On Mon, 2023-01-16 at 20:22 +0100, Thomas Gleixner wrote:
> > Tested-by: David Woodhouse <dwmw@amazon.co.uk>
> > 
> > Albeit only under qemu with
> > https://git.infradead.org/users/dwmw2/qemu.git/shortlog/refs/heads/xenfv
> > and not under real Xen.
> 
> Five levels of emulation. What could possibly go wrong?

It's the opposite — this is what happened when I threw my toys out of
the pram and said, "You're NOT doing that with nested virtualization!".

One level of emulation. We host guests that think they're running on
Xen, directly in QEMU/KVM by handling the hypercalls and event
channels, grant tables, etc.

We virtualised Xen itself :)

Now you have no more excuses for breaking Xen guest mode!