On Fri, Aug 25, 2017 at 02:30:35PM +1000, Nicholas Piggin wrote: > The hardware can execute stop in any context, and KVM does not > require real mode because siblings do not share MMU state. This > saves a switch to real-mode when going idle. > > Acked-by: Gautham R. Shenoy <e...@linux.vnet.ibm.com> > Signed-off-by: Nicholas Piggin <npig...@gmail.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 14e97f442167..32d65ee323a0 100644 > --- a/arch/powerpc/kernel/idle_book3s.S > +++ b/arch/powerpc/kernel/idle_book3s.S > @@ -195,7 +195,16 @@ pnv_powersave_common: > std r5,_CCR(r1) > std r1,PACAR1(r13) > > +BEGIN_FTR_SECTION > + /* > + * POWER9 does not require real mode to stop, and presently 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
... and POWER7 too. Since that's just a comment, Reviewed-by: Paul Mackerras <pau...@ozlabs.org>
