From 2623c96f1172ae249b67de1dfc4eacebc8673876 Mon Sep 17 00:00:00 2001 From: Eric Farman Date: Wed, 25 Feb 2026 16:20:13 +0100 Subject: [PATCH] KVM: s390: only deliver service interrupt with payload Routine __inject_service() may set both the SERVICE and SERVICE_EV pending bits, and in the case of a pure service event the corresponding trip through __deliver_service_ev() will clear the SERVICE_EV bit only. This necessitates an additional trip through __deliver_service() for the other pending interrupt bit, however it is possible that the external interrupt parameters are zero and there is nothing to be delivered to the guest. To avoid sending empty data to the guest, let's only write out the SCLP data when there is something for the guest to do, otherwise bail out. Signed-off-by: Eric Farman Acked-by: Christian Borntraeger Signed-off-by: Christian Borntraeger Signed-off-by: Janosch Frank --- arch/s390/kvm/interrupt.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c index 18932a65ca68..dd0413387a9e 100644 --- a/arch/s390/kvm/interrupt.c +++ b/arch/s390/kvm/interrupt.c @@ -956,6 +956,9 @@ static int __must_check __deliver_service(struct kvm_vcpu *vcpu) set_bit(IRQ_PEND_EXT_SERVICE, &fi->masked_irqs); spin_unlock(&fi->lock); + if (!ext.ext_params) + return 0; + VCPU_EVENT(vcpu, 4, "deliver: sclp parameter 0x%x", ext.ext_params); vcpu->stat.deliver_service_signal++;