This series enables shadowed CVQ to intercept rx commands related to
VIRTIO_NET_F_CTRL_RX_EXTRA feature through shadowed CVQ, update the virtio
NIC device model so qemu send it in a migration, and the restore of
that rx state in the destination.

To test this patch series, one should modify the `n->parent_obj.guest_features`
value in vhost_vdpa_net_load_rx() using gdb, as the linux virtio-net
driver does not currently support the VIRTIO_NET_F_CTRL_RX_EXTRA
feature.

Note that this patch should be based on
[1] patch "Vhost-vdpa Shadow Virtqueue _F_CTRL_RX commands support"

[1]. https://lore.kernel.org/all/cover.1688743107.git.yin31149@gmail.com/

TestStep
========
1. test the patch series using vp-vdpa device

  - For L0 guest, boot QEMU with virtio-net-pci net device with
`ctrl_vq`, `ctrl_rx` and `ctrl_rx_extra` feature on, something like:
      -device virtio-net-pci,rx_queue_size=256,tx_queue_size=256,
iommu_platform=on,ctrl_vq=on,ctrl_rx=on,ctrl_rx_extra=on...

  - For L1 guest, apply the patch series and compile the code,
start QEMU with vdpa device with svq mode and enable the
`ctrl_vq`, `ctrl_rx` and `ctrl_rx_extra` feature on, something like:
      -netdev type=vhost-vdpa,x-svq=true,...
      -device virtio-net-pci,ctrl_vq=on,ctrl_rx=on,ctrl_rx_extra=on...
Use gdb to attach the VM and break at the net/vhost-vdpa.c:870.

With this series, gdb can hit the breakpoint. Enable the
VIRTIO_NET_F_CTRL_RX_EXTRA feature and enable the non-unicast mode
by entering the following gdb commands:
```gdb
set n->parent_obj.guest_features |= (1 << 20)
set n->nouni = 1
c
```
QEMU should not trigger any errors or warnings.

Without this series, QEMU should fail with
"x-svq=true: vdpa svq does not work with features 0x100000".

ChangeLog
=========
v3:
  - return early if mismatch the condition suggested by Eugenio in
patch 1 "vdpa: Restore packet receive filtering state relative with
_F_CTRL_RX_EXTRA feature"
  - remove the `on` variable suggested by Eugenio in patch 1 "vdpa:
Restore packet receive filtering state relative with
_F_CTRL_RX_EXTRA feature"

v2: https://lore.kernel.org/all/cover.1688365324.git.yin31149@gmail.com/
  - avoid sending CVQ command in default state suggested by Eugenio

v1: https://lists.nongnu.org/archive/html/qemu-devel/2023-06/msg04956.html

Hawkins Jiawei (2):
  vdpa: Restore packet receive filtering state relative with
    _F_CTRL_RX_EXTRA feature
  vdpa: Allow VIRTIO_NET_F_CTRL_RX_EXTRA in SVQ

 net/vhost-vdpa.c | 89 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 89 insertions(+)

-- 
2.25.1