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Subject[PATCH v6 1/3] KVM: LAPIC: Introduce limit_periodic_timer_frequency
Date
From: Wanpeng Li <wanpeng.li@hotmail.com>

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: Wanpeng Li <wanpeng.li@hotmail.com>
---
arch/x86/kvm/lapic.c | 39 ++++++++++++++++++++++-----------------
1 file changed, 22 insertions(+), 17 deletions(-)

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 6723e2c..8841bb5 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -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 ", "
--
2.7.4
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