From: Xi Wang <wangxi11@huawei.com>
Date: Fri, 25 May 2018 19:43:00 +0100
Subject: net: hns3: Fix for PF mailbox receving unknown message
Patch-mainline: v4.18-rc1
Git-commit: 7c4bfcb0556bc8e1cd86b25db0a5058b49f5a085
References: bsc#1104353 FATE#326415

Before the firmware updates the crq's tail pointer, if the PF driver
reads the data in the crq, the data may be incomplete at this time,
which will lead to the driver read an unknown message.

This patch fixes it by checking if crq is not empty before reading the
message.

Fixes: c1a81619d73a ("net: hns3: Add mailbox interrupt handling to PF driver")
Signed-off-by: Xi Wang <wangxi11@huawei.com>
Signed-off-by: Peng Li <lipeng321@huawei.com>
Signed-off-by: Salil Mehta <salil.mehta@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/net/ethernet/hisilicon/hns3/hns3pf/hclge_mbx.c |   23 ++++++++++++++---
 1 file changed, 20 insertions(+), 3 deletions(-)

--- a/drivers/net/ethernet/hisilicon/hns3/hns3pf/hclge_mbx.c
+++ b/drivers/net/ethernet/hisilicon/hns3/hns3pf/hclge_mbx.c
@@ -382,6 +382,13 @@ static void hclge_reset_vf(struct hclge_
 	hclge_func_reset_cmd(hdev, mbx_req->mbx_src_vfid);
 }
 
+static bool hclge_cmd_crq_empty(struct hclge_hw *hw)
+{
+	u32 tail = hclge_read_dev(hw, HCLGE_NIC_CRQ_TAIL_REG);
+
+	return tail == hw->cmq.crq.next_to_use;
+}
+
 void hclge_mbx_handler(struct hclge_dev *hdev)
 {
 	struct hclge_cmq_ring *crq = &hdev->hw.cmq.crq;
@@ -390,12 +397,23 @@ void hclge_mbx_handler(struct hclge_dev
 	struct hclge_desc *desc;
 	int ret, flag;
 
-	flag = le16_to_cpu(crq->desc[crq->next_to_use].flag);
 	/* handle all the mailbox requests in the queue */
-	while (hnae_get_bit(flag, HCLGE_CMDQ_RX_OUTVLD_B)) {
+	while (!hclge_cmd_crq_empty(&hdev->hw)) {
 		desc = &crq->desc[crq->next_to_use];
 		req = (struct hclge_mbx_vf_to_pf_cmd *)desc->data;
 
+		flag = le16_to_cpu(crq->desc[crq->next_to_use].flag);
+		if (unlikely(!hnae_get_bit(flag, HCLGE_CMDQ_RX_OUTVLD_B))) {
+			dev_warn(&hdev->pdev->dev,
+				 "dropped invalid mailbox message, code = %d\n",
+				 req->msg[0]);
+
+			/* dropping/not processing this invalid message */
+			crq->desc[crq->next_to_use].flag = 0;
+			hclge_mbx_ring_ptr_move_crq(crq);
+			continue;
+		}
+
 		vport = &hdev->vport[req->mbx_src_vfid];
 
 		switch (req->msg[0]) {
@@ -470,7 +488,6 @@ void hclge_mbx_handler(struct hclge_dev
 		}
 		crq->desc[crq->next_to_use].flag = 0;
 		hclge_mbx_ring_ptr_move_crq(crq);
-		flag = le16_to_cpu(crq->desc[crq->next_to_use].flag);
 	}
 
 	/* Write back CMDQ_RQ header pointer, M7 need this pointer */