commit ea5dfb5fae81939f777ca569d8cfb599252da2e8
author Tony Luck <tony.luck@intel.com> Thu Apr 14 10:22:02 2016 -0700
committer Ingo Molnar <mingo@kernel.org> Fri Apr 22 10:10:01 2016 +0200
tree ad877f65ffb0a4090d17a78069212c8d75662730
parent ff15e95c82768d589957dbb17d7eb7dba7904659

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

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
Cc: stable@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

drivers/edac/sb_edac.c

diff --git a/drivers/edac/sb_edac.c b/drivers/edac/sb_edac.c
index f4666b0..468447a 100644
--- a/drivers/edac/sb_edac.c
+++ b/drivers/edac/sb_edac.c
@@ -362,6 +362,7 @@
 
 	/* 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];
@@ -1060,6 +1061,20 @@
 	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
  ****************************************************************************/
@@ -1616,6 +1631,10 @@
 		KNL_MAX_CHANNELS : NUM_CHANNELS;
 	u64 knl_mc_sizes[KNL_MAX_CHANNELS];
 
+	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 ||
 			pvt->info.type == KNIGHTS_LANDING)
 		pci_read_config_dword(pvt->pci_sad1, SAD_TARGET, &reg);
@@ -2122,8 +2141,11 @@
 
 	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;
 
 	/*