> However, I got booting error like "/dev/vda1 doest exist...", so boot
> failure. How can I fix this?

make sure that your command line on the host looks like that:
kvm -drive file=<your-image>,if=virtio,boot=on <other stuff here>

And check that the guest has the following kernel option enabled:
CONFIG_VIRTIO_BLK

regards,
Felix