Merge branch 'x86-mce-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull MCE changes from Ingo Molnar.

* 'x86-mce-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/mce: Fix return value of mce_chrdev_read() when erst is disabled
  x86/mce: Convert static array of pointers to per-cpu variables
  x86/mce: Replace hard coded hex constants with symbolic defines
  x86/mce: Recognise machine check bank signature for data path error
  x86/mce: Handle "action required" errors
  x86/mce: Add mechanism to safely save information in MCE handler
  x86/mce: Create helper function to save addr/misc when needed
  HWPOISON: Add code to handle "action required" errors.
  HWPOISON: Clean up memory_failure() vs. __memory_failure()

3 files changed, 164 insertions, 64 deletions

diff --git a/arch/x86/kernel/cpu/mcheck/mce-severity.c b/arch/x86/kernel/cpu/mcheck/mce-severity.c
index 7395d5f4272d..0c82091b1652 100644
--- a/arch/x86/kernel/cpu/mcheck/mce-severity.c
+++ b/arch/x86/kernel/cpu/mcheck/mce-severity.c
@@ -54,7 +54,14 @@ static struct severity {
 #define  MASK(x, y)     .mask = x, .result = y
 #define MCI_UC_S (MCI_STATUS_UC|MCI_STATUS_S)
 #define MCI_UC_SAR (MCI_STATUS_UC|MCI_STATUS_S|MCI_STATUS_AR)
+#define MCI_ADDR (MCI_STATUS_ADDRV|MCI_STATUS_MISCV)
 #define MCACOD 0xffff
+/* Architecturally defined codes from SDM Vol. 3B Chapter 15 */
+#define MCACOD_SCRUB    0x00C0  /* 0xC0-0xCF Memory Scrubbing */
+#define MCACOD_SCRUBMSK 0xfff0
+#define MCACOD_L3WB     0x017A  /* L3 Explicit Writeback */
+#define MCACOD_DATA     0x0134  /* Data Load */
+#define MCACOD_INSTR    0x0150  /* Instruction Fetch */
 
         MCESEV(
                 NO, "Invalid",
@@ -102,11 +109,24 @@ static struct severity {
                 SER, BITCLR(MCI_STATUS_S)
                 ),
 
-        /* AR add known MCACODs here */
         MCESEV(
                 PANIC, "Action required with lost events",
                 SER, BITSET(MCI_STATUS_OVER|MCI_UC_SAR)
                 ),
+
+        /* known AR MCACODs: */
+#ifdef  CONFIG_MEMORY_FAILURE
+        MCESEV(
+                KEEP, "HT thread notices Action required: data load error",
+                SER, MASK(MCI_STATUS_OVER|MCI_UC_SAR|MCI_ADDR|MCACOD, MCI_UC_SAR|MCI_ADDR|MCACOD_DATA),
+                MCGMASK(MCG_STATUS_EIPV, 0)
+                ),
+        MCESEV(
+                AR, "Action required: data load error",
+                SER, MASK(MCI_STATUS_OVER|MCI_UC_SAR|MCI_ADDR|MCACOD, MCI_UC_SAR|MCI_ADDR|MCACOD_DATA),
+                USER
+                ),
+#endif
         MCESEV(
                 PANIC, "Action required: unknown MCACOD",
                 SER, MASK(MCI_STATUS_OVER|MCI_UC_SAR, MCI_UC_SAR)
@@ -115,11 +135,11 @@ static struct severity {
         /* known AO MCACODs: */
         MCESEV(
                 AO, "Action optional: memory scrubbing error",
-                SER, MASK(MCI_STATUS_OVER|MCI_UC_SAR|0xfff0, MCI_UC_S|0x00c0)
+                SER, MASK(MCI_STATUS_OVER|MCI_UC_SAR|MCACOD_SCRUBMSK, MCI_UC_S|MCACOD_SCRUB)
                 ),
         MCESEV(
                 AO, "Action optional: last level cache writeback error",
-                SER, MASK(MCI_STATUS_OVER|MCI_UC_SAR|MCACOD, MCI_UC_S|0x017a)
+                SER, MASK(MCI_STATUS_OVER|MCI_UC_SAR|MCACOD, MCI_UC_S|MCACOD_L3WB)
                 ),
         MCESEV(
                 SOME, "Action optional: unknown MCACOD",
diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c
index 5a11ae2e9e91..c614bd4de0f3 100644
--- a/arch/x86/kernel/cpu/mcheck/mce.c
+++ b/arch/x86/kernel/cpu/mcheck/mce.c
@@ -540,6 +540,27 @@ static void mce_report_event(struct pt_regs *regs)
         irq_work_queue(&__get_cpu_var(mce_irq_work));
 }
 
