Re: [Xen-devel] [PATCH 18/27] x86/pv: Use per-domain policy information in pv_cpuid()

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 05/01/17 12:44, Jan Beulich wrote:
>>>> On 04.01.17 at 13:39, <andrew.cooper3@xxxxxxxxxx> wrote:
>> --- a/xen/arch/x86/traps.c
>> +++ b/xen/arch/x86/traps.c
>> @@ -1065,11 +1065,8 @@ void pv_cpuid(struct cpu_user_regs *regs)
>>          uint32_t tmp;
>>  
>>      case 0x00000001:
>> -        c &= pv_featureset[FEATURESET_1c];
>> -        d &= pv_featureset[FEATURESET_1d];
>> -
>> -        if ( is_pv_32bit_domain(currd) )
>> -            c &= ~cpufeat_mask(X86_FEATURE_CX16);
>> +        c = p->basic._1c;
>> +        d = p->basic._1d;
> Being able to drop the clearing of CX16 is because it depends on
> LM, and LM gets cleared explicitly in recalculate_cpuid_policy(). If
> that's right (and intended that way),
> Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>

Yes.  I will update the commit message to explicitly state that
recalculate_cpuid_policy() performs these adjustments when the policy is
loaded.

~Andrew

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