[PATCH 0/6] vhost-user: Add suspend/resume

[Hanna Czenczek <hreitz@redhat.com>]

Hi,

As discussed on the previous version of the virtio-fs migration series
(https://lists.nongnu.org/archive/html/qemu-devel/2023-04/msg01575.html),
we currently don’t have a good way to have a vhost-user back-end fully
cease all operations, including background operations.  To work around
this, we reset it, which is not an option for stateful devices like
virtio-fs.

Instead, we want the same SUSPEND/RESUME model that vhost-vdpa already
has, so that we can suspend back-ends when we want them to stop doing
anything (i.e. on VM stop), and resume them later (i.e. on VM resume).
This series adds these vhost-user operations to the protocol and
implements them in qemu.  Furthermore, it has vhost-user and vhost-vdpa
do roughly the same thing in their reset paths, as far as possible.
That path will still remain as a fall-back if SUSPEND/RESUME is not
implemented, and, given that qemu’s vhost-vdpa code currently does not
make use of RESUME, it is actually always used for vhost-vdpa (to take
the device out of a suspended state).


Hanna Czenczek (6):
  vhost-user.rst: Add suspend/resume
  vhost-vdpa: Move vhost_vdpa_reset_status() up
  vhost: Do not reset suspended devices on stop
  vhost-user: Implement suspend/resume
  vhost-vdpa: Match vhost-user's status reset
  vhost-user: Have reset_status fall back to reset

 docs/interop/vhost-user.rst    |  35 +++++++++++-
 include/hw/virtio/vhost-vdpa.h |   2 -
 include/hw/virtio/vhost.h      |   8 +++
 hw/virtio/vhost-user.c         | 101 ++++++++++++++++++++++++++++++++-
 hw/virtio/vhost-vdpa.c         |  41 ++++++-------
 hw/virtio/vhost.c              |   8 ++-
 6 files changed, 169 insertions(+), 26 deletions(-)

-- 
2.41.0