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

[Andrew Cooper <Andrew.Cooper3@xxxxxxxxxx>]

On 26/01/2022 13:47, Andrew Cooper wrote:
> On 26/01/2022 13:37, Andrew Cooper wrote:
>> On 26/01/2022 12:44, Roger Pau Monné wrote:
>>> 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?
>> Hmm - I may have a mistake here.
>>
>> Boot time CPUID handling is giant mess, and I haven't had time to finish
>> my work to make BSP microcode loading dependent on xmalloc(), allowing
> Sorry.  I mean "independent" here.
>
> ~Andrew
>
>> it to move far earlier, and removing the early/late CPUID split.
>>
>> However, init_speculative_mitigations() is called after late CPUID
>> setup, so e8b should be suitably collected.  Let me try to figure out
>> what's going on.

And testing shows that everything works fine without this patch.  I must
have had some breakage during development which has resolved itself as
part of cleaning the series up.

Anyway, I'll withdraw this patch.

~Andrew