On 14.10.24 20:56, Heiko Carstens 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?
MST suggested via the s390 tree in v1.
This could go via s390, however in any case this needs reviews and/or
Acks from kvm folks.
Yes, hoping there will be some review (there was some on the QEMU series).
--
Cheers,
David / dhildenb
