Marcelo Tosatti wrote:
The PIC code makes little effort to avoid kvm_vcpu_kick(), resulting in
unnecessary guest exits in some conditions.
For example, if the timer interrupt is routed through the IOAPIC, IRR
for IRQ 0 will get set but not cleared, since the APIC is handling the
acks.
This means that everytime an interrupt < 16 is triggered, the priority
logic will find IRQ0 pending and send an IPI to vcpu0 (in case IRQ0 is
not masked, which is Linux's case).
Introduce a new variable isr_ack to represent the IRQ's for which the
guest has been signalled / cleared the ISR. Use it to avoid more than
one IPI per trigger-ack cycle, in addition to the avoidance when ISR is
set in get_priority().
Looks good.
s->isr &= ~(1 << irq);
+ s->isr_ack |= (1 << irq);
s->isr &= ~(1 << irq);
+ s->isr_ack |= (1 << irq);
s->isr &= ~(1 << irq);
+ s->isr_ack |= (1 << irq);
s->pics_state->pics[0].isr &= ~(1 << 2);
+ s->pics_state->pics[0].isr_ack |= (1 << 2);
s->isr &= ~(1 << ret);
+ s->isr_ack |= (1 << ret);
I already have a patch which consolidates isr clearing into a function,
so I've queued it up and will push once it passes regression testing.
Please rebase your patch on top of that.
--
error compiling committee.c: too many arguments to function
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