Re: [PATCH v10 40/41] KVM: selftests: Update private_mem_conversions_test to mmap() guest_memfd

[Ackerley Tng]

Sean Christopherson <seanjc@xxxxxxxxxx> writes:

> On Fri, Aug 21, 2026, Xiaoyao Li wrote:
>> On 8/8/2026 5:53 AM, Ackerley Tng via B4 Relay wrote:
>> > From: Ackerley Tng<ackerleytng@xxxxxxxxxx>
>> >
>> > Update the private memory conversions selftest to also test conversions
>> > that are done "in-place" via per-guest_memfd memory attributes. In-place
>> > conversions require the host to be able to mmap() the guest_memfd so that
>> > the host and guest can share the same backing physical memory.
>> >
>> > This includes several updates, that are conditioned on the system
>> > supporting per-guest_memfd attributes (kvm_has_gmem_attributes):
>> >
>> > 1. Set up guest_memfd requesting MMAP and INIT_SHARED.
>>
>> If I understand correctly, even with in-place gmem, the model that shared
>> memory comes from the userspace_addr and private memory comes from gmem can
>> still work without passing GUEST_MEMFD_FLAG_MMAP flag.
>>
>> Since this model is not prohibited by KVM. I think we should keep the
>> testcase for this model to ensure test coverage?
>
> +1.  Deprecated doesn't mean unsupported.

The original test case was for non-in-place conversion, which wasn't
removed, it still passes.

Is the ask to also test, under kvm_has_gmem_attributes aka
gmem_in_place_conversion, to have guest_memfd used as purely for private
memory and have shared memory taken from somewhere else completely?

I can rephrase the changelog and change the code to clarify that this
patch is meant to specifically test in-place conversion with MMAP, the
intended usage of in-place conversions.

The ask to test gmem for private and something else for shared seems
like a different test that can be added separately, perhaps in a
follow-up series?