Re: [PATCH] x86/CPU/AMD: Fix LLC ID bit-shift calculation

Suthikulpanit, Suravee
2018-06-18T18:14:25Z

Boris,

On 6/18/2018 12:20 PM, Borislav Petkov wrote:
> On Wed, Jun 13, 2018 at 01:43:10PM -0500, Suravee Suthikulpanit wrote:
>> The current logic incorrectly calculates the LLC ID from the APIC ID.
>> Unless specified otherwise, the LLC ID should be calculated from
>> the count order of the number of threads sharing cache.
>
> Don't you mean:
>
> "... should be calculated by removing the Core and Thread ID bits"?
>
> here?
>
> I'm looking at
>
> "2.1.10.2.1.3 ApicId Enumeration Requirements
>
> ...
>
> Each Core::X86::Apic::ApicId[ApicId] register is preset as follows:
> • ApicId[6] = Socket ID.
> • ApicId[5:4] = Node ID.
> • ApicId[3] = Logical CCX L3 complex ID
> • ApicId[2:0]= (SMT) ? {LogicalCoreID[1:0],ThreadId} : {1'b0,LogicalCoreID[1:0]}.
>
> and in order to get a unique LLC ID, you simply need to shift out the
> CoreID and the ThreadId, right?
>
> Or am I misreading it?
>

This enumeration is only for the family17h model 00-1Fh of hardware
revision. The patch is intended for the future revision of hardware.

Thanks,
Suravee