s390x/kvm: make setting of in-kernel irq routes more efficient

When we add new adapter routes we call kvm_irqchip_add_route() for every
virtqueue and in the same step also do the KVM_SET_GSI_ROUTING ioctl.

This is unnecessary costly as the interface allows us to set multiple
routes in one go. Let's first add all routes to the table stored in the
global kvm_state and then do the ioctl to commit the routes to the
in-kernel irqchip.

This saves us several ioctls to the kernel where for each call a list
is reallocated and populated.

Signed-off-by: Jens Freimann <jfrei@linux.vnet.ibm.com>
Reviewed-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>

hw/intc/s390_flic_kvm.c

@@ -228,6 +228,8 @@ static int kvm_s390_add_adapter_routes(S390FLICState *fs,
         routes->gsi[i] = ret;
         routes->adapter.ind_offset++;
     }
+    kvm_irqchip_commit_routes(kvm_state);
+
     /* Restore passed-in structure to original state. */
     routes->adapter.ind_offset = ind_offset;
     return 0;

kvm-all.c

@@ -1293,7 +1293,6 @@ int kvm_irqchip_add_adapter_route(KVMState *s, AdapterInfo *adapter)
     kroute.u.adapter.adapter_id = adapter->adapter_id;
 
     kvm_add_routing_entry(s, &kroute);
-    kvm_irqchip_commit_routes(s);
 
     return virq;
 }