On 20/01/2015 09:48, Wincy Van wrote:
> +static int vmx_deliver_nested_posted_interrupt(struct kvm_vcpu *vcpu,
> + int vector)
> +{
> + int r = 0;
> + struct vmcs12 *vmcs12;
> +
> + /*
> + * Since posted intr delivery is async,
> + * we must aquire a spin-lock to avoid
> + * the race of vmcs12.
> + */
> + spin_lock(&to_vmx(vcpu)->nested.vmcs12_lock);
> + vmcs12 = get_vmcs12(vcpu);
> + if (!is_guest_mode(vcpu) || !vmcs12) {
> + r = -1;
> + goto out;
> + }
is_guest_mode should be checked first outside the lock, to avoid
affecting the non-nested fast path. You can then recheck it later
inside the lock.
Another way to avoid the spinlock: in prepare_vmcs02 or a similar place,
you can save vmcs12->posted_intr_nv in a new field
vmx->nested.posted_intr_nv; just set it to -1 if
!nested_cpu_has_posted_intr(vmcs12). In vmclear, again you just set the
field to -1, and here you can do
if (!is_guest_mode(vcpu) ||
vector != to_vmx(vcpu)->nested.posted_intr_nv) {
r = -1;
goto out;
}
You don't need to access vmcs12, and while there is a race, it's okay
because there is no pointer access.
>
> + if (vcpu->mode == IN_GUEST_MODE)
> + apic->send_IPI_mask(get_cpu_mask(vcpu->cpu),
> + POSTED_INTR_VECTOR);
Please add a comment that PIR and ON have been set by the L1 hypervisor.
I'll do a full review the other patches as soon as possible.
Paolo
> + else {
> + r = -1;
> + goto out;
> + }
> +
> + /*
> + * if posted intr is done by hardware, the
> + * corresponding eoi was sent to L0. Thus
> + * we should send eoi to L1 manually.
> + */
> + kvm_apic_set_eoi_accelerated(vcpu,
> + vmcs12->posted_intr_nv);
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