From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1163084AbeCAXOw (ORCPT ); Thu, 1 Mar 2018 18:14:52 -0500 Received: from mail-eopbgr670124.outbound.protection.outlook.com ([40.107.67.124]:45238 "EHLO CAN01-TO1-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1162910AbeCAXOt (ORCPT ); Thu, 1 Mar 2018 18:14:49 -0500 From: "Stephen Bates" To: Logan Gunthorpe , Bjorn Helgaas CC: "linux-kernel@vger.kernel.org" , "linux-pci@vger.kernel.org" , "linux-nvme@lists.infradead.org" , "linux-rdma@vger.kernel.org" , "linux-nvdimm@lists.01.org" , "linux-block@vger.kernel.org" , "Christoph Hellwig" , Jens Axboe , Keith Busch , Sagi Grimberg , Bjorn Helgaas , Jason Gunthorpe , Max Gurtovoy , Dan Williams , =?utf-8?B?SsOpcsO0bWUgR2xpc3Nl?= , Benjamin Herrenschmidt , Alex Williamson Subject: Re: [PATCH v2 01/10] PCI/P2PDMA: Support peer to peer memory Thread-Topic: [PATCH v2 01/10] PCI/P2PDMA: Support peer to peer memory Thread-Index: AQHTsO2GlGV4YX1/W0e8HoNGK6xZcKO7pjEAgAAVyYCAAEReAIAAAb+A//+M4gA= Date: Thu, 1 Mar 2018 23:14:46 +0000 Message-ID: <9B84B347-2CCF-4250-89ED-B29892E76597@raithlin.com> References: <20180228234006.21093-1-logang@deltatee.com> <20180228234006.21093-2-logang@deltatee.com> <20180301173752.GE13722@bhelgaas-glaptop.roam.corp.google.com> <20180301230032.GA74737@bhelgaas-glaptop.roam.corp.google.com> In-Reply-To: Accept-Language: en-CA, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: user-agent: Microsoft-MacOutlook/10.a.0.180210 authentication-results: spf=none (sender IP is ) smtp.mailfrom=sbates@raithlin.com; x-originating-ip: [70.65.224.121] x-ms-publictraffictype: Email x-microsoft-exchange-diagnostics: 1;YTXPR0101MB2175;7:UdM+EHI5Xv9KyIoJOBCYE6ydac7j0ynOuYaFrHNnSHymrlz4xsj3gysGh8XoueoqasroRJLsvCGKRXayS8Roqx5CrI+Fer/dVYlgIXAKkqMuGMRti/7MnHuK4gYFYWsOwp5LHqF/y+V6cjXMU8cCu1uKvWLdUjVaa/HoKBEsx0al0avhPr6NvhEnToyjhOBKfqrLwQqiG5eZ8oOJsNYmDBkyMJ99zv9L6wrIjckEV3DU1g3YO9Z0gJ2C+EUdBi6E x-ms-exchange-antispam-srfa-diagnostics: SSOS; x-ms-office365-filtering-correlation-id: 36cf24ec-216c-4639-c7ee-08d57fca3997 x-microsoft-antispam: UriScan:;BCL:0;PCL:0;RULEID:(7020095)(4652020)(7021125)(4534165)(7022125)(4603075)(4627221)(201702281549075)(7048125)(7024125)(7027125)(7028125)(7023125)(5600026)(4604075)(3008032)(2017052603307)(7153060)(7193020);SRVR:YTXPR0101MB2175; x-ms-traffictypediagnostic: YTXPR0101MB2175: x-microsoft-antispam-prvs: x-exchange-antispam-report-test: UriScan:(278428928389397); x-exchange-antispam-report-cfa-test: BCL:0;PCL:0;RULEID:(6040501)(2401047)(8121501046)(5005006)(10201501046)(3002001)(3231220)(944501232)(52105095)(93006095)(93001095)(6041288)(20161123560045)(20161123564045)(20161123558120)(20161123562045)(2016111802025)(6072148)(6043046)(201708071742011);SRVR:YTXPR0101MB2175;BCL:0;PCL:0;RULEID:;SRVR:YTXPR0101MB2175; x-forefront-prvs: 05986C03E0 x-forefront-antispam-report: SFV:NSPM;SFS:(10019020)(366004)(346002)(376002)(396003)(39380400002)(39830400003)(189003)(199004)(478600001)(4326008)(36756003)(3280700002)(2900100001)(2950100002)(3660700001)(5660300001)(14454004)(25786009)(551934003)(2906002)(83716003)(82746002)(102836004)(68736007)(86362001)(3846002)(26005)(105586002)(5250100002)(186003)(106356001)(6246003)(76176011)(58126008)(229853002)(110136005)(53936002)(66066001)(316002)(93886005)(54906003)(6436002)(8936002)(97736004)(6506007)(81156014)(81166006)(99286004)(8676002)(6116002)(6486002)(6512007)(33656002)(7416002)(7736002)(59450400001)(305945005);DIR:OUT;SFP:1102;SCL:1;SRVR:YTXPR0101MB2175;H:YTXPR0101MB2045.CANPRD01.PROD.OUTLOOK.COM;FPR:;SPF:None;PTR:InfoNoRecords;MX:1;A:1;LANG:en; x-microsoft-antispam-message-info: b6nqf85giztSHlp+D75/4a9F2PQfcoWpGsMR1nZiMXNjIbmSYfDnAgK3D/IR1FBK+CI8E0aJDBIVuYT3XoVSgyZr6HeGLgA+2lKTygbyH/l7V5uR+7wHHWjJpXL0TXtYJETuH/JTMj5o62yCXlzS20GDRXUgsnSpMTleV+DzTGU= spamdiagnosticoutput: 1:99 spamdiagnosticmetadata: NSPM Content-Type: text/plain; charset="utf-8" Content-ID: MIME-Version: 1.0 X-OriginatorOrg: raithlin.com X-MS-Exchange-CrossTenant-Network-Message-Id: 36cf24ec-216c-4639-c7ee-08d57fca3997 X-MS-Exchange-CrossTenant-originalarrivaltime: 01 Mar 2018 23:14:46.8225 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 18519031-7ff4-4cbb-bbcb-c3252d330f4b X-MS-Exchange-Transport-CrossTenantHeadersStamped: YTXPR0101MB2175 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from base64 to 8bit by mail.home.local id w21NEwdY024206 > I'm pretty sure the spec disallows routing-to-self so doing a P2P > transaction in that sense isn't going to work unless the device > specifically supports it and intercepts the traffic before it gets to > the port. This is correct. Unless the device intercepts the TLP before it hits the root-port then this would be considered a "route to self" violation and an error event would occur. The same holds for the downstream port on a PCI switch (unless route-to-self violations are disabled which violates the spec but which I have seen done in certain applications). Stephen