Control VQ is the way net devices use to send changes to the device state, like
the number of active queues or its mac address.

QEMU needs to intercept this queue so it can track these changes and is able to
migrate the device. It can do it from 1576dbb5bbc4 ("vdpa: Add x-svq to
NetdevVhostVDPAOptions"). However, to enable x-svq implies to shadow all VirtIO
device's virtqueues, which will damage performance.

This series adds address space isolation, so the device and the guest
communicate directly with them (passthrough) and CVQ communication is split in
two: The guest communicates with QEMU and QEMU forwards the commands to the
device.

This patch add new features so is targeted for qemu 8.0.

Comments are welcome. Thanks!

v8:
- Do not allocate iova_tree on net_init_vhost_vdpa if only CVQ is
  shadowed. Move the iova_tree allocation to
  vhost_vdpa_net_cvq_start and vhost_vdpa_net_cvq_stop in this case.

v7:
- Never ask for number of address spaces, just react if isolation is not
  possible.
- Return ASID ioctl errors instead of masking them as if the device has
  no asid.
- Rename listener_shadow_vq to shadow_data
- Move comment on zero initailization of vhost_vdpa_dma_map above the
  functions.
- Add VHOST_VDPA_GUEST_PA_ASID macro.

v6:
- Do not allocate SVQ resources like file descriptors if SVQ cannot be used.
- Disable shadow CVQ if the device does not support it because of net
  features.

v5:
- Move vring state in vhost_vdpa_get_vring_group instead of using a
  parameter.
- Rename VHOST_VDPA_NET_CVQ_PASSTHROUGH to VHOST_VDPA_NET_DATA_ASID

v4:
- Rebased on last CVQ start series, that allocated CVQ cmd bufs at load
- Squash vhost_vdpa_cvq_group_is_independent.
- Do not check for cvq index on vhost_vdpa_net_prepare, we only have one
  that callback registered in that NetClientInfo.
- Add comment specifying behavior if device does not support _F_ASID
- Update headers to a later Linux commit to not to remove SETUP_RNG_SEED

v3:
- Do not return an error but just print a warning if vdpa device initialization
  returns failure while getting AS num of VQ groups
- Delete extra newline

v2:
- Much as commented on series [1], handle vhost_net backend through
  NetClientInfo callbacks instead of directly.
- Fix not freeing SVQ properly when device does not support CVQ
- Add BIT_ULL missed checking device's backend feature for _F_ASID.

Eugenio Pérez (12):
  vdpa: use v->shadow_vqs_enabled in vhost_vdpa_svqs_start & stop
  vhost: set SVQ device call handler at SVQ start
  vhost: allocate SVQ device file descriptors at device start
  vhost: move iova_tree set to vhost_svq_start
  vdpa: add vhost_vdpa_net_valid_svq_features
  vdpa: extract vhost_vdpa_svq_allocate_iova_tree
  vdpa: move SVQ vring features check to net/
  vdpa: allocate SVQ array unconditionally
  vdpa: add asid parameter to vhost_vdpa_dma_map/unmap
  vdpa: store x-svq parameter in VhostVDPAState
  vdpa: add shadow_data to vhost_vdpa
  vdpa: always start CVQ in SVQ mode if possible

 hw/virtio/vhost-shadow-virtqueue.h |   5 +-
 include/hw/virtio/vhost-vdpa.h     |  16 ++-
 hw/virtio/vhost-shadow-virtqueue.c |  44 ++------
 hw/virtio/vhost-vdpa.c             | 126 ++++++++++-----------
 net/vhost-vdpa.c                   | 172 ++++++++++++++++++++++++-----
 hw/virtio/trace-events             |   4 +-
 6 files changed, 236 insertions(+), 131 deletions(-)

-- 
2.31.1