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Tue, 29 Apr 2025 11:15:02 -0700 Date: Tue, 29 Apr 2025 11:15:00 -0700 From: Nicolin Chen To: Pranjal Shrivastava CC: , , , , , , , , , , , , , , , , , , , , , , , , , , Subject: Re: [PATCH v2 10/22] iommufd/viommmu: Add IOMMUFD_CMD_VCMDQ_ALLOC ioctl Message-ID: References: <094992b874190ffdcf6012104b419c8649b5e4b4.1745646960.git.nicolinc@nvidia.com> Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: X-NV-OnPremToCloud: AnonymousSubmission X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CH2PEPF0000009A:EE_|SA1PR12MB7128:EE_ X-MS-Office365-Filtering-Correlation-Id: a674492f-654b-4d77-92ef-08dd8749cb5e X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|36860700013|82310400026|7416014|376014; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?i47DZKPnZvI/KB+eNLyVsx6DYkeieEGt7G3z8pL0N/lsj6S4yRvhxqwjyWBo?= =?us-ascii?Q?9oOTAFK2D30mDayKNrCBtI+xND7nWjGd/qmhZD5F24bSsPwefqtnoboR5Whz?= =?us-ascii?Q?s1CL5wEfv63oo+lcCWUylhFi7ClcT5uB5nm1Z8+xk+t0qLKl7RDv0v3xmtf0?= =?us-ascii?Q?gk7JgpaFndQOjbxUT92W4LM3nvuGzoRcxFyDPzdwnyP7CxjoA+gcGv7K0Rf4?= =?us-ascii?Q?T7G3P2wWm5FjG6trRvaa6VOsXCfyMR+1IzyVSDPHmUSYa95rKPf7ihWBbReL?= =?us-ascii?Q?P8dzlp6NzrlHK6XiUCUHWqUqXJzPt0bd18MSkEyFofc+dMpN5dwh0H/B7RNu?= =?us-ascii?Q?foEva7R0rhzjlHEkCvjB2RE8eVlEyvw8vDO0ozwTKD0niWcE7eoEZiudZ1Sd?= =?us-ascii?Q?8XNUK7+v7IuXKH0A8QyLYayNzyg2WiJbFzIzyjQqI6APEsTTWCzOqJqamHq9?= =?us-ascii?Q?y3EOqbQfn+tIPh7l7e5ZijYOK20vzpcHizsUtqZmxChGU2RhBQyprxCF9KWz?= =?us-ascii?Q?tSz5krPnBF+lx1Y0mzNmpnsTBF0aSKdSxLByNP6EvmiboYCdMVzTA3It+sIy?= =?us-ascii?Q?ginMdShKNS7Qs/mHrDHcEvSzEl0eFSZ7/0pZiM0kB8T9nXHCOKk+MdxIAZJV?= =?us-ascii?Q?IAV5wDuFd4/B7Q0F/sUgIY7DGm3/Bvti6ebnmqLfcVj4YLEfAzaccXQu2qEF?= =?us-ascii?Q?tbbA1irt2tJvvXnxhN4lvLQY37OLSNIHj6CQYEjJmf28Wm6VeuLhoSQiuKph?= =?us-ascii?Q?kLDn3TOaDmomVHRoiGyYR3RYfXC7cbYgv6kmw2rZN11yDcBGLwG7ezjSmZYD?= =?us-ascii?Q?2WLc8teaZlXKWBlIbyjheEmcl07jDct6mEU0V/D6fmtkVKXt7h5USKFqIuHc?= =?us-ascii?Q?3J1sxvltePUOcmHbcFtuX06AvEtlKezye2nnayS6HDzPoxmAda6pk4TwjfxG?= =?us-ascii?Q?rMCSQzAwe7GGTbdfF1Yk3iiv1UW3AIG69GUAp1M084esS7rj1gmGNeEdofoA?= =?us-ascii?Q?7VnFrsNcKw+MiR4ouhMR3ZWOgBNxsNShPjalpH9d/k0LHNZWOGUtSmK7EVEi?= =?us-ascii?Q?SiRGNo93CrzoiEhX/xqwxWl0Ih2rkzOF1ea3wCd/X9/QZwBO4mwo+CXG/iac?= =?us-ascii?Q?BCMvf/HLE6ejuXz5RHPyCWYG/A5ialNZokG1QdV4dW9MO/ovrYe0y+UC4Wbz?= =?us-ascii?Q?ggUtr/dyWMydTMLgeENDnUQxXR2tJUZbTscbquxN39gliSjrf2jiC6d/V/Q4?= =?us-ascii?Q?JahSBLXC5mx+O0TTjRHGPx/wKsBQV1hJbEh7faykTyRUerI/WCQcLmJfDezP?= =?us-ascii?Q?nmUf2avQeCdQAQXyUYNYBcvonv+WMteGXZ4+vCsnJg/TZU3m4wVLAfHb28LA?= =?us-ascii?Q?9b84h/x40khRCL/mfoFxH/r/AvFpp62PRBPmhZpituGGbHV8X0dUstUsRat8?= =?us-ascii?Q?/2QGqSYo/dytFrX4UgYxJhzSnU/MzZpDMX3ONYdiIUZbmskNOg1GoOL7EITG?= =?us-ascii?Q?ke3VxSML2yuY/kPnzTPopVF71rWFg8kpFEV4?= X-Forefront-Antispam-Report: CIP:216.228.118.232;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:mail.nvidia.com;PTR:dc7edge1.nvidia.com;CAT:NONE;SFS:(13230040)(1800799024)(36860700013)(82310400026)(7416014)(376014);DIR:OUT;SFP:1101; X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 29 Apr 2025 18:15:16.9249 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: a674492f-654b-4d77-92ef-08dd8749cb5e 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: CH2PEPF0000009A.namprd02.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: SA1PR12MB7128 On Tue, Apr 29, 2025 at 06:10:31PM +0000, Pranjal Shrivastava wrote: > On Tue, Apr 29, 2025 at 08:28:01AM +0000, Pranjal Shrivastava wrote: > > On Mon, Apr 28, 2025 at 03:44:08PM -0700, Nicolin Chen wrote: > > > On Mon, Apr 28, 2025 at 09:34:05PM +0000, Pranjal Shrivastava wrote: > > > > On Fri, Apr 25, 2025 at 10:58:05PM -0700, Nicolin Chen wrote: > > [...] > > > > IIUC, one vintf can have multiple lvcmdqs and looking at the series > > > > it looks like the vcmdq_alloc allocates a single lvcmdq. Is the plan to > > > > dedicate one lvcmdq to per VM? Which means VMs can share a vintf? > > > > > > VINTF is a vSMMU instance per SMMU. Each VINTF can have multiple > > > LVCMDQs. Each vCMDQ is allocated per IOMMUFD_CMD_VCMDQ_ALLOC. In > > > other word, VM can issue multiple IOMMUFD_CMD_VCMDQ_ALLOC calls > > > for each VTINF/vSMMU. > > > > > > > Ack. I'm just wondering why would a single VM want more than one vCMDQ > > per vSMMU? > > [...] > > I guess the only thing on this patch from me was to understand why > would a single VM want more than one vCMDQ per vSMMU? (Just curious to > know :) ) It gives some perf gain since it has two portals to fill commands. Nicolin