Ira Weiny <ira.weiny@xxxxxxxxx> writes:
> Ackerley Tng wrote:
>> Test that GUEST_MEMFD_FLAG_INIT_PRIVATE is only valid when
>> GUEST_MEMFD_FLAG_SUPPORT_SHARED is set.
>>
>> Change-Id: I506e236a232047cfaee17bcaed02ee14c8d25bbb
>> Signed-off-by: Ackerley Tng <ackerleytng@xxxxxxxxxx>
>> ---
>> .../testing/selftests/kvm/guest_memfd_test.c | 36 ++++++++++++-------
>> 1 file changed, 24 insertions(+), 12 deletions(-)
>>
>> diff --git a/tools/testing/selftests/kvm/guest_memfd_test.c b/tools/testing/selftests/kvm/guest_memfd_test.c
>> index 60aaba5808a5..bf2876cbd711 100644
>> --- a/tools/testing/selftests/kvm/guest_memfd_test.c
>> +++ b/tools/testing/selftests/kvm/guest_memfd_test.c
>> @@ -401,13 +401,31 @@ static void test_with_type(unsigned long vm_type, uint64_t guest_memfd_flags,
>> kvm_vm_release(vm);
>> }
>>
>> +static void test_vm_with_gmem_flag(struct kvm_vm *vm, uint64_t flag,
>> + bool expect_valid)
>> +{
>> + size_t page_size = getpagesize();
>> + int fd;
>> +
>> + fd = __vm_create_guest_memfd(vm, page_size, flag);
>> +
>> + if (expect_valid) {
>> + TEST_ASSERT(fd > 0,
>> + "guest_memfd() with flag '0x%lx' should be valid",
>> + flag);
>> + close(fd);
>> + } else {
>> + TEST_ASSERT(fd == -1 && errno == EINVAL,
>> + "guest_memfd() with flag '0x%lx' should fail with EINVAL",
>> + flag);
>> + }
>> +}
>> +
>> static void test_vm_type_gmem_flag_validity(unsigned long vm_type,
>> uint64_t expected_valid_flags)
>> {
>> - size_t page_size = getpagesize();
>> struct kvm_vm *vm;
>> uint64_t flag = 0;
>> - int fd;
>>
>> if (!(kvm_check_cap(KVM_CAP_VM_TYPES) & BIT(vm_type)))
>> return;
>> @@ -415,17 +433,11 @@ static void test_vm_type_gmem_flag_validity(unsigned long vm_type,
>> vm = vm_create_barebones_type(vm_type);
>>
>> for (flag = BIT(0); flag; flag <<= 1) {
>> - fd = __vm_create_guest_memfd(vm, page_size, flag);
>> + test_vm_with_gmem_flag(vm, flag, flag & expected_valid_flags);
>>
>> - if (flag & expected_valid_flags) {
>> - TEST_ASSERT(fd > 0,
>> - "guest_memfd() with flag '0x%lx' should be valid",
>> - flag);
>> - close(fd);
>> - } else {
>> - TEST_ASSERT(fd == -1 && errno == EINVAL,
>> - "guest_memfd() with flag '0x%lx' should fail with EINVAL",
>> - flag);
>> + if (flag == GUEST_MEMFD_FLAG_SUPPORT_SHARED) {
>> + test_vm_with_gmem_flag(
>> + vm, flag | GUEST_MEMFD_FLAG_INIT_PRIVATE, true);
>
> I don't understand the point of this check. In 2/51 we set
> GUEST_MEMFD_FLAG_INIT_PRIVATE when GUEST_MEMFD_FLAG_SUPPORT_SHARED is set.
>
> When can this check ever fail?
>
> Ira
In 02/51, GUEST_MEMFD_FLAG_INIT_PRIVATE is not set by default,
GUEST_MEMFD_FLAG_INIT_PRIVATE is set as one of the valid_flags.
The intention is that GUEST_MEMFD_FLAG_INIT_PRIVATE is only valid if
GUEST_MEMFD_FLAG_SUPPORT_SHARED is requested by userspace.
In this test, the earlier part before the if block calls
test_vm_with_gmem_flag() all valid flags, and that already tests
GUEST_MEMFD_FLAG_SUPPORT_SHARED individually.
Specifically if GUEST_MEMFD_FLAG_SUPPORT_SHARED is set, this if block
adds a test for when both GUEST_MEMFD_FLAG_SUPPORT_SHARED and
GUEST_MEMFD_FLAG_INIT_PRIVATE are set, and sets that expect_valid is
true.
This second test doesn't fail, it is meant to check that the kernel
allows the pair of flags to be set. Hope that makes sense.
