linux-kernel - Re: [PATCH] powernv: Clear SPRN_PSSCR when a POWER9 CPU comes online

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Message-ID: <1479861172.6542.62.camel@neuling.org>
Date:   Wed, 23 Nov 2016 11:32:52 +1100
From:   Michael Neuling <mikey@...ling.org>
To:     "Gautham R. Shenoy" <ego@...ux.vnet.ibm.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Vaidyanathan Srinivasan <svaidy@...ux.vnet.ibm.com>,
        "Shreyas B. Prabhu" <shreyasbp@...il.com>
Cc:     linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] powernv: Clear SPRN_PSSCR when a POWER9 CPU comes online

On Tue, 2016-11-22 at 23:36 +0530, Gautham R. Shenoy wrote:
> From: "Gautham R. Shenoy" <ego@...ux.vnet.ibm.com>
> 
> Ensure that PSSCR is set to a safe value corresponding to no
> state-loss each time a POWER9 CPU comes online.
> 
> Signed-off-by: Gautham R. Shenoy <ego@...ux.vnet.ibm.com>

Tested here on my configuration... FWIW

Acked-By: Michael Neuling <mikey@...ling.org>

> ---
>  arch/powerpc/kernel/cpu_setup_power.S | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/arch/powerpc/kernel/cpu_setup_power.S
> b/arch/powerpc/kernel/cpu_setup_power.S
> index 52ff3f0..37ad045 100644
> --- a/arch/powerpc/kernel/cpu_setup_power.S
> +++ b/arch/powerpc/kernel/cpu_setup_power.S
> @@ -96,6 +96,7 @@ _GLOBAL(__setup_cpu_power9)
>  	mtlr	r11
>  	beqlr
>  	li	r0,0
> +	mtspr	SPRN_PSSCR,r0
>  	mtspr	SPRN_LPID,r0
>  	mfspr	r3,SPRN_LPCR
>  	ori	r3, r3, LPCR_PECEDH
> @@ -116,6 +117,7 @@ _GLOBAL(__restore_cpu_power9)
>  	mtlr	r11
>  	beqlr
>  	li	r0,0
> +	mtspr	SPRN_PSSCR,r0
>  	mtspr	SPRN_LPID,r0
>  	mfspr   r3,SPRN_LPCR
>  	ori	r3, r3, LPCR_PECEDH