[PATCH v2 07/13] KVM: selftests: Create a new guest_memfd for each testcase

Sean Christopherson
2025-10-03T23:26:25Z

Refactor the guest_memfd selftest to improve test isolation by creating a
a new guest_memfd for each testcase. Currently, the test reuses a single
guest_memfd instance for all testcases, and thus creates dependencies
between tests, e.g. not truncating folios from the guest_memfd instance
at the end of a test could lead to unexpected results (see the PUNCH_HOLE
purging that needs to done by in-flight the NUMA testcases[1]).

Invoke each test via a macro wrapper to create and close a guest_memfd
to cut down on the boilerplate copy+paste needed to create a test.

Link: https://lore.kernel.org/all/20250827175247.83322-10-shivankg@amd.com
Reported-by: Ackerley Tng <ackerleytng@google.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
Tested-by: Fuad Tabba <tabba@google.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
.../testing/selftests/kvm/guest_memfd_test.c | 31 ++++++++++---------
1 file changed, 16 insertions(+), 15 deletions(-)

diff --git a/tools/testing/selftests/kvm/guest_memfd_test.c b/tools/testing/selftests/kvm/guest_memfd_test.c
index a7c9601bd31e..afdc4d3a956d 100644
--- a/tools/testing/selftests/kvm/guest_memfd_test.c
+++ b/tools/testing/selftests/kvm/guest_memfd_test.c
@@ -26,7 +26,7 @@

static size_t page_size;

-static void test_file_read_write(int fd)
+static void test_file_read_write(int fd, size_t total_size)
{
char buf[64];

@@ -260,14 +260,18 @@ static void test_guest_memfd_flags(struct kvm_vm *vm)
}
}

+#define gmem_test(__test, __vm, __flags) \
+do { \
+ int fd = vm_create_guest_memfd(__vm, page_size * 4, __flags); \
+ \
+ test_##__test(fd, page_size * 4); \
+ close(fd); \
+} while (0)
+
static void test_guest_memfd(unsigned long vm_type)
{
struct kvm_vm *vm;
- size_t total_size;
uint64_t flags;
- int fd;
-
- total_size = page_size * 4;

vm = vm_create_barebones_type(vm_type);
flags = vm_check_cap(vm, KVM_CAP_GUEST_MEMFD_FLAGS);
@@ -279,24 +283,21 @@ static void test_guest_memfd(unsigned long vm_type)
test_create_guest_memfd_multiple(vm);
test_create_guest_memfd_invalid_sizes(vm, flags);

- fd = vm_create_guest_memfd(vm, total_size, flags);
-
- test_file_read_write(fd);
+ gmem_test(file_read_write, vm, flags);

if (flags & GUEST_MEMFD_FLAG_MMAP) {
- test_mmap_supported(fd, total_size);
- test_fault_overflow(fd, total_size);
+ gmem_test(mmap_supported, vm, flags);
+ gmem_test(fault_overflow, vm, flags);
} else {
- test_mmap_not_supported(fd, total_size);
+ gmem_test(mmap_not_supported, vm, flags);
}

- test_file_size(fd, total_size);
- test_fallocate(fd, total_size);
- test_invalid_punch_hole(fd, total_size);
+ gmem_test(file_size, vm, flags);
+ gmem_test(fallocate, vm, flags);
+ gmem_test(invalid_punch_hole, vm, flags);

test_guest_memfd_flags(vm);

- close(fd);
kvm_vm_free(vm);
}

--
2.51.0.618.g983fd99d29-goog