Merge commit '5bc66170dc486556a1e36fd384463536573f4b82' into x86/urgent

From Borislav Petkov <bp@amd64.org>:

Below is a RAS fix which reverts the addition of a sysfs attribute
which we agreed is not needed, post-factum. And this should go in now
because that sysfs attribute is going to end up in 3.7 otherwise and
thus exposed to userspace; removing it then would be a lot harder.

This is done as a merge rather than a simple patch/cherry-pick since
the baseline for this patch was not in the previous x86/urgent.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

4 files changed, 228 insertions, 48 deletions

diff --git a/arch/x86/kernel/cpu/mcheck/mce-inject.c b/arch/x86/kernel/cpu/mcheck/mce-inject.c
index fc4beb39357..ddc72f83933 100644
--- a/arch/x86/kernel/cpu/mcheck/mce-inject.c
+++ b/arch/x86/kernel/cpu/mcheck/mce-inject.c
@@ -78,6 +78,7 @@ static void raise_exception(struct mce *m, struct pt_regs *pregs)
 }
 
 static cpumask_var_t mce_inject_cpumask;
+static DEFINE_MUTEX(mce_inject_mutex);
 
 static int mce_raise_notify(unsigned int cmd, struct pt_regs *regs)
 {
@@ -194,7 +195,11 @@ static void raise_mce(struct mce *m)
                 put_online_cpus();
         } else
 #endif
+        {
+                preempt_disable();
                 raise_local();
+                preempt_enable();
+        }
 }
 
 /* Error injection interface */
@@ -225,7 +230,10 @@ static ssize_t mce_write(struct file *filp, const char __user *ubuf,
          * so do it a jiffie or two later everywhere.
          */
         schedule_timeout(2);
+
+        mutex_lock(&mce_inject_mutex);
         raise_mce(&m);
+        mutex_unlock(&mce_inject_mutex);
         return usize;
 }
 
diff --git a/arch/x86/kernel/cpu/mcheck/mce-internal.h b/arch/x86/kernel/cpu/mcheck/mce-internal.h
index ed44c8a6585..6a05c1d327a 100644
--- a/arch/x86/kernel/cpu/mcheck/mce-internal.h
+++ b/arch/x86/kernel/cpu/mcheck/mce-internal.h
@@ -28,6 +28,18 @@ extern int mce_ser;
 
 extern struct mce_bank *mce_banks;
 
+#ifdef CONFIG_X86_MCE_INTEL
+unsigned long mce_intel_adjust_timer(unsigned long interval);
+void mce_intel_cmci_poll(void);
+void mce_intel_hcpu_update(unsigned long cpu);
+#else
+# define mce_intel_adjust_timer mce_adjust_timer_default
+static inline void mce_intel_cmci_poll(void) { }
+static inline void mce_intel_hcpu_update(unsigned long cpu) { }
+#endif
+
+void mce_timer_kick(unsigned long interval);
+
 #ifdef CONFIG_ACPI_APEI
 int apei_write_mce(struct mce *m);
 ssize_t apei_read_mce(struct mce *m, u64 *record_id);
diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c
index 292d0258311..46cbf868969 100644
--- a/arch/x86/kernel/cpu/mcheck/mce.c
+++ b/arch/x86/kernel/cpu/mcheck/mce.c
@@ -83,6 +83,7 @@ static int			mce_dont_log_ce		__read_mostly;
 int                             mce_cmci_disabled       __read_mostly;
 int                             mce_ignore_ce           __read_mostly;
 int                             mce_ser                 __read_mostly;
+int                             mce_bios_cmci_threshold __read_mostly;
 
 struct mce_bank                *mce_banks               __read_mostly;
 
@@ -1266,6 +1267,14 @@ static unsigned long check_interval = 5 * 60; /* 5 minutes */
 static DEFINE_PER_CPU(unsigned long, mce_next_interval); /* in jiffies */
 static DEFINE_PER_CPU(struct timer_list, mce_timer);
 
