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Mon, 14 Feb 2022 12:38:44 +0000 Date: Mon, 14 Feb 2022 08:38:42 -0400 To: Greg Kroah-Hartman Subject: Re: [PATCH v5 07/14] PCI: Add driver dma ownership management Message-ID: <20220214123842.GT4160@nvidia.com> References: <20220104015644.2294354-1-baolu.lu@linux.intel.com> <20220104015644.2294354-8-baolu.lu@linux.intel.com> Content-Disposition: inline In-Reply-To: X-ClientProxiedBy: BL1PR13CA0157.namprd13.prod.outlook.com (2603:10b6:208:2bd::12) To MN2PR12MB4192.namprd12.prod.outlook.com (2603:10b6:208:1d5::15) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 56129559-4e88-49a7-4b32-08d9efb6efce X-MS-TrafficTypeDiagnostic: BN8PR12MB3281:EE_ X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:8273; 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:255.255.255.255; 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charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" On Mon, Feb 14, 2022 at 11:03:42AM +0100, Greg Kroah-Hartman wrote: > On Tue, Jan 04, 2022 at 09:56:37AM +0800, Lu Baolu wrote: > > Multiple PCI devices may be placed in the same IOMMU group because > > they cannot be isolated from each other. These devices must either be > > entirely under kernel control or userspace control, never a mixture. This > > checks and sets DMA ownership during driver binding, and release the > > ownership during driver unbinding. > > > > The device driver may set a new flag (no_kernel_api_dma) to skip calling > > iommu_device_use_dma_api() during the binding process. For instance, the > > userspace framework drivers (vfio etc.) which need to manually claim > > their own dma ownership when assigning the device to userspace. > > > > Signed-off-by: Lu Baolu > > include/linux/pci.h | 5 +++++ > > drivers/pci/pci-driver.c | 21 +++++++++++++++++++++ > > 2 files changed, 26 insertions(+) > > > > diff --git a/include/linux/pci.h b/include/linux/pci.h > > index 18a75c8e615c..d29a990e3f02 100644 > > +++ b/include/linux/pci.h > > @@ -882,6 +882,10 @@ struct module; > > * created once it is bound to the driver. > > * @driver: Driver model structure. > > * @dynids: List of dynamically added device IDs. > > + * @no_kernel_api_dma: Device driver doesn't use kernel DMA API for DMA. > > + * Drivers which don't require DMA or want to manually claim the > > + * owner type (e.g. userspace driver frameworks) could set this > > + * flag. > > Again with the bikeshedding, but this name is a bit odd. Of course it's > in the kernel, this is all kernel code, so you can drop that. And > again, "negative" flags are rough. So maybe just "prevent_dma"? That is misleading too, it is not that DMA is prevented, but that the kernel's dma_api has not been setup. Though I agree the name as-is isn't great, I think the comment is good. Jason _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu