[PATCH 10/33] vhost: vhost_virtqueue_start(): fix failure path

[Vladimir Sementsov-Ogievskiy]

We miss call to unmap in cases when vhost_memory_map() returns
lenght less than requested (still we consider such cases as an
error). Let's fix it in vhost_memory_map().

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsement...@yandex-team.ru>
---
 hw/virtio/vhost.c | 33 +++++++++++++++++++++------------
 1 file changed, 21 insertions(+), 12 deletions(-)

diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
index 2631bbabcf..1e14987cd5 100644
--- a/hw/virtio/vhost.c
+++ b/hw/virtio/vhost.c
@@ -467,10 +467,19 @@ static inline void vhost_dev_log_resize(struct vhost_dev 
*dev, uint64_t size)
 }
 
 static void *vhost_memory_map(struct vhost_dev *dev, hwaddr addr,
-                              hwaddr *plen, bool is_write)
+                              hwaddr len, bool is_write)
 {
+    hwaddr mapped_len = len;
     if (!vhost_dev_has_iommu(dev)) {
-        return cpu_physical_memory_map(addr, plen, is_write);
+        void *res = cpu_physical_memory_map(addr, &mapped_len, is_write);
+        if (!res) {
+            return NULL;
+        }
+        if (len != mapped_len) {
+            cpu_physical_memory_unmap(res, mapped_len, 0, 0);
+            return NULL;
+        }
+        return res;
     } else {
         return (void *)(uintptr_t)addr;
     }
@@ -1259,7 +1268,7 @@ int vhost_virtqueue_start(struct vhost_dev *dev,
     BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev)));
     VirtioBusState *vbus = VIRTIO_BUS(qbus);
     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(vbus);
-    hwaddr s, l, a;
+    hwaddr l, a;
     int r;
     int vhost_vq_index = dev->vhost_ops->vhost_get_vq_index(dev, idx);
     struct vhost_vring_file file = {
@@ -1299,24 +1308,24 @@ int vhost_virtqueue_start(struct vhost_dev *dev,
         }
     }
 
-    vq->desc_size = s = l = virtio_queue_get_desc_size(vdev, idx);
+    vq->desc_size = l = virtio_queue_get_desc_size(vdev, idx);
     vq->desc_phys = a;
-    vq->desc = vhost_memory_map(dev, a, &l, false);
-    if (!vq->desc || l != s) {
+    vq->desc = vhost_memory_map(dev, a, l, false);
+    if (!vq->desc) {
         r = -ENOMEM;
         goto fail_alloc_desc;
     }
-    vq->avail_size = s = l = virtio_queue_get_avail_size(vdev, idx);
+    vq->avail_size = l = virtio_queue_get_avail_size(vdev, idx);
     vq->avail_phys = a = virtio_queue_get_avail_addr(vdev, idx);
-    vq->avail = vhost_memory_map(dev, a, &l, false);
-    if (!vq->avail || l != s) {
+    vq->avail = vhost_memory_map(dev, a, l, false);
+    if (!vq->avail) {
         r = -ENOMEM;
         goto fail_alloc_avail;
     }
-    vq->used_size = s = l = virtio_queue_get_used_size(vdev, idx);
+    vq->used_size = l = virtio_queue_get_used_size(vdev, idx);
     vq->used_phys = a = virtio_queue_get_used_addr(vdev, idx);
-    vq->used = vhost_memory_map(dev, a, &l, true);
-    if (!vq->used || l != s) {
+    vq->used = vhost_memory_map(dev, a, l, true);
+    if (!vq->used) {
         r = -ENOMEM;
         goto fail_alloc_used;
     }
-- 
2.48.1