From d4e58e5928f8c6c49228451dd03e0714cbab299a Mon Sep 17 00:00:00 2001 From: Michael Neuling Date: Wed, 11 Jun 2014 15:59:28 +1000 Subject: [PATCH] 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/kernel/cpu_setup_power.S | 2 ++ arch/powerpc/platforms/powernv/Kconfig | 1 + arch/powerpc/platforms/powernv/smp.c | 6 ++++++ arch/powerpc/platforms/pseries/Kconfig | 1 + arch/powerpc/sysdev/xics/icp-native.c | 9 ++++++++- 5 files changed, 18 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/kernel/cpu_setup_power.S b/arch/powerpc/kernel/cpu_setup_power.S index 1557e7c2c7e1..46733535cc0b 100644 --- a/arch/powerpc/kernel/cpu_setup_power.S +++ b/arch/powerpc/kernel/cpu_setup_power.S @@ -56,6 +56,7 @@ _GLOBAL(__setup_cpu_power8) li r0,0 mtspr SPRN_LPID,r0 mfspr r3,SPRN_LPCR + ori r3, r3, LPCR_PECEDH bl __init_LPCR bl __init_HFSCR bl __init_tlb_power8 @@ -74,6 +75,7 @@ _GLOBAL(__restore_cpu_power8) li r0,0 mtspr SPRN_LPID,r0 mfspr r3,SPRN_LPCR + ori r3, r3, LPCR_PECEDH bl __init_LPCR bl __init_HFSCR bl __init_tlb_power8 diff --git a/arch/powerpc/platforms/powernv/Kconfig b/arch/powerpc/platforms/powernv/Kconfig index c252ee95bddf..45a8ed0585cd 100644 --- a/arch/powerpc/platforms/powernv/Kconfig +++ b/arch/powerpc/platforms/powernv/Kconfig @@ -17,6 +17,7 @@ config PPC_POWERNV select CPU_FREQ_GOV_USERSPACE select CPU_FREQ_GOV_ONDEMAND select CPU_FREQ_GOV_CONSERVATIVE + select PPC_DOORBELL default y config PPC_POWERNV_RTAS diff --git a/arch/powerpc/platforms/powernv/smp.c b/arch/powerpc/platforms/powernv/smp.c index 0062a43a2e0d..5fcfcf44e3a9 100644 --- a/arch/powerpc/platforms/powernv/smp.c +++ b/arch/powerpc/platforms/powernv/smp.c @@ -32,6 +32,7 @@ #include #include #include +#include #include "powernv.h" @@ -46,6 +47,11 @@ static void pnv_smp_setup_cpu(int cpu) { if (cpu != boot_cpuid) xics_setup_cpu(); + +#ifdef CONFIG_PPC_DOORBELL + if (cpu_has_feature(CPU_FTR_DBELL)) + doorbell_setup_this_cpu(); +#endif } int pnv_smp_kick_cpu(int nr) diff --git a/arch/powerpc/platforms/pseries/Kconfig b/arch/powerpc/platforms/pseries/Kconfig index 2cb8b776c84a..756b482f819a 100644 --- a/arch/powerpc/platforms/pseries/Kconfig +++ b/arch/powerpc/platforms/pseries/Kconfig @@ -21,6 +21,7 @@ config PPC_PSERIES select HAVE_CONTEXT_TRACKING select HOTPLUG_CPU if SMP select ARCH_RANDOM + select PPC_DOORBELL default y config PPC_SPLPAR 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) -- 2.20.1