vhost: add vhost_get_features and vhost_ack_features

Generalize the features get/ack to be used for both vhost-net and vhost-scsi.
In vhost-net add vhost_net_get_feature_bits to select the feature bit set
depending on the NetClient kind.

Signed-off-by: Nikolay Nikolaev <n.nikolaev@virtualopensystems.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

1 files changed, 27 insertions, 0 deletions

diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
index 9e6023a..a3e872d 100644
--- a/hw/virtio/vhost.c
+++ b/hw/virtio/vhost.c
@@ -990,6 +990,33 @@ void vhost_virtqueue_mask(struct vhost_dev *hdev, VirtIODevice *vdev, int n,
     assert(r >= 0);
 }
 
+unsigned vhost_get_features(struct vhost_dev *hdev, const int *feature_bits,
+        unsigned features)
+{
+    const int *bit = feature_bits;
+    while (*bit != VHOST_INVALID_FEATURE_BIT) {
+        unsigned bit_mask = (1 << *bit);
+        if (!(hdev->features & bit_mask)) {
+            features &= ~bit_mask;
+        }
+        bit++;
+    }
+    return features;
+}
+
+void vhost_ack_features(struct vhost_dev *hdev, const int *feature_bits,
+        unsigned features)
+{
+    const int *bit = feature_bits;
+    while (*bit != VHOST_INVALID_FEATURE_BIT) {
+        unsigned bit_mask = (1 << *bit);
+        if (features & bit_mask) {
+            hdev->acked_features |= bit_mask;
+        }
+        bit++;
+    }
+}
+
 /* Host notifiers must be enabled at this point. */
 int vhost_dev_start(struct vhost_dev *hdev, VirtIODevice *vdev)
 {