hw/xen: Implement EVTCHNOP_bind_virq

Add the array of virq ports to each vCPU so that we can deliver timers,
debug ports, etc. Global virqs are allocated against vCPU 0 initially,
but can be migrated to other vCPUs (when we implement that).

The kernel needs to know about VIRQ_TIMER in order to accelerate timers,
so tell it via KVM_XEN_VCPU_ATTR_TYPE_TIMER. Also save/restore the value
of the singleshot timer across migration, as the kernel will handle the
hypercalls automatically now.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Paul Durrant <paul@xen.org>

target/i386/machine.c

@@ -1275,6 +1275,8 @@ static const VMStateDescription vmstate_xen_vcpu = {
         VMSTATE_UINT64(env.xen_vcpu_time_info_gpa, X86CPU),
         VMSTATE_UINT64(env.xen_vcpu_runstate_gpa, X86CPU),
         VMSTATE_UINT8(env.xen_vcpu_callback_vector, X86CPU),
+        VMSTATE_UINT16_ARRAY(env.xen_virq, X86CPU, XEN_NR_VIRQS),
+        VMSTATE_UINT64(env.xen_singleshot_timer_ns, X86CPU),
         VMSTATE_END_OF_LIST()
     }
 };