powerpc/64s: Report SLB multi-hit rather than parity error

When we take an SLB multi-hit on bare metal, we see both the multi-hit
and parity error bits set in DSISR. The user manuals indicates this is
expected to always happen on Power8, whereas on Power9 it says a
multi-hit will "usually" also cause a parity error.

We decide what to do based on the various error tables in mce_power.c,
and because we process them in order and only report the first, we
currently always report a parity error but not the multi-hit, eg:

  Severe Machine check interrupt [Recovered]
    Initiator: CPU
    Error type: SLB [Parity]
      Effective address: c000000ffffd4300

Although this is correct, it leaves the user wondering why they got a
parity error. It would be clearer instead if we reported the
multi-hit because that is more likely to be simply a software bug,
whereas a true parity error is possibly an indication of a bad core.

We can do that simply by reordering the error tables so that multi-hit
appears before parity. That doesn't affect the error recovery at all,
because we flush the SLB either way.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/kernel/mce_power.c

@@ -257,12 +257,12 @@ static const struct mce_derror_table mce_p7_derror_table[] = {
 { 0x00000400, true,
   MCE_ERROR_TYPE_TLB,  MCE_TLB_ERROR_MULTIHIT,
   MCE_INITIATOR_CPU,   MCE_SEV_ERROR_SYNC, },
+{ 0x00000080, true,
+  MCE_ERROR_TYPE_SLB,  MCE_SLB_ERROR_MULTIHIT,	/* Before PARITY */
+  MCE_INITIATOR_CPU,   MCE_SEV_ERROR_SYNC, },
 { 0x00000100, true,
   MCE_ERROR_TYPE_SLB,  MCE_SLB_ERROR_PARITY,
   MCE_INITIATOR_CPU,   MCE_SEV_ERROR_SYNC, },
-{ 0x00000080, true,
-  MCE_ERROR_TYPE_SLB,  MCE_SLB_ERROR_MULTIHIT,
-  MCE_INITIATOR_CPU,   MCE_SEV_ERROR_SYNC, },
 { 0x00000040, true,
   MCE_ERROR_TYPE_SLB,  MCE_SLB_ERROR_INDETERMINATE, /* BOTH */
   MCE_INITIATOR_CPU,   MCE_SEV_ERROR_SYNC, },
@@ -290,12 +290,12 @@ static const struct mce_derror_table mce_p8_derror_table[] = {
 { 0x00000200, true,
   MCE_ERROR_TYPE_ERAT, MCE_ERAT_ERROR_MULTIHIT, /* SECONDARY ERAT */
   MCE_INITIATOR_CPU,   MCE_SEV_ERROR_SYNC, },
+{ 0x00000080, true,
+  MCE_ERROR_TYPE_SLB,  MCE_SLB_ERROR_MULTIHIT,	/* Before PARITY */
+  MCE_INITIATOR_CPU,   MCE_SEV_ERROR_SYNC, },
 { 0x00000100, true,
   MCE_ERROR_TYPE_SLB,  MCE_SLB_ERROR_PARITY,
   MCE_INITIATOR_CPU,   MCE_SEV_ERROR_SYNC, },
-{ 0x00000080, true,
-  MCE_ERROR_TYPE_SLB,  MCE_SLB_ERROR_MULTIHIT,
-  MCE_INITIATOR_CPU,   MCE_SEV_ERROR_SYNC, },
 { 0, false, 0, 0, 0, 0 } };
 
 static const struct mce_derror_table mce_p9_derror_table[] = {
@@ -320,12 +320,12 @@ static const struct mce_derror_table mce_p9_derror_table[] = {
 { 0x00000200, false,
   MCE_ERROR_TYPE_USER, MCE_USER_ERROR_TLBIE,
   MCE_INITIATOR_CPU,   MCE_SEV_ERROR_SYNC, },
+{ 0x00000080, true,
+  MCE_ERROR_TYPE_SLB,  MCE_SLB_ERROR_MULTIHIT,	/* Before PARITY */
+  MCE_INITIATOR_CPU,   MCE_SEV_ERROR_SYNC, },
 { 0x00000100, true,
   MCE_ERROR_TYPE_SLB,  MCE_SLB_ERROR_PARITY,
   MCE_INITIATOR_CPU,   MCE_SEV_ERROR_SYNC, },
-{ 0x00000080, true,
-  MCE_ERROR_TYPE_SLB,  MCE_SLB_ERROR_MULTIHIT,
-  MCE_INITIATOR_CPU,   MCE_SEV_ERROR_SYNC, },
 { 0x00000040, true,
   MCE_ERROR_TYPE_RA,   MCE_RA_ERROR_LOAD,
   MCE_INITIATOR_CPU,   MCE_SEV_ERROR_SYNC, },