+static unsigned long mce_adjust_timer_default(unsigned long interval)
+{
+        return interval;
+}
+
+static unsigned long (*mce_adjust_timer)(unsigned long interval) =
+        mce_adjust_timer_default;
+
 static void mce_timer_fn(unsigned long data)
 {
         struct timer_list *t = &__get_cpu_var(mce_timer);
@@ -1276,6 +1285,7 @@ static void mce_timer_fn(unsigned long data)
         if (mce_available(__this_cpu_ptr(&cpu_info))) {
                 machine_check_poll(MCP_TIMESTAMP,
                                 &__get_cpu_var(mce_poll_banks));
+                mce_intel_cmci_poll();
         }
 
         /*
@@ -1283,14 +1293,38 @@ 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())
+        if (mce_notify_irq()) {
                 iv = max(iv / 2, (unsigned long) HZ/100);
-        else
+        } else {
                 iv = min(iv * 2, round_jiffies_relative(check_interval * HZ));
+                iv = mce_adjust_timer(iv);
+        }
         __this_cpu_write(mce_next_interval, iv);
+        /* Might have become 0 after CMCI storm subsided */
+        if (iv) {
+                t->expires = jiffies + iv;
+                add_timer_on(t, smp_processor_id());
+        }
+}
 
-        t->expires = jiffies + iv;
-        add_timer_on(t, smp_processor_id());
+/*
+ * Ensure that the timer is firing in @interval from now.
+ */
+void mce_timer_kick(unsigned long interval)
+{
+        struct timer_list *t = &__get_cpu_var(mce_timer);
+        unsigned long when = jiffies + interval;
+        unsigned long iv = __this_cpu_read(mce_next_interval);
+
+        if (timer_pending(t)) {
+                if (time_before(when, t->expires))
+                        mod_timer_pinned(t, when);
+        } else {
+                t->expires = round_jiffies(when);
+                add_timer_on(t, smp_processor_id());
+        }
+        if (interval < iv)
+                __this_cpu_write(mce_next_interval, interval);
 }
 
 /* Must not be called in IRQ context where del_timer_sync() can deadlock */
@@ -1585,6 +1619,7 @@ static void __mcheck_cpu_init_vendor(struct cpuinfo_x86 *c)
         switch (c->x86_vendor) {
         case X86_VENDOR_INTEL:
                 mce_intel_feature_init(c);
+                mce_adjust_timer = mce_intel_adjust_timer;
                 break;
         case X86_VENDOR_AMD:
                 mce_amd_feature_init(c);
@@ -1594,23 +1629,28 @@ static void __mcheck_cpu_init_vendor(struct cpuinfo_x86 *c)
         }
 }
 
-static void __mcheck_cpu_init_timer(void)
+static void mce_start_timer(unsigned int cpu, struct timer_list *t)
 {
-        struct timer_list *t = &__get_cpu_var(mce_timer);
-        unsigned long iv = check_interval * HZ;
+        unsigned long iv = mce_adjust_timer(check_interval * HZ);
 
-        setup_timer(t, mce_timer_fn, smp_processor_id());
+        __this_cpu_write(mce_next_interval, iv);
 
-        if (mce_ignore_ce)
+        if (mce_ignore_ce || !iv)
                 return;
 
-        __this_cpu_write(mce_next_interval, iv);
-        if (!iv)
-                return;
         t->expires = round_jiffies(jiffies + iv);
         add_timer_on(t, smp_processor_id());
 }
 
+static void __mcheck_cpu_init_timer(void)
+{
+        struct timer_list *t = &__get_cpu_var(mce_timer);
+        unsigned int cpu = smp_processor_id();
+
+        setup_timer(t, mce_timer_fn, cpu);
+        mce_start_timer(cpu, t);
+}
+
 /* Handle unconfigured int18 (should never happen) */
 static void unexpected_machine_check(struct pt_regs *regs, long error_code)
 {
@@ -1907,6 +1947,7 @@ static struct miscdevice mce_chrdev_device = {
  *      check, or 0 to not wait
  * mce=bootlog Log MCEs from before booting. Disabled by default on AMD.
  * mce=nobootlog Don't log MCEs from before booting.
+ * mce=bios_cmci_threshold Don't program the CMCI threshold
  */
 static int __init mcheck_enable(char *str)
 {
@@ -1926,6 +1967,8 @@ static int __init mcheck_enable(char *str)
                 mce_ignore_ce = 1;
         else if (!strcmp(str, "bootlog") || !strcmp(str, "nobootlog"))
                 mce_bootlog = (str[0] == 'b');
+        else if (!strcmp(str, "bios_cmci_threshold"))
+                mce_bios_cmci_threshold = 1;
         else if (isdigit(str[0])) {
                 get_option(&str, &tolerant);
                 if (*str == ',') {
@@ -2294,38 +2337,33 @@ mce_cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu)
         unsigned int cpu = (unsigned long)hcpu;
         struct timer_list *t = &per_cpu(mce_timer, cpu);
 
