QEMU has a monitor command 'set_cpu' which allows a specific
CPU to be toggled between online& offline state. libvirt CPU
hotplug does not work in terms of individual indexes CPUs.
Thus to support this, we iteratively toggle the online state
when the total number of vCPUs is adjusted via libvirt

NB, currently untested since QEMU segvs when running this!

* src/qemu/qemu_driver.c: Toggle online state for CPUs when
  doing hotplug
* src/qemu/qemu_monitor.c, src/qemu/qemu_monitor.h,
  src/qemu/qemu_monitor_json.c, src/qemu/qemu_monitor_json.h,
  src/qemu/qemu_monitor_text.c, src/qemu/qemu_monitor_text.h: Add
  monitor API for toggling a CPU's online status via 'set_cpu

The QMP code was running query-migration instead of query-migrate.
This doesn't work so well

* src/qemu/qemu_monitor_json.c: s/query-migration/query-migrate/

when the underlying qemu supports the drive/device model and the
controller has been added this way.
* src/qemu/qemu_driver.c: use qemuMonitorDelDevice() when detaching
  PCI controller and if supported
* src/qemu/qemu_monitor.[ch]: add new qemuMonitorDelDevice() function
* src/qemu/qemu_monitor_json.[ch]: JSON backend for DelDevice command
* src/qemu/qemu_monitor_text.[ch]: Text backend for DelDevice command

The QEMU JSON monitor changed balloon commands to return/accept
bytes instead of kilobytes. Update libvirt to cope with this

* src/qemu/qemu_monitor_json.c: Expect/use bytes for ballooning

The plain QEMU tree does not include 'thread_id' in the JSON
output. Thus we need to treat it as non-fatal if missing.

* src/qemu/qemu_monitor_json.c: Treat missing thread_id as non-fatal

Current error reporting for JSON mode returns the full JSON
command string and full JSON error string. This is not very
user friendly, so this change makes the error report only
contain the basic command name, and friendly error message
description string. The full JSON data is logged instead.

* src/qemu/qemu_monitor_json.c: Always return the 'desc' field from
  the JSON error message to users.

When in JSON mode, QEMU requires that 'qmp_capabilities' is run as
the first command in the monitor. This is a no-op when run in the
text mode monitor

* src/qemu/qemu_driver.c: Run capabilities negotiation when
  connecting to the monitor
* src/qemu/qemu_monitor.c, src/qemu/qemu_monitor.h,
  src/qemu/qemu_monitor_json.c, src/qemu/qemu_monitor_json.h: Add
  support for the 'qmp_capabilities' command, no-op in text mode.

The old text mode monitor prompts for a password when disks are
encrypted. This interactive approach doesn't work for JSON mode
monitor. Thus there is a new 'block_passwd' command that can be
used.

* src/qemu/qemu_driver.c: Split out code for looking up a disk
  secret from findVolumeQcowPassphrase, into a new method
  getVolumeQcowPassphrase. Enhance qemuInitPasswords() to also
  set the disk encryption password via the monitor
* src/qemu/qemu_monitor.c, src/qemu/qemu_monitor.h,
  src/qemu/qemu_monitor_json.c, src/qemu/qemu_monitor_json.h,
  src/qemu/qemu_monitor_text.c, src/qemu/qemu_monitor_text.h: Add
  support for the 'block_passwd' monitor command.

With QEMU >= 0.12 the host and guest side of disks no longer have
the same naming convention. Specifically the host side will now
get a 'drive-' prefix added to its name. The 'info blockstats'
monitor command returns the host side name, so it is neccessary
to strip this off when looking up stats since libvirt stores the
guest side name !

* src/qemu/qemu_conf.c, src/qemu/qemu_conf.h: Move 'drive-' prefix
  string to a defined constant
* src/qemu/qemu_monitor_json.c, src/qemu/qemu_monitor_text.c: Strip
  off 'drive-' prefix (if found) when looking up disk stats

The way QEMU is started has been changed to use '-device' and
the new style '-drive' syntax. This needs to be mirrored in
the hotplug code, requiring addition of two new APIs.

* src/qemu/qemu_monitor.h, src/qemu/qemu_monitor.c: Define APIs
  qemuMonitorAddDevice() and qemuMonitorAddDrive()
* src/qemu/qemu_monitor_json.c, src/qemu/qemu_monitor_json.h,
  src/qemu/qemu_monitor_text.c, src/qemu/qemu_monitor_text.h:
  Implement the new monitor APIs

The KVM build of QEMU includs the thread ID of each vCPU in the
'query-cpus' output. This is required for pinning guests to
particular host CPUs

* src/qemu/qemu_monitor_json.c: Extract 'thread_id' from CPU info

* src/util/json.c, src/util/json.h: Declare returned strings
  to be const
* src/qemu/qemu_monitor.c: Wire up JSON mode for qemuMonitorGetPtyPaths
* src/qemu/qemu_monitor_json.c, src/qemu/qemu_monitor_json.h: Fix
  const correctness. Add missing error message in the function
  qemuMonitorJSONGetAllPCIAddresses. Add implementation of the
  qemuMonitorGetPtyPaths function calling 'query-chardev'.

