linux-kernel - RE: [PATCH 3/4] VFIO: pci: amend vfio-pci for explicit binding via sysfs only

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Message-ID: <6A3DF150A5B70D4F9B66A25E3F7C888D071D50EC@039-SN2MPN1-013.039d.mgd.msft.net>
Date:	Tue, 29 Oct 2013 06:39:45 +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 10:25 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 23:45 -0500, Bhushan Bharat-R65777 wrote:
> >
> > > -----Original Message-----
> > > From: Wood Scott-B07421
> > > Sent: Tuesday, October 29, 2013 10:05 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 23:31 -0500, Bhushan Bharat-R65777 wrote:
> > > >
> > > > > -----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:
> > > > > > 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.
> > >
> > > In what specific way does this allow new_id to continue working as
> > > before?  Be verbose.
> >
> >
> > What I observed that this patch (kim's patch) new_id interface stops working.
> 
> Yes.
> 
> >  This is found to be because store_new_id() checks for pdrv->id_table
> > which is no more NULL, so the below check fails
> 
> I do not think that is the reason.  The reason is because sysfs_bind_only is
> set, and this is not a direct sysfs bind.
> 
> >         if (ids) {
> > ^^
> > This is no more NULL, so enter inside the loop
> >
> >                 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; ^^^^^ This is where it returns
> > as -EINVAL
> 
> Why wouldn't it have broken out of the loop earlier, since driver_data and ids-
> >driver_data should both be zero?  I assume this is with a patch to do
> PCI_ANY_ID in vfio-pci.

hmmm, I am pretty sure I have seen that issue a few time (below is command line output) but now I am not getting any error reported. Although device is not binding to driver because of sysfs_bind_only as you mentioned (I thought of this as a second issue). If I will be able to reproduce the first issue then I will let you guys know otherwise there was no first issue :(

root@...40ds:/sys/bus/pci# echo 0000:01:00.0 > devices/0000\:01\:00.0/driver/unbind
e1000e 0000:01:00.0 eth0: removed PHC
root@...40ds:/sys/bus/pci# echo 8086 10d3 > drivers/vfio-pci/new_id
-sh: echo: write error: Invalid argument
root@...40ds:/sys/bus/pci# echo 0000:01:00.0 > drivers/vfio-pci/bind

-Bharat

> 
> -Scott
>