabled_cpus;



#ifdef CONFIG_DEBUG_NMI_SELFTEST

extern void nmi_selftest(void);

#else

arch/x86/kernel/apic/apic.c

+0 −1
Original line number Diff line number Diff line
@@ -2054,7 +2054,6 @@ void __init init_apic_mappings(void) 
			pr_info("APIC: disable apic facility\n");

			apic_disable();

		}

		num_processors = 1;

	}

}

arch/x86/kernel/cpu/topology.c

+74 −2
Original line number Diff line number Diff line
@@ -29,8 +29,8 @@ u32 cpuid_to_apicid[] __read_mostly = { [0 ... NR_CPUS - 1] = BAD_APICID, }; 
 */

static u32 disabled_cpu_apicid __ro_after_init = BAD_APICID;



unsigned int num_processors;

unsigned disabled_cpus;

static unsigned int num_processors;

static unsigned int disabled_cpus;



/*

 * The number of allocated logical CPU IDs. Since logical CPU IDs are allocated
@@ -174,6 +174,71 @@ static int generic_processor_info(int apicid) 
	return cpu;

}



static int __initdata setup_possible_cpus = -1;



/*

 * cpu_possible_mask should be static, it cannot change as cpu's

 * are onlined, or offlined. The reason is per-cpu data-structures

 * are allocated by some modules at init time, and don't expect to

 * do this dynamically on cpu arrival/departure.

 * cpu_present_mask on the other hand can change dynamically.

 * In case when cpu_hotplug is not compiled, then we resort to current

 * behaviour, which is cpu_possible == cpu_present.

 * - Ashok Raj

 *

 * Three ways to find out the number of additional hotplug CPUs:

 * - If the BIOS specified disabled CPUs in ACPI/mptables use that.

 * - The user can overwrite it with possible_cpus=NUM

 * - Otherwise don't reserve additional CPUs.

 * We do this because additional CPUs waste a lot of memory.

 * -AK

 */

__init void prefill_possible_map(void)

{

	int i, possible;



	i = setup_max_cpus ?: 1;

	if (setup_possible_cpus == -1) {

		possible = num_processors;

#ifdef CONFIG_HOTPLUG_CPU

		if (setup_max_cpus)

			possible += disabled_cpus;

#else

		if (possible > i)

			possible = i;

#endif

	} else

		possible = setup_possible_cpus;



	total_cpus = max_t(int, possible, num_processors + disabled_cpus);



	/* nr_cpu_ids could be reduced via nr_cpus= */

	if (possible > nr_cpu_ids) {

		pr_warn("%d Processors exceeds NR_CPUS limit of %u\n",

			possible, nr_cpu_ids);

		possible = nr_cpu_ids;

	}



#ifdef CONFIG_HOTPLUG_CPU

	if (!setup_max_cpus)

#endif

	if (possible > i) {

		pr_warn("%d Processors exceeds max_cpus limit of %u\n",

			possible, setup_max_cpus);

		possible = i;

	}



	set_nr_cpu_ids(possible);



	pr_info("Allowing %d CPUs, %d hotplug CPUs\n",

		possible, max_t(int, possible - num_processors, 0));



	reset_cpu_possible_mask();



	for (i = 0; i < possible; i++)

		set_cpu_possible(i, true);

}



/**

 * topology_register_apic - Register an APIC in early topology maps

 * @apic_id:	The APIC ID to set up
@@ -251,6 +316,13 @@ void topology_hotunplug_apic(unsigned int cpu) 
}

#endif



static int __init _setup_possible_cpus(char *str)

{

	get_option(&str, &setup_possible_cpus);

	return 0;

}

early_param("possible_cpus", _setup_possible_cpus);



static int __init apic_set_disabled_cpu_apicid(char *arg)

{

	if (!arg || !get_option(&arg, &disabled_cpu_apicid))

arch/x86/kernel/smpboot.c

+0 −72
Original line number Diff line number Diff line
@@ -1291,78 +1291,6 @@ void __init native_smp_cpus_done(unsigned int max_cpus) 
	cache_aps_init();

}



static int __initdata setup_possible_cpus = -1;

static int __init _setup_possible_cpus(char *str)

{

	get_option(&str, &setup_possible_cpus);

	return 0;

}

early_param("possible_cpus", _setup_possible_cpus);





/*

 * cpu_possible_mask should be static, it cannot change as cpu's

 * are onlined, or offlined. The reason is per-cpu data-structures

 * are allocated by some modules at init time, and don't expect to

 * do this dynamically on cpu arrival/departure.

 * cpu_present_mask on the other hand can change dynamically.

 * In case when cpu_hotplug is not compiled, then we resort to current

 * behaviour, which is cpu_possible == cpu_present.

 * - Ashok Raj

 *

 * Three ways to find out the number of additional hotplug CPUs:

 * - If the BIOS specified disabled CPUs in ACPI/mptables use that.

 * - The user can overwrite it with possible_cpus=NUM

 * - Otherwise don't reserve additional CPUs.

 * We do this because additional CPUs waste a lot of memory.

 * -AK

 */

__init void prefill_possible_map(void)

{

	int i, possible;



	i = setup_max_cpus ?: 1;

	if (setup_possible_cpus == -1) {

		possible = num_processors;

#ifdef CONFIG_HOTPLUG_CPU

		if (setup_max_cpus)

			possible += disabled_cpus;

#else

		if (possible > i)

			possible = i;

#endif

	} else

		possible = setup_possible_cpus;



	total_cpus = max_t(int, possible, num_processors + disabled_cpus);



	/* nr_cpu_ids could be reduced via nr_cpus= */

	if (possible > nr_cpu_ids) {

		pr_warn("%d Processors exceeds NR_CPUS limit of %u\n",

			possible, nr_cpu_ids);

		possible = nr_cpu_ids;

	}



#ifdef CONFIG_HOTPLUG_CPU

	if (!setup_max_cpus)

#endif

	if (possible > i) {

		pr_warn("%d Processors exceeds max_cpus limit of %u\n",

			possible, setup_max_cpus);

		possible = i;

	}



	set_nr_cpu_ids(possible);



	pr_info("Allowing %d CPUs, %d hotplug CPUs\n",

		possible, max_t(int, possible - num_processors, 0));



	reset_cpu_possible_mask();



	for (i = 0; i < possible; i++)

		set_cpu_possible(i, true);

}



/* correctly size the local cpu masks */

void __init setup_cpu_local_masks(void)

{