Add virtio-net support to Lumper

[sameo]

No description provided.

[Kuruyia]

See this crate for an already existing implementation of virtio in Rust: https://github.com/rust-vmm/vm-virtio
The virtio-bindings crate might be interesting, as it contains a virtio_net module: https://docs.rs/virtio-bindings/

[Kuruyia]

The three big steps for implementing networking support in Lumper:

1. Set up a TAP interface on the host. feat(vmm): add tap device creation #11
   For this, there are two possibilities:

   • Either we let Lumper create the TAP interface itself (see cloud-hypervisor), and in that case we get the IP address of that interface from the CLI args (such as --network-host-ip x.x.x.x/x).
   • Or, we get a TAP interface that was already created for us (see rust-vmm/vmm-reference) from the CLI args (such as --network-tap tapX).

   This should leave us with a file descriptor open to read from/write to the TAP interface.
   Note: can we call the TAP interfaces taplets? Like taplet0, taplet1...

2. Set up the virtio-net device in Lumper. feat(virtio): Adding Virtio-net Support to Cloudlet #22
   Because we don't really need the fancy features such as multi-queues, the control queue... we can directly use the implementation from rust-vmm/vmm-reference (and because it's free, we have support for segmentation and checksum offloads).

   We will be using Virtio over MMIO, so we shall not forget to add the virtio_mmio.device=4K@0x<device_register_address>:<notification_irq> thingy to the kernel cmdline.
   Note: it might be nice, but certainly more work, to explore vhost-net to move the virtio-net data plane outside of Lumper and into the host kernel.

3. Set up the IP address of the interface inside the VM. feat: configure guest iface address + rename vmm cli args #35
   This one doesn't seem too hard, we can seemingly pass the IP configuration of a network interface right from the kernel cmdline. We'll also need to get the guest IP address from the CLI args (such as --network-guest-ip x.x.x.x/x).