-        switch (action) {
+        switch (action & ~CPU_TASKS_FROZEN) {
         case CPU_ONLINE:
-        case CPU_ONLINE_FROZEN:
                 mce_device_create(cpu);
                 if (threshold_cpu_callback)
                         threshold_cpu_callback(action, cpu);
                 break;
         case CPU_DEAD:
-        case CPU_DEAD_FROZEN:
                 if (threshold_cpu_callback)
                         threshold_cpu_callback(action, cpu);
                 mce_device_remove(cpu);
+                mce_intel_hcpu_update(cpu);
                 break;
         case CPU_DOWN_PREPARE:
-        case CPU_DOWN_PREPARE_FROZEN:
-                del_timer_sync(t);
                 smp_call_function_single(cpu, mce_disable_cpu, &action, 1);
+                del_timer_sync(t);
                 break;
         case CPU_DOWN_FAILED:
-        case CPU_DOWN_FAILED_FROZEN:
-                if (!mce_ignore_ce && check_interval) {
-                        t->expires = round_jiffies(jiffies +
-                                        per_cpu(mce_next_interval, cpu));
-                        add_timer_on(t, cpu);
-                }
                 smp_call_function_single(cpu, mce_reenable_cpu, &action, 1);
+                mce_start_timer(cpu, t);
                 break;
-        case CPU_POST_DEAD:
+        }
+
+        if (action == CPU_POST_DEAD) {
                 /* intentionally ignoring frozen here */
                 cmci_rediscover(cpu);
-                break;
         }
+
         return NOTIFY_OK;
 }
 
diff --git a/arch/x86/kernel/cpu/mcheck/mce_intel.c b/arch/x86/kernel/cpu/mcheck/mce_intel.c
index 38e49bc95ff..5f88abf07e9 100644
--- a/arch/x86/kernel/cpu/mcheck/mce_intel.c
+++ b/arch/x86/kernel/cpu/mcheck/mce_intel.c
@@ -15,6 +15,8 @@
 #include <asm/msr.h>
 #include <asm/mce.h>
 
+#include "mce-internal.h"
+
 /*
  * Support for Intel Correct Machine Check Interrupts. This allows
  * the CPU to raise an interrupt when a corrected machine check happened.
@@ -30,7 +32,22 @@ static DEFINE_PER_CPU(mce_banks_t, mce_banks_owned);
  */
 static DEFINE_RAW_SPINLOCK(cmci_discover_lock);
 
-#define CMCI_THRESHOLD 1
+#define CMCI_THRESHOLD          1
+#define CMCI_POLL_INTERVAL      (30 * HZ)
+#define CMCI_STORM_INTERVAL     (1 * HZ)
+#define CMCI_STORM_THRESHOLD    15
+
+static DEFINE_PER_CPU(unsigned long, cmci_time_stamp);
+static DEFINE_PER_CPU(unsigned int, cmci_storm_cnt);
+static DEFINE_PER_CPU(unsigned int, cmci_storm_state);
+
+enum {
+        CMCI_STORM_NONE,
+        CMCI_STORM_ACTIVE,
+        CMCI_STORM_SUBSIDED,
+};
+
+static atomic_t cmci_storm_on_cpus;
 
 static int cmci_supported(int *banks)
 {
@@ -53,6 +70,93 @@ static int cmci_supported(int *banks)
         return !!(cap & MCG_CMCI_P);
 }
 
