Re: PV passthrough of sibling igbvf's

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 16/10/12 16:04, Laszlo Ersek wrote:
> A closer pointer into the changeset:
>
> http://xenbits.xensource.com/xen-unstable.hg/rev/5b433b4fca34#l16.85
>
> The patch doesn't seem to justify the grouping specifically, thus I did
> not even try to refute it.
>
> Now that you point it out, match_slot() is probably insufficient grounds
> to group functions together. Maybe we should check *additionally* if the
> device being passed through is multi-function. I'll try it.

While that would hopefully solve the bug you have discovered, it does
raise some more queries.

What should we do when passing through only the first function of a
multifunction device, specifically in reference to domain
disagregation?  I would like to hope things would just work, but I am
somewhat doubtful.

For SRIOV hardware, passing the physical function through should be fine
(even though it is a multifunction device), as it is specifically
designed to work in this way.  For a CNA however, the chances of getting
it working at all with different functions in different domains is
unlikely at best.

I just wanted to put these thoughts out in case anyone has any bright
ideas about how to solve them.

~Andrew

>
> Thanks!
> Laszlo

-- 
Andrew Cooper - Dom0 Kernel Engineer, Citrix XenServer
T: +44 (0)1223 225 900, http://www.citrix.com