[PATCH v2] net/sfc: stop misuse of Rx ingress m-port metadata on EF100
Andrew Rybchenko
andrew.rybchenko at oktetlabs.ru
Sun Mar 12 08:59:21 CET 2023
On 3/10/23 20:01, Ivan Malov wrote:
> 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 at dpdk.org
>
> Signed-off-by: Ivan Malov <ivan.malov at arknetworks.am>
> Reviewed-by: Andy Moreton <amoreton at xilinx.com>
Better now, but I still have a question. See below.
> ---
> v2: address community review notes
>
> drivers/net/sfc/sfc_dp_rx.h | 1 +
> drivers/net/sfc/sfc_ef100_rx.c | 9 +++++----
> drivers/net/sfc/sfc_rx.c | 3 +++
> 3 files changed, 9 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..09e5a271d5 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;
> @@ -889,10 +892,8 @@ sfc_ef100_rx_qstart(struct sfc_dp_rxq *dp_rxq, unsigned int evq_read_ptr,
> else
> rxq->flags &= ~SFC_EF100_RXQ_USER_MARK;
>
> - if ((unsup_rx_prefix_fields &
> - (1U << EFX_RX_PREFIX_FIELD_INGRESS_MPORT)) == 0)
> - rxq->flags |= SFC_EF100_RXQ_INGRESS_MPORT;
> - else
> + if (unsup_rx_prefix_fields &
> + (1U << EFX_RX_PREFIX_FIELD_INGRESS_MPORT))
> rxq->flags &= ~SFC_EF100_RXQ_INGRESS_MPORT;
Shouldn't we fail here instead? Basically it means that the
representors proxy cannot do its job.
EFX_RXQ_FLAG_INGRESS_MPORT is requested for representors
proxy Rx queue only.
>
> if ((unsup_rx_prefix_fields &
> 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,
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