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: Sean Christopherson <seanjc@google.com>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Message-Id: <1623050385-100988-1-git-send-email-wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 8120e86..6d72d8f 100644 (file)
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -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;