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Thu, 13 May 2021 18:34:54 +0000 Received: from DM6PR12MB3834.namprd12.prod.outlook.com ([fe80::ddb4:2cbb:4589:f039]) by DM6PR12MB3834.namprd12.prod.outlook.com ([fe80::ddb4:2cbb:4589:f039%4]) with mapi id 15.20.4129.026; Thu, 13 May 2021 18:34:54 +0000 Date: Thu, 13 May 2021 15:34:52 -0300 From: Jason Gunthorpe To: Alex Williamson Cc: Shameerali Kolothum Thodi , liulongfang , "cohuck@redhat.com" , "linux-kernel@vger.kernel.org" , "linuxarm@openeuler.org" Subject: Re: [Linuxarm] Re: [RFC PATCH 2/3] vfio/hisilicon: register the driver to vfio Message-ID: <20210513183452.GP1002214@nvidia.com> References: <25d033e6-1cba-0da0-2ee7-03a14e75b8a5@huawei.com> <20210421121224.62382e5d@redhat.com> <6ea89655-31c5-233b-ca2a-fcc166b5597c@huawei.com> <20210512121053.GT1002214@nvidia.com> <3eaa3114-81b6-1bd9-c7e6-cb1541389b58@huawei.com> <20210513134422.GD1002214@nvidia.com> <20210513110349.68e3d59d@redhat.com> <1035a9a9b03b43dd9f859136ed84a7f8@huawei.com> <20210513122232.589d24d8@redhat.com> Content-Type: text/plain; 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X-MS-Exchange-AntiSpam-MessageData: =?us-ascii?Q?eqcSAQuECtEbaLSAGL2YPHB1sS7ZBHvIokfNZEbOVVxJfH+06nztxYdLZIMJ?= =?us-ascii?Q?T0+muI5m81MzCGNQ5xanpIUOWtUOyFeuuH+wXCADGcqAG8g6eDCEhlZbSyY1?= =?us-ascii?Q?7qdGKYtKeXI9XoN3KcmlxvWvsJg28F1/5G0TE+M9zuxJgh6lWJuBojLfiua6?= =?us-ascii?Q?QfbgX/3VKr4jWspzydjq7YBq4rn1f7U/Vhx8WVTId2bhIEIkZf05c/SNBm6D?= =?us-ascii?Q?QrqO+i3b0FihlAp4gCrbAOWlfBLgWRAXG+UbwO/AfktwSGg7jTmJumxkIPFT?= =?us-ascii?Q?+RZ5wyH5njmzOKYG+5MSMXoVP+swxSg7YUDJPFK/WQJKNvx5oZhgoUDmip3c?= =?us-ascii?Q?MT9OUr6oEiXVmvRJkpAM+g9NeLPU/O23/tjrH8LSWGj3ZAUQxjsOwEWnYUqW?= =?us-ascii?Q?J94oZLMiQ2R5xTM+fUpich04afta3Ni0Va/wRDN1wZmnYqYT/D1ToSxQoaoP?= =?us-ascii?Q?U/eBvvd4fkkja2fHQO1xxYWeXsheguaDr+7Wo8RINHPh9e040MItwxwoqwIP?= =?us-ascii?Q?N60A8wWghsFgzKcU8Xdy7huXM8NF/APyOyEOfFWJhdlWC5cnBMNyxmVlTQ1c?= =?us-ascii?Q?yGQywVa03Q9D4Nxp7Px8FEgxDwW1cuF5xc7xaMYx0+HKUN+MJfj4lWr9uj/2?= =?us-ascii?Q?4DXCtA/jl70QnRFJRaO0dCuyRhoHgkMcWwdQLjhmwqjWGZqRAJAinspPC87H?= =?us-ascii?Q?KNXAndhR2Jskz18nlQ6YbMDCCkDU9UivOjXa3wXMc20ICWGYi7mjuJO8abGu?= =?us-ascii?Q?qgGjp9E/H1zqVJoCzjKGHQEV3cqcL3qaMcIFz7LgppJ5xwFZXM2USOJXFCAf?= =?us-ascii?Q?qM2rjVgvJX1q5hFlC/S9FeXEzfCSHWv398liODHqH8Grx9WmaVIKVtHF5j5/?= =?us-ascii?Q?FzkVMxq6Oe+1WD6C3eKCcduHtRAEgMcJHn0RIb48NcHHsE/TQ6qBq2KxI7wm?= =?us-ascii?Q?Baw0c6/vbQ+n6UBW268xmNGFvUsAP6pad2M3LYYuTnAZv27Gg8Kx5K7kCNk5?= =?us-ascii?Q?Kd4bGhDTMWV/N7DkmzT0ozG3Zo0V+dl3j9d7bKCBV2lUn6Wj2cj5A44egQvD?= =?us-ascii?Q?ZXNwzdamtyJyeJaRw5r5yD3ift6B5DyN8lk5hNk+Pf1BXc8vZnggnaOCN6fN?= =?us-ascii?Q?QnCcoAvTngf1YtIOD/scrXhFVkxljXSVWuxIut38RiYs4oyKGThe7CO1CT2k?= =?us-ascii?Q?EjU1jcZkLNW/X5Jfg2gxpyCA/cZUCp3Fl0srDXJ68Gfw+9PRkeXoAtBNNWUW?= =?us-ascii?Q?fo2cwaag3fQpHd3pjXVaGkYOgAULBvBX+DgRRLiq4hEscEUsYRBwq5CfmQ7C?= =?us-ascii?Q?uR4CkvkRmvUGfHJHASuvppfX?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 7b0c1e23-dac1-41e4-e43f-08d9163dcd11 X-MS-Exchange-CrossTenant-AuthSource: DM6PR12MB3834.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 13 May 2021 18:34:54.0642 (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: Nxihz2Xta9aIFciBR4hzrjHJTlv7e5pXSo1CxSbXNtLRJNzqLYlaTIwP2/s1Pakw X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM5PR12MB1754 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, May 13, 2021 at 12:22:32PM -0600, Alex Williamson wrote: > If you expect this device to appear only as an integrated endpoint, then > I think Jason's suggestion above is correct. Your driver that supports > migration can refuse to load for devices there the topology is other > than expected and you're effectively guaranteeing DMA isolation of the > user and in-kernel drivers by hardware DMA semantics and topology. Some kind of VFIO api 'vfio_is_this_pci_dev_is_safe_to_share()' seems appropriate here. I saw Intel doing the same thing in one of their VDPA driver proposals. Jason