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"

Steve Sistare (14):
  cpus: pass runstate to vm_prepare_start
  cpus: vm_was_suspended
  cpus: stop vm in suspended runstate
  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
  tests/qtest: bootfile per vm
  tests/qtest: background migration with suspend

 backends/tpm/tpm_emulator.c          |   2 +-
 gdbstub/system.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            |  19 ++-
 migration/global_state.c             |  10 ++
 migration/migration-hmp-cmds.c       |   8 +-
 migration/migration.c                |  15 +--
 migration/savevm.c                   |  23 ++--
 qapi/misc.json                       |  10 +-
 system/cpus.c                        |  49 +++++--
 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         | 240 +++++++++++++++++++++++++----------
 21 files changed, 382 insertions(+), 139 deletions(-)

-- 
1.8.3.1

Hi Peter and Fabiano,

Any comments on these patches, before I send V7?  They are not affected by
the other changes we have discussed, except for renaming runstate_is_started
to runstate_is_live.

  [PATCH V6 04/14] cpus: vm_resume
  [PATCH V6 06/14] migration: preserve suspended runstate
  [PATCH V6 07/14] migration: preserve suspended for snapshot
  [PATCH V6 08/14] migration: preserve suspended for bg_migration

- Steve

On 11/30/2023 4:37 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"
> 
> Steve Sistare (14):
>   cpus: pass runstate to vm_prepare_start
>   cpus: vm_was_suspended
>   cpus: stop vm in suspended runstate
>   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
>   tests/qtest: bootfile per vm
>   tests/qtest: background migration with suspend
> 
>  backends/tpm/tpm_emulator.c          |   2 +-
>  gdbstub/system.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            |  19 ++-
>  migration/global_state.c             |  10 ++
>  migration/migration-hmp-cmds.c       |   8 +-
>  migration/migration.c                |  15 +--
>  migration/savevm.c                   |  23 ++--
>  qapi/misc.json                       |  10 +-
>  system/cpus.c                        |  49 +++++--
>  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         | 240 +++++++++++++++++++++++++----------
>  21 files changed, 382 insertions(+), 139 deletions(-)
>

On Tue, Dec 05, 2023 at 01:52:23PM -0500, Steven Sistare wrote:
> Hi Peter and Fabiano,
> 
> Any comments on these patches, before I send V7?  They are not affected by
> the other changes we have discussed, except for renaming runstate_is_started
> to runstate_is_live.
> 
>   [PATCH V6 04/14] cpus: vm_resume
>   [PATCH V6 06/14] migration: preserve suspended runstate
>   [PATCH V6 07/14] migration: preserve suspended for snapshot
>   [PATCH V6 08/14] migration: preserve suspended for bg_migration

One nitpick I put in the reply there, all look good to me in general.

Side note: I'll be away for the rest of the week.

Thanks,

-- 
Peter Xu

Steven Sistare <steven.sistare@oracle.com> writes:

> Hi Peter and Fabiano,
>
> Any comments on these patches, before I send V7?  They are not affected by
> the other changes we have discussed, except for renaming runstate_is_started
> to runstate_is_live.
>
>   [PATCH V6 04/14] cpus: vm_resume
>   [PATCH V6 06/14] migration: preserve suspended runstate
>   [PATCH V6 07/14] migration: preserve suspended for snapshot

Nothing catches my eye for now.

>   [PATCH V6 08/14] migration: preserve suspended for bg_migration

This has my r-b already.