linux-kernel - [PATCH 2/3] powernv:idle: Decouple TB restore & Per-core SPRs restore

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Message-Id: <27511c1235ee58c66eabdea65b39f5dd35d91426.1491996797.git.ego@linux.vnet.ibm.com>
Date:   Wed, 12 Apr 2017 17:16:21 +0530
From:   "Gautham R. Shenoy" <ego@...ux.vnet.ibm.com>
To:     Michael Ellerman <mpe@...erman.id.au>,
        Michael Neuling <mikey@...ling.org>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        "Shreyas B. Prabhu" <shreyasbp@...il.com>,
        Shilpasri G Bhat <shilpa.bhat@...ux.vnet.ibm.com>,
        Vaidyanathan Srinivasan <svaidy@...ux.vnet.ibm.com>,
        Anton Blanchard <anton@...ba.org>,
        Balbir Singh <bsingharora@...il.com>,
        Akshay Adiga <akshay.adiga@...ux.vnet.ibm.com>,
        Nicholas Piggin <npiggin@...il.com>,
        Mahesh J Salgaonkar <mahesh@...ux.vnet.ibm.com>,
        "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>
Cc:     linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        "Gautham R. Shenoy" <ego@...ux.vnet.ibm.com>
Subject: [PATCH 2/3] powernv:idle: Decouple TB restore & Per-core SPRs restore

From: "Gautham R. Shenoy" <ego@...ux.vnet.ibm.com>

The idle-exit code assumes that if Timebase is not lost, then neither
are the per-core hypervisor resources lost. This was true on POWER8
where fast-sleep lost only TB but not per-core resources, and winkle
lost both.

This assumption is not true for POWER9 however, since there can be
states which do not lose timebase but can lose per-core SPRs.

Hence check if we need to restore the per-core hypervisor state even
if timebase is not lost.

Signed-off-by: Gautham R. Shenoy <ego@...ux.vnet.ibm.com>
---
 arch/powerpc/kernel/idle_book3s.S | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/kernel/idle_book3s.S b/arch/powerpc/kernel/idle_book3s.S
index 9b747e9..6a9bd28 100644
--- a/arch/powerpc/kernel/idle_book3s.S
+++ b/arch/powerpc/kernel/idle_book3s.S
@@ -723,13 +723,14 @@ timebase_resync:
 	 * Use cr3 which indicates that we are waking up with atleast partial
 	 * hypervisor state loss to determine if TIMEBASE RESYNC is needed.
 	 */
-	ble	cr3,clear_lock
+	ble	cr3,.Ltb_resynced
 	/* Time base re-sync */
 	bl	opal_resync_timebase;
 	/*
-	 * If waking up from sleep, per core state is not lost, skip to
-	 * clear_lock.
+	 * If waking up from sleep (POWER8), per core state
+	 * is not lost, skip to clear_lock.
 	 */
+.Ltb_resynced:
 	blt	cr4,clear_lock
 
 	/*
-- 
1.9.4