+/*
+ * Read ADDR and MISC registers.
+ */
+static void mce_read_aux(struct mce *m, int i)
+{
+        if (m->status & MCI_STATUS_MISCV)
+                m->misc = mce_rdmsrl(MSR_IA32_MCx_MISC(i));
+        if (m->status & MCI_STATUS_ADDRV) {
+                m->addr = mce_rdmsrl(MSR_IA32_MCx_ADDR(i));
+
+                /*
+                 * Mask the reported address by the reported granularity.
+                 */
+                if (mce_ser && (m->status & MCI_STATUS_MISCV)) {
+                        u8 shift = MCI_MISC_ADDR_LSB(m->misc);
+                        m->addr >>= shift;
+                        m->addr <<= shift;
+                }
+        }
+}
+
 DEFINE_PER_CPU(unsigned, mce_poll_count);
 
 /*
@@ -590,10 +611,7 @@ void machine_check_poll(enum mcp_flags flags, mce_banks_t *b)
                     (m.status & (mce_ser ? MCI_STATUS_S : MCI_STATUS_UC)))
                         continue;
 
-                if (m.status & MCI_STATUS_MISCV)
-                        m.misc = mce_rdmsrl(MSR_IA32_MCx_MISC(i));
-                if (m.status & MCI_STATUS_ADDRV)
-                        m.addr = mce_rdmsrl(MSR_IA32_MCx_ADDR(i));
+                mce_read_aux(&m, i);
 
                 if (!(flags & MCP_TIMESTAMP))
                         m.tsc = 0;
@@ -917,6 +935,49 @@ static void mce_clear_state(unsigned long *toclear)
 }
 
 /*
+ * Need to save faulting physical address associated with a process
+ * in the machine check handler some place where we can grab it back
+ * later in mce_notify_process()
+ */
+#define MCE_INFO_MAX    16
+
+struct mce_info {
+        atomic_t                inuse;
+        struct task_struct      *t;
+        __u64                   paddr;
+} mce_info[MCE_INFO_MAX];
+
+static void mce_save_info(__u64 addr)
+{
+        struct mce_info *mi;
+
+        for (mi = mce_info; mi < &mce_info[MCE_INFO_MAX]; mi++) {
+                if (atomic_cmpxchg(&mi->inuse, 0, 1) == 0) {
+                        mi->t = current;
+                        mi->paddr = addr;
+                        return;
+                }
+        }
+
+        mce_panic("Too many concurrent recoverable errors", NULL, NULL);
+}
+
+static struct mce_info *mce_find_info(void)
+{
+        struct mce_info *mi;
+
+        for (mi = mce_info; mi < &mce_info[MCE_INFO_MAX]; mi++)
+                if (atomic_read(&mi->inuse) && mi->t == current)
+                        return mi;
+        return NULL;
+}
+
+static void mce_clear_info(struct mce_info *mi)
+{
+        atomic_set(&mi->inuse, 0);
+}
+
+/*
  * The actual machine check handler. This only handles real
  * exceptions when something got corrupted coming in through int 18.
  *
@@ -969,7 +1030,9 @@ void do_machine_check(struct pt_regs *regs, long error_code)
         barrier();
 
         /*
-         * When no restart IP must always kill or panic.
+         * When no restart IP might need to kill or panic.
+         * Assume the worst for now, but if we find the
+         * severity is MCE_AR_SEVERITY we have other options.
          */
         if (!(m.mcgstatus & MCG_STATUS_RIPV))
                 kill_it = 1;
@@ -1023,16 +1086,7 @@ void do_machine_check(struct pt_regs *regs, long error_code)
                         continue;
                 }
 
-                /*
-                 * Kill on action required.
-                 */
-                if (severity == MCE_AR_SEVERITY)
-                        kill_it = 1;
-
-                if (m.status & MCI_STATUS_MISCV)
-                        m.misc = mce_rdmsrl(MSR_IA32_MCx_MISC(i));
-                if (m.status & MCI_STATUS_ADDRV)
-                        m.addr = mce_rdmsrl(MSR_IA32_MCx_ADDR(i));
+                mce_read_aux(&m, i);
 
                 /*
                  * Action optional error. Queue address for later processing.
@@ -1052,6 +1106,9 @@ void do_machine_check(struct pt_regs *regs, long error_code)
                 }
         }
 
