Re: [PATCH v4 11/11] KVM: selftests: Add guest_memfd_preservation_test

Tarun Sahu <[email protected]> writes:

> Add guest_memfd_preservation_test to verify that KVM VM state and guest
> memory backed by guest_memfd are preserved across a kexec reboot via Live
> Update Orchestrator (LUO).
>
> This test includes multiple tests
> - (A) Test to preserve non-guest_memfd, non-memfd which must fail (/dev/null)
> - (B) Test to preserve guest_memfd with no INIT_SHARED flag which must fail
> - (C) Test to allocate the guest_memfd memory after preservation because
>   preservation makes the guest_memfd frozen. Which must fail as well.
> - (D) Test to verify guest_memfd with INIT_SHARED flag preservation across
>   kexec: Below is the details of stages in this test.
>

I think we should split this into multiple patches, where each patch
introduces 1 test.

>
> [...snip...]
>
> +++ b/tools/testing/selftests/kvm/guest_memfd_preservation_test.c
> @@ -0,0 +1,357 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2026, Google LLC.
> + *
> + * Author: Tarun Sahu <[email protected]>
> + *
> + * Test for VM and guest_memfd preservation across kexec (Live Update) via LUO.
> + *
> + * NOTE: This is a MANUAL test and is excluded from automated CI/testing
> + * frameworks because Stage 1 daemonizes into the background to pin resources
> + * and requires a human operator to manually trigger kexec before Stage 2
> + * is executed. Running Stage 1 automatically would leak the background daemon
> + * and cause CI runners to falsely interpret it as a passed test.
> + *

Usually there aren't many printfs in tests, but since this is a MANUAL
test, maybe that's ok?

Would like to know what Sean thinks of this, and printfs in general.

>
> [...snip...]
>