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

David Hildenbrand
2024-10-25T10:54:37Z

On 15.10.24 09:57, Claudio Imbrenda wrote:
> On Mon, 14 Oct 2024 20:56:59 +0200
> Heiko Carstens <hca@linux.ibm.com> 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 :)

I'll be sending a v3 later today, and a v1 of kdump support (which
involves a bunch of changes to fs/proc/vmcore.c and virtio-mem) separately.

--
Cheers,

David / dhildenb