On 28/07/2015 21:06, Steve Rutherford wrote:
>>> > > + if (!kvm_run->ready_for_interrupt_injection &&
>>> > > + ready_for_interrupt_injection)
>>> > > + kvm_make_request(KVM_REQ_PIC_UNMASK_EXIT, vcpu);
>>> > > +
>>> > > + kvm_run->ready_for_interrupt_injection =
>>> > > + ready_for_interrupt_injection;
>>> > > + } else {
>>> > > kvm_run->ready_for_interrupt_injection =
>>> > > kvm_arch_interrupt_allowed(vcpu) &&
>>> > > !kvm_cpu_has_interrupt(vcpu) &&
>>> > > !kvm_event_needs_reinjection(vcpu);
>>> > > + }
>>> > > }
>>> > >
>>> > > static void update_cr8_intercept(struct kvm_vcpu *vcpu)
>> >
>> > Why is this necessary? Could it just set
>> > kvm_run->ready_for_interrupt_injection as in the pic_in_kernel case?
> The goal is to couple the interrupt ack cycle as closely as possible
> with the injection of the local interrupt (which occur more or less
> atomically on real hardware). The idea is to only ever attempt to
> inject local interrupts when the CPU/APIC is ready to immediately
> accept.
Ok, I understand it now. However, you're still not causing an exit
when LVT0 changes, are you? post_kvm_run_save is not run until the
next exit to userspace, which could be a long time later.
So, I think that you do not need KVM_REQ_PIC_UNMASK_EXIT. Instead,
you can modify dm_request_for_irq_injection to handle the split-irqchip
case, like this:
if (!vcpu->run->request_interrupt_window || pic_in_kernel(vcpu->kvm))
return false;
if (kvm_cpu_has_interrupt(vcpu))
return false;
return (irqchip_split(vcpu->kvm)
? kvm_apic_accept_pic_intr(vcpu)
: kvm_arch_interrupt_allowed(vcpu));
This will cause KVM_RUN to return -EINTR, which QEMU happens to handle
the same way as KVM_EXIT_IRQ_WINDOW_OPEN. If you prefer the explicit
reason, this small change will provide it:
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 5ef2560075bf..3269169233fb 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6720,8 +6720,8 @@ static int vcpu_run(struct kvm_vcpu *vcpu)
kvm_inject_pending_timer_irqs(vcpu);
if (dm_request_for_irq_injection(vcpu)) {
- r = -EINTR;
- vcpu->run->exit_reason = KVM_EXIT_INTR;
+ r = 0;
+ vcpu->run->exit_reason = KVM_EXIT_IRQ_WINDOW_OPEN;
++vcpu->stat.request_irq_exits;
break;
}
Feel free to post v6 of this patch only. Everything else is mostly
okay; there are some leftovers here and there (lapic_in_kernel,
GET_VECTOR_FROM_USERSPACE) but I can fix that.
How is the integration with QEMU going? With this latest iteration
it should be relatively easy.
Paolo
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