From cc6e462cd54e64858ea25816df87d033229efe56 Mon Sep 17 00:00:00 2001 From: Jan Kiszka Date: Mon, 20 Oct 2008 10:20:03 +0200 Subject: KVM: x86: Optimize NMI watchdog delivery As suggested by Avi, this patch introduces a counter of VCPUs that have LVT0 set to NMI mode. Only if the counter > 0, we push the PIT ticks via all LAPIC LVT0 lines to enable NMI watchdog support. Signed-off-by: Jan Kiszka Acked-by: Sheng Yang Signed-off-by: Avi Kivity --- arch/x86/kvm/lapic.c | 23 ++++++++++++++++++++--- 1 file changed, 20 insertions(+), 3 deletions(-) (limited to 'arch/x86/kvm/lapic.c') diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index 0b0d413f0af..afac68c0815 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -130,6 +130,11 @@ static inline int apic_lvtt_period(struct kvm_lapic *apic) return apic_get_reg(apic, APIC_LVTT) & APIC_LVT_TIMER_PERIODIC; } +static inline int apic_lvt_nmi_mode(u32 lvt_val) +{ + return (lvt_val & (APIC_MODE_MASK | APIC_LVT_MASKED)) == APIC_DM_NMI; +} + static unsigned int apic_lvt_mask[APIC_LVT_NUM] = { LVT_MASK | APIC_LVT_TIMER_PERIODIC, /* LVTT */ LVT_MASK | APIC_MODE_MASK, /* LVTTHMR */ @@ -672,6 +677,20 @@ static void start_apic_timer(struct kvm_lapic *apic) apic->timer.period))); } +static void apic_manage_nmi_watchdog(struct kvm_lapic *apic, u32 lvt0_val) +{ + int nmi_wd_enabled = apic_lvt_nmi_mode(apic_get_reg(apic, APIC_LVT0)); + + if (apic_lvt_nmi_mode(lvt0_val)) { + if (!nmi_wd_enabled) { + apic_debug("Receive NMI setting on APIC_LVT0 " + "for cpu %d\n", apic->vcpu->vcpu_id); + apic->vcpu->kvm->arch.vapics_in_nmi_mode++; + } + } else if (nmi_wd_enabled) + apic->vcpu->kvm->arch.vapics_in_nmi_mode--; +} + static void apic_mmio_write(struct kvm_io_device *this, gpa_t address, int len, const void *data) { @@ -753,9 +772,7 @@ static void apic_mmio_write(struct kvm_io_device *this, break; case APIC_LVT0: - if (val == APIC_DM_NMI) - apic_debug("Receive NMI setting on APIC_LVT0 " - "for cpu %d\n", apic->vcpu->vcpu_id); + apic_manage_nmi_watchdog(apic, val); case APIC_LVTT: case APIC_LVTTHMR: case APIC_LVTPC: -- cgit v1.2.3