[PATCH v3] net/sfc: stop misuse of Rx ingress m-port metadata on EF100

[Ivan Malov <ivan.malov@arknetworks.am>]

The driver supports representor functionality. In it,
packets coming from VFs to the dedicated back-end Rx
queue get demultiplexed into front-end Rx queues of
representor ethdevs as per the per-packet metadata
indicating logical HW ingress ports. On transmit,
packets are provided with symmetrical metadata
by front-end Tx queues, and the back-end queue
transforms the data into so-called Tx override
descriptors. These let the packets bypass flow
lookup and go directly to the represented VFs.

However, in the Rx part, the driver extracts
the said metadata on every HW Rx queue, that
is, not just on the one used by representors.
Doing so leads to a buggy behaviour. It is
revealed by operating testpmd as follows:

dpdk-testpmd -a 0000:c6:00.0 -a 0000:c6:00.1 -- -i

testpmd> flow create 0 transfer pattern port_representor \
 port_id is 0 / end actions port_representor port_id 1 / end
Flow rule #0 created

testpmd> set fwd io
testpmd> start tx_first

testpmd> flow destroy 0 rule 0
Flow rule #0 destroyed

testpmd> stop

  ---------------------- Forward statistics for port 0  -----------------
  RX-packets: 19196498       RX-dropped: 0             RX-total: 19196498
  TX-packets: 19196535       TX-dropped: 0             TX-total: 19196535
  -----------------------------------------------------------------------

  ---------------------- Forward statistics for port 1  -----------------
  RX-packets: 19196503       RX-dropped: 0             RX-total: 19196503
  TX-packets: 19196530       TX-dropped: 0             TX-total: 19196530
  -----------------------------------------------------------------------

In this scenario, two physical functions of the adapter
do not have any corresponding "back-to-back" forwarder
on peer host. Packets transmitted from port 0 can only
be forwarded to port 1 by means of a special flow rule.

The flow rule indeed works, but destroying it does not
stop forwarding. Port statistics carry on incrementing.

Also, it is apparent that forwarding in the opposite
direction must not have worked in this case as the
flow is meant to target only one of the directions.

Because of the bug, the first 32 mbufs received
as a result of the flow rule operation have the
said metadata present. In io mode, testpmd does
not tamper with mbufs and passes them directly
to transmit path, so this data remains in them
instructing the PMD to override destinations
of the packets via Tx option descriptors.

Expected behaviour is as follows:

  ---------------------- Forward statistics for port 0  -----------------
  RX-packets: 0              RX-dropped: 0             RX-total: 0
  TX-packets: 15787496       TX-dropped: 0             TX-total: 15787496
  -----------------------------------------------------------------------

  ---------------------- Forward statistics for port 1  -----------------
  RX-packets: 15787464       RX-dropped: 0             RX-total: 15787464
  TX-packets: 32             TX-dropped: 0             TX-total: 32
  -----------------------------------------------------------------------

These figures show the rule work only for one direction.
Also, removing the flow shall cause forwarding to cease.

Provided patch fixes the bug accordingly.

Fixes: d0f981a3efd8 ("net/sfc: handle ingress mport in EF100 Rx prefix")
Cc: stable@dpdk.org

Signed-off-by: Ivan Malov <ivan.malov@arknetworks.am>
Reviewed-by: Andy Moreton <amoreton@xilinx.com>
---
v3: extra rework after review feedback
v2: address community review notes

 drivers/net/sfc/sfc_dp_rx.h    |  1 +
 drivers/net/sfc/sfc_ef100_rx.c | 18 ++++++++++++++----
 drivers/net/sfc/sfc_rx.c       |  3 +++
 3 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/drivers/net/sfc/sfc_dp_rx.h b/drivers/net/sfc/sfc_dp_rx.h
index 246adbd87c..8a504bdcf1 100644
--- a/drivers/net/sfc/sfc_dp_rx.h
+++ b/drivers/net/sfc/sfc_dp_rx.h
@@ -69,6 +69,7 @@ struct sfc_dp_rx_qcreate_info {
 	/** Receive queue flags initializer */
 	unsigned int		flags;
 #define SFC_RXQ_FLAG_RSS_HASH	0x1
+#define SFC_RXQ_FLAG_INGRESS_MPORT	0x2
 
 	/** Rx queue size */
 	unsigned int		rxq_entries;
diff --git a/drivers/net/sfc/sfc_ef100_rx.c b/drivers/net/sfc/sfc_ef100_rx.c
index b7e3397f77..e323156a26 100644
--- a/drivers/net/sfc/sfc_ef100_rx.c
+++ b/drivers/net/sfc/sfc_ef100_rx.c
@@ -823,6 +823,9 @@ sfc_ef100_rx_qcreate(uint16_t port_id, uint16_t queue_id,
 	if (rxq->nic_dma_info->nb_regions > 0)
 		rxq->flags |= SFC_EF100_RXQ_NIC_DMA_MAP;
 
+	if (info->flags & SFC_RXQ_FLAG_INGRESS_MPORT)
+		rxq->flags |= SFC_EF100_RXQ_INGRESS_MPORT;
+
 	sfc_ef100_rx_debug(rxq, "RxQ doorbell is %p", rxq->doorbell);
 
 	*dp_rxqp = &rxq->dp;
@@ -889,11 +892,18 @@ sfc_ef100_rx_qstart(struct sfc_dp_rxq *dp_rxq, unsigned int evq_read_ptr,
 	else
 		rxq->flags &= ~SFC_EF100_RXQ_USER_MARK;
 
+
+	/*
+	 * At the moment, this feature is used only
+	 * by the representor proxy Rx queue and is
+	 * essential for representor support, so if
+	 * it has been requested but is unsupported,
+	 * point this inconsistency out to the user.
+	 */
 	if ((unsup_rx_prefix_fields &
-	     (1U << EFX_RX_PREFIX_FIELD_INGRESS_MPORT)) == 0)
-		rxq->flags |= SFC_EF100_RXQ_INGRESS_MPORT;
-	else
-		rxq->flags &= ~SFC_EF100_RXQ_INGRESS_MPORT;
+	     (1U << EFX_RX_PREFIX_FIELD_INGRESS_MPORT)) &&
+	    (rxq->flags & SFC_EF100_RXQ_INGRESS_MPORT))
+		return ENOTSUP;
 
 	if ((unsup_rx_prefix_fields &
 	     (1U << EFX_RX_PREFIX_FIELD_VLAN_STRIP_TCI)) == 0)
diff --git a/drivers/net/sfc/sfc_rx.c b/drivers/net/sfc/sfc_rx.c
index aae815a653..7401615362 100644
--- a/drivers/net/sfc/sfc_rx.c
+++ b/drivers/net/sfc/sfc_rx.c
@@ -1242,6 +1242,9 @@ sfc_rx_qinit(struct sfc_adapter *sa, sfc_sw_index_t sw_index,
 	else
 		rxq_info->rxq_flags = 0;
 
+	if (rxq_info->type_flags & EFX_RXQ_FLAG_INGRESS_MPORT)
+		rxq_info->rxq_flags |= SFC_RXQ_FLAG_INGRESS_MPORT;
+
 	rxq->buf_size = buf_size;
 
 	rc = sfc_dma_alloc(sa, "rxq", sw_index, EFX_NIC_DMA_ADDR_RX_RING,
-- 
2.17.1