Re: [PATCH v2 0/7] virtio-mem: s390 support

[Claudio Imbrenda]

On Mon, 14 Oct 2024 20:56:59 +0200
Heiko Carstens <hca@xxxxxxxxxxxxx> wrote:

> On Mon, Oct 14, 2024 at 04:46:12PM +0200, David Hildenbrand wrote:
> > Let's finally add s390 support for virtio-mem; my last RFC was sent
> > 4 years ago, and a lot changed in the meantime.
> > 
> > The latest QEMU series is available at [1], which contains some more
> > details and a usage example on s390 (last patch).
> > 
> > There is not too much in here: The biggest part is querying a new diag(500)
> > STORAGE_LIMIT hypercall to obtain the proper "max_physmem_end".
> > 
> > The last two patches are not strictly required but certainly nice-to-have.
> > 
> > Note that -- in contrast to standby memory -- virtio-mem memory must be
> > configured to be automatically onlined as soon as hotplugged. The easiest
> > approach is using the "memhp_default_state=" kernel parameter or by using
> > proper udev rules. More details can be found at [2].
> > 
> > I have reviving+upstreaming a systemd service to handle configuring
> > that on my todo list, but for some reason I keep getting distracted ...
> > 
> > I tested various things, including:
> >  * Various memory hotplug/hotunplug combinations
> >  * Device hotplug/hotunplug
> >  * /proc/iomem output
> >  * reboot
> >  * kexec
> >  * kdump: make sure we don't hotplug memory
> > 
> > One remaining work item is kdump support for virtio-mem memory. This will
> > be sent out separately once initial support landed.  
> 
> Besides the open kdump question, which I think is quite important, how
> is this supposed to go upstream?
> 
> This could go via s390, however in any case this needs reviews and/or
> Acks from kvm folks.

we're working on it :)