x86: Enable NMI on all cpus on UV

Enable NMI on all cpus in UV system and add an NMI handler
to dump_stack on each cpu.

By default on x86 all the cpus except the boot cpu have NMI
masked off.  This patch enables NMI on all cpus in UV system
and adds an NMI handler to dump_stack on each cpu.  This
way if a system hangs we can NMI the machine and get a
backtrace from all the cpus.

Version 2: Use x86_platform driver mechanism for nmi init, per
           Ingo's suggestion.

Version 3: Clean up Ingo's nits.

Signed-off-by: Russ Anderson <rja@sgi.com>
LKML-Reference: <20100226164912.GA24439@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/arch/x86/include/asm/uv/uv.h b/arch/x86/include/asm/uv/uv.h
index c0a01b5d985bec4078e60c1856fcb1c1e7c99376..3bb9491b76590d6d9b5281f43e6e0e0d1ff4ccd2 100644 (file)
--- a/arch/x86/include/asm/uv/uv.h
+++ b/arch/x86/include/asm/uv/uv.h
@@ -11,6 +11,7 @@ struct mm_struct;
 extern enum uv_system_type get_uv_system_type(void);
 extern int is_uv_system(void);
 extern void uv_cpu_init(void);
+extern void uv_nmi_init(void);
 extern void uv_system_init(void);
 extern const struct cpumask *uv_flush_tlb_others(const struct cpumask *cpumask,
                                                 struct mm_struct *mm,

diff --git a/arch/x86/include/asm/x86_init.h b/arch/x86/include/asm/x86_init.h
index ea0e8ea15e155e6033c34b9ec3bab17f7cc28f9c..60cc3526908377d98fe787f5956cf34c1f2346eb 100644 (file)
--- a/arch/x86/include/asm/x86_init.h
+++ b/arch/x86/include/asm/x86_init.h
@@ -126,6 +126,7 @@ struct x86_cpuinit_ops {
  * @get_wallclock:             get time from HW clock like RTC etc.
  * @set_wallclock:             set time back to HW clock
  * @is_untracked_pat_range     exclude from PAT logic
+ * @nmi_init                   enable NMI on cpus
  */
 struct x86_platform_ops {
        unsigned long (*calibrate_tsc)(void);
@@ -133,6 +134,7 @@ struct x86_platform_ops {
        int (*set_wallclock)(unsigned long nowtime);
        void (*iommu_shutdown)(void);
        bool (*is_untracked_pat_range)(u64 start, u64 end);
+       void (*nmi_init)(void);
 };
 
 extern struct x86_init_ops x86_init;

diff --git a/arch/x86/kernel/apic/x2apic_uv_x.c b/arch/x86/kernel/apic/x2apic_uv_x.c
index 6ef2899eb8618ee7d36d56c3aacff637b1eee5d9..4b8dbb25614705fea572d1efe2c475de807cdb61 100644 (file)
--- a/arch/x86/kernel/apic/x2apic_uv_x.c
+++ b/arch/x86/kernel/apic/x2apic_uv_x.c
@@ -21,6 +21,7 @@
 #include <linux/init.h>
 #include <linux/io.h>
 #include <linux/pci.h>
+#include <linux/kdebug.h>
 
 #include <asm/uv/uv_mmrs.h>
 #include <asm/uv/uv_hub.h>
@@ -41,6 +42,7 @@ static enum uv_system_type uv_system_type;
 static u64 gru_start_paddr, gru_end_paddr;
 int uv_min_hub_revision_id;
 EXPORT_SYMBOL_GPL(uv_min_hub_revision_id);
+static DEFINE_SPINLOCK(uv_nmi_lock);
 
 static inline bool is_GRU_range(u64 start, u64 end)
 {
@@ -74,6 +76,7 @@ static int __init uv_acpi_madt_oem_check(char *oem_id, char *oem_table_id)
        if (!strcmp(oem_id, "SGI")) {
                nodeid = early_get_nodeid();
                x86_platform.is_untracked_pat_range =  uv_is_untracked_pat_range;
+               x86_platform.nmi_init = uv_nmi_init;
                if (!strcmp(oem_table_id, "UVL"))
                        uv_system_type = UV_LEGACY_APIC;
                else if (!strcmp(oem_table_id, "UVX"))
@@ -596,6 +599,46 @@ void __cpuinit uv_cpu_init(void)
                set_x2apic_extra_bits(uv_hub_info->pnode);
 }
 
+/*
+ * When NMI is received, print a stack trace.
+ */
+int uv_handle_nmi(struct notifier_block *self, unsigned long reason, void *data)
+{
+       if (reason != DIE_NMI_IPI)
+               return NOTIFY_OK;
+       /*
+        * Use a lock so only one cpu prints at a time
+        * to prevent intermixed output.
+        */
+       spin_lock(&uv_nmi_lock);
+       pr_info("NMI stack dump cpu %u:\n", smp_processor_id());
+       dump_stack();
+       spin_unlock(&uv_nmi_lock);
+
+       return NOTIFY_STOP;
+}
+
+static struct notifier_block uv_dump_stack_nmi_nb = {
+       .notifier_call  = uv_handle_nmi
+};
+
+void uv_register_nmi_notifier(void)
+{
+       if (register_die_notifier(&uv_dump_stack_nmi_nb))
+               printk(KERN_WARNING "UV NMI handler failed to register\n");
+}
+
+void uv_nmi_init(void)
+{
+       unsigned int value;
+
+       /*
+        * Unmask NMI on all cpus
+        */
+       value = apic_read(APIC_LVT1) | APIC_DM_NMI;
+       value &= ~APIC_LVT_MASKED;
+       apic_write(APIC_LVT1, value);
+}
 
 void __init uv_system_init(void)
 {
@@ -717,6 +760,7 @@ void __init uv_system_init(void)
 
        uv_cpu_init();
        uv_scir_register_cpu_notifier();
+       uv_register_nmi_notifier();
        proc_mkdir("sgi_uv", NULL);
 
        /* register Legacy VGA I/O redirection handler */

diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 678d0b8c26f3152c67a833f3e782cb15c9d0a61b..838a118876c01d004b888f9b05a19efb215c86a5 100644 (file)
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -320,6 +320,7 @@ notrace static void __cpuinit start_secondary(void *unused)
        unlock_vector_lock();
        ipi_call_unlock();
        per_cpu(cpu_state, smp_processor_id()) = CPU_ONLINE;
+       x86_platform.nmi_init();
 
        /* enable local interrupts */
        local_irq_enable();

diff --git a/arch/x86/kernel/x86_init.c b/arch/x86/kernel/x86_init.c
index ccd179dec36e8f82da0b6484e7307dda16a7ed30..ee5746c946283284db77d153354ffa962b028c9f 100644 (file)
--- a/arch/x86/kernel/x86_init.c
+++ b/arch/x86/kernel/x86_init.c
@@ -76,10 +76,13 @@ struct x86_cpuinit_ops x86_cpuinit __cpuinitdata = {
        .setup_percpu_clockev           = setup_secondary_APIC_clock,
 };
 
+static void default_nmi_init(void) { };
+
 struct x86_platform_ops x86_platform = {
        .calibrate_tsc                  = native_calibrate_tsc,
        .get_wallclock                  = mach_get_cmos_time,
        .set_wallclock                  = mach_set_rtc_mmss,
        .iommu_shutdown                 = iommu_shutdown_noop,
        .is_untracked_pat_range         = is_ISA_range,
+       .nmi_init                       = default_nmi_init
 };