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X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 04 Oct 2024 20:33:41.0933 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 405f1341-503d-4ea4-ea6d-08dce4b3d57b X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.118.232];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: MWH0EPF000989E8.namprd02.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: BL3PR12MB9052 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20241004_213356_687458_9BC5DA7C X-CRM114-Status: GOOD ( 29.41 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, Oct 04, 2024 at 05:17:46PM -0300, Jason Gunthorpe wrote: > On Fri, Oct 04, 2024 at 12:25:19PM -0700, Nicolin Chen wrote: > > > With that, I wonder what is better for the initial version of > > this structure, a generic virtual ID or a driver-named ID like > > "Stream ID"? The latter might be more understandable/flexible, > > so we won't need to justify a generic virtual ID along the way > > if something changes in the nature? > > I think the name could be a bit more specific "viommu_device_id" > maybe? And elaborate in the kdoc that this is about the identifier > that the iommu HW itself uses. A "vIOMMU Device ID" might sound a bit confusing with an ID of a vIOMMU itself :-/ At this moment, I named it "virt_id" in uAPI with a description: " * @virt_id: Virtual device ID per vIOMMU" I could add to that (or just in the documentation): "e.g. ARM's Stream ID, AMD's DeviceID, Intel's Context Table ID" to clarify it further. > > That sounds wider than what I defined it for in my patch: > > * struct iommu_vdevice_alloc - ioctl(IOMMU_VDEVICE_ALLOC) > > * ... > > * Allocate a virtual device instance (for a physical device) against a vIOMMU. > > * This instance holds the device's information in a VM, related to its vIOMMU. > > > > Would you please help rephrase it? It'd be also helpful for me > > to update the doc. > > I think that is still OK for the moment. > > > Though I feel slightly odd if we define it wider than "vIOMMU" > > since this is an iommufd header... > > The notion I have is that vIOMMU would expand to encompass not just > the physical hypervisor controled vIOMMU but also the vIOMMU > controlled by the trusted "lowervisor" in a pkvm/cc/whatever world. > > Alexey is working on vIOMMU support in CC which has the trusted world > do some of the trusted vIOMMU components. I'm hoping the other people > in this area will look at his design and make it fit nicely to > everyone. Oh, I didn't connect the dots that lowervisor must rely on the vIOMMU too -- I'd need to check the CC stuff in detail. In that case, having it in vIOMMU uAPI totally makes sense. Thanks Nicolin