Current logic assumes that channel connections on the destination side are
always established in the same order as the source and the first one will
always be the main channel followed by the multifid or post-copy
preemption channel. This may not be always true, as even if a channel has a
connection established on the source side it can be in the pending state on
the destination side and a newer connection can be established first.
Basically causing out of order mapping of channels on the destination side.
Currently, all channels except post-copy preempt send a magic number, this
patch uses that magic number to decide the type of channel. This logic is
applicable only for precopy(multifd) live migration, as mentioned, the
post-copy preempt channel does not send any magic number. Also, tls live
migrations already does tls handshake before creating other channels, so
this issue is not possible with tls, hence this logic is avoided for tls
live migrations. This patch uses MSG_PEEK to check the magic number of
channels so that current data/control stream management remains
un-effected.

v2:
  TLS does not support MSG_PEEK, so V1 was broken for tls live
  migrations. For tls live migration, while initializing main channel
  tls handshake is done before we can create other channels, so this
  issue is not possible for tls live migrations. In V2 added a check
  to avoid checking magic number for tls live migration and fallback
  to older method to decide mapping of channels on destination side.

v3:
  1. Split change in two patches, io patch for read_peek routines,
     migration patch for migration related changes.
  2. Add flags to io_readv calls to get extra read flags like
     MSG_PEEK.
  3. Some other minor fixes.

v4:
  1. Removed common *all_eof routines for read peek and added one
     specific to live migration.
  2. Updated to use qemu_co_sleep_ns instead of qio_channel_yield.
  3. Some other minor fixes.

v5:
  1. Handle busy-wait in migration_channel_read_peek due partial reads.

v6:
  With earlier patch, multifd_load_setup was done only in
  migration_incoming_setup but if multifd channel is received before
  default channel, multifd channels will be uninitialized. Moved
  multifd_load_setup to migration_ioc_process_incoming.
  

manish.mishra (2):
  io: Add support for MSG_PEEK for socket channel
  migration: check magic value for deciding the mapping of channels

 chardev/char-socket.c               |  4 +--
 include/io/channel.h                |  6 ++++
 io/channel-buffer.c                 |  1 +
 io/channel-command.c                |  1 +
 io/channel-file.c                   |  1 +
 io/channel-null.c                   |  1 +
 io/channel-socket.c                 | 17 ++++++++-
 io/channel-tls.c                    |  1 +
 io/channel-websock.c                |  1 +
 io/channel.c                        | 16 ++++++---
 migration/channel-block.c           |  1 +
 migration/channel.c                 | 45 ++++++++++++++++++++++++
 migration/channel.h                 |  5 +++
 migration/migration.c               | 54 ++++++++++++++++++++---------
 migration/multifd.c                 | 19 +++++-----
 migration/multifd.h                 |  2 +-
 migration/postcopy-ram.c            |  5 +--
 migration/postcopy-ram.h            |  2 +-
 scsi/qemu-pr-helper.c               |  2 +-
 tests/qtest/tpm-emu.c               |  2 +-
 tests/unit/test-io-channel-socket.c |  1 +
 util/vhost-user-server.c            |  2 +-
 22 files changed, 148 insertions(+), 41 deletions(-)

-- 
2.22.3

Hi Peter, Daniel,

Just a gentle reminder on this patch if it can be merged, and really sorry i see now earlier reminders i sent were on v6[0/2] and somehow you were not CCed on that earlier. You were CCed just on v6[1/2] and v6[2,2] so that's why probably missed it.

