From ec4867355244755fb5c06037ad2fff760701b465 Mon Sep 17 00:00:00 2001
From: "Gautham R. Shenoy" <ego@linux.vnet.ibm.com>
Date: Tue, 16 May 2017 14:19:44 +0530
Subject: [PATCH] powerpc/powernv/idle: Decouple Timebase restore & Per-core
SPRs restore
References: bsc#1055121
Patch-mainline: v4.13-rc1
Git-commit: ec4867355244755fb5c06037ad2fff760701b465
On POWER8, in case of
- nap: both timebase and hypervisor state is retained.
- fast-sleep: timebase is lost. But the hypervisor state is retained.
- winkle: timebase and hypervisor state is lost.
Hence, the current code for handling exit from a idle state assumes
that if the timebase value is retained, then so is the hypervisor
state. Thus, the current code doesn't restore per-core hypervisor
state in such cases.
But that is no longer the case on POWER9 where we do have stop states
in which timebase value is retained, but the hypervisor state is
lost. So we have to ensure that the per-core hypervisor state gets
restored in such cases.
Fix this by ensuring that even in the case when timebase is retained,
we explicitly check if we are waking up from a deep stop that loses
per-core hypervisor state (indicated by cr4 being eq or gt), and if
this is the case, we restore the per-core hypervisor state.
Signed-off-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Acked-by: Michal Suchanek <msuchanek@suse.de>
---
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 4898d676dcae..afd029f1039b 100644
--- a/arch/powerpc/kernel/idle_book3s.S
+++ b/arch/powerpc/kernel/idle_book3s.S
@@ -731,13 +731,14 @@ 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
/*
--
2.10.2