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=-5.9 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 C6422C4708F for ; Wed, 2 Jun 2021 04:50:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A531C610E7 for ; Wed, 2 Jun 2021 04:50:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229684AbhFBEwO (ORCPT ); Wed, 2 Jun 2021 00:52:14 -0400 Received: from szxga02-in.huawei.com ([45.249.212.188]:3500 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229571AbhFBEwM (ORCPT ); Wed, 2 Jun 2021 00:52:12 -0400 Received: from dggemv704-chm.china.huawei.com (unknown [172.30.72.55]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4FvxNH3C1RzYq8c; Wed, 2 Jun 2021 12:47:43 +0800 (CST) Received: from dggpemm500022.china.huawei.com (7.185.36.162) by dggemv704-chm.china.huawei.com (10.3.19.47) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Wed, 2 Jun 2021 12:50:27 +0800 Received: from [10.174.185.220] (10.174.185.220) by dggpemm500022.china.huawei.com (7.185.36.162) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Wed, 2 Jun 2021 12:50:26 +0800 Subject: Re: [RFC] /dev/ioasid uAPI proposal To: Jason Gunthorpe , Lu Baolu CC: "Tian, Kevin" , LKML , Joerg Roedel , David Woodhouse , "iommu@lists.linux-foundation.org" , "kvm@vger.kernel.org" , "Alex Williamson (alex.williamson@redhat.com)" , Jason Wang , Eric Auger , Jonathan Corbet , "Raj, Ashok" , "Liu, Yi L" , "Wu, Hao" , "Jiang, Dave" , Jacob Pan , Jean-Philippe Brucker , David Gibson , Kirti Wankhede , "Robin Murphy" , Zenghui Yu , "wanghaibin.wang@huawei.com" References: <01fe5034-42c8-6923-32f1-e287cc36bccc@linux.intel.com> <20210601173323.GN1002214@nvidia.com> From: Shenming Lu Message-ID: <23a482f9-b88a-da98-3800-f3fd9ea85fbd@huawei.com> Date: Wed, 2 Jun 2021 12:50:26 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.2.2 MIME-Version: 1.0 In-Reply-To: <20210601173323.GN1002214@nvidia.com> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.185.220] X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) To dggpemm500022.china.huawei.com (7.185.36.162) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021/6/2 1:33, Jason Gunthorpe wrote: > On Tue, Jun 01, 2021 at 08:30:35PM +0800, Lu Baolu wrote: > >> The drivers register per page table fault handlers to /dev/ioasid which >> will then register itself to iommu core to listen and route the per- >> device I/O page faults. > > I'm still confused why drivers need fault handlers at all? Essentially it is the userspace that needs the fault handlers, one case is to deliver the faults to the vIOMMU, and another case is to enable IOPF on the GPA address space for on-demand paging, it seems that both could be specified in/through the IOASID_ALLOC ioctl? Thanks, Shenming