Commit 2690ec2a authored Jul 22, 2019 by Thomas Gleixner Committed by Greg Kroah-Hartman Oct 05, 2019

x86/apic: Soft disable APIC before initializing it



[ Upstream commit 2640da4cccf5cc613bf26f0998b9e340f4b5f69c ]

If the APIC was already enabled on entry of setup_local_APIC() then
disabling it soft via the SPIV register makes a lot of sense.

That masks all LVT entries and brings it into a well defined state.

Otherwise previously enabled LVTs which are not touched in the setup
function stay unmasked and might surprise the just booting kernel.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20190722105219.068290579@linutronix.de


Signed-off-by: Sasha Levin <sashal@kernel.org>

parent beaaa190

arch/x86/kernel/apic/apic.c

+8 −0

Original line number	Diff line number	Diff line
		@@ -1303,6 +1303,14 @@ void setup_local_APIC(void)
		return;
		}

		/*
		* If this comes from kexec/kcrash the APIC might be enabled in
		* SPIV. Soft disable it before doing further initialization.
		*/
		value = apic_read(APIC_SPIV);
		value &= ~APIC_SPIV_APIC_ENABLED;
		apic_write(APIC_SPIV, value);

		#ifdef CONFIG_X86_32
		/* Pound the ESR really hard over the head with a big hammer - mbligh */
		if (lapic_is_integrated() && apic->disable_esr) {