Commit e8122513 authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Dave Hansen
Browse files

x86/apic: Sanitize num_processors handling 



num_processors is 0 by default and only gets incremented when local APICs
are registered.

Make init_apic_mappings(), which tries to enable the local APIC in the case
that no SMP configuration was found set num_processors to 1.

This allows to remove yet another check for the local APIC and yet another
place which registers the boot CPUs local APIC ID.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarDave Hansen <dave.hansen@linux.intel.com>
Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: default avatarMichael Kelley <mikelley@microsoft.com>
Tested-by: default avatarSohil Mehta <sohil.mehta@intel.com>
Tested-by: Juergen Gross <jgross@suse.com> # Xen PV (dom0 and unpriv. guest)
parent 24889a3a

arch/x86/kernel/apic/apic.c

+6 −3
Original line number Diff line number Diff line
@@ -2130,10 +2130,13 @@ void __init init_apic_mappings(void) 
	if (x2apic_mode)

		return;



	if (!smp_found_config && !detect_init_APIC()) {

	if (!smp_found_config) {

		if (!detect_init_APIC()) {

			pr_info("APIC: disable apic facility\n");

			apic_disable();

		}

		num_processors = 1;

	}

}



static __init void apic_set_fixmap(void)

arch/x86/kernel/smpboot.c

+0 −18
Original line number Diff line number Diff line
@@ -1397,24 +1397,6 @@ __init void prefill_possible_map(void) 
{

	int i, possible;



	/* No processor was found in mptable or ACPI MADT */

	if (!num_processors) {

		if (boot_cpu_has(X86_FEATURE_APIC)) {

			int apicid = boot_cpu_physical_apicid;

			int cpu = read_apic_id();



			pr_warn("Boot CPU (id %d) not listed by BIOS\n", cpu);



			/* Make sure boot cpu is enumerated */

			if (apic->cpu_present_to_apicid(0) == BAD_APICID &&

			    apic->apic_id_valid(apicid))

				generic_processor_info(apicid);

		}



		if (!num_processors)

			num_processors = 1;

	}



	i = setup_max_cpus ?: 1;

	if (setup_possible_cpus == -1) {

		possible = num_processors;