net/sfc: fix MTU change to check Rx scatter consistency

Rx queue setup function checks configured MTU to make sure that
no oversized packets can be received. But a following call to
set MTU function might make this check irrelevant.

Add a function to check MTU size against Rx buffer size and
additional Rx queue info, including Rx scatter offload.

Fixes: e961cf425e02 ("net/sfc: support MTU change")
Cc: stable@dpdk.org

Signed-off-by: Igor Romanov <igor.romanov@oktetlabs.ru>
Signed-off-by: Andrew Rybchenko <arybchenko@solarflare.com>

drivers/net/sfc/sfc_ethdev.c

@@ -865,6 +865,34 @@ fail_inval:
 	return -rc;
 }
 
+static int
+sfc_check_scatter_on_all_rx_queues(struct sfc_adapter *sa, size_t pdu)
+{
+	struct sfc_adapter_shared * const sas = sfc_sa2shared(sa);
+	const efx_nic_cfg_t *encp = efx_nic_cfg_get(sa->nic);
+	boolean_t scatter_enabled;
+	const char *error;
+	unsigned int i;
+
+	for (i = 0; i < sas->rxq_count; i++) {
+		if ((sas->rxq_info[i].state & SFC_RXQ_INITIALIZED) == 0)
+			continue;
+
+		scatter_enabled = (sas->rxq_info[i].type_flags &
+				   EFX_RXQ_FLAG_SCATTER);
+
+		if (!sfc_rx_check_scatter(pdu, sa->rxq_ctrl[i].buf_size,
+					  encp->enc_rx_prefix_size,
+					  scatter_enabled, &error)) {
+			sfc_err(sa, "MTU check for RxQ %u failed: %s", i,
+				error);
+			return EINVAL;
+		}
+	}
+
+	return 0;
+}
+
 static int
 sfc_dev_set_mtu(struct rte_eth_dev *dev, uint16_t mtu)
 {
@@ -891,6 +919,10 @@ sfc_dev_set_mtu(struct rte_eth_dev *dev, uint16_t mtu)
 
 	sfc_adapter_lock(sa);
 
+	rc = sfc_check_scatter_on_all_rx_queues(sa, pdu);
+	if (rc != 0)
+		goto fail_check_scatter;
+
 	if (pdu != sa->port.pdu) {
 		if (sa->state == SFC_ADAPTER_STARTED) {
 			sfc_stop(sa);
@@ -927,6 +959,8 @@ fail_start:
 		sfc_err(sa, "cannot start with neither new (%u) nor old (%u) "
 			"PDU max size - port is stopped",
 			(unsigned int)pdu, (unsigned int)old_pdu);
+
+fail_check_scatter:
 	sfc_adapter_unlock(sa);
 
 fail_inval:

drivers/net/sfc/sfc_rx.c

@@ -360,6 +360,18 @@ sfc_efx_rx_qdesc_status(struct sfc_dp_rxq *dp_rxq, uint16_t offset)
 	return RTE_ETH_RX_DESC_UNAVAIL;
 }
 
+boolean_t
+sfc_rx_check_scatter(size_t pdu, size_t rx_buf_size, uint32_t rx_prefix_size,
+		     boolean_t rx_scatter_enabled, const char **error)
+{
+	if ((rx_buf_size < pdu + rx_prefix_size) && !rx_scatter_enabled) {
+		*error = "Rx scatter is disabled and RxQ mbuf pool object size is too small";
+		return B_FALSE;
+	}
+
+	return B_TRUE;
+}
+
 /** Get Rx datapath ops by the datapath RxQ handle */
 const struct sfc_dp_rx *
 sfc_dp_rx_by_dp_rxq(const struct sfc_dp_rxq *dp_rxq)
@@ -975,6 +987,7 @@ sfc_rx_qinit(struct sfc_adapter *sa, unsigned int sw_index,
 	struct sfc_dp_rx_qcreate_info info;
 	struct sfc_dp_rx_hw_limits hw_limits;
 	uint16_t rx_free_thresh;
+	const char *error;
 
 	memset(&hw_limits, 0, sizeof(hw_limits));
 	hw_limits.rxq_max_entries = sa->rxq_max_entries;
@@ -1005,10 +1018,11 @@ sfc_rx_qinit(struct sfc_adapter *sa, unsigned int sw_index,
 		goto fail_bad_conf;
 	}
 
-	if ((buf_size < sa->port.pdu + encp->enc_rx_prefix_size) &&
-	    (~offloads & DEV_RX_OFFLOAD_SCATTER)) {
-		sfc_err(sa, "Rx scatter is disabled and RxQ %u mbuf pool "
-			"object size is too small", sw_index);
+	if (!sfc_rx_check_scatter(sa->port.pdu, buf_size,
+				  encp->enc_rx_prefix_size,
+				  (offloads & DEV_RX_OFFLOAD_SCATTER),
+				  &error)) {
+		sfc_err(sa, "RxQ %u MTU check failed: %s", sw_index, error);
 		sfc_err(sa, "RxQ %u calculated Rx buffer size is %u vs "
 			"PDU size %u plus Rx prefix %u bytes",
 			sw_index, buf_size, (unsigned int)sa->port.pdu,

drivers/net/sfc/sfc_rx.h

@@ -142,6 +142,10 @@ void sfc_rx_hash_fini(struct sfc_adapter *sa);
 int sfc_rx_hf_rte_to_efx(struct sfc_adapter *sa, uint64_t rte,
 			 efx_rx_hash_type_t *efx);
 uint64_t sfc_rx_hf_efx_to_rte(struct sfc_rss *rss, efx_rx_hash_type_t efx);
+boolean_t sfc_rx_check_scatter(size_t pdu, size_t rx_buf_size,
+			       uint32_t rx_prefix_size,
+			       boolean_t rx_scatter_enabled,
+			       const char **error);
 
 #ifdef __cplusplus
 }