[patch 4/8] Add SMP support on x86_64 to reservation framework

From: dzickus
Date: Tue May 09 2006 - 16:58:09 EST


This patch includes the changes to make the nmi watchdog on x86_64 SMP
aware. A bunch of code was moved around to make it simpler to read. In
addition, it is now possible to determine if a particular NMI was the result
of the watchdog or not. This feature allows the kernel to filter out
unknown NMIs easier.

Signed-off-by: Don Zickus <dzickus@xxxxxxxxxx>


Index: linux-don/arch/x86_64/kernel/apic.c
===================================================================
--- linux-don.orig/arch/x86_64/kernel/apic.c
+++ linux-don/arch/x86_64/kernel/apic.c
@@ -480,8 +480,7 @@ void __cpuinit setup_local_APIC (void)
}

nmi_watchdog_default();
- if (nmi_watchdog == NMI_LOCAL_APIC)
- setup_apic_nmi_watchdog();
+ setup_apic_nmi_watchdog(NULL);
apic_pm_activate();
}

Index: linux-don/arch/x86_64/kernel/nmi.c
===================================================================
--- linux-don.orig/arch/x86_64/kernel/nmi.c
+++ linux-don/arch/x86_64/kernel/nmi.c
@@ -57,53 +57,29 @@ static unsigned int lapic_nmi_owner;
#define LAPIC_NMI_RESERVED (1<<1)

/* nmi_active:
- * +1: the lapic NMI watchdog is active, but can be disabled
- * 0: the lapic NMI watchdog has not been set up, and cannot
+ * >0: the lapic NMI watchdog is active, but can be disabled
+ * <0: the lapic NMI watchdog has not been set up, and cannot
* be enabled
- * -1: the lapic NMI watchdog is disabled, but can be enabled
+ * 0: the lapic NMI watchdog is disabled, but can be enabled
*/
-int nmi_active; /* oprofile uses this */
+atomic_t nmi_active = ATOMIC_INIT(0); /* oprofile uses this */
int panic_on_timeout;

unsigned int nmi_watchdog = NMI_DEFAULT;
static unsigned int nmi_hz = HZ;
-static unsigned int nmi_perfctr_msr; /* the MSR to reset in NMI handler */
-static unsigned int nmi_p4_cccr_val;

-/* Note that these events don't tick when the CPU idles. This means
- the frequency varies with CPU load. */
-
-#define K7_EVNTSEL_ENABLE (1 << 22)
-#define K7_EVNTSEL_INT (1 << 20)
-#define K7_EVNTSEL_OS (1 << 17)
-#define K7_EVNTSEL_USR (1 << 16)
-#define K7_EVENT_CYCLES_PROCESSOR_IS_RUNNING 0x76
-#define K7_NMI_EVENT K7_EVENT_CYCLES_PROCESSOR_IS_RUNNING
+struct nmi_watchdog_ctlblk {
+ int enabled;
+ u64 check_bit;
+ unsigned int cccr_msr;
+ unsigned int perfctr_msr; /* the MSR to reset in NMI handler */
+ unsigned int evntsel_msr; /* the MSR to select the events to handle */
+};
+static DEFINE_PER_CPU(struct nmi_watchdog_ctlblk, nmi_watchdog_ctlblk);

