From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7D05FC43381 for ; Thu, 28 Feb 2019 14:09:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3BC632133D for ; Thu, 28 Feb 2019 14:09:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731990AbfB1OJw (ORCPT ); Thu, 28 Feb 2019 09:09:52 -0500 Received: from 8bytes.org ([81.169.241.247]:55970 "EHLO theia.8bytes.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727847AbfB1OJv (ORCPT ); Thu, 28 Feb 2019 09:09:51 -0500 Received: by theia.8bytes.org (Postfix, from userid 1000) id 6F0494A3; Thu, 28 Feb 2019 15:09:50 +0100 (CET) Date: Thu, 28 Feb 2019 15:09:50 +0100 From: Joerg Roedel To: Jacob Pan Cc: Jean-Philippe Brucker , iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, christian.koenig@amd.com, kevin.tian@intel.com, ashok.raj@intel.com, baolu.lu@linux.intel.com, alex.williamson@redhat.com Subject: Re: [PATCH 1/1] iommu: Bind process address spaces to devices Message-ID: <20190228140950.GD1594@8bytes.org> References: <20190220142759.33308-1-jean-philippe.brucker@arm.com> <20190220142759.33308-2-jean-philippe.brucker@arm.com> <20190226111743.GK20740@8bytes.org> <20190227134129.51ad42ac@jacob-builder> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190227134129.51ad42ac@jacob-builder> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Jacob, On Wed, Feb 27, 2019 at 01:41:29PM -0800, Jacob Pan wrote: > On Tue, 26 Feb 2019 12:17:43 +0100 > Joerg Roedel wrote: > Just trying to understand how to use this API. > So if we bind the same mm to two different devices, we should get two > different iommu_sva handle, right? > I think intel-svm still needs a flag argument for supervisor pasid etc. > Other than that, I think both interface should work for vt-d. I second Jean's question here, is supervisor pasid still needed with scalable mode? What is the use-case and which mm_struct will be used for supervisor accesses? > Another question is that for nested SVA, we will need to bind guest mm. > Do you think we should try to reuse this or have it separate? I am > working on a separate API for now. I think a separate API makes more sense. It could be somehow fit into this as well, but having it separate is cleaner. And we already have separate API for aux-domains, so this would be just another extension of the IOMMU-API for using PASIDs. > > int iommu_sva_get_pasid(struct iommu_sva *handle); > If multiple bind to the same mm gets multiple handles, this API should > retrieve the same pasid for different handle? It can return the same handle if we store the pasid in the mm_struct, for example ... > Just curious why making the handle private instead of returning the > pasid value in the handle? ... which is also the reason why I prefer the accessor function, it allows to have the pasid not in the iommu_sva handle, but to retrieve it from somewhere else (like the mm_struct). Regards, Joerg