[PATCH v4 4/7] net/tap: rewrite the RSS BPF program

[Ferruh Yigit]

On 2/10/2024 2:09 AM, Stephen Hemminger wrote:
> On Sat, 10 Feb 2024 00:54:15 +0000
> Ferruh Yigit <ferruh.yigit at amd.com> wrote:
> 
>> On 2/8/2024 7:05 PM, Stephen Hemminger wrote:
>>> Rewrite the BPF program used to do queue based RSS.
>>> Important changes:
>>> 	- uses newer BPF map format BTF
>>> 	- accepts key as parameter rather than constant default
>>> 	- can do L3 or L4 hashing
>>> 	- supports IPv4 options
>>> 	- supports IPv6 extension headers
>>> 	- restructured for readability
>>>
>>> The usage of BPF is different as well:
>>> 	- the incoming configuration is looked up based on
>>> 	  class parameters rather than patching the BPF.
>>> 	- the resulting queue is placed in skb rather
>>> 	  than requiring a second pass through classifier step.
>>>
>>> Note: This version only works with later patch to enable it on
>>> the DPDK driver side. It is submitted as an incremental patch
>>> to allow for easier review. Bisection still works because
>>> the old instruction are still present for now.
>>>
>>> Signed-off-by: Stephen Hemminger <stephen at networkplumber.org>  
>>
>> <...>
>>
>>> diff --git a/drivers/net/tap/bpf/meson.build b/drivers/net/tap/bpf/meson.build
>>> new file mode 100644
>>> index 000000000000..f2c03a19fd4d
>>> --- /dev/null
>>> +++ b/drivers/net/tap/bpf/meson.build
>>> @@ -0,0 +1,81 @@
>>> +# SPDX-License-Identifier: BSD-3-Clause
>>> +# Copyright 2024 Stephen Hemminger <stephen at networkplumber.org>
>>> +
>>> +enable_tap_rss = false
>>> +
>>> +libbpf = dependency('libbpf', required: false, method: 'pkg-config')
>>> +if not libbpf.found()
>>> +    message('net/tap: no RSS support missing libbpf')
>>> +    subdir_done()
>>> +endif
>>> +
>>> +# Debian install this in /usr/sbin which is not in $PATH
>>> +bpftool = find_program('bpftool', '/usr/sbin/bpftool', required: false, version: '>= 5.6.0')
>>> +if not bpftool.found()
>>> +    message('net/tap: no RSS support missing bpftool')
>>> +    subdir_done()
>>> +endif
>>>  
>>
>> I am getting following build error:
>> '
>> drivers/net/tap/bpf/meson.build:13:10: ERROR: Command `/usr/sbin/bpftool
>> --version` failed with status 2.
>> '
>>
>> There is a '/usr/sbin/bpftool' file but it is a script and gives
>> following message when run:
>> "WARNING: bpftool not found for kernel 6.5.0-15"
>>
>> This is with "Ubuntu 22.04.3 LTS"
>>
>>
>> Overall thanks for fixing tap BPF support.
> 
> Just set up an equivalent Ubuntu VM 22.04 VM and made sure all packages
> were up to date.
> 
> Looks like Ubuntu borked the packaging of bpftool.
> Maybe Luca has some insight.
> 
> shemminger at ubuntu-22-04:~/dpdk$ sudo apt install libbpf-dev bpftool
> Reading package lists... Done
> Building dependency tree... Done
> Reading state information... Done
> Package bpftool is a virtual package provided by:
>   linux-nvidia-6.2-tools-common 6.2.0-1003.3~22.04.1
>   linux-lowlatency-hwe-6.5-tools-common 6.5.0-17.17.1.1.1~22.04.1
>   linux-hwe-6.5-tools-common 6.5.0-17.17~22.04.1
>   linux-hwe-6.2-tools-common 6.2.0-39.40~22.04.1
> You should explicitly select one to install.
> 

I can make it work but it can hit others too, we need something that
detects this condition and disables tap/bpf.