Thanks

Manish Mishra

On 21/12/22 12:06 am, manish.mishra wrote:
> Current logic assumes that channel connections on the destination side are
> always established in the same order as the source and the first one will
> always be the main channel followed by the multifid or post-copy
> preemption channel. This may not be always true, as even if a channel has a
> connection established on the source side it can be in the pending state on
> the destination side and a newer connection can be established first.
> Basically causing out of order mapping of channels on the destination side.
> Currently, all channels except post-copy preempt send a magic number, this
> patch uses that magic number to decide the type of channel. This logic is
> applicable only for precopy(multifd) live migration, as mentioned, the
> post-copy preempt channel does not send any magic number. Also, tls live
> migrations already does tls handshake before creating other channels, so
> this issue is not possible with tls, hence this logic is avoided for tls
> live migrations. This patch uses MSG_PEEK to check the magic number of
> channels so that current data/control stream management remains
> un-effected.
>
> v2:
>    TLS does not support MSG_PEEK, so V1 was broken for tls live
>    migrations. For tls live migration, while initializing main channel
>    tls handshake is done before we can create other channels, so this
>    issue is not possible for tls live migrations. In V2 added a check
>    to avoid checking magic number for tls live migration and fallback
>    to older method to decide mapping of channels on destination side.
>
> v3:
>    1. Split change in two patches, io patch for read_peek routines,
>       migration patch for migration related changes.
>    2. Add flags to io_readv calls to get extra read flags like
>       MSG_PEEK.
>    3. Some other minor fixes.
>
> v4:
>    1. Removed common *all_eof routines for read peek and added one
>       specific to live migration.
>    2. Updated to use qemu_co_sleep_ns instead of qio_channel_yield.
>    3. Some other minor fixes.
>
> v5:
>    1. Handle busy-wait in migration_channel_read_peek due partial reads.
>
> v6:
>    With earlier patch, multifd_load_setup was done only in
>    migration_incoming_setup but if multifd channel is received before
>    default channel, multifd channels will be uninitialized. Moved
>    multifd_load_setup to migration_ioc_process_incoming.
>    
>
> manish.mishra (2):
>    io: Add support for MSG_PEEK for socket channel
>    migration: check magic value for deciding the mapping of channels
>
>   chardev/char-socket.c               |  4 +--
>   include/io/channel.h                |  6 ++++
>   io/channel-buffer.c                 |  1 +
>   io/channel-command.c                |  1 +
>   io/channel-file.c                   |  1 +
>   io/channel-null.c                   |  1 +
>   io/channel-socket.c                 | 17 ++++++++-
>   io/channel-tls.c                    |  1 +
>   io/channel-websock.c                |  1 +
>   io/channel.c                        | 16 ++++++---
>   migration/channel-block.c           |  1 +
>   migration/channel.c                 | 45 ++++++++++++++++++++++++
>   migration/channel.h                 |  5 +++
>   migration/migration.c               | 54 ++++++++++++++++++++---------
>   migration/multifd.c                 | 19 +++++-----
>   migration/multifd.h                 |  2 +-
>   migration/postcopy-ram.c            |  5 +--
>   migration/postcopy-ram.h            |  2 +-
>   scsi/qemu-pr-helper.c               |  2 +-
>   tests/qtest/tpm-emu.c               |  2 +-
>   tests/unit/test-io-channel-socket.c |  1 +
>   util/vhost-user-server.c            |  2 +-
>   22 files changed, 148 insertions(+), 41 deletions(-)
>

On Tue, Jan 31, 2023 at 08:29:08PM +0530, manish.mishra wrote:
> Hi Peter, Daniel,
> 
> Just a gentle reminder on this patch if it can be merged, and really
> sorry i see now earlier reminders i sent were on v6[0/2] and somehow you
> were not CCed on that earlier. You were CCed just on v6[1/2] and v6[2,2]
> so that's why probably missed it.

Yes I think so.  For some reason I guess Juan missed this set when sending
the most recent PR. We should pick them up soon.

-- 
Peter Xu

On 31/01/23 8:47 pm, Peter Xu wrote:
> On Tue, Jan 31, 2023 at 08:29:08PM +0530, manish.mishra wrote:
>> Hi Peter, Daniel,
>>
>> Just a gentle reminder on this patch if it can be merged, and really
>> sorry i see now earlier reminders i sent were on v6[0/2] and somehow you
>> were not CCed on that earlier. You were CCed just on v6[1/2] and v6[2,2]
>> so that's why probably missed it.
> Yes I think so.  For some reason I guess Juan missed this set when sending
> the most recent PR. We should pick them up soon.
>

Thanks Peter :)