Greg KH wrote:
> -stable review patch.  If anyone has any objections, please let us know.
> 
> ------------------
> From: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
> 
> Note: This ACPI standard compliance may cause regression
> on some system, if they have _CST present, but _CST value
> is bogus. "nocst" module parameter should workaround
> that regression.
> 
> http://bugzilla.kernel.org/show_bug.cgi?id=5165
> 
> (cherry picked from 883baf7f7e81cca26f4683ae0d25ba48f094cc08 commit)
> 
> Signed-off-by: Venkatesh Pallipadi<venkatesh.pallipadi@intel.com>
> Signed-off-by: Len Brown <len.brown@intel.com>
> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
> ---
>  drivers/acpi/processor_idle.c |   10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)

Venkatesh followed up in a private email that a 3rd patch is needed to  solve 
the hyperthreading slowdown issue. This patch is not yet in Linus' tree (it is 
in acpi-test).

Maybe we should drop these patches (10 and 12) until the 3rd patch has been 
merged. I haven't been shipping the 3rd patch in Gentoo (yet) so I'm not able 
to gauge its effect...

Attaching the 3rd patch anyway.

Daniel