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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?ZccDh1b34sglTVmRRR1W28dSDPc6RHh9qFvuypGzx9uvdK1ycSgEoH4vZp9K?= =?us-ascii?Q?Yhl+/TYMS+9pfrYgO45+0n60L5caRWIlkAaTtsWTAFegmbOA21U14rwBa0BZ?= =?us-ascii?Q?Uv2QpnTIU09YcjcxBrT04a1hif/0lAVCZwJoqVDPLqkB7F5DVAkBTVuopWI5?= =?us-ascii?Q?/9ITDdMQcdkDJ7HRdl6EhyApOQgoxQP8thPIEQtyP7CSO//QVky8+1DC8ICc?= =?us-ascii?Q?NtkRTxFqn/Ght8UWV/Xf0TsqdNFybX9IsjruC7DOGzpMbecXrGupy98J8+g6?= =?us-ascii?Q?VUFO+WNIRM8Cvx+dp3U3QGf9ukJHkAKpH1QJKZKF2RQdZ8FEbcBOUI0gQjVJ?= =?us-ascii?Q?bFNYy81Wlx7gaJchItQzm6ygnQrErYidNWtbVWDCdIGrdG4zw+EmxAwNvORD?= =?us-ascii?Q?Vz71MQ1oBYoGBZGNJePLWKiaArJNxF4wX5i7HXzf3SH2inZk5TGnmZi5AIJM?= =?us-ascii?Q?Vix2Vkc/vFW+DfCq/bHnkjv3wTzuxOfXIzKuoWxHELwFwZs+SzK3louISIad?= =?us-ascii?Q?PBa2A2cjhAvhZI1Q/9LIUg0zrnZOz6w1Zi3RpNTKsCOh/aebLvRwlXGfIa5W?= =?us-ascii?Q?QeuhZjy+juT1dB55uA3qZw7gwbqolMQAbfZA2Yy/W5T9+Fqrt+W7BYTsx4AA?= =?us-ascii?Q?acfYTPrqYBJSx2Mlj6fTwLFqbpkku7RSb7diY03u7PP+qkoXrxoqi0+J0Px+?= =?us-ascii?Q?pY8QEeS4HskhkMa3Yx10y4AlEYRkVT2CTrdNjPEa21Xz0xU30+lpkrP7wZkE?= =?us-ascii?Q?qztcnyGDecH2DbD9VHrxr7zezPVkDpK6BmGtDID2Oow+BZuEGiV9Rvl7JEz8?= =?us-ascii?Q?kT+jXRRSr0ZdMyHcmAMe0LReOQUrx4TBKTcScvmif1cZRrimoTu5t0RMYLRA?= =?us-ascii?Q?jpGEVdB+PRwAwkiWVsBhzXYX0tFHz9o1nuHTSQ2SllrK7vFE4laFuwc1voZi?= =?us-ascii?Q?YJwPCifYt8lVeonZV38QgM1Dzf/oumjlZzuVQwJqhFc6dVAnROnGeFtgjDYF?= =?us-ascii?Q?r05Xx6a/uoUnMPLqEkmvhZoAUDcSv4aEObk9PyXjDTDlyQ7Z+jff5Ui4ksy0?= =?us-ascii?Q?MezcV+ULTt4vMjMaqX71+QfKDKMA+lucKW6fJl0OXshtsL53ai52eAW0rzbP?= =?us-ascii?Q?eFIni3J7CKxARyxWHd29m+Iq1ymxwUkVMKYhntbap/cMrN4FlWaJRSOX9MRV?= =?us-ascii?Q?4yJd2zfZFHNTmFWhJBCWJql2ep2IFMqHBg9afI9j6JOcgQqXkaJt+Jmt0o07?= =?us-ascii?Q?0jsNIwcYYrt/A9jrzOitcJiefxtlB4viUhigZ2Ds8jrfBF29U9AoMmwDknxL?= =?us-ascii?Q?tgEcxUeWWOZyWXcRmO78psKjJnmi1swXutKFdYWqw2wySL6z2XBRBCXW4IlE?= =?us-ascii?Q?Ldpll6dMt8YqAxKdiqqmLdo+VaTF2xk+o57zxAlPZc4/KxU6BjrZ0GYRXkl6?= =?us-ascii?Q?q6wjzcSDl8YulTiBbewNPdtIlo2Jfb2Wh8uRDfkHRrPdDivksqjkopDttLUF?= =?us-ascii?Q?DDL3OLriU6NuYy695w1+9NV3hSexcjLCReSC+CCX1aDUj4bJq8u6hDIP2xSv?= =?us-ascii?Q?YwQGQHsD4grrHaSTv9AmyDI5ZsTRkRPgEK2NgUbc?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 2a8e41e4-77b7-4360-b17b-08db2c69bf07 X-MS-Exchange-CrossTenant-AuthSource: LV2PR12MB5869.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 24 Mar 2023 13:14:49.3390 (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: 1EZ4RgnJR/c8i944coQ7pe/JEU8rN7M1wpCs5MW59+TOZYaoJy8cTpPPfvq1UWAM X-MS-Exchange-Transport-CrossTenantHeadersStamped: CY8PR12MB7316 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Fri, Mar 24, 2023 at 09:09:59AM +0000, Tian, Kevin wrote: > > From: Alex Williamson > > Sent: Wednesday, March 22, 2023 5:01 AM > > > > On Tue, 21 Mar 2023 17:50:08 -0300 > > Jason Gunthorpe wrote: > > > > > > > > Though it would be nice if qemu didn't need two implementations so Yi > > > I'd rather see a new info in this series as well and qemu can just > > > consistently use dev_id and never bdf in iommufd mode. > > > > We also need to consider how libvirt determines if QEMU has the kernel > > support it needs to pass file descriptors. It'd be a lot cleaner if > > this aligned with the introduction of vfio cdevs. > > > > Libvirt can check whether the kernel creates cdev for a given device > via sysfs. > > but I'm not sure how Libvirt determines whether QEMU supports a > feature that it wants to use. But sounds this is a general handshake > problem as Libvirt needs to support many versions of QEMU then > there must be a way for such negotiation? Ideally libvirt would be able to learn what ioctls are supported on the cdev fd after it opens it, but before binding. I don't think we have something here yet, but I could imagine having something. Clearly it is easier if cdev alone is enough proof to know that it should go ahead in cdev mode. Jason