netkit: Support for io_uring zero-copy and AF_XDP

Containers use virtual netdevs to route traffic from a physical netdev
in the host namespace. They do not have access to the physical netdev
in the host and thus can't use memory providers or AF_XDP that require
reconfiguring/restarting queues in the physical netdev.

This patchset adds the concept of queue peering to virtual netdevs that
allow containers to use memory providers and AF_XDP at native speed.
These mapped queues are bound to a real queue in a physical netdev and
act as a proxy.

Memory providers and AF_XDP operations takes an ifindex and queue id,
so containers would pass in an ifindex for a virtual netdev and a queue
id of a mapped queue, which then gets proxied to the underlying real
queue. Peered queues are created and bound to a real queue atomically
through a generic ynl netdev operation.

We have implemented support for this concept in netkit and tested the
latter against Nvidia ConnectX-6 (mlx5) as well as Broadcom BCM957504
(bnxt_en) 100G NICs. For more details see the individual patches.

v1->v2:
 - Removed bind sample ynl code (Stan)
 - Reworked netdev locking to have consistent order (Stan, Kuba)
 - Return 'not supported' in API patch (Stan)
 - Improved ynl documentation (Kuba)
 - Added 'max: s32-max' in ynl spec for ifindex (Kuba)
 - Added also queue type in ynl to have user specify rx to make
   it obvious (Kuba)
 - Use of netdev_hold (Kuba)
 - Avoid static inlines from another header (Kuba)
 - Squashed some commits (Kuba, Stan)
 - Removed ndo_{peer,unpeer}_queues callback and simplified
   code (Kuba)
 - Improved commit messages (Toke, Kuba, Stan, zf)
 - Got rid of locking genl_sk_priv_get (Stan)
 - Removed af_xdp cleanup churn (Maciej)
 - Added netdev locking asserts (Stan)
 - Reject ethtool ioctl path queue resizing (Kuba)
 - Added kdoc for ndo_queue_create (Stan)
 - Uninvert logic in netkit single dev mode (Jordan)
 - Added binding support for multiple queues

Daniel Borkmann (9):
  net, ethtool: Disallow peered real rxqs to be resized
  xsk: Move NETDEV_XDP_ACT_ZC into generic header
  xsk: Move pool registration into single function
  xsk: Add small helper xp_pool_bindable
  xsk: Change xsk_rcv_check to check netdev/queue_id from pool
  xsk: Proxy pool management for mapped queues
  netkit: Add single device mode for netkit
  netkit: Document fast vs slowpath members via macros
  netkit: Add xsk support for af_xdp applications

David Wei (6):
  net: Add bind-queue operation
  net: Implement netdev_nl_bind_queue_doit
  net: Add peer info to queue-get response
  net: Proxy net_mp_{open,close}_rxq for mapped queues
  netkit: Implement rtnl_link_ops->alloc and ndo_queue_create
  netkit: Add io_uring zero-copy support for TCP

 Documentation/netlink/specs/netdev.yaml |  84 +++++++
 drivers/net/netkit.c                    | 314 ++++++++++++++++++++----
 include/linux/ethtool.h                 |   1 +
 include/net/netdev_queues.h             |   5 +
 include/net/netdev_rx_queue.h           |  39 ++-
 include/net/page_pool/memory_provider.h |   4 +-
 include/net/xdp_sock_drv.h              |   8 +-
 include/uapi/linux/if_link.h            |   6 +
 include/uapi/linux/netdev.h             |  22 ++
 net/core/netdev-genl-gen.c              |  25 ++
 net/core/netdev-genl-gen.h              |   1 +
 net/core/netdev-genl.c                  | 177 ++++++++++++-
 net/core/netdev_rx_queue.c              | 124 ++++++++--
 net/ethtool/channels.c                  |  12 +-
 net/ethtool/common.c                    |  10 +-
 net/ethtool/ioctl.c                     |   4 +-
 net/xdp/xsk.c                           |  44 +++-
 net/xdp/xsk.h                           |   5 +-
 net/xdp/xsk_buff_pool.c                 |  18 +-
 tools/include/uapi/linux/netdev.h       |  22 ++
 20 files changed, 816 insertions(+), 109 deletions(-)

-- 
2.43.0