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

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

v1 -> v2:
* "s390x/s390-virtio-hcall: prepare for more diag500 hypercalls"
 - Turn handle_diag_500() into a void function
 - Inject PGM_SPECIFICATION from handle_diag_500() directly
* "s390x/s390-virtio-ccw: move setting the maximum guest size from sclp to
   machine code"
 - Move code to a new function to make further changes easier
 - Adjust s390_pv_vm_try_disable_async() to stay in sync with the
   maxram->ram change
* "s390x: introduce s390_get_memory_limit()"
 - Store limit in machine
 - Move s390_set_memory_limit() from target code into machine code
* "s390x/s390-hypercall: introduce DIAG500 STORAGE_LIMIT"
 - Move handling into a separate function now that we lookup the machine
* "s390x/s390-stattrib-kvm: prepare for memory devices and sparse memory
   layouts"
 - Adjust to s390_get_memory_limit() changes
* "s390x/s390-skeys: prepare for memory devices"
 - Adjust to s390_get_memory_limit() changes
* "s390x/pv: prepare for memory devices"
 - Use s390_get_memory_limit()
* "s390x: remember the maximum page size"
 - Store it in the machine
 - Move s390_set_max_pagesize() from target code into machine code
 - No need for s390_get_max_pagesize()
* "s390x/virtio-ccw: add support for virtio based memory devices"
 - Move machine wire-up code from virtio-mem patch into this patch
 - Add stubs to make compilation without virtio-mem work
* "s390x: virtio-mem support"
 - Move machine write-up code to previous patch

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: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.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 for memory devices and sparse memory
    layouts
  s390x/s390-skeys: prepare for memory devices
  s390x/s390-virtio-ccw: prepare for memory devices
  s390x/pv: prepare for memory devices
  s390x: remember the maximum page size
  s390x/virtio-ccw: add support for virtio based memory devices
  s390x: virtio-mem support

 MAINTAINERS                        |   5 +
 hw/s390x/Kconfig                   |   1 +
 hw/s390x/meson.build               |   6 +-
 hw/s390x/s390-hypercall.c          |  85 +++++++++++
 hw/s390x/s390-hypercall.h          |  25 ++++
 hw/s390x/s390-skeys.c              |   6 +-
 hw/s390x/s390-stattrib-kvm.c       |  67 ++++++---
 hw/s390x/s390-virtio-ccw.c         | 165 ++++++++++++++-------
 hw/s390x/s390-virtio-hcall.c       |  41 ------
 hw/s390x/s390-virtio-hcall.h       |  25 ----
 hw/s390x/sclp.c                    |  17 +--
 hw/s390x/virtio-ccw-md-stubs.c     |  24 +++
 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 +-
 include/hw/s390x/s390-virtio-ccw.h |   4 +
 target/s390x/cpu-sysemu.c          |  15 --
 target/s390x/cpu.h                 |   2 -
 target/s390x/kvm/kvm.c             |  18 +--
 target/s390x/kvm/pv.c              |   2 +-
 target/s390x/tcg/misc_helper.c     |   7 +-
 24 files changed, 782 insertions(+), 195 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-stubs.c
 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