[RFC v2 00/13] Dinamycally switch to vhost shadow virtqueues at vdpa net migration

[Eugenio Pérez]

It's possible to migrate vdpa net devices if they are shadowed from the
start.  But to always shadow the dataplane is effectively break its host
passthrough, so its not convenient in vDPA scenarios.

This series enables dynamically switching to shadow mode only at
migration time.  This allow full data virtqueues passthrough all the
time qemu is not migrating.

Successfully tested with vdpa_sim_net (but it needs some patches, I
will send them soon) and qemu emulated device with vp_vdpa with
some restrictions:
* No CVQ.
* VIRTIO_RING_F_STATE patches.
* Expose _F_SUSPEND, but ignore it and suspend on ring state fetch like
  DPDK.

Comments are welcome, especially in the patcheswith RFC in the message.

v2:
- Use a migration listener instead of a memory listener to know when
  the migration starts.
- Add stuff not picked with ASID patches, like enable rings after
  driver_ok
- Add rewinding on the migration src, not in dst
- v1 at https://lists.gnu.org/archive/html/qemu-devel/2022-08/msg01664.html

Eugenio Pérez (13):
  vdpa: fix VHOST_BACKEND_F_IOTLB_ASID flag check
  vdpa net: move iova tree creation from init to start
  vdpa: copy cvq shadow_data from data vqs, not from x-svq
  vdpa: rewind at get_base, not set_base
  vdpa net: add migration blocker if cannot migrate cvq
  vhost: delay set_vring_ready after DRIVER_OK
  vdpa: delay set_vring_ready after DRIVER_OK
  vdpa: Negotiate _F_SUSPEND feature
  vdpa: add feature_log parameter to vhost_vdpa
  vdpa net: allow VHOST_F_LOG_ALL
  vdpa: add vdpa net migration state notifier
  vdpa: preemptive kick at enable
  vdpa: Conditionally expose _F_LOG in vhost_net devices

 include/hw/virtio/vhost-backend.h |   4 +
 include/hw/virtio/vhost-vdpa.h    |   1 +
 hw/net/vhost_net.c                |  25 ++-
 hw/virtio/vhost-vdpa.c            |  64 +++++---
 hw/virtio/vhost.c                 |   3 +
 net/vhost-vdpa.c                  | 247 +++++++++++++++++++++++++-----
 6 files changed, 278 insertions(+), 66 deletions(-)

-- 
2.31.1