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Commit 0114a8e8 authored by Dou Liyang's avatar Dou Liyang Committed by Thomas Gleixner
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x86/apic: Construct a selector for the interrupt delivery mode 



There are quite some switches which are used to determine the final
interrupt delivery mode, as shown below:

1) Kconfig: CONFIG_X86_64; CONFIG_X86_LOCAL_APIC; CONFIG_x86_IO_APIC
2) Command line options: disable_apic; skip_ioapic_setup
3) CPU Capability: boot_cpu_has(X86_FEATURE_APIC)
4) MP table: smp_found_config
5) ACPI: acpi_lapic; acpi_ioapic; nr_ioapic

These switches are disordered and scattered and there are also some
dependencies between them. These make the code difficult to maintain and
read.

Construct a selector to unify them into a single function, then, Use this
selector to get an interrupt delivery mode directly.

Signed-off-by: default avatarDou Liyang <douly.fnst@cn.fujitsu.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: yinghai@kernel.org
Cc: bhe@redhat.com
Link: https://lkml.kernel.org/r/1505293975-26005-2-git-send-email-douly.fnst@cn.fujitsu.com
parent e19b205b

arch/x86/kernel/apic/apic.c

+52 −0
Original line number Diff line number Diff line
@@ -1218,6 +1218,58 @@ void __init sync_Arb_IDs(void) 
			APIC_INT_LEVELTRIG | APIC_DM_INIT);

}



enum apic_intr_mode {

	APIC_PIC,

	APIC_VIRTUAL_WIRE,

	APIC_SYMMETRIC_IO,

};



static int __init apic_intr_mode_select(void)

{

	/* Check kernel option */

	if (disable_apic) {

		pr_info("APIC disabled via kernel command line\n");

		return APIC_PIC;

	}



	/* Check BIOS */

#ifdef CONFIG_X86_64

	/* On 64-bit, the APIC must be integrated, Check local APIC only */

	if (!boot_cpu_has(X86_FEATURE_APIC)) {

		disable_apic = 1;

		pr_info("APIC disabled by BIOS\n");

		return APIC_PIC;

	}

#else

	/* On 32-bit, the APIC may be integrated APIC or 82489DX */



	/* Neither 82489DX nor integrated APIC ? */

	if (!boot_cpu_has(X86_FEATURE_APIC) && !smp_found_config) {

		disable_apic = 1;

		return APIC_PIC;

	}



	/* If the BIOS pretends there is an integrated APIC ? */

	if (!boot_cpu_has(X86_FEATURE_APIC) &&

		APIC_INTEGRATED(boot_cpu_apic_version)) {

		disable_apic = 1;

		pr_err(FW_BUG "Local APIC %d not detected, force emulation\n",

				       boot_cpu_physical_apicid);

		return APIC_PIC;

	}

#endif



	/* Check MP table or ACPI MADT configuration */

	if (!smp_found_config) {

		disable_ioapic_support();

		if (!acpi_lapic)

			pr_info("APIC: ACPI MADT or MP tables are not detected\n");

		return APIC_VIRTUAL_WIRE;

	}



	return APIC_SYMMETRIC_IO;

}



/*

 * An initial setup of the virtual wire mode.

 */