KVM: selftests: Carve out helper to create "default" VM without vCPUs

Carve out portion of vm_create_default so that selftests can modify
a "default" VM prior to creating vcpus.
Signed-off-by: David Dunn <daviddunn@google.com>
Message-Id: <20220223225743.2703915-3-daviddunn@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

tools/testing/selftests/kvm/include/kvm_util_base.h

@@ -336,6 +336,9 @@ struct kvm_vm *vm_create_with_vcpus(enum vm_guest_mode mode, uint32_t nr_vcpus,
 				    uint32_t num_percpu_pages, void *guest_code,
 				    uint32_t vcpuids[]);
 
+/* Create a default VM without any vcpus. */
+struct kvm_vm *vm_create_without_vcpus(enum vm_guest_mode mode, uint64_t pages);
+
 /*
  * Adds a vCPU with reasonable defaults (e.g. a stack)
  *

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

@@ -362,6 +362,20 @@ struct kvm_vm *vm_create(enum vm_guest_mode mode, uint64_t phy_pages, int perm)
 	return vm;
 }
 
+struct kvm_vm *vm_create_without_vcpus(enum vm_guest_mode mode, uint64_t pages)
+{
+	struct kvm_vm *vm;
+
+	vm = vm_create(mode, pages, O_RDWR);
+
+	kvm_vm_elf_load(vm, program_invocation_name);
+
+#ifdef __x86_64__
+	vm_create_irqchip(vm);
+#endif
+	return vm;
+}
+
 /*
  * VM Create with customized parameters
  *
@@ -412,13 +426,8 @@ struct kvm_vm *vm_create_with_vcpus(enum vm_guest_mode mode, uint32_t nr_vcpus,
 		    nr_vcpus, kvm_check_cap(KVM_CAP_MAX_VCPUS));
 
 	pages = vm_adjust_num_guest_pages(mode, pages);
-	vm = vm_create(mode, pages, O_RDWR);
 
-	kvm_vm_elf_load(vm, program_invocation_name);
-
-#ifdef __x86_64__
-	vm_create_irqchip(vm);
-#endif
+	vm = vm_create_without_vcpus(mode, pages);
 
 	for (i = 0; i < nr_vcpus; ++i) {
 		uint32_t vcpuid = vcpuids ? vcpuids[i] : i;