linux-kernel - [PATCH 3.12 58/86] x86/mce/AMD: Give a name to MCA bank 3 when accessed with legacy MSRs

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Message-Id: <fb49d2c0746cc25bb86dfca7c29b475eb6eae4e2.1493888632.git.jslaby@suse.cz>
Date:   Thu,  4 May 2017 11:04:23 +0200
From:   Jiri Slaby <jslaby@...e.cz>
To:     stable@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org,
        Yazen Ghannam <yazen.ghannam@....com>,
        Borislav Petkov <bp@...e.de>,
        Thomas Gleixner <tglx@...utronix.de>,
        Jiri Slaby <jslaby@...e.cz>
Subject: [PATCH 3.12 58/86] x86/mce/AMD: Give a name to MCA bank 3 when accessed with legacy MSRs

From: Yazen Ghannam <yazen.ghannam@....com>

3.12-stable review patch.  If anyone has any objections, please let me know.

===============

commit 29f72ce3e4d18066ec75c79c857bee0618a3504b upstream.

MCA bank 3 is reserved on systems pre-Fam17h, so it didn't have a name.
However, MCA bank 3 is defined on Fam17h systems and can be accessed
using legacy MSRs. Without a name we get a stack trace on Fam17h systems
when trying to register sysfs files for bank 3 on kernels that don't
recognize Scalable MCA.

Call MCA bank 3 "decode_unit" since this is what it represents on
Fam17h. This will allow kernels without SMCA support to see this bank on
Fam17h+ and prevent the stack trace. This will not affect older systems
since this bank is reserved on them, i.e. it'll be ignored.

Tested on AMD Fam15h and Fam17h systems.

  WARNING: CPU: 26 PID: 1 at lib/kobject.c:210 kobject_add_internal
  kobject: (ffff88085bb256c0): attempted to be registered with empty name!
  ...
  Call Trace:
   kobject_add_internal
   kobject_add
   kobject_create_and_add
   threshold_create_device
   threshold_init_device

Signed-off-by: Yazen Ghannam <yazen.ghannam@....com>
Signed-off-by: Borislav Petkov <bp@...e.de>
Link: http://lkml.kernel.org/r/1490102285-3659-1-git-send-email-Yazen.Ghannam@amd.com
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Signed-off-by: Jiri Slaby <jslaby@...e.cz>
---
 arch/x86/kernel/cpu/mcheck/mce_amd.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/mcheck/mce_amd.c b/arch/x86/kernel/cpu/mcheck/mce_amd.c
index 603df4f74640..0c05ab602815 100644
--- a/arch/x86/kernel/cpu/mcheck/mce_amd.c
+++ b/arch/x86/kernel/cpu/mcheck/mce_amd.c
@@ -51,7 +51,7 @@ static const char * const th_names[] = {
 	"load_store",
 	"insn_fetch",
 	"combined_unit",
-	"",
+	"decode_unit",
 	"northbridge",
 	"execution_unit",
 };
-- 
2.12.2