From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751767AbdKHRqW (ORCPT ); Wed, 8 Nov 2017 12:46:22 -0500 Received: from emh04.mail.saunalahti.fi ([62.142.5.110]:58345 "EHLO emh04.mail.saunalahti.fi" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751344AbdKHRqV (ORCPT ); Wed, 8 Nov 2017 12:46:21 -0500 X-Greylist: delayed 490 seconds by postgrey-1.27 at vger.kernel.org; Wed, 08 Nov 2017 12:46:20 EST Date: Wed, 8 Nov 2017 19:38:08 +0200 From: Pasi =?iso-8859-1?Q?K=E4rkk=E4inen?= To: Govinda Tatti Cc: Jan Beulich , Konrad Wilk , Juergen Gross , xen-devel@lists.xenproject.org, Boris Ostrovsky , linux-kernel@vger.kernel.org Subject: Re: [Xen-devel] [PATCH] Xen/pciback: Implement PCI slot or bus reset with 'do_flr' SysFS attribute Message-ID: <20171108173808.GH20756@reaktio.net> References: <20171106174842.20276-1-Govinda.Tatti@Oracle.COM> <5A01D3F3020000780018CE86@prv-mh.provo.novell.com> <8940b38d-715c-9fcb-cc74-46574d416703@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <8940b38d-715c-9fcb-cc74-46574d416703@oracle.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On Wed, Nov 08, 2017 at 09:44:48AM -0600, Govinda Tatti wrote: > Thanks Jan for your review comments. Please see below for my comments. > > On 11/7/2017 8:40 AM, Jan Beulich wrote: > >>>>On 06.11.17 at 18:48, wrote: > >>--- a/Documentation/ABI/testing/sysfs-driver-pciback > >>+++ b/Documentation/ABI/testing/sysfs-driver-pciback > >>@@ -11,3 +11,15 @@ Description: > >> #echo 00:19.0-E0:2:FF > /sys/bus/pci/drivers/pciback/quirks > >> will allow the guest to read and write to the configuration > >> register 0x0E. > >>+ > >>+What: /sys/bus/pci/drivers/pciback/do_flr > >>+Date: Nov 2017 > >>+KernelVersion: 4.15 > >>+Contact: xen-devel@lists.xenproject.org > >>+Description: > >>+ An option to perform a slot or bus reset when a PCI device > >>+ is owned by Xen PCI backend. Writing a string of DDDD:BB:DD.F > >>+ will cause the pciback driver to perform a slot or bus reset > >>+ if the device supports it. It also checks to make sure that > >>+ all of the devices under the bridge are owned by Xen PCI > >>+ backend. > >Why do you name this "do_flr" when you don't even try FLR, but > >go to slot or then bus reset right away. > Yes, I agree but xen toolstack has already been modified to consume"do_flr" > attribute. Hence, we are using the > function that matches with sysfs attribute. > Hmm.. I remember some discussion from ages ago related to this. Back then it was suggested to "emulate" the flr capability (by doing slot or bus reset) for devices which don't have *native* flr available? So is this patch perhaps related to that? If the PCI device in question has native flr capability, then native flr is used, right ? I guess I should read the full patch.. -- Pasi