[PATCH 7/7] x86/mce: Detect local MCEs properly

From: Borislav Petkov
Date: Sat Apr 30 2016 - 08:35:04 EST


From: Yazen Ghannam <Yazen.Ghannam@xxxxxxx>

Check the MCG_STATUS_LMCES bit on Intel to verify that current MCE is
local. It is always local on AMD.

Signed-off-by: Yazen Ghannam <Yazen.Ghannam@xxxxxxx>
Cc: Tony Luck <tony.luck@xxxxxxxxx>
Cc: linux-edac <linux-edac@xxxxxxxxxxxxxxx>
Cc: x86-ml <x86@xxxxxxxxxx>
Link: http://lkml.kernel.org/r/1461962923-32197-1-git-send-email-Yazen.Ghannam@xxxxxxx
[ Massage it a bit. Reflow comments. Shut up -Wmaybe-uninitialized. ]
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
---
arch/x86/kernel/cpu/mcheck/mce.c | 33 ++++++++++++++++++++-------------
1 file changed, 20 insertions(+), 13 deletions(-)

diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c
index c356f47894c9..aeda44684758 100644
--- a/arch/x86/kernel/cpu/mcheck/mce.c
+++ b/arch/x86/kernel/cpu/mcheck/mce.c
@@ -1038,11 +1038,12 @@ void do_machine_check(struct pt_regs *regs, long error_code)
int i;
int worst = 0;
int severity;
+
/*
* Establish sequential order between the CPUs entering the machine
* check handler.
*/
- int order;
+ int order = -1;
/*
* If no_way_out gets set, there is no safe way to recover from this
* MCE. If mca_cfg.tolerant is cranked up, we'll try anyway.
@@ -1056,7 +1057,12 @@ void do_machine_check(struct pt_regs *regs, long error_code)
DECLARE_BITMAP(toclear, MAX_NR_BANKS);
DECLARE_BITMAP(valid_banks, MAX_NR_BANKS);
char *msg = "Unknown";
- int lmce = 0;
+
+ /*
+ * MCEs are always local on AMD. Same is determined by MCG_STATUS_LMCES
+ * on Intel.
+ */
+ int lmce = 1;

/* If this CPU is offline, just bail out. */
if (cpu_is_offline(smp_processor_id())) {
@@ -1095,19 +1101,20 @@ void do_machine_check(struct pt_regs *regs, long error_code)
kill_it = 1;

/*
- * Check if this MCE is signaled to only this logical processor
+ * Check if this MCE is signaled to only this logical processor,
+ * on Intel only.
*/
- if (m.mcgstatus & MCG_STATUS_LMCES)
- lmce = 1;
- else {
- /*
- * Go through all the banks in exclusion of the other CPUs.
- * This way we don't report duplicated events on shared banks
- * because the first one to see it will clear it.
- * If this is a Local MCE, then no need to perform rendezvous.
- */
+ if (m.cpuvendor == X86_VENDOR_INTEL)
+ lmce = m.mcgstatus & MCG_STATUS_LMCES;
+
+ /*
+ * Go through all banks in exclusion of the other CPUs. This way we
+ * don't report duplicated events on shared banks because the first one
+ * to see it will clear it. If this is a Local MCE, then no need to
+ * perform rendezvous.
+ */
+ if (!lmce)
order = mce_start(&no_way_out);
- }

for (i = 0; i < cfg->banks; i++) {
__clear_bit(i, toclear);
--
2.7.3