hw/mlx5/doorbell.c

0001 /*
0002  * Copyright (c) 2013-2015, Mellanox Technologies. All rights reserved.
0003  *
0004  * This software is available to you under a choice of one of two
0005  * licenses.  You may choose to be licensed under the terms of the GNU
0006  * General Public License (GPL) Version 2, available from the file
0007  * COPYING in the main directory of this source tree, or the
0008  * OpenIB.org BSD license below:
0009  *
0010  *     Redistribution and use in source and binary forms, with or
0011  *     without modification, are permitted provided that the following
0012  *     conditions are met:
0013  *
0014  *      - Redistributions of source code must retain the above
0015  *        copyright notice, this list of conditions and the following
0016  *        disclaimer.
0017  *
0018  *      - Redistributions in binary form must reproduce the above
0019  *        copyright notice, this list of conditions and the following
0020  *        disclaimer in the documentation and/or other materials
0021  *        provided with the distribution.
0022  *
0023  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
0024  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
0025  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
0026  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
0027  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
0028  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
0029  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
0030  * SOFTWARE.
0031  */
0032
0033 #include <linux/kref.h>
0034 #include <linux/slab.h>
0035 #include <linux/sched/mm.h>
0036 #include <rdma/ib_umem.h>
0037
0038 #include "mlx5_ib.h"
0039
0040 struct mlx5_ib_user_db_page {
0041     struct list_head    list;
0042     struct ib_umem         *umem;
0043     unsigned long       user_virt;
0044     int         refcnt;
0045     struct mm_struct    *mm;
0046 };
0047
0048 int mlx5_ib_db_map_user(struct mlx5_ib_ucontext *context, unsigned long virt,
0049             struct mlx5_db *db)
0050 {
0051     struct mlx5_ib_user_db_page *page;
0052     int err = 0;
0053
0054     mutex_lock(&context->db_page_mutex);
0055
0056     list_for_each_entry(page, &context->db_page_list, list)
0057         if ((current->mm == page->mm) &&
0058             (page->user_virt == (virt & PAGE_MASK)))
0059             goto found;
0060
0061     page = kmalloc(sizeof(*page), GFP_KERNEL);
0062     if (!page) {
0063         err = -ENOMEM;
0064         goto out;
0065     }
0066
0067     page->user_virt = (virt & PAGE_MASK);
0068     page->refcnt    = 0;
0069     page->umem = ib_umem_get(context->ibucontext.device, virt & PAGE_MASK,
0070                  PAGE_SIZE, 0);
0071     if (IS_ERR(page->umem)) {
0072         err = PTR_ERR(page->umem);
0073         kfree(page);
0074         goto out;
0075     }
0076     mmgrab(current->mm);
0077     page->mm = current->mm;
0078
0079     list_add(&page->list, &context->db_page_list);
0080
0081 found:
0082     db->dma = sg_dma_address(page->umem->sgt_append.sgt.sgl) +
0083           (virt & ~PAGE_MASK);
0084     db->u.user_page = page;
0085     ++page->refcnt;
0086
0087 out:
0088     mutex_unlock(&context->db_page_mutex);
0089
0090     return err;
0091 }
0092
0093 void mlx5_ib_db_unmap_user(struct mlx5_ib_ucontext *context, struct mlx5_db *db)
0094 {
0095     mutex_lock(&context->db_page_mutex);
0096
0097     if (!--db->u.user_page->refcnt) {
0098         list_del(&db->u.user_page->list);
0099         mmdrop(db->u.user_page->mm);
0100         ib_umem_release(db->u.user_page->umem);
0101         kfree(db->u.user_page);
0102     }
0103
0104     mutex_unlock(&context->db_page_mutex);
0105 }