[v8,0/9] migration: Modify 'migrate' and 'migrate-incoming' QAPI commands for migration

Message

Het Gala July 13, 2023, 10:57 a.m. UTC

This is v8 patchset of modified 'migrate' and 'migrate-incoming' QAPI design
for upstream review.

Would like to thank all the maintainers that actively participated in the v7
patchset discussion and gave insightful suggestions to improve the patches.


Link to previous upstream community patchset links:
v1: https://lists.gnu.org/archive/html/qemu-devel/2022-12/msg04339.html
v2: https://lists.gnu.org/archive/html/qemu-devel/2023-02/msg02106.html
v3: https://lists.gnu.org/archive/html/qemu-devel/2023-02/msg02473.html
v4: https://lists.gnu.org/archive/html/qemu-devel/2023-05/msg03064.html
v5: https://lists.gnu.org/archive/html/qemu-devel/2023-05/msg04845.html
v6: https://lists.gnu.org/archive/html/qemu-devel/2023-06/msg01251.html
v7: https://lists.gnu.org/archive/html/qemu-devel/2023-07/msg02027.html

v7 -> v8 changelog:
-------------------
- Formatting, improvemnt around migration qapi documentation and commit
  message descriptions

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 (9):
  migration: New QAPI type 'MigrateAddress'
  migration: convert migration 'uri' into 'MigrateAddress'
  migration: convert socket backend to accept MigrateAddress
  migration: convert rdma backend to accept MigrateAddress
  migration: convert exec backend to accept MigrateAddress.
  migration: New migrate and migrate-incoming argument 'channels'
  migration: modify migration_channels_and_uri_compatible() for new QAPI
    syntax
  migration: Implement MigrateChannelList to migration flow.
  migration: Add test case for modified QAPI syntax

 migration/exec.c               |  72 +++++++++----
 migration/exec.h               |   8 +-
 migration/migration-hmp-cmds.c |  16 ++-
 migration/migration.c          | 182 ++++++++++++++++++++++++++-------
 migration/rdma.c               |  34 +++---
 migration/rdma.h               |   6 +-
 migration/socket.c             |  39 ++-----
 migration/socket.h             |   7 +-
 qapi/migration.json            | 150 ++++++++++++++++++++++++++-
 softmmu/vl.c                   |   2 +-
 tests/qtest/migration-test.c   |  45 ++++++++
 11 files changed, 435 insertions(+), 126 deletions(-)