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Tsirkin" Subject: RE: (proposal) RE: [PATCH v7 00/16] vfio: expose virtual Shared Virtual Addressing to VMs Thread-Topic: (proposal) RE: [PATCH v7 00/16] vfio: expose virtual Shared Virtual Addressing to VMs Thread-Index: AdagceQQLvqwjRCrQOaq1hZ7MgDUUAAt0sKAACmGxcAAPBsbAAAARpcAAAOFkAAAAwCSQADzeAMAAANpJxAAAu+FgAAAOEXwAAlgCoAAABHqwA== Date: Tue, 20 Oct 2020 14:00:31 +0000 Message-ID: References: <45faf89a-0a40-2a7a-0a76-d7ba76d0813b@redhat.com> <9c10b681-dd7e-2e66-d501-7fcc3ff1207a@redhat.com> <21a66a96-4263-7df2-3bec-320e6f38a9de@redhat.com> <6e478a9e-2051-c0cd-b6fd-624ff5ef0f53@redhat.com> <20201020135439.GH6219@nvidia.com> In-Reply-To: <20201020135439.GH6219@nvidia.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: dlp-reaction: no-action dlp-version: 11.5.1.3 dlp-product: dlpe-windows 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: [221.220.190.251] x-ms-publictraffictype: Email x-ms-office365-filtering-correlation-id: 52c13d50-c8c2-4ce2-f6ba-08d87500824b x-ms-traffictypediagnostic: DM6PR11MB4721: 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:4714; x-ms-exchange-senderadcheck: 1 x-microsoft-antispam: BCL:0; x-microsoft-antispam-message-info: WovryCtNoHcrojiTJHJgLqCyRk2i+TSajl6PKFlSR2znxwAwUqLLGfEDIStr08lhg84MZTb9htGmrJmg60CZVsdepKTRiTEMQegWSWJbcrbGtsBNLxMDY9SmErxa3/sH2SDcwDwQHGg+aiGF8FYm7yrpM1nQaQ2HTT/Ur4l2CobbWhuamWvSF6+VdGzKk0UxhVJwq2+0z1jLIoGKKdlIgPC/gKMvSf+bxARGD+8ffmUsmMPkPQA8M2HmO6rN7F6lIv0lPAaDTtpCXf5t8FX3qFFcG9VjNsnZSoZuMDbBgXvIf3eorWKMmUfnlOHrYvj7BvoxTER9R0p44XRsQGCKlw== x-forefront-antispam-report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:DM5PR11MB1435.namprd11.prod.outlook.com;PTR:;CAT:NONE;SFS:(4636009)(39860400002)(366004)(346002)(136003)(396003)(376002)(33656002)(7696005)(86362001)(66556008)(64756008)(76116006)(66476007)(6916009)(2906002)(316002)(7416002)(186003)(26005)(52536014)(5660300002)(478600001)(9686003)(4744005)(55016002)(71200400001)(54906003)(66446008)(66946007)(4326008)(6506007)(8936002)(8676002);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: DM5PR11MB1435.namprd11.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: 52c13d50-c8c2-4ce2-f6ba-08d87500824b X-MS-Exchange-CrossTenant-originalarrivaltime: 20 Oct 2020 14:00:31.7902 (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: NUNCi9Y6KcCuGR5J4slkHJzrXktfgBBsbJ6crFZIS/+snlZJQpFHUYqYVpXNsIegwYThH/+r8RgGoSwJeM3Qog== X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM6PR11MB4721 X-OriginatorOrg: intel.com Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org > From: Jason Gunthorpe > Sent: Tuesday, October 20, 2020 9:55 PM >=20 > On Tue, Oct 20, 2020 at 09:40:14AM +0000, Liu, Yi L wrote: >=20 > > > See previous discussion with Kevin. If I understand correctly, you ex= pect a > shared > > > L2 table if vDPA and VFIO device are using the same PASID. > > > > L2 table sharing is not mandatory. The mapping is the same, but no need= to > > assume L2 tables are shared. Especially for VFIO/vDPA devices. Even wit= hin > > a passthru framework, like VFIO, if the attributes of backend IOMMU are= not > > the same, the L2 page table are not shared, but the mapping is the same= . >=20 > I think not being able to share the PASID shows exactly why this VFIO > centric approach is bad. no, I didn't say PASID is not sharable. My point is sharing L2 page table i= s not mandatory. Regards, Yi Liu > Jason