Re: [Qemu-devel] [PATCH 0/2 v3] kvm: notify host when guest panicked

[Gleb Natapov]

On Wed, Mar 14, 2012 at 12:29:57PM +0200, Avi Kivity wrote:
> On 03/14/2012 12:26 PM, Wen Congyang wrote:
> > >> If so, is this channel visible to guest userspace? If the channle is 
> > >> visible to guest
> > >> userspace, the program running in userspace may write the same message 
> > >> to the channel.
> > >>
> > > 
> > > Surely there's some kind of access control on channels.
> >
> > The virtio-serial depends on more things than touching the hypervisor. So I 
> > think touching
> > the hypervisor is more reliable than using virtio-serial device, and it is 
> > very simple and
> > easy to use.
> >
> > If we pass something from guest userspace to host, we can use 
> > virtio-serial. But If we pass
> > something from guest kernelspace to host, I still prefer to touch the 
> > hypervisor.
> 
> There's no argument that it's easier.  My concern is different, we're
> adding more and more stuff to the hypervisor because it's easier, which
> bloats it.  Every time we do it we add to compatibility and security
> problems.
> 
> The panic notification is *really* simple, so I don't expect it to cause
> a lot of problems.  But still, if it's possible not to change the
> hypervisor, we must make an effort in that direction.
> 
One more point against using virtio-serial is that it will be likely
compiled as a module which means panic during early boot will not be
reported.

--
                        Gleb.