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Mon, 04 May 2026 06:57:59 -0700 (PDT) Received: from localhost ([85.163.81.98]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-48a8eb69698sm496201345e9.1.2026.05.04.06.57.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 04 May 2026 06:57:59 -0700 (PDT) From: Jiri Pirko To: linux-rdma@vger.kernel.org Cc: jgg@ziepe.ca, leon@kernel.org, mrgolin@amazon.com, gal.pressman@linux.dev, sleybo@amazon.com, parav@nvidia.com, mbloch@nvidia.com, yanjun.zhu@linux.dev, marco.crivellari@suse.com, roman.gushchin@linux.dev, phaddad@nvidia.com, lirongqing@baidu.com, ynachum@amazon.com, huangjunxian6@hisilicon.com, kalesh-anakkur.purayil@broadcom.com, ohartoov@nvidia.com, michaelgur@nvidia.com, shayd@nvidia.com, edwards@nvidia.com, sriharsha.basavapatna@broadcom.com, andrew.gospodarek@broadcom.com, selvin.xavier@broadcom.com Subject: [PATCH rdma-next v3 15/17] RDMA/mlx5: Use UMEM attribute for CQ doorbell record Date: Mon, 4 May 2026 15:57:29 +0200 Message-ID: <20260504135731.2345383-16-jiri@resnulli.us> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260504135731.2345383-1-jiri@resnulli.us> References: <20260504135731.2345383-1-jiri@resnulli.us> Precedence: bulk X-Mailing-List: linux-rdma@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Jiri Pirko Add an optional mlx5 driver-namespace UMEM attribute on CQ create so userspace can supply the doorbell record umem explicitly. Resolve it inside mlx5_ib_db_map_user() and use it as a private DBR page when present; otherwise take the existing UHW share-or-pin path that preserves per-page DBR sharing across CQ/QP/SRQ in the same process. Signed-off-by: Jiri Pirko --- v2->v3: - moved CQ DBR attr to mlx5 driver namespace - changed to use ib_umem_get_attr() to get umem - added page-crossing check --- drivers/infiniband/hw/mlx5/cq.c | 8 +++- drivers/infiniband/hw/mlx5/doorbell.c | 51 ++++++++++++++++++++---- drivers/infiniband/hw/mlx5/mlx5_ib.h | 5 ++- drivers/infiniband/hw/mlx5/qp.c | 4 +- drivers/infiniband/hw/mlx5/srq.c | 2 +- include/uapi/rdma/mlx5_user_ioctl_cmds.h | 1 + 6 files changed, 57 insertions(+), 14 deletions(-) diff --git a/drivers/infiniband/hw/mlx5/cq.c b/drivers/infiniband/hw/mlx5/cq.c index fb6172a9be57..b69ab49b1b3e 100644 --- a/drivers/infiniband/hw/mlx5/cq.c +++ b/drivers/infiniband/hw/mlx5/cq.c @@ -760,7 +760,9 @@ static int create_cq_user(struct mlx5_ib_dev *dev, struct ib_udata *udata, goto err_umem; } - err = mlx5_ib_db_map_user(context, ucmd.db_addr, &cq->db); + err = mlx5_ib_db_map_user(context, udata, + MLX5_IB_ATTR_CREATE_CQ_DBR_BUF_UMEM, + ucmd.db_addr, &cq->db); if (err) goto err_umem; @@ -1519,7 +1521,9 @@ ADD_UVERBS_ATTRIBUTES_SIMPLE( UVERBS_ATTR_PTR_IN( MLX5_IB_ATTR_CREATE_CQ_UAR_INDEX, UVERBS_ATTR_TYPE(u32), - UA_OPTIONAL)); + UA_OPTIONAL), + UVERBS_ATTR_UMEM(MLX5_IB_ATTR_CREATE_CQ_DBR_BUF_UMEM, + UA_OPTIONAL)); const struct uapi_definition mlx5_ib_create_cq_defs[] = { UAPI_DEF_CHAIN_OBJ_TREE(UVERBS_OBJECT_CQ, &mlx5_ib_cq_create), diff --git a/drivers/infiniband/hw/mlx5/doorbell.c b/drivers/infiniband/hw/mlx5/doorbell.c index 020c70328663..c9f9b9179e88 100644 --- a/drivers/infiniband/hw/mlx5/doorbell.c +++ b/drivers/infiniband/hw/mlx5/doorbell.c @@ -45,20 +45,56 @@ struct mlx5_ib_user_db_page { struct mm_struct *mm; }; -int mlx5_ib_db_map_user(struct mlx5_ib_ucontext *context, unsigned long virt, - struct mlx5_db *db) +int mlx5_ib_db_map_user(struct mlx5_ib_ucontext *context, + struct ib_udata *udata, u16 attr_id, + unsigned long virt, struct mlx5_db *db) { - struct mlx5_ib_user_db_page *page; + struct mlx5_ib_user_db_page *page = NULL; + unsigned long dma_offset; int err = 0; + if (udata) { + struct ib_umem *umem; + + umem = ib_umem_get_attr(context->ibucontext.device, udata, + attr_id, sizeof(__be32) * 2, 0); + if (IS_ERR(umem)) + return PTR_ERR(umem); + if (umem) { + /* + * The 8-byte DBR is programmed to the device as one + * DMA address, so it must stay within a single page. + * An 8-byte range that crosses a page boundary may + * be split across two non-contiguous DMA mappings. + */ + if (ib_umem_offset(umem) > + PAGE_SIZE - sizeof(__be32) * 2) { + ib_umem_release(umem); + return -EINVAL; + } + page = kzalloc_obj(*page); + if (!page) { + ib_umem_release(umem); + return -ENOMEM; + } + page->umem = umem; + dma_offset = ib_umem_offset(umem); + } + } + mutex_lock(&context->db_page_mutex); + if (page) + goto add_page; + + dma_offset = virt & ~PAGE_MASK; + list_for_each_entry(page, &context->db_page_list, list) if ((current->mm == page->mm) && (page->user_virt == (virt & PAGE_MASK))) goto found; - page = kmalloc_obj(*page); + page = kzalloc_obj(*page); if (!page) { err = -ENOMEM; goto out; @@ -76,11 +112,11 @@ int mlx5_ib_db_map_user(struct mlx5_ib_ucontext *context, unsigned long virt, mmgrab(current->mm); page->mm = current->mm; +add_page: list_add(&page->list, &context->db_page_list); found: - db->dma = sg_dma_address(page->umem->sgt_append.sgt.sgl) + - (virt & ~PAGE_MASK); + db->dma = sg_dma_address(page->umem->sgt_append.sgt.sgl) + dma_offset; db->u.user_page = page; ++page->refcnt; @@ -96,7 +132,8 @@ void mlx5_ib_db_unmap_user(struct mlx5_ib_ucontext *context, struct mlx5_db *db) if (!--db->u.user_page->refcnt) { list_del(&db->u.user_page->list); - mmdrop(db->u.user_page->mm); + if (db->u.user_page->mm) + mmdrop(db->u.user_page->mm); ib_umem_release(db->u.user_page->umem); kfree(db->u.user_page); } diff --git a/drivers/infiniband/hw/mlx5/mlx5_ib.h b/drivers/infiniband/hw/mlx5/mlx5_ib.h index e156dc4d7529..45bc8928523a 100644 --- a/drivers/infiniband/hw/mlx5/mlx5_ib.h +++ b/drivers/infiniband/hw/mlx5/mlx5_ib.h @@ -1259,8 +1259,9 @@ to_mmmap(struct rdma_user_mmap_entry *rdma_entry) int mlx5_ib_dev_res_cq_init(struct mlx5_ib_dev *dev); int mlx5_ib_dev_res_srq_init(struct mlx5_ib_dev *dev); -int mlx5_ib_db_map_user(struct mlx5_ib_ucontext *context, unsigned long virt, - struct mlx5_db *db); +int mlx5_ib_db_map_user(struct mlx5_ib_ucontext *context, + struct ib_udata *udata, u16 attr_id, + unsigned long virt, struct mlx5_db *db); void mlx5_ib_db_unmap_user(struct mlx5_ib_ucontext *context, struct mlx5_db *db); void __mlx5_ib_cq_clean(struct mlx5_ib_cq *cq, u32 qpn, struct mlx5_ib_srq *srq); void mlx5_ib_cq_clean(struct mlx5_ib_cq *cq, u32 qpn, struct mlx5_ib_srq *srq); diff --git a/drivers/infiniband/hw/mlx5/qp.c b/drivers/infiniband/hw/mlx5/qp.c index 1b764a573dd7..997ea9bcfc55 100644 --- a/drivers/infiniband/hw/mlx5/qp.c +++ b/drivers/infiniband/hw/mlx5/qp.c @@ -918,7 +918,7 @@ static int create_user_rq(struct mlx5_ib_dev *dev, struct ib_pd *pd, ib_umem_num_pages(rwq->umem), page_size, rwq->rq_num_pas, offset); - err = mlx5_ib_db_map_user(ucontext, ucmd->db_addr, &rwq->db); + err = mlx5_ib_db_map_user(ucontext, NULL, 0, ucmd->db_addr, &rwq->db); if (err) { mlx5_ib_dbg(dev, "map failed\n"); goto err_umem; @@ -1056,7 +1056,7 @@ static int _create_user_qp(struct mlx5_ib_dev *dev, struct ib_pd *pd, resp->bfreg_index = MLX5_IB_INVALID_BFREG; qp->bfregn = bfregn; - err = mlx5_ib_db_map_user(context, ucmd->db_addr, &qp->db); + err = mlx5_ib_db_map_user(context, NULL, 0, ucmd->db_addr, &qp->db); if (err) { mlx5_ib_dbg(dev, "map failed\n"); goto err_free; diff --git a/drivers/infiniband/hw/mlx5/srq.c b/drivers/infiniband/hw/mlx5/srq.c index bc22036d7e80..88db0143bc3f 100644 --- a/drivers/infiniband/hw/mlx5/srq.c +++ b/drivers/infiniband/hw/mlx5/srq.c @@ -74,7 +74,7 @@ static int create_srq_user(struct ib_pd *pd, struct mlx5_ib_srq *srq, } in->umem = srq->umem; - err = mlx5_ib_db_map_user(ucontext, ucmd.db_addr, &srq->db); + err = mlx5_ib_db_map_user(ucontext, NULL, 0, ucmd.db_addr, &srq->db); if (err) { mlx5_ib_dbg(dev, "map doorbell failed\n"); goto err_umem; diff --git a/include/uapi/rdma/mlx5_user_ioctl_cmds.h b/include/uapi/rdma/mlx5_user_ioctl_cmds.h index 01a2a050e468..b63e75034cda 100644 --- a/include/uapi/rdma/mlx5_user_ioctl_cmds.h +++ b/include/uapi/rdma/mlx5_user_ioctl_cmds.h @@ -274,6 +274,7 @@ enum mlx5_ib_device_query_context_attrs { enum mlx5_ib_create_cq_attrs { MLX5_IB_ATTR_CREATE_CQ_UAR_INDEX = UVERBS_ID_DRIVER_NS_WITH_UHW, + MLX5_IB_ATTR_CREATE_CQ_DBR_BUF_UMEM, }; enum mlx5_ib_reg_dmabuf_mr_attrs { -- 2.53.0