kvm-std

#!/bin/sh
set -e

usage() {
  local p=$(basename $0)
  cat <<EOF >&2
$p - Run QEMU/KVM
Usage: $p <rootfs-or-image> <qemu-options...> -- <boot-options...>
Example:
  # $p /n/sid64
  # $p /n/sid64-snap00
  # $p /n/sid64/boot/vmlinuz-4.14.0-3-amd64
  # $p /n/sid64/boot/initrd.img-4.14.0-3-amd64
  # $p /some/image.qcow2
  # $p /n/sid64 -curses -bios OVMF.fd
  # $p /n/sid64 -device vfio-pci,host=00:1a.0
  # $p /n/sid64 -device vfio-pci,host=00:1a.0,x-vga=on -vga none
  # $p /n/sid64 -usb -device usb-host,hostbus=2,hostaddr=3
  # $p none -drive file=/some/image.raw,format=raw
  # $p /n/sid64 -drive file=/dev/sdx,format=raw,if=virtio,cache=none
  # NORUN=echo $p /n/sid64
  # KVM_HDD=hda $p /n/sid64 -drive file=/disk.dd,format=raw,cache=none
  # KVM_MEM=64G $p /n/sid64 -smp cpus=32
  # KVM_IF0=br0 $p /n/sid64 -gdb tcp::1234 -- vsyscall=emulate
  # KVM_IF1=br1 $p /n/sid64 -s -- crashkernel=128M
EOF
  exit 1
}

log() { echo "$@" >&2; }
die() { log "$@"; exit 1; }

makeroot() {
  local want=$1
  local bn=$(basename $want)
  local dn=$(dirname  $want)

  # either just use given path, or clone from skelton
  while [ -n "$bn" ]; do
    local skel="$dn/$bn"

    if [ -d "$skel" ]; then
      if [ "$skel" != "$want" ]; then
        sudo btrfs sub snap "$skel" "$want" > /dev/null
      fi
      return
    fi
    bn=$(echo $bn | sed 's/.$//')
  done

  log "Failed to prepare: $want"
}

findboot() {
  local arg=$1
  local img

  case "$arg" in
  -|none) echo exitok=1; return;;
  esac

  # clone environment on-demand
  test -e "$arg" || makeroot ${arg%%/boot/*}

  # check if arg is a block device or system image (> 100MB)
  if [ -b "$arg" -o $(stat -c %s "$arg") -gt $((1024 * 1024 * 100)) ]; then
    echo boot_type=drive
    echo KVM_HDD=hda
    echo drive=$arg
    echo exitok=1
    return
  fi

  # check if arg is either a kernel or initrd image
  if [ -f "$arg" ]; then
    img="$arg"
  elif [ -d "$arg/boot" ]; then
    img=$(ls -1 -v $arg/boot/vmli* | egrep -v '(old|bak)' | head -1)
  else
    log "Not bootable: $arg"
    return
  fi

  local ver=$(basename $img | cut -d- -f2-)
  local loc=${img%%/boot/*}

  # return whatever found
  echo boot_type=nfs
  echo nfsdir=$loc
  echo initrd=$(find $loc/boot/init*${ver} 2> /dev/null | egrep -v '(old|bak)' | sort -V | head -1)
  echo kernel=$(find $loc/boot/vmli*${ver} 2> /dev/null | egrep -v '(old|bak)' | sort -V | head -1)
  echo exitok=1
}

run() {
  local arg=$1; shift

  # just pass-through other args
  local qemu_opt="$(echo $@ | awk -F-- '{ print $1 }')"
  local boot_opt="$(echo $@ | awk -F-- '{ print $2 }')"

  # setup boot configuration
  local boot_type
  local drive KVM_HDD
  local nfsdir kernel initrd
  local $(findboot $arg)
  test -n "$exitok" || die "Failed to boot: $arg"

  # select boot source
  if [ -n "$kernel" ]; then

    # select arch
    local tty=ttyS0
    case "$kernel" in
    *aarch64*) : ${QEMU:=qemu-system-aarch64};;
     *mipsel*) : ${QEMU:=qemu-system-mipsel};;
     *x86_64*) : ${QEMU:=qemu-system-x86_64 --enable-kvm};;
      *amd64*) : ${QEMU:=qemu-system-x86_64 --enable-kvm};;
       *i386*) : ${QEMU:=qemu-system-i386 --enable-kvm};;
       *mips*) : ${QEMU:=qemu-system-mips};;
        *arm*) : ${QEMU:=qemu-system-arm}; tty=ttyAMA0;;
            *) die "Unknown arch: $kernel"
    esac

    if [ -n "$KVM_HDD" ]; then
      case "$KVM_HDD" in
      vda) append="ip=dhcp root=/dev/vda1 rw panic=30 console=$tty";;
      sda) append="ip=dhcp root=/dev/sda1 rw panic=30 console=$tty";;
      hda) append="ip=dhcp root=/dev/hda1 rw panic=30 console=$tty";;
      *)   append="ip=dhcp root=$KVM_HDD  rw panic=30 console=$tty";;
      esac
    elif [ -n "$nfsdir" ]; then
      append="ip=dhcp root=/dev/nfs rw nfsroot=${KVM_NFS:=10.0.100.10}:$nfsdir,tcp,soft,intr,nolock panic=30 console=$tty"
    fi
  fi

  #
  # NOTE:
  # - snapshot saves to $TMPDIR
  #
  $NORUN sudo TMPDIR=${TMPDIR:=/var/tmp} ${QEMU:=kvm} \
  -nographic -m ${KVM_MEM:=256M} \
  -k ja -echr 0x14 \
  -net nic,model=virtio,macaddr=$(macgen-qemu 0 $PPID) \
  -net bridge,br=${KVM_IF0:=vz-fg} \
  -net nic,model=virtio,macaddr=$(macgen-qemu 1 $PPID) \
  -net bridge,br=${KVM_IF1:=vz-bg} \
  ${drive:+-drive file=$drive,if=virtio,cache=none} \
  ${kernel:+-kernel $kernel} \
  ${initrd:+-initrd $initrd} \
  ${append:+-append "$append $boot_opt"} \
  $qemu_opt
}

test $# -gt 0 || usage
run "$@"