From 27f6c573e0f77f7d1cc907c1494c99a61e48b7d8 Mon Sep 17 00:00:00 2001 From: "Chen, Gong" Date: Thu, 27 Mar 2014 21:24:36 -0400 Subject: [PATCH] x86, CMCI: Add proper detection of end of CMCI storms When CMCI storm persists for a long time(at least beyond predefined threshold. It's 30 seconds for now), we can watch CMCI storm is detected immediately after it subsides. ... Dec 10 22:04:29 kernel: CMCI storm detected: switching to poll mode Dec 10 22:04:59 kernel: CMCI storm subsided: switching to interrupt mode Dec 10 22:04:59 kernel: CMCI storm detected: switching to poll mode Dec 10 22:05:29 kernel: CMCI storm subsided: switching to interrupt mode ... The problem is that our logic that determines that the storm has ended is incorrect. We announce the end, re-enable interrupts and realize that the storm is still going on, so we switch back to polling mode. Rinse, repeat. When a storm happens we disable signaling of errors via CMCI and begin polling machine check banks instead. If we find any logged errors, then we need to set a per-cpu flag so that our per-cpu tests that check whether the storm is ongoing will see that errors are still being logged independently of whether mce_notify_irq() says that the error has been fully processed. cmci_clear() is not the right tool to disable a bank. It disables the interrupt for the bank as desired, but it also clears the bit for this bank in "mce_banks_owned" so we will skip the bank when polling (so we fail to see that the storm continues because we stop looking). New cmci_storm_disable_banks() just disables the interrupt while allowing polling to continue. Reported-by: William Dauchy Signed-off-by: Chen, Gong Signed-off-by: Tony Luck --- arch/x86/kernel/cpu/mcheck/mce.c | 18 +++++++++++++++++- arch/x86/kernel/cpu/mcheck/mce_intel.c | 19 ++++++++++++++++++- 2 files changed, 35 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c index 4d5419b249da..78c92125db8a 100644 --- a/arch/x86/kernel/cpu/mcheck/mce.c +++ b/arch/x86/kernel/cpu/mcheck/mce.c @@ -89,6 +89,9 @@ static DECLARE_WAIT_QUEUE_HEAD(mce_chrdev_wait); static DEFINE_PER_CPU(struct mce, mces_seen); static int cpu_missing; +/* CMCI storm detection filter */ +static DEFINE_PER_CPU(unsigned long, mce_polled_error); + /* * MCA banks polled by the period polling timer for corrected events. * With Intel CMCI, this only has MCA banks which do not support CMCI (if any). @@ -595,6 +598,7 @@ void machine_check_poll(enum mcp_flags flags, mce_banks_t *b) { struct mce m; int i; + unsigned long *v; this_cpu_inc(mce_poll_count); @@ -614,6 +618,8 @@ void machine_check_poll(enum mcp_flags flags, mce_banks_t *b) if (!(m.status & MCI_STATUS_VAL)) continue; + v = &get_cpu_var(mce_polled_error); + set_bit(0, v); /* * Uncorrected or signalled events are handled by the exception * handler when it is enabled, so don't process those here. @@ -1278,10 +1284,18 @@ static unsigned long mce_adjust_timer_default(unsigned long interval) static unsigned long (*mce_adjust_timer)(unsigned long interval) = mce_adjust_timer_default; +static int cmc_error_seen(void) +{ + unsigned long *v = &__get_cpu_var(mce_polled_error); + + return test_and_clear_bit(0, v); +} + static void mce_timer_fn(unsigned long data) { struct timer_list *t = &__get_cpu_var(mce_timer); unsigned long iv; + int notify; WARN_ON(smp_processor_id() != data); @@ -1296,7 +1310,9 @@ static void mce_timer_fn(unsigned long data) * polling interval, otherwise increase the polling interval. */ iv = __this_cpu_read(mce_next_interval); - if (mce_notify_irq()) { + notify = mce_notify_irq(); + notify |= cmc_error_seen(); + if (notify) { iv = max(iv / 2, (unsigned long) HZ/100); } else { iv = min(iv * 2, round_jiffies_relative(check_interval * HZ)); diff --git a/arch/x86/kernel/cpu/mcheck/mce_intel.c b/arch/x86/kernel/cpu/mcheck/mce_intel.c index fb6156fee6f7..3bdb95ae8c43 100644 --- a/arch/x86/kernel/cpu/mcheck/mce_intel.c +++ b/arch/x86/kernel/cpu/mcheck/mce_intel.c @@ -9,6 +9,7 @@ #include #include #include +#include #include #include #include @@ -137,6 +138,22 @@ unsigned long mce_intel_adjust_timer(unsigned long interval) } } +static void cmci_storm_disable_banks(void) +{ + unsigned long flags, *owned; + int bank; + u64 val; + + raw_spin_lock_irqsave(&cmci_discover_lock, flags); + owned = __get_cpu_var(mce_banks_owned); + for_each_set_bit(bank, owned, MAX_NR_BANKS) { + rdmsrl(MSR_IA32_MCx_CTL2(bank), val); + val &= ~MCI_CTL2_CMCI_EN; + wrmsrl(MSR_IA32_MCx_CTL2(bank), val); + } + raw_spin_unlock_irqrestore(&cmci_discover_lock, flags); +} + static bool cmci_storm_detect(void) { unsigned int cnt = __this_cpu_read(cmci_storm_cnt); @@ -158,7 +175,7 @@ static bool cmci_storm_detect(void) if (cnt <= CMCI_STORM_THRESHOLD) return false; - cmci_clear(); + cmci_storm_disable_banks(); __this_cpu_write(cmci_storm_state, CMCI_STORM_ACTIVE); r = atomic_add_return(1, &cmci_storm_on_cpus); mce_timer_kick(CMCI_POLL_INTERVAL); -- 2.20.1