> On Jun 28, 2015, at 18:34 PM, Brian Kress <bkr...@egenera.com> wrote: > > When running ESXi under qemu there is an issue with the ESXi guest > discarding packets that are too short. The guest discards any packets > under the normal minimum length for an ethernet packet (60). This > results in odd behaviour where other hosts or VMs on other hosts can > communicate with the ESXi guest just fine (since there's a physical NIC > somewhere doing padding), but VMs on the host and the host itself cannot > because the ARP request packets are too small for the ESXi host to > accept. > Someone in the past thought this was worth fixing, and added code to > the vmxnet3 qemu emulation such that if it is receiving packets smaller > than 60 bytes to pad the packet out to 60. Unfortunately this code is > wrong (or at least in the wrong place). It does so BEFORE before taking > into account the vnet_hdr at the front of the packet added by the tap > device. As a result, it might add padding, but it never adds enough. > Specifically it adds 10 less (the length of the vnet_hdr) than it > needs to. > The following (hopefully "obviously correct") patch simply swaps > the order of processing the vnet header and the padding. With this > patch an ESXi guest is able to communicate with the host or other local > VMs. > > Signed-off-by: Brian Kress <kre...@moose.net> > > --- a/hw/net/vmxnet3.c 2015-04-27 10:08:24.000000000 -0400 > +++ b/hw/net/vmxnet3.c 2015-06-23 11:38:48.865728713 -0400 > @@ -1879,6 +1879,12 @@ > return -1; > } > > + if (s->peer_has_vhdr) { > + vmxnet_rx_pkt_set_vhdr(s->rx_pkt, (struct virtio_net_hdr *)buf); > + buf += sizeof(struct virtio_net_hdr); > + size -= sizeof(struct virtio_net_hdr); > + } > + > /* Pad to minimum Ethernet frame length */ > if (size < sizeof(min_buf)) { > memcpy(min_buf, buf, size); > @@ -1887,12 +1893,6 @@ > size = sizeof(min_buf); > } > > - if (s->peer_has_vhdr) { > - vmxnet_rx_pkt_set_vhdr(s->rx_pkt, (struct virtio_net_hdr *)buf); > - buf += sizeof(struct virtio_net_hdr); > - size -= sizeof(struct virtio_net_hdr); > - } > -
Looks good. ~Dmitry. > vmxnet_rx_pkt_set_packet_type(s->rx_pkt, > get_eth_packet_type(PKT_GET_ETH_HDR(buf))); >