Re: [PATCH v6 17/44] x86/boot: convert microcode loading to consume struct boot_info

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 17/10/2024 6:02 pm, Daniel P. Smith wrote:
> diff --git a/xen/arch/x86/cpu/microcode/core.c 
> b/xen/arch/x86/cpu/microcode/core.c
> index 8564e4d2c94c..22fea80bc97e 100644
> --- a/xen/arch/x86/cpu/microcode/core.c
> +++ b/xen/arch/x86/cpu/microcode/core.c
> @@ -178,16 +177,16 @@ static void __init microcode_scan_module(
>      /*
>       * Try all modules and see whichever could be the microcode blob.
>       */
> -    for ( i = 1 /* Ignore dom0 kernel */; i < mbi->mods_count; i++ )
> +    for ( i = 1 /* Ignore dom0 kernel */; i < bi->nr_modules; i++ )
>      {
>          if ( !test_bit(i, module_map) )
>              continue;
>  

Somewhere in this series, it would be nice to purge the these "module 0
is dom0" special cases.  I'm not sure where best in the series to do it,
and it may not be here.

Later, in "x86/boot: remove module_map usage from microcode loading" you
convert this test_bit() into a type != UNKNOWN check, but the pattern is
used elsewhere too.

How about a for_each_unknown_module(bi, bm) helper?  (which at this
point can even use module_map in scope).

If you introduce it at this point, then I think the churn later in the
series reduces marginally, and I think it removes all the "careful not
to look at dom0" special cases.

~Andrew