From patchwork Wed Feb 29 02:16:09 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: KVM: PPC: Don't sync timebase when inside KVM Date: Tue, 28 Feb 2012 16:16:09 -0000 From: Alexander Graf X-Patchwork-Id: 143657 Message-Id: <1330481769-24390-1-git-send-email-agraf@suse.de> To: kvm-ppc@vger.kernel.org Cc: kvm@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, Scott Wood , Stuart Yoder 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 Signed-off-by: Alexander Graf --- 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 #endif +#include +#include #ifdef DEBUG #include @@ -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();