[RFC PATCH 8/9] powerpc: Support to replay PMIs

[Nicholas Piggin]

On Mon, 25 Jul 2016 20:22:21 +0530
Madhavan Srinivasan <maddy at linux.vnet.ibm.com> wrote:

> Code to replay the Performance Monitoring Interrupts(PMI).
> In the masked_interrupt handler, for PMIs we reset the MSR[EE]
> and return. This is due the fact that PMIs are level triggered.
> In the __check_irq_replay(), we enabled the MSR[EE] which will
> fire the interrupt for us.
> 
> Patch also adds a new arch_local_irq_disable_var() variant. New
> variant takes an input value to write to the paca->soft_enabled.
> This will be used in following patch to implement the tri-state
> value for soft-enabled.

Same comment also applies about patches being standalone
transformations that work before and after. Some of these
can be squashed together I think.


> Signed-off-by: Madhavan Srinivasan <maddy at linux.vnet.ibm.com>
> ---
>  arch/powerpc/include/asm/hw_irq.h | 14 ++++++++++++++
>  arch/powerpc/kernel/irq.c         |  9 ++++++++-
>  2 files changed, 22 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/powerpc/include/asm/hw_irq.h
> b/arch/powerpc/include/asm/hw_irq.h index cc69dde6eb84..863179654452
> 100644 --- a/arch/powerpc/include/asm/hw_irq.h
> +++ b/arch/powerpc/include/asm/hw_irq.h
> @@ -81,6 +81,20 @@ static inline unsigned long
> arch_local_irq_disable(void) return flags;
>  }
>  
> +static inline unsigned long arch_local_irq_disable_var(int value)
> +{
> +	unsigned long flags, zero;
> +
> +	asm volatile(
> +		"li %1,%3; lbz %0,%2(13); stb %1,%2(13)"
> +		: "=r" (flags), "=&r" (zero)
> +		: "i" (offsetof(struct paca_struct, soft_enabled)),\
> +		  "i" (value)
> +		: "memory");
> +
> +	return flags;
> +}

arch_ function suggests it is arch implementation of a generic
kernel function or something. I think our soft interrupt levels
are just used in powerpc specific code.

The name could also be a little more descriptive.

I would have our internal function be something like

soft_irq_set_level(), and then the arch disable just sets to
the appropriate level as it does today.

The PMU disable level could be implemented in powerpc specific
header with local_irq_and_pmu_disable() or something like that.

Thanks,
Nick