Re: [Qemu-devel] [PATCH 0/3] UUID validation during migration

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Yury Kotov (yury-kotov@yandex-team.ru) wrote:
> Hi,
> 
> This series adds an UUID validation at the start of the migration
> on the target side. The idea is to identify the source of migration.
> 
> Possible case of problem:
> 1. There are 3 servers: A, B and C
> 2. Server A has a VM 1, server B has a VM 2
> 3. VM 1 and VM 2 want to migrate to the server C
> 4. Target of VM 1 starts on the server C and dies too quickly for some reason
> 5. Target of VM 2 starts just after that and listen the same tcp port X, which
>    the target of VM 1 wanted to use
> 6. Source of VM 1 connects to the tcp port X, and migrates to VM 2 source

That shouldn't be possible in practice; you specify the destination tcp
port when you start the destination qemu; so unless the management code
that starts the migration is very broken it should know which port it's
migrating to.
However, if it is very broken then this is a good check.

Dave

> 7. It's possible that migration might be successful (e.g., devices are the same)
> 8. So, the target of VM 2 is in undefined state
> 
> The series adds a capability to prevent successful (by mistake) migration.
> 
> The new capability x-validate-uuid only affects the source so that it sends
> its UUID to the target. The target will validate the received UUID and stop
> the migration if UUIDs are not equal.
> 
> Regards,
> Yury
> 
> Yury Kotov (3):
>   migration: Add x-validate-uuid capability
>   tests/libqtest: Allow to set expected exit status
>   tests/migration: Add a test for x-validate-uuid capability
> 
>  migration/migration.c  |   9 +++
>  migration/migration.h  |   1 +
>  migration/savevm.c     |  45 +++++++++++++
>  qapi/migration.json    |   5 +-
>  tests/libqtest.c       |  14 ++++-
>  tests/libqtest.h       |   9 +++
>  tests/migration-test.c | 140 ++++++++++++++++++++++++++++++++---------
>  7 files changed, 189 insertions(+), 34 deletions(-)
> 
> -- 
> 2.22.0
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK