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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?wy3ksSLkCkWu3/5mpmpmCl/udjx99oWtFYyMCkD47SeisaeDfnw5ZAujnDxu?= =?us-ascii?Q?U6DW3i6hI7yohhPsnEZehI9U29J89aTr7OvBSjOat/UGCCWupvSXtBo2Sj0n?= =?us-ascii?Q?+vBqnQPvJpyafaDVzt208QI/kSrrvRwImDx/3O9LWQZw2yrgyNerDa07sAD0?= =?us-ascii?Q?bkcbkIcdzxnN7TZkmKM+vGkZBk4RWQXoRJ2YcieC9zMVijn3fQONkr1LmfJc?= =?us-ascii?Q?8QNj22L5OmwJlPPE9Kk4bZHkDBWM+IEyHXu+BBRYRPJboG4p0+DkVKnIQnEv?= =?us-ascii?Q?UwdGXx5GLzBkjR+Wndp0dMauWjUWwaEAjCYHkSfBHobk5+Au0RvjMPzKfb31?= =?us-ascii?Q?31lZEPosbXk1YEci4eYCmjQWYdXWLaiNM2ACD5EcC/UEbAKMyTNBiBsNaRMD?= =?us-ascii?Q?wbJzFa7zgtQx3BYL2K3BFDyuLclDqci3ecj3F0QT2RlWoUU4S8vHSQxUI6DW?= =?us-ascii?Q?LoXs81OU3th+RQR67HwDeY2Tc+AF8DaO1lzE2Lvmtcisoq/vSJwstU2f/mbm?= =?us-ascii?Q?xzC6UWm4ddpNt+mFF6JkIYkXJn9mqII1PlRlj7y4r1bUta9kQuQLk7pPgz+M?= =?us-ascii?Q?8FEr3hKMGurldJpQLOwsk1+JyU9LNepsiZY7GRZi++VRyk4hb5hOktEsF6qW?= =?us-ascii?Q?YGpGoDEPSDtj3zhr72vlrO01O51MWOPdXLTXx1J2gAr5E0nEmA1VG0f2aK9S?= =?us-ascii?Q?uQIo71+RBFmAk4/95UQtJHw+ITmgS3o8XWVPxO3ZbcKZ4+L9sV2y6St4Et42?= =?us-ascii?Q?y6uGiJXyChlNcXOGZBUg9Hbnx02MwkLo0T/JusY3vLueHGDE8grZOKaniZ3X?= =?us-ascii?Q?DkQWuuZDdNwlrIA9BHAQ1uPIMY21CN383VkKBh0eVP7tfcb3gzLhfUb/zvK9?= =?us-ascii?Q?z7SQJVFrzep5gGs4rzOck8PG3vy9EMhKGhfD5hzkPK1Gk5x5hUDboObzXEjJ?= =?us-ascii?Q?hSWtUuV/E+6EL1UJuwI6M3rxyZvDswphVtdTLmfa9kkBwicPrK3/K4Sqb2X0?= =?us-ascii?Q?JkFHmt+ZdwhPs0XVaASh1qGfeOHSj4jfcMjM0ugI5p5ypF64FYACIJdXD1Vi?= =?us-ascii?Q?pkUJUlWRNqcApThyqNnji9FRxFFESVIzp3IfYz6GZ66S8KNMZctCHc63V7Y+?= =?us-ascii?Q?B9wNjZf4PWepYd9Byxx54IB93Ml6CfYLoHIzeB/NDxU418kJUWHJJTWdp5A8?= =?us-ascii?Q?e64L8ql0pMw728JRS5AvKpxpmns+0yJeJe6vsi73H6iFtI5xmvjUIZFFpHpY?= =?us-ascii?Q?eFbhaP9U7vQ5w7IQoBxvckU+tWNGBteUyBKOzf8Ovr+Pfn8g4R6HDxgaavHQ?= =?us-ascii?Q?LFgJSlOXT44utWA0cUT6zMQluhUw9HBEc97JPoB7xJ7SceH6q4OmmiTexUGG?= =?us-ascii?Q?suHTjrO4e4yHJRyALYtYAylf9Go3rh9aUi7I6TRSWCWA0pcp5k8//e9YIZoI?= =?us-ascii?Q?BThs1ckwEGbE3iQRtW3vKMm3pKgdPvrAFd5KOrcNVMPcXxIKY+BXmp+YBYsB?= =?us-ascii?Q?5OPKWqe45Hxts9AQfJfxaaI5knZ92fk9u54PMItC96d4VN2J6z6dNjboBpoD?= =?us-ascii?Q?r/sC9uoTeT3VSwaggaGkrmloBH76jm0yLFQxmbKU?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 61d97193-d9fb-4a46-a81b-08db8f65f37e X-MS-Exchange-CrossTenant-AuthSource: LV2PR12MB5869.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 28 Jul 2023 12:27:04.4425 (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: pF05ka04lTE/4j4JOwYZNTcBNYtj066PalT2zVZ5G444zjH2CGCQ7+0MOMQjOwkd X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH0PR12MB7813 Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org On Thu, Jul 27, 2023 at 12:04:00PM -0700, Nicolin Chen wrote: > On Thu, Jul 27, 2023 at 09:03:01AM -0300, Jason Gunthorpe wrote: > > On Wed, Jul 26, 2023 at 07:59:11PM -0700, Nicolin Chen wrote: > > > > > I just realized that either my v8 or your version calls unmap() > > > first at the entire cur_ioas. So, there seems to be no point in > > > doing that fallback re-add routine since the cur_ioas isn't the > > > same, which I don't feel quite right... > > > > The point is to restore the access back to how it should be on failure > > so future use of the accesss still does the right thing. > > > > We already have built into this a certain non-atomicity for mdevs, > > they can see a pin failure during replace if they race an access > > during this unmap window. This is similar to the real HW iommu's > > without atomic replace. > > I was concerned about, after the replace, mdev losing all the > mappings due to the unmap() call, which means the fallback is > not really a status quo. Do you mean that they could pin those > lost mappings back? At this point their shouldn't be mappings in any path with a chance of success, as I said it is racy already. Not sure we need to fuss about it futher. Jason