Re: [Qemu-devel] [PATCH RFC 5/7] s390x/pci: fence off instructions for non-pci

[Cornelia Huck <cohuck@redhat.com>]

On Mon, 10 Jul 2017 14:41:47 +0200
Christian Borntraeger <borntraeger@de.ibm.com> wrote:

> On 07/10/2017 01:04 PM, Cornelia Huck wrote:
> > On Fri, 7 Jul 2017 15:04:52 +0200
> > Cornelia Huck <cohuck@redhat.com> wrote:
> >   
> >> On Fri, 7 Jul 2017 14:55:23 +0200
> >> Christian Borntraeger <borntraeger@de.ibm.com> wrote:
> >>  
> >>> On 07/07/2017 02:21 PM, Cornelia Huck wrote:    
> >>>> If a guest running on a non-pci build issues a pci instruction,
> >>>> throw them an exception.
> >>>>
> >>>> Signed-off-by: Cornelia Huck <cohuck@redhat.com>
> >>>> ---
> >>>>  target/s390x/kvm.c | 24 ++++++++++++++++++++++++
> >>>>  1 file changed, 24 insertions(+)
> >>>>
> >>>> diff --git a/target/s390x/kvm.c b/target/s390x/kvm.c
> >>>> index a3d00196f4..c5c7c27a21 100644
> >>>> --- a/target/s390x/kvm.c
> >>>> +++ b/target/s390x/kvm.c
> >>>> @@ -1160,6 +1160,9 @@ static int kvm_clp_service_call(S390CPU *cpu, struct kvm_run *run)
> >>>>  {
> >>>>      uint8_t r2 = (run->s390_sieic.ipb & 0x000f0000) >> 16;
> >>>>
> >>>> +#ifndef CONFIG_PCI
> >>>> +    return -1;
> >>>> +#endif      
> >>>
> >>> Instead of this ifdefing, can you use the cpu model to decide if the instruction
> >>> should be available? We need to do this anyway for proper handling.
> >>>
> >>> You can then fence off the PCI bits in the CPU model for
> >>> CONFIG_PCI == off.    
> >>
> >> Sounds like a good idea, I'll give it a try.
> >>
> >> We'll probably also want to fence off the sclp facility bit via that
> >> mechanism.  
> > 
> > Slight problem here... we don't have the relevant facilities defined
> > yet, and they are not in the POP (other than "Assigned to IBM internal
> > use").
> > 
> > While I'm pretty sure that the magic number is 69 (judging from the
> > Linux code), I think they should be introduced in a patch by someone
> > who has access to the documentation including the proper names.  
> 
> I will try to get some patches out for PCI in the next days that will contain
> the PCI related facilities.
> 

Cool, thanks!