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Tue, 21 Apr 2026 10:43:46 -0700 Date: Tue, 21 Apr 2026 10:43:44 -0700 From: Nicolin Chen To: "Tian, Kevin" CC: "joro@8bytes.org" , "jgg@nvidia.com" , "will@kernel.org" , "robin.murphy@arm.com" , "baolu.lu@linux.intel.com" , "iommu@lists.linux.dev" , "linux-kernel@vger.kernel.org" , "xueshuai@linux.alibaba.com" Subject: Re: [PATCH rc v6] iommu: Fix nested pci_dev_reset_iommu_prepare/done() Message-ID: References: <20260407194644.171304-1-nicolinc@nvidia.com> Precedence: bulk X-Mailing-List: iommu@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: X-NV-OnPremToCloud: ExternallySecured X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DS2PEPF00003442:EE_|LV3PR12MB9267:EE_ X-MS-Office365-Filtering-Correlation-Id: b0c07350-0616-458b-bcfb-08de9fcd9412 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|36860700016|376014|1800799024|82310400026|56012099003|18002099003|22082099003; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: aFgUJtLgf4pc4i1LHEG+vfDQ+a+BhxcunzmMbm7kQ522je7VRfMSLJBqzt5RllGgIlt53UdcSh2Kuj4Ygn5J5qqhYY2X+V3TMdklOUiEYGDwL0s70l5yvo5IeLTvl53QYAa5SXDTcSHb05cgQRKwDUcCbzL156dMZvuSPt70Bmb6IDSlb2QUV+rdJEQcb2KuX9SFvSCar+Nf6yonjpjGtCUZFp/KvTmK6M9ziOBmwnWifLN4G+t63zzlHT9/kmtp8B/ybMR221SskgGxQ8py3lvWToiNJxiYgh34/MVQTBWP0Pr+WXyGUFMvUFA/a2vYJcKMB2Q1GFGfzLT1/Q8Hwn5bVkhl7/zr0nHzv2EdwXXvt6EcrIhCZlSf8NwMbikk7RCBqnY0hhn+aesN2CBqfeesOnC0V7gKw3jhSelqlg+w+/ugenEcUvUBT5cfv2xP X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 21 Apr 2026 17:44:03.2923 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: b0c07350-0616-458b-bcfb-08de9fcd9412 X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.117.160];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: DS2PEPF00003442.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: LV3PR12MB9267 On Tue, Apr 21, 2026 at 07:01:22AM +0000, Tian, Kevin wrote: > > From: Nicolin Chen > > Sent: Saturday, April 18, 2026 12:57 PM > > > > On Fri, Apr 17, 2026 at 02:44:41PM -0700, Nicolin Chen wrote: > > > @@ -2469,9 +2469,2 @@ static int > > __iommu_group_set_domain_internal(struct iommu_group *group, > > > > > > - /* > > > - * This is a concurrent attach during device recovery. Reject it until > > > - * pci_dev_reset_iommu_done() attaches the device to group->domain. > > > - */ > > > - if (group->recovery_cnt) > > > - return -EBUSY; > > > - > > > > On a second thought, we may not simply drop this -- IIRC, we added > > it particularly to fence a case where gdevs share the same RID or > > some corner case like that? > > > > this is by design according to the original commit: > > " > Note that there are two corner cases: > 1. Devices in the same iommu_group > Since an attachment is always per iommu_group, this means that any > sibling devices in the iommu_group cannot change domain, to prevent > race conditions. > ... > " Well, we changed the implementation a few times, and it isn't in the merged v8 cover-letter.. Nicolin