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Mon, 7 Jun 2021 19:11:28 +0000 Received: from BL0PR12MB5506.namprd12.prod.outlook.com ([fe80::3d51:a3b9:8611:684e]) by BL0PR12MB5506.namprd12.prod.outlook.com ([fe80::3d51:a3b9:8611:684e%6]) with mapi id 15.20.4195.030; Mon, 7 Jun 2021 19:11:28 +0000 Date: Mon, 7 Jun 2021 16:11:26 -0300 From: Jason Gunthorpe To: Dave Jiang Cc: "Tian, Kevin" , Alex Williamson , Cornelia Huck , Kirti Wankhede , "tglx@linutronix.de" , "vkoul@kernel.org" , "Raj, Ashok" , "Dey, Megha" , "Pan, Jacob jun" , "Liu, Yi L" , "Lu, Baolu" , "Kumar, Sanjay K" , "Luck, Tony" , "Williams, Dan J" , "eric.auger@redhat.com" , "pbonzini@redhat.com" , "dmaengine@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "kvm@vger.kernel.org" Subject: Re: [PATCH v6 00/20] Add VFIO mediated device support and DEV-MSI support for the idxd driver Message-ID: <20210607191126.GP1002214@nvidia.com> References: <162164243591.261970.3439987543338120797.stgit@djiang5-desk3.ch.intel.com> <20210523232219.GG1002214@nvidia.com> <86cde154-37c7-c00d-b0c6-06b15b50dbf7@intel.com> <20210602231747.GK1002214@nvidia.com> <20210603014932.GN1002214@nvidia.com> <20210603214009.68fac0c4.alex.williamson@redhat.com> <168ee05a-faf4-3fce-e278-d783104fc442@intel.com> Content-Type: text/plain; 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X-MS-Exchange-AntiSpam-MessageData: =?us-ascii?Q?hZihVjhkVQ0bitXq4J/uLLE4KJ4KVA02jPyDx00eu8ABfl0eQjp27ieT49bp?= =?us-ascii?Q?QjOyse/dGe8Ja7Hc1tm4iE/hGztGGw4T57cA/oRNlUmkIM43APcyt+ypFN0r?= =?us-ascii?Q?ustBphBbJKU0AWsYJbcPGHhHJD68jwsL89BnHSQTFHPjnwtUkKjyUUmBE9+b?= =?us-ascii?Q?avBtmA+j5TwYqHVjbR9qpIku1TNj9yyEcd7P4OJjCFaoAmdbHW8INgILFvG9?= =?us-ascii?Q?OcNMnsCrxFHD9J0tQYqHNvw5E0wKFTJBQK0CwUpsx1EB+zV7tiVj6rpne7vf?= =?us-ascii?Q?zKzYECgphbB8X5+4OyEDWi+2yZRDNwYQJJkyGv67F9dOGI0OEK4KrYx7venN?= =?us-ascii?Q?4hMU0txloCrl53lx0UoqZpdT/4Rfg9hcUO/ve8ApUhC1wFv12nvDghaHgWD3?= =?us-ascii?Q?ahrtD3qLKGHQYLcxS2vT/JzZnOEqgajEzO6ia69kK5jgTIbPDE6TRQTdx+Dk?= =?us-ascii?Q?So2qSap8G4YfCAu2KpW1XOWYxl3eZhEK3gSGYCQhQfb6RUJSo55cZ+88Q1nW?= =?us-ascii?Q?Bhkm4SXL6Sr1nzX5D+NmbaigVX82c7w2uFA5H/bAlnQ1Cq2cJ7s7ItvpukA2?= =?us-ascii?Q?WtKFMaBD5wXNls8zbcmrYzw3aM5wYkOytlarALjCl6V3xFOMK3cpJJL8oE3F?= =?us-ascii?Q?u3F6yvQ/KxjQR89NMVtdfg7yJseWeezBElTUfjv3B8RczKiNA+Uxs2RuMuzP?= =?us-ascii?Q?/eWfX0ihwF7oDIGT0kwVGAMjJrKqt9jhgKFBpmiCyAUYayJfcsefOjJVQNn8?= =?us-ascii?Q?AT3BShnSeZNTka3MA+r7hv4XGZcmfTnQLTzgV9+w8nZpo70TWSUa0C8QuUBT?= =?us-ascii?Q?+VrGqj7bcZm6JR94VKmZ9+efuP/PbQzHiUDkUlzNE9eacnjzB6ob1xUFGtvI?= =?us-ascii?Q?+FfKs8zu/EKNuvVwmFiUtLCnnO2O8kkHPumKQhCmvxCA2ZjwCNwgq2FCfQqz?