powerpc/traps: fix recoverability of machine check handling on book3s/32

commit 0bbea75 upstream.

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: b96672d ("powerpc: Machine check interrupt is a non-maskable interrupt")
Fixes: daf00ae ("powerpc/traps: restore recoverability of machine_check interrupts")
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: stable@vger.kernel.org
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

arch/powerpc/kernel/traps.c

@@ -694,15 +694,15 @@ 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: