The RDMA QIOChannel does not support bi-directional communication, so when RDMA 
live migration with postcopy enabled, the source qemu return path get qemu file 
error.

These patches implement bi-directional communication for RDMA QIOChannel and 
disable the RDMA WRITE during the postcopy phase.

This patch just make postcopy works, and will improve performance later.

[v5]
 - rebase
 - fix bug for create a dedicated thread to release rdma resource(David)
 - fix bug for poll the cm event while wait RDMA work request completion(David,Gal)

[v4]
 - not wait RDMA_CM_EVENT_DISCONNECTED event after rdma_disconnect
 - implement io_set_aio_fd_handler function for RDMA QIOChannel (Juan Quintela)
 - invoke qio_channel_yield only when qemu_in_coroutine() (Juan Quintela)
 - create a dedicated thread to release rdma resource
 - poll the cm event while wait RDMA work request completion
 - implement the shutdown function for RDMA QIOChannel

[v3]
 - add a mutex in QEMUFile struct to avoid concurrent channel close (Daniel)
 - destroy the mutex before free QEMUFile (David)
 - use rdmain and rmdaout instead of rdma->return_path (Daniel)

[v2]
 - does not update bytes_xfer when disable RDMA WRITE (David)
 - implement bi-directional communication for RDMA QIOChannel (Daniel)

Lidong Chen (10):
  migration: disable RDMA WRITE after postcopy started
  migration: create a dedicated connection for rdma return path
  migration: avoid concurrent invoke channel_close by different threads
  migration: implement bi-directional RDMA QIOChannel
  migration: Stop rdma yielding during incoming postcopy
  migration: implement io_set_aio_fd_handler function for RDMA
    QIOChannel
  migration: invoke qio_channel_yield only when qemu_in_coroutine()
  migration: create a dedicated thread to release rdma resource
  migration: poll the cm event while wait RDMA work request completion
  migration: implement the shutdown for RDMA QIOChannel

 migration/colo.c              |   2 +
 migration/migration.c         |   4 +
 migration/migration.h         |   7 +
 migration/postcopy-ram.c      |   2 +
 migration/qemu-file-channel.c |  12 +-
 migration/qemu-file.c         |  14 +-
 migration/ram.c               |   4 +
 migration/rdma.c              | 404 ++++++++++++++++++++++++++++++++++++++----
 migration/savevm.c            |   3 +
 9 files changed, 414 insertions(+), 38 deletions(-)

-- 
1.8.3.1