From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752310AbdK3OQZ (ORCPT ); Thu, 30 Nov 2017 09:16:25 -0500 Received: from aserp1040.oracle.com ([141.146.126.69]:50328 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751819AbdK3OQX (ORCPT ); Thu, 30 Nov 2017 09:16:23 -0500 Subject: Re: [Xen-devel] [PATCH V2] Xen/pciback: Implement PCI slot or bus reset with 'do_flr' SysFS attribute To: Jan Beulich Cc: roger.pau@citrix.com, xen-devel@lists.xenproject.org, boris.ostrovsky@oracle.com, Juergen Gross , linux-kernel@vger.kernel.org References: <20171108230654.2981-1-Govinda.Tatti@Oracle.COM> <5A0424B7020000780018D6FA@prv-mh.provo.novell.com> <5A1EE54D020000780019335F@prv-mh.provo.novell.com> <2783ea8a-3ef3-c4dd-a592-52cf8e188ad4@oracle.com> <5A1FCF150200007800193632@prv-mh.provo.novell.com> From: Govinda Tatti Organization: Oracle Corporation Message-ID: <71644190-6e18-94a4-4da5-e65c041fb45a@oracle.com> Date: Thu, 30 Nov 2017 08:15:25 -0600 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.5.0 MIME-Version: 1.0 In-Reply-To: <5A1FCF150200007800193632@prv-mh.provo.novell.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US X-Source-IP: aserv0021.oracle.com [141.146.126.233] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/30/2017 2:27 AM, Jan Beulich wrote: >>>> On 29.11.17 at 18:38, wrote: >>>> In the case of bus or slot reset, our goal is to reset connected PCIe >>>> fabric/card/endpoint. >>>> The connected card/endpoint can be multi-function device. So, same >>>> walk-through and checking >>>> is needed irrespective of type of reset being used. >>> I don't follow: The scope of other devices/functions possibly >>> affected by a reset depends on the type of reset, doesn't it? >> For PCIe platforms, both slot and bus reset endup resetting all connected >> device/functions on thesecondary bus (behind the root-port or >> downstream-port). > According to my understanding this contradicts the comment > ahead of pci_reset_slot(), which talks of multiple slots per bus. > In such a setup, I can't see why resetting on slot would affect > other slots on the same bus. At the same time the comment > says that the slot reset may resolve to a bus one when there's > just a single slot on the bus. For legacy PCI/PCI-X, we can have multiple slots per bus but not with PCI-Express (each link will be on a separate bus). In anycase, we need to walk-through other device/functions on the same bus/slot and check their status before using slot/bus reset. Cheers GOVINDA