Re: [PATCH v3 0/7] virtio-mem: s390 support

Sumanth Korikkar
2024-10-31T16:47:34Z

On Thu, Oct 31, 2024 at 05:27:06PM +0100, Sumanth Korikkar wrote:
> On Fri, Oct 25, 2024 at 04:14:45PM +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 three 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 properly enter the "kdump mode" in the virtio-mem
> > driver
> >
> > kdump support for virtio-mem memory on s390 will be sent out separately.
> >
> > v2 -> v3
> > * "s390/kdump: make is_kdump_kernel() consistently return "true" in kdump
> > environments only"
> > -> Sent out separately [3]
> > * "s390/physmem_info: query diag500(STORAGE LIMIT) to support QEMU/KVM memory
> > devices"
> > -> No query function for diag500 for now.
> > -> Update comment above setup_ident_map_size().
> > -> Optimize/rewrite diag500_storage_limit() [Heiko]
> > -> Change handling in detect_physmem_online_ranges [Alexander]
> > -> Improve documentation.
> > * "s390/sparsemem: provide memory_add_physaddr_to_nid() with CONFIG_NUMA"
> > -> Added after testing on systems with CONFIG_NUMA=y
> >
> > v1 -> v2:
> > * Document the new diag500 subfunction
> > * Use "s390" instead of "s390x" consistently
> >
> > [1] https://lkml.kernel.org/r/20241008105455.2302628-1-david@redhat.com
> > [2] https://virtio-mem.gitlab.io/user-guide/user-guide-linux.html
> > [3] https://lkml.kernel.org/r/20241023090651.1115507-1-david@redhat.com
> >
> > Cc: Heiko Carstens <hca@linux.ibm.com>
> > Cc: Vasily Gorbik <gor@linux.ibm.com>
> > Cc: Alexander Gordeev <agordeev@linux.ibm.com>
> > Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
> > Cc: Sven Schnelle <svens@linux.ibm.com>
> > Cc: Thomas Huth <thuth@redhat.com>
> > Cc: Cornelia Huck <cohuck@redhat.com>
> > Cc: Janosch Frank <frankja@linux.ibm.com>
> > Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
> > Cc: "Michael S. Tsirkin" <mst@redhat.com>
> > Cc: Jason Wang <jasowang@redhat.com>
> > Cc: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
> > Cc: "Eugenio P?rez" <eperezma@redhat.com>
> > Cc: Eric Farman <farman@linux.ibm.com>
> > Cc: Andrew Morton <akpm@linux-foundation.org>
> > Cc: Jonathan Corbet <corbet@lwn.net>
> >
> > David Hildenbrand (7):
> > Documentation: s390-diag.rst: make diag500 a generic KVM hypercall
> > Documentation: s390-diag.rst: document diag500(STORAGE LIMIT)
> > subfunction
> > s390/physmem_info: query diag500(STORAGE LIMIT) to support QEMU/KVM
> > memory devices
> > virtio-mem: s390 support
> > lib/Kconfig.debug: default STRICT_DEVMEM to "y" on s390
> > s390/sparsemem: reduce section size to 128 MiB
> > s390/sparsemem: provide memory_add_physaddr_to_nid() with CONFIG_NUMA
> >
> > Documentation/virt/kvm/s390/s390-diag.rst | 35 +++++++++++++----
> > arch/s390/boot/physmem_info.c | 47 ++++++++++++++++++++++-
> > arch/s390/boot/startup.c | 7 +++-
> > arch/s390/include/asm/physmem_info.h | 3 ++
> > arch/s390/include/asm/sparsemem.h | 10 ++++-
> > drivers/virtio/Kconfig | 12 +++---
> > lib/Kconfig.debug | 2 +-
> > 7 files changed, 98 insertions(+), 18 deletions(-)
> >
> >
> > base-commit: ae90f6a6170d7a7a1aa4fddf664fbd093e3023bc
> > --
> > 2.46.1
> >
>
> Tested successfully various memory hotplug operations on lpar.
>
Just to be more precise, tested memory hotplug/hotunplug combinations +
Device hotplug/hotunplug operations on guest.

> Tested-by: Sumanth Korikkar <sumanthk@linux.ibm.com>