[PATCH 2/2] staging: hv_uio userspace i/o driver for Hyper-V VMbus

[Stephen Hemminger]

On Fri, 14 Oct 2016 19:06:47 +0200
Greg KH <greg at kroah.com> wrote:

> On Fri, Oct 14, 2016 at 09:43:52AM -0700, Stephen Hemminger wrote:
> > From: Stephen Hemminger <sthemmin at microsoft.com>
> > 
> > This is a staging driver to enable userspace networking on VMBus.
> > Hyper-V does not support guest IOMMU, so this is an alternative
> > to allow for applications using DPDK.
> > 
> > This is based on earlier GPL driver developed for DPDK by Brocade.
> > 
> > Signed-off-by: Stephen Hemminger <sthemmin at microsoft.com>
> > ---
> >  drivers/hv/connection.c         |   1 +
> >  drivers/staging/Kconfig         |   2 +
> >  drivers/staging/Makefile        |   1 +
> >  drivers/staging/hv_uio/Kconfig  |   6 ++
> >  drivers/staging/hv_uio/Makefile |   4 +
> >  drivers/staging/hv_uio/hv_uio.c | 222 ++++++++++++++++++++++++++++++++++++++++  
> 
> Why staging?  If you do this, I need a TODO file to list what needs to
> be done to it in order to get it out of staging...

I think this needs to go into staging because not convinced that it is completely
secure.  For example, a malicious userspace driver could certainly break other
VMBus drivers on the system (shared notification areas). Also, the ABI is not
stable; new features are certain to break compatibility.

Longer term, a better solution is to support something like VFIO which provides
a better API. But would have to be like VFIO-noiommu and VFIO is specific to
PCI right now.