QEMU

qemu-img create -f qcow2 /Users/rogerleung/ubuntu.qcow2 25G

qemu-system-x86_64 \
    -enable-kvm \
    -no-user-config \
    -nodefaults \
    -show-cursor \
    -M pc-q35-3.1,accel=hvf,usb=off,vmport=off \
    -cpu Penryn,kvm=on,vendor=GenuineIntel \
    -smp 4,sockets=1,cores=2,threads=2 \
    -m 4096 \
    -realtime mlock=off \
    -rtc base=utc,driftfix=slew \
    -drive file=/Users/rogerleung/ubuntu.qcow2,if=none,format=qcow2,id=disk0 \
    -device virtio-blk-pci,bus=pcie.0,addr=0x1,drive=disk0 \
    -netdev user,id=net0 \
    -device virtio-net-pci,netdev=net0,bus=pcie.0,addr=0x2 \
    -device virtio-keyboard-pci,bus=pcie.0,addr=0x3 \
    -device virtio-tablet-pci,bus=pcie.0,addr=0x4 \
    -device virtio-vga,bus=pcie.0,addr=0x5 \
    -cdrom /Users/rogerleung/Downloads/ubuntu-20.04-desktop-amd64.iso -boot d