RDMA/hns: Fix the overflow risk of hem_list_calc_ba_range()

The max value of 'unit' and 'hop_num' is 2^24 and 2, so the value of
'step' may exceed the range of u32. Change the type of 'step' to u64.

Fixes: 38389eaa ("RDMA/hns: Add mtr support for mixed multihop addressing")
Signed-off-by: wenglianfa <wenglianfa@huawei.com>
Signed-off-by: Junxian Huang <huangjunxian6@hisilicon.com>
Link: https://patch.msgid.link/20240906093444.3571619-5-huangjunxian6@hisilicon.comSigned-off-by: Leon Romanovsky <leon@kernel.org>

drivers/infiniband/hw/hns/hns_roce_hem.c

@@ -1041,9 +1041,9 @@ static bool hem_list_is_bottom_bt(int hopnum, int bt_level)
  * @bt_level: base address table level
  * @unit: ba entries per bt page
  */
-static u32 hem_list_calc_ba_range(int hopnum, int bt_level, int unit)
+static u64 hem_list_calc_ba_range(int hopnum, int bt_level, int unit)
 {
-	u32 step;
+	u64 step;
 	int max;
 	int i;
 
@@ -1079,7 +1079,7 @@ int hns_roce_hem_list_calc_root_ba(const struct hns_roce_buf_region *regions,
 {
 	struct hns_roce_buf_region *r;
 	int total = 0;
-	int step;
+	u64 step;
 	int i;
 
 	for (i = 0; i < region_cnt; i++) {
@@ -1110,7 +1110,7 @@ static int hem_list_alloc_mid_bt(struct hns_roce_dev *hr_dev,
 	int ret = 0;
 	int max_ofs;
 	int level;
-	u32 step;
+	u64 step;
 	int end;
 
 	if (hopnum <= 1)
@@ -1147,7 +1147,7 @@ static int hem_list_alloc_mid_bt(struct hns_roce_dev *hr_dev,
 		}
 
 		start_aligned = (distance / step) * step + r->offset;
-		end = min_t(int, start_aligned + step - 1, max_ofs);
+		end = min_t(u64, start_aligned + step - 1, max_ofs);
 		cur = hem_list_alloc_item(hr_dev, start_aligned, end, unit,
 					  true);
 		if (!cur) {
@@ -1235,7 +1235,7 @@ static int setup_middle_bt(struct hns_roce_dev *hr_dev, void *cpu_base,
 	struct hns_roce_hem_item *hem, *temp_hem;
 	int total = 0;
 	int offset;
-	int step;
+	u64 step;
 
 	step = hem_list_calc_ba_range(r->hopnum, 1, unit);
 	if (step < 1)