linux-kernel - [PATCH] sb_edac: Enable channel interleave hashing support for HSX/BDX

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Date:	Tue, 29 Mar 2016 14:30:27 -0700
From:	patrickg <patrickg@...ermicro.com>
To:	<linux-kernel@...r.kernel.org>
CC:	<mchehab@...hat.com>, <jim.m.snow@...el.com>
Subject: [PATCH] sb_edac: Enable channel interleave hashing support for
 HSX/BDX

Patch implements channel interleave hash if MCChanHashEn is set in HA on 
Haswell/Broadwell.  If this bit was set, but no math was used to 
calculate the correct interleave index, sb_edac would place errors on 
incorrect channels.

diff --git a/drivers/edac/sb_edac.c b/drivers/edac/sb_edac.c
index 93f0d41..02f6fd6 100644
--- a/drivers/edac/sb_edac.c
+++ b/drivers/edac/sb_edac.c
@@ -361,7 +361,7 @@ struct sbridge_pvt {
         struct sbridge_channel  channel[NUM_CHANNELS];

         /* Memory type detection */
-       bool                    is_mirrored, is_lockstep, is_close_pg;
+       bool                    is_mirrored, is_lockstep, is_close_pg, 
is_ch_hash;

         /* Fifo double buffers */
         struct mce              mce_entry[MCE_LOG_LEN];
@@ -1060,6 +1060,16 @@ static inline u8 sad_pkg_ha(u8 pkg)
         return (pkg >> 2) & 0x1;
  }

+/* Hash bits 12 through 27 against the two interleave bits */
+static u32 haswell_chan_hash(u32 interleave, u64 addr) {
+               u8 i=0, bits=0;
+               for (i=12; i<28; i+=2) {
+                       bits = (addr >> i) & 0x3;
+                       interleave ^= bits;
+               }
+               return interleave;
+}
+
  /****************************************************************************
                         Memory check routines
****************************************************************************/
@@ -1616,6 +1626,13 @@ static int get_dimm_config(struct mem_ctl_info *mci)
                 KNL_MAX_CHANNELS : NUM_CHANNELS;
         u64 knl_mc_sizes[KNL_MAX_CHANNELS];

+       /* On HSX/BDX, check channel hash bit. */
+       pvt->is_ch_hash = 0;
+       if (pvt->info.type == HASWELL || pvt->info.type == BROADWELL) {
+               pci_read_config_dword(pvt->pci_ha0, 
HASWELL_HASYSDEFEATURE2, &reg);
+               pvt->is_ch_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);
@@ -2120,10 +2137,13 @@ static int get_memory_error_data(struct 
mem_ctl_info *mci,
         ch_way = TAD_CH(reg) + 1;
         sck_way = 1 << TAD_SOCK(reg);

-       if (ch_way == 3)
+       if (ch_way == 3) {
                 idx = addr >> 6;
-       else
+       } else {
                 idx = (addr >> (6 + sck_way + shiftup)) & 0x3;
+               if (pvt->is_ch_hash)
+                       idx = haswell_chan_hash(idx, addr);
+       }
         idx = idx % ch_way;

         /*