Re: [PATCH v1 00/14] s390x: virtio-mem support

[Michael S. Tsirkin]

On Tue, Sep 10, 2024 at 07:57:55PM +0200, David Hildenbrand wrote:
> This series is based on:
>     [PATCH v2] virtio: kconfig: memory devices are PCI only [1]
> 
> I finally found the time (IOW forced myself) to finish virtio-mem
> support on s390x. The last RFC was from 2020, so I won't talk about
> what changed -- a lot changed in the meantime :)
> 
> 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 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)


I don't see anything needing virtio specific here, let me know if
I missed anything.
A quick look is fine so I guess you can add
Acked-by: Michael S. Tsirkin <mst@redhat.com>



> I'll send out the kernel driver bits soon.
> 
> [1] https://lkml.kernel.org/r/20240906101658.514470-1-pbonzini@redhat.com
> [2] https://gitlab.com/davidhildenbrand/s390x-os-virt-spec
> 
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: Thomas Huth <thuth@redhat.com>
> Cc: Halil Pasic <pasic@linux.ibm.com>
> Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
> Cc: Eric Farman <farman@linux.ibm.com>
> Cc: Richard Henderson <richard.henderson@linaro.org>
> Cc: David Hildenbrand <david@redhat.com>
> Cc: Ilya Leoshkevich <iii@linux.ibm.com>
> Cc: Janosch Frank <frankja@linux.ibm.com>
> Cc: "Michael S. Tsirkin" <mst@redhat.com>
> Cc: Cornelia Huck <cohuck@redhat.com>
> 
> David Hildenbrand (14):
>   s390x/s390-virtio-ccw: don't crash on weird RAM sizes
>   s390x/s390-virtio-hcall: remove hypercall registration mechanism
>   s390x/s390-virtio-hcall: prepare for more diag500 hypercalls
>   s390x: rename s390-virtio-hcall* to s390-hypercall*
>   s390x/s390-virtio-ccw: move setting the maximum guest size from sclp
>     to machine code
>   s390x: introduce s390_get_memory_limit()
>   s390x/s390-hypercall: introduce DIAG500 STORAGE_LIMIT
>   s390x/s390-stattrib-kvm: prepare memory devices and sparse memory
>     layouts
>   s390x/s390-skeys: prepare for memory devices
>   s390x/pv: check initial, not maximum RAM size
>   s390x/s390-virtio-ccw: prepare for memory devices
>   s390x: introduce s390_get_max_pagesize()
>   s390x/virtio-ccw: add support for virtio based memory devices
>   s390x: virtio-mem support
> 
>  MAINTAINERS                    |   4 +
>  hw/s390x/Kconfig               |   1 +
>  hw/s390x/meson.build           |   4 +-
>  hw/s390x/s390-hypercall.c      |  77 +++++++++++
>  hw/s390x/s390-hypercall.h      |  25 ++++
>  hw/s390x/s390-skeys.c          |   4 +-
>  hw/s390x/s390-stattrib-kvm.c   |  63 +++++----
>  hw/s390x/s390-virtio-ccw.c     | 143 +++++++++++++--------
>  hw/s390x/s390-virtio-hcall.c   |  41 ------
>  hw/s390x/s390-virtio-hcall.h   |  25 ----
>  hw/s390x/sclp.c                |  17 +--
>  hw/s390x/virtio-ccw-md.c       | 153 ++++++++++++++++++++++
>  hw/s390x/virtio-ccw-md.h       |  44 +++++++
>  hw/s390x/virtio-ccw-mem.c      | 226 +++++++++++++++++++++++++++++++++
>  hw/s390x/virtio-ccw-mem.h      |  34 +++++
>  hw/virtio/Kconfig              |   1 +
>  hw/virtio/virtio-mem.c         |   4 +-
>  target/s390x/cpu-sysemu.c      |  35 ++++-
>  target/s390x/cpu.h             |   2 +
>  target/s390x/kvm/kvm.c         |  12 +-
>  target/s390x/kvm/pv.c          |   2 +-
>  target/s390x/tcg/misc_helper.c |   6 +-
>  22 files changed, 746 insertions(+), 177 deletions(-)
>  create mode 100644 hw/s390x/s390-hypercall.c
>  create mode 100644 hw/s390x/s390-hypercall.h
>  delete mode 100644 hw/s390x/s390-virtio-hcall.c
>  delete mode 100644 hw/s390x/s390-virtio-hcall.h
>  create mode 100644 hw/s390x/virtio-ccw-md.c
>  create mode 100644 hw/s390x/virtio-ccw-md.h
>  create mode 100644 hw/s390x/virtio-ccw-mem.c
>  create mode 100644 hw/s390x/virtio-ccw-mem.h
> 
> -- 
> 2.46.0