Re: [Xen-devel] [PATCH] tools/misc: Tweak reserved bit handling for xen-cpuid

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 27/02/18 16:38, Jan Beulich wrote:
>>>> On 27.02.18 at 17:28, <andrew.cooper3@xxxxxxxxxx> wrote:
>> Instead of printing REZ, use NULL pointers to indicate missing information,
>> and have dump_leaf() print out the bit which is unknown.
>>
>> E.g.
>>
>> ....
>> Dynamic sets:
>> Raw                       
>> 178bfbff:fed8320b:2fd3fbff:35c233ff:0000000f:209c01a9:00000000:00006799:00001007:00000000
>>   [00] 0x00000001.edx     fpu vme de pse tsc msr pae mce cx8 apic sysenter 
>> mtrr pge  ...
>>   [01] 0x00000001.ecx     sse3 pclmulqdq monitor ssse3 fma cx16 sse41 sse42 
>> movebe   ...
>>   [02] 0x80000001.edx     fpu vme de pse tsc msr pae mce cx8 apic syscall 
>> mtrr pge   ...
>>   [03] 0x80000001.ecx     lahf_lm cmp svm extapic cr8d lzcnt sse4a msse 
>> 3dnowpf osvw ...
>>   [04] 0x0000000d:1.eax   xsaveopt xsavec xgetbv1 xsaves
>>   [05] 0x00000007:0.ebx   fsgsbase bmi1 avx2 smep bmi2 rdseed adx smap 
>> clflushopt sha
>>   [06] 0x00000007:0.ecx
>>   [07] 0x80000007.edx     <BIT0> <BIT3> <BIT4> <BIT7> itsc <BIT9> efro 
>> <BIT13> <BIT14>
>>   [08] 0x80000008.ebx     clzero <BIT1> <BIT2> ibpb
>>   [09] 0x00000007:0.edx
> How about omitting the BIT part, making it just <0> etc, which still
> makes clear the bit is set but has no name? Other than that ...

Hmm

  [07] 0x80000007.edx     <0> <3> <4> <7> itsc <9> efro <13> <14>
  [08] 0x80000008.ebx     clzero <1> <2> ibpb

Yes - I think I prefer that.

>
>> which is the output on an AMD EPYC system, where Xen doesn't know about, and
>> has therefore masked, most of the more advanced thermal/perf features.
>>
>> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>

Thanks,

~Andrew

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