Re: kvm PCI assignment & VFIO ramblings

Alex Williamson
2011-08-01T16:40:46Z

On Sun, 2011-07-31 at 08:21 +1000, Benjamin Herrenschmidt wrote:
> On Sat, 2011-07-30 at 09:58 +1000, Benjamin Herrenschmidt wrote:
> > Hi folks !
> >
> > So I promised Anthony I would try to summarize some of the comments &
> > issues we have vs. VFIO after we've tried to use it for PCI pass-through
> > on POWER. It's pretty long, there are various items with more or less
> > impact, some of it is easily fixable, some are API issues, and we'll
> > probably want to discuss them separately, but for now here's a brain
> > dump.
> >
> > David, Alexei, please make sure I haven't missed anything :-)
>
> And I think I have :-)
>
> * Config space
>
> VFIO currently handles that as a byte stream. It's quite gross to be
> honest and it's not right. You shouldn't lose access size information
> between guest and host when performing real accesses.
>
> Some config space registers can have side effects and not respecting
> access sizes can be nasty.

It's a bug, let's fix it.

Alex