Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
IronPort-SDR: pinHYWFDPF+KbHbFyIk2TYU4el9he/7NWlZVRt/dtWze3Vqte5GShzLhMuMlYDDmik1D75UFH8
 Yasm+7whPSyg==
IronPort-SDR: wVbLfh9aWFL2/9GfBxHpYZmEEAV7tEylRLv/fqb0YV3dQ726YsntZpwpFP0NDxQehJmMxoO15D
 4ENmL9/KJgng==
From:   "Tian, Kevin" <kevin.tian@intel.com>
To:     Leon Romanovsky <leon@kernel.org>
CC:     Jason Gunthorpe <jgg@nvidia.com>,
        "Alex Williamson (alex.williamson@redhat.com)" 
        <alex.williamson@redhat.com>,
        "Jean-Philippe Brucker" <jean-philippe@linaro.org>,
        David Gibson <david@gibson.dropbear.id.au>,
        Jason Wang <jasowang@redhat.com>,
        "parav@mellanox.com" <parav@mellanox.com>,
        "Enrico Weigelt, metux IT consult" <lkml@metux.net>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Shenming Lu <lushenming@huawei.com>,
        Eric Auger <eric.auger@redhat.com>,
        Jonathan Corbet <corbet@lwn.net>,
        "Raj, Ashok" <ashok.raj@intel.com>,
        "Liu, Yi L" <yi.l.liu@intel.com>, "Wu, Hao" <hao.wu@intel.com>,
        "Jiang, Dave" <dave.jiang@intel.com>,
        Jacob Pan <jacob.jun.pan@linux.intel.com>,
        "Kirti Wankhede" <kwankhede@nvidia.com>,
        Robin Murphy <robin.murphy@arm.com>,
        "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
        "iommu@lists.linux-foundation.org" <iommu@lists.linux-foundation.org>,
        "David Woodhouse" <dwmw2@infradead.org>,
        Joerg Roedel <joro@8bytes.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Lu Baolu <baolu.lu@linux.intel.com>
Subject: RE: Plan for /dev/ioasid RFC v2
Thread-Topic: Plan for /dev/ioasid RFC v2
Thread-Index: AddbO/WEUAFl3MPnRsG8exiH8bwEagB0h8+AAAFDh8A=
Date:   Wed, 9 Jun 2021 09:43:42 +0000
Message-ID: <MWHPR11MB18860C8052D73508CF023AD28C369@MWHPR11MB1886.namprd11.prod.outlook.com>
References: <MWHPR11MB188699D0B9C10EB51686C4138C389@MWHPR11MB1886.namprd11.prod.outlook.com>
 <YMCDfWLw6r80Wdu3@unreal>
In-Reply-To: <YMCDfWLw6r80Wdu3@unreal>
Accept-Language: en-US
Content-Language: en-US
dlp-version: 11.5.1.3
dlp-product: dlpe-windows
dlp-reaction: no-action
x-ms-exchange-antispam-messagedata-chunkcount: 1
x-ms-exchange-antispam-messagedata-0: =?us-ascii?Q?kLAdEExpfYzex+MBTBlkhmtqhWiJBpIJJ+cZhQ5JO0ACwuNSTAQAIPI0Giwf?=
 =?us-ascii?Q?AsygfYFdabA4iUFaqyLFP4RlEHSUXQF19HdmWFZGwuZNqFYHdKouP/A6fJhB?=
 =?us-ascii?Q?Sh+iFOzk0RUrz1tx2uzTMPsS4PKFSoKovVqKcA+eYInxlyqxsKGrCUY8HEll?=
 =?us-ascii?Q?7oasYhaKQCMaNT28W4NkZqHtgYY0yYjexMi84VAuwRXkF3DUye1fViZhvR0S?=
 =?us-ascii?Q?aLeR1OsBxKy0G2+eyQ7V/crltJjrBfEqv99aeiT8uwdajqJFEh9Rjfta72b8?=
 =?us-ascii?Q?ePZ/q5be59uJ+oR07TNz2vb6RdEv3+Zjpqxpjj49mKxnSmdl8eZ+spMqL75q?=
 =?us-ascii?Q?wMisZfHtahL/6M6GhyP/mcgA9BNGIXWVN0d9o5Wv5ICrB1m3IUwyoyrg4VDb?=
 =?us-ascii?Q?C4BRlMxlvuhhEGPF44zp5J0PyH4htu1KsoEhiv2mwCXQWAS05x5YlNZ0KJRl?=
 =?us-ascii?Q?9Qq1yLQcLlwsbxHzyXOsFxTc/j0IvLvZ+55pORpyjnqVxATdI9ByWN5m80gX?=
 =?us-ascii?Q?Yec2Ft12Z/jpFIDISIGzn94yu7WKqMfRmOT5x8GxvPNLpo5NsFaHVoh+fZPf?=
 =?us-ascii?Q?SAzds0dOPw3jgevsGUxR/Dr/gg9fuAi7DU0sZf0Psg5UhqCU5gx8xUKFTEB0?=
 =?us-ascii?Q?iTeHxdlAj61mmyIOwIz1gwuUIeK3a1z/GFd85mLfwERewu26mSLtanwxMl/7?=
 =?us-ascii?Q?g4eHWHS3dCeE2qSkaRaSSJnVF0L0UhtuVK7kPuXC+DTCZex0eRv8KSwF7jQc?=
 =?us-ascii?Q?4O77au+lrwDBOnDNlflDbjdMjcoJRUmNhW62s0DeYjtM2MGkHJ79jxGwWGcp?=
 =?us-ascii?Q?moz4vG0M++Vm3PMxc7ThXLF4NGplx+hVFimaOdbCD34502QMYcYipBD2eAJD?=
 =?us-ascii?Q?RTC5NGtjm95pXEc7BSXSFj1SbrvqCexEebRl6gV2+4ctqkygNzSh/K//2GoG?=
 =?us-ascii?Q?C46ocoOnbFTlqwewrxvcDnWAhgv+AI6Gk1Uo7ky9fPz1/sGXUWn9TqLImelf?=
 =?us-ascii?Q?p9+xFMJlsnqVvLVv+nxJn8E7b5ATgsq98Yfy1hqCpE0TkEKFnkfPL4PI7rjs?=
 =?us-ascii?Q?H51rViYObU//gLmm+/m5j7kENi+BV7rjzWoYFszZ6Hlu7PClCujBciAlRRw9?=
 =?us-ascii?Q?uR1HTeOtBnfGb17Z6IzBddINUWO84jTZFOCDB0pgAzlg5oQQaIlBqX3PEsQt?=
 =?us-ascii?Q?yVqTfSOPiRqr79DPJa4S5364hgUBZhIbkY8W0QZMxIKoXnYoLN9WnZM5k+Yj?=
 =?us-ascii?Q?YTdSHz3Ks6LnWxAlGknlBWrd7Sv4RLTl1g17pUKtmiOjsAOqII20Psk2I6UW?=
 =?us-ascii?Q?hns=3D?=
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: quoted-printable
MIME-Version: 1.0
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-AuthSource: MWHPR11MB1886.namprd11.prod.outlook.com
X-MS-Exchange-CrossTenant-Network-Message-Id: 08d0a2d9-3973-4c2a-0968-08d92b2b11d6
X-MS-Exchange-CrossTenant-originalarrivaltime: 09 Jun 2021 09:43:42.9764
 (UTC)
X-MS-Exchange-CrossTenant-fromentityheader: Hosted
X-MS-Exchange-CrossTenant-id: 46c98d88-e344-4ed4-8496-4ed7712e255d
X-MS-Exchange-CrossTenant-mailboxtype: HOSTED
X-MS-Exchange-CrossTenant-userprincipalname: 0HwHjiFrRdIdwWFjZeBAmup8wK/V/qVHUrL570qUcVvWKv3UYjqGb7SCtW5T/IG0LbMqaeykcRqkRnH+lFNeow==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: MWHPR1101MB2224
X-OriginatorOrg: intel.com
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

