Subject: Re: linux next: Native Linux KVM tool inclusion request

From: Avi Kivity <[email-masked]>
Date: Wed, 24 Aug 2011 11:31:30 +0300

On 08/23/2011 08:08 AM, Pekka Enberg wrote:
> As for changes, we've implemented rootfs over 9p with "kvm run"
> booting to host filesystem "/bin/sh" by default.

Isn't this dangerous?  Users expect virtualization to land them in 
sandbox, but here an rm -rf / in the guest will happily junk the host 
filesystem.

> It still needs some
> work and we hope to enable networking too. We also have patches to use
> overlayfs so that the guest is able to use host filesystem in
> copy-on-write manner.
>

Still dangerous (but just to the guest), since it's not a true 
snapshot.  If the host filesystem changes underneath the guest, it will 
see partial and incoherent updates.  Copy-on-write only works if the 
host filesystem doesn't change.

-- 
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.