hw/intc/arm_gicv3_its: Implement support for in-kernel ITS emulation

The ITS control frame is in-kernel emulated while accesses to the
GITS_TRANSLATER are mediated through the KVM_SIGNAL_MSI ioctl (MSI
direct MSI injection advertised by the CAP_SIGNAL_MSI capability)

the kvm_gsi_direct_mapping is explicitly set to false to emphasize the
difference with GICv2M. Direct mapping cannot work with ITS since
the content of the MSI data is not the target interrupt ID but an
eventd id.

GSI routing is advertised (kvm_gsi_routing_allowed) as well as
msi/irqfd signaling (kvm_msi_via_irqfd_allowed).

The MSI frame (GITS_TRANSLATER) absolute GPA is computed on first
kvm_its_send_msi() call. It is then passed through KVM_SIGNAL_MSI
ioctl.

Signed-off-by: Pavel Fedin <p.fedin@samsung.com>
Signed-off-by: Eric Auger <eric.auger@redhat.com>
Message-id: 1474616617-366-6-git-send-email-eric.auger@redhat.com
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
