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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS 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 DA638C67790 for ; Wed, 25 Jul 2018 02:06:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9EB4620883 for ; Wed, 25 Jul 2018 02:06:51 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9EB4620883 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388501AbeGYDQJ (ORCPT ); Tue, 24 Jul 2018 23:16:09 -0400 Received: from mga05.intel.com ([192.55.52.43]:47049 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388461AbeGYDQI (ORCPT ); Tue, 24 Jul 2018 23:16:08 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by fmsmga105.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 24 Jul 2018 19:06:49 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.51,400,1526367600"; d="scan'208";a="67299639" Received: from blu2-desk2.ccr.corp.intel.com (HELO [10.0.2.15]) ([10.239.13.1]) by FMSMGA003.fm.intel.com with ESMTP; 24 Jul 2018 19:06:44 -0700 Subject: Re: [RFC PATCH 03/10] iommu/vt-d: Allocate groups for mediated devices To: Jean-Philippe Brucker , "Liu, Yi L" , Joerg Roedel , David Woodhouse , Alex Williamson , Kirti Wankhede References: <1532239773-15325-1-git-send-email-baolu.lu@linux.intel.com> <1532239773-15325-4-git-send-email-baolu.lu@linux.intel.com> <5B568D5B.5050606@linux.intel.com> Cc: "Raj, Ashok" , "kvm@vger.kernel.org" , "Kumar, Sanjay K" , "iommu@lists.linux-foundation.org" , "linux-kernel@vger.kernel.org" , "Sun, Yi Y" , "Pan, Jacob jun" , "Tian, Kevin" From: Lu Baolu Message-ID: <5B57DB30.6070306@linux.intel.com> Date: Wed, 25 Jul 2018 10:06:40 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.5.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Jean, Pull Kevin in. Not sure why he was removed from cc list. On 07/24/2018 07:30 PM, Jean-Philippe Brucker wrote: > Hi Baolu, > > On 24/07/18 03:22, Lu Baolu wrote: >> Hi, >> >> On 07/23/2018 12:44 PM, Liu, Yi L wrote: >>>> From: Lu Baolu [mailto:baolu.lu@linux.intel.com] >>>> Sent: Sunday, July 22, 2018 2:09 PM >>>> >>>> With the Intel IOMMU supporting PASID granularity isolation and protection, a >>>> mediated device could be isolated and protected by an IOMMU unit. We need to >>>> allocate a new group instead of a PCI group. >>> Existing vfio mdev framework also allocates an iommu group for mediate device. >>> >>> mdev_probe() >>> |_ mdev_attach_iommu() >>> |_ iommu_group_alloc() >> When external components ask iommu to allocate a group for a device, >> it will call pci_device_group in Intel IOMMU driver's @device_group >> callback. In another word, current Intel IOMMU driver doesn't aware >> the mediated device and treat all devices as PCI ones. This patch >> extends the @device_group call back to make it aware of a mediated >> device. > I agree that allocating two groups for an mdev seems strange, and in my > opinion we shouldn't export the notion of mdev to IOMMU drivers. > Otherwise each driver will have to add its own "dev_is_mdev()" special > cases, which will get messy in the long run. Besides, the macro is > currently private, and to be exported it should be wrapped in > symbol_get/put(mdev_bus_type). I agree with you. It should be better if we can make it in a driver agnostic way. > > There is another way: as we're planning to add a generic pasid_alloc() > function to the IOMMU API, the mdev module itself could allocate a > default PASID for each mdev by calling pasid_alloc() on the mdev's > parent, and then do map()/unmap() with that PASID. This way we don't > have to add IOMMU ops to the mdev bus, everything can still be done > using the ops of the parent. And IOMMU drivers "only" have to implement > PASID ops, which will be reused by drivers other than mdev. A quick question when I thinking about this is how to allocate a domain for the mediated device who uses the default pasid for DMA transactions? Best regards, Lu Baolu > > The allocated PASID also needs to be installed into the parent device. > If the mdev module knows the PASID, we can do that by adding > set_pasid(mdev, pasid) and clear_pasid(mdev, pasid) operations to > mdev_parent_ops. > > Thanks, > Jean > >