Re: [PATCH 3/7] x86/boot: Collect the Raw CPU Policy earlier on boot

[Jan Beulich <jbeulich@xxxxxxxx>]

On 23.05.2024 13:16, Andrew Cooper wrote:
> This is a tangle, but it's a small step in the right direction.
> 
> xstate_init() is shortly going to want data from the Raw policy.
> calculate_raw_cpu_policy() is sufficiently separate from the other policies to
> be safe to do.
> 
> No functional change.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

Would you mind taking a look at
https://lists.xen.org/archives/html/xen-devel/2021-04/msg01335.html
to make clear (to me at least) in how far we can perhaps find common grounds
on what wants doing when? (Of course the local version I have has been
constantly re-based, so some of the function names would have changed from
what's visible there.)

> --- a/xen/arch/x86/cpu-policy.c
> +++ b/xen/arch/x86/cpu-policy.c
> @@ -845,7 +845,6 @@ static void __init calculate_hvm_def_policy(void)
>  
>  void __init init_guest_cpu_policies(void)
>  {
> -    calculate_raw_cpu_policy();
>      calculate_host_policy();
>  
>      if ( IS_ENABLED(CONFIG_PV) )
> --- a/xen/arch/x86/setup.c
> +++ b/xen/arch/x86/setup.c
> @@ -1888,7 +1888,9 @@ void asmlinkage __init noreturn __start_xen(unsigned 
> long mbi_p)
>  
>      tsx_init(); /* Needs microcode.  May change HLE/RTM feature bits. */
>  
> -    identify_cpu(&boot_cpu_data);
> +    calculate_raw_cpu_policy(); /* Needs microcode.  No other dependenices. 
> */
> +
> +    identify_cpu(&boot_cpu_data); /* Needs microcode and raw policy. */

You don't introduce any dependency on raw policy here, and there cannot possibly
have been such a dependency before (unless there was a bug somewhere). Therefore
I consider this latter comment misleading at this point.

Jan