From 4ca88b3f86cd03deecd48ca9880a7c2e7c6fb788 Mon Sep 17 00:00:00 2001
From: Sean Christopherson <sean.j.christopherson@intel.com>
Date: Tue, 16 Apr 2019 13:32:47 -0700
Subject: [PATCH] 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>
---
arch/x86/kvm/lapic.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 0fd58571c453b..4e000712cb828 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -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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