Date: Thu, 21 Sep 2017 10:06:59 +0200
From: Jan Glauber <jan.glauber@caviumnetworks.com>
To: Alex Williamson <alex.williamson@redhat.com>
Cc: Vadim Lomovtsev <Vadim.Lomovtsev@caviumnetworks.com>,
        Bjorn Helgaas <bhelgaas@google.com>, kvm@vger.kernel.org,
        linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
        Jon Masters <jcm@redhat.com>, linux-arm-kernel@lists.infradead.org,
        david.daney@cavium.com, Robert Richter <robert.richter@cavium.com>
Subject: Re: [v4,0/3] Workaround for bus/slot reset on Cavium cn8xxx root
 ports
Message-ID: <20170921080659.GA12818@hc>
References: <20170908081033.3025-1-jglauber@cavium.com>
 <20170912094049.GA14111@localhost.localdomain>
 <20170920120912.7544420d@t450s.home>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20170920120912.7544420d@t450s.home>
User-Agent: Mutt/1.5.21 (2010-09-15)
SpamDiagnosticOutput: 1:99
SpamDiagnosticMetadata: NSPM
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 21 Sep 2017 08:07:10.5592 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: 711e4ccf-2e9b-4bcf-a551-4094005b6194
X-MS-Exchange-Transport-CrossTenantHeadersStamped: CO2PR07MB2582
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org
Content-Length: 1616
Lines: 47

On Wed, Sep 20, 2017 at 12:09:12PM -0600, Alex Williamson wrote:
> On Tue, 12 Sep 2017 02:40:49 -0700
> Vadim Lomovtsev <Vadim.Lomovtsev@caviumnetworks.com> wrote:
> 
> > Hi all,
> > 
> > Are there any updates on this ?
> > Comments/objections/acks/nacks ?
> > 
> > WBBR,
> > Vadim
> > 
> > On Fri, Sep 08, 2017 at 10:10:30AM +0200, Jan Glauber wrote:
> > > Using vfio-pci on a combination of cn8xxx and some PCI devices results in
> > > a kernel panic. This is triggered by issuing a bus or a slot reset
> > > on the PCI device.
> > > 
> > > With this series both checks indicate that the reset is not possible
> > > preventing the kernel panic.
> > > 
> > > David Daney (2):
> > >   PCI: Allow PCI_DEV_FLAGS_NO_BUS_RESET to be used on bus device
> > >   PCI: Avoid bus reset for Cavium cn8xxx root ports
> > > 
> > > Jan Glauber (1):
> > >   PCI: Avoid slot reset if bus reset is not possible
> > > 
> > >  drivers/pci/pci.c    | 8 ++++++++
> > >  drivers/pci/quirks.c | 8 ++++++++
> > >  2 files changed, 16 insertions(+)  
> 
> 
> Looks ok to me, for series:
> 
> Reviewed-by: Alex Williamson <alex.williamson@redhat.com>

Thanks for the review. And also for being patient with my iterations.

> I am curious why we're happy targeting this quirk at a single device ID
> while at the same time trying to expand the ACS quirk to a notable
> fraction of the Cavium PCI device ID address space.  Thanks,

David, please correct me if I'm wrong but I think this problem only
exists on cn88xx (device id 0xa100) but not on cn81xx/cn83xx (0xa200,
0xa300). I've seen the bridge causing the problem only on cn88xx.

--Jan