[PATCH] KVM: selftests: Add tests - invalid inputs for KVM_CREATE_GUEST_MEMFD

[Ackerley Tng <ackerleytng@google.com>]

Test that invalid inputs for KVM_CREATE_GUEST_MEMFD, such as
non-page-aligned page size and invalid flags, are rejected by the
KVM_CREATE_GUEST_MEMFD with EINVAL

Signed-off-by: Ackerley Tng <ackerleytng@google.com>
---
 .../testing/selftests/kvm/guest_memfd_test.c  | 33 +++++++++++++++++++
 .../selftests/kvm/include/kvm_util_base.h     | 11 +++++--
 2 files changed, 42 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/kvm/guest_memfd_test.c b/tools/testing/selftests/kvm/guest_memfd_test.c
index eb93c608a7e0..a8e37f001297 100644
--- a/tools/testing/selftests/kvm/guest_memfd_test.c
+++ b/tools/testing/selftests/kvm/guest_memfd_test.c
@@ -90,6 +90,37 @@ static void test_fallocate(int fd, size_t page_size, size_t total_size)
 	TEST_ASSERT(!ret, "fallocate to restore punched hole should succeed");
 }
 
+static void test_create_guest_memfd_invalid(struct kvm_vm *vm, size_t page_size)
+{
+	int fd;
+	uint64_t size;
+	uint64_t flags;
+	uint64_t valid_flags = 0;
+
+	for (size = 1; size < page_size; size++) {
+		fd = __vm_create_guest_memfd(vm, size, 0);
+		TEST_ASSERT(
+			fd == -1,
+			"Creating guest memfds with non-page-aligned page sizes should fail");
+		TEST_ASSERT(errno == EINVAL, "... and errno should be set to EINVAL");
+	}
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+	valid_flags = KVM_GUEST_MEMFD_ALLOW_HUGEPAGE;
+#endif
+
+	for (flags = 1; flags; flags <<= 1) {
+		if (flags & valid_flags)
+			continue;
+
+		fd = __vm_create_guest_memfd(vm, page_size, flags);
+		TEST_ASSERT(
+			fd == -1,
+			"Creating guest memfds with invalid flags should fail");
+		TEST_ASSERT(errno == EINVAL, "... and errno should be set to EINVAL");
+	}
+}
+
 
 int main(int argc, char *argv[])
 {
@@ -103,6 +134,8 @@ int main(int argc, char *argv[])
 
 	vm = vm_create_barebones();
 
+	test_create_guest_memfd_invalid(vm, page_size);
+
 	fd = vm_create_guest_memfd(vm, total_size, 0);
 
 	test_file_read_write(fd);
diff --git a/tools/testing/selftests/kvm/include/kvm_util_base.h b/tools/testing/selftests/kvm/include/kvm_util_base.h
index 39b38c75b99c..8bdfadd72349 100644
--- a/tools/testing/selftests/kvm/include/kvm_util_base.h
+++ b/tools/testing/selftests/kvm/include/kvm_util_base.h
@@ -474,7 +474,8 @@ static inline uint64_t vm_get_stat(struct kvm_vm *vm, const char *stat_name)
 }
 
 void vm_create_irqchip(struct kvm_vm *vm);
-static inline int vm_create_guest_memfd(struct kvm_vm *vm, uint64_t size,
+
+static inline int __vm_create_guest_memfd(struct kvm_vm *vm, uint64_t size,
 					uint64_t flags)
 {
 	struct kvm_create_guest_memfd gmem = {
@@ -482,7 +483,13 @@ static inline int vm_create_guest_memfd(struct kvm_vm *vm, uint64_t size,
 		.flags = flags,
 	};
 
-	int fd = __vm_ioctl(vm, KVM_CREATE_GUEST_MEMFD, &gmem);
+	return __vm_ioctl(vm, KVM_CREATE_GUEST_MEMFD, &gmem);
+}
+
+static inline int vm_create_guest_memfd(struct kvm_vm *vm, uint64_t size,
+					uint64_t flags)
+{
+	int fd = __vm_create_guest_memfd(vm, size, flags);
 
 	TEST_ASSERT(fd >= 0, KVM_IOCTL_ERROR(KVM_CREATE_GUEST_MEMFD, fd));
 	return fd;
-- 
2.42.0.rc1.204.g551eb34607-goog