On 10/29/2018 3:11 PM, John Fastabend wrote:

On 10/29/2018 02:19 PM, Shannon Nelson wrote:

quoted

This is an example of using XDP to redirect the processing of
particular vlan packets to specific CPUs.  This is in response
to comments received on a kernel patch put forth previously
to do something similar using RPS.
      https://www.spinics.net/lists/netdev/msg528210.html
      [PATCH net-next] net: enable RPS on vlan devices

This XDP application watches for inbound vlan-tagged packets
and redirects those packets to be processed on a specific CPU
as configured in a BPF map.  The BPF map can be modified by
this user program, which can also load and unload the kernel
XDP code.

One example use is for supporting VMs where we can't control the
OS being used: we'd like to separate the VM CPU processing from
the host's CPUs as a way to help mitigate L1TF related issues.
When running the VM's traffic on a vlan we can stick the host's
Rx processing on one set of CPUs separate from the VM's CPUs.

This example currently uses a vlan key and cpu value in the
BPF map, so only can do one CPU per vlan.  This could easily
be modified to use a bitpattern of CPUs rather than a CPU id
to allow multiple CPUs per vlan.

Great, so does this solve your use case then? At least on drivers
with XDP support?

Well, more or less... the actual issue was a request for our UEK5 
distribution, based on v4.14, which doesn't have support for the CPU 
redirect.  Internal discussion continues.

quoted

Signed-off-by: Shannon Nelson <redacted>
---

Some really small and trivial nits below.

Acked-by: John Fastabend <john.fastabend@gmail.com>

Thanks,
sln