From mboxrd@z Thu Jan 1 00:00:00 1970 From: Scott Wood Subject: Re: [PATCH 3/4] VFIO: pci: amend vfio-pci for explicit binding via sysfs only Date: Mon, 28 Oct 2013 22:40:42 -0500 Message-ID: <1383018042.3410.69.camel@snotra.buserror.net> References: <1381418830.7979.405.camel@snotra.buserror.net> <1381472840-3470-1-git-send-email-kim.phillips@linaro.org> <1381472840-3470-3-git-send-email-kim.phillips@linaro.org> <1382982462.4097.38.camel@ul30vt.home> <1382983205.3410.6.camel@snotra.buserror.net> <1382983792.3410.13.camel@snotra.buserror.net> <6A3DF150A5B70D4F9B66A25E3F7C888D071D4F0B@039-SN2MPN1-013.039d.mgd.msft.net> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: Wood Scott-B07421 , Alex Williamson , Kim Phillips , Yoder Stuart-B08248 , "christoffer.dall@linaro.org" , "linux-kernel@vger.kernel.org" , "a.motakis@virtualopensystems.com" , "agraf@suse.de" , Sethi Varun-B16395 , "peter.maydell@linaro.org" , "santosh.shukla@linaro.org" , "kvm@vger.kernel.org" , "gregkh@linuxfoundation.org" To: Bhushan Bharat-R65777 Return-path: In-Reply-To: <6A3DF150A5B70D4F9B66A25E3F7C888D071D4F0B@039-SN2MPN1-013.039d.mgd.msft.net> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On Mon, 2013-10-28 at 22:38 -0500, Bhushan Bharat-R65777 wrote: > > > -----Original Message----- > > From: Wood Scott-B07421 > > Sent: Monday, October 28, 2013 11:40 PM > > To: Alex Williamson > > Cc: Kim Phillips; Bhushan Bharat-R65777; Wood Scott-B07421; Yoder Stuart-B08248; > > christoffer.dall@linaro.org; linux-kernel@vger.kernel.org; > > a.motakis@virtualopensystems.com; agraf@suse.de; Sethi Varun-B16395; > > peter.maydell@linaro.org; santosh.shukla@linaro.org; kvm@vger.kernel.org; > > gregkh@linuxfoundation.org > > Subject: Re: [PATCH 3/4] VFIO: pci: amend vfio-pci for explicit binding via > > sysfs only > > > > 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 break. > > What about changing the store_new_id() to bypass exact ids check if driver have PCI_ANY_ID? I don't follow. -Scott