This series has been successfully tested along with the QEMU's series. Virtio-mem devices could be resized, plugged and unplugged seamlessly. The memory information displayed is correct and reboot doesn't cause any issue. Tested-by: Mario Casquero <mcasquer@xxxxxxxxxx> On Tue, Sep 10, 2024 at 9:16 PM David Hildenbrand <david@xxxxxxxxxx> wrote: > > Let's finally add s390x support for virtio-mem; my last RFC was sent > 4 years ago, and a lot changed in the meantime. > > This is based on mm/stable. > > I sent out the QEMU part earlier today [1], that contains some more details > and a usage example on s390x (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". Once this > and the QEMU part will go upstream, it will get documented in [2] > > 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 [3]. > > 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. I > am working on a prototype that will be fairly straight forward, > because the virtio-mem driver already supports a special kdump mode and > dracut will already include it in the initrd as default. With > holiday and conferences coming up I rather sent this out now. > > [1] https://lkml.kernel.org/r/20240910175809.2135596-1-david@xxxxxxxxxx > [2] https://gitlab.com/davidhildenbrand/s390x-os-virt-spec > [3] https://virtio-mem.gitlab.io/user-guide/user-guide-linux.html > > Cc: Heiko Carstens <hca@xxxxxxxxxxxxx> > Cc: Vasily Gorbik <gor@xxxxxxxxxxxxx> > Cc: Alexander Gordeev <agordeev@xxxxxxxxxxxxx> > Cc: Christian Borntraeger <borntraeger@xxxxxxxxxxxxx> > Cc: Sven Schnelle <svens@xxxxxxxxxxxxx> > Cc: Thomas Huth <thuth@xxxxxxxxxx> > Cc: Cornelia Huck <cohuck@xxxxxxxxxx> > Cc: Janosch Frank <frankja@xxxxxxxxxxxxx> > Cc: Claudio Imbrenda <imbrenda@xxxxxxxxxxxxx> > Cc: "Michael S. Tsirkin" <mst@xxxxxxxxxx> > Cc: Jason Wang <jasowang@xxxxxxxxxx> > Cc: Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx> > Cc: "Eugenio Pérez" <eperezma@xxxxxxxxxx> > Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > > David Hildenbrand (5): > s390/kdump: implement is_kdump_kernel() > s390/physmem_info: query diag500(STORAGE_LIMIT) to support QEMU/KVM > memory devices > virtio-mem: s390x support > lib/Kconfig.debug: default STRICT_DEVMEM to "y" on s390x > s390/sparsemem: reduce section size to 128 MiB > > arch/s390/boot/physmem_info.c | 46 ++++++++++++++++++++++++++-- > arch/s390/include/asm/kexec.h | 4 +++ > arch/s390/include/asm/physmem_info.h | 3 ++ > arch/s390/include/asm/sparsemem.h | 2 +- > arch/s390/kernel/crash_dump.c | 6 ++++ > drivers/virtio/Kconfig | 12 ++++---- > lib/Kconfig.debug | 2 +- > 7 files changed, 64 insertions(+), 11 deletions(-) > > -- > 2.46.0 > >
