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Tsirkin" Subject: RE: [PATCH v7 00/16] vfio: expose virtual Shared Virtual Addressing to VMs Thread-Topic: [PATCH v7 00/16] vfio: expose virtual Shared Virtual Addressing to VMs Thread-Index: AQHWh19AhgenwZ1qREOwvjqrd6cs+KlnjewAgACZ9oCAAASWAIAAK1qAgAADGwCAAAb/gIAAC9mAgAALxACAAAp5gIAAO0sAgAELFgCAAK+vwA== Date: Wed, 16 Sep 2020 01:19:18 +0000 Message-ID: References: <411c81c0-f13c-37cc-6c26-cafb42b46b15@redhat.com> <20200914133113.GB1375106@myrica> <20200914134738.GX904879@nvidia.com> <20200914162247.GA63399@otc-nc-03> <20200914163354.GG904879@nvidia.com> <20200914105857.3f88a271@x1.home> <20200914174121.GI904879@nvidia.com> <20200914122328.0a262a7b@x1.home> <20200914190057.GM904879@nvidia.com> <20200914163310.450c8d6e@x1.home> <20200915142906.GX904879@nvidia.com> In-Reply-To: <20200915142906.GX904879@nvidia.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: dlp-version: 11.5.1.3 dlp-product: dlpe-windows dlp-reaction: no-action authentication-results: nvidia.com; dkim=none (message not signed) header.d=none;nvidia.com; dmarc=none action=none header.from=intel.com; x-originating-ip: [192.198.147.209] x-ms-publictraffictype: Email x-ms-office365-filtering-correlation-id: bc8e72f3-5b4b-42eb-42be-08d859de891a x-ms-traffictypediagnostic: MWHPR11MB1758: x-ld-processed: 46c98d88-e344-4ed4-8496-4ed7712e255d,ExtAddr x-ms-exchange-transport-forked: True x-microsoft-antispam-prvs: x-ms-oob-tlc-oobclassifiers: OLM:9508; x-ms-exchange-senderadcheck: 1 x-microsoft-antispam: BCL:0; x-microsoft-antispam-message-info: Tfy3f8Jd67SeyAUIs4PigHoMCqWBKAPLtF/g7zXPRsBwwVOG6n0THUo7ZkJbreaEXa9LUcgjhVPVrwDTrG8R55IYt0KmY71EEiVVMpawmHxVip1RrMsVb4cQ96ivsdTEPinwSljP8vY/Bjiemz8uKp0mizp65mU3oY7Ba1Pa4rc9smMTTqzX+8AYwWJ17aLLttkpZiXIONNmdRKgyJ0l//uaDomRWrxYnLHPfFXKTYHVoFF8lvLs19o9mnGJzFhxgzXVM30tPEfo3s2QjR6rFsHA96oAh6Ltmx28PR/jFfgk0Ty5n4CrBVL17J1KHVUBWwLhwSNiKkvN4XalEgM47Q== x-forefront-antispam-report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:MWHPR11MB1645.namprd11.prod.outlook.com;PTR:;CAT:NONE;SFS:(4636009)(376002)(136003)(346002)(396003)(366004)(39860400002)(6506007)(66446008)(64756008)(66556008)(54906003)(8936002)(7696005)(2906002)(316002)(33656002)(8676002)(110136005)(478600001)(86362001)(76116006)(5660300002)(66476007)(71200400001)(7416002)(66946007)(9686003)(55016002)(186003)(52536014)(4326008)(26005);DIR:OUT;SFP:1102; x-ms-exchange-antispam-messagedata: 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 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: MWHPR11MB1645.namprd11.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: bc8e72f3-5b4b-42eb-42be-08d859de891a X-MS-Exchange-CrossTenant-originalarrivaltime: 16 Sep 2020 01:19:18.9257 (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: 5KsMa6zyTQltAgj6CtiH0YYDBJrzpBBbVESsqrISJmSFLMpcBw2qolyRlChtMX37RgusYIkIt3CEJqtn7ekiTg== X-MS-Exchange-Transport-CrossTenantHeadersStamped: MWHPR11MB1758 X-OriginatorOrg: intel.com Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org > From: Jason Gunthorpe > Sent: Tuesday, September 15, 2020 10:29 PM > > > Do they need a device at all? It's not clear to me why RID based > > IOMMU management fits within vfio's scope, but PASID based does not. >=20 > In RID mode vfio-pci completely owns the PCI function, so it is more > natural that VFIO, as the sole device owner, would own the DMA mapping > machinery. Further, the RID IOMMU mode is rarely used outside of VFIO > so there is not much reason to try and disaggregate the API. It is also used by vDPA. >=20 > PASID on the other hand, is shared. vfio-mdev drivers will share the > device with other kernel drivers. PASID and DMA will be concurrent > with VFIO and other kernel drivers/etc. >=20 Looks you are equating PASID to host-side sharing, while ignoring=20 another valid usage that a PASID-capable device is passed through to the guest through vfio-pci and then PASID is used by the guest=20 for guest-side sharing. In such case, it is an exclusive usage in host side and then what is the problem for VFIO to manage PASID given that vfio-pci completely owns the function? Thanks Kevin=20