+void mce_intel_cmci_poll(void)
+{
+        if (__this_cpu_read(cmci_storm_state) == CMCI_STORM_NONE)
+                return;
+        machine_check_poll(MCP_TIMESTAMP, &__get_cpu_var(mce_banks_owned));
+}
+
+void mce_intel_hcpu_update(unsigned long cpu)
+{
+        if (per_cpu(cmci_storm_state, cpu) == CMCI_STORM_ACTIVE)
+                atomic_dec(&cmci_storm_on_cpus);
+
+        per_cpu(cmci_storm_state, cpu) = CMCI_STORM_NONE;
+}
+
+unsigned long mce_intel_adjust_timer(unsigned long interval)
+{
+        int r;
+
+        if (interval < CMCI_POLL_INTERVAL)
+                return interval;
+
+        switch (__this_cpu_read(cmci_storm_state)) {
+        case CMCI_STORM_ACTIVE:
+                /*
+                 * We switch back to interrupt mode once the poll timer has
+                 * silenced itself. That means no events recorded and the
+                 * timer interval is back to our poll interval.
+                 */
+                __this_cpu_write(cmci_storm_state, CMCI_STORM_SUBSIDED);
+                r = atomic_sub_return(1, &cmci_storm_on_cpus);
+                if (r == 0)
+                        pr_notice("CMCI storm subsided: switching to interrupt mode\n");
+                /* FALLTHROUGH */
+
+        case CMCI_STORM_SUBSIDED:
+                /*
+                 * We wait for all cpus to go back to SUBSIDED
+                 * state. When that happens we switch back to
+                 * interrupt mode.
+                 */
+                if (!atomic_read(&cmci_storm_on_cpus)) {
+                        __this_cpu_write(cmci_storm_state, CMCI_STORM_NONE);
+                        cmci_reenable();
+                        cmci_recheck();
+                }
+                return CMCI_POLL_INTERVAL;
+        default:
+                /*
+                 * We have shiny weather. Let the poll do whatever it
+                 * thinks.
+                 */
+                return interval;
+        }
+}
+
+static bool cmci_storm_detect(void)
+{
+        unsigned int cnt = __this_cpu_read(cmci_storm_cnt);
+        unsigned long ts = __this_cpu_read(cmci_time_stamp);
+        unsigned long now = jiffies;
+        int r;
+
+        if (__this_cpu_read(cmci_storm_state) != CMCI_STORM_NONE)
+                return true;
+
+        if (time_before_eq(now, ts + CMCI_STORM_INTERVAL)) {
+                cnt++;
+        } else {
+                cnt = 1;
+                __this_cpu_write(cmci_time_stamp, now);
+        }
+        __this_cpu_write(cmci_storm_cnt, cnt);
+
+        if (cnt <= CMCI_STORM_THRESHOLD)
+                return false;
+
+        cmci_clear();
+        __this_cpu_write(cmci_storm_state, CMCI_STORM_ACTIVE);
+        r = atomic_add_return(1, &cmci_storm_on_cpus);
+        mce_timer_kick(CMCI_POLL_INTERVAL);
+
+        if (r == 1)
+                pr_notice("CMCI storm detected: switching to poll mode\n");
+        return true;
+}
+
 /*
  * The interrupt handler. This is called on every event.
  * Just call the poller directly to log any events.
@@ -61,33 +165,28 @@ static int cmci_supported(int *banks)
  */
 static void intel_threshold_interrupt(void)
 {
+        if (cmci_storm_detect())
+                return;
         machine_check_poll(MCP_TIMESTAMP, &__get_cpu_var(mce_banks_owned));
         mce_notify_irq();
 }
 
-static void print_update(char *type, int *hdr, int num)
-{
-        if (*hdr == 0)
-                printk(KERN_INFO "CPU %d MCA banks", smp_processor_id());
-        *hdr = 1;
-        printk(KERN_CONT " %s:%d", type, num);
-}
-
 /*
  * Enable CMCI (Corrected Machine Check Interrupt) for available MCE banks
  * on this CPU. Use the algorithm recommended in the SDM to discover shared
  * banks.
  */
-static void cmci_discover(int banks, int boot)
+static void cmci_discover(int banks)
 {
         unsigned long *owned = (void *)&__get_cpu_var(mce_banks_owned);
         unsigned long flags;
-        int hdr = 0;
         int i;
+        int bios_wrong_thresh = 0;
 
         raw_spin_lock_irqsave(&cmci_discover_lock, flags);
         for (i = 0; i < banks; i++) {
                 u64 val;
+                int bios_zero_thresh = 0;
 
                 if (test_bit(i, owned))
                         continue;
@@ -96,29 +195,52 @@ static void cmci_discover(int banks, int boot)
 
