| From b52332d1a88e8a2a2e44ebd578276744e7601351 Mon Sep 17 00:00:00 2001 |
| From: Sasha Levin <sashal@kernel.org> |
| Date: Mon, 22 Jul 2019 20:47:08 +0200 |
| Subject: x86/apic: Soft disable APIC before initializing it |
| |
| From: Thomas Gleixner <tglx@linutronix.de> |
| |
| [ 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> |
| --- |
| 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 928ffdc21873c..232350519062b 100644 |
| --- a/arch/x86/kernel/apic/apic.c |
| +++ b/arch/x86/kernel/apic/apic.c |
| @@ -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) { |
| -- |
| 2.20.1 |
| |
