Re: [PATCH 3/3] x86/amd: Delay amd_init_levelling() until after fixes to the CPUID MSRs

[Jan Beulich <jbeulich@xxxxxxxx>]

On 02.12.2025 11:57, Andrew Cooper wrote:
> There's no need for amd_init_levelling() to be specifically early.  In fact,
> it must be after init_amd() edits the feature MSRs, e.g. enabling TOPOEXT on
> Fam15h, or we revert the change on the next context switch.

However, ...

> @@ -1270,10 +1262,14 @@ static void cf_check init_amd(struct cpuinfo_x86 *c)
>       check_syscfg_dram_mod_en();
>  
>       amd_log_freq(c);
> +
> +     if (c == &boot_cpu_data)
> +             amd_init_levelling(); /* After CPUID MSR adjustments. */
> +
> +     ctxt_switch_levelling(NULL);
>  }

... this new placement conflicts with the two RDSEED patches which have been
pending for a while / too long. Even moving up wouldn't help, as the TOPOEXT
re-enabling is after the switch() that the RDSEED changes are being fit into.
Surely I could re-base accordingly, but it kind of feels that the older
changes should go in first, with whatever adjustments necessary done either
here, or (in a preparatory and agreed upon manner) right there, or entirely
independently.

Looks like it would be possible to move the TOPOEXT re-enabling ahead of that
very switch(), for the code above then to be inserted between that and said
switch().

Jan