Hi!

With "[PATCH v6 05/19] net/tap: rework scripts handling" fixed
Reviewed-by: [email protected]

On 9/23/25 13:00, Vladimir Sementsov-Ogievskiy wrote:
Hi all!

Here is a new migration parameter backend-transfer, which allows to
enable local migration of TAP virtio-net backend, including its
properties and open fds.

With this new option, management software doesn't need to
initialize new TAP and do a switch to it. Nothing should be
done around virtio-net in local migration: it just migrates
and continues to use same TAP device. So we avoid extra logic
in management software, extra allocations in kernel (for new TAP),
and corresponding extra delay in migration downtime.

v6:
- rebase on master (to solve conflict with merged
   "io: deal with blocking/non-blocking fds")
- use name "backend-transfer" for the whole feature consistently
   though the whole series. (live-backend is good, but actually,
   we are already in "live-migration", so every its feature may
   have "live-" prefix, and it seems redundant)

03-04: new, making changes in 05 correct
08-09: split "net/tap: rework tap_set_sndbuf()" into two commits
15: fix windows compilation
16: move has_ = true, to _params_init
18: use shorter name

and some other cosmetic changes.

Vladimir Sementsov-Ogievskiy (19):
   net/tap: net_init_tap_one(): drop extra error propagation
   net/tap: net_init_tap_one(): move parameter checking earlier
   net/tap: rework net_tap_init()
   net/tap: pass NULL to net_init_tap_one() in cases when scripts are
     NULL
   net/tap: rework scripts handling
   net/tap: setup exit notifier only when needed
   net/tap: split net_tap_fd_init()
   net/tap: tap_set_sndbuf(): add return value
   net/tap: rework tap_set_sndbuf()
   net/tap: rework sndbuf handling
   net/tap: introduce net_tap_setup()
   net/tap: move vhost fd initialization to net_tap_new()
   net/tap: finalize net_tap_set_fd() logic
   migration: add MIG_EVENT_PRE_INCOMING
   net/tap: postpone tap setup to pre-incoming
   qapi: add interface for backend-transfer virtio-net/tap migration
   virtio-net: support backend-transfer migration for virtio-net/tap
   tests/functional: add skipWithoutSudo() decorator
   tests/functional: add test_x86_64_tap_migration

  hw/net/virtio-net.c                           | 138 +++++-
  include/migration/misc.h                      |   1 +
  include/net/tap.h                             |   5 +
  include/qapi/util.h                           |  17 +
  migration/migration.c                         |   8 +-
  migration/options.c                           |  27 +
  migration/options.h                           |   2 +
  net/tap-bsd.c                                 |   3 +-
  net/tap-linux.c                               |  19 +-
  net/tap-solaris.c                             |   3 +-
  net/tap-stub.c                                |   3 +-
  net/tap-win32.c                               |   5 +
  net/tap.c                                     | 467 ++++++++++++++----
  net/tap_int.h                                 |   4 +-
  qapi/migration.json                           |  47 +-
  tests/functional/qemu_test/decorators.py      |  16 +
  tests/functional/test_x86_64_tap_migration.py | 344 +++++++++++++
  17 files changed, 974 insertions(+), 135 deletions(-)
  create mode 100644 tests/functional/test_x86_64_tap_migration.py



--
Best regards,
Maksim Davydov


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