From c7f6fa44115d401e89db730f357629d39f8e4ba6 Mon Sep 17 00:00:00 2001 From: Bartlomiej Zolnierkiewicz Date: Tue, 28 Jul 2009 23:52:54 +0200 Subject: x86, mce: don't log boot MCEs on Pentium M (model == 13) CPUs On my legacy Pentium M laptop (Acer Extensa 2900) I get bogus MCE on a cold boot with CONFIG_X86_NEW_MCE enabled, i.e. (after decoding it with mcelog): MCE 0 HARDWARE ERROR. This is *NOT* a software problem! Please contact your hardware vendor CPU 0 BANK 1 MCG status: MCi status: Error overflow Uncorrected error Error enabled Processor context corrupt MCA: Data CACHE Level-1 UNKNOWN Error STATUS f200000000000195 MCGSTATUS 0 [ The other STATUS values observed: f2000000000001b5 (... UNKNOWN error) and f200000000000115 (... READ Error). To verify that this is not a CONFIG_X86_NEW_MCE bug I also modified the CONFIG_X86_OLD_MCE code (which doesn't log any MCEs) to dump content of STATUS MSR before it is cleared during initialization. ] Since the bogus MCE results in a kernel taint (which in turn disables lockdep support) don't log boot MCEs on Pentium M (model == 13) CPUs by default ("mce=bootlog" boot parameter can be be used to get the old behavior). Signed-off-by: Bartlomiej Zolnierkiewicz Reviewed-by: Andi Kleen Signed-off-by: H. Peter Anvin Signed-off-by: Ingo Molnar --- arch/x86/kernel/cpu/mcheck/mce.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'arch/x86/kernel/cpu/mcheck/mce.c') diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c index 1cfb623ce11..a0c2910d96a 100644 --- a/arch/x86/kernel/cpu/mcheck/mce.c +++ b/arch/x86/kernel/cpu/mcheck/mce.c @@ -1273,6 +1273,10 @@ static void mce_cpu_quirks(struct cpuinfo_x86 *c) if ((c->x86 > 6 || (c->x86 == 6 && c->x86_model >= 0xe)) && monarch_timeout < 0) monarch_timeout = USEC_PER_SEC; + + /* There are also broken BIOSes on some Pentium M systems. */ + if (c->x86 == 6 && c->x86_model == 13 && mce_bootlog < 0) + mce_bootlog = 0; } if (monarch_timeout < 0) monarch_timeout = 0; -- cgit v1.2.3 From e412cd257e0d51e0ecbb89f50953835b5a0681b2 Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Mon, 17 Aug 2009 10:19:00 +0200 Subject: x86, mce: Don't initialize MCEs on unknown CPUs An older test-box started hanging at the following point during bootup: [ 0.022996] Mount-cache hash table entries: 512 [ 0.024996] Initializing cgroup subsys debug [ 0.025996] Initializing cgroup subsys cpuacct [ 0.026995] Initializing cgroup subsys devices [ 0.027995] Initializing cgroup subsys freezer [ 0.028995] mce: CPU supports 5 MCE banks I've bisected it down to commit 4efc0670 ("x86, mce: use 64bit machine check code on 32bit"), which utilizes the MCE code on 32-bit systems too. The problem is caused by this detail in my config: # CONFIG_CPU_SUP_INTEL is not set This disables the quirks in mce_cpu_quirks() but still enables MCE support - which then hangs due to the missing quirk workaround needed on this CPU: if (c->x86 == 6 && c->x86_model < 0x1A && banks > 0) mce_banks[0].init = 0; The safe solution is to not initialize MCEs if we dont know on what CPU we are running (or if that CPU's support code got disabled in the config). Also be a bit more defensive on 32-bit systems: dont do a boot-time dump of pending MCEs not just on the specific system that we found a problem with (Pentium-M), but earlier ones as well. Now this problem is probably not common and disabling CPU support is rare - but still being more defensive in something we turned on for a wide range of CPUs is prudent. Cc: Hidetoshi Seto LKML-Reference: Message-ID: <4A88E3E4.40506@jp.fujitsu.com> Signed-off-by: Ingo Molnar --- arch/x86/kernel/cpu/mcheck/mce.c | 19 ++++++++++++++----- 1 file changed, 14 insertions(+), 5 deletions(-) (limited to 'arch/x86/kernel/cpu/mcheck/mce.c') diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c index a0c2910d96a..01213048f62 100644 --- a/arch/x86/kernel/cpu/mcheck/mce.c +++ b/arch/x86/kernel/cpu/mcheck/mce.c @@ -1226,8 +1226,13 @@ static void mce_init(void) } /* Add per CPU specific workarounds here */ -static void mce_cpu_quirks(struct cpuinfo_x86 *c) +static int mce_cpu_quirks(struct cpuinfo_x86 *c) { + if (c->x86_vendor == X86_VENDOR_UNKNOWN) { + pr_info("MCE: unknown CPU type - not enabling MCE support.\n"); + return -EOPNOTSUPP; + } + /* This should be disabled by the BIOS, but isn't always */ if (c->x86_vendor == X86_VENDOR_AMD) { if (c->x86 == 15 && banks > 4) { @@ -1274,14 +1279,19 @@ static void mce_cpu_quirks(struct cpuinfo_x86 *c) monarch_timeout < 0) monarch_timeout = USEC_PER_SEC; - /* There are also broken BIOSes on some Pentium M systems. */ - if (c->x86 == 6 && c->x86_model == 13 && mce_bootlog < 0) + /* + * There are also broken BIOSes on some Pentium M and + * earlier systems: + */ + if (c->x86 == 6 && c->x86_model <= 13 && mce_bootlog < 0) mce_bootlog = 0; } if (monarch_timeout < 0) monarch_timeout = 0; if (mce_bootlog != 0) mce_panic_timeout = 30; + + return 0; } static void __cpuinit mce_ancient_init(struct cpuinfo_x86 *c) @@ -1342,11 +1352,10 @@ void __cpuinit mcheck_init(struct cpuinfo_x86 *c) if (!mce_available(c)) return; - if (mce_cap_init() < 0) { + if (mce_cap_init() < 0 || mce_cpu_quirks(c) < 0) { mce_disabled = 1; return; } - mce_cpu_quirks(c); machine_check_vector = do_machine_check; -- cgit v1.2.3