= =?us-ascii?Q?Ygvprsu4j/PY74AHUNisMx2mLJKz99cMrmP3g6cFhKpGLV/qjphEuIK6bwW9?= =?us-ascii?Q?r23gSdXGvZZx8LccwgnyljsxZsrC5WyTyGT8jIaBb1/Fdlp18rHW2ufSHQoT?= =?us-ascii?Q?HkI+6Xc0xutVUsdHMDHsN4+9WLvmlZoEa7SmlPKKmpcrw5CNtIV2WdXqhuh8?= =?us-ascii?Q?q7l40cgBI/cZ0hHplk23byihKWAH9eiiE4NpsUGl+BIb61a8v3BGr77bxiR5?= =?us-ascii?Q?4xzqb7YQ+SLoU/3intWC+O5UsT071hXvlnvf7rt55//SzDGsA9CJ5i5ghihl?= =?us-ascii?Q?mVqG7Q+Co4djU/dDfpWTUDundLHZj8SIWngTEuePtYpcNIWJ70LcYiF0OpH+?= =?us-ascii?Q?UbI8OYt4DBuDCLhcY/pPL5aN?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 9537196d-fba7-4e77-e8c5-08d929e80cfb X-MS-Exchange-CrossTenant-AuthSource: BL0PR12MB5506.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 07 Jun 2021 19:11:27.8634 (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: 3SI7CCZua7KjmzJhzsazSBp/BJrKp+cBiGWkfH3YXDEuDSqDCdPF5qSRrxMuyiAD X-MS-Exchange-Transport-CrossTenantHeadersStamped: BL1PR12MB5269 Precedence: bulk List-ID: X-Mailing-List: dmaengine@vger.kernel.org On Mon, Jun 07, 2021 at 11:13:04AM -0700, Dave Jiang wrote: > So in step 1, we 'tag' the wq to be dedicated to guest usage and put the > hardware wq into enable state. For a dedicated mode wq, we can definitely > just register directly and skip the mdev step. For a shared wq mode, we can > have multiple mdev running on top of a single wq. So we need some way to > create more mdevs. We can either go with the existing established creation > path by mdev, or invent something custom for the driver as Jason suggested > to accomodate additional virtual devices for guests. We implemented the mdev > path originally with consideration of mdev is established and has a known > interface already. It sounds like you could just as easially have a 'create new vfio' file under the idxd sysfs.. Especially since you already have a bus and dynamic vfio specific things being created on this bus. Have you gone over this with Dan? > I think things become more complicated when we go from a dedicated wq to > shared wq where the relationship of wq : mdev is 1 : 1 goes to 1 : N. Also > needing to keep a consistent user config experience is desired, especially > we already have such behavior since kernel 5.6 for host usages. So we really > need try to avoid doing wq configuration differently just for "mdev" wqs. In > the case suggested above, we basically just flipped the configuration steps. > Mdev is first created through mdev sysfs interface. And then the device > paramters are configured. Where for us, we configure the device parameter > first, and then create the mdev. But in the end, it's still the hybrid mdev > setup right? So you don't even use mdev to configure anything? Yuk. Jason