On Mon, Jun 14, 2010, Avi Kivity wrote about "Re: [PATCH 20/24] Correct
handling of interrupt injection":
>..
> >However, properly doing what is described above requires invasive changes
> >to
> >the flow of the existing code, which we elected not to do in this stage.
> >Instead we do something more simplistic and less efficient: we modify
>...
>
> That's a little sad.
I agree. I'd like to change this code to do the proper thing (as I explained
in the patch's description), but as I said this will require some invasive
changes to existing KVM code outside vmx.c.
So seeing that this existing code also works, and despite hurting performance
a bit there are much more pressing performance issues (namely, the need
for nested EPT) - with your permission I'd like to postpone fixing this issue.
> > static int vmx_interrupt_allowed(struct kvm_vcpu *vcpu)
> > {
> >+ if (to_vmx(vcpu)->nested.nested_mode&& nested_exit_on_intr(vcpu)) {
> >+ if (to_vmx(vcpu)->nested.nested_run_pending)
> >+ return 0;
> >+ nested_vmx_vmexit(vcpu, true);
> >+ /* fall through to normal code, but now in L1, not L2 */
> >+ }
> >+
> >
>
> What exit is reported here?
When nested_vmx_vmexit is called with the second parameter true, as above,
it modifies the (vmcs12) exit reason to be EXIT_REASON_EXTERNAL_INTERRUPT.
A hack, but it does the right thing in this case because L1 doesn't even get
a chance to care about this exit reason before it exits again (as I tried to
explain in the patch's description).
--
Nadav Har'El | Thursday, Sep 16 2010, 8 Tishri 5771
[email protected] |-----------------------------------------
Phone +972-523-790466, ICQ 13349191 |Debugging: the art of removing bugs.
http://nadav.harel.org.il |Programming: the art of inserting them.
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