From a56fe63c12a3c9e77995a3707d3165f817acd4af Mon Sep 17 00:00:00 2001 From: Tim Deegan Date: Tue, 28 Jun 2011 09:16:13 +0100 Subject: [PATCH] x86: fix boot-time watchdog test. Since the perf counter that the LAPIC NMI watchdog uses only runs while the core isn't halted, and all APs are idle at this point in the boot process, it's possible that remote CPUs won't see any NMIs during the 10-tick waiting period. Force all CPUs to busy-wait so we know the timers are running. Signed-off-by: Tim Deegan --- xen/arch/x86/nmi.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/xen/arch/x86/nmi.c b/xen/arch/x86/nmi.c index 6730f29a0a..2fd864e868 100644 --- a/xen/arch/x86/nmi.c +++ b/xen/arch/x86/nmi.c @@ -95,6 +95,11 @@ int nmi_active; (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) +static void __init wait_for_nmis(void *p) +{ + mdelay((10*1000)/nmi_hz); /* wait 10 ticks */ +} + int __init check_nmi_watchdog (void) { static unsigned int __initdata prev_nmi_count[NR_CPUS]; @@ -108,7 +113,12 @@ int __init check_nmi_watchdog (void) for_each_online_cpu ( cpu ) prev_nmi_count[cpu] = nmi_count(cpu); local_irq_enable(); - mdelay((10*1000)/nmi_hz); /* wait 10 ticks */ + + /* Wait for 10 ticks. Busy-wait on all CPUs: the LAPIC counter that + * the NMI watchdog uses only runs while the core's not halted */ + if ( nmi_watchdog == NMI_LOCAL_APIC ) + smp_call_function(wait_for_nmis, NULL, 0); + wait_for_nmis(NULL); for_each_online_cpu ( cpu ) { -- 2.30.2