KVM: selftests: Require vCPU output array when creating VM with vCPUs

Require the caller of __vm_create_with_vcpus() to provide a non-NULL
array of vCPUs now that all callers do so.  It's extremely unlikely a
test will have a legitimate use case for creating a VM with vCPUs without
wanting to do something with those vCPUs, and if there is such a use case,
requiring that one-off test to provide a dummy array is a minor
annoyance.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

tools/testing/selftests/kvm/lib/kvm_util.c

@@ -302,10 +302,11 @@ struct kvm_vm *__vm_create_with_vcpus(enum vm_guest_mode mode, uint32_t nr_vcpus
 				      struct kvm_vcpu *vcpus[])
 {
 	uint64_t vcpu_pages, extra_pg_pages, pages;
-	struct kvm_vcpu *vcpu;
 	struct kvm_vm *vm;
 	int i;
 
+	TEST_ASSERT(!nr_vcpus || vcpus, "Must provide vCPU array");
+
 	/* Force slot0 memory size not small than DEFAULT_GUEST_PHY_PAGES */
 	if (slot0_mem_pages < DEFAULT_GUEST_PHY_PAGES)
 		slot0_mem_pages = DEFAULT_GUEST_PHY_PAGES;
@@ -326,11 +327,8 @@ struct kvm_vm *__vm_create_with_vcpus(enum vm_guest_mode mode, uint32_t nr_vcpus
 
 	vm = __vm_create(mode, pages);
 
-	for (i = 0; i < nr_vcpus; ++i) {
-		vcpu = vm_vcpu_add(vm, i, guest_code);
-		if (vcpus)
-			vcpus[i] = vcpu;
-	}
+	for (i = 0; i < nr_vcpus; ++i)
+		vcpus[i] = vm_vcpu_add(vm, i, guest_code);
 
 	return vm;
 }