[PATCH RFC 11/17] KVM: selftests: Test guest_memfd with anonymous fsmount() tmpfs pool

[Ackerley Tng via B4 Relay]

From: Ackerley Tng <ackerleytng@xxxxxxxxxx>

Add test coverage verifying that creating a guest_memfd backed by an
anonymous tmpfs mount descriptor returned by fsmount() succeeds and
reports the requested file size.

Signed-off-by: Ackerley Tng <ackerleytng@xxxxxxxxxx>
---
 tools/testing/selftests/kvm/guest_memfd_test.c | 35 ++++++++++++++++++++------
 1 file changed, 27 insertions(+), 8 deletions(-)

diff --git a/tools/testing/selftests/kvm/guest_memfd_test.c b/tools/testing/selftests/kvm/guest_memfd_test.c
index e8199ed17b0f8..73212d5307049 100644
--- a/tools/testing/selftests/kvm/guest_memfd_test.c
+++ b/tools/testing/selftests/kvm/guest_memfd_test.c
@@ -541,12 +541,23 @@ static void test_resource_fd_tmpfs_huge(struct kvm_vm *vm)
 	close(pool_fd);
 }
 
-#define ____gmem_test(__test, __vm, __flags, __gmem_size, args...)	\
-do {									\
-	int fd = vm_create_guest_memfd(__vm, __gmem_size, __flags);	\
-									\
-	test_##__test(args);						\
-	close(fd);							\
+#define ____gmem_test(__test, __vm, __flags, __gmem_size, args...)		\
+do {										\
+	int pool_fd = -1;							\
+	int fd;									\
+										\
+	if ((__flags) & GUEST_MEMFD_FLAG_USE_RESOURCE) {			\
+		pool_fd = create_tmpfs_pool_fd("never", true, __gmem_size);	\
+		fd = vm_create_guest_memfd_resource(__vm, __gmem_size,		\
+						    __flags, pool_fd);		\
+	} else {								\
+		fd = vm_create_guest_memfd(__vm, __gmem_size, __flags);	\
+	}									\
+										\
+	test_##__test(args);							\
+	close(fd);								\
+	if (pool_fd >= 0)							\
+		close(pool_fd);							\
 } while (0)
 
 #define __gmem_test(__test, __vm, __flags, __gmem_size)			\
@@ -606,15 +617,23 @@ static void test_guest_memfd(unsigned long vm_type)
 	test_resource_fd_tmpfs_huge(vm);
 
 	__test_guest_memfd(vm, 0);
+	__test_guest_memfd(vm, GUEST_MEMFD_FLAG_USE_RESOURCE);
 
 	flags = vm_check_cap(vm, KVM_CAP_GUEST_MEMFD_FLAGS);
-	if (flags & GUEST_MEMFD_FLAG_MMAP)
+	if (flags & GUEST_MEMFD_FLAG_MMAP) {
 		__test_guest_memfd(vm, GUEST_MEMFD_FLAG_MMAP);
+		__test_guest_memfd(vm, GUEST_MEMFD_FLAG_MMAP |
+				       GUEST_MEMFD_FLAG_USE_RESOURCE);
+	}
 
 	/* MMAP should always be supported if INIT_SHARED is supported. */
-	if (flags & GUEST_MEMFD_FLAG_INIT_SHARED)
+	if (flags & GUEST_MEMFD_FLAG_INIT_SHARED) {
 		__test_guest_memfd(vm, GUEST_MEMFD_FLAG_MMAP |
 				       GUEST_MEMFD_FLAG_INIT_SHARED);
+		__test_guest_memfd(vm, GUEST_MEMFD_FLAG_MMAP |
+				       GUEST_MEMFD_FLAG_INIT_SHARED |
+				       GUEST_MEMFD_FLAG_USE_RESOURCE);
+	}
 
 	kvm_vm_free(vm);
 }

-- 
2.56.0.rc1.315.gc6ed9934b7-goog