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Fri, 15 Aug 2025 04:06:44 -0700 From: Dragos Tatulea To: , , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman CC: Dragos Tatulea , , , , Christoph Hellwig , , Subject: [RFC net-next v3 1/7] queue_api: add support for fetching per queue DMA dev Date: Fri, 15 Aug 2025 14:03:42 +0300 Message-ID: <20250815110401.2254214-3-dtatulea@nvidia.com> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20250815110401.2254214-2-dtatulea@nvidia.com> References: <20250815110401.2254214-2-dtatulea@nvidia.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-NV-OnPremToCloud: ExternallySecured X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BN3PEPF0000B06F:EE_|DM6PR12MB4283:EE_ X-MS-Office365-Filtering-Correlation-Id: 526f68f2-114c-4a1f-d41c-08dddbebdc04 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|82310400026|36860700013|7416014|376014; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?iC1fuNCAaAXrwOAP/jm3MTaD58MgL+sNZsrjV1fC8zZXqMMCCopSKm9YLheu?= =?us-ascii?Q?7y9q1lEY4kkftsixAsbWTMvepZ/WIWm7WF0oIt2IHc3NLJZPvdpGd7rovyjo?= =?us-ascii?Q?JTKeofUvIJvGRw8+4YdYzAsW7CMw4I4dTw/B5V0ILLgzyvYtI91q+vU91p2X?= =?us-ascii?Q?Ll+Y7k6/wHihitH2dq6tmf/ppFol3h/f7zBTTKbml+baGfoCDyYZ1oTkoz3O?= =?us-ascii?Q?aOlo+D9NhzrrSvM5e38+GyOB8llbmGERp2iUVwFSMLdi9VNlBJqxtYu12SYG?= =?us-ascii?Q?kUCfmZ7Sn7OTtUMyGnwICrynOLGfmqXvvxgry12CuEBUIlqH15+OeSNK4Gte?= =?us-ascii?Q?0GgiHMtxUgaGRmZNMDBiVq9Uwgy3mZOrisgOua4mc9zcK8vTyTYKgmrg87LY?= =?us-ascii?Q?vlraeXZwEMqsUmI9mUnQ4HbqkhlOOcyD7scHMT/Y3GHx7yDYoEPiY/47NDJV?= =?us-ascii?Q?66I+jNp1rtmnuRNR9lfze84h2Zt4pulRcqWwC6bR2RvH79z5TcYPqtWlwO8c?= =?us-ascii?Q?meYLeG0OrEB4yT/k+uAFv+c8/cTs1ptpPghfDzAFz6KdqvDAoda7LoSFMVwG?= =?us-ascii?Q?SrWgCXxoMJtsBGDWFvMjScl8gOzpRFyZFRqlsSIshshphBrENnRkuPBn6gKD?= =?us-ascii?Q?gDwj1ykZFGGMAeU/Ct/PLMspb8D5Du/RQWzE3qsqLhaFMtFZ0wqunn/aWFOC?= =?us-ascii?Q?FkaCMXOeXiL5pHHNOJViSrVavf0ScYmYY3LS5eXFSKSiPdQ05wKj/bR2tamn?= =?us-ascii?Q?pRpBpFoCfc/EcOTro6x1M+iYG5cyDWSGVZqeCgeiXoEfjW/rMiTAb0Eo2c8W?= =?us-ascii?Q?0Fel4oiIwrZ8+B/CiDQNpRVYpvQ6lX0yNzsCxZeRZANZZ2N8ZgCumYhcj/4M?= =?us-ascii?Q?EUjxdEyTHlDaCGb9tCRgFHJ4HjE/2KpnFPsa61TgmhSWsQ+BvIiuijfCaI2L?= =?us-ascii?Q?e4jn6CvhV9DK6CASyDgPixCsHfNQQeopeO/px5sq/5rWsah2feYtfR7Q7VNT?= =?us-ascii?Q?J0QDqX/L2PmR2LyogCslMI3nMULYSavEdvYpDjEAVi+r9dILOZpOAcz1PG/F?= =?us-ascii?Q?iqM1G/lFVjCCXxSlKE+2Brbff7GrWJwA1UpTBHKN/qikVBlX5BMw0+LLKUvh?= =?us-ascii?Q?UeQ+eakP62h3pOrl6xxq0dVk7ldgAodHGkqrRE+1WbCC57AaMHJukrnTPBuv?= =?us-ascii?Q?x8JOMeEmmzjoMSR1O2PgirALj1pDW9Xe3qD7uDrouxv6ubVJzENMh5u5XbU5?= =?us-ascii?Q?SpKM7QV9sEQAv2nXpR7O8og8FRM1wZxOpp73nRkjV9jDWgxG3X/tdNxt+Tqb?= =?us-ascii?Q?whLdixiNV8AvKmbKXqOikMjuUNG2EQxYKqbgMYnNZIfllAVlMjj4MJfm+qB2?= =?us-ascii?Q?Zc4/TKXxG7SpCPac81YCMFe14qxsebu+Q8nWGyZe+UBwy4uRgXaOURQwWZ/p?= =?us-ascii?Q?xh+kSE/ZfBoyZW2bLIdz0HFvuEO1PTGR5edjXvzFpP13oz8L3sED++Vk6THa?= =?us-ascii?Q?EDstYFOSXH+3cKml3QT20HcLxop40eQrlmtJ?