From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <SRS0=IfBm=EJ=vger.kernel.org=kvm-owner@kernel.org>
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=-3.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH,
	DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,
	MAILING_LIST_MULTI,MSGID_FROM_MTA_HEADER,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED
	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 93C81C2D0A3
	for <kvm@archiver.kernel.org>; Tue,  3 Nov 2020 14:06:55 +0000 (UTC)
Received: from vger.kernel.org (vger.kernel.org [23.128.96.18])
	by mail.kernel.org (Postfix) with ESMTP id 30F0422264
	for <kvm@archiver.kernel.org>; Tue,  3 Nov 2020 14:06:55 +0000 (UTC)
Authentication-Results: mail.kernel.org;
	dkim=pass (2048-bit key) header.d=nvidia.com header.i=@nvidia.com header.b="nU+/k4+R"
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1729525AbgKCOGy (ORCPT <rfc822;kvm@archiver.kernel.org>);
        Tue, 3 Nov 2020 09:06:54 -0500
Received: from hqnvemgate26.nvidia.com ([216.228.121.65]:9392 "EHLO
        hqnvemgate26.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S1729523AbgKCOGu (ORCPT <rfc822;kvm@vger.kernel.org>);
        Tue, 3 Nov 2020 09:06:50 -0500
Received: from hqmail.nvidia.com (Not Verified[216.228.121.13]) by hqnvemgate26.nvidia.com (using TLS: TLSv1.2, AES256-SHA)
        id <B5fa163fc0002>; Tue, 03 Nov 2020 06:06:52 -0800
Received: from HQMAIL101.nvidia.com (172.20.187.10) by HQMAIL107.nvidia.com
 (172.20.187.13) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Tue, 3 Nov
 2020 14:06:45 +0000
Received: from NAM11-CO1-obe.outbound.protection.outlook.com (104.47.56.175)
 by HQMAIL101.nvidia.com (172.20.187.10) with Microsoft SMTP Server (TLS) id
 15.0.1473.3 via Frontend Transport; Tue, 3 Nov 2020 14:06:45 +0000
ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none;
 b=m4UxEn+/fHQtpvT5H+TAhf3DpIjB/7o3zw5WURYNYQozMACb9Z8ihV59kHEyacwXG/90M1sdS4tvb3sNoyKWyZ1g79YOCdmGfCpj9u9759QBXOsHRaf3S6Hj6egsjwu/sUw/d+b8U44CvCjYNsqYUgDmJY2qA1nhcf9dwZmy9/tg6dgAY8THBb8Vj3NBAbgWb8pA7W5vicmocd6u6Bw2Zju7b9SHYMUvum2uswI+fyub1grjnow7l9+6yOM6gZRGZa8i1pnsAmYjRsEmT7K5uQ6pD/0u5939zAUaofB/Frg+Yqs/n0hw1ChS7QQ7q0NwMuqU35rd2iSo1yAVWii4zg==
ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com;
 s=arcselector9901;
 h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck;
 bh=tLIrEYoCMgNKeogVNQHUSSTMtD3XOjJCaLnrinaavuY=;
 b=mZZ0F8fdRUpSsxXyWE+Yql0pMVeg5n1RKzzbVMoCB6IdB0Pb1r+qUIX1zzcSiaHP5nDUabevCWey8Ys/ttqAF++PlhpzzwXNN7jxGuKVSZ2OduxcHK5HzUhcTYO9+XmJ1t5VAERV7McDEiSTXs+HoM77T4nH2aHEQ7tsEWI0D2KTW2Um94XGFq8LH7BjPJUOCoCxGb6bYOesgqQYG+q08Ayfh7UY2MJOzJPSWWIKxmWvF1KwAZDNaS7H91qNf0BOQvJAxTdocePUB6Bs6+EZPcU9wOHoKVNA9R2NLUfALMbJNjStpI3+TO3P0Cf0mdaHBP1PdjfmiD+7h9oLzg7n2Q==
ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass
 smtp.mailfrom=nvidia.com; dmarc=pass action=none header.from=nvidia.com;
 dkim=pass header.d=nvidia.com; arc=none
Received: from BY5PR12MB3827.namprd12.prod.outlook.com (2603:10b6:a03:1ab::16)
 by BYAPR12MB3047.namprd12.prod.outlook.com (2603:10b6:a03:d9::28) with
 Microsoft SMTP Server (version=TLS1_2,
 cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3499.29; Tue, 3 Nov
 2020 14:06:44 +0000
Received: from BY5PR12MB3827.namprd12.prod.outlook.com
 ([fe80::2459:e095:ac09:34e5]) by BY5PR12MB3827.namprd12.prod.outlook.com
 ([fe80::2459:e095:ac09:34e5%6]) with mapi id 15.20.3499.031; Tue, 3 Nov 2020
 14:06:44 +0000
Date:   Tue, 3 Nov 2020 10:06:42 -0400
From:   Jason Gunthorpe <jgg@nvidia.com>
To:     "joro@8bytes.org" <joro@8bytes.org>
CC:     "Tian, Kevin" <kevin.tian@intel.com>,
        Jason Wang <jasowang@redhat.com>,
        "Liu, Yi L" <yi.l.liu@intel.com>,
