From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-x242.google.com (mail-pg0-x242.google.com [IPv6:2607:f8b0:400e:c05::242]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3xdpBc5pBfzDrK4 for ; Fri, 25 Aug 2017 14:31:04 +1000 (AEST) Received: by mail-pg0-x242.google.com with SMTP id t3so2161998pgt.5 for ; Thu, 24 Aug 2017 21:31:04 -0700 (PDT) From: Nicholas Piggin To: linuxppc-dev@lists.ozlabs.org Cc: Nicholas Piggin , kvm-ppc@vger.kernel.org, Paul Mackerras Subject: [PATCH v3 3/4] powerpc/64s: idle POWER9 can execute stop in virtual mode Date: Fri, 25 Aug 2017 14:30:35 +1000 Message-Id: <20170825043036.18236-4-npiggin@gmail.com> In-Reply-To: <20170825043036.18236-1-npiggin@gmail.com> References: <20170825043036.18236-1-npiggin@gmail.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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 Signed-off-by: Nicholas Piggin --- 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 * 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 -- 2.13.3