Subject: Re: kvm PCI assignment & VFIO ramblings

From: Joerg Roedel <[email-masked]>
Date: Tue, 30 Aug 2011 18:13:43 +0200

On Fri, Aug 26, 2011 at 12:04:22PM -0600, Alex Williamson wrote:
> On Thu, 2011-08-25 at 20:05 +0200, Joerg Roedel wrote:

> > If we really expect segment numbers that need the full 16 bit then this
> > would be the way to go. Otherwise I would prefer returning the group-id
> > directly and partition the group-id space for the error values (s32 with
> > negative numbers being errors).
> 
> It's unlikely to have segments using the top bit, but it would be broken
> for an iommu driver to define it's group numbers using pci s:b:d.f if we
> don't have that bit available.  Ben/David, do PEs have an identifier of
> a convenient size?  I'd guess any hardware based identifier is going to
> use a full unsigned bit width.

Okay, if we want to go the secure way I am fine with the "int *group"
parameter. Another option is to just return u64 and use the extended
number space for errors. But that is even worse as an interface, I
think.

	Joerg