Re: [Xen-devel] [PATCH] x86/svm: Drop support for AMD's Lightweight Profiling

["Woods, Brian" <Brian.Woods@xxxxxxx>]

On Mon, May 20, 2019 at 11:13:36AM +0100, Andy Cooper wrote:
> Lightweight Profiling was introduced in Bulldozer (Fam15h), but was dropped
> from Zen (Fam17h) processors.  Furthermore, LWP was dropped from Fam15/16 CPUs
> when IBPB for Spectre v2 was introduced in microcode, owing to LWP not being
> used in practice.
> 
> As a result, CPUs which are operating within specification (i.e. with up to
> date microcode) no longer have this feature, and therefore are not using it.
> 
> Drop support from Xen.  The main motivation here is to remove unnecessary
> complexity from CPUID handling, but it also tidies up the SVM code nicely.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Acked-by: Brian Woods <brian.woods@xxxxxxx>

I've confirmed with HW engineers that it's going away.

-- 
Brian Woods

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