From: Christian Borntraeger <borntraeger@de.ibm.com>
Date: Thu, 16 Apr 2015 14:58:22 +0000 (+0200)
Subject: KVM: s390: optimize round trip time in request handling
X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=785dbef407d8;p=deliverable%2Flinux.git

KVM: s390: optimize round trip time in request handling

The fast path for a sie exit is that no kvm reqest is pending.
Make an early check to skip all single bit checks.

Reviewed-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
---

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 8cd8e7b288c5..f5282e62f87f 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -1720,6 +1720,8 @@ static bool ibs_enabled(struct kvm_vcpu *vcpu)
 
 static int kvm_s390_handle_requests(struct kvm_vcpu *vcpu)
 {
+	if (!vcpu->requests)
+		return 0;
 retry:
 	s390_vcpu_unblock(vcpu);
 	/*