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Commit 07806c50 authored by Jiang Liu's avatar Jiang Liu Committed by Thomas Gleixner
Browse files

x86/apic: Refine enable_IR_x2apic() and related functions 



Refine enable_IR_x2apic() and related functions for better readability.

[ tglx: Removed the XAPIC mode change and split it out into a seperate
  	patch. Added comments. ]

Signed-off-by: default avatarJiang Liu <jiang.liu@linux.intel.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: iommu@lists.linux-foundation.org
Cc: H. Peter Anvin <hpa@linux.intel.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: David Rientjes <rientjes@google.com>
Cc: HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com>
Cc: Jan Beulich <JBeulich@suse.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Oren Twaig <oren@scalemp.com>
Link: http://lkml.kernel.org/r/1420615903-28253-8-git-send-email-jiang.liu@linux.intel.com


Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 89356cf2

arch/x86/kernel/apic/apic.c

+47 −45
Original line number Diff line number Diff line
@@ -1573,7 +1573,7 @@ void enable_x2apic(void) 
}

#endif /* CONFIG_X86_X2APIC */



int __init enable_IR(void)

static int __init try_to_enable_IR(void)

{

#ifdef CONFIG_IRQ_REMAP

	if (!irq_remapping_supported()) {
@@ -1586,17 +1586,51 @@ int __init enable_IR(void) 
			"io-apic setup\n");

		return -1;

	}



#endif

	return irq_remapping_enable();

}



static __init void try_to_enable_x2apic(int ir_stat)

{

#ifdef CONFIG_X86_X2APIC

	if (!x2apic_supported())

		return;



	if (ir_stat < 0) {

		/* IR is required if there is APIC ID > 255 even when running

		 * under KVM

		 */

		if (max_physical_apicid > 255 ||

		    !hypervisor_x2apic_available()) {

			pr_info("IRQ remapping doesn't support X2APIC mode, disable x2apic.\n");

			if (x2apic_preenabled)

				disable_x2apic();

			return;

		}



		/*

		 * without IR all CPUs can be addressed by IOAPIC/MSI

		 * only in physical mode

		 */

		x2apic_force_phys();



	} else if (ir_stat == IRQ_REMAP_XAPIC_MODE) {

		pr_info("x2apic not enabled, IRQ remapping is in xapic mode\n");

		return;

	}



	if (!x2apic_mode) {

		x2apic_mode = 1;

		enable_x2apic();

		pr_info("Enabled x2apic\n");

	}

#endif

	return -1;

}



void __init enable_IR_x2apic(void)

{

	unsigned long flags;

	int ret;

	int hardware_init_ret;

	int ret, ir_stat;



	if (!IS_ENABLED(CONFIG_X86_X2APIC)) {

		u64 msr;
@@ -1606,8 +1640,8 @@ void __init enable_IR_x2apic(void) 
			panic("BIOS has enabled x2apic but kernel doesn't support x2apic, please disable x2apic in BIOS.\n");

	}



	hardware_init_ret = irq_remapping_prepare();

	if (hardware_init_ret && !x2apic_supported())

	ir_stat = irq_remapping_prepare();

	if (ir_stat < 0 && !x2apic_supported())

		return;



	ret = save_ioapic_entries();
@@ -1622,45 +1656,13 @@ void __init enable_IR_x2apic(void) 


	if (x2apic_preenabled && nox2apic)

		disable_x2apic();

	/* If irq_remapping_prepare() succeded, try to enable it */

	if (ir_stat >= 0)

		ir_stat = try_to_enable_IR();

	/* ir_stat contains the remap mode or an error code */

	try_to_enable_x2apic(ir_stat);



	if (hardware_init_ret)

		ret = -1;

	else

		ret = enable_IR();



	if (!x2apic_supported())

		goto skip_x2apic;



	if (ret < 0) {

		/* IR is required if there is APIC ID > 255 even when running

		 * under KVM

		 */

		if (max_physical_apicid > 255 ||

		    !hypervisor_x2apic_available()) {

			if (x2apic_preenabled)

				disable_x2apic();

			goto skip_x2apic;

		}

		/*

		 * without IR all CPUs can be addressed by IOAPIC/MSI

		 * only in physical mode

		 */

		x2apic_force_phys();

	}



	if (ret == IRQ_REMAP_XAPIC_MODE) {

		pr_info("x2apic not enabled, IRQ remapping is in xapic mode\n");

		goto skip_x2apic;

	}



	if (x2apic_supported() && !x2apic_mode) {

		x2apic_mode = 1;

		enable_x2apic();

		pr_info("Enabled x2apic\n");

	}



skip_x2apic:

	if (ret < 0) /* IR enabling failed */

	if (ir_stat < 0)

		restore_ioapic_entries();

	legacy_pic->restore_mask();

	local_irq_restore(flags);