Commit 0e53e7b6 authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

x86/cpu/topology: Sanitize the APIC admission logic 



Move the actually required content of generic_processor_id() into the call
sites and use common helper functions for them. This separates the early
boot registration and the ACPI hotplug mechanism completely which allows
further cleanups and improvements.

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/20240213210252.230433953@linutronix.de
parent 6055f6cf

arch/x86/kernel/cpu/topology.c

+77 −82
Original line number Diff line number Diff line
@@ -30,8 +30,10 @@ static struct { 
	unsigned int		nr_assigned_cpus;

	unsigned int		nr_disabled_cpus;

	unsigned int		nr_rejected_cpus;

	u32			boot_cpu_apic_id;

} topo_info __read_mostly = {

	.nr_assigned_cpus	= 1,

	.boot_cpu_apic_id	= BAD_APICID,

};



/*
@@ -83,78 +85,6 @@ early_initcall(smp_init_primary_thread_mask); 
static inline void cpu_mark_primary_thread(unsigned int cpu, unsigned int apicid) { }

#endif



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;

}



/*

 * Should use this API to allocate logical CPU IDs to keep nr_logical_cpuids

 * and cpuid_to_apicid[] synchronized.

 */

static int allocate_logical_cpuid(u32 apic_id)

{

	int cpu = topo_lookup_cpuid(apic_id);



	if (cpu >= 0)

		return cpu;



	return topo_info.nr_assigned_cpus++;

}



static void cpu_update_apic(unsigned int cpu, u32 apic_id)

{

#if defined(CONFIG_SMP) || defined(CONFIG_X86_64)

	early_per_cpu(x86_cpu_to_apicid, cpu) = apic_id;

#endif

	cpuid_to_apicid[cpu] = apic_id;

	set_cpu_possible(cpu, true);

	set_bit(apic_id, phys_cpu_present_map);

	set_cpu_present(cpu, true);



	if (system_state != SYSTEM_BOOTING)

		cpu_mark_primary_thread(cpu, apic_id);

}



static int generic_processor_info(int apicid)

{

	int cpu;



	/* The boot CPU must be set before MADT/MPTABLE parsing happens */

	if (cpuid_to_apicid[0] == BAD_APICID)

		panic("Boot CPU APIC not registered yet\n");



	if (apicid == boot_cpu_physical_apicid)

		return 0;



	if (disabled_cpu_apicid == apicid) {

		int thiscpu = topo_info.nr_assigned_cpus + topo_info.nr_disabled_cpus;



		pr_warn("APIC: Disabling requested cpu. Processor %d/0x%x ignored.\n",

			thiscpu, apicid);



		topo_info.nr_rejected_cpus++;

		return -ENODEV;

	}



	if (topo_info.nr_assigned_cpus >= nr_cpu_ids) {

		pr_warn_once("APIC: CPU limit of %d reached. Ignoring further CPUs\n", nr_cpu_ids);

		topo_info.nr_rejected_cpus++;

		return -ENOSPC;

	}



	cpu = allocate_logical_cpuid(apicid);

	cpu_update_apic(cpu, apicid);

	return cpu;

}



static int __initdata setup_possible_cpus = -1;



/*
@@ -222,6 +152,43 @@ __init void prefill_possible_map(void) 
		set_cpu_possible(i, true);

}



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 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

	cpuid_to_apicid[cpu] = apic_id;



	set_cpu_possible(cpu, true);

	set_cpu_present(cpu, true);



	if (system_state != SYSTEM_BOOTING)

		cpu_mark_primary_thread(cpu, apic_id);

}



/**

 * topology_register_apic - Register an APIC in early topology maps

 * @apic_id:	The APIC ID to set up
@@ -234,17 +201,40 @@ 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 (!present) {

		topo_info.nr_disabled_cpus++;

	if (disabled_cpu_apicid == apic_id) {

		pr_info("Disabling CPU as requested via 'disable_cpu_apicid=0x%x'.\n", apic_id);

		topo_info.nr_rejected_cpus++;

		return;

	}



	cpu = generic_processor_info(apic_id);

	if (cpu >= 0)

		early_per_cpu(x86_cpu_to_acpiid, cpu) = acpi_id;

	/* 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;

	}



	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);

		topo_set_cpuids(cpu, apic_id, acpi_id);

	} else {

		topo_info.nr_disabled_cpus++;

	}

}



/**
@@ -255,8 +245,10 @@ void __init topology_register_apic(u32 apic_id, u32 acpi_id, bool present) 
 */

void __init topology_register_boot_apic(u32 apic_id)

{

	cpuid_to_apicid[0] = apic_id;

	cpu_update_apic(0, apic_id);

	WARN_ON_ONCE(topo_info.boot_cpu_apic_id != BAD_APICID);



	topo_info.boot_cpu_apic_id = apic_id;

	topology_register_apic(apic_id, CPU_ACPIID_INVALID, true);

}



#ifdef CONFIG_ACPI_HOTPLUG_CPU
@@ -274,10 +266,13 @@ int topology_hotplug_apic(u32 apic_id, u32 acpi_id) 


	cpu = topo_lookup_cpuid(apic_id);

	if (cpu < 0) {

		cpu = generic_processor_info(apic_id);

		if (cpu >= 0)

			per_cpu(x86_cpu_to_acpiid, cpu) = acpi_id;

		if (topo_info.nr_assigned_cpus >= nr_cpu_ids)

			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;

}