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

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On 31.10.24 17:47, Sumanth Korikkar wrote:
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@xxxxxxxxxx
[2] https://virtio-mem.gitlab.io/user-guide/user-guide-linux.html
[3] https://lkml.kernel.org/r/20241023090651.1115507-1-david@xxxxxxxxxx

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 P?rez" <eperezma@xxxxxxxxxx>
Cc: Eric Farman <farman@xxxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Jonathan Corbet <corbet@xxxxxxx>

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.

Thanks a bunch!

--
Cheers,

David / dhildenb





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