Re: [PATCH 12/13] powerpc/64s: idle POWER9 can execute stop in virtual mode
From: Gautham R Shenoy <hidden>
Date: 2017-08-08 10:45:42
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 <npiggin@gmail.com>
Acked-by: Gautham R. Shenoy <redacted>
quoted hunk ↗ jump to hunk
--- 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