KVM: selftests: Create GUEST_MEMFD for relevant invalid flags testcases

Actually create a GUEST_MEMFD instance and pass it to KVM when doing
negative tests for KVM_SET_USER_MEMORY_REGION2 + KVM_MEM_GUEST_MEMFD.
Without a valid GUEST_MEMFD file descriptor, KVM_SET_USER_MEMORY_REGION2
will always fail with -EINVAL, resulting in false passes for any and all
tests of illegal combinations of KVM_MEM_GUEST_MEMFD and other flags.

Fixes: 5d74316466f4 ("KVM: selftests: Add a memory region subtest to validate invalid flags")
Link: https://lore.kernel.org/r/20240222190612.2942589-5-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

diff --git a/tools/testing/selftests/kvm/set_memory_region_test.c b/tools/testing/selftests/kvm/set_memory_region_test.c
index 40337f5..9df4b61 100644 (file)
--- a/tools/testing/selftests/kvm/set_memory_region_test.c
+++ b/tools/testing/selftests/kvm/set_memory_region_test.c
@@ -367,11 +367,15 @@ static void test_invalid_memory_region_flags(void)
        }
 
        if (supported_flags & KVM_MEM_GUEST_MEMFD) {
+               int guest_memfd = vm_create_guest_memfd(vm, MEM_REGION_SIZE, 0);
+
                r = __vm_set_user_memory_region2(vm, 0,
                                                 KVM_MEM_LOG_DIRTY_PAGES | KVM_MEM_GUEST_MEMFD,
-                                                0, MEM_REGION_SIZE, NULL, 0, 0);
+                                                0, MEM_REGION_SIZE, NULL, guest_memfd, 0);
                TEST_ASSERT(r && errno == EINVAL,
                            "KVM_SET_USER_MEMORY_REGION2 should have failed, dirty logging private memory is unsupported");
+
+               close(guest_memfd);
        }
 }