+        /* mce_clear_state will clear *final, save locally for use later */
+        m = *final;
+
         if (!no_way_out)
                 mce_clear_state(toclear);
 
@@ -1063,27 +1120,22 @@ void do_machine_check(struct pt_regs *regs, long error_code)
                 no_way_out = worst >= MCE_PANIC_SEVERITY;
 
         /*
-         * If we have decided that we just CAN'T continue, and the user
-         * has not set tolerant to an insane level, give up and die.
-         *
-         * This is mainly used in the case when the system doesn't
-         * support MCE broadcasting or it has been disabled.
-         */
-        if (no_way_out && tolerant < 3)
-                mce_panic("Fatal machine check on current CPU", final, msg);
-
-        /*
-         * If the error seems to be unrecoverable, something should be
-         * done.  Try to kill as little as possible.  If we can kill just
-         * one task, do that.  If the user has set the tolerance very
-         * high, don't try to do anything at all.
+         * At insane "tolerant" levels we take no action. Otherwise
+         * we only die if we have no other choice. For less serious
+         * issues we try to recover, or limit damage to the current
+         * process.
          */
-
-        if (kill_it && tolerant < 3)
-                force_sig(SIGBUS, current);
-
-        /* notify userspace ASAP */
-        set_thread_flag(TIF_MCE_NOTIFY);
+        if (tolerant < 3) {
+                if (no_way_out)
+                        mce_panic("Fatal machine check on current CPU", &m, msg);
+                if (worst == MCE_AR_SEVERITY) {
+                        /* schedule action before return to userland */
+                        mce_save_info(m.addr);
+                        set_thread_flag(TIF_MCE_NOTIFY);
+                } else if (kill_it) {
+                        force_sig(SIGBUS, current);
+                }
+        }
 
         if (worst > 0)
                 mce_report_event(regs);
@@ -1094,34 +1146,57 @@ out:
 }
 EXPORT_SYMBOL_GPL(do_machine_check);
 
-/* dummy to break dependency. actual code is in mm/memory-failure.c */
-void __attribute__((weak)) memory_failure(unsigned long pfn, int vector)
+#ifndef CONFIG_MEMORY_FAILURE
+int memory_failure(unsigned long pfn, int vector, int flags)
 {
-        printk(KERN_ERR "Action optional memory failure at %lx ignored\n", pfn);
+        /* mce_severity() should not hand us an ACTION_REQUIRED error */
+        BUG_ON(flags & MF_ACTION_REQUIRED);
+        printk(KERN_ERR "Uncorrected memory error in page 0x%lx ignored\n"
+                "Rebuild kernel with CONFIG_MEMORY_FAILURE=y for smarter handling\n", pfn);
+
+        return 0;
 }
+#endif
 
 /*
- * Called after mce notification in process context. This code
- * is allowed to sleep. Call the high level VM handler to process
- * any corrupted pages.
- * Assume that the work queue code only calls this one at a time
- * per CPU.
- * Note we don't disable preemption, so this code might run on the wrong
- * CPU. In this case the event is picked up by the scheduled work queue.
- * This is merely a fast path to expedite processing in some common
- * cases.
+ * Called in process context that interrupted by MCE and marked with
+ * TIF_MCE_NOTIFY, just before returning to erroneous userland.
+ * This code is allowed to sleep.
+ * Attempt possible recovery such as calling the high level VM handler to
+ * process any corrupted pages, and kill/signal current process if required.
+ * Action required errors are handled here.
  */
 void mce_notify_process(void)
 {
         unsigned long pfn;
-        mce_notify_irq();
-        while (mce_ring_get(&pfn))
-                memory_failure(pfn, MCE_VECTOR);
+        struct mce_info *mi = mce_find_info();
+
+        if (!mi)
+                mce_panic("Lost physical address for unconsumed uncorrectable error", NULL, NULL);
+        pfn = mi->paddr >> PAGE_SHIFT;
+
+        clear_thread_flag(TIF_MCE_NOTIFY);
+
+        pr_err("Uncorrected hardware memory error in user-access at %llx",
+                 mi->paddr);
+        if (memory_failure(pfn, MCE_VECTOR, MF_ACTION_REQUIRED) < 0) {
+                pr_err("Memory error not recovered");
+                force_sig(SIGBUS, current);
+        }
+        mce_clear_info(mi);
 }
 
+/*
+ * Action optional processing happens here (picking up
+ * from the list of faulting pages that do_machine_check()
+ * placed into the "ring").
+ */
 static void mce_process_work(struct work_struct *dummy)
 {
-        mce_notify_process();
+        unsigned long pfn;
+
+        while (mce_ring_get(&pfn))
+                memory_failure(pfn, MCE_VECTOR, 0);
 }
 
