[PATCH RFC v2 44/50] KVM: selftests: Test flag dependency of PFN_MODE on USE_RESOURCE

[Ackerley Tng via B4 Relay]

From: Ackerley Tng <ackerleytng@xxxxxxxxxx>

Creating a guest_memfd with GUEST_MEMFD_FLAG_PFN_MODE requires
GUEST_MEMFD_FLAG_USE_RESOURCE.

Skip testing GUEST_MEMFD_FLAG_PFN_MODE as an isolated flag in
test_guest_memfd_flags() because creating a guest_memfd with PFN_MODE
alone without USE_RESOURCE is rejected by KVM with EINVAL.

In test_resource_fd_invalid(), verify that attempting to create a
guest_memfd with GUEST_MEMFD_FLAG_PFN_MODE without
GUEST_MEMFD_FLAG_USE_RESOURCE fails with EINVAL.

Signed-off-by: Ackerley Tng <ackerleytng@xxxxxxxxxx>
---
 tools/include/uapi/linux/kvm.h                 | 1 +
 tools/testing/selftests/kvm/guest_memfd_test.c | 8 +++++++-
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/tools/include/uapi/linux/kvm.h b/tools/include/uapi/linux/kvm.h
index 66c1f40b50c29..3ef7bc37a7070 100644
--- a/tools/include/uapi/linux/kvm.h
+++ b/tools/include/uapi/linux/kvm.h
@@ -1655,6 +1655,7 @@ struct kvm_memory_attributes {
 #define GUEST_MEMFD_FLAG_MMAP		(1ULL << 0)
 #define GUEST_MEMFD_FLAG_INIT_SHARED	(1ULL << 1)
 #define GUEST_MEMFD_FLAG_USE_RESOURCE	(1ULL << 2)
+#define GUEST_MEMFD_FLAG_PFN_MODE	(1ULL << 3)
 
 struct kvm_create_guest_memfd {
 	__u64 size;
diff --git a/tools/testing/selftests/kvm/guest_memfd_test.c b/tools/testing/selftests/kvm/guest_memfd_test.c
index cbc2f309664b2..fb9d50be2e3b6 100644
--- a/tools/testing/selftests/kvm/guest_memfd_test.c
+++ b/tools/testing/selftests/kvm/guest_memfd_test.c
@@ -407,7 +407,8 @@ 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)
+		if (flag == GUEST_MEMFD_FLAG_USE_RESOURCE ||
+		    flag == GUEST_MEMFD_FLAG_PFN_MODE)
 			continue;
 		fd = __vm_create_guest_memfd(vm, page_size, flag);
 		if (flag & valid_flags) {
@@ -432,6 +433,11 @@ static void test_resource_fd_invalid(struct kvm_vm *vm)
 	TEST_ASSERT(fd < 0, "guest_memfd with resource_fd but without flag should fail");
 	TEST_ASSERT_EQ(errno, EINVAL);
 
+	/* PFN_MODE without GUEST_MEMFD_FLAG_USE_RESOURCE fails */
+	fd = __vm_create_guest_memfd(vm, page_size, GUEST_MEMFD_FLAG_PFN_MODE);
+	TEST_ASSERT(fd < 0, "guest_memfd with PFN_MODE without USE_RESOURCE 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);

-- 
2.56.0.257.gf7497c7d27-goog