[PATCH RFC 0/4] Fix issues with zero-length records in migration v2

[Andrew Cooper <andrew.cooper3@citrix.com>]

This series is RFC because it has only had compile testing thusfar.

On AMD hardware supporting Debug Extentions, migration of a PV guest which is
not currently using Debug Extentions fails, as the save side writes a
X86_PV_VCPU_MSRS record with 0 content, which the receving side chokes on.

It was alway the intention that such a record would be omitted, but that
obviously didn't go as intended.

Adjust the docs to clarify that such records should be omitted, but that
receving sides should tolerate their presence.

Andrew Cooper (4):
  docs: Clarify the expected behaviour of zero length records
  tools/libxc: Tolerate zero-length records in migration v2 streams
  tools/libxc: Avoid generating inappropriate zero-length records
  tools/python: Adjust migration v2 library to warn about zero-length
    records

 docs/specs/libxc-migration-stream.pandoc | 16 +++++++++++++++-
 tools/libxc/xc_sr_restore_x86_hvm.c      | 25 ++++++++++++++++++++++---
 tools/libxc/xc_sr_restore_x86_pv.c       | 17 ++++++++++++++---
 tools/libxc/xc_sr_save_x86_hvm.c         |  4 ++++
 tools/libxc/xc_sr_save_x86_pv.c          | 12 ++++++++++++
 tools/python/xen/migration/libxc.py      | 13 ++++++++++++-
 6 files changed, 79 insertions(+), 8 deletions(-)

-- 
2.1.4


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