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

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Message-ID: <20170330111713.cnkbloffyouxg52e@pd.tnic>
Date:   Thu, 30 Mar 2017 13:17:14 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     x86-ml <x86@...nel.org>
Cc:     lkml <linux-kernel@...r.kernel.org>
Subject: [PATCH] x86/mce/AMD: Give a name to MCA bank 3 when accessed with
 legacy MSRs

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

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:
   dump_stack
   warn_slowpath_common
   warn_slowpath_fmt
   ? kobject_add_internal
   ? kfree_const
   kobject_add_internal
   ? kfree_const
   kobject_add
   kobject_create_and_add
   threshold_create_device
   ? mcheck_vendor_init_severity
   threshold_init_device
   do_one_initcall
   kernel_init_freeable
   ? rest_init
   kernel_init
   ret_from_fork
   ? rest_init

Signed-off-by: Yazen Ghannam <yazen.ghannam@....com>
Cc: <stable@...r.kernel.org> # 3.10..
Cc: linux-edac <linux-edac@...r.kernel.org>
Cc: x86-ml <x86@...nel.org>
Link: http://lkml.kernel.org/r/1490102285-3659-1-git-send-email-Yazen.Ghannam@amd.com
Signed-off-by: Borislav Petkov <bp@...e.de>
---

To tip/ras/urgent pls.

 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 524cc5780a77..6e4a047e4b68 100644
--- a/arch/x86/kernel/cpu/mcheck/mce_amd.c
+++ b/arch/x86/kernel/cpu/mcheck/mce_amd.c
@@ -60,7 +60,7 @@ static const char * const th_names[] = {
 	"load_store",
 	"insn_fetch",
 	"combined_unit",
-	"",
+	"decode_unit",
 	"northbridge",
 	"execution_unit",
 };
-- 
2.11.0

-- 
Regards/Gruss,
    Boris.

Good mailing practices for 400: avoid top-posting and trim the reply.