Re: [PATCH V6 2/5] perf/x86/kvm: Avoid unnecessary work in guest filtering

Liang, Kan
2019-02-04T15:57:38Z

On 2/4/2019 10:44 AM, Peter Zijlstra wrote:
> On Mon, Feb 04, 2019 at 04:38:27PM +0100, Peter Zijlstra wrote:
>> +static const struct x86_cpu_desc isolation_ucodes[] = {
>> + INTEL_CPU_DESC(INTEL_FAM6_KABYLAKE_MOBILE, 9, 0x0000004e),
>> + INTEL_CPU_DESC(INTEL_FAM6_KABYLAKE_MOBILE, 10, 0x0000004e),
>> + INTEL_CPU_DESC(INTEL_FAM6_KABYLAKE_MOBILE, 11, 0x0000004e),
>> + INTEL_CPU_DESC(INTEL_FAM6_KABYLAKE_MOBILE, 12, 0x0000004e),
>
>> + INTEL_CPU_DESC(INTEL_FAM6_KABYLAKE_DESKTOP, 10, 0x0000004e),
>> + INTEL_CPU_DESC(INTEL_FAM6_KABYLAKE_DESKTOP, 11, 0x0000004e),
>> + INTEL_CPU_DESC(INTEL_FAM6_KABYLAKE_DESKTOP, 12, 0x0000004e),
>> + INTEL_CPU_DESC(INTEL_FAM6_KABYLAKE_DESKTOP, 13, 0x0000004e),
>
> Do we want a special stepping (0 / -1) to be able to denote 'all' ?
>

Something like as below?
#define X86_STEPPING_ANY 0xff

As my understanding, the microcode version for each stepping is
independent and irrelevant. The 0x0000004e should be just coincidence.
If so, I don't think X86_STEPPING_ANY is very useful.

Andi, if I'm wrong please correct me.

Thanks,
Kan