KVM: split kvm_arch_set_memory_region into prepare and commit

Required for SRCU convertion later.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 3fa0a10..c8002193 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -690,14 +690,12 @@
 }
 
 /* Section: memory related */
-int kvm_arch_set_memory_region(struct kvm *kvm,
-				struct kvm_userspace_memory_region *mem,
-				struct kvm_memory_slot old,
-				int user_alloc)
+int kvm_arch_prepare_memory_region(struct kvm *kvm,
+				   struct kvm_memory_slot *memslot,
+				   struct kvm_memory_slot old,
+				   struct kvm_userspace_memory_region *mem,
+				   int user_alloc)
 {
-	int i;
-	struct kvm_vcpu *vcpu;
-
 	/* A few sanity checks. We can have exactly one memory slot which has
 	   to start at guest virtual zero and which has to be located at a
 	   page boundary in userland and which has to end at a page boundary.
@@ -720,14 +718,23 @@
 	if (!user_alloc)
 		return -EINVAL;
 
+	return 0;
+}
+
+void kvm_arch_commit_memory_region(struct kvm *kvm,
+				struct kvm_userspace_memory_region *mem,
+				struct kvm_memory_slot old,
+				int user_alloc)
+{
+	int i;
+	struct kvm_vcpu *vcpu;
+
 	/* request update of sie control block for all available vcpus */
 	kvm_for_each_vcpu(i, vcpu, kvm) {
 		if (test_and_set_bit(KVM_REQ_MMU_RELOAD, &vcpu->requests))
 			continue;
 		kvm_s390_inject_sigp_stop(vcpu, ACTION_RELOADVCPU_ON_STOP);
 	}
-
-	return 0;
 }
 
 void kvm_arch_flush_shadow(struct kvm *kvm)