KVM: selftests: Add VM creation helper that "returns" vCPUs

Add a VM creator that "returns" the created vCPUs by filling the provided
array.  This will allow converting multi-vCPU tests away from hardcoded
vCPU IDs.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

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

@@ -563,10 +563,19 @@ struct kvm_vm *vm_create_default_with_vcpus(uint32_t nr_vcpus, uint64_t extra_me
 					    uint32_t vcpuids[]);
 
 /* Like vm_create_default_with_vcpus, but accepts mode and slot0 memory as a parameter */
-struct kvm_vm *vm_create_with_vcpus(enum vm_guest_mode mode, uint32_t nr_vcpus,
+struct kvm_vm *__vm_create_with_vcpus(enum vm_guest_mode mode, uint32_t nr_vcpus,
 				      uint64_t slot0_mem_pages, uint64_t extra_mem_pages,
 				      uint32_t num_percpu_pages, void *guest_code,
-				    uint32_t vcpuids[]);
+				      uint32_t vcpuids[], struct kvm_vcpu *vcpus[]);
+
+static inline struct kvm_vm *vm_create_with_vcpus(uint32_t nr_vcpus,
+						  void *guest_code,
+						  struct kvm_vcpu *vcpus[])
+{
+	return __vm_create_with_vcpus(VM_MODE_DEFAULT, nr_vcpus,
+				      DEFAULT_GUEST_PHY_PAGES, 0, 0,
+				      guest_code, NULL, vcpus);
+}
 
 /*
  * Create a VM with a single vCPU with reasonable defaults and @extra_mem_pages

tools/testing/selftests/kvm/kvm_page_table_test.c

@@ -268,8 +268,8 @@ static struct kvm_vm *pre_init_before_test(enum vm_guest_mode mode, void *arg)
 
 	/* Create a VM with enough guest pages */
 	guest_num_pages = test_mem_size / guest_page_size;
-	vm = vm_create_with_vcpus(mode, nr_vcpus, DEFAULT_GUEST_PHY_PAGES,
-				  guest_num_pages, 0, guest_code, NULL);
+	vm = __vm_create_with_vcpus(mode, nr_vcpus, DEFAULT_GUEST_PHY_PAGES,
+				    guest_num_pages, 0, guest_code, NULL, NULL);
 
 	/* Align down GPA of the testing memslot */
 	if (!p->phys_offset)

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

@@ -296,12 +296,13 @@ struct kvm_vm *__vm_create(enum vm_guest_mode mode, uint64_t nr_pages)
  * extra_mem_pages is only used to calculate the maximum page table size,
  * no real memory allocation for non-slot0 memory in this function.
  */
-struct kvm_vm *vm_create_with_vcpus(enum vm_guest_mode mode, uint32_t nr_vcpus,
+struct kvm_vm *__vm_create_with_vcpus(enum vm_guest_mode mode, uint32_t nr_vcpus,
 				      uint64_t slot0_mem_pages, uint64_t extra_mem_pages,
 				      uint32_t num_percpu_pages, void *guest_code,
-				    uint32_t vcpuids[])
+				      uint32_t vcpuids[], struct kvm_vcpu *vcpus[])
 {
 	uint64_t vcpu_pages, extra_pg_pages, pages;
+	struct kvm_vcpu *vcpu;
 	struct kvm_vm *vm;
 	int i;
 
@@ -328,7 +329,9 @@ struct kvm_vm *vm_create_with_vcpus(enum vm_guest_mode mode, uint32_t nr_vcpus,
 	for (i = 0; i < nr_vcpus; ++i) {
 		uint32_t vcpuid = vcpuids ? vcpuids[i] : i;
 
-		vm_vcpu_add(vm, vcpuid, guest_code);
+		vcpu = vm_vcpu_add(vm, vcpuid, guest_code);
+		if (vcpus)
+			vcpus[i] = vcpu;
 	}
 
 	return vm;
@@ -338,8 +341,8 @@ struct kvm_vm *vm_create_default_with_vcpus(uint32_t nr_vcpus, uint64_t extra_me
 					    uint32_t num_percpu_pages, void *guest_code,
 					    uint32_t vcpuids[])
 {
-	return vm_create_with_vcpus(VM_MODE_DEFAULT, nr_vcpus, DEFAULT_GUEST_PHY_PAGES,
-				    extra_mem_pages, num_percpu_pages, guest_code, vcpuids);
+	return __vm_create_with_vcpus(VM_MODE_DEFAULT, nr_vcpus, DEFAULT_GUEST_PHY_PAGES,
+				      extra_mem_pages, num_percpu_pages, guest_code, vcpuids, NULL);
 }
 
 struct kvm_vm *vm_create_default(uint32_t vcpuid, uint64_t extra_mem_pages,

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

@@ -147,8 +147,9 @@ struct kvm_vm *perf_test_create_vm(enum vm_guest_mode mode, int vcpus,
 	 * The memory is also added to memslot 0, but that's a benign side
 	 * effect as KVM allows aliasing HVAs in meslots.
 	 */
-	vm = vm_create_with_vcpus(mode, vcpus, slot0_pages, guest_num_pages, 0,
-				  perf_test_guest_code, NULL);
+	vm = __vm_create_with_vcpus(mode, vcpus, DEFAULT_GUEST_PHY_PAGES,
+				    slot0_pages + guest_num_pages, 0,
+				    perf_test_guest_code, NULL, NULL);
 
 	pta->vm = vm;