Avi Kivity wrote:
> Avi Kivity wrote:
>> Marcelo Tosatti wrote:
>>> On Wed, Aug 13, 2008 at 01:40:34PM +0300, Avi Kivity wrote:
>>>
>>>> Marcelo Tosatti wrote:
>>>>
>>>>> The irq ack during pic reset has three problems:
>>>>>
>>>>> - Ignores slave/master PIC, using gsi 0-8 for both.
>>>>> - Generates an ACK even if the APIC is in control.
>>>>> - Depends upon IMR being clear, which is broken if the irq was
>>>>> masked at the time it was generated.
>>>>>
>>>>> The last one causes the BIOS to hang after the first reboot of
>>>>> Windows
>>>>> installation, since PIT interrupts stop.
>>>>>
>>>>> Signed-off-by: Marcelo Tosatti <[EMAIL PROTECTED]>
>>>>>
>>>>>
>>>>> diff --git a/arch/x86/kvm/i8259.c b/arch/x86/kvm/i8259.c
>>>>> index de70499..2b42d48 100644
>>>>> --- a/arch/x86/kvm/i8259.c
>>>>> +++ b/arch/x86/kvm/i8259.c
>>>>> @@ -195,14 +195,18 @@ int kvm_pic_read_irq(struct kvm *kvm)
>>>>> void kvm_pic_reset(struct kvm_kpic_state *s)
>>>>> {
>>>>> - int irq;
>>>>> + int irq, irqbase;
>>>>> struct kvm *kvm = s->pics_state->irq_request_opaque;
>>>>> - for (irq = 0; irq < PIC_NUM_PINS; irq++) {
>>>>> - if (!(s->imr & (1 << irq)) && (s->irr & (1 << irq) ||
>>>>> - s->isr & (1 << irq)))
>>>>> - kvm_notify_acked_irq(kvm, irq);
>>>>> - }
>>>>> + if (s == &s->pics_state->pics[0])
>>>>> + irqbase = 0;
>>>>> + else
>>>>> + irqbase = 8;
>>>>> +
>>>>> + if (!kvm_lapic_enabled(kvm->vcpus[0]))
>>>>>
>>>> What if the lapic is enabled and passes through PIC interrupts in
>>>> EXTINT mode?
>>>>
>>>> btw, this will oops if we have no vcpu 0.
>>>>
>>>
>>> True. How's this:
>>> - if (!(s->imr & (1 << irq)) && (s->irr & (1 << irq) ||
>>> - s->isr & (1 << irq)))
>>> - kvm_notify_acked_irq(kvm, irq);
>>> + union ioapic_redir_entry entry;
>>> + entry = kvm->arch.vioapic->redirtbl[irq+irqbase];
>>> + if ((vcpu0 && !kvm_lapic_enabled(vcpu0)) ||
>>> + entry.fields.delivery_mode == IOAPIC_EXTINT) {
>>> + if (s->irr & (1 << irq) || s->isr & (1 << irq))
>>> + kvm_notify_acked_irq(kvm, irq+irqbase);
>>> + }
>>>
>>
>> Why look at the ioapic? You need to check lapic lvt0 delivery mode
>> for extint, not the ioapic.
>>
>
> I changed it to use kvm_apic_accept_pic_intr() and applied.
>
>
It still triggered the warning when the pit pending interrupt count
dropped below zero (booting FC6-i386). I "fixed" it by making the pit
tolerate this condition, but there may be a bigger problem lurking in there.
--
Do not meddle in the internals of kernels, for they are subtle and quick to
panic.
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