Re: [dpdk-dev] [PATCH v3] net/i40e: fix TSO pkt exceeds allowed buf size issue

[Ye Xiaolong <xiaolong.ye@intel.com>]

On 12/26, Xiaoyun Li wrote:
>Hardware limits that max buffer size per tx descriptor should be
>(16K-1)B. So when TSO enabled, the mbuf data size may exceed the
>limit and cause malicious behavior to the NIC. This patch fixes
>this issue by using more tx descs for this kind of large buffer.
>
>Fixes: 4861cde46116 ("i40e: new poll mode driver")
>Cc: stable@dpdk.org
>
>Signed-off-by: Xiaoyun Li <xiaoyun.li@intel.com>
>---
>v3:
> * Reused the existing macros to define I40E_MAX_DATA_PER_TXD
>v2:
> * Each pkt can have several segments so the needed tx descs should sum
> * all segments up.
>---
> drivers/net/i40e/i40e_rxtx.c | 45 +++++++++++++++++++++++++++++++++++-
> 1 file changed, 44 insertions(+), 1 deletion(-)
>
>diff --git a/drivers/net/i40e/i40e_rxtx.c b/drivers/net/i40e/i40e_rxtx.c
>index 17dc8c78f..bbdba39b3 100644
>--- a/drivers/net/i40e/i40e_rxtx.c
>+++ b/drivers/net/i40e/i40e_rxtx.c
>@@ -989,6 +989,24 @@ i40e_set_tso_ctx(struct rte_mbuf *mbuf, union i40e_tx_offload tx_offload)
> 	return ctx_desc;
> }
> 
>+/* HW requires that Tx buffer size ranges from 1B up to (16K-1)B. */
>+#define I40E_MAX_DATA_PER_TXD \
>+	(I40E_TXD_QW1_TX_BUF_SZ_MASK >> I40E_TXD_QW1_TX_BUF_SZ_SHIFT)
>+/* Calculate the number of TX descriptors needed for each pkt */
>+static inline uint16_t
>+i40e_calc_pkt_desc(struct rte_mbuf *tx_pkt)
>+{
>+	struct rte_mbuf *txd = tx_pkt;
>+	uint16_t count = 0;
>+
>+	while (txd != NULL) {
>+		count += DIV_ROUND_UP(txd->data_len, I40E_MAX_DATA_PER_TXD);
>+		txd = txd->next;
>+	}
>+
>+	return count;
>+}
>+
> uint16_t
> i40e_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts, uint16_t nb_pkts)
> {
>@@ -1046,8 +1064,15 @@ i40e_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts, uint16_t nb_pkts)
> 		 * The number of descriptors that must be allocated for
> 		 * a packet equals to the number of the segments of that
> 		 * packet plus 1 context descriptor if needed.
>+		 * Recalculate the needed tx descs when TSO enabled in case
>+		 * the mbuf data size exceeds max data size that hw allows
>+		 * per tx desc.
> 		 */
>-		nb_used = (uint16_t)(tx_pkt->nb_segs + nb_ctx);
>+		if (ol_flags & PKT_TX_TCP_SEG)
>+			nb_used = (uint16_t)(i40e_calc_pkt_desc(tx_pkt) +
>+					     nb_ctx);
>+		else
>+			nb_used = (uint16_t)(tx_pkt->nb_segs + nb_ctx);
> 		tx_last = (uint16_t)(tx_id + nb_used - 1);
> 
> 		/* Circular ring */
>@@ -1160,6 +1185,24 @@ i40e_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts, uint16_t nb_pkts)
> 			slen = m_seg->data_len;
> 			buf_dma_addr = rte_mbuf_data_iova(m_seg);
> 
>+			while ((ol_flags & PKT_TX_TCP_SEG) &&
>+				unlikely(slen > I40E_MAX_DATA_PER_TXD)) {
>+				txd->buffer_addr =
>+					rte_cpu_to_le_64(buf_dma_addr);
>+				txd->cmd_type_offset_bsz =
>+					i40e_build_ctob(td_cmd,
>+					td_offset, I40E_MAX_DATA_PER_TXD,
>+					td_tag);
>+
>+				buf_dma_addr += I40E_MAX_DATA_PER_TXD;
>+				slen -= I40E_MAX_DATA_PER_TXD;
>+
>+				txe->last_id = tx_last;
>+				tx_id = txe->next_id;
>+				txe = txn;
>+				txd = &txr[tx_id];
>+				txn = &sw_ring[txe->next_id];
>+			}
> 			PMD_TX_LOG(DEBUG, "mbuf: %p, TDD[%u]:\n"
> 				"buf_dma_addr: %#"PRIx64";\n"
> 				"td_cmd: %#x;\n"
>-- 
>2.17.1
>

Applied to dpdk-next-net-intel, Thanks.