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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>
hifive-unleashed-5.2
Sean Christopherson 2019-04-16 13:32:47 -07:00 committed by Paolo Bonzini
parent f99279825e
commit 4ca88b3f86
1 changed files with 5 additions and 3 deletions
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8
arch/x86/kvm/lapic.c
View File

@ -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();
}