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Wed, 12 Apr 2023 17:44:05 -0700 Date: Wed, 12 Apr 2023 17:44:04 -0700 From: Nicolin Chen To: Jason Gunthorpe CC: Yi Liu , , , , , , , , , , , , , , , , , , , Subject: Re: [PATCH 01/12] iommu: Add new iommu op to create domains owned by userspace Message-ID: References: <20230309080910.607396-1-yi.l.liu@intel.com> <20230309080910.607396-2-yi.l.liu@intel.com> 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: DM6NAM11FT042:EE_|MW6PR12MB8949:EE_ X-MS-Office365-Filtering-Correlation-Id: 64ba65ba-8f36-4a8d-0ac6-08db3bb83776 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: +h//9CmEUZ+hlGs+SqnjWzSY6PMvgK7mPX/0qmbkbIPp+DWnsP08xKWVqdBZ3q7nQw4+wNYLvKTMmw18+KorkkyHLLqHLKYYasFrFUUc82bd2V/zaW8V4n7YmRuXz5kJsVQzntCSn5O8p/yMXtfwqo/kAYPaYXuApcSBqlsqCdhhZ0swJDRQpCSjjkfaGzOI3NrLZLCLNbdKbvLp891iDnTOzRw2JTXQDWIJZDF4ByjfdzsN0o74InflSJlrKOv92i4j07BvdydPyddjr74MOr/KjTwPEW7VGBSR00JN/bNH+/8iCqER/IvjgkSJW7IH4YZ/3GrOChxXHhtkDxfnsJs8KFvc/HpCwzz+z9aXhE0AwhMDGjCl72V6dP9IqHUiF38fk+UOgJ7kdLP9Et7l18MBLmIbvZ0K0uqAMMiN+go32MGQqDYrz62NsclhKiQnx/thmIMgkYnRr2lKgAAbzTDgEs+yQ8XeQ4ILeOE4iCXPkf2xeEoJerjQdcSPUVFq6OKVGVhbdUCL06D/NyUQGSAkUNB2R8W87OAxYcXiiX3eGmMVlYv/lCFLviZaGOKQtJTd/+neCBowCKsyEdb009JX1r1gcAN7cd424B8w6Ehf4ZoDdSqYxfOq75c1PgpHl8v8dxH3GDlB1a6troGlmfiGeG6MuZ9BK+ZgXx8tLtXJY1yx9a1czpjIosAMOJVlDG7mYiiziKBsrWRVr84Z1ZrQb94lKfvzAyuomJCxxKDn9vLS2KzeBZmPtSZ2kUnEALKcDL27AMzipkWZAmHCbHkU6xlK7hjxHwuHaXD5x3c= X-Forefront-Antispam-Report: CIP:216.228.117.160;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:mail.nvidia.com;PTR:dc6edge1.nvidia.com;CAT:NONE;SFS:(13230028)(4636009)(346002)(136003)(396003)(39860400002)(376002)(451199021)(46966006)(40470700004)(36840700001)(86362001)(316002)(41300700001)(6636002)(54906003)(70206006)(4326008)(70586007)(478600001)(8676002)(5660300002)(40480700001)(8936002)(6862004)(82310400005)(36860700001)(33716001)(55016003)(2906002)(7636003)(7416002)(34020700004)(82740400003)(356005)(186003)(83380400001)(9686003)(26005)(336012)(426003)(47076005)(40460700003);DIR:OUT;SFP:1101; X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 13 Apr 2023 00:44:19.2311 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 64ba65ba-8f36-4a8d-0ac6-08db3bb83776 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: DM6NAM11FT042.eop-nam11.prod.protection.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: MW6PR12MB8949 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Hi Jason, On Thu, Mar 09, 2023 at 08:56:06PM -0400, Jason Gunthorpe wrote: > On Thu, Mar 09, 2023 at 12:08:59AM -0800, Yi Liu wrote: > > diff --git a/include/linux/iommu.h b/include/linux/iommu.h > > index 3ef84ee359d2..a269bc62a31c 100644 > > --- a/include/linux/iommu.h > > +++ b/include/linux/iommu.h > > @@ -229,6 +229,7 @@ struct iommu_iotlb_gather { > > * after use. Return the data buffer if success, or ERR_PTR on > > * failure. > > * @domain_alloc: allocate iommu domain > > + * @domain_alloc_user: allocate user iommu domain > > * @probe_device: Add device to iommu driver handling > > * @release_device: Remove device from iommu driver handling > > * @probe_finalize: Do final setup work after the device is added to an IOMMU > > @@ -266,6 +267,9 @@ struct iommu_ops { > > > > /* Domain allocation and freeing by the iommu driver */ > > struct iommu_domain *(*domain_alloc)(unsigned iommu_domain_type); > > + struct iommu_domain *(*domain_alloc_user)(struct device *dev, > > + struct iommu_domain *parent, > > + const void *user_data); > > Since the kernel does the copy from user and manages the zero fill > compat maybe this user_data have a union like Robin suggested. > > But yes, this is the idea. > > Reviewed-by: Jason Gunthorpe We pass in a read-only data to this ->domain_alloc_user() while it also returns NULL on failure, matching ->domain_alloc(). So, there seems to be no error feedback pathway from the driver to user space. Robin remarked in the SMMU series that an STE configuration can fail. So, a proper error feedback is required for this callback too. To return a driver/HW specific error, I think we could define a "u8 out_error" in the user_data structure. So, we probably need a non-const pass-in here. What do you think? Thanks Nic