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Re: [Xen-devel] [PATCH 2/2] x86/HVM: adjust feature checking in MSR intercept handling



>>> On 07.09.16 at 07:36, <kevin.tian@xxxxxxxxx> wrote:
>>  From: Jan Beulich [mailto:JBeulich@xxxxxxxx]
>> Sent: Friday, September 02, 2016 6:22 PM
>> 
>> Consistently consult hvm_cpuid(). With that, BNDCFGS gets better
>> handled outside of VMX specific code, just like XSS. Don't needlessly
>> check for MTRR support when the MSR being accessed clearly is not an
>> MTRR one.
>> 
>> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
>> 
> 
> A nice cleanup. Just one comment:
> 
>> @@ -3824,9 +3850,8 @@ int hvm_msr_write_intercept(unsigned int
>>          break;
>> 
>>      case MSR_MTRRcap:
>> -        if ( !mtrr )
>> -            goto gp_fault;
>>          goto gp_fault;
>> +
> 
> what's point of removing above mtrr check?

Isn't that obvious: No matter what value "mtrr" has, we
"goto gp_fault".

Jan


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