On Wed, Jul 28, 2010 at 07:53:32PM +0300, Avi Kivity wrote:
> On 07/28/2010 07:37 PM, Marcelo Tosatti wrote:
> >On Wed, Jul 28, 2010 at 07:31:03PM +0300, Avi Kivity wrote:
> >> On 07/28/2010 07:21 PM, Marcelo Tosatti wrote:
> >>>On Tue, Jul 27, 2010 at 04:19:35PM +0300, Avi Kivity wrote:
> >>>>Instead of blindly attempting to inject an event before each guest entry,
> >>>>check for a possible event first in vcpu->requests. Sites that can trigger
> >>>>event injection are modified to set KVM_REQ_EVENT:
> >>>>
> >>>>- interrupt, nmi window opening
> >>>>- ppr updates
> >>>>- i8259 output changes
> >>>>- local apic irr changes
> >>>>- rflags updates
> >>>>- gif flag set
> >>>>- event set on exit
> >>>>
> >>>>This improves non-injecting entry performance, and sets the stage for
> >>>>non-atomic injection.
> >>>>
> >>>>Signed-off-by: Avi Kivity<avi@xxxxxxxxxx>
> >>>>---
> >>>> arch/x86/kvm/i8259.c | 1 +
> >>>> arch/x86/kvm/lapic.c | 12 ++++++++++--
> >>>> arch/x86/kvm/svm.c | 8 +++++++-
> >>>> arch/x86/kvm/vmx.c | 6 ++++++
> >>>> arch/x86/kvm/x86.c | 35 ++++++++++++++++++++++++++---------
> >>>> include/linux/kvm_host.h | 1 +
> >>>> 6 files changed, 51 insertions(+), 12 deletions(-)
> >>>>
> >>>>@@ -4731,17 +4737,19 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
> >>>> goto out;
> >>>> }
> >>>>
> >>>>- inject_pending_event(vcpu);
> >>>>+ if (kvm_check_request(KVM_REQ_EVENT, vcpu)) {
> >>>>+ inject_pending_event(vcpu);
> >>>>
> >>>>- /* enable NMI/IRQ window open exits if needed */
> >>>>- if (vcpu->arch.nmi_pending)
> >>>>- kvm_x86_ops->enable_nmi_window(vcpu);
> >>>>- else if (kvm_cpu_has_interrupt(vcpu) || req_int_win)
> >>>>- kvm_x86_ops->enable_irq_window(vcpu);
> >>>>+ /* enable NMI/IRQ window open exits if needed */
> >>>>+ if (vcpu->arch.nmi_pending)
> >>>>+ kvm_x86_ops->enable_nmi_window(vcpu);
> >>>>+ else if (kvm_cpu_has_interrupt(vcpu) || req_int_win)
> >>>>+ kvm_x86_ops->enable_irq_window(vcpu);
> >>>Problem is it might not be possible to inject the event signalled by
> >>>KVM_REQ_EVENT, say an interrupt from an irqchip, if there is an event
> >>>that needs reinjection (or an exception).
> >>That can happen event now, no? A pending exception, interrupt comes
> >>along, injection picks up the exception but leaves the interrupt.
> >>
> >>Now the situation can be more complicated:
> >>
> >>- pending exception
> >>- injection
> >>- interrupt, sets KVM_REQ_EVENT
> >>- notices KVM_REQ_EVENT
> >>- drops KVM_REQ_EVENT, cancels exception (made pending again)
> >>- goes back
> >>- injection (injects exception again, interrupt is pending)
> >>
> >>as far as I can tell, this is all fine.
> >But you cleared KVM_REQ_EVENT. Which means you're not going to inject
> >the pending interrupt on the next entry.
>
> Doh. So we need to set KVM_REQ_EVENT again, after the final check
> for vcpu->requests, to make sure we redo injection again.
>
> So we can make inject_pending_event() return true if there's more in
> the queue, and if it did, re-raise KVM_REQ_EVENT just before entry?
Yeah, that would do it.
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