[RFC PATCH v11bis 20/26] hw/xen: Hook up emulated implementation for event channel operations

[David Woodhouse <dwmw2@infradead.org>]

From: David Woodhouse <dwmw@amazon.co.uk>

We provided the backend-facing evtchn functions very early on as part of
the core Xen platform support, since things like timers and xenstore need
to use them.

By what may or may not be an astonishing coincidence, those functions
just *happen* all to have exactly the right function prototypes to slot
into the evtchn_backend_ops table and be called by the PV backends.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
---
 hw/i386/kvm/xen_evtchn.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/hw/i386/kvm/xen_evtchn.c b/hw/i386/kvm/xen_evtchn.c
index 3f60461e5c..4442e3ab06 100644
--- a/hw/i386/kvm/xen_evtchn.c
+++ b/hw/i386/kvm/xen_evtchn.c
@@ -34,6 +34,7 @@
 #include "hw/pci/msi.h"
 #include "hw/pci/msix.h"
 #include "hw/irq.h"
+#include "hw/xen/xen_backend_ops.h"
 
 #include "xen_evtchn.h"
 #include "xen_overlay.h"
@@ -278,6 +279,17 @@ static const TypeInfo xen_evtchn_info = {
     .class_init    = xen_evtchn_class_init,
 };
 
+static struct evtchn_backend_ops emu_evtchn_backend_ops = {
+    .open = xen_be_evtchn_open,
+    .bind_interdomain = xen_be_evtchn_bind_interdomain,
+    .unbind = xen_be_evtchn_unbind,
+    .close = xen_be_evtchn_close,
+    .get_fd = xen_be_evtchn_fd,
+    .notify = xen_be_evtchn_notify,
+    .unmask = xen_be_evtchn_unmask,
+    .pending = xen_be_evtchn_pending,
+};
+
 static void gsi_assert_bh(void *opaque)
 {
     struct vcpu_info *vi = kvm_xen_get_vcpu_info_hva(0);
@@ -318,6 +330,9 @@ void xen_evtchn_create(void)
     s->nr_pirq_inuse_words = DIV_ROUND_UP(s->nr_pirqs, 64);
     s->pirq_inuse_bitmap = g_new0(uint64_t, s->nr_pirq_inuse_words);
     s->pirq = g_new0(struct pirq_info, s->nr_pirqs);
+
+    /* Set event channel functions for backend drivers to use */
+    xen_evtchn_ops = &emu_evtchn_backend_ops;
 }
 
 void xen_evtchn_connect_gsis(qemu_irq *system_gsis)
-- 
2.39.0