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;
Date:   Tue, 15 Mar 2022 11:38:58 -0300
From:   Jason Gunthorpe <jgg@nvidia.com>
To:     Matthew Rosato <mjrosato@linux.ibm.com>
Cc:     linux-s390@vger.kernel.org, alex.williamson@redhat.com,
        cohuck@redhat.com, schnelle@linux.ibm.com, farman@linux.ibm.com,
        pmorel@linux.ibm.com, borntraeger@linux.ibm.com, hca@linux.ibm.com,
        gor@linux.ibm.com, gerald.schaefer@linux.ibm.com,
        agordeev@linux.ibm.com, svens@linux.ibm.com, frankja@linux.ibm.com,
        david@redhat.com, imbrenda@linux.ibm.com, vneethv@linux.ibm.com,
        oberpar@linux.ibm.com, freude@linux.ibm.com, thuth@redhat.com,
        pasic@linux.ibm.com, joro@8bytes.org, will@kernel.org,
        pbonzini@redhat.com, corbet@lwn.net, kvm@vger.kernel.org,
        linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org,
        linux-doc@vger.kernel.org
Subject: Re: [PATCH v4 15/32] vfio: introduce KVM-owned IOMMU type
Message-ID: <20220315143858.GY11336@nvidia.com>
References: <20220314194451.58266-1-mjrosato@linux.ibm.com>
 <20220314194451.58266-16-mjrosato@linux.ibm.com>
 <20220314213808.GI11336@nvidia.com>
 <decc5320-eb3e-af25-fd2b-77fabe56a897@linux.ibm.com>
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <decc5320-eb3e-af25-fd2b-77fabe56a897@linux.ibm.com>
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?ZNLFrO4VZZiZnzRqMEriaQCQIwFsShbrrMr2FQ+QwC42avm2YXWCLmMnvLO4?=
 =?us-ascii?Q?I4YV/MapRxCqE2OfD00jSNTt8Y8FdlTsvU2G0xbiEw+s3gOF2Ewvd0nnG8tk?=
 =?us-ascii?Q?P/iAt2z6Go9shug1/nZUI9mEWJH3U9e0y7rjHuCzOu3eu7QLDdv/p+cmVeDu?=
 =?us-ascii?Q?pSqqd0kMjLwTiazLft7Zx74H/54fMj/NEIN14mmwB7GRnXLvshDH6m0vQB5D?=
 =?us-ascii?Q?hy6gRmCxTBafwyivABwp2E+PMAg5qmvd6g83g5wd/iWWFswOHB9uJ5vRNRgb?=
 =?us-ascii?Q?7LaaXDv6x0qMyYHly3kyKzkOBX8tkbIH3b92cz9mA+ZtXO+NBVkSANfstXi6?=
 =?us-ascii?Q?z81kh9VRUx3UcZ2T+Rf5f6CZrQMA+MOpLH9zTCCieUPgPYlKGFCpz6uFwACu?=
 =?us-ascii?Q?dTBjRRb5Aa9RybzR/JCUeXwF6eKtD6+SJx2dDG089BpQJNNITkTmxVfX7rY3?=
 =?us-ascii?Q?Q4IU6Od5WDFMGg5RIkyMUeSwW/AZ1NX4M+TGiwP2rsyvuXWdTeCosWfWpIxd?=
 =?us-ascii?Q?XJjr8g63aXFsmt9vzq6if8Ojp3xjmHRVsoEQAwNtMps+6zWfDBxL1RHWwreC?=
 =?us-ascii?Q?+PN798LV5Eq85gB4kL/ER2Z4Zz0k228ygx6HJVNoqYmYSbNGVvXwvLX2+IIz?=
 =?us-ascii?Q?x9pkDkLzqrswuW29jGnL6MweTHqeRJ0yIRhyy4NO4Pu/BGcWfO32QazkPcWe?=
 =?us-ascii?Q?U317Y/bETESCXxEEWPCI1ADZiFSWFXBtOWLTgbz36hGX7NI7c3WxqdC51jeh?=
 =?us-ascii?Q?mTEOd5AFDM0R3F2KicfSdvwJ180LyYDHCSaVZ/DlWAf4A5wiu0TEfV1tnQPk?=
 =?us-ascii?Q?K/wMMp29ba5oGDN1wWV/i19Tmb2IO5AyXdXDJZIT/kVOnwkpLDutjrLCkz7j?=
 =?us-ascii?Q?aiS3dRe9rrxNXS4Q3I3GudnyjvxNM/2SD8gZzjh7RldtxJuf+id1nsqQ2nG1?=
 =?us-ascii?Q?fPX/LMq3Y8DVx6VQQDtMRdLj/txs82DYmMkHujc5PwxpCDmP9aCtI8YZ5m7I?=
 =?us-ascii?Q?yzafZYh0YWCg9D1r2++XxWoeN55aNOs3d2N+FKmYoCo4LnQO8VvHOfsRa+tO?=
 =?us-ascii?Q?iyOFnZevIYhPXSnElbbUDMDOpb8qeq9ZRjbxIZ6NqOJ1ydLrWN+NXTodxga3?=
 =?us-ascii?Q?bKJIm4+/Ubdv3k84Ss5E/1CAdujC2IOqj4xnhJzp4EKj6UqWRzn50F8BsT60?=
 =?us-ascii?Q?CkyhaxSujF7yPhcqtnHVXlQeDnw0hi+qvRtyYFaieLPwPSu9MGgrUXDsZYLJ?=
 =?us-ascii?Q?ER3bk6RFWHpexqQ2QFuuwQvCBVE/3bQEy/F2AMJL3X/jG2GW9dN8GsoaF6Yp?=
 =?us-ascii?Q?C1YIN4YPF9EvCK94de2QeqyGNJBpQDasRWcl7S5axUum+geLY3FWq8GkMuMX?=
 =?us-ascii?Q?dYldXJzSZvIBeFT6UlhCTuWSYqDalQS83wFWX0+plmuJuPYTmAB2x5pSdZ/I?=
 =?us-ascii?Q?7keL4A8AXrtsADF9keOO811Th2D43+IB?=
X-OriginatorOrg: Nvidia.com
X-MS-Exchange-CrossTenant-Network-Message-Id: 4d9ae89f-bf99-4c95-6f1b-08da06918aa4
X-MS-Exchange-CrossTenant-AuthSource: MN2PR12MB4192.namprd12.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 15 Mar 2022 14:38:59.4747
 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a
X-MS-Exchange-CrossTenant-MailboxType: HOSTED
X-MS-Exchange-CrossTenant-UserPrincipalName: 6kFSrRY+UxUMTcejoABIPYTfYn6CpAIysUNDgs2aEqjfpi949C4Yn8YboPDxVSrC
X-MS-Exchange-Transport-CrossTenantHeadersStamped: MN2PR12MB2957
X-Spam-Status: No, score=-2.6 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH,
        DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FORGED_SPF_HELO,
        RCVD_IN_DNSWL_NONE,RCVD_IN_MSPIKE_H2,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

On Tue, Mar 15, 2022 at 09:49:01AM -0400, Matthew Rosato wrote:

> The rationale for splitting steps 1 and 2 are that VFIO_SET_IOMMU doesn't
> have a mechanism for specifying more than the type as an arg, no?  Otherwise
> yes, you could specify a kvm fd at this point and it would have some other
> advantages (e.g. skip notifier).  But we still can't use the IOMMU for
> mapping until step 3.

Stuff like this is why I'd be much happier if this could join our
iommfd project so we can have clean modeling of the multiple iommu_domains.

Jason