[PATCH v5 00/15] libxl: Enable save/restore/migration of a restricted QEMU + libxl__ev_qmp_*

[Anthony PERARD <anthony.perard@citrix.com>]

Changes in v5:
    Plenty of patch have been applied.
    Other changes mostly are coding style and other typos.
    Some bug fixes.
    Details can be found in patch notes.

    I have left aside the change to cdrom_insert until I can found what to do
    with the userdata lock.

Changes in v4:
    Better API which meant a lot of other changes.

In order for libxl to be able to manage QEMU while it is restricted, a few
changes are needed. We need a new way to get a startup notification from QEMU
as xenstore may not be accessible when QEMU is ready. We also need to a
different way to have QEMU save it's state and to insert cdrom as a restricted
QEMU doesn't have access to the file system.

For both, we can use QMP, we can use it to query QEMU's status, and we can use
it to send a file descriptor through which QEMU can save its state, or it can
be a cdrom.

We take this opportunity to rewrite the QMP client, and this time been
asynchronous, the result is libxl__ev_qmp_*.

The plat de résistance in this patch series start with patch
"libxl: Design of an async API to issue QMP commands to QEMU"
which implement libxl__ev_qmp_* functions to turn the QMP client into
asynchronous mode.

This comes with changes that uses the new interface.
* "libxl: QEMU startup sync based on QMP"
  which can use QMP to find out when QEMU as started.
  this requires: "libxl_dm: Pre-open QMP socket for QEMU"
  But that only works with dm_restrict=1 as explain in the patch.
* "libxl: Re-implement domain_suspend_device_model using libxl__ev_qmp"
  Which rewrite libxl__qmp_save(), and adds the ability to have QEMU save
  its state to a file descriptor which libxl will have openned.

Patches series available in a git tag:
git fetch https://xenbits.xen.org/git-http/people/aperard/xen-unstable.git libxl-ev-qmp-v5
git checkout -b libxl-ev-qmp-v5 FETCH_HEAD

Cheers,

Anthony PERARD (15):
  libxl: Design of an async API to issue QMP commands to QEMU
  libxl_qmp: Connect to QMP socket
  libxl_qmp: Implement fd callback and read data
  libxl_qmp: Parse JSON input from QMP
  libxl_qmp: Separate QMP message generation from qmp_send_prepare
  libxl_qmp: Prepare the command to be sent
  libxl_qmp: Handle write to QMP socket
  libxl_qmp: Handle messages from QEMU
  libxl_qmp: Respond to QMP greeting
  libxl_exec: Add libxl__spawn_initiate_failure
  libxl_dm: Pre-open QMP socket for QEMU
  libxl: QEMU startup sync based on QMP
  libxl_qmp: Store advertised QEMU version in libxl__ev_qmp
  libxl: Change libxl__domain_suspend_device_model() to be async.
  libxl: Re-implement domain_suspend_device_model using libxl__ev_qmp

 tools/libxl/libxl_create.c           |  30 +-
 tools/libxl/libxl_dm.c               | 130 ++++-
 tools/libxl/libxl_dom_suspend.c      |  22 +-
 tools/libxl/libxl_exec.c             |   7 +
 tools/libxl/libxl_internal.h         | 141 +++++-
 tools/libxl/libxl_qmp.c              | 695 +++++++++++++++++++++++++--
 tools/libxl/libxl_types.idl          |   4 +
 tools/libxl/libxl_types_internal.idl |   8 +
 8 files changed, 950 insertions(+), 87 deletions(-)

-- 
Anthony PERARD


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