Commit e898da78 authored by Wanpeng Li's avatar Wanpeng Li Committed by Paolo Bonzini
Browse files

KVM: LAPIC: Write 0 to TMICT should also cancel vmx-preemption timer 



According to the SDM 10.5.4.1:

  A write of 0 to the initial-count register effectively stops the local
  APIC timer, in both one-shot and periodic mode.

However, the lapic timer oneshot/periodic mode which is emulated by vmx-preemption
timer doesn't stop by writing 0 to TMICT since vmx->hv_deadline_tsc is still
programmed and the guest will receive the spurious timer interrupt later. This
patch fixes it by also cancelling the vmx-preemption timer when writing 0 to
the initial-count register.

Reviewed-by: default avatarSean Christopherson <seanjc@google.com>
Signed-off-by: default avatarWanpeng Li <wanpengli@tencent.com>
Message-Id: <1623050385-100988-1-git-send-email-wanpengli@tencent.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 4f13d471

arch/x86/kvm/lapic.c

+11 −6
Original line number Diff line number Diff line
@@ -1494,6 +1494,15 @@ static void limit_periodic_timer_frequency(struct kvm_lapic *apic) 


static void cancel_hv_timer(struct kvm_lapic *apic);



static void cancel_apic_timer(struct kvm_lapic *apic)

{

	hrtimer_cancel(&apic->lapic_timer.timer);

	preempt_disable();

	if (apic->lapic_timer.hv_timer_in_use)

		cancel_hv_timer(apic);

	preempt_enable();

}



static void apic_update_lvtt(struct kvm_lapic *apic)

{

	u32 timer_mode = kvm_lapic_get_reg(apic, APIC_LVTT) &
@@ -1502,11 +1511,7 @@ static void apic_update_lvtt(struct kvm_lapic *apic) 
	if (apic->lapic_timer.timer_mode != timer_mode) {

		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();

			cancel_apic_timer(apic);

			kvm_lapic_set_reg(apic, APIC_TMICT, 0);

			apic->lapic_timer.period = 0;

			apic->lapic_timer.tscdeadline = 0;
@@ -2092,7 +2097,7 @@ int kvm_lapic_reg_write(struct kvm_lapic *apic, u32 reg, u32 val) 
		if (apic_lvtt_tscdeadline(apic))

			break;



		hrtimer_cancel(&apic->lapic_timer.timer);

		cancel_apic_timer(apic);

		kvm_lapic_set_reg(apic, APIC_TMICT, val);

		start_apic_timer(apic);

		break;