Commit df0d9923 authored Oct 03, 2025 by Ackerley Tng Committed by Sean Christopherson Oct 10, 2025

KVM: selftests: Add test coverage for guest_memfd without GUEST_MEMFD_FLAG_MMAP



If a VM type supports KVM_CAP_GUEST_MEMFD_MMAP, the guest_memfd test will
run all test cases with GUEST_MEMFD_FLAG_MMAP set.  This leaves the code
path for creating a non-mmap()-able guest_memfd on a VM that supports
mappable guest memfds untested.

Refactor the test to run the main test suite with a given set of flags.
Then, for VM types that support the mappable capability, invoke the test
suite twice: once with no flags, and once with GUEST_MEMFD_FLAG_MMAP
set.

This ensures both creation paths are properly exercised on capable VMs.

Run test_guest_memfd_flags() only once per VM type since it depends only
on the set of valid/supported flags, i.e. iterating over an arbitrary set
of flags is both unnecessary and wrong.

Signed-off-by: Ackerley Tng <ackerleytng@google.com>
[sean: use double-underscores for the inner helper]
Reviewed-by: Fuad Tabba <tabba@google.com>
Tested-by: Fuad Tabba <tabba@google.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Link: https://lore.kernel.org/r/20251003232606.4070510-9-seanjc@google.com


Signed-off-by: Sean Christopherson <seanjc@google.com>

parent 21d602ed

tools/testing/selftests/kvm/guest_memfd_test.c

+16 −11

Original line number	Diff line number	Diff line
		@@ -268,18 +268,8 @@ do { \
		close(fd); \
		} while (0)

		static void test_guest_memfd(unsigned long vm_type)
		static void __test_guest_memfd(struct kvm_vm *vm, uint64_t flags)
		{
		struct kvm_vm *vm;
		uint64_t flags;

		vm = vm_create_barebones_type(vm_type);
		flags = vm_check_cap(vm, KVM_CAP_GUEST_MEMFD_FLAGS);

		/* This test doesn't yet support testing mmap() on private memory. */
		if (!(flags & GUEST_MEMFD_FLAG_INIT_SHARED))
		flags &= ~GUEST_MEMFD_FLAG_MMAP;

		test_create_guest_memfd_multiple(vm);
		test_create_guest_memfd_invalid_sizes(vm, flags);

		@@ -295,9 +285,24 @@ static void test_guest_memfd(unsigned long vm_type)
		gmem_test(file_size, vm, flags);
		gmem_test(fallocate, vm, flags);
		gmem_test(invalid_punch_hole, vm, flags);
		}

		static void test_guest_memfd(unsigned long vm_type)
		{
		struct kvm_vm *vm = vm_create_barebones_type(vm_type);
		uint64_t flags;

		test_guest_memfd_flags(vm);

		__test_guest_memfd(vm, 0);

		flags = vm_check_cap(vm, KVM_CAP_GUEST_MEMFD_FLAGS);

		/* MMAP should always be supported if INIT_SHARED is supported. */
		if (flags & GUEST_MEMFD_FLAG_INIT_SHARED)
		__test_guest_memfd(vm, GUEST_MEMFD_FLAG_MMAP \|
		GUEST_MEMFD_FLAG_INIT_SHARED);

		kvm_vm_free(vm);
		}