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: xaNVv+osq1ONl1k/sn+JuVqALszLi/4otbkjLu9N1cjNKt2kn/ZYIK+tZujZIH+kwbPEXS187z
 om05wSvkxSAQ==
IronPort-SDR: iG598vUl0++JcPL0AY6F7Wy4zxfWbG5QD/ePyblkkDHHMOFmfHmrEkYprxNEwtpNQQzs94ozXF
 zWJ2DiBK+y9Q==
From:   "Tian, Kevin" <kevin.tian@intel.com>
To:     Jason Gunthorpe <jgg@nvidia.com>
CC:     Jean-Philippe Brucker <jean-philippe@linaro.org>,
        "Alex Williamson (alex.williamson@redhat.com)" 
        <alex.williamson@redhat.com>, "Raj, Ashok" <ashok.raj@intel.com>,
        "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
        "Jonathan Corbet" <corbet@lwn.net>,
        Robin Murphy <robin.murphy@arm.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Kirti Wankhede <kwankhede@nvidia.com>,
        "iommu@lists.linux-foundation.org" <iommu@lists.linux-foundation.org>,
        "David Gibson" <david@gibson.dropbear.id.au>,
        "Jiang, Dave" <dave.jiang@intel.com>,
        David Woodhouse <dwmw2@infradead.org>,
        Jason Wang <jasowang@redhat.com>
Subject: RE: [RFC] /dev/ioasid uAPI proposal
Thread-Topic: [RFC] /dev/ioasid uAPI proposal
Thread-Index: AddSzQ97BhCb3gd8AUyldaDZ6yOMNABTUTCAAQiuDaAADwOFgAJSmyVgAA0fjwAAEFKEEAAASwWAAAAgcXAAATmRgAAAC9RgAACZuQAAAAd+oA==
Date:   Wed, 16 Jun 2021 00:02:19 +0000
Message-ID: <MWHPR11MB1886298A9D202A966F1D4DA68C0F9@MWHPR11MB1886.namprd11.prod.outlook.com>
References: <20210528233649.GB3816344@nvidia.com>
 <MWHPR11MB188621A9D1181A414D5491198C3C9@MWHPR11MB1886.namprd11.prod.outlook.com>
 <20210603130519.GY1002214@nvidia.com>
 <MWHPR11MB1886BA2258AFD92D5249AC488C309@MWHPR11MB1886.namprd11.prod.outlook.com>
 <20210615150630.GS1002214@nvidia.com>
 <MWHPR11MB1886E9553A5054DF7D51F27D8C309@MWHPR11MB1886.namprd11.prod.outlook.com>
 <20210615230215.GA1002214@nvidia.com>
 <MWHPR11MB1886A0CAB3AFF424A4A090038C309@MWHPR11MB1886.namprd11.prod.outlook.com>
 <20210615234057.GC1002214@nvidia.com>
 <MWHPR11MB1886FD4121F754A6F7C2102A8C309@MWHPR11MB1886.namprd11.prod.outlook.com>
 <20210615235928.GD1002214@nvidia.com>
In-Reply-To: <20210615235928.GD1002214@nvidia.com>
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?x/JVhxiaCNFDsBzN3ZEjVHF7yjKJZ3iS42S/aDQLGwkkug/ymnvg/OOkM1Af?=
 =?us-ascii?Q?YmBDXtYofF0McXCXtTqhd/pcTnbI74lKnZmcso8bBVXY8lml4ECJOXdw9G9P?=
 =?us-ascii?Q?ppbjWJ+NnwMnOwF+PlBBrJCNLtOyQHhSu9kDx7W/VM/gqpuA2up4BTSu7Q5t?=
 =?us-ascii?Q?agS62DOhijXFEm9xB380j/Eu6pE6spJ95L1YryXsGPiXm0vTN9TADJiZ7gRE?=
 =?us-ascii?Q?CTsupo+r4Tjffy62sv+8v4zDG4oE0eICnKxOaMJ+1zl45xR0FLyVM0d5lZs+?=
 =?us-ascii?Q?wyjxZmZPYViWGBKjalcBU1Jv4FiJQ6rZ75DxrUy9qF7CK92k0HCW3KcaT5x/?=
 =?us-ascii?Q?8KxmzZKx07jSIn7/Bo+kMycOg+1bObVYHzsx/lOEzoMzJI9IFP0kpYZRzZLe?=
 =?us-ascii?Q?5t7VCUJJ8ywIXz9XkBfVCbsNJ/y2bbM7TBPgGAMPKGd6jDMG8MCREuNbbeDX?=
 =?us-ascii?Q?IZKk1HHeBCbrVjckau257f2QYnS2w5S1HUgxjQtChY0J4npWd1qtj8QlYMjy?=
 =?us-ascii?Q?WCuF4htgjc0qoZdyBWtriik0OtuyufxgyD9/BOaOVMvlO5pmqxTotJhPeXcL?=
 =?us-ascii?Q?OTZq12iciVUoypeCT+NZKXRRzebToNUhww36SerIxRyPyYXd9J91Y0qkJtGH?=
 =?us-ascii?Q?0fDoGv1dWGpXHwtf7GAR6ZlJVThiz01CR+l9A0f6YVXKPDAvDAJONv/xN8Eq?=
 =?us-ascii?Q?b8RmQz20LswefYBHkojstQ/FlzXLjRZJIho/U2EHGLiE1kMqTcTZn4jNfhQP?=
