* Peter Xu (peterx@redhat.com) wrote:
> v6:
> - fix page mask to use ramblock psize [Dave]
>
> v5:
> - added one test patch for easier debugging for migration-test
> - added one fix patch [1] for another postcopy race
> - fixed a bug that could trigger when host/guest page size differs
>
> v4:
> - use "void */ulong" instead of "uint64_t" where proper in patch 3/4 [Dave]
>
> v3:
> - fix build on 32bit hosts & rebase
> - remove r-bs for the last 2 patches for Dave due to the changes
>
> v2:
> - add r-bs for Dave
> - add patch "migration: Properly destroy variables on incoming side" as patch 1
> - destroy page_request_mutex in migration_incoming_state_destroy() too [Dave]
> - use WITH_QEMU_LOCK_GUARD in two places where we can [Dave]
>
> We've seen conditional guest hangs on destination VM after postcopy recovered.
> However the hang will resolve itself after a few minutes.
>
> The problem is: after a postcopy recovery, the prioritized postcopy queue on
> the source VM is actually missing. So all the faulted threads before the
> postcopy recovery happened will keep halted until (accidentally) the page got
> copied by the background precopy migration stream.
>
> The solution is to also refresh this information after postcopy recovery. To
> achieve this, we need to maintain a list of faulted addresses on the
> destination node, so that we can resend the list when necessary. This work is
> done via patch 2-5.
>
> With that, the last thing we need to do is to send this extra information to
> source VM after recovered. Very luckily, this synchronization can be
> "emulated" by sending a bunch of page requests (although these pages have been
> sent previously!) to source VM just like when we've got a page fault. Even in
> the 1st version of the postcopy code we'll handle duplicated pages well. So
> this fix does not even need a new capability bit and it'll work smoothly on old
> QEMUs when we migrate from them to the new QEMUs.
>
> Please review, thanks.
Queued
Dave
>
> Peter Xu (6):
> migration: Pass incoming state into qemu_ufd_copy_ioctl()
> migration: Introduce migrate_send_rp_message_req_pages()
> migration: Maintain postcopy faulted addresses
> migration: Sync requested pages after postcopy recovery
> migration/postcopy: Release fd before going into 'postcopy-pause'
> migration-test: Only hide error if !QTEST_LOG
>
> migration/migration.c | 55 ++++++++++++++++++++++++++++++----
> migration/migration.h | 21 ++++++++++++-
> migration/postcopy-ram.c | 25 ++++++++++++----
> migration/savevm.c | 57 ++++++++++++++++++++++++++++++++++++
> migration/trace-events | 3 ++
> tests/qtest/migration-test.c | 6 +++-
> 6 files changed, 154 insertions(+), 13 deletions(-)
>
> --
> 2.26.2
>
>
>
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK