[PATCH 0/3] xen: Use PM/Hibernate events for save/restore/chkpt

[Shriram Rajagopalan <rshriram@cs.ubc.ca>]

The current implementation of xen guest save/restore/checkpoint functionality
uses PM_SUSPEND and PM_RESUME events. This is not optimal when taking
checkpoints of a virtual machine (where the suspend hypercall returns
non-zero, requiring the devices and xenbus to just pickup from where they left
off instead of a complete teardown/reconnect to backend). 

The following set of patches modify this implementation to use Hibernate style
control flow (freeze/restore for save/restore and freeze/thaw for checkpoint,
which is merely a cancelled save akin to failed swsusp() ).

These patches are against Ian Campbell's PVHVM tree at
git://xenbits.xen.org/people/ianc/linux-2.6.git for-stefano/pvhvm

at commit 8a8d1bc753c4e2dda5f2890292d60c67d6ebb573
kernel version: 2.6.38-rc4

Save/Restore and Checkpoint functionality have been tested on PV and PV-HVM
Guest Domains. Patches have been run through checkpatch.pl.

Changes since last resend(s):
  - xenbus_pm_ops has static const qualifier..
  - The conditional macro CONFIG_HIBERNATION around the freeze/thaw/restore
     cases in pm_op and pm_noirq_op functions in drivers/base/power/main.c has
     been expanded to CONFIG_HIBERNATION || CONFIG_XEN_SAVE_RESTORE.
  - CONFIG_PM_SLEEP in drivers/xen/manage.c has been changed to
    CONFIG_XEN_SAVE_RESTORE


Kazuhiro SUZUKI (1):
  xen: xenbus PM events support

Shriram Rajagopalan (2):
  xen: use freeze/restore/thaw PM events for suspend/resume/chkpt
  PM: pm.h - Add comments about Xen save/restore/chkpt use case

 drivers/base/power/main.c                  |    8 ++++----
 drivers/xen/manage.c                       |   16 ++++++++--------
 drivers/xen/xenbus/xenbus_probe.c          |   12 ++++++++++--
 drivers/xen/xenbus/xenbus_probe.h          |    3 ++-
 drivers/xen/xenbus/xenbus_probe_frontend.c |   11 +++++++++--
 include/linux/pm.h                         |   19 +++++++++++++++++++
 include/xen/xenbus.h                       |    2 +-
 7 files changed, 53 insertions(+), 18 deletions(-)