Re: [Xen-devel] [PATCH v2 1/4] x86/vpmu: Move vpmu_do_cpuid() handling into {pv, hvm}_cpuid()

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 05/12/16 20:59, Boris Ostrovsky wrote:
> On 12/05/2016 01:24 PM, Andrew Cooper wrote:
>> @@ -3516,6 +3516,17 @@ void hvm_cpuid(unsigned int input, unsigned int *eax, 
>> unsigned int *ebx,
>>              if ( !(hvm_pae_enabled(v) || hvm_long_mode_enabled(v)) )
>>                  *edx &= ~cpufeat_mask(X86_FEATURE_PSE36);
>>          }
>> +
>> +        if ( vpmu_enabled(v) &&
>> +             vpmu_is_set(vcpu_vpmu(v), VPMU_CPU_HAS_DS) )
>> +        {
>> +            *edx |= cpufeat_mask(X86_FEATURE_DS);
>> +            if ( cpu_has(&current_cpu_data, X86_FEATURE_DTES64) )
>> +                *ecx |= cpufeat_mask(X86_FEATURE_DTES64);
>> +            if ( cpu_has(&current_cpu_data, X86_FEATURE_DSCPL) )
>> +                *ecx |= cpufeat_mask(X86_FEATURE_DSCPL);
>> +        }
>> +
>>          break;
>>  
>>      case 0x7:
>> @@ -3646,6 +3657,18 @@ void hvm_cpuid(unsigned int input, unsigned int *eax, 
>> unsigned int *ebx,
>>          }
>>          break;
>>  
>> +    case 0x0000000a: /* Architectural Performance Monitor Features (Intel) 
>> */
>> +        if ( boot_cpu_data.x86_vendor != X86_VENDOR_INTEL || 
>> !vpmu_enabled(v) )
>> +        {
>> +            *eax = *ebx = *ecx = *edx = 0;
>> +            break;
>> +        }
>> +
>> +        /* Report at most version 3 since that's all we currently emulate */
>> +        if ( (*eax & 0xff) > 3 )
>> +            *eax = (*eax & ~0xff) | 3;
>> +        break;
>
> Both this and Debug Store checks are the same for both HVM and PV. Can
> they be factored out?

The purpose of this patch series is to untangle the current call tree to
make it easier to finally merge the PV and HVM paths into a single
guest_cpuid().

Yes, this does add a bit of duplication in the short timer, but allows
for easier movement to the longterm goal.

> (and then perhaps version update can gain back PMU_VERSION_MASK macro)

That involves moving a whole load of Intel internals with generic names
into vpmu.h, which is why I chose not to do it.  The end result in
guest_cpuid() won't use it.

~Andrew

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