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Re: [PATCH 2/8] x86/boot: Collect AMD speculative features earlier during boot


  • To: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
  • From: Roger Pau Monné <roger.pau@xxxxxxxxxx>
  • Date: Wed, 26 Jan 2022 13:44:31 +0100
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  • Cc: Xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxxx>, Jan Beulich <JBeulich@xxxxxxxx>, Wei Liu <wl@xxxxxxx>
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On Wed, Jan 26, 2022 at 08:44:46AM +0000, Andrew Cooper wrote:
> All AMD IBRS-related features are in CPUID.0x80000008.ebx.  Collect them in
> early_cpu_init() so init_speculative_mitigations() can use them.
> 
> Rework the existing logic structure to fill in c->extended_cpuid_level and
> separate out the ambiguous use of ebx in an otherwise 0x80000008-specific
> logic block.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

Reviewed-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>

It would be good to update the comment ahead of early_cpu_init to
mention it now also gather speculation-related fields from CPUID in
order to do early setup of mitigations.

I think you could also use boot_cpu_data in spec_ctrl.c print_details
instead of fetching again the cpuid leafs?

Thanks, Roger.



 


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