system-tso: Skip encap tests when userspace TSO is enabled.

It seems Linux native tunnel configuration changed to enable
checksum by default and that causes the check-system-tso unit
test below to fail:
 10: datapath - ping over vxlan tunnel    FAILED (system-traffic.at:248)

That happens because userspace TSO doesn't support encapsulation
as mentioned in the current documentation. In this specific case,
udp_extract_tnl_md() checks if the checksum is correct, but since
TSO is enabled, the outer UDP header contains only the pseudo
checksum and not the full packet checksum.

Although the packet is marked correctly with UDP csum offload flag
and the code could use that to verify the pseudo csum, more work
is needed to properly translate the offloading flags from the outer
headers to the inner headers.  For example, if the payload is a
TCP packet, most probably the flag DP_PACKET_OL_TX_UDP_CKSUM doesn't
make sense after decapsulating that.

This patch skips the tunnel tests when the userspace TSO is enabled.

Fixes: 29bb3093eb8b ("userspace: Enable TSO support for non-DPDK.")
Signed-off-by: Flavio Leitner <fbl@redhat.com>
Reviewed-by: David Marchand <david.marchand@redhat.com>
Signed-off-by: Ilya Maximets <i.maximets@ovn.org>

0 files changed, 0 insertions, 0 deletions