From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-arm-kernel-bounces+bjorn=helgaas.com@lists.infradead.org>
Return-Path: <linux-arm-kernel-bounces+bjorn=helgaas.com@lists.infradead.org>
Date: Fri, 18 Aug 2017 08:12:51 -0600
From: Alex Williamson <alex.williamson@redhat.com>
To: Jan Glauber <jan.glauber@caviumnetworks.com>
Subject: Re: [PATCH v2 3/3] vfio/pci: Don't probe devices that can't be reset
Message-ID: <20170818081251.2bbffe56@w520.home>
In-Reply-To: <20170818134231.GA3464@hc>
References: <1502957663-5527-1-git-send-email-jglauber@cavium.com>
 <1502957663-5527-4-git-send-email-jglauber@cavium.com>
 <20170817070017.1e9c9456@w520.home> <20170818134231.GA3464@hc>
MIME-Version: 1.0
List-Unsubscribe: <http://lists.infradead.org/mailman/options/linux-arm-kernel>,
 <mailto:linux-arm-kernel-request@lists.infradead.org?subject=unsubscribe>
List-Archive: <http://lists.infradead.org/pipermail/linux-arm-kernel/>
List-Post: <mailto:linux-arm-kernel@lists.infradead.org>
List-Help: <mailto:linux-arm-kernel-request@lists.infradead.org?subject=help>
List-Subscribe: <http://lists.infradead.org/mailman/listinfo/linux-arm-kernel>,
 <mailto:linux-arm-kernel-request@lists.infradead.org?subject=subscribe>
Cc: kvm@vger.kernel.org, david.daney@cavium.com, linux-pci@vger.kernel.org,
 linux-kernel@vger.kernel.org, Robert Richter <robert.richter@cavium.com>,
 Jon Masters <jcm@redhat.com>, Bjorn Helgaas <bhelgaas@google.com>,
 linux-arm-kernel@lists.infradead.org
Content-Type: text/plain; charset="us-ascii"
Sender: "linux-arm-kernel" <linux-arm-kernel-bounces@lists.infradead.org>
Errors-To: linux-arm-kernel-bounces+bjorn=helgaas.com@lists.infradead.org
List-ID: <linux-pci.vger.kernel.org>

On Fri, 18 Aug 2017 15:42:31 +0200
Jan Glauber <jan.glauber@caviumnetworks.com> wrote:

> On Thu, Aug 17, 2017 at 07:00:17AM -0600, Alex Williamson wrote:
> > On Thu, 17 Aug 2017 10:14:23 +0200
> > Jan Glauber <jglauber@cavium.com> wrote:
> >   
> > > If a PCI device supports neither function-level reset, nor slot
> > > or bus reset then refuse to probe it. A line is printed to inform
> > > the user.  
> > 
> > But that's not what this does, this requires that the device is on a
> > reset-able bus.  This is a massive regression.  With this we could no
> > longer assign devices on the root complex or any device which doesn't
> > return from bus reset and currently makes use of the NO_BUS_RESET flag
> > and works happily otherwise.  Full NAK.  Thanks,  
> 
> Looks like I missed the slot reset check. So how about this:
> 
> if (pci_probe_reset_slot(pdev->slot) && pci_probe_reset_bus(pdev->bus)) {
> 	dev_warn(...);
> 	return -ENODEV;
> }
> 
> Or am I still missing something here?

We don't require that a device is on a reset-able bus/slot, so any
attempt to impose that requirement means that there are devices that
might work perfectly fine that are now excluded from assignment.  The
entire premise is unacceptable.  Thanks,

Alex

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel