[PATCH] KVM: PPC: Don't sync timebase when inside KVM

[Alexander Graf]

When we know that we're running inside of a KVM guest, we don't have to
worry about synchronizing timebases between different CPUs, since the
host already took care of that.

This fixes CPU overcommit scenarios where vCPUs could hang forever trying
to sync each other while not being scheduled.

Reported-by: Stuart Yoder <B08248 at freescale.com>
Signed-off-by: Alexander Graf <agraf at suse.de>
---
 arch/powerpc/kernel/smp.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index 46695fe..670b453 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -49,6 +49,8 @@
 #ifdef CONFIG_PPC64
 #include <asm/paca.h>
 #endif
+#include <linux/kvm_para.h>
+#include <asm/kvm_para.h>
 
 #ifdef DEBUG
 #include <asm/udbg.h>
@@ -541,7 +543,7 @@ int __cpuinit __cpu_up(unsigned int cpu)
 
 	DBG("Processor %u found.\n", cpu);
 
-	if (smp_ops->give_timebase)
+	if (!kvm_para_available() && smp_ops->give_timebase)
 		smp_ops->give_timebase();
 
 	/* Wait until cpu puts itself in the online map */
@@ -626,7 +628,7 @@ void __devinit start_secondary(void *unused)
 
 	if (smp_ops->setup_cpu)
 		smp_ops->setup_cpu(cpu);
-	if (smp_ops->take_timebase)
+	if (!kvm_para_available() && smp_ops->take_timebase)
 		smp_ops->take_timebase();
 
 	secondary_cpu_time_init();
-- 
1.6.0.2