[v21,07/10] vhost: add support for configure interrupt

diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
index 7fb008bc9e..84dbb39e07 100644
--- a/hw/virtio/vhost.c
+++ b/hw/virtio/vhost.c
@@ -1596,7 +1596,68 @@  void vhost_virtqueue_mask(struct vhost_dev *hdev, VirtIODevice *vdev, int n,
     file.index = hdev->vhost_ops->vhost_get_vq_index(hdev, n);
     r = hdev->vhost_ops->vhost_set_vring_call(hdev, &file);
     if (r < 0) {
-        VHOST_OPS_DEBUG(r, "vhost_set_vring_call failed");
+        error_report("vhost_set_vring_call failed %d", -r);
+    }
+}
+
+bool vhost_config_pending(struct vhost_dev *hdev)
+{
+    assert(hdev->vhost_ops);
+    if ((hdev->started == false) ||
+        (hdev->vhost_ops->vhost_set_config_call == NULL)) {
+        return false;
+    }
+
+    EventNotifier *notifier =
+        &hdev->vqs[VHOST_QUEUE_NUM_CONFIG_INR].masked_config_notifier;
+    return event_notifier_test_and_clear(notifier);
+}
+
+void vhost_config_mask(struct vhost_dev *hdev, VirtIODevice *vdev, bool mask)
+{
+    int fd;
+    int r;
+    EventNotifier *notifier =
+        &hdev->vqs[VHOST_QUEUE_NUM_CONFIG_INR].masked_config_notifier;
+    EventNotifier *config_notifier = &vdev->config_notifier;
+    assert(hdev->vhost_ops);
+
+    if ((hdev->started == false) ||
+        (hdev->vhost_ops->vhost_set_config_call == NULL)) {
+        return;
+    }
+    if (mask) {
+        assert(vdev->use_guest_notifier_mask);
+        fd = event_notifier_get_fd(notifier);
+    } else {
+        fd = event_notifier_get_fd(config_notifier);
+    }
+    r = hdev->vhost_ops->vhost_set_config_call(hdev, fd);
+    if (r < 0) {
+        error_report("vhost_set_config_call failed %d", -r);
+    }
+}
+
+static void vhost_stop_config_intr(struct vhost_dev *dev)
+{
+    int fd = -1;
+    assert(dev->vhost_ops);
+    if (dev->vhost_ops->vhost_set_config_call) {
+        dev->vhost_ops->vhost_set_config_call(dev, fd);
+    }
+}
+
+static void vhost_start_config_intr(struct vhost_dev *dev)
+{
+    int r;
+
+    assert(dev->vhost_ops);
+    int fd = event_notifier_get_fd(&dev->vdev->config_notifier);
+    if (dev->vhost_ops->vhost_set_config_call) {
+        r = dev->vhost_ops->vhost_set_config_call(dev, fd);
+        if (!r) {
+            event_notifier_set(&dev->vdev->config_notifier);
+        }
     }
 }
 
@@ -1836,6 +1897,16 @@  int vhost_dev_start(struct vhost_dev *hdev, VirtIODevice *vdev, bool vrings)
         }
     }
 
+    r = event_notifier_init(
+        &hdev->vqs[VHOST_QUEUE_NUM_CONFIG_INR].masked_config_notifier, 0);
+    if (r < 0) {
+        return r;
+    }
+    event_notifier_test_and_clear(
+        &hdev->vqs[VHOST_QUEUE_NUM_CONFIG_INR].masked_config_notifier);
+    if (!vdev->use_guest_notifier_mask) {
+        vhost_config_mask(hdev, vdev, true);
+    }
     if (hdev->log_enabled) {
         uint64_t log_base;
 
@@ -1874,6 +1945,7 @@  int vhost_dev_start(struct vhost_dev *hdev, VirtIODevice *vdev, bool vrings)
             vhost_device_iotlb_miss(hdev, vq->used_phys, true);
         }
     }
+    vhost_start_config_intr(hdev);
     return 0;
 fail_start:
     if (vrings) {
@@ -1903,6 +1975,9 @@  void vhost_dev_stop(struct vhost_dev *hdev, VirtIODevice *vdev, bool vrings)
 
     /* should only be called after backend is connected */
     assert(hdev->vhost_ops);
+    event_notifier_test_and_clear(
+        &hdev->vqs[VHOST_QUEUE_NUM_CONFIG_INR].masked_config_notifier);
+    event_notifier_test_and_clear(&vdev->config_notifier);
 
     trace_vhost_dev_stop(hdev, vdev->name, vrings);
 
@@ -1925,6 +2000,7 @@  void vhost_dev_stop(struct vhost_dev *hdev, VirtIODevice *vdev, bool vrings)
         }
         memory_listener_unregister(&hdev->iommu_listener);
     }
+    vhost_stop_config_intr(hdev);
     vhost_log_put(hdev, true);
     hdev->started = false;
     vdev->vhost_started = false;
diff --git a/include/hw/virtio/vhost.h b/include/hw/virtio/vhost.h
index 67a6807fac..05bedb2416 100644
--- a/include/hw/virtio/vhost.h
+++ b/include/hw/virtio/vhost.h
@@ -33,6 +33,7 @@  struct vhost_virtqueue {
     unsigned used_size;
     EventNotifier masked_notifier;
     EventNotifier error_notifier;
+    EventNotifier masked_config_notifier;
     struct vhost_dev *dev;
 };
 
@@ -41,6 +42,7 @@  typedef unsigned long vhost_log_chunk_t;
 #define VHOST_LOG_BITS (8 * sizeof(vhost_log_chunk_t))
 #define VHOST_LOG_CHUNK (VHOST_LOG_PAGE * VHOST_LOG_BITS)
 #define VHOST_INVALID_FEATURE_BIT   (0xff)
+#define VHOST_QUEUE_NUM_CONFIG_INR 0
 
 struct vhost_log {
     unsigned long long size;
@@ -168,6 +170,8 @@  int vhost_dev_enable_notifiers(struct vhost_dev *hdev, VirtIODevice *vdev);
  * Disable direct notifications to vhost device.
  */
 void vhost_dev_disable_notifiers(struct vhost_dev *hdev, VirtIODevice *vdev);
+bool vhost_config_pending(struct vhost_dev *hdev);
+void vhost_config_mask(struct vhost_dev *hdev, VirtIODevice *vdev, bool mask);
 
 /**
  * vhost_dev_is_started() - report status of vhost device