[PATCH 00/17] migration: Add new migration channel connect and TLS upgrade APIs

[Avihai Horon]

Hello,

Today there are several types of migration channels that can be used
during migration: main migration channel, multifd channels and postcopy
preempt channel. Each channel type has its own code to connect and to
TLS upgrade itself when needed. There is no unified API for these tasks
and it makes the code a bit unclear and cumbersome.

This series aims to solve this by introducing two new APIs for the above
tasks that will replace the existing code.

The first one is an API to TLS upgrade migration channels. A new
function, migration_tls_channel_connect(), is introduced and is used by
main migration, multifd and postcopy preempt channels.

The second one is an API to connect migration channels. A new function,
migration_channel_connect(), is introduced and is used by all migration
channels other than main migration channel, i.e., multifd and postcopy
preempt channels. The reason it's not used by main migration channel is
because the main channel is a bit special and has different flows, and I
didn't see a smooth way to include it.

Patch breakdown:
1-5: Some fixes and cleanups.
6-12: Add new migration channel TLS upgrade API.
13-17: Add new migration channel connect API.

Thanks for reviewing.

Avihai Horon (17):
  migration: Fix logic of channels and transport compatibility check
  migration: Move local_err check in migration_ioc_process_incoming()
  migration: Rename default_channel to main_channel
  migration/multifd: Set p->running = true in the right place
  migration/multifd: Wait for multifd channels creation before
    proceeding
  migration/tls: Rename main migration channel TLS functions
  migration/tls: Add new migration channel TLS upgrade API
  migration: Use the new TLS upgrade API for main channel
  migration/multifd: Use the new TLS upgrade API for multifd channels
  migration/postcopy: Use the new TLS upgrade API for preempt channel
  migration/tls: Make migration_tls_client_create() static
  migration/multifd: Consolidate TLS/non-TLS multifd channel error flow
  migration: Store MigrationAddress in MigrationState
  migration: Rename migration_channel_connect()
  migration: Add new migration channel connect API
  migration/multifd: Use the new migration channel connect API for
    multifd
  migration/postcopy: Use the new migration channel connect API for
    postcopy preempt

 migration/channel.h      |  30 +++++++--
 migration/migration.h    |   5 ++
 migration/multifd.h      |   3 +
 migration/postcopy-ram.h |   2 +-
 migration/tls.h          |  30 +++++++--
 migration/channel.c      | 106 +++++++++++++++++++++++++----
 migration/exec.c         |   2 +-
 migration/fd.c           |   2 +-
 migration/file.c         |   2 +-
 migration/migration.c    |  47 ++++++++-----
 migration/multifd.c      | 142 +++++++++++----------------------------
 migration/postcopy-ram.c | 111 +++++++++++-------------------
 migration/ram.c          |   7 ++
 migration/socket.c       |   2 +-
 migration/tls.c          |  94 +++++++++++++++++---------
 migration/trace-events   |  16 ++---
 16 files changed, 344 insertions(+), 257 deletions(-)

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2.26.3