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Message-ID: <20240910191541.2179655-1-david@redhat.com>
Date: Tue, 10 Sep 2024 21:15:34 +0200
From: David Hildenbrand <david@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: linux-mm@...ck.org,
linux-s390@...r.kernel.org,
virtualization@...ts.linux.dev,
David Hildenbrand <david@...hat.com>,
Heiko Carstens <hca@...ux.ibm.com>,
Vasily Gorbik <gor@...ux.ibm.com>,
Alexander Gordeev <agordeev@...ux.ibm.com>,
Christian Borntraeger <borntraeger@...ux.ibm.com>,
Sven Schnelle <svens@...ux.ibm.com>,
Thomas Huth <thuth@...hat.com>,
Cornelia Huck <cohuck@...hat.com>,
Janosch Frank <frankja@...ux.ibm.com>,
Claudio Imbrenda <imbrenda@...ux.ibm.com>,
"Michael S. Tsirkin" <mst@...hat.com>,
Jason Wang <jasowang@...hat.com>,
Xuan Zhuo <xuanzhuo@...ux.alibaba.com>,
Eugenio Pérez <eperezma@...hat.com>,
Andrew Morton <akpm@...ux-foundation.org>
Subject: [PATCH v1 0/5] virtio-mem: s390x support
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@redhat.com
[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@...ux.ibm.com>
Cc: Vasily Gorbik <gor@...ux.ibm.com>
Cc: Alexander Gordeev <agordeev@...ux.ibm.com>
Cc: Christian Borntraeger <borntraeger@...ux.ibm.com>
Cc: Sven Schnelle <svens@...ux.ibm.com>
Cc: Thomas Huth <thuth@...hat.com>
Cc: Cornelia Huck <cohuck@...hat.com>
Cc: Janosch Frank <frankja@...ux.ibm.com>
Cc: Claudio Imbrenda <imbrenda@...ux.ibm.com>
Cc: "Michael S. Tsirkin" <mst@...hat.com>
Cc: Jason Wang <jasowang@...hat.com>
Cc: Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
Cc: "Eugenio Pérez" <eperezma@...hat.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
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
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