From: Owen Smith Date: Tue, 5 Mar 2024 15:33:30 +0000 (+0000) Subject: Adjust Packet's MDL when stripping ETHERNET_TAG from headers X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=b5491f62d064a80cf3e2f1d69da53173a1b03b3b;p=pvdrivers%2Fwin%2Fxenvif.git Adjust Packet's MDL when stripping ETHERNET_TAG from headers Tagged headers have the ETHERNET_TAG stripped to convert to ETHERNET_UNTAGGED_HEADERs. As part of the fix up, the offsets for each header was adjusted, and the underlying MDL's MappedSystemVa was adjusted. However, the ByteCount and ByteOffset were not adjusted, resulting in instances of data corruption when MappedSystemVa != StartVa + ByteOffset. It is possible to configure the default gateway to respond to ARP packets with TPID wrappings. Openvswitch will not strip this header since this commit: commit f0fb825a3785320430686834741c718ff4f8ebf4 Author: Eric Garver Date: Wed Mar 1 17:47:59 2017 -0500 Add support for 802.1ad (QinQ tunneling) Which means Windows was receiving corrupted ARP responses, leading to an inability to access the network correctly. This would usually show as Windows indicating that no internet access was available, or being unable it access other VMs or other resources beyond the default gateway. Signed-off-by: Owen Smith --- diff --git a/src/xenvif/receiver.c b/src/xenvif/receiver.c index 0ce5b67..37e2c60 100644 --- a/src/xenvif/receiver.c +++ b/src/xenvif/receiver.c @@ -442,10 +442,11 @@ ReceiverRingProcessTag( Offset); // Fix up the packet information - BaseVa += sizeof (ETHERNET_TAG); + Packet->Mdl.MappedSystemVa = (PUCHAR)Packet->Mdl.MappedSystemVa + sizeof(ETHERNET_TAG); + Packet->Mdl.ByteOffset += sizeof(ETHERNET_TAG); + Packet->Mdl.ByteCount -= sizeof(ETHERNET_TAG); - BaseVa -= Packet->Offset; - Packet->Mdl.MappedSystemVa = BaseVa; + ASSERT3P((PUCHAR)Packet->Mdl.StartVa + Packet->Mdl.ByteOffset, ==, Packet->Mdl.MappedSystemVa); Packet->Length -= sizeof (ETHERNET_TAG);