From 680b6cfd3cee30a7d997d49430fb73af84523853 Mon Sep 17 00:00:00 2001 From: Hidetoshi Seto Date: Wed, 26 Aug 2009 16:20:36 +0900 Subject: [PATCH] x86, mce: CE in last bank prevents panic by unknown MCE If MCE handler is called but none of mces_seen have machine check event which might signal the MCE (i.e. event higher than MCE_KEEP_SEVERITY), panic with "Machine check from unknown source" will be taken since the MCE is assumed to be signaled from external agent or so. Usually mces_seen never point MCE_KEEP_SEVERITY event such as CE. But it can happen because initial value of mces_seen is accidentally modified by mce_no_way_out() - in case if mce_no_way_out() run through all banks and the last bank has the CE, mces_seen points the CE and the "panic by unknown" will not be taken. This patch fixes this undesired behavior, and clarifies the logic. Signed-off-by: Hidetoshi Seto Cc: H. Peter Anvin Cc: Andi Kleen Cc: Jin Dongming LKML-Reference: <4A94E244.3020301@jp.fujitsu.com> Signed-off-by: Ingo Molnar Reported-by: Jin Dongming --- arch/x86/kernel/cpu/mcheck/mce.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c index 54bd1b2fb4c..325559d1aa5 100644 --- a/arch/x86/kernel/cpu/mcheck/mce.c +++ b/arch/x86/kernel/cpu/mcheck/mce.c @@ -612,7 +612,7 @@ out: * This way we prevent any potential data corruption in a unrecoverable case * and also makes sure always all CPU's errors are examined. * - * Also this detects the case of an machine check event coming from outer + * Also this detects the case of a machine check event coming from outer * space (not detected by any CPUs) In this case some external agent wants * us to shut down, so panic too. * @@ -665,7 +665,7 @@ static void mce_reign(void) * No machine check event found. Must be some external * source or one CPU is hung. Panic. */ - if (!m && tolerant < 3) + if (global_worst <= MCE_KEEP_SEVERITY && tolerant < 3) mce_panic("Machine check from unknown source", NULL, NULL); /* @@ -889,11 +889,11 @@ void do_machine_check(struct pt_regs *regs, long error_code) mce_setup(&m); m.mcgstatus = mce_rdmsrl(MSR_IA32_MCG_STATUS); - no_way_out = mce_no_way_out(&m, &msg); - final = &__get_cpu_var(mces_seen); *final = m; + no_way_out = mce_no_way_out(&m, &msg); + barrier(); /* -- 2.11.4.GIT