linux-kernel - Re: [PATCH v1 5/5] powerpc/epapr: Don't use wrteei on non booke

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Date:   Tue, 20 Dec 2022 21:21:11 +0100
From:   Pali Rohár <pali@...nel.org>
To:     Christophe Leroy <christophe.leroy@...roup.eu>
Cc:     Michael Ellerman <mpe@...erman.id.au>,
        Nicholas Piggin <npiggin@...il.com>, jbglaw@...-owl.de,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 5/5] powerpc/epapr: Don't use wrteei on non booke

On Monday 19 December 2022 19:46:00 Christophe Leroy wrote:
> wrteei is only for booke. Use the standard mfmsr/ori/mtmsr
> when non booke.
> 
> Reported-by: Jan-Benedict Glaw <jbglaw@...-owl.de>
> Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
> ---
> Not sure this is needed at all, the commit that introduced the code says it is for e500, but there's no such limitation in Kconfig. Maybe we should limit all the file to CONFIG_PPC_E500

This ePAPR code is according to ePAPR v1.1. So it does not have to be
e500 specific. But is there anything else in this category?

> ---
>  arch/powerpc/kernel/epapr_hcalls.S | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/arch/powerpc/kernel/epapr_hcalls.S b/arch/powerpc/kernel/epapr_hcalls.S
> index 69a912550577..033116e465d0 100644
> --- a/arch/powerpc/kernel/epapr_hcalls.S
> +++ b/arch/powerpc/kernel/epapr_hcalls.S
> @@ -21,7 +21,13 @@ _GLOBAL(epapr_ev_idle)
>  	ori	r4, r4,_TLF_NAPPING	/* so when we take an exception */
>  	PPC_STL	r4, TI_LOCAL_FLAGS(r2)	/* it will return to our caller */
>  
> +#ifdef CONFIG_BOOKE_OR_40x
>  	wrteei	1
> +#else
> +	mfmsr	r4
> +	ori	r4, r4, MSR_EE
> +	mtmsr	r4
> +#endif
>  
>  idle_loop:
>  	LOAD_REG_IMMEDIATE(r11, EV_HCALL_TOKEN(EV_IDLE))
> -- 
> 2.38.1
>