xen: add event channel interface for XenDevice-s

The legacy PV backend infrastructure provides functions to bind, unbind
and send notifications to event channnels. Similar functionality will be
required by XenDevice implementations so this patch adds the necessary
support.

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
---
Cc: Anthony Perard <anthony.perard@citrix.com>
v2:
 - Added error pointers to notify and unbind

diff --git a/hw/xen/xen-bus.c b/hw/xen/xen-bus.c
index faa9fd3577083def64fe25e99af996ae72e5ee0f..9443f27d4447fa11ad4e862aca6951a12dc6d219 100644 (file)
--- a/hw/xen/xen-bus.c
+++ b/hw/xen/xen-bus.c
@@ -617,6 +617,81 @@ done:
     g_free(xengnttab_segs);
 }
 
+struct XenEventChannel {
+    unsigned int local_port;
+    XenEventHandler handler;
+    void *opaque;
+    Notifier notifier;
+};
+
+static void event_notify(Notifier *n, void *data)
+{
+    XenEventChannel *channel = container_of(n, XenEventChannel, notifier);
+    unsigned long port = (unsigned long)data;
+
+    if (port == channel->local_port) {
+        channel->handler(channel->opaque);
+    }
+}
+
+XenEventChannel *xen_device_bind_event_channel(XenDevice *xendev,
+                                               unsigned int port,
+                                               XenEventHandler handler,
+                                               void *opaque, Error **errp)
+{
+    XenEventChannel *channel = g_new0(XenEventChannel, 1);
+
+    channel->local_port = xenevtchn_bind_interdomain(xendev->xeh,
+                                                     xendev->frontend_id,
+                                                     port);
+    if (xendev->local_port < 0) {
+        error_setg_errno(errp, errno, "xenevtchn_bind_interdomain failed");
+
+        g_free(channel);
+        return NULL;
+    }
+
+    channel->handler = handler;
+    channel->opaque = opaque;
+    channel->notifier.notify = event_notify;
+
+    notifier_list_add(&xendev->event_notifiers, &channel->notifier);
+
+    return channel;
+}
+
+void xen_device_notify_event_channel(XenDevice *xendev,
+                                     XenEventChannel *channel,
+                                     Error **errp)
+{
+    if (!channel) {
+        error_setg(errp, "bad channel");
+        return;
+    }
+
+    if (xenevtchn_notify(xendev->xeh, channel->local_port) < 0) {
+        error_setg_errno(errp, errno, "xenevtchn_notify failed");
+    }
+}
+
+void xen_device_unbind_event_channel(XenDevice *xendev,
+                                     XenEventChannel *channel,
+                                     Error **errp)
+{
+    if (!channel) {
+        error_setg(errp, "bad channel");
+        return;
+    }
+
+    notifier_remove(&channel->notifier);
+
+    if (xenevtchn_unbind(xendev->xeh, channel->local_port) < 0) {
+        error_setg_errno(errp, errno, "xenevtchn_unbind failed");
+    }
+
+    g_free(channel);
+}
+
 static void xen_device_unrealize(DeviceState *dev, Error **errp)
 {
     XenDevice *xendev = XEN_DEVICE(dev);
@@ -641,6 +716,12 @@ static void xen_device_unrealize(DeviceState *dev, Error **errp)
     xen_device_frontend_destroy(xendev);
     xen_device_backend_destroy(xendev);
 
+    if (xendev->xeh) {
+        qemu_set_fd_handler(xenevtchn_fd(xendev->xeh), NULL, NULL, NULL);
+        xenevtchn_close(xendev->xeh);
+        xendev->xeh = NULL;
+    }
+
     if (xendev->xgth) {
         xengnttab_close(xendev->xgth);
         xendev->xgth = NULL;
@@ -657,6 +738,16 @@ static void xen_device_exit(Notifier *n, void *data)
     xen_device_unrealize(DEVICE(xendev), &error_abort);
 }
 
+static void xen_device_event(void *opaque)
+{
+    XenDevice *xendev = opaque;
+    unsigned long port = xenevtchn_pending(xendev->xeh);
+
+    notifier_list_notify(&xendev->event_notifiers, (void *)port);
+
+    xenevtchn_unmask(xendev->xeh, port);
+}
+
 static void xen_device_realize(DeviceState *dev, Error **errp)
 {
     XenDevice *xendev = XEN_DEVICE(dev);
@@ -697,6 +788,16 @@ static void xen_device_realize(DeviceState *dev, Error **errp)
     xendev->feature_grant_copy =
         (xengnttab_grant_copy(xendev->xgth, 0, NULL) == 0);
 
+    xendev->xeh = xenevtchn_open(NULL, 0);
+    if (!xendev->xeh) {
+        error_setg_errno(errp, errno, "failed xenevtchn_open");
+        goto unrealize;
+    }
+
+    notifier_list_init(&xendev->event_notifiers);
+    qemu_set_fd_handler(xenevtchn_fd(xendev->xeh), xen_device_event, NULL,
+                        xendev);
+
     xen_device_backend_create(xendev, &local_err);
     if (local_err) {
         error_propagate(errp, local_err);

diff --git a/include/hw/xen/xen-bus.h b/include/hw/xen/xen-bus.h
index 63a09b67ee823572bad79296bd659fc7d7166167..f83a95cebdfb4e434632146086e3413b01ad113c 100644 (file)
--- a/include/hw/xen/xen-bus.h
+++ b/include/hw/xen/xen-bus.h
@@ -26,6 +26,9 @@ typedef struct XenDevice {
     XenWatch *frontend_state_watch;
     xengnttab_handle *xgth;
     bool feature_grant_copy;
+    xenevtchn_handle *xeh;
+    xenevtchn_port_or_error_t local_port;
+    NotifierList event_notifiers;
 } XenDevice;
 
 typedef char *(*XenDeviceGetName)(XenDevice *xendev, Error **errp);
@@ -104,4 +107,19 @@ void xen_device_copy_grant_refs(XenDevice *xendev, bool to_domain,
                                 XenDeviceGrantCopySegment segs[],
                                 unsigned int nr_segs, Error **errp);
 
+typedef struct XenEventChannel XenEventChannel;
+
+typedef void (*XenEventHandler)(void *opaque);
+
+XenEventChannel *xen_device_bind_event_channel(XenDevice *xendev,
+                                               unsigned int port,
+                                               XenEventHandler handler,
+                                               void *opaque, Error **errp);
+void xen_device_notify_event_channel(XenDevice *xendev,
+                                     XenEventChannel *channel,
+                                     Error **errp);
+void xen_device_unbind_event_channel(XenDevice *xendev,
+                                     XenEventChannel *channel,
+                                     Error **errp);
+
 #endif /* HW_XEN_BUS_H */