What are the security risks of running QEMU/KVM as root?

[Maxime Guerreiro]

Hello,

I'd be interested to learn more about the security 'vision' of qemu/kvm being
two components, one running in-kernel, one running in user land. What are the
security advantages of running guests as non-root?

In case of a qemu or KVM vulnerability, won't malicious guests gain kernel
privilege no matter what user is running qemu?

If a guest is able to execute arbitrary code as the "qemu" user, can
it escalate to
root privileges using /dev/kvm?

I've also asked this on StackExchange [1], for visibility.

Thanks,
Maxime

[1]: 
https://security.stackexchange.com/questions/236681/what-are-the-security-risks-of-running-qemu-kvm-as-root