[Qemu-devel] [PATCH RFCv2 0/9] qdev: Hotplug handler chaining + virtio-pmem

[David Hildenbrand <david@redhat.com>]

This series implements supprt for hotplug handler chaining (proposed
by Igor), something that is necessary to turn selected virtio devices into
memory devices. Planned devices inlude virtio-mem and virtio-pmem. The
current prototype of virtio-pmem is included.

The machine hotplug handler can intercept hotplug handler calls
to properly prepare/teardown the memory device part of a device. Control
is then passed on to the actual bus hotplug handler. So the default hotplug
handler is effectively overwritten to make interception possible.

It is based on the following patches/series
- [PATCH v1] pc: Use hotplug_handler_(plug|unplug|unplug_request)
-- Queued by Paolo
- [PATCH v3 0/2] s390x/pci: hotplug handler fixes and reworks

Patch 1-3 are the preparations for hotplug handler chaining. The remaining
patches are a modified prototype of virtio-pmem.

TODO:
- More testing for patch #1 + eventually write some unplug tests
- Pankaj has to fixup some things in "virtio-pmem: Prototype"
-- See patch description for details

I modified Pankajs work to work with this series. virtio-pmem is included
as it was requested during review of previous preparations to showcase a
real user, so we can discuss if this is good enough for us or if we have
to do further changes.

More details about virtio-pmem (including the Linux guest driver side)
can be found at:
    https://lkml.org/lkml/2018/7/13/102
    https://lkml.org/lkml/2019/1/9/756

Example: defining a simple virtio-pmem device (on /dev/zero for simplicity):

    qemu-system-x86_64 \
     -machine pc \
     -monitor stdio \
     -m 8G,maxmem=20G \
     -object memory-backend-file,id=mem1,mem-path=/dev/zero,size=4G \
     -device virtio-pmem-pci,id=vp1,memdev=mem1

QEMU 3.0.50 monitor - type 'help' for more information
(qemu) info memory-devices
Memory device [virtio-pmem]: "vp1"
  memaddr: 0x240000000
  size: 4294967296
  memdev: /objects/mem1

(qemu) info memory_size_summary
base memory: 8589934592
plugged memory: 4294967296

RFC -> RFCv2
- "virtio-pmem: Prototype"
- Minor documentation/style changes
- "virtio-pci: Proxy for virtio-pmem"
-- Separate header file virtio-pmem-pci.h
- "pc: Support for virtio-pmem-pci"
-- Only handle virtio-pmem-pci specially


David Hildenbrand (6):
  qdev: Let the hotplug_handler_unplug() caller delete the device
  qdev: Provide qdev_get_bus_hotplug_handler()
  virtio-pci: Allow to specify additional interfaces for the base type
  hmp: Handle virtio-pmem when printing memory device infos
  numa: Handle virtio-pmem in NUMA stats
  pc: Support for virtio-pmem-pci

Igor Mammedov (1):
  qdev: Let machine hotplug handler to override bus hotplug handler

Pankaj Gupta (2):
  virtio-pmem: Prototype
  virtio-pci: Proxy for virtio-pmem

 default-configs/i386-softmmu.mak            |   1 +
 hmp.c                                       |  27 +--
 hw/acpi/cpu.c                               |   1 +
 hw/acpi/memory_hotplug.c                    |   1 +
 hw/acpi/pcihp.c                             |   3 +-
 hw/core/qdev.c                              |  19 +-
 hw/i386/pc.c                                |  75 +++++++-
 hw/pci/pcie.c                               |   3 +-
 hw/pci/shpc.c                               |   3 +-
 hw/ppc/spapr.c                              |   4 +-
 hw/ppc/spapr_pci.c                          |   3 +-
 hw/s390x/css-bridge.c                       |   2 +-
 hw/s390x/s390-pci-bus.c                     |  13 +-
 hw/virtio/Makefile.objs                     |   3 +
 hw/virtio/virtio-pci.c                      |   1 +
 hw/virtio/virtio-pci.h                      |   1 +
 hw/virtio/virtio-pmem-pci.c                 | 144 +++++++++++++++
 hw/virtio/virtio-pmem-pci.h                 |  39 ++++
 hw/virtio/virtio-pmem.c                     | 191 ++++++++++++++++++++
 include/hw/qdev-core.h                      |  12 ++
 include/hw/virtio/virtio-pmem.h             |  54 ++++++
 include/standard-headers/linux/virtio_ids.h |   1 +
 numa.c                                      |  24 +--
 qapi/misc.json                              |  28 ++-
 qdev-monitor.c                              |   9 +-
 25 files changed, 612 insertions(+), 50 deletions(-)
 create mode 100644 hw/virtio/virtio-pmem-pci.c
 create mode 100644 hw/virtio/virtio-pmem-pci.h
 create mode 100644 hw/virtio/virtio-pmem.c
 create mode 100644 include/hw/virtio/virtio-pmem.h

-- 
2.17.2