net: hns3: Fix for VF mailbox cannot receiving PF response

When the VF frequently switches the CMDQ interrupt, if the CMDQ_SRC is not
cleared, the VF will not receive the new PF response after the interrupt
is re-enabled, the corresponding log is as follows:

[  317.482222] hns3 0000:00:03.0: VF could not get mbx resp(=0) from PF
in 500 tries
[  317.483137] hns3 0000:00:03.0: VF request to get tqp info from PF
failed -5

This patch fixes this problem by clearing CMDQ_SRC before enabling
interrupt and syncing pending IRQ handlers after disabling interrupt.

Fixes: e2cb1dec ("net: hns3: Add HNS3 VF HCL(Hardware Compatibility Layer) Support")
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>

drivers/net/ethernet/hisilicon/hns3/hns3vf/hclgevf_main.c

@@ -1565,6 +1565,8 @@ static int hclgevf_misc_irq_init(struct hclgevf_dev *hdev)
 		return ret;
 	}
 
+	hclgevf_clear_event_cause(hdev, 0);
+
 	/* enable misc. vector(vector 0) */
 	hclgevf_enable_vector(&hdev->misc_vector, true);
 
@@ -1575,6 +1577,7 @@ static void hclgevf_misc_irq_uninit(struct hclgevf_dev *hdev)
 {
 	/* disable misc vector(vector 0) */
 	hclgevf_enable_vector(&hdev->misc_vector, false);
+	synchronize_irq(hdev->misc_vector.vector_irq);
 	free_irq(hdev->misc_vector.vector_irq, hdev);
 	hclgevf_free_vector(hdev, 0);
 }