 #ifdef CONFIG_X86_MCE_INTEL
@@ -1211,8 +1286,6 @@ int mce_notify_irq(void)
         /* Not more than two messages every minute */
         static DEFINE_RATELIMIT_STATE(ratelimit, 60*HZ, 2);
 
-        clear_thread_flag(TIF_MCE_NOTIFY);
-
         if (test_and_clear_bit(0, &mce_need_notify)) {
                 /* wake processes polling /dev/mcelog */
                 wake_up_interruptible(&mce_chrdev_wait);
@@ -1541,6 +1614,12 @@ static int __mce_read_apei(char __user **ubuf, size_t usize)
         /* Error or no more MCE record */
         if (rc <= 0) {
                 mce_apei_read_done = 1;
+                /*
+                 * When ERST is disabled, mce_chrdev_read() should return
+                 * "no record" instead of "no device."
+                 */
+                if (rc == -ENODEV)
+                        return 0;
                 return rc;
         }
         rc = -EFAULT;
@@ -1859,7 +1938,7 @@ static struct bus_type mce_subsys = {
         .dev_name       = "machinecheck",
 };
 
-struct device *mce_device[CONFIG_NR_CPUS];
+DEFINE_PER_CPU(struct device *, mce_device);
 
 __cpuinitdata
 void (*threshold_cpu_callback)(unsigned long action, unsigned int cpu);
@@ -2038,7 +2117,7 @@ static __cpuinit int mce_device_create(unsigned int cpu)
                         goto error2;
         }
         cpumask_set_cpu(cpu, mce_device_initialized);
-        mce_device[cpu] = dev;
+        per_cpu(mce_device, cpu) = dev;
 
         return 0;
 error2:
@@ -2055,7 +2134,7 @@ error:
 
 static __cpuinit void mce_device_remove(unsigned int cpu)
 {
-        struct device *dev = mce_device[cpu];
+        struct device *dev = per_cpu(mce_device, cpu);
         int i;
 
         if (!cpumask_test_cpu(cpu, mce_device_initialized))
@@ -2069,7 +2148,7 @@ static __cpuinit void mce_device_remove(unsigned int cpu)
 
         device_unregister(dev);
         cpumask_clear_cpu(cpu, mce_device_initialized);
-        mce_device[cpu] = NULL;
+        per_cpu(mce_device, cpu) = NULL;
 }
 
 /* Make sure there are no machine checks on offlined CPUs. */
diff --git a/arch/x86/kernel/cpu/mcheck/mce_amd.c b/arch/x86/kernel/cpu/mcheck/mce_amd.c
index e4eeaaf58a47..99b57179f912 100644
--- a/arch/x86/kernel/cpu/mcheck/mce_amd.c
+++ b/arch/x86/kernel/cpu/mcheck/mce_amd.c
@@ -523,7 +523,7 @@ static __cpuinit int threshold_create_bank(unsigned int cpu, unsigned int bank)
 {
         int i, err = 0;
         struct threshold_bank *b = NULL;
-        struct device *dev = mce_device[cpu];
+        struct device *dev = per_cpu(mce_device, cpu);
         char name[32];
 
         sprintf(name, "threshold_bank%i", bank);
@@ -587,7 +587,7 @@ static __cpuinit int threshold_create_bank(unsigned int cpu, unsigned int bank)
                 if (i == cpu)
                         continue;
 
-                dev = mce_device[i];
+                dev = per_cpu(mce_device, i);
                 if (dev)
                         err = sysfs_create_link(&dev->kobj,b->kobj, name);
                 if (err)
@@ -667,7 +667,8 @@ static void threshold_remove_bank(unsigned int cpu, int bank)
 #ifdef CONFIG_SMP
         /* sibling symlink */
         if (shared_bank[bank] && b->blocks->cpu != cpu) {
-                sysfs_remove_link(&mce_device[cpu]->kobj, name);
+                dev = per_cpu(mce_device, cpu);
+                sysfs_remove_link(&dev->kobj, name);
                 per_cpu(threshold_banks, cpu)[bank] = NULL;
 
                 return;
@@ -679,7 +680,7 @@ static void threshold_remove_bank(unsigned int cpu, int bank)
                 if (i == cpu)
                         continue;
 
-                dev = mce_device[i];
+                dev = per_cpu(mce_device, i);
                 if (dev)
                         sysfs_remove_link(&dev->kobj, name);
                 per_cpu(threshold_banks, i)[bank] = NULL;