Re: [PATCH 5/9] kvm-x86: Enable NMI Watchdog via in-kernel PIT source

["Yang, Sheng" <sheng.yang@intel.com>]

On Friday 19 September 2008 20:03:02 Jan Kiszka wrote:
> LINT0 of the LAPIC can be used to route PIT events as NMI watchdog
> ticks into the guest. This patch aligns the in-kernel irqchip emulation
> with the user space irqchip with already supports this feature. The
> trick is to route PIT interrupts to all LAPIC's LVT0 lines.
>
> Rebased patch and slightly polished patch originally posted by Sheng
> Yang.

Signed-off-by: Sheng Yang <sheng.yang@intel.com>

Thanks for pick up this patch again! 

Have you test some Windows guest with this watchdog? Last time I dropped it 
because it cause BSOD on some version of Windows(IRQ_NOT_EQUAL_OR_LESS). I 
don't remember the exactly situation there, but you may have a try. 

-- 
regards
Yang, Sheng
>
> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
> ---
>  arch/x86/kvm/i8254.c |   15 +++++++++++++++
>  arch/x86/kvm/irq.h   |    1 +
>  arch/x86/kvm/lapic.c |   32 ++++++++++++++++++++++++++++----
>  3 files changed, 44 insertions(+), 4 deletions(-)
>
> Index: b/arch/x86/kvm/i8254.c
> ===================================================================
> --- a/arch/x86/kvm/i8254.c
> +++ b/arch/x86/kvm/i8254.c
> @@ -594,10 +594,25 @@ void kvm_free_pit(struct kvm *kvm)
>
>  static void __inject_pit_timer_intr(struct kvm *kvm)
>  {
> +       struct kvm_vcpu *vcpu;
> +       int i;
> +
>         mutex_lock(&kvm->lock);
>         kvm_set_irq(kvm, 0, 1);
>         kvm_set_irq(kvm, 0, 0);
>         mutex_unlock(&kvm->lock);
> +
> +       /*
> +        * Provideds NMI watchdog support in IOAPIC mode.
> +        * The route is: PIT -> PIC -> LVT0 in NMI mode,
> +        * timer IRQs will continue to flow through the IOAPIC.
> +        */
> +       for (i = 0; i < KVM_MAX_VCPUS; ++i) {
> +               vcpu = kvm->vcpus[i];
> +               if (!vcpu)
> +                       continue;
> +               kvm_apic_local_deliver(vcpu, APIC_LVT0);
> +       }
>  }
>
>  void kvm_inject_pit_timer_irqs(struct kvm_vcpu *vcpu)
> Index: b/arch/x86/kvm/irq.h
> ===================================================================
> --- a/arch/x86/kvm/irq.h
> +++ b/arch/x86/kvm/irq.h
> @@ -93,6 +93,7 @@ void kvm_unregister_irq_ack_notifier(str
>  void kvm_timer_intr_post(struct kvm_vcpu *vcpu, int vec);
>  void kvm_inject_pending_timer_irqs(struct kvm_vcpu *vcpu);
>  void kvm_inject_apic_timer_irqs(struct kvm_vcpu *vcpu);
> +int kvm_apic_local_deliver(struct kvm_vcpu *vcpu, int lvt_type);
>  void __kvm_migrate_apic_timer(struct kvm_vcpu *vcpu);
>  void __kvm_migrate_pit_timer(struct kvm_vcpu *vcpu);
>  void __kvm_migrate_timers(struct kvm_vcpu *vcpu);
> Index: b/arch/x86/kvm/lapic.c
> ===================================================================
> --- a/arch/x86/kvm/lapic.c
> +++ b/arch/x86/kvm/lapic.c
> @@ -382,6 +382,14 @@ static int __apic_accept_irq(struct kvm_
>                 }
>                 break;
>
> +       case APIC_DM_EXTINT:
> +               /*
> +                * Should only be called by kvm_apic_local_deliver() with
> LVT0, +                * before NMI watchdog was enabled. Already handled
> by +                * kvm_apic_accept_pic_intr().
> +                */
> +               break;
> +
>         default:
>                 printk(KERN_ERR "TODO: unsupported delivery mode %x\n",
>                        delivery_mode);
> @@ -749,6 +757,9 @@ static void apic_mmio_write(struct kvm_i
>         case APIC_LVTTHMR:
>         case APIC_LVTPC:
>         case APIC_LVT0:
> +               if (val == APIC_DM_NMI)
> +                       apic_debug("Receive NMI setting on APIC_LVT0 "
> +                               "for cpu %d\n", apic->vcpu->vcpu_id);
>         case APIC_LVT1:
>         case APIC_LVTERR:
>                 /* TODO: Check vector */
> @@ -965,12 +976,25 @@ int apic_has_pending_timer(struct kvm_vc
>         return 0;
>  }
>
> -static int __inject_apic_timer_irq(struct kvm_lapic *apic)
> +int kvm_apic_local_deliver(struct kvm_vcpu *vcpu, int lvt_type)
>  {
> -       int vector;
> +       struct kvm_lapic *apic = vcpu->arch.apic;
> +       int vector, mode, trig_mode;
> +       u32 reg;
> +
> +       if (apic && apic_enabled(apic)) {
> +               reg = apic_get_reg(apic, lvt_type);
> +               vector = reg & APIC_VECTOR_MASK;
> +               mode = reg & APIC_MODE_MASK;
> +               trig_mode = reg & APIC_LVT_LEVEL_TRIGGER;
> +               return __apic_accept_irq(apic, mode, vector, 1, trig_mode);
> +       }
> +       return 0;
> +}
>
> -       vector = apic_lvt_vector(apic, APIC_LVTT);
> -       return __apic_accept_irq(apic, APIC_DM_FIXED, vector, 1, 0);
> +static inline int __inject_apic_timer_irq(struct kvm_lapic *apic)
> +{
> +       return kvm_apic_local_deliver(apic->vcpu, APIC_LVTT);
>  }
>
>  static enum hrtimer_restart apic_timer_fn(struct hrtimer *data)