powerpc/fsl-booke: Handle L1 D-cache parity error correctly on e500mc

If the L1 D-Cache is in write shadow mode the HW will auto-recover the
error.  However we might still log the error and cause a machine check
(if L1CSR0[CPE] - Cache error checking enable).  We should only treat
the non-write shadow case as non-recoverable.

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index f19d977..4e59082 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -457,7 +457,14 @@
 
 	if (reason & MCSR_DCPERR_MC) {
 		printk("Data Cache Parity Error\n");
-		recoverable = 0;
+
+		/*
+		 * In write shadow mode we auto-recover from the error, but it
+		 * may still get logged and cause a machine check.  We should
+		 * only treat the non-write shadow case as non-recoverable.
+		 */
+		if (!(mfspr(SPRN_L1CSR2) & L1CSR2_DCWS))
+			recoverable = 0;
 	}
 
 	if (reason & MCSR_L2MMU_MHIT) {