[PATCH v5 08/26] vhost: retry translating IOVA after IOTLB miss

[Maxime Coquelin <maxime.coquelin@redhat.com>]

Vhost-user backend IOTLB misses and updates are
asynchronous, so IOVA address translation function
just fails after having sent an IOTLB miss update if needed
entry was not in the IOTLB cache.

This is not the case for VDUSE, for which the needed IOTLB
update is returned directly when sending an IOTLB miss.

This patch retry again finding the needed entry in the
IOTLB cache after having sent an IOTLB miss.

Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
Reviewed-by: Chenbo Xia <chenbo.xia@intel.com>
---
 lib/vhost/vhost.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/lib/vhost/vhost.c b/lib/vhost/vhost.c
index 3ddd2a963f..7e1af487c1 100644
--- a/lib/vhost/vhost.c
+++ b/lib/vhost/vhost.c
@@ -100,6 +100,12 @@ __vhost_iova_to_vva(struct virtio_net *dev, struct vhost_virtqueue *vq,
 		vhost_user_iotlb_rd_lock(vq);
 	}
 
+	tmp_size = *size;
+	/* Retry in case of VDUSE, as it is synchronous */
+	vva = vhost_user_iotlb_cache_find(dev, iova, &tmp_size, perm);
+	if (tmp_size == *size)
+		return vva;
+
 	return 0;
 }
 
-- 
2.40.1