Commit d4e58e59 authored by Michael Neuling's avatar Michael Neuling Committed by Benjamin Herrenschmidt
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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
......@@ -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
......
......@@ -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
......
......@@ -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)
......
......@@ -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
......
......@@ -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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