linux-kernel - [PATCH] x86/apic: mask IOAPIC entries when disable LAPIC

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Date:   Wed, 15 Jan 2020 16:22:19 +0800
From:   Tony W Wang-oc <TonyWWang-oc@...oxin.com>
To:     <tglx@...utronix.de>, <mingo@...hat.com>, <bp@...en8.de>,
        <hpa@...or.com>, <x86@...nel.org>, <peterz@...radead.org>,
        <tony.luck@...el.com>, <jacob.jun.pan@...ux.intel.com>,
        <wangkefeng.wang@...wei.com>, <jbeulich@...e.com>,
        <sean.j.christopherson@...el.com>, <linux-kernel@...r.kernel.org>
CC:     <DavidWang@...oxin.com>, <CooperYan@...oxin.com>,
        <QiyuanWang@...oxin.com>, <HerryYang@...oxin.com>
Subject: [PATCH] x86/apic: mask IOAPIC entries when disable LAPIC

When system suspend to S1, LAPIC disabled via soft but some IOAPIC
entries are unmask like IOAPIC 0 pin 9 which is for acpi interrupt.
This state IOAPIC can response external interrupt, but the interrupt
message can not handled by LAPIC.

When wakeup system via keyboard/rtc, level triggered interrupt IOAPIC 0
pin 9 RTE's Remote IRR bit may be set to 1 but LAPIC does not send EOI
for it. So this Remote IRR bit will remain all the time. This cause the
following S1 suspend sequence failed because software lockup in
__synchronize_hardirq.

Mask IOAPIC entries when disable LAPIC to make IOAPIC completely quiet
when LAPIC disabled.

Signed-off-by: Tony W Wang-oc <TonyWWang-oc@...oxin.com>
---
 arch/x86/kernel/apic/apic.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index 28446fa..233239a 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -2626,6 +2626,12 @@ static int lapic_suspend(void)
 #endif

 	local_irq_save(flags);
+
+	/*
+	 * Make IOAPIC quiet before disable LAPIC
+	 */
+	mask_ioapic_entries();
+
 	disable_local_APIC();

 	irq_remapping_disable();
-- 
2.7.4