-#define MSR_P4_MISC_ENABLE 0x1A0
-#define MSR_P4_MISC_ENABLE_PERF_AVAIL (1<<7)
-#define MSR_P4_MISC_ENABLE_PEBS_UNAVAIL (1<<12)
-#define MSR_P4_PERFCTR0 0x300
-#define MSR_P4_CCCR0 0x360
-#define P4_ESCR_EVENT_SELECT(N) ((N)<<25)
-#define P4_ESCR_OS (1<<3)
-#define P4_ESCR_USR (1<<2)
-#define P4_CCCR_OVF_PMI0 (1<<26)
-#define P4_CCCR_OVF_PMI1 (1<<27)
-#define P4_CCCR_THRESHOLD(N) ((N)<<20)
-#define P4_CCCR_COMPLEMENT (1<<19)
-#define P4_CCCR_COMPARE (1<<18)
-#define P4_CCCR_REQUIRED (3<<16)
-#define P4_CCCR_ESCR_SELECT(N) ((N)<<13)
-#define P4_CCCR_ENABLE (1<<12)
-/* Set up IQ_COUNTER0 to behave like a clock, by having IQ_CCCR0 filter
- CRU_ESCR0 (with any non-null event selector) through a complemented
- max threshold. [IA32-Vol3, Section 14.9.9] */
-#define MSR_P4_IQ_COUNTER0 0x30C
-#define P4_NMI_CRU_ESCR0 (P4_ESCR_EVENT_SELECT(0x3F)|P4_ESCR_OS|P4_ESCR_USR)
-#define P4_NMI_IQ_CCCR0 \
- (P4_CCCR_OVF_PMI0|P4_CCCR_THRESHOLD(15)|P4_CCCR_COMPLEMENT| \
- P4_CCCR_COMPARE|P4_CCCR_REQUIRED|P4_CCCR_ESCR_SELECT(4)|P4_CCCR_ENABLE)
+/* local prototypes */
+static void stop_apic_nmi_watchdog(void *unused);
+static int unknown_nmi_panic_callback(struct pt_regs *regs, int cpu);

/* converts an msr to an appropriate reservation bit */
static inline unsigned int nmi_perfctr_msr_to_bit(unsigned int msr)
@@ -242,6 +218,12 @@ int __init check_nmi_watchdog (void)
int *counts;
int cpu;

+ if ((nmi_watchdog == NMI_NONE) || (nmi_watchdog == NMI_DEFAULT))
+ return 0;
+
+ if (!atomic_read(&nmi_active))
+ return 0;
+
counts = kmalloc(NR_CPUS * sizeof(int), GFP_KERNEL);
if (!counts)
return -1;
@@ -259,19 +241,22 @@ int __init check_nmi_watchdog (void)
mdelay((10*1000)/nmi_hz); // wait 10 ticks

for_each_online_cpu(cpu) {
+ if (!per_cpu(nmi_watchdog_ctlblk.enabled, cpu))
+ continue;
if (cpu_pda(cpu)->__nmi_count - counts[cpu] <= 5) {
- endflag = 1;
printk("CPU#%d: NMI appears to be stuck (%d->%d)!\n",
cpu,
counts[cpu],
cpu_pda(cpu)->__nmi_count);
- nmi_active = 0;
- lapic_nmi_owner &= ~LAPIC_NMI_WATCHDOG;
- nmi_perfctr_msr = 0;
- kfree(counts);
- return -1;
+ per_cpu(nmi_watchdog_ctlblk.enabled, cpu) = 0;
+ atomic_dec(&nmi_active);
}
}
+ if (!atomic_read(&nmi_active)) {
+ kfree(counts);
+ atomic_set(&nmi_active, -1);
+ return -1;
+ }
endflag = 1;
printk("OK.\n");

@@ -298,8 +283,11 @@ int __init setup_nmi_watchdog(char *str)

get_option(&str, &nmi);

- if (nmi >= NMI_INVALID)
+ if ((nmi >= NMI_INVALID) || (nmi < NMI_NONE))
return 0;
+
+ if ((nmi == NMI_LOCAL_APIC) && (nmi_known_cpu() == 0))
+ return 0; /* no lapic support */
nmi_watchdog = nmi;
return 1;
}
@@ -308,31 +296,30 @@ __setup("nmi_watchdog=", setup_nmi_watch

static void disable_lapic_nmi_watchdog(void)
{
- if (nmi_active <= 0)
+ BUG_ON(nmi_watchdog != NMI_LOCAL_APIC);
+
+ if (atomic_read(&nmi_active) <= 0)
return;
- switch (boot_cpu_data.x86_vendor) {
- case X86_VENDOR_AMD:
- wrmsr(MSR_K7_EVNTSEL0, 0, 0);
- break;
- case X86_VENDOR_INTEL:
- if (boot_cpu_data.x86 == 15) {
- wrmsr(MSR_P4_IQ_CCCR0, 0, 0);
- wrmsr(MSR_P4_CRU_ESCR0, 0, 0);
- }
- break;
- }
- nmi_active = -1;
- /* tell do_nmi() and others that we're not active any more */
- nmi_watchdog = 0;
+
+ on_each_cpu(stop_apic_nmi_watchdog, NULL, 0, 1);
+
+ BUG_ON(atomic_read(&nmi_active) != 0);
}

