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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?PvZn1M8/EZ86qhNovOg6MQsEuRU5WN7kMXZM549edUAmftk4SFUZwSzXd5O3?= =?us-ascii?Q?YbejgK9pkIVZkmlNTtRNSp/ddUBBj7TFbG6pHx+4IwNS+ICrILOihFQ/oG+N?= =?us-ascii?Q?rWS1U+t+DMGwUTPFSeoqqoyFCssZMPoZgKM/laevI9PHT6s9990UY8CejoWd?= =?us-ascii?Q?+fWCOPXZAFi12JFzuJYYJi0P93P0h9uKdqrPlZejsPOyyD2dhUmW6zHs8ygt?= =?us-ascii?Q?/NK9aeQ8ZGKZrnL5/43EZ5lId8fz4I5HNCZQ+PX+RFjCyT+OQo9S6pWjRpm7?= =?us-ascii?Q?R5bItNTAXmXlQeG1NqwCPdYEfolL3WpdocoIUTGdAgw5u5Ju7iN7XOFX9t2Q?= =?us-ascii?Q?8kLWwwBVxd1y4V32FIyEI+fr9ie8QrlLVsq3iMQ3jrA2OT/LOj2QnIIvHX0s?= =?us-ascii?Q?6Owyo2no9FQTTNUVXf8LuuTaAPik3Qzaq7pJ/Oqwg8CKTA86Ymw44aeyGCEZ?= =?us-ascii?Q?6f2nZX9F3cyj+P0hBxmZLFrwfX5gEI/aVBNVlwE6/MGlihlSa/lJTkyWs+am?= =?us-ascii?Q?lbnoym+sAwFz/+GW3V2apbFWkhqn79ylZTllqKV8qKUvsCRmibmttkHGT4Xy?= =?us-ascii?Q?MIOJkyN8sx8S8ULkTZI07YJ9BH8cR5afafzU+sXbMs1BSQ3xW/YPtAvEHHID?= =?us-ascii?Q?qbBfek9atMIvmWAyV87dfM4JW6w8z95mF/lHOiQnDAG6Zxt0lXd2y+wo49Nv?= =?us-ascii?Q?pBX7pMYrHznPgA8nWJceejmcX5tcUXtBOtFFpIN+EB04Bd3kaQOrof/JBVC6?= =?us-ascii?Q?1Egq4RDLbpddBLCcW+T6wzLHx8x0BKJxyklQJvNK4IrrXlddv6FzagWU5ugf?= =?us-ascii?Q?PpcnDeT9POi9rGkgT5e6jhVB2YMtu01uLoIJvYwJPkTFF+7j0UYTyOtekDf/?= =?us-ascii?Q?YDSb5WuKF9Uwjx4zQ855POl68b//9kGGC3DWCSJ/FzcbXp0Ec8LGdRUX5mWd?= =?us-ascii?Q?FgrI8H1IC2oTKDCtzxB0U2USqmKN/IVbAAequkcQqk+bml1cZ5mfymfWli2r?= =?us-ascii?Q?Wsei3hrtadCqv712GIMnsD3gRNunh5PPKbXGVC5WzksibVL67/BBgzataJaP?= =?us-ascii?Q?KiI8kdjl1jJkCAlEPE+Hl55mUInd0F5gDBrcuxjVsU9Bm+QfR37DkJEfI8Zm?= =?us-ascii?Q?I9UTI0JZZpjTQAWQYtmc/kJN1qZSRTm1hy0bYc72X1y+oW8yHMM+tBSFDS4O?= =?us-ascii?Q?9G3r9MgK2VkUc1jNSZuXFVvtkB9bLO9r2pwf3GqUgVPSZ92fcCQcLXcWkSkc?= =?us-ascii?Q?+5ZL1caLPJJdNpT6lgrbs4LkXq3Y6L7WLGBC9DEP3bLaQ7vYalwsxFBmwbyB?= =?us-ascii?Q?Cmr70lf3jPKg3nLCwC/TApZ/iJAX6s4CFkfU7kgGEcB3ee7XZLZ4Urj+QXFm?= =?us-ascii?Q?IRl5XXcu5gEuVN+14pzLeSiMsQqLvfOYcC9eZ5//7JFr9UBXWdo/bVFrV3VD?= =?us-ascii?Q?17iVQp/M8WIaX481qJ2zurS+BFhnQVMusUXUujj8GQeONvq9fiZUBqh1bChI?= =?us-ascii?Q?uVmyckrF1+Ng6BJ7Qke2WfqdVEd3TqtcIOMlNkEE/xfTQaiRuhNzXlL4ZBW0?= =?us-ascii?Q?zCLoeZ+LBjQ7rgOk7OA=3D?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: ad9a7708-9cda-414d-25ee-08d9cf9ca8ee X-MS-Exchange-CrossTenant-AuthSource: DM6PR12MB5520.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 04 Jan 2022 16:10:00.8162 (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: bcfRN5MeWjlTeMGrEq5QDNHo3xfNOgUw2RQHnFoR931XjKQ4YqU1SH5RULBpTPIN X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM4PR12MB5389 Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org On Tue, Jan 04, 2022 at 03:49:07AM +0000, Tian, Kevin wrote: > btw can you elaborate the DOS concern? The device is assigned > to an user application, which has one thread (migration thread) > blocked on another thread (vcpu thread) when transiting the > device to NDMA state. What service outside of this application > is denied here? The problem is the VM controls when the vPRI is responded and migration cannot proceed until this is done. So the basic DOS is for a hostile VM to trigger a vPRI and then never answer it. Even trivially done from userspace with a vSVA and userfaultfd, for instance. This will block the hypervisor from ever migrating the VM in a very poor way - it will just hang in the middle of a migration request. Regardless of the complaints of the IP designers, this is a very poor direction. Progress in the hypervisor should never be contingent on a guest VM. Jason