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

[Andrew Cooper <amc96@xxxxxxxx>]

On 16/12/2021 16:51, Jan Beulich wrote:
> On 16.12.2021 17:41, Andrew Cooper wrote:
>> 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.
> I've meanwhile spotted it, yes. Let's hope its conditional invocation
> there makes clear enough that with certain other changes it may also
> be needed.

In reality, I expect ITSC never to need a recalc, and ARCH_CAPS is going
to turn into not-a-special-case just as soon as I can possibly make it
happen.

~Andrew