static void enable_lapic_nmi_watchdog(void)
{
- if (nmi_active < 0) {
- nmi_watchdog = NMI_LOCAL_APIC;
- touch_nmi_watchdog();
- setup_apic_nmi_watchdog();
- }
+ BUG_ON(nmi_watchdog != NMI_LOCAL_APIC);
+
+ /* are we already enabled */
+ if (atomic_read(&nmi_active) != 0)
+ return;
+
+ /* are we lapic aware */
+ if (nmi_known_cpu() <= 0)
+ return;
+
+ on_each_cpu(setup_apic_nmi_watchdog, NULL, 0, 1);
+ touch_nmi_watchdog();
}

int reserve_lapic_nmi(void)
@@ -364,21 +351,24 @@ void release_lapic_nmi(void)

void disable_timer_nmi_watchdog(void)
{
- if ((nmi_watchdog != NMI_IO_APIC) || (nmi_active <= 0))
+ BUG_ON(nmi_watchdog != NMI_IO_APIC);
+
+ if (atomic_read(&nmi_active) <= 0)
return;

disable_irq(0);
- unset_nmi_callback();
- nmi_active = -1;
- nmi_watchdog = NMI_NONE;
+ on_each_cpu(stop_apic_nmi_watchdog, NULL, 0, 1);
+
+ BUG_ON(atomic_read(&nmi_active) != 0);
}

void enable_timer_nmi_watchdog(void)
{
- if (nmi_active < 0) {
- nmi_watchdog = NMI_IO_APIC;
+ BUG_ON(nmi_watchdog != NMI_IO_APIC);
+
+ if (atomic_read(&nmi_active) == 0) {
touch_nmi_watchdog();
- nmi_active = 1;
+ on_each_cpu(setup_apic_nmi_watchdog, NULL, 0, 1);
enable_irq(0);
}
}
@@ -389,7 +379,7 @@ static int nmi_pm_active; /* nmi_active

static int lapic_nmi_suspend(struct sys_device *dev, pm_message_t state)
{
- nmi_pm_active = nmi_active;
+ nmi_pm_active = atomic_read(&nmi_active);
disable_lapic_nmi_watchdog();
return 0;
}
@@ -397,7 +387,7 @@ static int lapic_nmi_suspend(struct sys_
static int lapic_nmi_resume(struct sys_device *dev)
{
if (nmi_pm_active > 0)
- enable_lapic_nmi_watchdog();
+ enable_lapic_nmi_watchdog();
return 0;
}

@@ -416,7 +406,13 @@ static int __init init_lapic_nmi_sysfs(v
{
int error;

- if (nmi_active == 0 || nmi_watchdog != NMI_LOCAL_APIC)
+ /* should really be a BUG_ON but b/c this is an
+ * init call, it just doesn't work. -dcz
+ */
+ if (nmi_watchdog != NMI_LOCAL_APIC)
+ return 0;
+
+ if ( atomic_read(&nmi_active) < 0 )
return 0;

error = sysdev_class_register(&nmi_sysclass);
@@ -429,100 +425,232 @@ late_initcall(init_lapic_nmi_sysfs);

#endif /* CONFIG_PM */

+/*
+ * Activate the NMI watchdog via the local APIC.
+ * Original code written by Keith Owens.
+ */
+
+/* Note that these events don't tick when the CPU idles. This means
+ the frequency varies with CPU load. */
+
+#define K7_EVNTSEL_ENABLE (1 << 22)
+#define K7_EVNTSEL_INT (1 << 20)
+#define K7_EVNTSEL_OS (1 << 17)
+#define K7_EVNTSEL_USR (1 << 16)
+#define K7_EVENT_CYCLES_PROCESSOR_IS_RUNNING 0x76
+#define K7_NMI_EVENT K7_EVENT_CYCLES_PROCESSOR_IS_RUNNING
+
static int setup_k7_watchdog(void)
{
+ unsigned int perfctr_msr, evntsel_msr;
unsigned int evntsel;
+ struct nmi_watchdog_ctlblk *wd = &__get_cpu_var(nmi_watchdog_ctlblk);

