On 15.10.24 09:57, Claudio Imbrenda wrote:
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 :)
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
