Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
From:   "Tian, Kevin" <kevin.tian@intel.com>
To:     Jacob Pan <jacob.jun.pan@linux.intel.com>
CC:     LKML <linux-kernel@vger.kernel.org>,
        "iommu@lists.linux.dev" <iommu@lists.linux.dev>,
        Robin Murphy <robin.murphy@arm.com>,
        Jason Gunthorpe <jgg@nvidia.com>,
        Lu Baolu <baolu.lu@linux.intel.com>,
        Joerg Roedel <joro@8bytes.org>,
        "dmaengine@vger.kernel.org" <dmaengine@vger.kernel.org>,
        "vkoul@kernel.org" <vkoul@kernel.org>,
        Will Deacon <will@kernel.org>,
        "David Woodhouse" <dwmw2@infradead.org>,
        "Raj, Ashok" <ashok.raj@intel.com>,
        "Liu, Yi L" <yi.l.liu@intel.com>,
        "Yu, Fenghua" <fenghua.yu@intel.com>,
        "Jiang, Dave" <dave.jiang@intel.com>,
        "Luck, Tony" <tony.luck@intel.com>,
        "Zanussi, Tom" <tom.zanussi@intel.com>,
        "Ranganathan, Narayan" <narayan.ranganathan@intel.com>
Subject: RE: [PATCH v5 1/7] iommu: Generalize default PCIe requester ID PASID
Thread-Topic: [PATCH v5 1/7] iommu: Generalize default PCIe requester ID PASID
Thread-Index: AQHZeTASrtonzxFRJk+i3Dzn6cfwy69Ad3fggABqFYCACoJxgA==
Date:   Fri, 5 May 2023 08:28:13 +0000
Message-ID: <BN9PR11MB5276A1CC0B5FF8D9394F22F98C729@BN9PR11MB5276.namprd11.prod.outlook.com>
References: <20230427174937.471668-1-jacob.jun.pan@linux.intel.com>
        <20230427174937.471668-2-jacob.jun.pan@linux.intel.com>
        <BN9PR11MB5276FD027EC3D6BAA24046F58C6B9@BN9PR11MB5276.namprd11.prod.outlook.com>
 <20230428085615.58e437c9@jacob-builder>
In-Reply-To: <20230428085615.58e437c9@jacob-builder>
Accept-Language: en-US
Content-Language: en-US
x-ms-exchange-antispam-messagedata-chunkcount: 1
x-ms-exchange-antispam-messagedata-0: =?us-ascii?Q?ky2qG/2ZbsX9chtUKcGTzB3hevOLcIBA3rqGQddrtFxI0WPKavZozsi4K6Fu?=
 =?us-ascii?Q?8jGJ7PeDieiFwtdZPWS3+ITbbOe2ddOfUu2Cm1i4mDMFdduARVzjAQsPX5cu?=
 =?us-ascii?Q?jog0yLdl1tEEUjs1uu9rcfrOwQxg6gN2OjeEaycOK5y9dsJStBvnjNaLX8w2?=
 =?us-ascii?Q?c4PBVz8cvM91QLGyRD3dwUPQ/iuZW87xH2iP9Vs7iPazr5J6lINe6eOyaI4p?=
 =?us-ascii?Q?k8VHq/nbq5JJZUkX9vhE7MmQnE5T1X6FPALlFbJ+4qAElLPnrL1t97Mxf8xe?=
 =?us-ascii?Q?lqQCusRXZDlhpohZq0vxJnKX5tZ24bAmulV3pfHfpgQM5G8TZpP/ENJ1oeXT?=
 =?us-ascii?Q?egciNMfJtJz+p+bUIKrKeC3S0trLuddY+JpAaoYHYeW54EcfYoN7bN/AuT84?=
 =?us-ascii?Q?R5npmr9RMubZ6wRfok3bu4v2QpLKlUoklRAm5l/BJx2W9DMW8DGqwJF1TDc6?=
 =?us-ascii?Q?5ZBWJ3cTXZnTu81TD9D2/Ij8dDMhGC1LscfaG7Cd8F7KUk85KvFky2thb/ID?=
 =?us-ascii?Q?1ZVQgtwwEtETMNOwq0/9xUx/X6s/M9gY/8dQC57FehfUySL8IcuXLMqYLLAo?=
 =?us-ascii?Q?wX3iR2TVBb/e20UCaYnFbx0s6pmmriZS2vA6v4Dnm9FNTadx7E70hE3Py3dZ?=
 =?us-ascii?Q?J4JJLqxOBjt6Pz9It6u2mrYljPnTmBrJUO1v5BoEaMv2cPQlOujtIRbw24o6?=
 =?us-ascii?Q?jDHBf9SbbSdd2buAXQZgcABQTUcnmEfjJxE28XICHhfFjnuFh+9G9A9Y2QUX?=
 =?us-ascii?Q?tg1ONHN9q+iB4M7mOOsbC123Ae43LFbNpL2mImt2NR99Ppj/TiqrJ5+d4Wb6?=
 =?us-ascii?Q?B+sjy/ygQtKIrMrjT86SkDZ/Jf0LCp1NyVPdD8nfAkqPSn1EhAQ8hPntDbxS?=
 =?us-ascii?Q?wMfWkUVixQ01965YxlPB+jfhZ3kBdnqVKBl1VoBIX13xZpewiEFoxHRlt/uP?=
 =?us-ascii?Q?3YWABhOZs4aLFM6A62SnS694o3j5X/dh5mA+QgIpK5OtIk6JMz5ojlC4O5gW?=
 =?us-ascii?Q?UhnpphJvYuNJT1S4rE0hvb05B7lWM5bMnvhVNMPyWJDARydZ08fGP0FJcLVb?=
 =?us-ascii?Q?riz+5uTOeFlcBWT5WrEVd/VPyxq8PGnJgYwHndWQf9cVXEdVOS/loTxxI3Mo?=
 =?us-ascii?Q?6iFROzhBLpAUevrx8PwsUDfvfUL5Th5WMpoKXbJeHd9rJJXOaEbm3NI+DXwv?=
 =?us-ascii?Q?INcHafJlitBOLQTDLNUtJhi9Y/1wTTai4xRC27EcxECVh6/0TdyZEGZwlgun?=
 =?us-ascii?Q?xqkZifT5NLsl8JSKKyplO0roV03zSiXMxgZujAI3xHYSyo12Gd4ExwKWwgfj?=
 =?us-ascii?Q?ALBic6qHX06vfrngCVFdeq7Oj9b+Ss7QLmVZMLLYoUunEDUVvWzFoj9OlIMU?=
 =?us-ascii?Q?DINiI3Lsy+spqsA4Ba5fzrbrLqyhNEO9eDT2liSCzY0zGl8DlFCyRBffWKrP?=
 =?us-ascii?Q?KPZu0uiyFS2qQT2RLaL5nf9X94ib1Ucv6GCaZjWtG+oOfdlWi+pUZI02dv1o?=
 =?us-ascii?Q?l6ij/OqFhzQtzQOhUcLo8P0k8vm3Zi31/eT5egogkmTfRt4niNGDmHB9tQ?=
 =?us-ascii?Q?=3D=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: BN9PR11MB5276.namprd11.prod.outlook.com
X-MS-Exchange-CrossTenant-Network-Message-Id: ebd51753-7079-48c4-f20d-08db4d42aacf
X-MS-Exchange-CrossTenant-originalarrivaltime: 05 May 2023 08:28:13.1358
 (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: grYdsUaupIYZkAa0DsvZvA2hPLVPXTaIgW0u/mnx5BN3U/+KSGgLSSYS0hueNq6kYFB6nN2q5HTZl0RvL8HBiA==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: LV8PR11MB8584
X-OriginatorOrg: intel.com
X-Spam-Status: No, score=-4.6 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH,
        DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_MED,
        SPF_HELO_PASS,SPF_NONE,T_SCC_BODY_TEXT_LINE autolearn=ham
        autolearn_force=no version=3.4.6
X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on
        lindbergh.monkeyblade.net
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