- nmi_perfctr_msr = MSR_K7_PERFCTR0;
-
- if (!reserve_perfctr_nmi(nmi_perfctr_msr))
+ perfctr_msr = MSR_K7_PERFCTR0;
+ evntsel_msr = MSR_K7_EVNTSEL0;
+ if (!reserve_perfctr_nmi(perfctr_msr))
goto fail;

- if (!reserve_evntsel_nmi(MSR_K7_EVNTSEL0))
+ if (!reserve_evntsel_nmi(evntsel_msr))
goto fail1;

/* Simulator may not support it */
- if (checking_wrmsrl(MSR_K7_EVNTSEL0, 0UL))
+ if (checking_wrmsrl(evntsel_msr, 0UL))
goto fail2;
- wrmsrl(MSR_K7_PERFCTR0, 0UL);
+ wrmsrl(perfctr_msr, 0UL);

evntsel = K7_EVNTSEL_INT
| K7_EVNTSEL_OS
| K7_EVNTSEL_USR
| K7_NMI_EVENT;

- wrmsr(MSR_K7_EVNTSEL0, evntsel, 0);
- wrmsrl(MSR_K7_PERFCTR0, -((u64)cpu_khz * 1000 / nmi_hz));
+ /* setup the timer */
+ wrmsr(evntsel_msr, evntsel, 0);
+ wrmsrl(perfctr_msr, -((u64)cpu_khz * 1000 / nmi_hz));
apic_write(APIC_LVTPC, APIC_DM_NMI);
evntsel |= K7_EVNTSEL_ENABLE;
- wrmsr(MSR_K7_EVNTSEL0, evntsel, 0);
+ wrmsr(evntsel_msr, evntsel, 0);
+
+ wd->perfctr_msr = perfctr_msr;
+ wd->evntsel_msr = evntsel_msr;
+ wd->cccr_msr = 0; //unused
+ wd->check_bit = 1ULL<<63;
return 1;
fail2:
- release_evntsel_nmi(MSR_K7_EVNTSEL0);
+ release_evntsel_nmi(evntsel_msr);
fail1:
- release_perfctr_nmi(nmi_perfctr_msr);
+ release_perfctr_nmi(perfctr_msr);
fail:
return 0;
}

+static void stop_k7_watchdog(void)
+{
+ struct nmi_watchdog_ctlblk *wd = &__get_cpu_var(nmi_watchdog_ctlblk);
+
+ wrmsr(wd->evntsel_msr, 0, 0);
+
+ release_evntsel_nmi(wd->evntsel_msr);
+ release_perfctr_nmi(wd->perfctr_msr);
+}
+
+/* Note that these events don't tick when the CPU idles. This means
+ the frequency varies with CPU load. */
+
+#define MSR_P4_MISC_ENABLE_PERF_AVAIL (1<<7)
+#define P4_ESCR_EVENT_SELECT(N) ((N)<<25)
+#define P4_ESCR_OS (1<<3)
+#define P4_ESCR_USR (1<<2)
+#define P4_CCCR_OVF_PMI0 (1<<26)
+#define P4_CCCR_OVF_PMI1 (1<<27)
+#define P4_CCCR_THRESHOLD(N) ((N)<<20)
+#define P4_CCCR_COMPLEMENT (1<<19)
+#define P4_CCCR_COMPARE (1<<18)
+#define P4_CCCR_REQUIRED (3<<16)
+#define P4_CCCR_ESCR_SELECT(N) ((N)<<13)
+#define P4_CCCR_ENABLE (1<<12)
+#define P4_CCCR_OVF (1<<31)
+/* Set up IQ_COUNTER0 to behave like a clock, by having IQ_CCCR0 filter
+ CRU_ESCR0 (with any non-null event selector) through a complemented
+ max threshold. [IA32-Vol3, Section 14.9.9] */

static int setup_p4_watchdog(void)
{
+ unsigned int perfctr_msr, evntsel_msr, cccr_msr;
+ unsigned int evntsel, cccr_val;
unsigned int misc_enable, dummy;
+ unsigned int ht_num;
+ struct nmi_watchdog_ctlblk *wd = &__get_cpu_var(nmi_watchdog_ctlblk);

