MFC r291747

sfxge: [EF10] support RxQ scattering control

If, for example, a VF is configured to use a 1500 byte MTU, but the port
it is attached to is set to 9000 bytes, overlength frames can be received
by the VF. As Huntington scatters by default, these overlength packets
would be scattered across several descriptors, with all except the last
having the CONT bit set.

To avoid this, disable scatter when creating RXQs if the firmware
supports doing so, which all recent versions do. Then we only get
a single descriptor from an overlength frame. This will have the CONT
bit set to indicate it was truncated, so we can discard it.

Submitted by:   Mark Spender <mspender at solarflare.com>
Sponsored by:   Solarflare Communications, Inc.

4 files changed, 35 insertions, 12 deletions

diff --git a/sys/dev/sfxge/common/efx.h b/sys/dev/sfxge/common/efx.h
index 95d2f61..d33d478c 100644
--- a/sys/dev/sfxge/common/efx.h
+++ b/sys/dev/sfxge/common/efx.h
@@ -1174,6 +1174,7 @@ typedef struct efx_nic_cfg_s {
 	boolean_t               enc_hw_tx_insert_vlan_enabled;
 	/* Datapath firmware vadapter/vport/vswitch support */
 	boolean_t		enc_datapath_cap_evb;
+	boolean_t               enc_rx_disable_scatter_supported;
 	/* External port identifier */
 	uint8_t			enc_external_port;
 } efx_nic_cfg_t;
diff --git a/sys/dev/sfxge/common/hunt_ev.c b/sys/dev/sfxge/common/hunt_ev.c
index 71d85c5..f9fbc81 100644
--- a/sys/dev/sfxge/common/hunt_ev.c
+++ b/sys/dev/sfxge/common/hunt_ev.c
@@ -528,10 +528,14 @@ hunt_ev_rx(
 
 	if (EFX_QWORD_FIELD(*eqp, ESF_DZ_RX_CONT) != 0) {
 		/*
+		 * This may be part of a scattered frame, or it may be a
+		 * truncated frame if scatter is disabled on this RXQ.
+		 * Overlength frames can be received if e.g. a VF is configured
+		 * for 1500 MTU but connected to a port set to 9000 MTU
+		 * (see bug56567).
 		 * FIXME: There is not yet any driver that supports scatter on
 		 * Huntington.  Scatter support is required for OSX.
 		 */
-		EFSYS_ASSERT(0);
 		flags |= EFX_PKT_CONT;
 	}
 
diff --git a/sys/dev/sfxge/common/hunt_nic.c b/sys/dev/sfxge/common/hunt_nic.c
index 3fcaae5..b41eb40 100644
--- a/sys/dev/sfxge/common/hunt_nic.c
+++ b/sys/dev/sfxge/common/hunt_nic.c
@@ -920,6 +920,14 @@ hunt_get_datapath_caps(
 		encp->enc_rx_batching_enabled = B_FALSE;
 	}
 
+	/* Check if the firmware supports disabling scatter on RXQs */
+	if (MCDI_CMD_DWORD_FIELD(&datapath_capabilities,
+			    GET_CAPABILITIES_OUT_RX_DISABLE_SCATTER) == 1) {
+		encp->enc_rx_disable_scatter_supported = B_TRUE;
+	} else {
+		encp->enc_rx_disable_scatter_supported = B_FALSE;
+	}
+
 	return (0);
 
 fail2:
diff --git a/sys/dev/sfxge/common/hunt_rx.c b/sys/dev/sfxge/common/hunt_rx.c
index e173a23..6fdc747 100644
--- a/sys/dev/sfxge/common/hunt_rx.c
+++ b/sys/dev/sfxge/common/hunt_rx.c
@@ -46,7 +46,8 @@ efx_mcdi_init_rxq(
 	__in		uint32_t target_evq,
 	__in		uint32_t label,
 	__in		uint32_t instance,
-	__in		efsys_mem_t *esmp)
+	__in		efsys_mem_t *esmp,
+	__in		boolean_t disable_scatter)
 {
 	efx_mcdi_req_t req;
 	uint8_t payload[
@@ -71,12 +72,13 @@ efx_mcdi_init_rxq(
 	MCDI_IN_SET_DWORD(req, INIT_RXQ_IN_TARGET_EVQ, target_evq);
 	MCDI_IN_SET_DWORD(req, INIT_RXQ_IN_LABEL, label);
 	MCDI_IN_SET_DWORD(req, INIT_RXQ_IN_INSTANCE, instance);
-	MCDI_IN_POPULATE_DWORD_5(req, INIT_RXQ_IN_FLAGS,
-				    INIT_RXQ_IN_FLAG_BUFF_MODE, 0,
-				    INIT_RXQ_IN_FLAG_HDR_SPLIT, 0,
-				    INIT_RXQ_IN_FLAG_TIMESTAMP, 0,
-				    INIT_RXQ_IN_CRC_MODE, 0,
-				    INIT_RXQ_IN_FLAG_PREFIX, 1);
+	MCDI_IN_POPULATE_DWORD_6(req, INIT_RXQ_IN_FLAGS,
+			    INIT_RXQ_IN_FLAG_BUFF_MODE, 0,
+			    INIT_RXQ_IN_FLAG_HDR_SPLIT, 0,
+			    INIT_RXQ_IN_FLAG_TIMESTAMP, 0,
+			    INIT_RXQ_IN_CRC_MODE, 0,
+			    INIT_RXQ_IN_FLAG_PREFIX, 1,
+			    INIT_RXQ_IN_FLAG_DISABLE_SCATTER, disable_scatter);
 	MCDI_IN_SET_DWORD(req, INIT_RXQ_IN_OWNER_ID, 0);
 	MCDI_IN_SET_DWORD(req, INIT_RXQ_IN_PORT_ID, EVB_PORT_ID_ASSIGNED);
 
@@ -685,6 +687,7 @@ hunt_rx_qcreate(
 {
 	efx_nic_cfg_t *encp = &(enp->en_nic_cfg);
 	efx_rc_t rc;
+	boolean_t disable_scatter;
 
 	_NOTE(ARGUNUSED(erp))
 
@@ -704,14 +707,21 @@ hunt_rx_qcreate(
 		goto fail2;
 	}
 
+	/* Scatter can only be disabled if the firmware supports doing so */
+	if ((type != EFX_RXQ_TYPE_SCATTER) &&
+	    enp->en_nic_cfg.enc_rx_disable_scatter_supported) {
+		disable_scatter = B_TRUE;
+	} else {
+		disable_scatter = B_FALSE;
+	}
+
 	/*
-	 * FIXME: Siena code handles different queue types (default, header
-	 * split, scatter); we'll need to do something more here later, but
-	 * all that stuff is TBD for now.
+	 * Note: EFX_RXQ_TYPE_SPLIT_HEADER and EFX_RXQ_TYPE_SPLIT_PAYLOAD are
+	 * not supported here.
 	 */
 
 	if ((rc = efx_mcdi_init_rxq(enp, n, eep->ee_index, label, index,
-	    esmp)) != 0)
+	    esmp, disable_scatter)) != 0)
 		goto fail3;
 
 	erp->er_eep = eep;