Re: [PATCH V7 00/12] fix migration of suspended runstate

[Steven Sistare <steven.sistare@oracle.com>]

FYI, these patches still need RB:
  migration: propagate suspended runstate
  tests/qtest: precopy migration with suspend
  tests/qtest: postcopy migration with suspend

This has RB, but the interaction between vm_start and vm_prepare_start
changed, so needs another look.
    cpus: stop vm in suspended runstate

- Steve

On 12/6/2023 12:23 PM, Steve Sistare wrote:
> Migration of a guest in the suspended runstate is broken.  The incoming
> migration code automatically tries to wake the guest, which is wrong;
> the guest should end migration in the same runstate it started.  Further,
> after saving a snapshot in the suspended state and loading it, the vm_start
> fails.  The runstate is RUNNING, but the guest is not.
> 
> See the commit messages for the details.
> 
> Changes in V2:
>   * simplify "start on wakeup request"
>   * fix postcopy, snapshot, and background migration
>   * refactor fixes for each type of migration
>   * explicitly handled suspended events and runstate in tests
>   * add test for postcopy and background migration
> 
> Changes in V3:
>   * rebase to tip
>   * fix hang in new function migrate_wait_for_dirty_mem
> 
> Changes in V4:
>   * rebase to tip
>   * add patch for vm_prepare_start (thanks Peter)
>   * add patch to preserve cpu ticks
> 
> Changes in V5:
>   * rebase to tip
>   * added patches to completely stop vm in suspended state:
>       cpus: refactor vm_stop
>       cpus: stop vm in suspended state
>   * added patch to partially resume vm in suspended state:
>       cpus: start vm in suspended state
>   * modified "preserve suspended ..." patches to use the above.
>   * deleted patch "preserve cpu ticks if suspended".  stop ticks in
>     vm_stop_force_state instead.
>   * deleted patch "add runstate function".  defined new helper function
>     migrate_new_runstate in "preserve suspended runstate"
>   * Added some RB's, but removed other RB's because the patches changed.
> 
> Changes in V6:
>   * all vm_stop calls completely stop the suspended state
>   * refactored and updated the "cpus" patches
>   * simplified the "preserve suspended" patches
>   * added patch "bootfile per vm"
> 
> Changes in V7:
>   * rebase to tip, add RB-s
>   * fix backwards compatibility for global_state.vm_was_suspended
>   * delete vm_prepare_start state argument, and rename patch
>     "pass runstate to vm_prepare_start" to
>     "check running not RUN_STATE_RUNNING"
>   * drop patches:
>       tests/qtest: bootfile per vm
>       tests/qtest: background migration with suspend
>   * rename runstate_is_started to runstate_is_live
>   * move wait_for_suspend in tests
> 
> Steve Sistare (12):
>   cpus: vm_was_suspended
>   cpus: stop vm in suspended runstate
>   cpus: check running not RUN_STATE_RUNNING
>   cpus: vm_resume
>   migration: propagate suspended runstate
>   migration: preserve suspended runstate
>   migration: preserve suspended for snapshot
>   migration: preserve suspended for bg_migration
>   tests/qtest: migration events
>   tests/qtest: option to suspend during migration
>   tests/qtest: precopy migration with suspend
>   tests/qtest: postcopy migration with suspend
> 
>  backends/tpm/tpm_emulator.c          |   2 +-
>  hw/usb/hcd-ehci.c                    |   2 +-
>  hw/usb/redirect.c                    |   2 +-
>  hw/xen/xen-hvm-common.c              |   2 +-
>  include/migration/snapshot.h         |   7 ++
>  include/sysemu/runstate.h            |  16 ++++
>  migration/global_state.c             |  35 ++++++-
>  migration/migration-hmp-cmds.c       |   8 +-
>  migration/migration.c                |  15 +--
>  migration/savevm.c                   |  23 +++--
>  qapi/misc.json                       |  10 +-
>  system/cpus.c                        |  47 +++++++--
>  system/runstate.c                    |   9 ++
>  system/vl.c                          |   2 +
>  tests/migration/i386/Makefile        |   5 +-
>  tests/migration/i386/a-b-bootblock.S |  50 +++++++++-
>  tests/migration/i386/a-b-bootblock.h |  26 +++--
>  tests/qtest/migration-helpers.c      |  27 ++----
>  tests/qtest/migration-helpers.h      |  11 ++-
>  tests/qtest/migration-test.c         | 181 +++++++++++++++++++++++++----------
>  20 files changed, 354 insertions(+), 126 deletions(-)
>