KVM: s390: fast path for sca_ext_call_pending

If CPUSTAT_ECALL_PEND isn't set, we can't have an external call pending,
so we can directly avoid taking the lock.

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

1 files changed, 4 insertions, 2 deletions

diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
index 831c9ac728ec..62ec925aa196 100644
--- a/arch/s390/kvm/interrupt.c
+++ b/arch/s390/kvm/interrupt.c
@@ -39,6 +39,9 @@ static int sca_ext_call_pending(struct kvm_vcpu *vcpu, int *src_id)
 {
         int c, scn;
 
+        if (!(atomic_read(&vcpu->arch.sie_block->cpuflags) & CPUSTAT_ECALL_PEND))
+                return 0;
+
         read_lock(&vcpu->kvm->arch.sca_lock);
         if (vcpu->kvm->arch.use_esca) {
                 struct esca_block *sca = vcpu->kvm->arch.sca;
@@ -60,8 +63,7 @@ static int sca_ext_call_pending(struct kvm_vcpu *vcpu, int *src_id)
         if (src_id)
                 *src_id = scn;
 
-        return c && atomic_read(&vcpu->arch.sie_block->cpuflags) &
-                        CPUSTAT_ECALL_PEND;
+        return c;
 }
 
 static int sca_inject_ext_call(struct kvm_vcpu *vcpu, int src_id)