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Date: Tue, 29 Oct 2013 04:31:59 +0000 From: Bhushan Bharat-R65777 <R65777@...escale.com> To: Wood Scott-B07421 <B07421@...escale.com> CC: Alex Williamson <alex.williamson@...hat.com>, Kim Phillips <kim.phillips@...aro.org>, Yoder Stuart-B08248 <B08248@...escale.com>, "christoffer.dall@...aro.org" <christoffer.dall@...aro.org>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, "a.motakis@...tualopensystems.com" <a.motakis@...tualopensystems.com>, "agraf@...e.de" <agraf@...e.de>, Sethi Varun-B16395 <B16395@...escale.com>, "peter.maydell@...aro.org" <peter.maydell@...aro.org>, "santosh.shukla@...aro.org" <santosh.shukla@...aro.org>, "kvm@...r.kernel.org" <kvm@...r.kernel.org>, "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org> Subject: RE: [PATCH 3/4] VFIO: pci: amend vfio-pci for explicit binding via sysfs only > -----Original Message----- > From: Wood Scott-B07421 > Sent: Tuesday, October 29, 2013 10:00 AM > To: Bhushan Bharat-R65777 > Cc: Wood Scott-B07421; Alex Williamson; Kim Phillips; Yoder Stuart-B08248; > christoffer.dall@...aro.org; linux-kernel@...r.kernel.org; > a.motakis@...tualopensystems.com; agraf@...e.de; Sethi Varun-B16395; > peter.maydell@...aro.org; santosh.shukla@...aro.org; kvm@...r.kernel.org; > gregkh@...uxfoundation.org > Subject: Re: [PATCH 3/4] VFIO: pci: amend vfio-pci for explicit binding via > sysfs only > > On Mon, 2013-10-28 at 22:52 -0500, Bhushan Bharat-R65777 wrote: > > > > > -----Original Message----- > > > From: Wood Scott-B07421 > > > Sent: Tuesday, October 29, 2013 9:11 AM > > > To: Bhushan Bharat-R65777 > > > Cc: Wood Scott-B07421; Alex Williamson; Kim Phillips; Yoder > > > Stuart-B08248; christoffer.dall@...aro.org; > > > linux-kernel@...r.kernel.org; a.motakis@...tualopensystems.com; > > > agraf@...e.de; Sethi Varun-B16395; peter.maydell@...aro.org; > > > santosh.shukla@...aro.org; kvm@...r.kernel.org; > > > gregkh@...uxfoundation.org > > > Subject: Re: [PATCH 3/4] VFIO: pci: amend vfio-pci for explicit > > > binding via sysfs only > > > > > > 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@...aro.org; > > > > > linux-kernel@...r.kernel.org; a.motakis@...tualopensystems.com; > > > > > agraf@...e.de; Sethi Varun-B16395; peter.maydell@...aro.org; > > > > > santosh.shukla@...aro.org; kvm@...r.kernel.org; > > > > > gregkh@...uxfoundation.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. > > > > store_new_id() function id defined as: > > > > static ssize_t store_new_id(struct device_driver *driver, const char > > *buf, size_t count) { > > struct pci_driver *pdrv = to_pci_driver(driver); > > const struct pci_device_id *ids = pdrv->id_table; > > > > <snip> > > /* Only accept driver_data values that match an existing id_table > > entry */ > > if (ids) { > > retval = -EINVAL; > > while (ids->vendor || ids->subvendor || ids->class_mask) { > > if (driver_data == ids->driver_data) { > > retval = 0; > > break; > > } > > ids++; > > } > > if (retval) /* No match */ > > return retval; > > } > > > > retval = pci_add_dynid(pdrv, vendor, device, subvendor, subdevice, > > class, class_mask, driver_data); <snip> > > > > > > So when ids == NULL it does not check of vendor etc and calls pci_add_dynid() > which in turn calls driver_attach(). > > > > If we change the above loop to break if ids->vendor == PCI_ANY_ID && ids- > >subvendor == PCI_ANY_ID then also we will call pci_add_dyids(). > > What problem are you trying to solve? new_id interface to continue working as before. -Bharat > > -Scott >
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