On Sun, Aug 06, 2017 at 03:02:40AM +1000, Nicholas Piggin wrote:
> The hardware can execute stop in any context, and KVM does not
> require real mode. This saves a switch to real-mode when going
> idle.
> 
> Signed-off-by: Nicholas Piggin <npig...@gmail.com>

Acked-by: Gautham R. Shenoy <e...@linux.vnet.ibm.com>

> ---
>  arch/powerpc/kernel/idle_book3s.S | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/arch/powerpc/kernel/idle_book3s.S 
> b/arch/powerpc/kernel/idle_book3s.S
> index 75746111e2c4..8ac366a51bb5 100644
> --- a/arch/powerpc/kernel/idle_book3s.S
> +++ b/arch/powerpc/kernel/idle_book3s.S
> @@ -141,7 +141,16 @@ pnv_powersave_common:
>       std     r5,_CCR(r1)
>       std     r1,PACAR1(r13)
> 
> +BEGIN_FTR_SECTION
> +     /*
> +      * POWER9 does not require real mode to stop, and does not set
> +      * hwthread_state for KVM (threads don't share MMU context), so
> +      * we can remain in virtual mode for this.
> +      */
> +     bctr
> +END_FTR_SECTION_IFSET(CPU_FTR_ARCH_300)
>       /*
> +      * POWER8
>        * Go to real mode to do the nap, as required by the architecture.
>        * Also, we need to be in real mode before setting hwthread_state,
>        * because as soon as we do that, another thread can switch
> -- 
> 2.11.0
> 

Reply via email to