[PATCH 02/15] hyperv: Add a function to detect hv_device

[Greg KH]

On Fri, Dec 02, 2016 at 07:14:03AM +0000, KY Srinivasan wrote:
> > In other words, why do you need this and PCI or USB doesn't?  Why is
> > hyperv "special"?
> 
> On Hyper-V, each VF interface (SR-IOV interface)
> is paired with an instance of the 
> synthetic interface that is managed by netvsc.
> When the VF interface comes up, we
> need to associate the VF instance with 
> the corresponding netvsc instance. To do this
> without modifying the VF drivers, netvsc registers 
> for netdev events.

Why not modify the VF drivers?  You have the full source to them...