[Qemu-devel] [PATCH uq/master 8/9] virtio: move common ioeventfd handling out of virtio-pci

[Paolo Bonzini <pbonzini@redhat.com>]

All transports can use the same event handler for the ioeventfd, though
the exact setup (address/memory region) will be specific.

This lets virtio use event_notifier_set_handler.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 hw/virtio-pci.c |   36 ++----------------------------------
 hw/virtio.c     |   22 ++++++++++++++++++++++
 hw/virtio.h     |    1 +
 3 files changed, 25 insertions(+), 34 deletions(-)

diff --git a/hw/virtio-pci.c b/hw/virtio-pci.c
index a555728..36770fd 100644
--- a/hw/virtio-pci.c
+++ b/hw/virtio-pci.c
@@ -173,46 +173,18 @@ static int virtio_pci_set_host_notifier_internal(VirtIOPCIProxy *proxy,
                          __func__, r);
             return r;
         }
+        virtio_queue_set_host_notifier_fd_handler(vq, true);
         memory_region_add_eventfd(&proxy->bar, VIRTIO_PCI_QUEUE_NOTIFY, 2,
                                   true, n, notifier);
     } else {
         memory_region_del_eventfd(&proxy->bar, VIRTIO_PCI_QUEUE_NOTIFY, 2,
                                   true, n, notifier);
-        /* Handle the race condition where the guest kicked and we deassigned
-         * before we got around to handling the kick.
-         */
-        if (event_notifier_test_and_clear(notifier)) {
-            virtio_queue_notify_vq(vq);
-        }
-
+        virtio_queue_set_host_notifier_fd_handler(vq, false);
         event_notifier_cleanup(notifier);
     }
     return r;
 }
 
-static void virtio_pci_host_notifier_read(void *opaque)
-{
-    VirtQueue *vq = opaque;
-    EventNotifier *n = virtio_queue_get_host_notifier(vq);
-    if (event_notifier_test_and_clear(n)) {
-        virtio_queue_notify_vq(vq);
-    }
-}
-
-static void virtio_pci_set_host_notifier_fd_handler(VirtIOPCIProxy *proxy,
-                                                    int n, bool assign)
-{
-    VirtQueue *vq = virtio_get_queue(proxy->vdev, n);
-    EventNotifier *notifier = virtio_queue_get_host_notifier(vq);
-    if (assign) {
-        qemu_set_fd_handler(event_notifier_get_fd(notifier),
-                            virtio_pci_host_notifier_read, NULL, vq);
-    } else {
-        qemu_set_fd_handler(event_notifier_get_fd(notifier),
-                            NULL, NULL, NULL);
-    }
-}
-
 static void virtio_pci_start_ioeventfd(VirtIOPCIProxy *proxy)
 {
     int n, r;
@@ -232,8 +204,6 @@ static void virtio_pci_start_ioeventfd(VirtIOPCIProxy *proxy)
         if (r < 0) {
             goto assign_error;
         }
-
-        virtio_pci_set_host_notifier_fd_handler(proxy, n, true);
     }
     proxy->ioeventfd_started = true;
     return;
@@ -244,7 +214,6 @@ assign_error:
             continue;
         }
 
-        virtio_pci_set_host_notifier_fd_handler(proxy, n, false);
         r = virtio_pci_set_host_notifier_internal(proxy, n, false);
         assert(r >= 0);
     }
@@ -266,7 +235,6 @@ static void virtio_pci_stop_ioeventfd(VirtIOPCIProxy *proxy)
             continue;
         }
 
-        virtio_pci_set_host_notifier_fd_handler(proxy, n, false);
         r = virtio_pci_set_host_notifier_internal(proxy, n, false);
         assert(r >= 0);
     }
diff --git a/hw/virtio.c b/hw/virtio.c
index 168abe4..197edf0 100644
--- a/hw/virtio.c
+++ b/hw/virtio.c
@@ -988,6 +988,28 @@ EventNotifier *virtio_queue_get_guest_notifier(VirtQueue *vq)
 {
     return &vq->guest_notifier;
 }
+
+static void virtio_queue_host_notifier_read(EventNotifier *n)
+{
+    VirtQueue *vq = container_of(n, VirtQueue, host_notifier);
+    if (event_notifier_test_and_clear(n)) {
+        virtio_queue_notify_vq(vq);
+    }
+}
+
+void virtio_queue_set_host_notifier_fd_handler(VirtQueue *vq, bool assign)
+{
+    if (assign) {
+        event_notifier_set_handler(&vq->host_notifier,
+                                   virtio_queue_host_notifier_read);
+    } else {
+        event_notifier_set_handler(&vq->host_notifier, NULL);
+        /* Test and clear notifier before after disabling event,
+         * in case poll callback didn't have time to run. */
+        virtio_queue_host_notifier_read(&vq->host_notifier);
+    }
+}
+
 EventNotifier *virtio_queue_get_host_notifier(VirtQueue *vq)
 {
     return &vq->host_notifier;
diff --git a/hw/virtio.h b/hw/virtio.h
index 85aabe5..2949485 100644
--- a/hw/virtio.h
+++ b/hw/virtio.h
@@ -232,6 +232,7 @@ VirtQueue *virtio_get_queue(VirtIODevice *vdev, int n);
 int virtio_queue_get_id(VirtQueue *vq);
 EventNotifier *virtio_queue_get_guest_notifier(VirtQueue *vq);
 EventNotifier *virtio_queue_get_host_notifier(VirtQueue *vq);
+void virtio_queue_set_host_notifier_fd_handler(VirtQueue *vq, bool assign);
 void virtio_queue_notify_vq(VirtQueue *vq);
 void virtio_irq(VirtQueue *vq);
 #endif
-- 
1.7.10.2