 =?us-ascii?Q?n963Lk1VqBbahYRmWVgnsvKQW70GZ/IcxMb2/oAi8zdyCqdHiMopX3DnScDh?=
 =?us-ascii?Q?adfRpNFXe4cNrIEV+nCq7+5ciRc4vPd9Xr+g2FPpcUpbrJdCFdD8pvkiEQ9J?=
 =?us-ascii?Q?51UzLqWZPYbeZtReJqXgmx8KIqKC8nqjFbjVnqlGZ8G9qBNiLKI+HjQGCN56?=
 =?us-ascii?Q?DT4Skf3b1a0Zl9qX3krPwVdf8DD2w0uY15fFj5XMgXlcvP/MsyelVOpjOVhD?=
 =?us-ascii?Q?zthUgrEQ6huoKPulEeLrC53XTVF4/bht2/UyLc/b5XapZHb3DDR2NDePM/Ro?=
 =?us-ascii?Q?H+bLBSJCdWh+6/FEvEwEdyiugznswF3PsGaTlYI5ivNPixnzTBF0XpVMj1HG?=
 =?us-ascii?Q?TKhz/rwremSnx47dUtHRqPP4VHidwrpP/TPRXZSZUOd/3POfvDhMPPN1D/sQ?=
 =?us-ascii?Q?J430hiBETkjHjd8eB06sW1J6bUQPi5VnFbUnUmwJzgFXCxO0cheoL+Jd+A3C?=
 =?us-ascii?Q?4MdEjRDvmH0oINUHaj2hEkOMnyTqT7UUw+IR4ukDqHzQDAnS6WIe2wl0bkud?=
 =?us-ascii?Q?0Dd6SspJhAI5RzbuiSdSHPFi?=
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: 2a6a79d6-ea2a-479e-d5a9-08d9305a026d
X-MS-Exchange-CrossTenant-originalarrivaltime: 16 Jun 2021 00:02:19.5158
 (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: hH48+eHxUiYbhaAs583sUrS3ygZq+Ds6UhbmxjLyN5lUOWQLQaR4xVfQWobN/ihB4bzhyNefDEENyuJAZrtaIg==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: MWHPR1101MB2128
X-OriginatorOrg: intel.com
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

> From: Jason Gunthorpe <jgg@nvidia.com>
> Sent: Wednesday, June 16, 2021 7:59 AM
>=20
> On Tue, Jun 15, 2021 at 11:56:28PM +0000, Tian, Kevin wrote:
> > > From: Jason Gunthorpe <jgg@nvidia.com>
> > > Sent: Wednesday, June 16, 2021 7:41 AM
> > >
> > > On Tue, Jun 15, 2021 at 11:09:37PM +0000, Tian, Kevin wrote:
> > >
> > > > which information can you elaborate? This is the area which I'm not
> > > > familiar with thus would appreciate if you can help explain how thi=
s
> > > > bus specific information is utilized within the attach function or
> > > > sometime later.
> > >
> > > This is the idea that the device driver needs to specify which bus
> > > specific protocol it uses to issue DMA's when it attaches itself to a=
n
> > > IOASID. For PCI:
> >
> > What about defining some general attributes instead of asking iommu
> > fd to understand those bus specific detail?
>=20
> I prefer the API be very clear and intent driven, otherwise things
> just get confused.
>=20
> The whole WBINVD/no-snoop discussion I think is proof of that :\
>=20
> > from iommu p.o.v there is no difference from last one. In v2 the device
> > driver just needs to communicate the PASID virtualization policy at
> > device binding time,
>=20
> I want it documented in the kernel source WTF is happening, because
> otherwise we are going to be completely lost in a few years. And your
> RFC did have device driver specific differences here
>=20
> > > The device knows what it is going to do, we need to convey that to th=
e
> > > IOMMU layer so it is prepared properly.
> >
> > Yes, but it's not necessarily to have iommu fd understand bus specific
> > attributes. In the end when /dev/iommu uAPI calls iommu layer interface=
,
> > it's all bus agnostic.
>=20
> Why not? Just put some inline wrappers to translate the bus specific
> language to your generic language if that is what makes the most
> sense.
>=20

I can do this. Thanks