Re: [PATCH 4/4] x86,module: Detect CRn and DRn manipulation

Peter Zijlstra
2020-04-08T08:38:20Z

On Wed, Apr 08, 2020 at 02:22:45AM +0200, Paolo Bonzini wrote:
> On 08/04/20 01:15, Andrew Cooper wrote:
> >> Anyhow, I do not think it is the only use-case which is not covered by your
> >> patches (even considering CRs/DRs alone). For example, there is no kernel
> >> function to turn on CR4.VMXE, which is required to run hypervisors on x86.
> > How about taking this opportunity to see if there is a way to improve on
> > the status quo for co-existing hypervisor modules?
>
> Almost serious question: why? I can understand VMware, but why can't at
> least VirtualBox use KVM on Linux? I am not sure if they are still
> running device emulation in ring zero, but if so do you really want to
> do that these days?

Having had the 'joy' of looking at the virtual-puke^Wbox code recently,
nobody with half a hair of sense on their head will want to ever touch
that thing again.

It's a security nightmare, and that's the best part of it.