From: Nicholas Piggin <npiggin@gmail.com>
To: linuxppc-dev@lists.ozlabs.org
Cc: Nicholas Piggin <npiggin@gmail.com>,
"Gautham R . Shenoy" <ego@linux.vnet.ibm.com>,
Paul Mackerras <paulus@ozlabs.org>
Subject: [PATCH 12/13] powerpc/64s: idle POWER9 can execute stop in virtual mode
Date: Sun, 6 Aug 2017 03:02:40 +1000 [thread overview]
Message-ID: <20170805170241.22966-13-npiggin@gmail.com> (raw)
In-Reply-To: <20170805170241.22966-1-npiggin@gmail.com>
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>
---
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
next prev parent reply other threads:[~2017-08-05 17:03 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-05 17:02 [PATCH 00/13] idle and soft-irq improvements and POWER9 idle optimisation Nicholas Piggin
2017-08-05 17:02 ` [PATCH 01/13] powerpc/64s: masked interrupt avoid branch Nicholas Piggin
2017-08-05 17:02 ` [PATCH 02/13] powerpc/64s: masked interrupt avoid instruction Nicholas Piggin
2017-08-05 17:02 ` [PATCH 03/13] powerpc/64s: masked interrupt returns to kernel so avoid r13 restore Nicholas Piggin
2017-08-05 17:02 ` [PATCH 04/13] powerpc/64: cleanup __check_irq_replay Nicholas Piggin
2017-08-05 17:02 ` [PATCH 05/13] powerpc/64s: irq replay merge HV and non-HV paths for doorbell replay Nicholas Piggin
2017-08-05 17:02 ` [PATCH 06/13] powerpc/64s: irq replay external use the HV handler in HV mode on POWER9 Nicholas Piggin
2017-08-05 17:02 ` [PATCH 07/13] powerpc/64: remove redundant instruction in interrupt replay Nicholas Piggin
2017-08-05 17:02 ` [PATCH 08/13] powerpc/64s: irq replay remove spurious irq reason Nicholas Piggin
2017-08-05 23:00 ` Benjamin Herrenschmidt
2017-08-06 0:51 ` Nicholas Piggin
2017-08-10 13:12 ` Michael Ellerman
2017-08-05 17:02 ` [PATCH 09/13] powerpc/64: runlatch CTRL[RUN] set optimisation Nicholas Piggin
2017-08-05 17:02 ` [PATCH 10/13] powerpc/64s: idle simplify KVM idle on POWER9 Nicholas Piggin
2017-08-05 17:02 ` Nicholas Piggin
2017-08-08 10:36 ` Gautham R Shenoy
2017-08-08 10:48 ` Gautham R Shenoy
2017-08-08 12:42 ` Nicholas Piggin
2017-08-08 12:42 ` Nicholas Piggin
2017-08-10 6:24 ` Gautham R Shenoy
2017-08-10 6:36 ` Gautham R Shenoy
2017-08-10 13:14 ` Michael Ellerman
2017-08-10 13:14 ` Michael Ellerman
2017-08-10 13:53 ` Nicholas Piggin
2017-08-10 13:53 ` Nicholas Piggin
2017-08-05 17:02 ` [PATCH 11/13] powerpc/64s: idle POWER9 can execute stop without ptesync Nicholas Piggin
2017-08-08 10:37 ` Gautham R Shenoy
2017-08-10 13:15 ` Michael Ellerman
2017-08-10 14:03 ` Nicholas Piggin
2017-08-05 17:02 ` Nicholas Piggin [this message]
2017-08-05 22:57 ` [PATCH 12/13] powerpc/64s: idle POWER9 can execute stop in virtual mode Benjamin Herrenschmidt
2017-08-08 10:45 ` Gautham R Shenoy
2017-08-05 17:02 ` [PATCH 13/13] powerpc/64s: idle ESL=0 stop can avoid all save/restore overhead Nicholas Piggin
2017-08-05 17:11 ` Nicholas Piggin
2017-08-08 10:49 ` Gautham R Shenoy
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