RDMA/hns: Fix bug that caused srq creation to fail

[ Upstream commit 4772e03d ]

Due to the incorrect use of the seg and obj information, the position of
the mtt is calculated incorrectly, and the free space of the page is not
enough to store the entire mtt, resulting in access to the next page. This
patch fixes this problem.

 Unable to handle kernel paging request at virtual address ffff00006e3cd000
 ...
 Call trace:
  hns_roce_write_mtt+0x154/0x2f0 [hns_roce]
  hns_roce_buf_write_mtt+0xa8/0xd8 [hns_roce]
  hns_roce_create_srq+0x74c/0x808 [hns_roce]
  ib_create_srq+0x28/0xc8

Fixes: 0203b14c ("RDMA/hns: Unify the calculation for hem index in hip08")
Signed-off-by: chenglang <chenglang@huawei.com>
Signed-off-by: Lijun Ou <oulijun@huawei.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

drivers/infiniband/hw/hns/hns_roce_hem.c

@@ -745,6 +745,8 @@ void *hns_roce_table_find(struct hns_roce_dev *hr_dev,
 		idx_offset = (obj & (table->num_obj - 1)) % obj_per_chunk;
 		dma_offset = offset = idx_offset * table->obj_size;
 	} else {
+		u32 seg_size = 64; /* 8 bytes per BA and 8 BA per segment */
+
 		hns_roce_calc_hem_mhop(hr_dev, table, &mhop_obj, &mhop);
 		/* mtt mhop */
 		i = mhop.l0_idx;
@@ -756,8 +758,8 @@ void *hns_roce_table_find(struct hns_roce_dev *hr_dev,
 			hem_idx = i;
 
 		hem = table->hem[hem_idx];
-		dma_offset = offset = (obj & (table->num_obj - 1)) *
-				       table->obj_size % mhop.bt_chunk_size;
+		dma_offset = offset = (obj & (table->num_obj - 1)) * seg_size %
+				       mhop.bt_chunk_size;
 		if (mhop.hop_num == 2)
 			dma_offset = offset = 0;
 	}

drivers/infiniband/hw/hns/hns_roce_mr.c

@@ -707,7 +707,6 @@ static int hns_roce_write_mtt_chunk(struct hns_roce_dev *hr_dev,
 	struct hns_roce_hem_table *table;
 	dma_addr_t dma_handle;
 	__le64 *mtts;
-	u32 s = start_index * sizeof(u64);
 	u32 bt_page_size;
 	u32 i;
 
@@ -730,7 +729,8 @@ static int hns_roce_write_mtt_chunk(struct hns_roce_dev *hr_dev,
 		table = &hr_dev->mr_table.mtt_cqe_table;
 
 	mtts = hns_roce_table_find(hr_dev, table,
-				mtt->first_seg + s / hr_dev->caps.mtt_entry_sz,
+				mtt->first_seg +
+				start_index / HNS_ROCE_MTT_ENTRY_PER_SEG,
 				&dma_handle);
 	if (!mtts)
 		return -ENOMEM;