From d4e58e5928f8c6c49228451dd03e0714cbab299a Mon Sep 17 00:00:00 2001
From: Michael Neuling <mikey@neuling.org>
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 <mikey@neuling.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---
arch/powerpc/sysdev/xics/icp-native.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
(limited to 'arch/powerpc/sysdev')
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)
--
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