> From: Jacob Pan <jacob.jun.pan@linux.intel.com>
> Sent: Friday, April 28, 2023 11:56 PM
>=20
> Hi Kevin,
>=20
> On Fri, 28 Apr 2023 09:38:32 +0000, "Tian, Kevin" <kevin.tian@intel.com>
> wrote:
>=20
> > > From: Jacob Pan <jacob.jun.pan@linux.intel.com>
> > > Sent: Friday, April 28, 2023 1:50 AM
> > >
> > > PCIe Process address space ID (PASID) is used to tag DMA traffic, it
> > > provides finer grained isolation than requester ID (RID).
> > >
> > > For each RID, 0 is as a special PASID for the legacy DMA (without
> > > PASID), thus RID_PASID. This is universal across all architectures,
> > > therefore warranted to be declared in the common header.
> > > Noting that VT-d could support none-zero RID_PASID, but currently not
> > > used.
> > >
> > > By having a common RID_PASID, we can avoid conflicts between differen=
t
> > > use cases in the generic code. e.g. SVA and DMA API with PASIDs.
> >
> > You intend it to be generic but in the end only vt-d driver is changed
> > to use it in this series...
> change for SVA is in the patch.

My point was that since it is common why there is no change in arm-smmu
driver to use the common macro?

>=20
> > > @@ -190,6 +190,7 @@ enum iommu_dev_features {
> > >  	IOMMU_DEV_FEAT_IOPF,
> > >  };
> > >
> > > +#define IOMMU_DEF_RID_PASID	(0U) /* Reserved for DMA w/o PASID
> > > */
> >
> > Is RID a general team on other platform?
> RID, aka  requester id is a PCI term. so I this it is common though on SM=
MU
> might be better called stream ID PASID?
>=20
> > Would IOMMU_DEF_NO_PASID serve the purpose better?
> not sure, it is still a PASID. For completeness, might be called
> IOMMU_DEF_PASID_FOR_DMA_NO_PASID :)
>=20
> other suggestions?
>=20

that is even worse. Let's keep the original one and see whether others
have better suggestion.