Re: [Xen-devel] [PATCH 4/6] x86/hvm: Move hvm_funcs.cpuid_intercept() handling into hvm_cpuid()

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 16/11/16 16:40, Boris Ostrovsky wrote:
> On 11/16/2016 07:31 AM, Andrew Cooper wrote:
>> @@ -3700,6 +3701,14 @@ void hvm_cpuid(unsigned int input, unsigned int *eax, 
>> unsigned int *ebx,
>>  
>>          *ebx &= hvm_featureset[FEATURESET_e8b];
>>          break;
>> +
>> +    case 0x8000001c:
>> +        if ( !(v->arch.xcr0 & XSTATE_LWP) )
>> +            *eax = 0;
>> +        else if ( cpu_has_svm && cpu_has_lwp )
>> +            /* Turn on available bit and other features specified in 
>> lwp_cfg. */
>> +            *eax = (*edx & v->arch.hvm_svm.guest_lwp_cfg) | 1;
>> +        break;
>>      }
> You don't think this whole case should be under cpu_has_svm (or
> X86_VENDOR_AMD)?

LWP, being independently identifiable state should be gated on that
alone, even if in reality, it only exists on AMD hardware.

The use of cpu_has_svm is only because guest_lwp_cfg is in an svm
union.  Were guest_lwp_cfg to move, the condition should be relaxed.

~Andrew

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