From: Nicholas Piggin <npiggin@gmail.com>
To: linuxppc-dev@lists.ozlabs.org
Cc: Nicholas Piggin <npiggin@gmail.com>,
kvm-ppc@vger.kernel.org, Paul Mackerras <paulus@ozlabs.org>
Subject: [PATCH v3 3/4] powerpc/64s: idle POWER9 can execute stop in virtual mode
Date: Fri, 25 Aug 2017 14:30:35 +1000 [thread overview]
Message-ID: <20170825043036.18236-4-npiggin@gmail.com> (raw)
In-Reply-To: <20170825043036.18236-1-npiggin@gmail.com>
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 <ego@linux.vnet.ibm.com>
Signed-off-by: Nicholas Piggin <npiggin@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
* 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
next prev parent reply other threads:[~2017-08-25 4:31 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-25 4:30 [PATCH v3 0/4] powerpc/64s: idle POWER9 stop improvements Nicholas Piggin
2017-08-25 4:30 ` [PATCH v3 1/4] KVM: PPC: Book3S HV: POWER9 does not require secondary thread management Nicholas Piggin
2017-08-28 11:49 ` Michael Ellerman
2017-08-29 0:13 ` Paul Mackerras
2017-08-31 11:36 ` [v3, " Michael Ellerman
2017-08-25 4:30 ` [PATCH v3 2/4] powerpc/64s: idle POWER9 can execute stop without a sync sequence Nicholas Piggin
2017-08-29 0:11 ` Paul Mackerras
2017-08-29 10:30 ` Michael Ellerman
2017-08-31 11:36 ` [v3, " Michael Ellerman
2017-08-25 4:30 ` Nicholas Piggin [this message]
2017-08-29 0:14 ` [PATCH v3 3/4] powerpc/64s: idle POWER9 can execute stop in virtual mode Paul Mackerras
2017-08-31 11:36 ` [v3, " Michael Ellerman
2017-08-25 4:30 ` [PATCH v3 4/4] powerpc/64s: idle ESL=0 stop can avoid MSR and save/restore overhead Nicholas Piggin
2017-08-29 0:20 ` Paul Mackerras
2017-08-29 1:39 ` Nicholas Piggin
2017-08-30 11:25 ` Michael Ellerman
2017-08-30 12:10 ` Nicholas Piggin
2017-09-01 9:39 ` Michael Ellerman
2017-09-20 13:56 ` Nicholas Piggin
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