Re: [PATCH v2 1/4] x86/cpuid: Split dom0 handling out of init_domain_cpuid_policy()

[Andrew Cooper <amc96@xxxxxxxx>]

On 16/12/2021 16:38, Jan Beulich wrote:
> On 15.12.2021 23:21, Andrew Cooper wrote:
>> To implement dom0-cpuid= support, the special cases would need extending.
>> However there is already a problem with late hwdom where the special cases
>> override toolstack settings, which is unintended and poor behaviour.
>>
>> Introduce a new init_dom0_cpuid_policy() for the purpose, moving the ITSC and
>> ARCH_CAPS logic.  The is_hardware_domain() can be dropped, and for now there
>> is no need to rerun recalculate_cpuid_policy(); this is a relatively 
>> expensive
>> operation, and will become more-so over time.
> Would you mind leaving it there in a commented out form, hinting at when
> it may need re-enabling?

Leave what?  The recalculate_cpuid_policy()?  That comes back in later
in the series.

~Andrew

>
>> Rearrange the logic in create_dom0() to make room for a call to
>> init_dom0_cpuid_policy().  The AMX plans for having variable sized XSAVE
>> states require that modifications to the policy happen before vCPUs are
>> created.
>>
>> Additionally, factor out domid into a variable so we can be slightly more
>> correct in the case of a failure, and also print the error from
>> domain_create().  This will at least help distinguish -EINVAL from -ENOMEM.
>>
>> No practical change in behaviour.
>>
>> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> Preferably with said comment added:
> Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
>
> Jan
>
>