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: O7mU1WPHV18KIvd3ExD43188IJsn6GotZyR5eVnvXgvG8Q0SJ/B4E5e80IA45TKPJeDMTWgpz6
 kB0+R31Q5awQ==
IronPort-SDR: WW0w83WPN19IN26T9VrSiMNvi7VF22fgH2DRQcxLamAycMyhGsGbmZHinw6q2LJ7WXqFp8HtiS
 /OaP/EuQMl5g==
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: AddSzQ97BhCb3gd8AUyldaDZ6yOMNABTUTCAAQiuDaAADwOFgAJSmyVg
Date:   Tue, 15 Jun 2021 08:59:25 +0000
Message-ID: <MWHPR11MB1886BA2258AFD92D5249AC488C309@MWHPR11MB1886.namprd11.prod.outlook.com>
References: <MWHPR11MB1886422D4839B372C6AB245F8C239@MWHPR11MB1886.namprd11.prod.outlook.com>
 <20210528233649.GB3816344@nvidia.com>
 <MWHPR11MB188621A9D1181A414D5491198C3C9@MWHPR11MB1886.namprd11.prod.outlook.com>
 <20210603130519.GY1002214@nvidia.com>
In-Reply-To: <20210603130519.GY1002214@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?mtsxsaIroVwwMjeqfTkEvrmsbiYu362WbAaYdQeHoCgmYkYFQ+HyRUQPo7cV?=
 =?us-ascii?Q?lyCZTEfmEjVHj5UhnT/btMtkhfW/6SOMqI9sgTkWWITj/J578uJrGHiyStUD?=
 =?us-ascii?Q?aiAss1HEqyZ/EmtQhwv+CWEDlst7zAb4/Mppa/mwMv9Kh99JnTiyFZChLx3v?=
 =?us-ascii?Q?63CSOWvQDVUX2y3wM/fgZvoP4RPcPlWxkicDWidA+BtD9tCyy52xQ7xuM0ly?=
 =?us-ascii?Q?stDxBw8m+2rCR4p1QqB6kqkk/LCp2o5vrI2djHeh0f5R/GJdn6S9R4aiXSdh?=
 =?us-ascii?Q?NRnfl9aNZ+HrLESOctS1YG/3+LgviTdbN9tPkXoQxz7ZZUd6qLpmk/iWBRLd?=
 =?us-ascii?Q?uzkQJMLeeaXT3AIiDNP/IveXxh8qUHb8Z7ILtgyuSJXfMLfd6grgauSasWwd?=
 =?us-ascii?Q?/R8T+HIHh5c56yhyU4CkMl7Rmx/U5nBkGA6u2ERjGcTr8PEshfnHwywSLX5z?=
 =?us-ascii?Q?7HYAD09fdK6zTnKnQo4sbMwpuyy8EybXJ3LXqmMISigSSwMuFK/MR19sEvyy?=
 =?us-ascii?Q?JMnyzEWo7DFtLhh8clvxQEQOGzqfAWdG+/hdMkoFW7nxcncB/DOZHGjfsxmb?=
 =?us-ascii?Q?ppkLXCNBap7KisyYNtMAn14sp85wbIs93moymgnMGqWNZQ1lWsGKb2JtDnkE?=
 =?us-ascii?Q?sinGeNqeHUHysFmUoHUhKh8IXsHsvRt9kY3I8evv4PGnhaYWBDdgBobsnk51?=
 =?us-ascii?Q?py1J6fBMx+IqLa6jbQlKrgLCmlPSBwNdMnqBobe/gTVuZtRGkLQTBJj5C4Zw?=
 =?us-ascii?Q?qXREZdP1tluYkZBvyonOw1cnRSeBIJu7YiDcaWQGWZi7o/0iJH9Uz5xhRjHg?=
 =?us-ascii?Q?dMJKOhH9Q5z9k7kEqJsd80rRnG/koWluxjae0bSZ+rwI+gwUgpQykNlBmFnE?=
 =?us-ascii?Q?wKqdzqvmRv99WUyXqaFval1t6meZteW3Rx2QAKdsrBmw+fj0PMob8xKXJIus?=
 =?us-ascii?Q?F41GBUrfNK1bseYN27gb5LVfJalx1gBjxwSX8a2h/vzdvJyQC+Y0weHQ/J3B?=
 =?us-ascii?Q?ANbukoAhs/CfePYZbdALjcbPg45v4d39/VRx6uMDtDcZh25vOKdiWF1SfyCC?=
 =?us-ascii?Q?O4elHq7yFtVE25c+rY0DJrQahaUm87QjVi7Nz3WWBwl5EYDT/AFL6y892j41?=
 =?us-ascii?Q?eetEamkLuy+5pgCpqSmXm0Z6QXqs6qA/uaf1hWCTm/iUcsan2iLdCo16Rbr5?=
 =?us-ascii?Q?GAXNZkTeeAoFCKjC76S1+SDRw0fNp5ZLFvsFm1GICyH63GEluPanbFa/nCS5?=
 =?us-ascii?Q?UaNQFCzvK4igFV9wK861rJetFDmDobVAALkeNDJgXgo84lngpAp65gDQmROG?=
 =?us-ascii?Q?U4gx8OjFgJ6eWzorpbj24vtT?=
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: 6b2f7679-526f-4b1f-9698-08d92fdbe06b
X-MS-Exchange-CrossTenant-originalarrivaltime: 15 Jun 2021 08:59:25.8216
 (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: fEZQmNLEefx1A+piSgBiVRK8u9tfclOinJ328f7pP75hla0DSWlcfPjYEL14y0H1UnKQuofo24LGuJLpQr5Iqw==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: CO1PR11MB5153
X-OriginatorOrg: intel.com
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

Hi, Jason,

> From: Jason Gunthorpe
> Sent: Thursday, June 3, 2021 9:05 PM
>=20
> On Thu, Jun 03, 2021 at 06:39:30AM +0000, Tian, Kevin wrote:
> > > > Two helper functions are provided to support VFIO_ATTACH_IOASID:
> > > >
> > > > 	struct attach_info {
> > > > 		u32	ioasid;
> > > > 		// If valid, the PASID to be used physically
> > > > 		u32	pasid;
> > > > 	};
> > > > 	int ioasid_device_attach(struct ioasid_dev *dev,
> > > > 		struct attach_info info);
> > > > 	int ioasid_device_detach(struct ioasid_dev *dev, u32 ioasid);
> > >
> > > Honestly, I still prefer this to be highly explicit as this is where
> > > all device driver authors get invovled:
> > >
> > > ioasid_pci_device_attach(struct pci_device *pdev, struct ioasid_dev *=
dev,
> > > u32 ioasid);
> > > ioasid_pci_device_pasid_attach(struct pci_device *pdev, u32
> *physical_pasid,
> > > struct ioasid_dev *dev, u32 ioasid);
> >
> > Then better naming it as pci_device_attach_ioasid since the 1st paramet=
er
> > is struct pci_device?
>=20
> No, the leading tag indicates the API's primary subystem, in this case
> it is iommu (and if you prefer list the iommu related arguments first)
>=20

I have a question on this suggestion when working on v2.

Within IOMMU fd it uses only the generic struct device pointer, which
is already saved in struct ioasid_dev at device bind time:

	struct ioasid_dev *ioasid_register_device(struct ioasid_ctx *ctx,
		struct device *device, u64 device_label);

What does this additional struct pci_device bring when it's specified in
the attach call? If we save it in attach_data, at which point will it be
used or checked?=20

Can you help elaborate?

Thanks
Kevin