> From: Leon Romanovsky <leon@kernel.org>
> Sent: Wednesday, June 9, 2021 5:02 PM
>=20
> On Mon, Jun 07, 2021 at 02:58:18AM +0000, Tian, Kevin wrote:
> > Hi, all,
>=20
> <...>
>=20
> > (Remaining opens in v1)
>=20
> <...>
>=20
> > -   Device-centric (Jason) vs. group-centric (David) uAPI. David is not=
 fully
> >     convinced yet. Based on discussion v2 will continue to have ioasid =
uAPI
> >     being device-centric (but it's fine for vfio to be group-centric). =
A new
> >     section will be added to elaborate this part;
>=20
> <...>
>=20
> > (Adopted suggestions)
>=20
> <...>
>=20
> > -   (Jason) Addition of device label allows per-device capability/forma=
t
> >     check before IOASIDs are created. This leads to another major uAPI
> >     change in v2 - specify format info when creating an IOASID (mapping
> >     protocol, nesting, coherent, etc.). User is expected to check per-d=
evice
> >     format and then set proper format for IOASID upon to-be-attached
> >     device;
>=20
> Sorry for my naive question, I still didn't read all v1 thread and maybe
> the answer is already written, but will ask anyway.
>=20
> Doesn't this adopted suggestion to allow device-specific configuration
> actually means that uAPI should be device-centric?
>=20
> User already needs to be aware of device, configure it explicitly, maybe
> gracefully clean it later, it looks like not so much left to be group-cen=
tric.
>=20

Yes, this is what v2 will lean toward. /dev/ioasid reports format info and=
=20
handle IOASID attachment per device. VFIO could still keep its group-
centric uAPI, but in the end it needs bind each device in the group to=20
IOASID FD one-by-one.=20

Thanks
Kevin