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Fri, 3 Feb 2023 14:25:15 -0800 Date: Fri, 3 Feb 2023 14:25:14 -0800 From: Nicolin Chen To: "Tian, Kevin" , Jason Gunthorpe CC: "joro@8bytes.org" , "will@kernel.org" , "robin.murphy@arm.com" , "alex.williamson@redhat.com" , "shuah@kernel.org" , "Liu, Yi L" , "linux-kernel@vger.kernel.org" , "iommu@lists.linux.dev" , "kvm@vger.kernel.org" , "linux-kselftest@vger.kernel.org" , "baolu.lu@linux.intel.com" Subject: Re: [PATCH v1 5/8] iommufd: Add replace support in iommufd_access_set_ioas() Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DS1PEPF0000E63A:EE_|IA1PR12MB8310:EE_ X-MS-Office365-Filtering-Correlation-Id: b9e168c0-39d2-44a5-ca3f-08db06358d33 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:216.228.118.233;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:mail.nvidia.com;PTR:dc7edge2.nvidia.com;CAT:NONE;SFS:(13230025)(4636009)(136003)(39860400002)(376002)(396003)(346002)(451199018)(46966006)(36840700001)(40470700004)(70206006)(70586007)(83380400001)(41300700001)(36860700001)(47076005)(82740400003)(33716001)(426003)(7636003)(336012)(82310400005)(8676002)(4326008)(55016003)(356005)(316002)(186003)(40480700001)(9686003)(40460700003)(8936002)(2906002)(26005)(6636002)(110136005)(7416002)(54906003)(478600001)(5660300002)(86362001);DIR:OUT;SFP:1101; X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 03 Feb 2023 22:25:27.3822 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: b9e168c0-39d2-44a5-ca3f-08db06358d33 X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.118.233];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: DS1PEPF0000E63A.namprd02.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: IA1PR12MB8310 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Fri, Feb 03, 2023 at 08:31:52AM -0400, Jason Gunthorpe wrote: > On Fri, Feb 03, 2023 at 10:10:45AM +0000, Tian, Kevin wrote: > > > From: Nicolin Chen > > > Sent: Thursday, February 2, 2023 3:05 PM > > > > > > Support an access->ioas replacement in iommufd_access_set_ioas(), which > > > sets the access->ioas to NULL provisionally so that any further incoming > > > iommufd_access_pin_pages() callback can be blocked. > > > > > > Then, call access->ops->unmap() to clean up the entire iopt. To allow an > > > iommufd_access_unpin_pages() callback to happen via this unmap() call, > > > add an ioas_unpin pointer so the unpin routine won't be affected by the > > > "access->ioas = NULL" trick above. > > > > > > Also, a vdev without an ops->dma_unmap implementation cannot replace its > > > access->ioas pointer. So add an iommufd_access_ioas_is_attached() helper > > > to sanity that. > > > > > > > Presumably a driver which doesn't implement ops->dma_unmap shouldn't > > be allowed to do pin/unpin. But it could use vfio_dma_rw() to access an > > iova range. In the latter case I don't see why replace cannot work. > > > > Probably what's required here is to deny !ops->dma_unmap in > > vfio_pin/unpin_pages then making here replace always allowed? > > That makes sense Will change that in v2. Thanks Nic