Re: [PATCH v3 1/8] Do not call ack notifiers on PIC reset.

[Marcelo Tosatti <mtosatti@redhat.com>]

On Wed, Aug 12, 2009 at 03:17:15PM +0300, Gleb Natapov wrote:
> For device assigned it may cause host hang since ack notifier callback
> enables host interrupt and guest not necessary cleared interrupt
> condition in an assigned device. For PIT we should not call ack notifier
> here since interrupt was not acked by a guest and should be redelivered.
> 
> Signed-off-by: Gleb Natapov <gleb@redhat.com>
> ---
>  arch/x86/kvm/i8259.c |   16 ----------------
>  1 files changed, 0 insertions(+), 16 deletions(-)
> 
> diff --git a/arch/x86/kvm/i8259.c b/arch/x86/kvm/i8259.c
> index 01f1516..eb2b8b7 100644
> --- a/arch/x86/kvm/i8259.c
> +++ b/arch/x86/kvm/i8259.c
> @@ -225,22 +225,6 @@ int kvm_pic_read_irq(struct kvm *kvm)
>  
>  void kvm_pic_reset(struct kvm_kpic_state *s)
>  {
> -	int irq, irqbase, n;
> -	struct kvm *kvm = s->pics_state->irq_request_opaque;
> -	struct kvm_vcpu *vcpu0 = kvm->bsp_vcpu;
> -
> -	if (s == &s->pics_state->pics[0])
> -		irqbase = 0;
> -	else
> -		irqbase = 8;
> -
> -	for (irq = 0; irq < PIC_NUM_PINS/2; irq++) {
> -		if (vcpu0 && kvm_apic_accept_pic_intr(vcpu0))
> -			if (s->irr & (1 << irq) || s->isr & (1 << irq)) {
> -				n = irq + irqbase;
> -				kvm_notify_acked_irq(kvm, SELECT_PIC(n), n);
> -			}
> -	}
>  	s->last_irr = 0;
>  	s->irr = 0;
>  	s->imr = 0;
> -- 
> 1.6.3.3

This used to be necessary to clear pending state from i8254.c
"irq_acked" logic. I think it'll break it.