linux-kernel - Re: [PATCH] powerpc/traps: fix recoverability of machine check handling on book3s/32

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Message-ID: <20200911091542.GE29521@kitsune.suse.cz>
Date:   Fri, 11 Sep 2020 11:15:42 +0200
From:   Michal Suchánek <msuchanek@...e.de>
To:     Christophe Leroy <christophe.leroy@....fr>
Cc:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Nicholas Piggin <npiggin@...il.com>,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] powerpc/traps: fix recoverability of machine check
 handling on book3s/32

Hello,

does this logic apply to "Unrecoverable System Reset" as well?

Thanks

Michal

On Tue, Jan 22, 2019 at 02:11:24PM +0000, Christophe Leroy wrote:
> Looks like book3s/32 doesn't set RI on machine check, so
> checking RI before calling die() will always be fatal
> allthought this is not an issue in most cases.
> 
> Fixes: b96672dd840f ("powerpc: Machine check interrupt is a non-maskable interrupt")
> Fixes: daf00ae71dad ("powerpc/traps: restore recoverability of machine_check interrupts")
> Signed-off-by: Christophe Leroy <christophe.leroy@....fr>
> Cc: stable@...r.kernel.org
> ---
>  arch/powerpc/kernel/traps.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
> index 64936b60d521..c740f8bfccc9 100644
> --- a/arch/powerpc/kernel/traps.c
> +++ b/arch/powerpc/kernel/traps.c
> @@ -763,15 +763,15 @@ void machine_check_exception(struct pt_regs *regs)
>  	if (check_io_access(regs))
>  		goto bail;
>  
> -	/* Must die if the interrupt is not recoverable */
> -	if (!(regs->msr & MSR_RI))
> -		nmi_panic(regs, "Unrecoverable Machine check");
> -
>  	if (!nested)
>  		nmi_exit();
>  
>  	die("Machine check", regs, SIGBUS);
>  
> +	/* Must die if the interrupt is not recoverable */
> +	if (!(regs->msr & MSR_RI))
> +		nmi_panic(regs, "Unrecoverable Machine check");
> +
>  	return;
>  
>  bail:
> -- 
> 2.13.3
>