Re: [PATCH RFC] KVM: inject #UD if instruction emulation fails while vcpu is in cpl==3

[Gleb Natapov <gleb@redhat.com>]

On Thu, May 06, 2010 at 03:33:12PM +0300, Avi Kivity wrote:
> On 05/06/2010 03:25 PM, Gleb Natapov wrote:
> >
> >>We can expect that from a developer or a user subscribed to kvm@.
> >>But what about some random user running virt-manager?
> >>
> >What virt-manager would do about such error?
> 
> Call up abrt.
> 
The idea is not to let userspace process running in a VM kill the VM.

> >>True.  But the same problem exists with cpl>0 #UD.  It may be a
> >>critical driver in userspace (say, video driver).
> >>
> >>Also need to think consider nested kernels (which are userspace for
> >>this purpose).
> >Ugh, we can check if vcpu is in nested mode.
> 
> And do what?  Inject #UD to the guest?  Or force some vmexit?
> 
Does host emulator will ever run on behalf of nested guest? We have
emulator inside nested guest for this.

> >>How about default to unconditional #UD and report, and pause if
> >>requested (in userspace)?  Usually emulation failures will be 100%
> >>reproducible, so the user can rerun their workload.
> >>
> >Didn't what to involve userspace in this, but it can be done of course.
> 
> Whenever we have to make a decision, we involve userspace.
> 
> -- 
> error compiling committee.c: too many arguments to function

--
			Gleb.