From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934527AbeEIMgF (ORCPT ); Wed, 9 May 2018 08:36:05 -0400 Received: from mail-eopbgr670136.outbound.protection.outlook.com ([40.107.67.136]:52583 "EHLO CAN01-TO1-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S932875AbeEIMf7 (ORCPT ); Wed, 9 May 2018 08:35:59 -0400 From: "Stephen Bates" To: Alex Williamson , Don Dutile CC: Dan Williams , Logan Gunthorpe , Linux Kernel Mailing List , "linux-pci@vger.kernel.org" , "linux-nvme@lists.infradead.org" , linux-rdma , linux-nvdimm , "linux-block@vger.kernel.org" , Christoph Hellwig , Jens Axboe , Keith Busch , Sagi Grimberg , Bjorn Helgaas , Jason Gunthorpe , Max Gurtovoy , =?utf-8?B?SsOpcsO0bWUgR2xpc3Nl?= , Benjamin Herrenschmidt , =?utf-8?B?Q2hyaXN0aWFuIEvDtm5pZw==?= Subject: Re: [PATCH v4 04/14] PCI/P2PDMA: Clear ACS P2P flags for all devices behind switches Thread-Topic: [PATCH v4 04/14] PCI/P2PDMA: Clear ACS P2P flags for all devices behind switches Thread-Index: AQHT21soiBVnp6SJuEuLCiH6kBzTLKQl+8wA//+fHICAAM6PgP//ogsAgACAHoCAAA+NgIAAbhQA Date: Wed, 9 May 2018 12:35:56 +0000 Message-ID: References: <20180423233046.21476-1-logang@deltatee.com> <20180423233046.21476-5-logang@deltatee.com> <64C231F5-DE36-415F-B308-3A423B0BBACB@raithlin.com> <15433946-f7f5-f610-4e80-380fb59920e5@redhat.com> <3C9FB262-A93C-4C8F-B1E0-85C6D6F78BC2@raithlin.com> <20180508180157.7c7b393f@w520.home> In-Reply-To: <20180508180157.7c7b393f@w520.home> Accept-Language: en-CA, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: user-agent: Microsoft-MacOutlook/10.d.0.180505 authentication-results: spf=none (sender IP is ) smtp.mailfrom=sbates@raithlin.com; 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charset="utf-8" Content-ID: <1637E91BB2F65F4B8ECDBB1A7D276542@CANPRD01.PROD.OUTLOOK.COM> MIME-Version: 1.0 X-MS-Office365-Filtering-Correlation-Id: eb6083cb-95a3-4b2c-3294-08d5b5a96992 X-OriginatorOrg: raithlin.com X-MS-Exchange-CrossTenant-Network-Message-Id: eb6083cb-95a3-4b2c-3294-08d5b5a96992 X-MS-Exchange-CrossTenant-originalarrivaltime: 09 May 2018 12:35:56.7301 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 18519031-7ff4-4cbb-bbcb-c3252d330f4b X-MS-Exchange-Transport-CrossTenantHeadersStamped: YTOPR0101MB2217 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 w49CaCCK004333 Hi Alex and Don > Correct, the VM has no concept of the host's IOMMU groups, only the > hypervisor knows about the groups, But as I understand it these groups are usually passed through to VMs on a pre-group basis by the hypervisor? So IOMMU group 1 might be passed to VM A and IOMMU group 2 passed to VM B. So I agree the VM is not aware of IOMMU groupings but it is impacted by them in the sense that if the groupings change the PCI topology presented to the VM needs to change too. Stephen