Re: [PATCH] KVM: arm64: ITS: return 1 on successful MSI injection

Christoffer Dall
2016-08-02T13:57:40Z

On Tue, Aug 02, 2016 at 01:28:44PM +0100, Marc Zyngier wrote:
> On 02/08/16 13:23, Christoffer Dall wrote:
> > On Tue, Aug 02, 2016 at 12:10:58PM +0100, Andre Przywara wrote:
> >> According to the KVM API documentation a successful MSI injection
> >> should return a value > 0 on success.
> >> Since we pass the return value of vgic_its_inject_msi() directly on
> >> to upper layers and userland, we need to use the same semantics here.
> >> Briefly tested with QEMU and kvmtool on GICv3 hardware and the model.
> >>
> >> Signed-off-by: Andre Przywara <andre.przywara@arm.com>
> >> ---
> >> Applies on top of next-20160728. Let me know if I should use a
> >> different base.
> >>
> >> Cheers,
> >> Andre.
> >>
> >> virt/kvm/arm/vgic/vgic-its.c | 3 ++-
> >> 1 file changed, 2 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
> >> index 07411cf..3268250 100644
> >> --- a/virt/kvm/arm/vgic/vgic-its.c
> >> +++ b/virt/kvm/arm/vgic/vgic-its.c
> >> @@ -468,6 +468,7 @@ static void vgic_its_trigger_msi(struct kvm *kvm, struct vgic_its *its,
> >> * Queries the KVM IO bus framework to get the ITS pointer from the given
> >> * doorbell address.
> >> * We then call vgic_its_trigger_msi() with the decoded data.
> >> + * According to the KVM_SIGNAL_MSI API description returns > 0 on success.
> >> */
> >> int vgic_its_inject_msi(struct kvm *kvm, struct kvm_msi *msi)
> >> {
> >> @@ -493,7 +494,7 @@ int vgic_its_inject_msi(struct kvm *kvm, struct kvm_msi *msi)
> >> vgic_its_trigger_msi(kvm, iodev->its, msi->devid, msi->data);
> >> mutex_unlock(&iodev->its->its_lock);
> >>
> >> - return 0;
> >> + return 1;
> >> }
> >>
> >> /* Requires the its_lock to be held. */
> >
> > Do we have a clear understanding of what 'guest blocked the MSI'
> > constitutes in the ARM world?
>
> I would define it as "the guest has not configured the ITS so that the
> corresponding LPI could be successfully delivered". Which is any of the
> conditions where the interrupt cannot make it into the pending table,
> and is dropped on the floor.
>
sounds good to me.

-Christoffer