Re: [PATCH] powerpc/traps: restore recoverability of machine_check interrupts

[Christophe LEROY]

Cc: stable@xxxxxxxxxxxxxxx <stable@xxxxxxxxxxxxxxx>

Le 13/10/2018 Ã 11:16, Christophe Leroy a ÃcritÂ:
> commit b96672dd840f ("powerpc: Machine check interrupt is a non-
> maskable interrupt") added a call to nmi_enter() at the beginning of
> machine check restart exception handler. Due to that, in_interrupt()
> always returns true regardless of the state before entering the
> exception, and die() panics even when the system was not already in
> interrupt.
>
> This patch calls nmi_exit() before calling die() in order to restore
> the interrupt state we had before calling nmi_enter()
>
> Fixes: b96672dd840f ("powerpc: Machine check interrupt is a non-maskable interrupt")
> Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxx>
> ---
>   arch/powerpc/kernel/traps.c | 9 +++++++--
>   1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
> index fd58749b4d6b..4f880c2a6e4c 100644
> --- a/arch/powerpc/kernel/traps.c
> +++ b/arch/powerpc/kernel/traps.c
> @@ -765,12 +765,17 @@ void machine_check_exception(struct pt_regs *regs)
>   	if (check_io_access(regs))
>   		goto bail;
>   
> -	die("Machine check", regs, SIGBUS);
> -
>   	/* 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);
> +
> +	return;
> +
>   bail:
>   	if (!nested)
>   		nmi_exit();