Commit-ID: 2640da4cccf5cc613bf26f0998b9e340f4b5f69c Gitweb: https://git.kernel.org/tip/2640da4cccf5cc613bf26f0998b9e340f4b5f69c Author: Thomas Gleixner <t...@linutronix.de> AuthorDate: Mon, 22 Jul 2019 20:47:08 +0200 Committer: Thomas Gleixner <t...@linutronix.de> CommitDate: Thu, 25 Jul 2019 16:11:56 +0200
x86/apic: Soft disable APIC before initializing it 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 <t...@linutronix.de> Acked-by: Peter Zijlstra (Intel) <pet...@infradead.org> Link: https://lkml.kernel.org/r/20190722105219.068290...@linutronix.de --- arch/x86/kernel/apic/apic.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c index fa0846d4e000..621992de49ee 100644 --- a/arch/x86/kernel/apic/apic.c +++ b/arch/x86/kernel/apic/apic.c @@ -1522,6 +1522,14 @@ static 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) {