- rdmsr(MSR_P4_MISC_ENABLE, misc_enable, dummy);
+ rdmsr(MSR_IA32_MISC_ENABLE, misc_enable, dummy);
if (!(misc_enable & MSR_P4_MISC_ENABLE_PERF_AVAIL))
return 0;

- nmi_perfctr_msr = MSR_P4_IQ_COUNTER0;
- nmi_p4_cccr_val = P4_NMI_IQ_CCCR0;
#ifdef CONFIG_SMP
- if (smp_num_siblings == 2)
- nmi_p4_cccr_val |= P4_CCCR_OVF_PMI1;
+ /* detect which hyperthread we are on */
+ if (smp_num_siblings == 2) {
+ unsigned int ebx, apicid;
+
+ ebx = cpuid_ebx(1);
+ apicid = (ebx >> 24) & 0xff;
+ ht_num = apicid & 1;
+ } else
#endif
+ ht_num = 0;
+
+ /* performance counters are shared resources
+ * assign each hyperthread its own set
+ * (re-use the ESCR0 register, seems safe
+ * and keeps the cccr_val the same)
+ */
+ if (!ht_num) {
+ /* logical cpu 0 */
+ perfctr_msr = MSR_P4_IQ_PERFCTR0;
+ evntsel_msr = MSR_P4_CRU_ESCR0;
+ cccr_msr = MSR_P4_IQ_CCCR0;
+ cccr_val = P4_CCCR_OVF_PMI0 | P4_CCCR_ESCR_SELECT(4);
+ } else {
+ /* logical cpu 1 */
+ perfctr_msr = MSR_P4_IQ_PERFCTR1;
+ evntsel_msr = MSR_P4_CRU_ESCR0;
+ cccr_msr = MSR_P4_IQ_CCCR1;
+ cccr_val = P4_CCCR_OVF_PMI1 | P4_CCCR_ESCR_SELECT(4);
+ }

- if (!reserve_perfctr_nmi(nmi_perfctr_msr))
+ if (!reserve_perfctr_nmi(perfctr_msr))
goto fail;

- if (!reserve_evntsel_nmi(MSR_P4_CRU_ESCR0))
+ if (!reserve_evntsel_nmi(evntsel_msr))
goto fail1;

- wrmsr(MSR_P4_CRU_ESCR0, P4_NMI_CRU_ESCR0, 0);
- wrmsr(MSR_P4_IQ_CCCR0, P4_NMI_IQ_CCCR0 & ~P4_CCCR_ENABLE, 0);
- Dprintk("setting P4_IQ_COUNTER0 to 0x%08lx\n", -(cpu_khz * 1000UL / nmi_hz));
- wrmsrl(MSR_P4_IQ_COUNTER0, -((u64)cpu_khz * 1000 / nmi_hz));
+ evntsel = P4_ESCR_EVENT_SELECT(0x3F)
+ | P4_ESCR_OS
+ | P4_ESCR_USR;
+
+ cccr_val |= P4_CCCR_THRESHOLD(15)
+ | P4_CCCR_COMPLEMENT
+ | P4_CCCR_COMPARE
+ | P4_CCCR_REQUIRED;
+
+ wrmsr(evntsel_msr, evntsel, 0);
+ wrmsr(cccr_msr, cccr_val, 0);
+ wrmsrl(perfctr_msr, -((u64)cpu_khz * 1000 / nmi_hz));
apic_write(APIC_LVTPC, APIC_DM_NMI);
- wrmsr(MSR_P4_IQ_CCCR0, nmi_p4_cccr_val, 0);
+ cccr_val |= P4_CCCR_ENABLE;
+ wrmsr(cccr_msr, cccr_val, 0);
+
+ wd->perfctr_msr = perfctr_msr;
+ wd->evntsel_msr = evntsel_msr;
+ wd->cccr_msr = cccr_msr;
+ wd->check_bit = 1ULL<<39;
return 1;
fail1:
- release_perfctr_nmi(nmi_perfctr_msr);
+ release_perfctr_nmi(perfctr_msr);
fail:
return 0;
}

