[Qemu-devel] [PATCH for-2.7 v6 0/2] ispapr: QMP: add query-hotpluggable-cpus

[Igor Mammedov <imammedo@redhat.com>]

Changes since v4:
 - fix style issues in qapi-schema and qmp-commands,
   Eric Blake <eblake@redhat.com>
 - rebase on top current master (fix query-gic-capabilities conflict)
 - fix s390 build failure:
    undefined reference to `qmp_query_hotpluggable_cpus'
Changes since v3:
 - replace qmp_query_hotpluggable_cpus with MachineClass->query_hotpluggable_cpus
   callback. (Eduardo Habkost <ehabkost@redhat.com>)
 - fix cover letter to explain why new command is needed.
   (Markus Armbruster <armbru@redhat.com>)
Changes since v2:
 - rebase on top of hte lates spapr cpu hotpug series
 - add 'vcpus-count' field, pkrempa@redhat.com
 - s/CpuInstanceProps/CpuInstanceProperties/
 - use '#optional' marker
 - make "props" as always present even if it's empty
 - fix JSON examples
 - fix minor typos
 - drop pre_plug spapr impl out of series as not related to QMP command
 - drop generic pre hotplug callback as not related to QMP command

Changes since RFC:
 - drop arch_id
 - move CPU properties into separate structure
 - target implements its own qmp callback version
 - rebased on top of [RFC PATCH v1 00/10] Core based CPU hotplug for PowerPC sPAPR
                      https://www.mail-archive.com/qemu-devel@nongnu.org/msg357567.html
    - convert slot name to core id hack
    - drop links
    - add generic pre hotplug callback
    - implement query-hotpluggable-cpus

Series adds query-hotpluggable-cpus QMP command to allow mgmt
query board specific configuration of possible CPU objects
with their properties, which is target specific and also
depends on CLI options (like -smp/-cpu/-numa).
Returned information includes QOM type of CPU objects and
a set of properties that are necessary for hotplugging them.
Information will be used with device_add/-device when
hotplugging a CPU and migrating QEMU instance with hotplugged CPUs.

PS:
The first patch (QMP API) in this series could go in first
allowing individual targets to post their hotplug
implementation independently on top of it.

PS2:
Summary on QMP vs QOM interface discussion:

a QMP command is
 1. a single / atomic command 
 2. well documented
 3. fixed at compile time/staic so it's easy for mgmt to discover it.

while a considered alternative QOM interface via qom-get(path) is
 1. not atomic, i.e. requires a lot of qom-get requests over the wire
    to traverse QOM tree and fetch information
 2. not documented
 3. dynamically generated and would require more complicated coding
    even to create a simplistic interface similar to proposed QMP command
    (for example: possible_cpu QOM objects with a related properties)



Igor Mammedov (2):
  QMP: add query-hotpluggable-cpus
  spapr: implement query-hotpluggable-cpus callback

 hw/ppc/spapr.c      | 33 +++++++++++++++++++++++++++++++++
 include/hw/boards.h |  5 +++++
 monitor.c           | 13 +++++++++++++
 qapi-schema.json    | 46 ++++++++++++++++++++++++++++++++++++++++++++++
 qmp-commands.hx     | 41 +++++++++++++++++++++++++++++++++++++++++
 5 files changed, 138 insertions(+)

-- 
1.8.3.1