linux-kernel - [PATCH] KVM: LAPIC: Level-sensitive interrupts are not support for LINT1

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Date:   Thu, 12 Oct 2017 21:27:53 -0700
From:   Wanpeng Li <kernellwp@...il.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Wanpeng Li <wanpeng.li@...mail.com>
Subject: [PATCH] KVM: LAPIC: Level-sensitive interrupts are not support for LINT1

From: Wanpeng Li <wanpeng.li@...mail.com>

SDM 10.5.1 mentioned:
 Software should always set the trigger mode in the LVT LINT1 register to 0 (edge
 sensitive). Level-sensitive interrupts are not supported from LINT1.

I can intercept both Linux/windows 7/windows 2016 guests on my hand will set 
Level-sensitive trigger mode to LVT LINT1 register during boot.  

This patch avoids the software too fool to set the level-sensitive trigger mode 
to LVT LINT1 register.

Cc: Paolo Bonzini <pbonzini@...hat.com>
Cc: Radim Krčmář <rkrcmar@...hat.com>
Signed-off-by: Wanpeng Li <wanpeng.li@...mail.com>
---
 arch/x86/kvm/lapic.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index a778f1a..26593c7 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1758,6 +1758,8 @@ int kvm_lapic_reg_write(struct kvm_lapic *apic, u32 reg, u32 val)
 			val |= APIC_LVT_MASKED;
 
 		val &= apic_lvt_mask[(reg - APIC_LVTT) >> 4];
+		if (reg == APIC_LVT1)
+			val &= ~APIC_LVT_LEVEL_TRIGGER;
 		kvm_lapic_set_reg(apic, reg, val);
 
 		break;
-- 
2.7.4