-void setup_apic_nmi_watchdog(void)
+static void stop_p4_watchdog(void)
{
- switch (boot_cpu_data.x86_vendor) {
- case X86_VENDOR_AMD:
- if (boot_cpu_data.x86 != 15)
- return;
- if (strstr(boot_cpu_data.x86_model_id, "Screwdriver"))
- return;
- if (!setup_k7_watchdog())
- return;
- break;
- case X86_VENDOR_INTEL:
- if (boot_cpu_data.x86 != 15)
- return;
- if (!setup_p4_watchdog())
+ struct nmi_watchdog_ctlblk *wd = &__get_cpu_var(nmi_watchdog_ctlblk);
+
+ wrmsr(wd->cccr_msr, 0, 0);
+ wrmsr(wd->evntsel_msr, 0, 0);
+
+ release_evntsel_nmi(wd->evntsel_msr);
+ release_perfctr_nmi(wd->perfctr_msr);
+}
+
+void setup_apic_nmi_watchdog(void *unused)
+{
+ /* only support LOCAL and IO APICs for now */
+ if ((nmi_watchdog != NMI_LOCAL_APIC) &&
+ (nmi_watchdog != NMI_IO_APIC))
+ return;
+
+ if (nmi_watchdog == NMI_LOCAL_APIC) {
+ switch (boot_cpu_data.x86_vendor) {
+ case X86_VENDOR_AMD:
+ if (strstr(boot_cpu_data.x86_model_id, "Screwdriver"))
+ return;
+ if (!setup_k7_watchdog())
+ return;
+ break;
+ case X86_VENDOR_INTEL:
+ if (!setup_p4_watchdog())
+ return;
+ break;
+ default:
return;
- break;
+ }
+ }
+ __get_cpu_var(nmi_watchdog_ctlblk.enabled) = 1;
+ atomic_inc(&nmi_active);
+}

- default:
- return;
+static void stop_apic_nmi_watchdog(void *unused)
+{
+ /* only support LOCAL and IO APICs for now */
+ if ((nmi_watchdog != NMI_LOCAL_APIC) &&
+ (nmi_watchdog != NMI_IO_APIC))
+ return;
+
+ if (nmi_watchdog == NMI_LOCAL_APIC) {
+ switch (boot_cpu_data.x86_vendor) {
+ case X86_VENDOR_AMD:
+ if (strstr(boot_cpu_data.x86_model_id, "Screwdriver"))
+ return;
+ stop_k7_watchdog();
+ break;
+ case X86_VENDOR_INTEL:
+ stop_p4_watchdog();
+ break;
+ default:
+ return;
+ }
}
- lapic_nmi_owner = LAPIC_NMI_WATCHDOG;
- nmi_active = 1;
+ __get_cpu_var(nmi_watchdog_ctlblk.enabled) = 0;
+ atomic_dec(&nmi_active);
}

/*
@@ -559,50 +687,70 @@ void __kprobes nmi_watchdog_tick(struct
{
int sum;
int touched = 0;
+ struct nmi_watchdog_ctlblk *wd = &__get_cpu_var(nmi_watchdog_ctlblk);
+ u64 dummy;
+
+ /* check for other users first */
+ if (notify_die(DIE_NMI, "nmi", regs, reason, 2, SIGINT)
+ == NOTIFY_STOP) {
+ touched = 1;
+ }

