Re: [Xen-devel] [PATCH v5 03/14] x86emul: abstract out XCRn accesses

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 15.03.18 at 14:35, <andrew.cooper3@xxxxxxxxxx> wrote:
> On 15/03/18 13:04, Jan Beulich wrote:
>>  static inline void x86_emul_hw_exception(
>> --- a/xen/arch/x86/x86_emulate.c
>> +++ b/xen/arch/x86/x86_emulate.c
>> @@ -42,3 +42,50 @@
>>  })
>>  
>>  #include "x86_emulate/x86_emulate.c"
>> +
>> +int x86emul_read_xcr(unsigned int reg, uint64_t *val,
>> +                     struct x86_emulate_ctxt *ctxt)
>> +{
>> +    switch ( reg )
>> +    {
>> +    case 0:
>> +        *val = current->arch.xcr0;
>> +        return X86EMUL_OKAY;
>> +
>> +    case 1:
>> +        if ( cpu_has_xgetbv1 && current->domain->arch.cpuid->xstate.xgetbv1 
>> )
> 
> You can drop the cpu_has_xgetbv1 part of this test.  The CPUID policy
> derivation logic won't allow xstate.xgetbv1 to be set without
> cpu_has_xgetbv1

Hmm, I wasn't sure: Is that already the case? I thought
auditing of what the tool stack provides is only planned.

> Otherwise, Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

Thanks, but please clarify the above.

Jan


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