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>

1 files changed, 2 insertions, 0 deletions

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);
         /*