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Commit d4e58e59 authored by Michael Neuling's avatar Michael Neuling Committed by Benjamin Herrenschmidt
Browse files

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: default avatarMichael Neuling <mikey@neuling.org>
Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
parent 9b6a68d9

arch/powerpc/kernel/cpu_setup_power.S

+2 −0
Original line number Diff line number Diff line
@@ -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

arch/powerpc/platforms/powernv/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -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

arch/powerpc/platforms/powernv/smp.c

+6 −0
Original line number Diff line number Diff line
@@ -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)

arch/powerpc/platforms/pseries/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -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

arch/powerpc/sysdev/xics/icp-native.c

+8 −1
Original line number Diff line number Diff line
@@ -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 {
@@ -145,6 +146,12 @@ 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);

#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);

}