Re: [PATCH RESEND v2 0/5] virtio-mem: VIRTIO_MEM_F_UNPLUGGED_INACCESSIBLE and interaction with memory properties

[Cornelia Huck <cohuck@redhat.com>]

On Mon, Sep 20 2021, David Hildenbrand <david@redhat.com> wrote:

> Looking into supporting virtio-mem
> a) without a shared zeropage for the memory backing of the device --
>    not allowing the driver to read unplugged memory
> b) on architectures with memory properties for RAM (e.g., s390x with
>    storage keys and storage attributes)
> requires extension of the spec to handle both cases cleanly and describe
> the expected semantics.
>
> I'll open a github issue soon; in the meantime, I'll work on the actual
> implementation in QEMU and Linux.

LGTM, but would like a second opinion.

>
> For a), I already shared a Linux implementation in the past [1], which will
> be simplified once virito-mem memory can no longer be mapped via /dev/mem
> [2].
>
> For b), it's actually unlocking virtio-mem on s390x in QEMU/Linux,
> initially supporting storage keys but not supporting storage attributes
> for simplicity.
>
> [1] https://lkml.kernel.org/r/20210215122421.27964-1-david@redhat.com
> [2] https://lkml.kernel.org/r/20210902160919.25683-1-david@redhat.com