[RESEND PATCH v2] powerpc/mce: Fix SLB rebolting during MCE recovery path.

[Mahesh J Salgaonkar]

From: Mahesh Salgaonkar <mahesh at linux.vnet.ibm.com>

With the powerpc next commit e7e81847478 (powerpc/mce: Fix SLB rebolting
during MCE recovery path.), the SLB error recovery is broken. The new
change now does not add index value to RB[52-63] that selects the SLB
entry while rebolting, instead it assumes that the shadow save area
already have index embeded correctly in esid field. While all valid bolted
save areas do contain index value set correctly, there is a case where
3rd (KSTACK_INDEX) entry for kernel stack does not embed index for NULL
esid entry. This patch fixes that.

Without this patch the SLB rebolt code overwrites the 1st entry of kernel
linear mapping and causes SLB recovery to fail.

Signed-off-by: Mahesh Salgaonkar <mahesh at linux.vnet.ibm.com>
Signed-off-by: Nicholas Piggin <npiggin at gmail.com>
Reviewed-by: Nicholas Piggin <npiggin at gmail.com>
---
 arch/powerpc/mm/slb.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/mm/slb.c b/arch/powerpc/mm/slb.c
index 0b095fa54049..9f574e59d178 100644
--- a/arch/powerpc/mm/slb.c
+++ b/arch/powerpc/mm/slb.c
@@ -70,7 +70,7 @@ static inline void slb_shadow_update(unsigned long ea, int ssize,
 
 static inline void slb_shadow_clear(enum slb_index index)
 {
-	WRITE_ONCE(get_slb_shadow()->save_area[index].esid, 0);
+	WRITE_ONCE(get_slb_shadow()->save_area[index].esid, cpu_to_be64(index));
 }
 
 static inline void create_shadowed_slbe(unsigned long ea, int ssize,