ixgbe: Preserve priority-tagged traffic with SR-IOV

VID 0 carries only 802.1p priority and does not identify VLAN
membership. Keep VFTA bit zero in the persistent PF shadow table so
reset and SR-IOV replay admit priority-tagged frames while VLAN
filtering is enabled.

In virtualization mode, also reserve VLVF slot zero and restore PF and
eligible VF pool memberships. A VFTA hit alone admits the tag globally
but does not deliver it to the correct pools.

This matches the priority-tag treatment in em/igb.

MFC after:	1 week

sys/dev/ixgbe/if_ix.c

@@ -2396,6 +2396,10 @@ ixgbe_iov_vlan_rebuild(struct ixgbe_softc *sc, bool promisc)
 		vf = &sc->vfs[i];
 		if ((vf->flags & IXGBE_VF_ACTIVE) == 0)
 			continue;
+		if (vf->default_vlan == 0 &&
+		    ixgbe_set_vfta(hw, 0, vf->pool, true, false) !=
+		    IXGBE_SUCCESS)
+			failures++;
 		for (word = 0; word < IXGBE_VFTA_SIZE; word++) {
 			bits = vf->vlans[word];
 			while (bits != 0) {
@@ -2410,6 +2414,8 @@ ixgbe_iov_vlan_rebuild(struct ixgbe_softc *sc, bool promisc)
 			}
 		}
 	}
+	if (ixgbe_set_vfta(hw, 0, sc->pool, true, false) != IXGBE_SUCCESS)
+		failures++;
 
 	/* Add the PF to shared entries, or every entry in promiscuous mode. */
 	for (i = 1; i < IXGBE_VLVF_ENTRIES; i++) {
@@ -2428,7 +2434,7 @@ ixgbe_iov_vlan_rebuild(struct ixgbe_softc *sc, bool promisc)
 		IXGBE_WRITE_REG(hw, IXGBE_VFTA(i), vfta[i]);
 	if (failures != 0)
 		device_printf(sc->dev,
-		    "VF VLAN restore failed for %d memberships\n", failures);
+		    "VLAN pool restore failed for %d memberships\n", failures);
 }
 
 static void
@@ -2481,6 +2487,9 @@ ixgbe_setup_vlan_hw_support(if_ctx_t ctx)
 			ctrl &= ~IXGBE_VLNCTRL_VME;
 	}
 
+	/* Always admit priority-tagged frames. */
+	sc->shadow_vfta[0] |= 1U;
+
 #ifdef PCI_IOV
 	if ((sc->feat_en & IXGBE_FEATURE_SRIOV) != 0) {
 		/*

sys/dev/ixgbe/if_sriov.c

@@ -408,8 +408,10 @@ ixgbe_vf_reset_vlan(struct ixgbe_softc *sc, struct ixgbe_vf *vf,
 	s32 error;
 
 	ixgbe_vf_clear_vlans(sc, vf, clear_hw);
-	error = IXGBE_SUCCESS;
-	if (vf->default_vlan != 0) {
+	if (vf->default_vlan == 0) {
+		/* VLAN 0 membership is implicit and not VF-removable. */
+		error = ixgbe_vf_vlan_hw_update(sc, vf, 0, true);
+	} else {
 		error = ixgbe_vf_vlan_hw_update(sc, vf, vf->default_vlan, true);
 		if (error == IXGBE_SUCCESS)
 			ixgbe_vf_vlan_record(vf, vf->default_vlan, true);

sys/dev/ixgbe/ix_txrx.c

@@ -469,9 +469,10 @@ ixgbe_isc_rxd_pkt_get(void *arg, if_rxd_info_t ri)
 		 * A PF-assigned port VLAN is stripped before a VF receives the
 		 * frame, but it is not one of the VLANs registered by the VF.
 		 * Do not expose that administrative tag to the VF's network
-		 * stack.  Locally registered trunk VLANs retain M_VLANTAG.
+		 * stack.  Priority tags and locally registered trunk VLANs retain
+		 * M_VLANTAG.
 		 */
-		if ((sc->feat_en & IXGBE_FEATURE_VF) == 0 ||
+		if ((sc->feat_en & IXGBE_FEATURE_VF) == 0 || vid == 0 ||
 		    (sc->shadow_vfta[vid >> 5] &
 		    (1U << (vid & 0x1f))) != 0) {
 			ri->iri_vtag = vtag;