On Fri, Jun 24, 2022 at 9:30 AM David Marchand
<[email protected]> wrote:
>
> As described in the bugzilla below, cpu_has_isa code may be compiled
> with some AVX512 instructions in it, because cpu.c is built as part of
> the libopenvswitchavx512.
> This is a problem when this function (supposed to probe for AVX512
> instructions availability) is invoked from generic OVS code, on older
> CPUs that don't support them.
>
> For the same reason, dpcls_subtable_avx512_gather_probe,
> dp_netdev_input_outer_avx512_probe, mfex_avx512_probe and
> mfex_avx512_vbmi_probe are potential runtime bombs and can't either be
> built as part of libopenvswitchavx512.
>
> Move cpu.c to be part of the "normal" libopenvswitch.
> And move other helpers in generic OVS code.
>
> Note:
> - dpcls_subtable_avx512_gather_probe is split in two, because it also
>   needs to do its own magic,
> - while moving those helpers, prefer direct calls to cpu_has_isa and
>   avoid cast to intermediate integer variables when a simple boolean
>   is enough,
>
> Fixes: b366fa2f4947 ("dpif-netdev: Call cpuid for x86 isa availability.")

Thinking again, there is probably more Fixes: lines to add.
I'll update for v2 if this current patch passes the CI.


-- 
David Marchand

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