[PATCH RFC 06/17] KVM: selftests: Test negative validation of resource_fd argument

[Ackerley Tng via B4 Relay <devnull+ackerleytng.google.com@kernel.org>]

From: Ackerley Tng <ackerleytng@google.com>

Add negative test coverage verifying that creating a guest_memfd
instance with a non-zero resource_fd when GUEST_MEMFD_FLAG_USE_RESOURCE
is clear fails with -EINVAL, and creating with an invalid resource_fd
fails with -EBADF.

Signed-off-by: Ackerley Tng <ackerleytng@google.com>
---
 tools/testing/selftests/kvm/guest_memfd_test.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/tools/testing/selftests/kvm/guest_memfd_test.c b/tools/testing/selftests/kvm/guest_memfd_test.c
index 2233d871a38f4..84b958b9ef715 100644
--- a/tools/testing/selftests/kvm/guest_memfd_test.c
+++ b/tools/testing/selftests/kvm/guest_memfd_test.c
@@ -404,6 +404,8 @@ static void test_guest_memfd_flags(struct kvm_vm *vm)
 	int fd;
 
 	for (flag = BIT(0); flag; flag <<= 1) {
+		if (flag == GUEST_MEMFD_FLAG_USE_RESOURCE)
+			continue;
 		fd = __vm_create_guest_memfd(vm, page_size, flag);
 		if (flag & valid_flags) {
 			TEST_ASSERT(fd >= 0,
@@ -418,6 +420,22 @@ static void test_guest_memfd_flags(struct kvm_vm *vm)
 	}
 }
 
+static void test_resource_fd_invalid(struct kvm_vm *vm)
+{
+	int fd;
+
+	/* Non-zero resource_fd without GUEST_MEMFD_FLAG_USE_RESOURCE fails */
+	fd = __vm_create_guest_memfd_resource(vm, page_size, 0, 1);
+	TEST_ASSERT(fd < 0, "guest_memfd with resource_fd but without flag should fail");
+	TEST_ASSERT_EQ(errno, EINVAL);
+
+	/* Bad file descriptor with GUEST_MEMFD_FLAG_USE_RESOURCE fails */
+	fd = __vm_create_guest_memfd_resource(vm, page_size,
+					      GUEST_MEMFD_FLAG_USE_RESOURCE, -1);
+	TEST_ASSERT(fd < 0, "guest_memfd with -1 resource_fd should fail");
+	TEST_ASSERT_EQ(errno, EBADF);
+}
+
 #define ____gmem_test(__test, __vm, __flags, __gmem_size, args...)	\
 do {									\
 	int fd = vm_create_guest_memfd(__vm, __gmem_size, __flags);	\
@@ -476,6 +494,8 @@ static void test_guest_memfd(unsigned long vm_type)
 
 	test_guest_memfd_flags(vm);
 
+	test_resource_fd_invalid(vm);
+
 	__test_guest_memfd(vm, 0);
 
 	flags = vm_check_cap(vm, KVM_CAP_GUEST_MEMFD_FLAGS);

-- 
2.56.0.rc1.315.gc6ed9934b7-goog