Re: [Xen-devel] [PATCH v2 07/14] x86/cpuid: Handle leaves 0x80000005-7 in guest_cpuid()

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 24/01/17 15:05, Jan Beulich wrote:
>>>> On 24.01.17 at 15:48, <andrew.cooper3@xxxxxxxxxx> wrote:
>> On 24/01/17 11:59, Jan Beulich wrote:
>>>>>> On 23.01.17 at 15:39, <andrew.cooper3@xxxxxxxxxx> wrote:
>>>> Intel reserves all of this information other than the L2 cache information,
>>>> and the ITSC bit from the power management leaf.
>>>>
>>>> AMD passes all of the cache/TLB information through to the guest, while 
>>>> most
>>>> of of the power management information is explicitly clobbered by the
>>>> toolstack.
>>> Both of these look to not be fully in line with ...
>>>
>>>> --- a/xen/arch/x86/cpuid.c
>>>> +++ b/xen/arch/x86/cpuid.c
>>>> @@ -167,6 +167,9 @@ static void recalculate_misc(struct cpuid_policy *p)
>>>>  
>>>>      p->extd.e1d &= ~CPUID_COMMON_1D_FEATURES;
>>>>  
>>>> +    /* Most of Power/RAS hidden from guests. */
>>>> +    p->extd.raw[0x7].a = p->extd.raw[0x7].b = p->extd.raw[0x7].c = 0;
>>> ... you leaving .d completely untouched. Can you clarify this please?
>> e7d is covered by the featureset bitmap, because it contains the ITSC
>> feature.
>>
>> It is therefore covered by the main body of recalculate_domain_policy().
> Oh, of course.
>
> Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>

Thanks.  I will tweak the commit message to make this clearer.

~Andrew

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