From: Jens Freimann Date: Fri, 17 Apr 2015 08:21:04 +0000 (+0200) Subject: KVM: s390: optimize interrupt handling round trip time X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=ffeca0ae880055457e56e45fd79cfa28d7160c30;p=deliverable%2Flinux.git KVM: s390: optimize interrupt handling round trip time We can avoid checking guest control registers and guest PSW as well as all the masking and calculations on the interrupt masks when no interrupts are pending. Also, the check for IRQ_PEND_COUNT can be removed, because we won't enter the while loop if no interrupts are pending and invalid interrupt types can't be injected. Signed-off-by: Jens Freimann Reviewed-by: Cornelia Huck Reviewed-by: Dominik Dingel Acked-by: Christian Borntraeger --- diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c index 2836b25f63d3..acf4a4e660c0 100644 --- a/arch/s390/kvm/interrupt.c +++ b/arch/s390/kvm/interrupt.c @@ -134,6 +134,8 @@ static unsigned long deliverable_irqs(struct kvm_vcpu *vcpu) active_mask = pending_local_irqs(vcpu); active_mask |= pending_floating_irqs(vcpu); + if (!active_mask) + return 0; if (psw_extint_disabled(vcpu)) active_mask &= ~IRQ_PEND_EXT_MASK; @@ -941,12 +943,9 @@ int __must_check kvm_s390_deliver_pending_interrupts(struct kvm_vcpu *vcpu) if (cpu_timer_irq_pending(vcpu)) set_bit(IRQ_PEND_EXT_CPU_TIMER, &li->pending_irqs); - do { - irqs = deliverable_irqs(vcpu); + while ((irqs = deliverable_irqs(vcpu)) && !rc) { /* bits are in the order of interrupt priority */ irq_type = find_first_bit(&irqs, IRQ_PEND_COUNT); - if (irq_type == IRQ_PEND_COUNT) - break; if (is_ioirq(irq_type)) { rc = __deliver_io(vcpu, irq_type); } else { @@ -958,9 +957,7 @@ int __must_check kvm_s390_deliver_pending_interrupts(struct kvm_vcpu *vcpu) } rc = func(vcpu); } - if (rc) - break; - } while (!rc); + } set_intercept_indicators(vcpu);