Add a configurable workaround for a bug in qemu < 2.0 that prevented VLANs

from working.

2 files changed, 19 insertions, 9 deletions

diff --git a/share/man/man4/vio.4 b/share/man/man4/vio.4
index a1c14d7aaa6..a4135d5fb92 100644
--- a/share/man/man4/vio.4
+++ b/share/man/man4/vio.4
@@ -1,4 +1,4 @@
-.\"     $OpenBSD: vio.4,v 1.10 2014/05/09 14:44:56 sf Exp $
+.\"     $OpenBSD: vio.4,v 1.11 2014/06/17 19:46:13 sf Exp $
 .\"
 .\" Copyright (c) 2012 Stefan Fritsch <sf@sfritsch.de>
 .\"
@@ -14,7 +14,7 @@
 .\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 .\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 .\"
-.Dd $Mdocdate: May 9 2014 $
+.Dd $Mdocdate: June 17 2014 $
 .Dt VIO 4
 .Os
 .Sh NAME
@@ -29,10 +29,15 @@ driver provides support for the
 .Xr virtio 4
 network interface provided by bhyve, KVM, QEMU, and VirtualBox.
 .Pp
-Setting flags to 0x02 disables the RingEventIndex feature.
+Setting the bit 0x2 in the flags disables the RingEventIndex feature.
 This can be tried as a workaround for possible bugs in host implementations or
 .Nm
 at the cost of slightly reduced performance.
+.Pp
+Setting the bit 0x100 in the flags forces the interface to be always in
+promiscous mode.
+This can be used as a workaround for a bug in QEMU before version 2.0 that
+prevents packets with a VLAN tag to be sent to the guest.
 .Sh SEE ALSO
 .Xr intro 4 ,
 .Xr virtio 4
@@ -54,8 +59,3 @@ It is based on the
 .Nm vioif
 driver by
 .An Minoura Makoto .
-.Sh BUGS
-Due to a qemu bug, VLANs don't work with qemu versions before 2.0 unless the
-interface is in promiscuous mode.
-.Nm
-should probably implement a workaround for this.
diff --git a/sys/dev/pci/if_vio.c b/sys/dev/pci/if_vio.c
index cd6d419b834..3621489679b 100644
--- a/sys/dev/pci/if_vio.c
+++ b/sys/dev/pci/if_vio.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: if_vio.c,v 1.15 2014/01/19 20:49:02 bluhm Exp $	*/
+/*	$OpenBSD: if_vio.c,v 1.16 2014/06/17 19:46:13 sf Exp $	*/
 
 /*
  * Copyright (c) 2012 Stefan Fritsch, Alexander Fiveg.
@@ -91,6 +91,13 @@
 #define VIRTIO_NET_F_CTRL_RX_EXTRA	(1<<20)
 #define VIRTIO_NET_F_GUEST_ANNOUNCE	(1<<21)
 
+/*
+ * Config(8) flags. The lowest byte is reserved for generic virtio stuff.
+ */
+
+/* Workaround for vlan related bug in qemu < version 2.0 */
+#define CONFFLAG_QEMU_VLAN_BUG		(1<<8)
+
 static const struct virtio_feature_name virtio_net_feature_names[] = {
 	{ VIRTIO_NET_F_CSUM,		"CSum" },
 	{ VIRTIO_NET_F_GUEST_CSUM,	"GuestCSum" },
@@ -1395,6 +1402,9 @@ vio_iff(struct vio_softc *sc)
 		return;
 	}
 
+	if (sc->sc_dev.dv_cfdata->cf_flags & CONFFLAG_QEMU_VLAN_BUG)
+		ifp->if_flags |= IFF_PROMISC;
+
 	if (ifp->if_flags & IFF_PROMISC || ac->ac_multirangecnt > 0 ||
 	    ac->ac_multicnt >= VIRTIO_NET_CTRL_MAC_MC_ENTRIES) {
 		ifp->if_flags |= IFF_ALLMULTI;