* src/qemu/qemu_conf.c (qemuBuildDriveStr): Use "%s".
* src/qemu/qemu_monitor_json.c (qemuMonitorJSONGetGuestPCIAddress):
(qemuMonitorJSONGetGuestDriveAddress): Likewise.

Hotunplug of devices requires that we know their PCI address. Even
hotplug of SCSI drives, required that we know the PCI address of
the SCSI controller to attach the drive to. We can find this out
by running 'info pci' and then correlating the vendor/product IDs
with the devices we booted with.

Although this approach is somewhat fragile, it is the only viable
option with QEMU < 0.12, since there is no way for libvirto set
explicit PCI addresses when creating devices in the first place.
For QEMU > 0.12, this code will not be used.

* src/qemu/qemu_driver.c: Assign all dynamic PCI addresses on
  startup of QEMU VM, matching vendor/product IDs
* src/qemu/qemu_monitor.c, src/qemu/qemu_monitor.h,
  src/qemu/qemu_monitor_json.c, src/qemu/qemu_monitor_json.h,
  src/qemu/qemu_monitor_text.c, src/qemu/qemu_monitor_text.h: Add
  API for fetching PCI device address mapping

The current SCSI hotplug support attaches a brand new SCSI controller
for every disk. This is broken because the semantics differ from those
used when starting the VM initially. In the latter case, each SCSI
controller is filled before a new one is added.

If the user specifies an high drive index (sdazz) then at initial
startup, many intermediate SCSI controllers may be added with no
drives.

This patch changes SCSI hotplug so that it exactly matches the
behaviour of initial startup. First the SCSI controller number is
determined for the drive to be hotplugged. If any controller upto
and including that controller number is not yet present, it is
attached. Then finally the drive is attached to the last controller.

NB, this breaks SCSI hotunplug, because there is no 'drive_del'
command in current QEMU. Previous SCSI hotunplug was broken in
any case because it was unplugging the entire controller, not
just the drive in question.

A future QEMU will allow proper SCSI hotunplug of a drive.

This patch is derived from work done by Wolfgang Mauerer on disk
controllers.

* src/qemu/qemu_driver.c: Fix SCSI hotplug to add a drive to
 the correct controller, instead of just attaching a new
  controller.
* src/qemu/qemu_monitor.c, src/qemu/qemu_monitor.h,
  src/qemu/qemu_monitor_json.c, src/qemu/qemu_monitor_json.h,
  src/qemu/qemu_monitor_text.c, src/qemu/qemu_monitor_text.h: Add
  support for 'drive_add' command

This patch allows for explicit hotplug/unplug of SCSI controllers.
Ordinarily this is not required, since QEMU/libvirt will attach
a new SCSI controller whenever one is required. Allowing explicit
hotplug of controllers though, enables the caller to specify a
static PCI address, instead of auto-assigning the next available
PCI slot. Or it will when we have static PCI addressing.

This patch is derived from Wolfgang Mauerer's disk controller
patch series.

* src/qemu/qemu_driver.c: Support hotplug & unplug of SCSI
  controllers
* src/qemu/qemu_monitor.c, src/qemu/qemu_monitor.h,
  src/qemu/qemu_monitor_json.c, src/qemu/qemu_monitor_json.h,
  src/qemu/qemu_monitor_text.c, src/qemu/qemu_monitor_text.h: Add
  new API for attaching PCI SCSI controllers

* src/qemu/qemu_monitor_json.c: We fill in the PCI function number
   now, so remove obsolete XXX comment

Convert the QEMU monitor APIs over to use virDomainDeviceAddress
structs for passing addresses in/out, instead of individual bits.
This makes the number of parameters smaller & easier to deal with.
No functional change

* src/qemu/qemu_driver.c, src/qemu/qemu_monitor.c,
  src/qemu/qemu_monitor.h, src/qemu/qemu_monitor_text.c,
  src/qemu/qemu_monitor_text.h: Change monitor hotplug APIs to
  take an explicit address ptr for all host/guest addresses

* src/qemu/qemu_monitor_json.c: Hook up reset, shutdown,
  poweroff and stop events

Initial support for the new QEMU monitor protocol  using JSON
as the data encoding format instead of plain text

* po/POTFILES.in: Add src/qemu/qemu_monitor_json.c
* src/qemu/qemu_conf.c, src/qemu/qemu_conf.h: Hack to turn on QMP
  mode. Replace with a version number check on >= 0.12 later
* src/qemu/qemu_monitor.c: Delegate to json monitor if enabled
* src/qemu/qemu_monitor_json.c, src/qemu/qemu_monitor_json.h: Add
  impl of QMP protocol
* src/Makefile.am: Add src/qemu/qemu_monitor_json.{c,h}