                 /* Already owned by someone else? */
                 if (val & MCI_CTL2_CMCI_EN) {
-                        if (test_and_clear_bit(i, owned) && !boot)
-                                print_update("SHD", &hdr, i);
+                        clear_bit(i, owned);
                         __clear_bit(i, __get_cpu_var(mce_poll_banks));
                         continue;
                 }
 
-                val &= ~MCI_CTL2_CMCI_THRESHOLD_MASK;
-                val |= MCI_CTL2_CMCI_EN | CMCI_THRESHOLD;
+                if (!mce_bios_cmci_threshold) {
+                        val &= ~MCI_CTL2_CMCI_THRESHOLD_MASK;
+                        val |= CMCI_THRESHOLD;
+                } else if (!(val & MCI_CTL2_CMCI_THRESHOLD_MASK)) {
+                        /*
+                         * If bios_cmci_threshold boot option was specified
+                         * but the threshold is zero, we'll try to initialize
+                         * it to 1.
+                         */
+                        bios_zero_thresh = 1;
+                        val |= CMCI_THRESHOLD;
+                }
+
+                val |= MCI_CTL2_CMCI_EN;
                 wrmsrl(MSR_IA32_MCx_CTL2(i), val);
                 rdmsrl(MSR_IA32_MCx_CTL2(i), val);
 
                 /* Did the enable bit stick? -- the bank supports CMCI */
                 if (val & MCI_CTL2_CMCI_EN) {
-                        if (!test_and_set_bit(i, owned) && !boot)
-                                print_update("CMCI", &hdr, i);
+                        set_bit(i, owned);
                         __clear_bit(i, __get_cpu_var(mce_poll_banks));
+                        /*
+                         * We are able to set thresholds for some banks that
+                         * had a threshold of 0. This means the BIOS has not
+                         * set the thresholds properly or does not work with
+                         * this boot option. Note down now and report later.
+                         */
+                        if (mce_bios_cmci_threshold && bios_zero_thresh &&
+                                        (val & MCI_CTL2_CMCI_THRESHOLD_MASK))
+                                bios_wrong_thresh = 1;
                 } else {
                         WARN_ON(!test_bit(i, __get_cpu_var(mce_poll_banks)));
                 }
         }
         raw_spin_unlock_irqrestore(&cmci_discover_lock, flags);
-        if (hdr)
-                printk(KERN_CONT "\n");
+        if (mce_bios_cmci_threshold && bios_wrong_thresh) {
+                pr_info_once(
+                        "bios_cmci_threshold: Some banks do not have valid thresholds set\n");
+                pr_info_once(
+                        "bios_cmci_threshold: Make sure your BIOS supports this boot option\n");
+        }
 }
 
 /*
@@ -156,7 +278,7 @@ void cmci_clear(void)
                         continue;
                 /* Disable CMCI */
                 rdmsrl(MSR_IA32_MCx_CTL2(i), val);
-                val &= ~(MCI_CTL2_CMCI_EN|MCI_CTL2_CMCI_THRESHOLD_MASK);
+                val &= ~MCI_CTL2_CMCI_EN;
                 wrmsrl(MSR_IA32_MCx_CTL2(i), val);
                 __clear_bit(i, __get_cpu_var(mce_banks_owned));
         }
@@ -186,7 +308,7 @@ void cmci_rediscover(int dying)
                         continue;
                 /* Recheck banks in case CPUs don't all have the same */
                 if (cmci_supported(&banks))
-                        cmci_discover(banks, 0);
+                        cmci_discover(banks);
         }
 
         set_cpus_allowed_ptr(current, old);
@@ -200,7 +322,7 @@ void cmci_reenable(void)
 {
         int banks;
         if (cmci_supported(&banks))
-                cmci_discover(banks, 0);
+                cmci_discover(banks);
 }
 
 static void intel_init_cmci(void)
@@ -211,7 +333,7 @@ static void intel_init_cmci(void)
                 return;
 
         mce_threshold_vector = intel_threshold_interrupt;
-        cmci_discover(banks, 1);
+        cmci_discover(banks);
         /*
          * For CPU #0 this runs with still disabled APIC, but that's
          * ok because only the vector is set up. We still do another