x86 EDAC, sb_edac.c: Take account of channel hashing when needed

commit ea5dfb5f upstream.

Haswell and Broadwell can be configured to hash the channel
interleave function using bits [27:12] of the physical address.

On those processor models we must check to see if hashing is
enabled (bit21 of the HASWELL_HASYSDEFEATURE2 register) and
act accordingly.

Based on a patch by patrickg <patrickg@supermicro.com>
Tested-by: Patrick Geary <patrickg@supermicro.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Acked-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Cc: Aristeu Rozanski <arozansk@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-edac@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>

drivers/edac/sb_edac.c

@@ -322,6 +322,7 @@ struct sbridge_pvt {
 
 	/* Memory type detection */
 	bool			is_mirrored, is_lockstep, is_close_pg;
+	bool			is_chan_hash;
 
 	/* Fifo double buffers */
 	struct mce		mce_entry[MCE_LOG_LEN];
@@ -782,6 +783,20 @@ static inline u8 sad_pkg_ha(u8 pkg)
 	return (pkg >> 2) & 0x1;
 }
 
+static int haswell_chan_hash(int idx, u64 addr)
+{
+	int i;
+
+	/*
+	 * XOR even bits from 12:26 to bit0 of idx,
+	 *     odd bits from 13:27 to bit1
+	 */
+	for (i = 12; i < 28; i += 2)
+		idx ^= (addr >> i) & 3;
+
+	return idx;
+}
+
 /****************************************************************************
 			Memory check routines
  ****************************************************************************/
@@ -853,6 +868,10 @@ static int get_dimm_config(struct mem_ctl_info *mci)
 	enum edac_type mode;
 	enum mem_type mtype;
 
+	if (pvt->info.type == HASWELL || pvt->info.type == BROADWELL) {
+		pci_read_config_dword(pvt->pci_ha0, HASWELL_HASYSDEFEATURE2, &reg);
+		pvt->is_chan_hash = GET_BITFIELD(reg, 21, 21);
+	}
 	if (pvt->info.type == HASWELL || pvt->info.type == BROADWELL)
 		pci_read_config_dword(pvt->pci_sad1, SAD_TARGET, &reg);
 	else
@@ -1320,8 +1339,11 @@ static int get_memory_error_data(struct mem_ctl_info *mci,
 
 	if (ch_way == 3)
 		idx = addr >> 6;
-	else
+	else {
 		idx = (addr >> (6 + sck_way + shiftup)) & 0x3;
+		if (pvt->is_chan_hash)
+			idx = haswell_chan_hash(idx, addr);
+	}
 	idx = idx % ch_way;
 
 	/*