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docs: Add tunnel support to TSO GRE documentation.
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Previously support for tunnels was added to userspace TSO. However, the
documentation was not updated appropriately. This patch adds VxLAN and
Geneve as supported tunnels.

Fixes: 084c808 ("userspace: Support VXLAN and GENEVE TSO.")
Acked-by: David Marchand <[email protected]>
Signed-off-by: Mike Pattrick <[email protected]>
Signed-off-by: Ilya Maximets <[email protected]>
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mkp-rh authored and igsilya committed Jan 16, 2025
1 parent 6c77226 commit 6022b55
Showing 1 changed file with 9 additions and 8 deletions.
17 changes: 9 additions & 8 deletions Documentation/topics/userspace-tso.rst
Original file line number Diff line number Diff line change
Expand Up @@ -109,9 +109,9 @@ then started again. OvS will then report::
Limitations
~~~~~~~~~~~

The current OvS userspace `TSO` implementation supports flat and VLAN networks
only (i.e. no support for `TSO` over tunneled connection [VxLAN, GRE, IPinIP,
etc.]).
The current OvS userspace `TSO` implementation supports flat, VLAN networks,
and some tunneled connections. Currently only VxLAN and Geneve tunnels are
supported.

The NIC driver must support and advertise checksum offload for TCP and UDP.
However, SCTP is not mandatory because very few drivers advertised support
Expand All @@ -120,11 +120,12 @@ in Open vSwitch. Currently, if the NIC supports that, then the feature is
enabled, otherwise TSO can still be enabled but SCTP packets sent to the NIC
will be dropped.

There is no software implementation of TSO, so all ports attached to the
datapath must support TSO or packets using that feature will be dropped
on ports without TSO support. That also means guests using vhost-user
in client mode will receive TSO packet regardless of TSO being enabled
or disabled within the guest.
There is no software implementation of TSO in conjunction with tunnels. So
when VxLAN or Geneve tunnels are in use, all ports attached to the datapath
must support TSO or packets using this combination of features will be dropped
on ports without hardware TSO support. That also means guests using
vhost-user in client mode will receive TSO packet regardless of TSO being
enabled or disabled within the guest.

All kernel devices that use the raw socket interface (veth, for example)
require the kernel commit 9d2f67e43b73 ("net/packet: fix packet drop as of
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