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X-MS-Exchange-AntiSpam-MessageData: =?us-ascii?Q?UrcD6UI6FOO8XIlpo4+4HzHSkllZ59ZrQQ9SuAdopCf8q2QNe12odO0/b8rc?= =?us-ascii?Q?/tyzgd6uYM3Irq2U0/jxSUxRP1m0IpDPLLMJBTtMPSJpchMPu6jCtoMX/1nY?= =?us-ascii?Q?52+UjBaAVOPyRoOLDKzCH3J+C1AGVlbVAfOSFTaDr7ZQsMlRMsoAMqC4nGd7?= =?us-ascii?Q?7R+4T+1PP4rD2vUEaudI6arDVa2DuuB2dC4iRwvZEQkV+n9zgrmkLRHIH8gw?= =?us-ascii?Q?//VI8HjKAerYB6blGKDWvOG+v7p5Py1m4UrafiawOm48TPE42J4wV6ZFKcak?= =?us-ascii?Q?yID8BcB5DeSTaWStchMk7ZAqfZ/EdUpxJ16BEbP30kqY4jWa2kiqTvk7tgnm?= =?us-ascii?Q?pZaOzDceCEq9tSMRHphUIctYozGhmVw9hFEAv5BS6r9uztx3MRlGZxEOeg2Y?= =?us-ascii?Q?WvcWfTiHfeOW4qqiAv1D6nY3ALiKvhjbbuY5cpXT8CxnW57tFnWY9NLLOT+b?= =?us-ascii?Q?KjhM3Q3Ph+ZOmeal3ooQcuqsWe4wCD94gL8fA5JgT+6MHa1j2ZY4kF0FpKqj?= =?us-ascii?Q?WpaqaPStZaJBKPXV6sxHMXVdwrhntckN2O3nST2Z0xkt/QM0Wsvps/wFDajh?= =?us-ascii?Q?eczWsUBUTjLC+nsXgctqgRJD+eYjL942RyWCPp1er9u1+az9Xusho/nFbNpc?= =?us-ascii?Q?sOGgS+z3m4xNFMckEHD1yvpRvQ0UMXjgcjKIJDrLI0rvKFqSR6AyJOOwdXjt?= =?us-ascii?Q?aqaQ5f38fx2fMzMnq8l9Jap5AVmMXEjYjCiJF1O4Q4Cfynxl8KnGrreBGV9i?= =?us-ascii?Q?5mADjmxl3oB2/JXgwBwyEuQsST8olvu7UgFG/MQITvJamW+8kmbKt8/J6xpR?= =?us-ascii?Q?P6TE55X7iDpfWAzzQVcdKJQlSzQArd1jLAm1DJbgF/7m5WltafwSu188tJsR?= =?us-ascii?Q?zVK5jpvSaiW6nhujgQVBSnjDRKtmaBBzD6oaEai1ipl+Naume2FJRcuMPpBq?= =?us-ascii?Q?dRXc2Memfb0krsyy0D9+y8Sd7t/YyDsBKq5nfWNr8mRiXZupnsNVd299pAD9?= =?us-ascii?Q?7IqZNMRrbj2RTgI02ooU2cN5TcIhNmwaXhQYi8s6CXU8Am4u0HBzKeQ2bvxl?= =?us-ascii?Q?4gjzwUr0nTnDsCrWNTdVOszF4KvU5pcPnzLeIWEtMySaUhZDVK+kBaIgDcP5?= =?us-ascii?Q?j5EwiRDuShs/3AF4G22+MCrhmenWo6V922oGXSZva0vi6HAtypBiUHepiBiI?= =?us-ascii?Q?jSRnLNeE+UL3dbPJcuJSyNxnMxzZo2S0QYug7I2XGsXJVBLYE5l8I1VN1MY8?= =?us-ascii?Q?Hh3cVSBaowJSiFY3jpF4KueyrklrJfSb9m3rc6AJGSGCRixkaVX/frnmQKw7?= =?us-ascii?Q?f7DnSj113eH4cEvSOEEcfaPy?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: d5889c89-320a-47c5-4d97-08d929dd5c6f X-MS-Exchange-CrossTenant-AuthSource: BL0PR12MB5506.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 07 Jun 2021 17:54:56.6488 (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: efxXMXQU82aMItR2QmmD9W1NMbZ/MNTefs4tWVRo7JjAme+QuaUM9fkayGoPNI/K X-MS-Exchange-Transport-CrossTenantHeadersStamped: BL1PR12MB5255 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jun 04, 2021 at 11:10:53PM +0000, Tian, Kevin wrote: > > From: Jason Gunthorpe > > Sent: Friday, June 4, 2021 8:09 PM > > > > On Fri, Jun 04, 2021 at 06:37:26AM +0000, Tian, Kevin wrote: > > > > From: Jason Gunthorpe > > > > Sent: Thursday, June 3, 2021 9:05 PM > > > > > > > > > > > > > > > > 3) Device accepts any PASIDs from the guest. No > > > > > > vPASID/pPASID translation is possible. (classic vfio_pci) > > > > > > 4) Device accepts any PASID from the guest and has an > > > > > > internal vPASID/pPASID translation (enhanced vfio_pci) > > > > > > > > > > what is enhanced vfio_pci? In my writing this is for mdev > > > > > which doesn't support ENQCMD > > > > > > > > This is a vfio_pci that mediates some element of the device interface > > > > to communicate the vPASID/pPASID table to the device, using Max's > > > > series for vfio_pci drivers to inject itself into VFIO. > > > > > > > > For instance a device might send a message through the PF that the VF > > > > has a certain vPASID/pPASID translation table. This would be useful > > > > for devices that cannot use ENQCMD but still want to support migration > > > > and thus need vPASID. > > > > > > I still don't quite get. If it's a PCI device why is PASID translation required? > > > Just delegate the per-RID PASID space to user as type-3 then migrating the > > > vPASID space is just straightforward. > > > > This is only possible if we get rid of the global pPASID allocation > > (honestly is my preference as it makes the HW a lot simpler) > > > > In this proposal global vs. per-RID allocation is a per-device policy. > for vfio-pci it can always use per-RID (regardless of whether the > device is partially mediated or not) and no vPASID/pPASID conversion. > Even for mdev if no ENQCMD we can still do per-RID conversion. > only for mdev which has ENQCMD we need global pPASID allocation. > > I think this is the motivation you explained earlier that it's not good > to have one global PASID allocator in the kernel. per-RID vs. global > should be selected per device. I thought we concluded this wasn't possible because the guest could choose to bind the same vPASID to a RID and to a ENQCMD device and then we run into trouble? Are are you saying that a RID device gets a complete dedicated table and can always have a vPASID == pPASID? In any event it needs clear explanation in the next RFC Jason