[v2,0/6] migration: Modified 'migrate' QAPI command for migration

Message

Het Gala Feb. 8, 2023, 9:35 a.m. UTC

This is v2 patchset for modified 'migrate' QAPI design for migration
connection.

Links to previous versions:
v1: https://lists.gnu.org/archive/html/qemu-devel/2022-12/msg04339.html

Thanks to Daniel, Markus and Dr. David for their valuable insights.

v1->v2 changelog:
- major improvements in restructuring wire protocol for exec and rdma transport
  backends.
- rdma argument change from [str --> InetSocketAddress]
- exec arguemnt change from [str --> list of string]
- functions are reshuffled into new files as per the recent migration changes
  in qemu.

Abstract:
---------

Current QAPI 'migrate' command design (for initiating a migration
stream) contains information regarding different migrate transport mechanism
(tcp / unix / exec), dest-host IP address, and binding port number in form of
a string. Thus the design does seem to have some design issues. Some of the
issues, stated below are:

1. Use of string URIs is a data encoding scheme within a data encoding scheme.
   QEMU code should directly be able to work with the results from QAPI,
   without resorting to do a second level of parsing (eg. socket_parse()).
2. For features / parameters related to migration, the migration tunables needs
   to be defined and updated upfront. For example, 'migrate-set-capability'
   and 'migrate-set-parameter' is required to enable multifd capability and
   multifd-number of channels respectively. Instead, 'Multifd-channels' can
   directly be represented as a single additional parameter to 'migrate'
   QAPI. 'migrate-set-capability' and 'migrate-set-parameter' commands could
   be used for runtime tunables that need setting after migration has already
   started.

The current patchset focuses on solving the first problem of multi-level
encoding of URIs. The patch defines 'migrate' command as a QAPI discriminated
union for the various transport backends (like socket, exec and rdma), and on
basis of transport backends, different migration parameters are defined.

(uri) string -->  (channel) Channel-type
                            Transport-type
                            Migration parameters based on transport type

-----------------------------------------------------------------------------

Het Gala (6):
  migration: moved hmp_split_at_commma() helper func to qapi-util.c file
  migration: Updated QAPI format for 'migrate' qemu monitor command
  migration: HMP side changes for modified 'migrate' QAPI design
  migration: Avoid multiple parsing of uri in migration code flow
  migration: Modified 'migrate-incoming' QAPI and HMP side changes on
    the destination interface.
  migration: Established connection for listener sockets on the dest
    interface

 include/monitor/hmp.h          |   1 -
 include/qapi/util.h            |   1 +
 migration/exec.c               |  38 ++++++--
 migration/exec.h               |   6 +-
 migration/migration-hmp-cmds.c | 113 +++++++++++++++++++++++-
 migration/migration.c          | 144 +++++++++++++++++++++++--------
 migration/rdma.c               |  39 +++------
 migration/rdma.h               |   5 +-
 migration/socket.c             |  37 ++------
 migration/socket.h             |   5 +-
 monitor/hmp-cmds.c             |  19 ----
 net/net-hmp-cmds.c             |   2 +-
 qapi/migration.json            | 153 ++++++++++++++++++++++++++++++++-
 qapi/qapi-util.c               |  19 ++++
 softmmu/vl.c                   |   2 +-
 stats/stats-hmp-cmds.c         |   2 +-
 16 files changed, 457 insertions(+), 129 deletions(-)