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rocker: mark copy-to-cpu pkts as forwarding offloaded

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For pkts copied to the CPU (to be processed by guest driver), mark the Rx
descriptor with flag "OFFLOAD_FWD" to indicate device has already forwarded
pkt.  The guest driver will use this indicator to avoid duplicate
forwarding in the guest OS.

Examples include bcast/mcast/unknown ucast pkts flooded to bridged ports.
We want to avoid both the device and the guest bridge driver flooding these
pkts, which would result in duplicates pkts on the wire.  Packet sampling,
such as sFlow, can also use this technique to mark pkts for the guest OS to
record but otherwise drop.

Signed-off-by: Scott Feldman <sfeldma@gmail.com>
Message-id: 1435746792-41278-5-git-send-email-sfeldma@gmail.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Scott Feldman 2015-07-01 03:33:11 -07:00 • committed by Stefan Hajnoczi
parent 96497af0af
commit d0d2555852
5 changed files with 15 additions and 3 deletions
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4
docs/specs/rocker.txt
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@ -637,6 +637,7 @@ The TLVs for Rx descriptor buffer are:
(1 << 5): TCP packet
(1 << 6): UDP packet
(1 << 7): TCP/UDP csum good
(1 << 8): Offload forward
RX_CSUM 2 IP calculated checksum:
IPv4: IP payload csum
IPv6: header and payload csum
@ -645,6 +646,9 @@ The TLVs for Rx descriptor buffer are:
RX_FRAG_MAX_LEN 2 Packet maximum fragment length
RX_FRAG_LEN 2 Actual packet fragment length after receive
Offload forward RX_FLAG indicates the device has already forwarded the packet
so the host CPU should not also forward the packet.
Possible status return codes in descriptor on completion are:
DESC_COMP_ERR reason