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Subject: Re: [PATCH] powerpc/traps: fix recoverability of machine check
 handling on book3s/32
To:     =?UTF-8?Q?Michal_Such=c3=a1nek?= <msuchanek@suse.de>
Cc:     Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Nicholas Piggin <npiggin@gmail.com>,
        linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org
References: <1c804764d38fb084b420b12ca13e8c1b2dea075e.1548166189.git.christophe.leroy@c-s.fr>
 <20200911091542.GE29521@kitsune.suse.cz>
From:   Christophe Leroy <christophe.leroy@csgroup.eu>
Message-ID: <69e1863a-468d-55d7-f2b2-e700b22609a3@csgroup.eu>
Date:   Fri, 11 Sep 2020 11:54:49 +0200
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Hello,

Le 11/09/2020 à 11:15, Michal Suchánek a écrit :
> Hello,
> 
> does this logic apply to "Unrecoverable System Reset" as well?

I don't know, I don't think I have any way the generate a System Reset 
on my board to check it.

Christophe

> 
> 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@c-s.fr>
>> Cc: stable@vger.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
>>