On Fri, 2012-07-27 at 09:53 +1000, Paul Mackerras wrote:
> The CPU hotplug code for the powernv platform currently only puts
> offline CPUs into nap mode if the powersave_nap variable is set.
> However, HV-style KVM on this platform requires secondary CPU threads
> to be offline and in nap mode. Since we know nap mode works just
> fine on all POWER7 machines, and the only machines that support the
> powernv platform are POWER7 machines, this changes the code to
> always put offline CPUs into nap mode, regardless of powersave_nap.
> Powersave_nap still controls whether or not CPUs go into nap mode
> when idle, as before.
>
> Signed-off-by: Paul Mackerras <pau...@samba.org>
I assume this should go in now and -stable ?
Cheers,
Ben.
> ---
> arch/powerpc/include/asm/processor.h | 1 +
> arch/powerpc/kernel/idle_power7.S | 2 ++
> arch/powerpc/platforms/powernv/smp.c | 10 +---------
> 3 files changed, 4 insertions(+), 9 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/processor.h
> b/arch/powerpc/include/asm/processor.h
> index 2a25ab0..42d3869 100644
> --- a/arch/powerpc/include/asm/processor.h
> +++ b/arch/powerpc/include/asm/processor.h
> @@ -390,6 +390,7 @@ enum idle_boot_override {IDLE_NO_OVERRIDE = 0,
> IDLE_POWERSAVE_OFF};
>
> extern int powersave_nap; /* set if nap mode can be used in idle loop */
> void cpu_idle_wait(void);
> +extern void power7_nap(void);
>
> #ifdef CONFIG_PSERIES_IDLE
> extern void update_smt_snooze_delay(int snooze);
> diff --git a/arch/powerpc/kernel/idle_power7.S
> b/arch/powerpc/kernel/idle_power7.S
> index 7140d83..e11863f 100644
> --- a/arch/powerpc/kernel/idle_power7.S
> +++ b/arch/powerpc/kernel/idle_power7.S
> @@ -28,7 +28,9 @@ _GLOBAL(power7_idle)
> lwz r4,ADDROFF(powersave_nap)(r3)
> cmpwi 0,r4,0
> beqlr
> + /* fall through */
>
> +_GLOBAL(power7_nap)
> /* NAP is a state loss, we create a regs frame on the
> * stack, fill it up with the state we care about and
> * stick a pointer to it in PACAR1. We really only
> diff --git a/arch/powerpc/platforms/powernv/smp.c
> b/arch/powerpc/platforms/powernv/smp.c
> index 3ef4625..7698b6e 100644
> --- a/arch/powerpc/platforms/powernv/smp.c
> +++ b/arch/powerpc/platforms/powernv/smp.c
> @@ -106,14 +106,6 @@ static void pnv_smp_cpu_kill_self(void)
> {
> unsigned int cpu;
>
> - /* If powersave_nap is enabled, use NAP mode, else just
> - * spin aimlessly
> - */
> - if (!powersave_nap) {
> - generic_mach_cpu_die();
> - return;
> - }
> -
> /* Standard hot unplug procedure */
> local_irq_disable();
> idle_task_exit();
> @@ -128,7 +120,7 @@ static void pnv_smp_cpu_kill_self(void)
> */
> mtspr(SPRN_LPCR, mfspr(SPRN_LPCR) & ~(u64)LPCR_PECE1);
> while (!generic_check_cpu_restart(cpu)) {
> - power7_idle();
> + power7_nap();
> if (!generic_check_cpu_restart(cpu)) {
> DBG("CPU%d Unexpected exit while offline !\n", cpu);
> /* We may be getting an IPI, so we re-enable
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