Commit 4ca88b3f authored Apr 16, 2019 by Sean Christopherson Committed by Paolo Bonzini Apr 30, 2019

KVM: lapic: Check for a pending timer intr prior to start_hv_timer()



Checking for a pending non-periodic interrupt in start_hv_timer() leads
to restart_apic_timer() making an unnecessary call to start_sw_timer()
due to start_hv_timer() returning false.

Alternatively, start_hv_timer() could return %true when there is a
pending non-periodic interrupt, but that approach is less intuitive,
i.e. would require a beefy comment to explain an otherwise simple check.

Cc: Liran Alon <liran.alon@oracle.com>
Cc: Wanpeng Li <wanpengli@tencent.com>
Suggested-by: Liran Alon <liran.alon@oracle.com>
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

parent f9927982

arch/x86/kvm/lapic.c

+5 −3

Original line number	Diff line number	Diff line
		@@ -1680,9 +1680,6 @@ static bool start_hv_timer(struct kvm_lapic *apic)
		if (!kvm_x86_ops->set_hv_timer)
		return false;

		if (!apic_lvtt_period(apic) && atomic_read(&ktimer->pending))
		return false;

		if (!ktimer->tscdeadline)
		return false;

		@@ -1735,8 +1732,13 @@ static void start_sw_timer(struct kvm_lapic *apic)
		static void restart_apic_timer(struct kvm_lapic *apic)
		{
		preempt_disable();

		if (!apic_lvtt_period(apic) && atomic_read(&apic->lapic_timer.pending))
		goto out;

		if (!start_hv_timer(apic))
		start_sw_timer(apic);
		out:
		preempt_enable();
		}

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