ixgbe: Preserve the full VF RSS domain in the shared RETA

The 82599 and X540 share the global RSS redirection table between the
PF and its VFs.  Programming that table from the PF queue count
prevents a VF from using queue indices absent from the PF layout.  A
one-queue PF consequently directs every flow for a two- or four-queue
VF to queue zero.

Program at least four queue indices while SR-IOV is active.  Each pool
PSRTYPE.RQPL field masks the shared table to the queue subset available
to that function, so the PF can continue using fewer queues.

MFC after:	2 weeks

1 files changed, 17 insertions, 5 deletions

diff --git a/sys/dev/ixgbe/if_ix.c b/sys/dev/ixgbe/if_ix.c
index 9a59ce6b4fe8..8a80f15c77d8 100644
--- a/sys/dev/ixgbe/if_ix.c
+++ b/sys/dev/ixgbe/if_ix.c
@@ -661,7 +661,7 @@ ixgbe_initialize_rss_mapping(struct ixgbe_softc *sc)
 {
 	struct ixgbe_hw *hw = &sc->hw;
 	u32 reta = 0, mrqc, rss_key[10];
-	int queue_id, table_size, index_mult;
+	int queue_id, reta_queues, table_size, index_mult;
 	int i, j;
 	u32 rss_hash_config;
 
@@ -690,19 +690,31 @@ ixgbe_initialize_rss_mapping(struct ixgbe_softc *sc)
 		break;
 	}
 
+	/*
+	 * The global RETA is shared by the PF and VFs on 82599 and X540.
+	 * Program all four queue indices while SR-IOV is active so a VF can
+	 * use its full queue grant even when the PF uses fewer queues.
+	 * PSRTYPE.RQPL limits the subset selected within each pool.
+	 */
+	reta_queues = sc->num_rx_queues;
+#ifdef PCI_IOV
+	if (sc->iov_mode != IXGBE_NO_VM)
+		reta_queues = MAX(reta_queues, 4);
+#endif
+
 	/* Set up the redirection table */
 	for (i = 0, j = 0; i < table_size; i++, j++) {
-		if (j == sc->num_rx_queues)
+		if (j == reta_queues)
 			j = 0;
 
 		if (sc->feat_en & IXGBE_FEATURE_RSS) {
 			/*
 			 * Fetch the RSS bucket id for the given indirection
-			 * entry. Cap it at the number of configured buckets
-			 * (which is num_rx_queues.)
+			 * entry.  Cap it at the number of queue indices that must
+			 * be represented in the shared table.
 			 */
 			queue_id = rss_get_indirection_to_bucket(i);
-			queue_id = queue_id % sc->num_rx_queues;
+			queue_id = queue_id % reta_queues;
 		} else
 			queue_id = (j * index_mult);