Re: [PATCH] s390/kvm: Reject memory region operations for ucontrol VMs

[Christoph Schlameuss]

On Thu, 27 Jun 2024 14:32:51 +0200
Janosch Frank <frankja@xxxxxxxxxxxxx> wrote:

> On 6/27/24 13:53, Paolo Bonzini wrote:
> > On Mon, Jun 24, 2024 at 11:59 AM Christoph Schlameuss
> > <schlameuss@xxxxxxxxxxxxx> wrote:  
> >>
> >> This change rejects the KVM_SET_USER_MEMORY_REGION and
> >> KVM_SET_USER_MEMORY_REGION2 ioctls when called on a ucontrol VM.
> >> This is neccessary since ucontrol VMs have kvm->arch.gmap set to 0 and
> >> would thus result in a null pointer dereference further in.
> >> Memory management needs to be performed in userspace and using the
> >> ioctls KVM_S390_UCAS_MAP and KVM_S390_UCAS_UNMAP.
> >>
> >> Also improve s390 specific documentation for KVM_SET_USER_MEMORY_REGION
> >> and KVM_SET_USER_MEMORY_REGION2.  
> > 
> > Would be nice to have a selftest for ucontrol VMs, too... just saying :)
> > 
> > Paolo
> >   
> 
> Already in the works, he just hasn't posted it yet :)
> We did do a couple rounds of internal feedback on the tests first.

I do also have a test case for this specifically, but it depends on the
base fixture. So I would send it together with that soon.

Christoph