svn commit: r361944 - in head/sys/dev/virtio: . network

[Vincenzo Maffione]

You may already know that, but FreeBSD-CURRENT supports mergeable rx
buffers as of r358180.

Cheers,
  Vincenzo

Il giorno dom 14 giu 2020 alle ore 22:56 Jessica Clarke <jrtc27 at freebsd.org>
ha scritto:

> On 14 Jun 2020, at 20:51, Tom Jones <thj at freebsd.org> wrote:
> > On Mon, Jun 08, 2020 at 09:51:36PM +0000, Jessica Clarke wrote:
> >> Author: jrtc27
> >> Date: Mon Jun  8 21:51:36 2020
> >> New Revision: 361944
> >> URL: https://svnweb.freebsd.org/changeset/base/361944
> >>
> >> Log:
> >>  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
> >>
> >> Modified:
> >>  head/sys/dev/virtio/network/if_vtnet.c
> >>  head/sys/dev/virtio/network/if_vtnetvar.h
> >>  head/sys/dev/virtio/virtio.c
> >>  head/sys/dev/virtio/virtqueue.c
> >>
> >
> > Hi Jessica,
> >
> > After updating my current bhyve vm today (on a 12.1 host), networking no
> longer
> > works. Reverting this commit seems to resolve the issue. I think vtnet
> is not
> > passing enough data up to the ip layer.
> >
> > If I capture on the tap interface for the vm I see arp requests and arp
> > replies, however kern.msgbuf is full of:
> >
> > <5>arp: short packet received on vtnet0
> >
> > and netstat does not see any replies to arp requests:
> >
> > root at freebsd-current:~ # netstat -s -p arp
> > arp:
> >        11 ARP requests sent
> >        0 ARP requests failed to sent
> >        0 ARP replies sent
> >        0 ARP requests received
> >        0 ARP replies received
> >        0 ARP packets received
> >        24 total packets dropped due to no ARP entry
> >        2 ARP entrys timed out
> >        0 Duplicate IPs seen
> >
> > If I set up an arp entry manually I can see ICMP echo requests and
> responses on
> > the tap interface, but the vm does not see the responses.
> >
> > root at freebsd-current:~ # netstat -s -p ip
> > ip:
> >        7 total packets received
> >        0 bad header checksums
> >        0 with size smaller than minimum
> >        7 with data size < data length
> >        0 with ip length > max ip packet size
> >        0 with header length < data size
> >        0 with data length < header length
> >
> > The line
> >
> >        7 with data size < data length
> >
> > makes me think that vtnet is truncating packets.
> >
> > markj pointed me at this bug in irc which might also be related:
> >
> > https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=247242
>
> Hi Tom,
> Sorry about that; it seems bhyve hits the "legacy and no MrgRxBuf"
> case. Could you please try the patch below?
>
> Jess
>
> diff --git a/sys/dev/virtio/network/if_vtnet.c
> b/sys/dev/virtio/network/if_vtnet.c
> index 7a0859cc0eb1..7e10b75f7f66 100644
> --- a/sys/dev/virtio/network/if_vtnet.c
> +++ b/sys/dev/virtio/network/if_vtnet.c
> @@ -1819,9 +1819,10 @@ vtnet_rxq_eof(struct vtnet_rxq *rxq)
>              adjsz = sizeof(struct vtnet_rx_header);
>              /*
>               * Account for our pad inserted between the header
> -             * and the actual start of the frame.
> +             * and the actual start of the frame. This includes
> +             * the unused num_buffers when using a legacy device.
>               */
> -            len += VTNET_RX_HEADER_PAD;
> +            len += adjsz - sc->vtnet_hdr_size;
>          } else {
>              mhdr = mtod(m, struct virtio_net_hdr_mrg_rxbuf *);
>              nbufs = mhdr->num_buffers;
>
>