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authorJens Freimann2015-04-17 10:21:04 +0200
committerChristian Borntraeger2015-05-08 15:51:15 +0200
commitffeca0ae880055457e56e45fd79cfa28d7160c30 (patch)
treecf4f49a36cc28c34a0d829015e00bf309e2f1af7 /arch/s390/kvm
parent27406cd50cf6653196eea8ebbb15a75596da01ca (diff)
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 <jfrei@linux.vnet.ibm.com> Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com> Reviewed-by: Dominik Dingel <dingel@linux.vnet.ibm.com> Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Diffstat (limited to 'arch/s390/kvm')
-rw-r--r--arch/s390/kvm/interrupt.c11
1 files changed, 4 insertions, 7 deletions
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);