virtio: Support non-legacy network device and queue

The non-legacy interface always defines num_buffers in the header,
regardless of whether VIRTIO_NET_F_MRG_RXBUF, just leaving it unused. We
also need to ensure our virtqueue doesn't filter out VIRTIO_F_VERSION_1
during negotiation, as it supports non-legacy transports just fine. This
fixes network packet transmission on TinyEMU.

Reviewed by:	br, brooks (mentor), jhb (mentor)
Approved by:	br, brooks (mentor), jhb (mentor)
Differential Revision:	https://reviews.freebsd.org/D25132

4 files changed, 20 insertions, 8 deletions

diff --git a/sys/dev/virtio/network/if_vtnet.c b/sys/dev/virtio/network/if_vtnet.c
index 9c5ed44d6fc3..570528738ee6 100644
--- a/sys/dev/virtio/network/if_vtnet.c
+++ b/sys/dev/virtio/network/if_vtnet.c
@@ -640,10 +640,13 @@ vtnet_setup_features(struct vtnet_softc *sc)
 		sc->vtnet_flags |= VTNET_FLAG_MAC;
 	}
 
-	if (virtio_with_feature(dev, VIRTIO_NET_F_MRG_RXBUF)) {
+	if (virtio_with_feature(dev, VIRTIO_NET_F_MRG_RXBUF))
 		sc->vtnet_flags |= VTNET_FLAG_MRG_RXBUFS;
+
+	if (virtio_with_feature(dev, VIRTIO_NET_F_MRG_RXBUF) ||
+	    virtio_with_feature(dev, VIRTIO_F_VERSION_1))
 		sc->vtnet_hdr_size = sizeof(struct virtio_net_hdr_mrg_rxbuf);
-	} else
+	else
 		sc->vtnet_hdr_size = sizeof(struct virtio_net_hdr);
 
 	if (sc->vtnet_flags & VTNET_FLAG_MRG_RXBUFS)
@@ -1459,9 +1462,10 @@ vtnet_rxq_enqueue_buf(struct vtnet_rxq *rxq, struct mbuf *m)
 
 	sglist_reset(sg);
 	if ((sc->vtnet_flags & VTNET_FLAG_MRG_RXBUFS) == 0) {
-		MPASS(sc->vtnet_hdr_size == sizeof(struct virtio_net_hdr));
+		MPASS(sc->vtnet_hdr_size == sizeof(rxhdr->vrh_uhdr.hdr) ||
+		    sc->vtnet_hdr_size == sizeof(rxhdr->vrh_uhdr.mhdr));
 		rxhdr = (struct vtnet_rx_header *) mdata;
-		sglist_append(sg, &rxhdr->vrh_hdr, sc->vtnet_hdr_size);
+		sglist_append(sg, &rxhdr->vrh_uhdr, sc->vtnet_hdr_size);
 		offset = sizeof(struct vtnet_rx_header);
 	} else
 		offset = 0;
diff --git a/sys/dev/virtio/network/if_vtnetvar.h b/sys/dev/virtio/network/if_vtnetvar.h
index e2e1f3362360..dae955b1228c 100644
--- a/sys/dev/virtio/network/if_vtnetvar.h
+++ b/sys/dev/virtio/network/if_vtnetvar.h
@@ -219,15 +219,20 @@ struct vtnet_softc {
  * When mergeable buffers are not negotiated, the vtnet_rx_header structure
  * below is placed at the beginning of the mbuf data. Use 4 bytes of pad to
  * both keep the VirtIO header and the data non-contiguous and to keep the
- * frame's payload 4 byte aligned.
+ * frame's payload 4 byte aligned. Note that non-legacy drivers still want
+ * room for a full mergeable buffer header.
  *
  * When mergeable buffers are negotiated, the host puts the VirtIO header in
  * the beginning of the first mbuf's data.
  */
 #define VTNET_RX_HEADER_PAD	4
 struct vtnet_rx_header {
-	struct virtio_net_hdr	vrh_hdr;
-	char			vrh_pad[VTNET_RX_HEADER_PAD];
+	union {
+		struct virtio_net_hdr		hdr;
+		struct virtio_net_hdr_mrg_rxbuf	mhdr;
+	} vrh_uhdr;
+
+	char	vrh_pad[VTNET_RX_HEADER_PAD];
 } __packed;
 
 /*
@@ -296,7 +301,8 @@ CTASSERT(sizeof(struct vtnet_mac_filter) <= PAGE_SIZE);
      VIRTIO_NET_F_MRG_RXBUF		| \
      VIRTIO_NET_F_MQ			| \
      VIRTIO_RING_F_EVENT_IDX		| \
-     VIRTIO_RING_F_INDIRECT_DESC)
+     VIRTIO_RING_F_INDIRECT_DESC	| \
+     VIRTIO_F_VERSION_1)
 
 /*
  * The VIRTIO_NET_F_HOST_TSO[46] features permit us to send the host
diff --git a/sys/dev/virtio/virtio.c b/sys/dev/virtio/virtio.c
index 0b574b74757e..aa58a47678ac 100644
--- a/sys/dev/virtio/virtio.c
+++ b/sys/dev/virtio/virtio.c
@@ -79,6 +79,7 @@ static struct virtio_feature_desc virtio_common_feature_desc[] = {
 	{ VIRTIO_RING_F_INDIRECT_DESC,	"RingIndirect"	},
 	{ VIRTIO_RING_F_EVENT_IDX,	"EventIdx"	},
 	{ VIRTIO_F_BAD_FEATURE,		"BadFeature"	},
+	{ VIRTIO_F_VERSION_1,		"Version1"	},
 
 	{ 0, NULL }
 };
diff --git a/sys/dev/virtio/virtqueue.c b/sys/dev/virtio/virtqueue.c
index e23d4d25c47f..0273c2ad005b 100644
--- a/sys/dev/virtio/virtqueue.c
+++ b/sys/dev/virtio/virtqueue.c
@@ -142,6 +142,7 @@ virtqueue_filter_features(uint64_t features)
 	mask = (1 << VIRTIO_TRANSPORT_F_START) - 1;
 	mask |= VIRTIO_RING_F_INDIRECT_DESC;
 	mask |= VIRTIO_RING_F_EVENT_IDX;
+	mask |= VIRTIO_F_VERSION_1;
 
 	return (features & mask);
 }