Re: [Xen-devel] [PATCH v3 04/24] x86: Don't use potentially incorrect CPUID values for topology information

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Tue, Jan 09, 2018 at 04:02:38PM -0800, Anthony Liguori wrote:
> From: Jan H. Schönherr <jschoenh@xxxxxxxxx>
> 
> Intel says for CPUID leaf 0Bh:
> 
>   "Software must not use EBX[15:0] to enumerate processor
>    topology of the system. This value in this field
>    (EBX[15:0]) is only intended for display/diagnostic
>    purposes. The actual number of logical processors
>    available to BIOS/OS/Applications may be different from
>    the value of EBX[15:0], depending on software and platform
>    hardware configurations."
> 
> And yet, we're using them to derive the number cores in a package
> and the number of siblings in a core.
> 
> Derive the number of siblings and cores from EAX instead, which is
> intended for that.
> 
> Signed-off-by: Jan H. Schönherr <jschoenh@xxxxxxxxx>

This is already merged to staging.

Wei.

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