[dpdk-stable] [PATCH] net/iavf: fix wrong Tx context descriptor

[beilei.xing@intel.com]

From: Beilei Xing <beilei.xing@intel.com>

The QW0 of Tx context descriptor should be reset to 0, otherwise the
previous hardware writeback value may polute the next context descriptor
write.

Fixes: a2b29a7733ef ("net/avf: enable basic Rx Tx")
Cc: stable@dpdk.org

Signed-off-by: Qi Zhang <qi.z.zhang@intel.com>
Signed-off-by: Beilei Xing <beilei.xing@intel.com>
---
 drivers/net/iavf/iavf_rxtx.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/net/iavf/iavf_rxtx.c b/drivers/net/iavf/iavf_rxtx.c
index 74b5ab5bde..6a713df828 100644
--- a/drivers/net/iavf/iavf_rxtx.c
+++ b/drivers/net/iavf/iavf_rxtx.c
@@ -2245,6 +2245,11 @@ iavf_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts, uint16_t nb_pkts)
 				(volatile struct iavf_tx_context_desc *)
 							&txr[tx_id];
 
+			/* clear QW0 or the previous writeback value
+			 * may impact next write
+			 */
+			*(volatile uint64_t *)ctx_txd = 0;
+
 			txn = &sw_ring[txe->next_id];
 			RTE_MBUF_PREFETCH_TO_FREE(txn->mbuf);
 			if (txe->mbuf) {
-- 
2.26.2