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Commit ccbfa1d3 authored by Wanpeng Li's avatar Wanpeng Li Committed by Paolo Bonzini
Browse files

KVM: LAPIC: Introduce limit_periodic_timer_frequency 



Extract the logic of limit lapic periodic timer frequency to a new function,
this function will be used by later patches.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: default avatarWanpeng Li <wanpeng.li@hotmail.com>
Signed-off-by: default avatarRadim Krčmář <rkrcmar@redhat.com>
parent c69518c8

arch/x86/kvm/lapic.c

+22 −17
Original line number Diff line number Diff line
@@ -1301,6 +1301,27 @@ static void update_divide_count(struct kvm_lapic *apic) 
				   apic->divide_count);

}



static void limit_periodic_timer_frequency(struct kvm_lapic *apic)

{

	/*

	 * Do not allow the guest to program periodic timers with small

	 * interval, since the hrtimers are not throttled by the host

	 * scheduler.

	 */

	if (apic_lvtt_period(apic)) {

		s64 min_period = min_timer_period_us * 1000LL;



		if (apic->lapic_timer.period < min_period) {

			pr_info_ratelimited(

			    "kvm: vcpu %i: requested %lld ns "

			    "lapic timer period limited to %lld ns\n",

			    apic->vcpu->vcpu_id,

			    apic->lapic_timer.period, min_period);

			apic->lapic_timer.period = min_period;

		}

	}

}



static void apic_update_lvtt(struct kvm_lapic *apic)

{

	u32 timer_mode = kvm_lapic_get_reg(apic, APIC_LVTT) &
@@ -1445,23 +1466,7 @@ static bool set_target_expiration(struct kvm_lapic *apic) 
	if (!apic->lapic_timer.period)

		return false;



	/*

	 * Do not allow the guest to program periodic timers with small

	 * interval, since the hrtimers are not throttled by the host

	 * scheduler.

	 */

	if (apic_lvtt_period(apic)) {

		s64 min_period = min_timer_period_us * 1000LL;



		if (apic->lapic_timer.period < min_period) {

			pr_info_ratelimited(

			    "kvm: vcpu %i: requested %lld ns "

			    "lapic timer period limited to %lld ns\n",

			    apic->vcpu->vcpu_id,

			    apic->lapic_timer.period, min_period);

			apic->lapic_timer.period = min_period;

		}

	}

	limit_periodic_timer_frequency(apic);



	apic_debug("%s: bus cycle is %" PRId64 "ns, now 0x%016"

		   PRIx64 ", "