vhost: add support for configure interrupt

Add functions to support configure interrupt.
The configure interrupt process will start in vhost_dev_start
and stop in vhost_dev_stop.

Also add the functions to support vhost_config_pending and
vhost_config_mask, for masked_config_notifier, we only
use the notifier saved in vq 0.

Signed-off-by: Cindy Lu <lulu@redhat.com>
Message-Id: <20211104164827.21911-8-lulu@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

hw/virtio/vhost.c

@@ -1561,6 +1561,67 @@ void vhost_virtqueue_mask(struct vhost_dev *hdev, VirtIODevice *vdev, int n,
     }
 }
 
+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) {
+        VHOST_OPS_DEBUG("vhost_set_config_call failed");
+    }
+}
+
+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);
+        }
+    }
+}
+
 uint64_t vhost_get_features(struct vhost_dev *hdev, const int *feature_bits,
                             uint64_t features)
 {
@@ -1773,6 +1834,16 @@ int vhost_dev_start(struct vhost_dev *hdev, VirtIODevice *vdev)
         }
     }
 
+    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;
 
@@ -1806,6 +1877,7 @@ int vhost_dev_start(struct vhost_dev *hdev, VirtIODevice *vdev)
             vhost_device_iotlb_miss(hdev, vq->used_phys, true);
         }
     }
+    vhost_start_config_intr(hdev);
     return 0;
 fail_log:
     vhost_log_put(hdev, false);
@@ -1831,6 +1903,9 @@ void vhost_dev_stop(struct vhost_dev *hdev, VirtIODevice *vdev)
 
     /* 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);
 
     if (hdev->vhost_ops->vhost_dev_start) {
         hdev->vhost_ops->vhost_dev_start(hdev, false);
@@ -1848,6 +1923,7 @@ void vhost_dev_stop(struct vhost_dev *hdev, VirtIODevice *vdev)
         }
         memory_listener_unregister(&hdev->iommu_listener);
     }
+    vhost_stop_config_intr(hdev);
     vhost_log_put(hdev, true);
     hdev->started = false;
     hdev->vdev = NULL;

include/hw/virtio/vhost.h

@@ -29,6 +29,7 @@ struct vhost_virtqueue {
     unsigned long long used_phys;
     unsigned used_size;
     EventNotifier masked_notifier;
+    EventNotifier masked_config_notifier;
     struct vhost_dev *dev;
 };
 
@@ -37,6 +38,7 @@ 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;
@@ -116,6 +118,8 @@ int vhost_dev_start(struct vhost_dev *hdev, VirtIODevice *vdev);
 void vhost_dev_stop(struct vhost_dev *hdev, VirtIODevice *vdev);
 int vhost_dev_enable_notifiers(struct vhost_dev *hdev, VirtIODevice *vdev);
 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);
 
 /* Test and clear masked event pending status.
  * Should be called after unmask to avoid losing events.