net: hns3: fix for setting MTU

When setting MTU, actually what we do is configuring the max frame size
for the hardware. ETH_HLEN、ETH_FCS_LEN and VLAN_HLEN must need to be
considered. And the frame size which is less than the default value
should not be set to the hardware. Because in the hardware, the the max
frame size not only controls the RX packet size, but also controls the
TX packet size. the RX packets whose size are greater than the setting
value will be dropped.

This patch fixes the bug setting a error max frame size to hardware.

Fixes: 46a3df9f ("net: hns3: Add HNS3 Acceleration Engine & Compatibility Layer Support")
Signed-off-by: Fuyun Liang <liangfuyun1@huawei.com>
Signed-off-by: Peng Li <lipeng321@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/hisilicon/hns3/hns3pf/hclge_cmd.h

@@ -556,8 +556,6 @@ struct hclge_config_auto_neg_cmd {
 	u8      rsv[20];
 };
 
-#define HCLGE_MAC_MIN_MTU		64
-#define HCLGE_MAC_MAX_MTU		9728
 #define HCLGE_MAC_UPLINK_PORT		0x100
 
 struct hclge_config_max_frm_size_cmd {

drivers/net/ethernet/hisilicon/hns3/hns3pf/hclge_main.c

@@ -17,6 +17,7 @@
 #include <linux/netdevice.h>
 #include <linux/pci.h>
 #include <linux/platform_device.h>
+#include <linux/if_vlan.h>
 #include <net/rtnetlink.h>
 #include "hclge_cmd.h"
 #include "hclge_dcb.h"
@@ -4560,16 +4561,21 @@ static int hclge_set_mtu(struct hnae3_handle *handle, int new_mtu)
 	struct hclge_config_max_frm_size_cmd *req;
 	struct hclge_dev *hdev = vport->back;
 	struct hclge_desc desc;
+	int max_frm_size;
 	int ret;
 
-	if ((new_mtu < HCLGE_MAC_MIN_MTU) || (new_mtu > HCLGE_MAC_MAX_MTU))
+	max_frm_size = new_mtu + ETH_HLEN + ETH_FCS_LEN + VLAN_HLEN;
+
+	if (max_frm_size < HCLGE_MAC_MIN_FRAME ||
+	    max_frm_size > HCLGE_MAC_MAX_FRAME)
 		return -EINVAL;
 
-	hdev->mps = new_mtu;
+	max_frm_size = max(max_frm_size, HCLGE_MAC_DEFAULT_FRAME);
+
 	hclge_cmd_setup_basic_desc(&desc, HCLGE_OPC_CONFIG_MAX_FRM_SIZE, false);
 
 	req = (struct hclge_config_max_frm_size_cmd *)desc.data;
-	req->max_frm_size = cpu_to_le16(new_mtu);
+	req->max_frm_size = cpu_to_le16(max_frm_size);
 
 	ret = hclge_cmd_send(&hdev->hw, &desc, 1);
 	if (ret) {
@@ -4577,6 +4583,8 @@ static int hclge_set_mtu(struct hnae3_handle *handle, int new_mtu)
 		return ret;
 	}
 
+	hdev->mps = max_frm_size;
+
 	return 0;
 }
 

drivers/net/ethernet/hisilicon/hns3/hns3pf/hclge_main.h

@@ -101,6 +101,11 @@
 /* CMDQ register bits for RX event(=MBX event) */
 #define HCLGE_VECTOR0_RX_CMDQ_INT_B	1
 
+#define HCLGE_MAC_DEFAULT_FRAME \
+	(ETH_HLEN + ETH_FCS_LEN + VLAN_HLEN + ETH_DATA_LEN)
+#define HCLGE_MAC_MIN_FRAME		64
+#define HCLGE_MAC_MAX_FRAME		9728
+
 enum HCLGE_DEV_STATE {
 	HCLGE_STATE_REINITING,
 	HCLGE_STATE_DOWN,