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Commit 7c6d9f97 authored by Suresh Siddha's avatar Suresh Siddha Committed by H. Peter Anvin
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x86, x2apic: use virtual wire A mode in disable_IO_APIC() with interrupt-remapping 



Impact: make kexec work with x2apic

disable_IO_APIC() gets called during crashdump aswell, which configures the
IO-APIC/LAPIC so that legacy interrupts can be delivered for the kexec'd kernel.

In the presence of interrupt-remapping, we need to change the
interrupt-remapping configuration aswell as modifying IO-APIC for virtual wire
B mode.

To keep things simple during the crash, use virtual wire A mode
(for which we don't need to touch io-apic and interrupt-remapping tables).

Signed-off-by: default avatarSuresh Siddha <suresh.b.siddha@intel.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: default avatarH. Peter Anvin <hpa@linux.intel.com>
parent 2e93456f

arch/x86/kernel/apic/io_apic.c

+10 −2
Original line number Diff line number Diff line
@@ -2040,8 +2040,13 @@ void disable_IO_APIC(void) 
	 * If the i8259 is routed through an IOAPIC

	 * Put that IOAPIC in virtual wire mode

	 * so legacy interrupts can be delivered.

	 *

	 * With interrupt-remapping, for now we will use virtual wire A mode,

	 * as virtual wire B is little complex (need to configure both

	 * IOAPIC RTE aswell as interrupt-remapping table entry).

	 * As this gets called during crash dump, keep this simple for now.

	 */

	if (ioapic_i8259.pin != -1) {

	if (ioapic_i8259.pin != -1 && !intr_remapping_enabled) {

		struct IO_APIC_route_entry entry;



		memset(&entry, 0, sizeof(entry));
@@ -2061,7 +2066,10 @@ void disable_IO_APIC(void) 
		ioapic_write_entry(ioapic_i8259.apic, ioapic_i8259.pin, entry);

	}



	disconnect_bsp_APIC(ioapic_i8259.pin != -1);

	/*

	 * Use virtual wire A mode when interrupt remapping is enabled.

	 */

	disconnect_bsp_APIC(!intr_remapping_enabled && ioapic_i8259.pin != -1);

}



#ifdef CONFIG_X86_32