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authorMichael Neuling <mikey@neuling.org>2014-06-11 09:59:28 +0400
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2014-06-11 11:05:12 +0400
commitd4e58e5928f8c6c49228451dd03e0714cbab299a (patch)
tree34add9a16b4dbe03da04191f51588f3f6a6bdbf9 /arch
parent9b6a68d94333cf19d4ec0f2aaf9f9eb68866630e (diff)
downloadlinux-d4e58e5928f8c6c49228451dd03e0714cbab299a.tar.xz
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 <mikey@neuling.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'arch')
-rw-r--r--arch/powerpc/kernel/cpu_setup_power.S2
-rw-r--r--arch/powerpc/platforms/powernv/Kconfig1
-rw-r--r--arch/powerpc/platforms/powernv/smp.c6
-rw-r--r--arch/powerpc/platforms/pseries/Kconfig1
-rw-r--r--arch/powerpc/sysdev/xics/icp-native.c9
5 files changed, 18 insertions, 1 deletions
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 <asm/opal.h>
#include <asm/runlatch.h>
#include <asm/code-patching.h>
+#include <asm/dbell.h>
#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 <asm/errno.h>
#include <asm/xics.h>
#include <asm/kvm_ppc.h>
+#include <asm/dbell.h>
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)