        "alex.williamson@redhat.com" <alex.williamson@redhat.com>,
        "eric.auger@redhat.com" <eric.auger@redhat.com>,
        "baolu.lu@linux.intel.com" <baolu.lu@linux.intel.com>,
        "jacob.jun.pan@linux.intel.com" <jacob.jun.pan@linux.intel.com>,
        "Raj, Ashok" <ashok.raj@intel.com>,
        "Tian, Jun J" <jun.j.tian@intel.com>,
        "Sun, Yi Y" <yi.y.sun@intel.com>,
        "jean-philippe@linaro.org" <jean-philippe@linaro.org>,
        "peterx@redhat.com" <peterx@redhat.com>,
        "Wu, Hao" <hao.wu@intel.com>,
        "stefanha@gmail.com" <stefanha@gmail.com>,
        "iommu@lists.linux-foundation.org" <iommu@lists.linux-foundation.org>,
        "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
        "Michael S. Tsirkin" <mst@redhat.com>
Subject: Re: (proposal) RE: [PATCH v7 00/16] vfio: expose virtual Shared
 Virtual Addressing to VMs
Message-ID: <20201103140642.GQ2620339@nvidia.com>
References: <MWHPR11MB1645CFB0C594933E92A844AC8C070@MWHPR11MB1645.namprd11.prod.outlook.com>
 <20201103095208.GA22888@8bytes.org> <20201103125643.GN2620339@nvidia.com>
 <20201103131852.GE22888@8bytes.org> <20201103132335.GO2620339@nvidia.com>
 <20201103140318.GL22888@8bytes.org>
Content-Type: text/plain; charset="us-ascii"
Content-Disposition: inline
In-Reply-To: <20201103140318.GL22888@8bytes.org>
X-ClientProxiedBy: BL0PR02CA0006.namprd02.prod.outlook.com
 (2603:10b6:207:3c::19) To BY5PR12MB3827.namprd12.prod.outlook.com
 (2603:10b6:a03:1ab::16)
MIME-Version: 1.0
X-MS-Exchange-MessageSentRepresentingType: 1
Received: from mlx.ziepe.ca (156.34.48.30) by BL0PR02CA0006.namprd02.prod.outlook.com (2603:10b6:207:3c::19) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3499.18 via Frontend Transport; Tue, 3 Nov 2020 14:06:44 +0000
Received: from jgg by mlx with local (Exim 4.94)        (envelope-from <jgg@nvidia.com>)        id 1kZwxO-00Fuj7-FU; Tue, 03 Nov 2020 10:06:42 -0400
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1;
        t=1604412412; bh=tLIrEYoCMgNKeogVNQHUSSTMtD3XOjJCaLnrinaavuY=;
        h=ARC-Seal:ARC-Message-Signature:ARC-Authentication-Results:Date:
         From:To:CC:Subject:Message-ID:References:Content-Type:
         Content-Disposition:In-Reply-To:X-ClientProxiedBy:MIME-Version:
         X-MS-Exchange-MessageSentRepresentingType;
        b=nU+/k4+R/klPpRJlMpPJUBzeKasLIzMsSfN9rPXsFszw26/2iJ7PyE10UtIL72wgt
         +0T81QWYw2HPLe/+rfr9T+YvW03zAMYk+2ytghpHdBtaiUllBkwkGVXmvC0F/Tlz0i
         nMXuYTj3hc5Vpj0pAnlS40Ky992BFIsJ8qISfxCUwHtA660JeUAf5Rm3uPuTVqmnwO
         hOEft0q79WNdjx+xTe4qmSF+9EceFeT3gJbcWzJ8jmWRGiSurL2LD/Qm8dwbbAa/mp
         ZJg9+UAmvo7JMrRTe9UOLZJU/cy2tCtwitCpjcatQ63uZFNw5ZL3fMcUDKyAbNluy1
         4lkqvgkbHVQBA==
Precedence: bulk
List-ID: <kvm.vger.kernel.org>
X-Mailing-List: kvm@vger.kernel.org

On Tue, Nov 03, 2020 at 03:03:18PM +0100, joro@8bytes.org wrote:
> On Tue, Nov 03, 2020 at 09:23:35AM -0400, Jason Gunthorpe wrote:
> > Userspace needs fine grained control over the composition of the page
> > table behind the PASID, 1:1 with the mm_struct is only one use case.
> 
> VFIO already offers an interface for that. It shouldn't be too
> complicated to expand that for PASID-bound page-tables.
> 
> > Userspace needs to be able to handle IOMMU faults, apparently
> 
> Could be implemented by a fault-fd handed out by VFIO.

The point is that other places beyond VFIO need this

> I really don't think that user-space should have to deal with details
> like PASIDs or other IOMMU internals, unless absolutly necessary. This
> is an OS we work on, and the idea behind an OS is to abstract the
> hardware away.

Sure, but sometimes it is necessary, and in those cases the answer
can't be "rewrite a SVA driver to use vfio"

Jason