linux-kernel - Re: [PATCH v2 2/2] MIPS: CPS: Copy EVA configuration when starting secondary VPs.

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Date:	Wed, 18 May 2016 23:34:57 +0100
From:	Paul Burton <paul.burton@...tec.com>
To:	Matt Redfearn <matt.redfearn@...tec.com>
CC:	Ralf Baechle <ralf@...ux-mips.org>, <linux-mips@...ux-mips.org>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 2/2] MIPS: CPS: Copy EVA configuration when starting
 secondary VPs.

On Wed, May 18, 2016 at 05:12:36PM +0100, Matt Redfearn wrote:
> When starting secondary VPEs which support EVA and the SegCtl registers,
> copy the memory segmentation configuration from the running VPE to ensure
> that all VPEs in the core have a consistent virtual memory map.
> 
> The EVA configuration of secondary cores is dealt with when starting the
> core via the CM.
> 
> Signed-off-by: Matt Redfearn <matt.redfearn@...tec.com>
> ---
> 
> Changes in v2:
> - Skip check for config3 existing - we know it must to be doing
> multithreading
> - Use a unique lable name in the function
> 
>  arch/mips/kernel/cps-vec.S | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)
> 
> diff --git a/arch/mips/kernel/cps-vec.S b/arch/mips/kernel/cps-vec.S
> index ac81edd44563..f8eae9189e38 100644
> --- a/arch/mips/kernel/cps-vec.S
> +++ b/arch/mips/kernel/cps-vec.S
> @@ -431,6 +431,21 @@ LEAF(mips_cps_boot_vpes)
>  	mfc0	t0, CP0_CONFIG
>  	mttc0	t0, CP0_CONFIG
>  
> +	/*
> +	 * Copy the EVA config from this VPE if the CPU supports it.
> +	 * CONFIG3 must exist to be running MT startup - just read it.
> +	 */
> +	mfc0	t0, CP0_CONFIG, 3
> +	and	t0, t0, MIPS_CONF3_SC

Tiny nit - I'd prefer "andi" here since we're using an immediate. The
assembler will figure it out though, so it's not a big deal.

For both in the series:

    Reviewed-by: Paul Burton <paul.burton@...tec.com>

Thanks,
    Paul

> +	beqz	t0, 3f
> +	 nop
> +	mfc0    t0, CP0_SEGCTL0
> +	mttc0	t0, CP0_SEGCTL0
> +	mfc0    t0, CP0_SEGCTL1
> +	mttc0	t0, CP0_SEGCTL1
> +	mfc0    t0, CP0_SEGCTL2
> +	mttc0	t0, CP0_SEGCTL2
> +3:
>  	/* Ensure no software interrupts are pending */
>  	mttc0	zero, CP0_CAUSE
>  	mttc0	zero, CP0_STATUS
> -- 
> 2.5.0
>