[PATCH v2 0/6] Add vmnet.framework based network backend

[Vladislav Yaroshchuk <yaroshchuk2000@gmail.com>]

macOS provides networking API for VMs called vmnet.framework.
I tried to add it as a network backend. All three modes are supported:

-shared:
  allows the guest to comminicate with other guests in shared mode and
  also with external network (Internet) via NAT

-host:
  allows the guest to communicate with other guests in host mode

-bridged:
  bridges the guest with a physical network interface

Separate netdev for each vmnet mode was created because they use quite
different settings, especially since macOS 11.0 when vmnet.framework
gets a lot of updates.

Not sure that I use qemu_mutex_lock_iothread() and
qemu_mutex_unlock_iothread() in correct way while sending packet
from vmnet interface to QEMU. I'll be happy to receive
recomendations how to make this thing better if I done sth wrong.

Also vmnet.framework requires com.apple.vm.networking entitlement to
run without root priveledges. Ad-hoc signing does not fit there,
so I didn't touch anything related to signing. As a result we should
run qemu-system by a priviledged user:
`$ sudo qemu-system-x86_64 -nic vmnet-shared`
otherwise vmnet fails with 'general failure'.

But in any way it seems working now,
I tested it within qemu-system-x86-64 on macOS 10.15.7 host, with nic
models:
- e1000-82545em
- virtio-net-pci

and having such guests:
- macOS 10.15.7
- Ubuntu Bionic (server cloudimg) 

v1: 
 Since v1 minor typos were fixed, patches rebased onto latest master, redudant
 changes removed (small commits squashed)

Vladislav Yaroshchuk (6):
  net/vmnet: dependencies setup, initial preparations
  net/vmnet: create common netdev state structure
  net/vmnet: implement shared mode (vmnet-shared)
  net/vmnet: implement host mode (vmnet-host)
  net/vmnet: implement bridged mode (vmnet-bridged)
  net/vmnet: update qemu-options.hx

 configure           |  31 +++++
 meson.build         |   5 +
 net/clients.h       |  11 ++
 net/meson.build     |   7 ++
 net/net.c           |  10 ++
 net/vmnet-bridged.m | 123 ++++++++++++++++++
 net/vmnet-common.m  | 294 ++++++++++++++++++++++++++++++++++++++++++++
 net/vmnet-host.c    |  93 ++++++++++++++
 net/vmnet-shared.c  |  94 ++++++++++++++
 net/vmnet_int.h     |  48 ++++++++
 qapi/net.json       |  99 ++++++++++++++-
 qemu-options.hx     |  17 +++
 12 files changed, 830 insertions(+), 2 deletions(-)
 create mode 100644 net/vmnet-bridged.m
 create mode 100644 net/vmnet-common.m
 create mode 100644 net/vmnet-host.c
 create mode 100644 net/vmnet-shared.c
 create mode 100644 net/vmnet_int.h

-- 
2.23.0