Re: [PATCH v2 00/14] s390x: virtio-mem support

[Christian Borntraeger]

Am 16.12.24 um 22:18 schrieb David Hildenbrand:
> Thanks, queued to
>
> https://github.com/davidhildenbrand/qemu.git mem-next
> On 13.12.24 15:26, David Hildenbrand wrote:
> > On 13.12.24 13:35, Thomas Huth wrote:
> > > On 12/12/2024 22.52, David Hildenbrand wrote:
> > > > On 13.11.24 15:46, David Hildenbrand wrote:
> > > > > On 08.10.24 12:54, David Hildenbrand wrote:
> > > > > > Based on current master.
> > > > > >
> > > > > > There is really not much left to do on s390x, because virtio-mem already
> > > > > > implements most things we need today (e.g., early-migration,
> > > > > > unplugged-inaccessible). The biggest part of this series is just doing what
> > > > > > we do with virtio-pci, wiring it up in the machine hotplug handler and ...
> > > > > > well, messing with the physical memory layout where we can now exceed
> > > > > > initial RAM size and have sparsity (memory holes).
> > > > > >
> > > > > > I tested a lot of things, including:
> > > > > >      * Memory hotplug/unplug
> > > > > >      * Device hotplug/unplug
> > > > > >      * System resets / reboots
> > > > > >      * Migrate to/from file (including storage attributes under KVM)
> > > > > >      * Basic live migration
> > > > > >      * Basic postcopy live migration
> > > > > >
> > > > > > More details on how to use it on s390x -- which is pretty much how
> > > > > > we use it on other architectures, except
> > > > > > s/virtio-mem-pci/virtio-mem-ccw/ --- is in the last patch.
> > > > > >
> > > > > > This series introduces a new diag(500) "STORAGE LIMIT" subcode that will
> > > > > > be documented in the kernel and at [2] once this+kernel part go upstream.
> > > > > >
> > > > > > There are not many s390x-specific virtio-mem future work items, except:
> > > > > > * Storage attribute migration might be improved
> > > > > > * We might want to reset storage attributes of unplugged memory
> > > > > >       (might or might not be required for upcoming page table reclaim in
> > > > > >        Linux; TBD)
> > > > > >
> > > > > > The Linux driver is available at [3].
> > > > > >
> > > > > > [1] https://lkml.kernel.org/r/20240906101658.514470-1-pbonzini@redhat.com
> > > > > > [2] https://gitlab.com/davidhildenbrand/s390x-os-virt-spec
> > > > > > [3] https://lkml.kernel.org/r/20240910191541.2179655-6-david@redhat.com
> > > > >
> > > > > Gentle ping (and thanks to Thomas for the review!).
> > > > >
> > > > > I assume the kernel portion will go upstream in the next merge window.
> > > > > I'd like get the QEMU parts merged soon after that.
> > > > >
> > > > > 9.2 is going to get released in roughly one month, so there is still time.
> > > >
> > > > In the meantime, 9.2 was released. I don't have any changes planned. Series
> > > > still applies to current master, I'll do a quick test tomorrow.
> > > >
> > > > > @Thomas, this is mostly s390x stuff, so I guess it should go through the
> > > > > s390x tree? But I could also take this through my "memory devices" tree.
> > > >
> > > > @Thomas, any thoughts?
> > >
> > > I'm fine either way - feel free to put it into your tree, otherwise I'll
> > > pick it up likely sometime next week.
> >
> > Okay, let me let this sit here for a couple days longer and retest it
> > next week. I can queue it then, as another required patch ("virtio-mem:
> > unplug memory only during system resets, not device resets") still sits
> > in my tree all-lonely. :)
>
> Testing revealed no surprised.
>
> Queued to
>
> https://github.com/davidhildenbrand/qemu.git mem-next

Thank you for doing it. Awesome work.