Fix networking problem after r280026.

I've missed that network driver sometimes returns taken request back to
available queue without processing.  Add new helper function for that case.

Reported by:	flo
MFC after:	2 weeks

3 files changed, 17 insertions, 2 deletions

diff --git a/usr.sbin/bhyve/pci_virtio_net.c b/usr.sbin/bhyve/pci_virtio_net.c
index 8232b07..f3656b7 100644
--- a/usr.sbin/bhyve/pci_virtio_net.c
+++ b/usr.sbin/bhyve/pci_virtio_net.c
@@ -342,6 +342,7 @@ pci_vtnet_tap_rx(struct pci_vtnet_softc *sc)
 			 * No more packets, but still some avail ring
 			 * entries.  Interrupt if needed/appropriate.
 			 */
+			vq_retchain(vq);
 			vq_endchains(vq, 0);
 			return;
 		}
diff --git a/usr.sbin/bhyve/virtio.c b/usr.sbin/bhyve/virtio.c
index 0a750ce..e985805 100644
--- a/usr.sbin/bhyve/virtio.c
+++ b/usr.sbin/bhyve/virtio.c
@@ -372,8 +372,21 @@ loopy:
 }
 
 /*
- * Return the currently-first request chain to the guest, setting
- * its I/O length to the provided value.
+ * Return the currently-first request chain back to the available queue.
+ *
+ * (This chain is the one you handled when you called vq_getchain()
+ * and used its positive return value.)
+ */
+void
+vq_retchain(struct vqueue_info *vq)
+{
+
+	vq->vq_last_avail--;
+}
+
+/*
+ * Return specified request chain to the guest, setting its I/O length
+ * to the provided value.
  *
  * (This chain is the one you handled when you called vq_getchain()
  * and used its positive return value.)
diff --git a/usr.sbin/bhyve/virtio.h b/usr.sbin/bhyve/virtio.h
index 75d3a53..0e96a1d 100644
--- a/usr.sbin/bhyve/virtio.h
+++ b/usr.sbin/bhyve/virtio.h
@@ -453,6 +453,7 @@ void	vi_set_io_bar(struct virtio_softc *, int);
 
 int	vq_getchain(struct vqueue_info *vq, uint16_t *pidx,
 		    struct iovec *iov, int n_iov, uint16_t *flags);
+void	vq_retchain(struct vqueue_info *vq);
 void	vq_relchain(struct vqueue_info *vq, uint16_t idx, uint32_t iolen);
 void	vq_endchains(struct vqueue_info *vq, int used_all_avail);