Re: [PATCH 3/4] VFIO: pci: amend vfio-pci for explicit binding viasysfs only

From: Scott Wood
Date: Mon Oct 28 2013 - 14:11:23 EST

On Mon, 2013-10-28 at 13:00 -0500, Scott Wood wrote:
> On Mon, 2013-10-28 at 11:47 -0600, Alex Williamson wrote:
> > On Fri, 2013-10-11 at 01:27 -0500, Kim Phillips wrote:
> > > Force the vfio-pci driver to only be bound explicitly via sysfs to avoid
> > > conflics with other drivers in the event of a hotplug.
> >
> > We can't break userspace, so we can't disable the current method of
> > binding devices to vfio-pci. We can add a new method and perhaps
> > deprecate the existing mechanism to be removed at some point in the
> > future. Thanks,
> I thought the existing method involved using sysfs bind, and this was
> just eliminating a race. How does the bind get triggered currently?

OK, so it seems it's relying on the write to new_id calling
driver_attach(). Sigh. I guess we could make driver-sysfs-bind-only be
settable via sysfs, and have new-userspace set both that and PCI_ANY_ID
(or the specific ID if userspace prefers) via new_id. The platform bus
patches could continue as is, since there's no existing mechanism to


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