sum = read_pda(apic_timer_irqs);
if (__get_cpu_var(nmi_touch)) {
__get_cpu_var(nmi_touch) = 0;
touched = 1;
}
+
#ifdef CONFIG_X86_MCE
/* Could check oops_in_progress here too, but it's safer
not too */
if (atomic_read(&mce_entry) > 0)
touched = 1;
#endif
+ /* if the apic timer isn't firing, this cpu isn't doing much */
if (!touched && __get_cpu_var(last_irq_sum) == sum) {
/*
* Ayiee, looks like this CPU is stuck ...
* wait a few IRQs (5 seconds) before doing the oops ...
*/
local_inc(&__get_cpu_var(alert_counter));
- if (local_read(&__get_cpu_var(alert_counter)) == 5*nmi_hz) {
- if (notify_die(DIE_NMI, "nmi", regs, reason, 2, SIGINT)
- == NOTIFY_STOP) {
- local_set(&__get_cpu_var(alert_counter), 0);
- return;
- }
+ if (local_read(&__get_cpu_var(alert_counter)) == 5*nmi_hz)
die_nmi("NMI Watchdog detected LOCKUP on CPU %d\n", regs);
- }
} else {
__get_cpu_var(last_irq_sum) = sum;
local_set(&__get_cpu_var(alert_counter), 0);
}
- if (nmi_perfctr_msr) {
- if (nmi_perfctr_msr == MSR_P4_IQ_COUNTER0) {
- /*
- * P4 quirks:
- * - An overflown perfctr will assert its interrupt
- * until the OVF flag in its CCCR is cleared.
- * - LVTPC is masked on interrupt and must be
- * unmasked by the LVTPC handler.
- */
- wrmsr(MSR_P4_IQ_CCCR0, nmi_p4_cccr_val, 0);
- apic_write(APIC_LVTPC, APIC_DM_NMI);
- }
- wrmsrl(nmi_perfctr_msr, -((u64)cpu_khz * 1000 / nmi_hz));
+
+ /* see if the nmi watchdog went off */
+ if (wd->enabled) {
+ if (nmi_watchdog == NMI_LOCAL_APIC) {
+ rdmsrl(wd->perfctr_msr, dummy);
+ if (dummy & wd->check_bit){
+ /* this wasn't a watchdog timer interrupt */
+ goto done;
+ }
+
+ /* only Intel uses the cccr msr */
+ if (wd->cccr_msr != 0) {
+ /*
+ * P4 quirks:
+ * - An overflown perfctr will assert its interrupt
+ * until the OVF flag in its CCCR is cleared.
+ * - LVTPC is masked on interrupt and must be
+ * unmasked by the LVTPC handler.
+ */
+ rdmsrl(wd->cccr_msr, dummy);
+ dummy &= ~P4_CCCR_OVF;
+ wrmsrl(wd->cccr_msr, dummy);
+ apic_write(APIC_LVTPC, APIC_DM_NMI);
+ }
+ /* start the cycle over again */
+ wrmsrl(wd->perfctr_msr, -((u64)cpu_khz * 1000 / nmi_hz));
+ }
}
+done:
+ return;
}

static __kprobes int dummy_nmi_callback(struct pt_regs * regs, int cpu)
Index: linux-don/include/asm-x86_64/nmi.h
===================================================================
--- linux-don.orig/include/asm-x86_64/nmi.h
+++ linux-don/include/asm-x86_64/nmi.h
@@ -63,7 +63,7 @@ extern void release_perfctr_nmi(unsigned
extern int reserve_evntsel_nmi(unsigned int);
extern void release_evntsel_nmi(unsigned int);

-extern void setup_apic_nmi_watchdog (void);
+extern void setup_apic_nmi_watchdog (void *);
extern int reserve_lapic_nmi(void);
extern void release_lapic_nmi(void);
extern void disable_timer_nmi_watchdog(void);
@@ -73,6 +73,7 @@ extern void nmi_watchdog_tick (struct pt
extern void nmi_watchdog_default(void);
extern int setup_nmi_watchdog(char *);

+extern atomic_t nmi_active;
extern unsigned int nmi_watchdog;
#define NMI_DEFAULT -1
#define NMI_NONE 0

--
-
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