Re: [Xen-devel] [PATCH v2] x86: improve MSR_SHADOW_GS accesses

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 08/03/18 11:15, Jan Beulich wrote:
> Instead of using RDMSR/WRMSR, on fsgsbase-capable systems use a double
> SWAPGS combined with RDGSBASE/WRGSBASE. This halves execution time for
> a shadow GS update alone on my Haswell (and we have indications of
> good performance improvements by this on Skylake too), while the win is
> even higher when e.g. updating more than one base (as may and commonly
> will happen in load_segments()).
>
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

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