Re: [PATCH] KVM: PIC: call ack notifiers for irqs that are dropped form irr

[Marcelo Tosatti <mtosatti@redhat.com>]

On Tue, Jul 17, 2012 at 02:59:11PM +0300, Gleb Natapov wrote:
> After commit 242ec97c358256 PIT interrupts are no longer delivered after
> PIC reset. It happens because PIT injects interrupt only if previous one
> was acked, but since on PIC reset it is dropped from irr it will never
> be delivered and hence acknowledged. Fix that by calling ack notifier on
> PIC reset.
> 
> Signed-off-by: Gleb Natapov <gleb@redhat.com>
> diff --git a/arch/x86/kvm/i8259.c b/arch/x86/kvm/i8259.c
> index 81cf4fa..f09e790 100644
> --- a/arch/x86/kvm/i8259.c
> +++ b/arch/x86/kvm/i8259.c
> @@ -305,6 +305,7 @@ static void pic_ioport_write(void *opaque, u32 addr, u32 val)
>  	addr &= 1;
>  	if (addr == 0) {
>  		if (val & 0x10) {
> +			u8 edge_irr = s->irr & ~s->elcr;
>  			s->init4 = val & 1;
>  			s->last_irr = 0;
>  			s->irr &= s->elcr;
> @@ -322,6 +323,9 @@ static void pic_ioport_write(void *opaque, u32 addr, u32 val)
>  			if (val & 0x08)
>  				pr_pic_unimpl(
>  					"level sensitive irq not supported");
> +			for (irq = 0; irq < PIC_NUM_PINS/2; irq++)
> +				if (edge_irr & (1 << irq))
> +					pic_clear_isr(s, irq);
>  		} else if (val & 0x08) {
>  			if (val & 0x04)
>  				s->poll = 1;
> --
> 			Gleb.

Can modify kvm_pic_reset (currently unused BTW) to conform to
9ed049c3b6230b6898 ? It checks for APIC handling interrupts
before acking.