Re: [Xen-devel] [PATCH] libx86/CPUID: fix (not just) leaf 7 processing

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 23/03/2020 12:06, Jan Beulich wrote:
> For one, subleaves within the respective union shouldn't live in
> separate sub-structures.

Oops, and of course this stays hidden right now because there is no
overlap in known bits between subleaf 0 and 1 yet.

> And then x86_cpuid_policy_fill_native() should,
> as it did originally, iterate over all subleaves here as well as over
> all main leaves.

I was clearly asleep when writing that bugfix.  Again - it says hidden
because our local max_leaves are lower than ~all hardware these days.

>  Switch to using a "<= MIN()"-based approach similar to
> that used in x86_cpuid_copy_to_buffer(). Also follow this for the
> extended main leaves then.
>
> Fixes: 1bd2b750537b ("libx86: Fix 32bit stubdom build of 
> x86_cpuid_policy_fill_native()")
> Fixes: 97e4ebdcd765 ("x86/CPUID: support leaf 7 subleaf 1 / AVX512_BF16")
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>