From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753103AbdKHX1V (ORCPT ); Wed, 8 Nov 2017 18:27:21 -0500 Received: from userp1040.oracle.com ([156.151.31.81]:27301 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753023AbdKHX1U (ORCPT ); Wed, 8 Nov 2017 18:27:20 -0500 Subject: Re: [Xen-devel] [PATCH] Xen/pciback: Implement PCI slot or bus reset with 'do_flr' SysFS attribute To: =?UTF-8?B?UGFzaSBLw6Rya2vDpGluZW4=?= Cc: Juergen Gross , Konrad Wilk , linux-kernel@vger.kernel.org, Jan Beulich , xen-devel@lists.xenproject.org, Boris Ostrovsky References: <20171106174842.20276-1-Govinda.Tatti@Oracle.COM> <5A01D3F3020000780018CE86@prv-mh.provo.novell.com> <8940b38d-715c-9fcb-cc74-46574d416703@oracle.com> <20171108173808.GH20756@reaktio.net> From: Govinda Tatti Organization: Oracle Corporation Message-ID: <41dc8296-a1c6-5d1b-4282-ee7338476063@oracle.com> Date: Wed, 8 Nov 2017 17:26:47 -0600 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.4.0 MIME-Version: 1.0 In-Reply-To: <20171108173808.GH20756@reaktio.net> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Source-IP: aserv0022.oracle.com [141.146.126.234] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Thanks Pasi for your response. Please see below for my comments. On 11/8/2017 11:38 AM, Pasi Kärkkäinen wrote: > 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? I don't think so but either Konrad or someone can comment on it. > > If the PCI device in question has native flr capability, then native flr is used, right ? Yes. > I guess I should read the full patch.. Please check it and let us know your comments. Cheers GOVINDA