From mboxrd@z Thu Jan  1 00:00:00 1970
From: Gleb Natapov <gleb@redhat.com>
Subject: Re: [PATCH] KVM: PIC: call ack notifiers for irqs that are dropped
 form irr
Date: Fri, 20 Jul 2012 16:20:47 +0300
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References: <20120717115910.GG6345@redhat.com>
 <20120720115856.GC9832@amt.cnet>
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To: Marcelo Tosatti <mtosatti@redhat.com>
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On Fri, Jul 20, 2012 at 08:58:56AM -0300, Marcelo Tosatti wrote:
> 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.
Since it is not used we can make it do anything. But preferably in
speared patch otherwise bug fix will be obfuscated by code move.

--
			Gleb.