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Message-ID: <1438388082.19345.85.camel@freescale.com>
Date: Fri, 31 Jul 2015 19:14:42 -0500
From: Scott Wood <scottwood@...escale.com>
To: <b29983@...escale.com>
CC: <b07421@...escale.com>, <linux-kernel@...r.kernel.org>,
Tang Yuantian <Yuantian.Tang@...escale.com>,
Chenhui Zhao <chenhui.zhao@...escale.com>,
Tang Yuantian <Yuantian.Tang@...scale.com>
Subject: Re: [PATCH 2/3] PowerPC/mpc85xx: Add hotplug support on E5500 and
E500MC cores
On Fri, 2015-07-31 at 17:20 +0800, b29983@...escale.com wrote:
> From: Tang Yuantian <Yuantian.Tang@...escale.com>
>
> Freescale E500MC and E5500 core-based platforms, like P4080, T1040,
> support disabling/enabling CPU dynamically.
> This patch adds this feature on those platforms.
>
> Signed-off-by: Chenhui Zhao <chenhui.zhao@...escale.com>
> Signed-off-by: Tang Yuantian <Yuantian.Tang@...scale.com>
> ---
> arch/powerpc/Kconfig | 2 +-
> arch/powerpc/include/asm/smp.h | 1 +
> arch/powerpc/kernel/smp.c | 5 +++++
> arch/powerpc/platforms/85xx/smp.c | 39 ++++++++++++++++++++++++++++++++----
> ---
> 4 files changed, 39 insertions(+), 8 deletions(-)
>
> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> index 5ef2711..dd9e252 100644
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -386,7 +386,7 @@ config SWIOTLB
> config HOTPLUG_CPU
> bool "Support for enabling/disabling CPUs"
> depends on SMP && (PPC_PSERIES || \
> - PPC_PMAC || PPC_POWERNV || (PPC_85xx && !PPC_E500MC))
> + PPC_PMAC || PPC_POWERNV || FSL_SOC_BOOKE)
> ---help---
> Say Y here to be able to disable and re-enable individual
> CPUs at runtime on SMP machines.
> diff --git a/arch/powerpc/include/asm/smp.h b/arch/powerpc/include/asm/smp.h
> index 825663c..bf37d17 100644
> --- a/arch/powerpc/include/asm/smp.h
> +++ b/arch/powerpc/include/asm/smp.h
> @@ -67,6 +67,7 @@ void generic_cpu_die(unsigned int cpu);
> void generic_set_cpu_dead(unsigned int cpu);
> void generic_set_cpu_up(unsigned int cpu);
> int generic_check_cpu_restart(unsigned int cpu);
> +int generic_check_cpu_dead(unsigned int cpu);
> #endif
>
> #ifdef CONFIG_PPC64
> diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
> index ec9ec20..2cca27a 100644
> --- a/arch/powerpc/kernel/smp.c
> +++ b/arch/powerpc/kernel/smp.c
> @@ -454,6 +454,11 @@ int generic_check_cpu_restart(unsigned int cpu)
> return per_cpu(cpu_state, cpu) == CPU_UP_PREPARE;
> }
>
> +int generic_check_cpu_dead(unsigned int cpu)
> +{
> + return per_cpu(cpu_state, cpu) == CPU_DEAD;
> +}
Is there a non-generic check_cpu_dead()?
It gets open-coded in generic_cpu_die()... Either open-code it elsewhere, or
call it check_cpu_dead() and use it everywhere there's a CPU_DEAD check.
> +
> static bool secondaries_inhibited(void)
> {
> return kvm_hv_mode_active();
> diff --git a/arch/powerpc/platforms/85xx/smp.c
> b/arch/powerpc/platforms/85xx/smp.c
> index 6811a5b..7f0dadb 100644
> --- a/arch/powerpc/platforms/85xx/smp.c
> +++ b/arch/powerpc/platforms/85xx/smp.c
> @@ -42,6 +42,7 @@ struct epapr_spin_table {
> u32 pir;
> };
>
> +#ifdef CONFIG_HOTPLUG_CPU
> static u64 timebase;
> static int tb_req;
> static int tb_valid;
> @@ -111,7 +112,7 @@ static void mpc85xx_take_timebase(void)
> local_irq_restore(flags);
> }
>
> -#ifdef CONFIG_HOTPLUG_CPU
> +#ifndef CONFIG_PPC_E500MC
> static void e500_cpu_idle(void)
What happens if we bisect to patch 1/3 and run this on e500mc?
Please move the ifdef to that patch.
> {
> u32 tmp;
> @@ -127,6 +128,7 @@ static void e500_cpu_idle(void)
> mtmsr(tmp);
> isync();
> }
> +#endif
>
> static void qoriq_cpu_dying(void)
> {
> @@ -144,11 +146,30 @@ static void qoriq_cpu_dying(void)
>
> generic_set_cpu_dead(cpu);
>
> +#ifndef CONFIG_PPC_E500MC
> e500_cpu_idle();
> +#endif
>
> while (1)
> ;
> }
> +
> +static void qoriq_real_cpu_die(unsigned int cpu)
Real as opposed to...?
> +{
> + int i;
> +
> + for (i = 0; i < 50000; i++) {
> + if (generic_check_cpu_dead(cpu)) {
> + qoriq_pm_ops->cpu_die(cpu);
> +#ifdef CONFIG_PPC64
> + paca[cpu].cpu_start = 0;
> +#endif
> + return;
> + }
> + udelay(10);
> + }
> + pr_err("%s: CPU%d didn't die...\n", __func__, cpu);
> +}
Only 500ms timeout, versus 10sec in generic_cpu_die()?
> #endif
>
> static inline void flush_spin_table(void *spin_table)
> @@ -246,11 +267,7 @@ static int smp_85xx_kick_cpu(int nr)
> spin_table = phys_to_virt(*cpu_rel_addr);
>
> local_irq_save(flags);
> -#ifdef CONFIG_PPC32
> #ifdef CONFIG_HOTPLUG_CPU
> - /* Corresponding to generic_set_cpu_dead() */
> - generic_set_cpu_up(nr);
> -
> if (system_state == SYSTEM_RUNNING) {
> /*
> * To keep it compatible with old boot program which uses
> @@ -263,6 +280,7 @@ static int smp_85xx_kick_cpu(int nr)
> out_be32(&spin_table->addr_l, 0);
> flush_spin_table(spin_table);
>
> + qoriq_pm_ops->cpu_up(nr);
Again, is it possible to get here without a valid qoriq_pm_ops (i.e. is there
anything stopping the user from trying to initiate CPU hotplug)?
-Scott
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