= X-Forefront-Antispam-Report: CIP:216.228.117.161;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:mail.nvidia.com;PTR:dc6edge2.nvidia.com;CAT:NONE;SFS:(13230040)(1800799024)(82310400026)(36860700013)(7416014)(376014);DIR:OUT;SFP:1101; X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 15 Aug 2025 11:07:00.9806 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 526f68f2-114c-4a1f-d41c-08dddbebdc04 X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.117.161];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: BN3PEPF0000B06F.namprd21.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM6PR12MB4283 Content-Type: text/plain; charset="utf-8" For zerocopy (io_uring, devmem), there is an assumption that the parent device can do DMA. However that is not always the case: - Scalable Function netdevs [1] have the DMA device in the grandparent. - For Multi-PF netdevs [2] queues can be associated to different DMA devices. This patch introduces the a queue based interface for allowing drivers to expose a different DMA device for zerocopy. [1] Documentation/networking/device_drivers/ethernet/mellanox/mlx5/switchde= v.rst [2] Documentation/networking/multi-pf-netdev.rst Signed-off-by: Dragos Tatulea Reviewed-by: Pavel Begunkov --- include/net/netdev_queues.h | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/include/net/netdev_queues.h b/include/net/netdev_queues.h index 6e835972abd1..d4d8c42b809f 100644 --- a/include/net/netdev_queues.h +++ b/include/net/netdev_queues.h @@ -127,6 +127,10 @@ void netdev_stat_queue_sum(struct net_device *netdev, * @ndo_queue_stop: Stop the RX queue at the specified index. The stopped * queue's memory is written at the specified address. * + * @ndo_queue_get_dma_dev: Get dma device for zero-copy operations to be u= sed + * for this queue. When such device is not available, + * the function will return NULL. + * * Note that @ndo_queue_mem_alloc and @ndo_queue_mem_free may be called wh= ile * the interface is closed. @ndo_queue_start and @ndo_queue_stop will only * be called for an interface which is open. @@ -144,6 +148,8 @@ struct netdev_queue_mgmt_ops { int (*ndo_queue_stop)(struct net_device *dev, void *per_queue_mem, int idx); + struct device * (*ndo_queue_get_dma_dev)(struct net_device *dev, + int idx); }; =20 /** @@ -321,4 +327,18 @@ static inline void netif_subqueue_sent(const struct ne= t_device *dev, get_desc, start_thrs); \ }) =20 +static inline struct device * +netdev_queue_get_dma_dev(struct net_device *dev, int idx) +{ + const struct netdev_queue_mgmt_ops *queue_ops =3D dev->queue_mgmt_ops; + struct device *dma_dev; + + if (queue_ops && queue_ops->ndo_queue_get_dma_dev) + dma_dev =3D queue_ops->ndo_queue_get_dma_dev(dev, idx); + else + dma_dev =3D dev->dev.parent; + + return dma_dev && dma_dev->dma_mask ? dma_dev : NULL; +} + #endif --=20 2.50.1