Manohar Castelino mcastelino

How to set up vsock/nfs and QEMU

Wed 25 Apr 16:15:47 BST 2018

Setting up the experimental vsock/nfs between a host Linux machine and a KVM/QEMU client is not quite trivial - let's write it down...

Overview

over in kata containers, we use 9pfs to mount host side filesystems into the QEMU/KVM Virtual Machine.

Resources

https://kubernetes.io/docs/tasks/administer-cluster/access-cluster-api/
https://thenewstack.io/taking-kubernetes-api-spin/ <-- This is just in case.

Main Stuff

There are two ways you can talk to the KUBE API.

Kube-proxy

Start a kube proxy server which will act as a reverse proxy for the client.

Containerd runtimes

A runtime in containerd does not stand at the runc level, but at the platform one. There are separate Linux and Windows runtimes, and they register as plugins:

const (
	runtimeName    = "linux"
	configFilename = "config.json"

virtio is a kernel virtual bus. From drivers/virtio/virtio.c:

static struct bus_type virtio_bus = {
	.name  = "virtio",
	.match = virtio_dev_match,
	.dev_groups = virtio_dev_groups,
	.uevent = virtio_uevent,
	.probe = virtio_dev_probe,
	.remove = virtio_dev_remove,

Hot plugging devices using ACPI, SHPC and native

This gist is to show different ways to hot plug devices in a Virtual Machine

Set up the environment

Create a device mapper

dd if=/dev/zero of=devmap.img count=1 bs=50M

Install

# Tested on Ubuntu 16.04
# Install hyperd, hyperctl, Hyper's kernel and guest image, and their QEMU binary
wget https://hypercontainer-download.s3-us-west-1.amazonaws.com/qemu-hyper/qemu-hyper_2.4.1-1_amd64.deb 
wget https://hypercontainer-download.s3-us-west-1.amazonaws.com/0.8/ubuntu/hypercontainer_0.8.1-1_amd64.deb                   
wget https://hypercontainer-download.s3-us-west-1.amazonaws.com/0.8/ubuntu/hyperstart_0.8.1-1_amd64.deb 

dpkg -i qemu-hyper_2.4.1-1_amd64.deb

Get go 1.8.3:

wget https://storage.googleapis.com/golang/go1.8.3.linux-amd64.tar.gz
sudo tar -xvf go1.8.3.linux-amd64.tar.gz -C /usr/local/
mkdir -p $HOME/go/src
export GOPATH=$HOME/go
export PATH=$PATH:/usr/local/go/bin:$GOPATH/bin
go version

	# Clear Linux install configuration
	#
	# /dev/sda1 /
	# /dev/sda2 /boot
	# /dev/sda3 (reserved partition for devicemapper)
	#

	DEVICE="/dev/sda3"

	echo "Stopping docker"

	Hotplugging cpu:

	Start QEMU with QMP socket available and with startup amount of CPUs less than maxcpus:
	./qemu-system-x86_64 -qmp unix:/tmp/qmp-sock,server,nowait -smp 2,maxcpus=8

	Connect to qmp socket and add cpu:
	socat /tmp/qmp-sock -
	{ "execute": "cpu-add", "arguments": { "id": 2 } }

	Hotpluggable Cpu's can be queried as:

	*.img
	*.raw