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Subject[tip:ras/urgent] x86/mce/AMD: Give a name to MCA bank 3 when accessed with legacy MSRs
Commit-ID:  7cc5ad0d4aec505bee7f49696867668aa3889195
Gitweb: http://git.kernel.org/tip/7cc5ad0d4aec505bee7f49696867668aa3889195
Author: Yazen Ghannam <yazen.ghannam@amd.com>
AuthorDate: Thu, 30 Mar 2017 13:17:14 +0200
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Fri, 31 Mar 2017 08:10:09 +0200

x86/mce/AMD: Give a name to MCA bank 3 when accessed with legacy MSRs

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:

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()
kobject_add()
kobject_create_and_add()
threshold_create_device()
threshold_init_device()
do_one_initcall()
kernel_init_freeable()
kernel_init()
ret_from_fork()

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.

Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: <stable@vger.kernel.org> # 3.10..
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-edac <linux-edac@vger.kernel.org>
Link: http://lkml.kernel.org/r/20170330111713.cnkbloffyouxg52e@pd.tnic
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
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 524cc57..6e4a047 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",
};
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