Re: [dpdk-dev] [PATCH v2] net/i40e: fix TSO pkt exceeds allowed buf size issue

["Li, Xiaoyun" <xiaoyun.li@intel.com>]

Sure. Will fix them in v3. Thanks.

> -----Original Message-----
> From: Zhang, Qi Z
> Sent: Thursday, December 26, 2019 09:51
> To: Li, Xiaoyun <xiaoyun.li@intel.com>; Xing, Beilei <beilei.xing@intel.com>; Ye,
> Xiaolong <xiaolong.ye@intel.com>; Loftus, Ciara <ciara.loftus@intel.com>;
> dev@dpdk.org
> Cc: stable@dpdk.org
> Subject: RE: [PATCH v2] net/i40e: fix TSO pkt exceeds allowed buf size issue
> 
> HI Xiaoyun:
> 
> 	Overall looks good to me, some minor capture inline
> 
> 
> > -----Original Message-----
> > From: Li, Xiaoyun <xiaoyun.li@intel.com>
> > Sent: Wednesday, December 25, 2019 4:56 PM
> > To: Zhang, Qi Z <qi.z.zhang@intel.com>; Xing, Beilei
> > <beilei.xing@intel.com>; Ye, Xiaolong <xiaolong.ye@intel.com>; Loftus,
> > Ciara <ciara.loftus@intel.com>; dev@dpdk.org
> > Cc: Li, Xiaoyun <xiaoyun.li@intel.com>; stable@dpdk.org
> > Subject: [PATCH v2] net/i40e: fix TSO pkt exceeds allowed buf size
> > issue
> >
> > 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 behaviour to the NIC. This patch fixes this issue
> > by using more tx
> 
> Behavior
> 
> > 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>
> > ---
> > v2:
> >  * Each pkt can have several segments so the needed tx descs should
> > sum
> >  * all segments up.
> > ---
> >  drivers/net/i40e/i40e_rxtx.c | 44
> > +++++++++++++++++++++++++++++++++++-
> >  1 file changed, 43 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/net/i40e/i40e_rxtx.c
> > b/drivers/net/i40e/i40e_rxtx.c index
> > 17dc8c78f..ce95d8c20 100644
> > --- a/drivers/net/i40e/i40e_rxtx.c
> > +++ b/drivers/net/i40e/i40e_rxtx.c
> > @@ -989,6 +989,23 @@ 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	(16 * 1024 - 1)
> 
> Since this is limited by the 14 bit buffer size on Rx descriptor.
> 
> Is it better to reuse exist macro to define the max buf size?
> 
> #define I40E_MAX_DATA_PER_TXD \
> 	I40E_TXD_QW1_TX_BUF_SZ_MASK >>
> I40E_TXD_QW1_TX_BUF_SZ_SHIFT
> 
> Regards
> Qi
> 
> > +/* 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 +1063,15 @@ 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 +1184,24 @@ 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