linux-kernel - [PATCH] KVM: LAPIC: Also cancel preemption timer when disarm LAPIC timer

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Message-Id: <1585031530-19823-1-git-send-email-wanpengli@tencent.com>
Date:   Tue, 24 Mar 2020 14:32:10 +0800
From:   Wanpeng Li <kernellwp@...il.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>
Subject: [PATCH] KVM: LAPIC: Also cancel preemption timer when disarm LAPIC timer

From: Wanpeng Li <wanpengli@...cent.com>

The timer is disarmed when switching between TSC deadline and other modes, 
we should set everything to disarmed state, however, LAPIC timer can be 
emulated by preemption timer, it still works if vmx->hv_deadline_timer is 
not -1. This patch also cancels preemption timer when disarm LAPIC timer.

Signed-off-by: Wanpeng Li <wanpengli@...cent.com>
---
 arch/x86/kvm/lapic.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 338de38..a38f1a8 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1445,6 +1445,8 @@ static void limit_periodic_timer_frequency(struct kvm_lapic *apic)
 	}
 }
 
+static void cancel_hv_timer(struct kvm_lapic *apic);
+
 static void apic_update_lvtt(struct kvm_lapic *apic)
 {
 	u32 timer_mode = kvm_lapic_get_reg(apic, APIC_LVTT) &
@@ -1454,6 +1456,10 @@ static void apic_update_lvtt(struct kvm_lapic *apic)
 		if (apic_lvtt_tscdeadline(apic) != (timer_mode ==
 				APIC_LVT_TIMER_TSCDEADLINE)) {
 			hrtimer_cancel(&apic->lapic_timer.timer);
+			preempt_disable();
+			if (apic->lapic_timer.hv_timer_in_use)
+				cancel_hv_timer(apic);
+			preempt_enable();
 			kvm_lapic_set_reg(apic, APIC_TMICT, 0);
 			apic->lapic_timer.period = 0;
 			apic->lapic_timer.tscdeadline = 0;
-- 
1.8.3.1