From d4e58e5928f8c6c49228451dd03e0714cbab299a Mon Sep 17 00:00:00 2001 From: Michael Neuling Date: Wed, 11 Jun 2014 15:59:28 +1000 Subject: powerpc/powernv: Enable POWER8 doorbell IPIs This patch enables POWER8 doorbell IPIs on powernv. Since doorbells can only IPI within a core, we test to see when we can use doorbells and if not we fall back to XICS. This also enables hypervisor doorbells to wakeup us up from nap/sleep via the LPCR PECEDH bit. Based on tests by Anton, the best case IPI latency between two threads dropped from 894ns to 512ns. Signed-off-by: Michael Neuling Signed-off-by: Benjamin Herrenschmidt --- arch/powerpc/sysdev/xics/icp-native.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) (limited to 'arch/powerpc/sysdev/xics') diff --git a/arch/powerpc/sysdev/xics/icp-native.c b/arch/powerpc/sysdev/xics/icp-native.c index 9dee47071af8..de8d9483bbe8 100644 --- a/arch/powerpc/sysdev/xics/icp-native.c +++ b/arch/powerpc/sysdev/xics/icp-native.c @@ -26,6 +26,7 @@ #include #include #include +#include struct icp_ipl { union { @@ -145,7 +146,13 @@ static unsigned int icp_native_get_irq(void) static void icp_native_cause_ipi(int cpu, unsigned long data) { kvmppc_set_host_ipi(cpu, 1); - icp_native_set_qirr(cpu, IPI_PRIORITY); +#ifdef CONFIG_PPC_DOORBELL + if (cpu_has_feature(CPU_FTR_DBELL) && + (cpumask_test_cpu(cpu, cpu_sibling_mask(smp_processor_id())))) + doorbell_cause_ipi(cpu, data); + else +#endif + icp_native_set_qirr(cpu, IPI_PRIORITY); } void xics_wake_cpu(int cpu) -- cgit v1.2.1