Subject: Re: [PATCH 5/7] powerpc/ppc64: Do not turn AIL (reloc-on interrupts) too early

From: Michael Neuling <[email-masked]>
Date: Fri, 11 Apr 2014 16:52:50 +1000

Benjamin Herrenschmidt <[email-masked]> wrote:

> Turn them on at the same time as we allow MSR_IR/DR in the paca
> kernel MSR, ie, after the MMU has been setup enough to be able
> to handle relocated access to the linear mapping.
> 
> Signed-off-by: Benjamin Herrenschmidt <[email-masked]>
> ---
>  arch/powerpc/kernel/cpu_setup_power.S |  2 --
>  arch/powerpc/kernel/setup_64.c        | 18 +++++++++++++++---
>  2 files changed, 15 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/powerpc/kernel/cpu_setup_power.S b/arch/powerpc/kernel/cpu_setup_power.S
> index 37d1bb0..1557e7c 100644
> --- a/arch/powerpc/kernel/cpu_setup_power.S
> +++ b/arch/powerpc/kernel/cpu_setup_power.S
> @@ -56,7 +56,6 @@ _GLOBAL(__setup_cpu_power8)
>  	li	r0,0
>  	mtspr	SPRN_LPID,r0
>  	mfspr	r3,SPRN_LPCR
> -	oris	r3, r3, LPCR_AIL_3@h
>  	bl	__init_LPCR
>  	bl	__init_HFSCR
>  	bl	__init_tlb_power8
> @@ -75,7 +74,6 @@ _GLOBAL(__restore_cpu_power8)
>  	li	r0,0
>  	mtspr	SPRN_LPID,r0
>  	mfspr   r3,SPRN_LPCR
> -	oris	r3, r3, LPCR_AIL_3@h
>  	bl	__init_LPCR
>  	bl	__init_HFSCR
>  	bl	__init_tlb_power8

BTW with this we can put the   	"mfspr   r3,SPRN_LPCR" in __init_LPCR
and clean this code up bit.

Mikey

> diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
> index 1d33e81..3d7a50a 100644
> --- a/arch/powerpc/kernel/setup_64.c
> +++ b/arch/powerpc/kernel/setup_64.c
> @@ -195,6 +195,18 @@ static void fixup_boot_paca(void)
>  	get_paca()->data_offset = 0;
>  }
>  
> +static void cpu_ready_for_interrupts(void)
> +{
> +	/* Set IR and DR in PACA MSR */
> +	get_paca()->kernel_msr = MSR_KERNEL;
> +
> +	/* Enable AIL if supported */
> +	if (cpu_has_feature(CPU_FTR_ARCH_207S)) {
> +		unsigned long lpcr = mfspr(SPRN_LPCR);
> +		mtspr(SPRN_LPCR, lpcr | LPCR_AIL_3);
> +	}
> +}
> +
>  /*
>   * Early initialization entry point. This is called by head.S
>   * with MMU translation disabled. We rely on the "feature" of
> @@ -264,9 +276,9 @@ void __init early_setup(unsigned long dt_ptr)
>  	/*
>  	 * At this point, we can let interrupts switch to virtual mode
>  	 * (the MMU has been setup), so adjust the MSR in the PACA to
> -	 * have IR and DR set.
> +	 * have IR and DR set and enable AIL if it exists
>  	 */
> -	get_paca()->kernel_msr = MSR_KERNEL;
> +	cpu_ready_for_interrupts();
>  
>  	/* Reserve large chunks of memory for use by CMA for KVM */
>  	kvm_cma_reserve();
> @@ -307,7 +319,7 @@ void early_setup_secondary(void)
>  	 * (the MMU has been setup), so adjust the MSR in the PACA to
>  	 * have IR and DR set.
>  	 */
> -	get_paca()->kernel_msr = MSR_KERNEL;
> +	cpu_ready_for_interrupts();
>  }
>  
>  #endif /* CONFIG_SMP */
> -- 
> 1.8.3.2
> 
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