vhost: init used ring after backend was set
Move the used ring initialization after backend was set. This
makes it possible to disable the backend and tweak the used ring,
then restart. This will also make it possible to log the used ring
write correctly.
Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index f0fd52c..70ac604 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -703,6 +703,10 @@
vhost_net_disable_vq(n, vq);
rcu_assign_pointer(vq->private_data, sock);
vhost_net_enable_vq(n, vq);
+
+ r = vhost_init_used(vq);
+ if (r)
+ goto err_vq;
}
mutex_unlock(&vq->mutex);
diff --git a/drivers/vhost/test.c b/drivers/vhost/test.c
index 734e1d7..fc9a1d7 100644
--- a/drivers/vhost/test.c
+++ b/drivers/vhost/test.c
@@ -195,8 +195,13 @@
lockdep_is_held(&vq->mutex));
rcu_assign_pointer(vq->private_data, priv);
+ r = vhost_init_used(&n->vqs[index]);
+
mutex_unlock(&vq->mutex);
+ if (r)
+ goto err;
+
if (oldpriv) {
vhost_test_flush_vq(n, index);
}
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 5ef2f62..9a10803 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -629,15 +629,17 @@
return 0;
}
-static int init_used(struct vhost_virtqueue *vq,
- struct vring_used __user *used)
+int vhost_init_used(struct vhost_virtqueue *vq)
{
- int r = put_user(vq->used_flags, &used->flags);
+ int r;
+ if (!vq->private_data)
+ return 0;
+ r = put_user(vq->used_flags, &vq->used->flags);
if (r)
return r;
vq->signalled_used_valid = false;
- return get_user(vq->last_used_idx, &used->idx);
+ return get_user(vq->last_used_idx, &vq->used->idx);
}
static long vhost_set_vring(struct vhost_dev *d, int ioctl, void __user *argp)
@@ -752,10 +754,6 @@
}
}
- r = init_used(vq, (struct vring_used __user *)(unsigned long)
- a.used_user_addr);
- if (r)
- break;
vq->log_used = !!(a.flags & (0x1 << VHOST_VRING_F_LOG));
vq->desc = (void __user *)(unsigned long)a.desc_user_addr;
vq->avail = (void __user *)(unsigned long)a.avail_user_addr;
diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
index 1544b78..14c9abf 100644
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h
@@ -174,6 +174,7 @@
struct vhost_log *log, unsigned int *log_num);
void vhost_discard_vq_desc(struct vhost_virtqueue *, int n);
+int vhost_init_used(struct vhost_virtqueue *);
int vhost_add_used(struct vhost_virtqueue *, unsigned int head, int len);
int vhost_add_used_n(struct vhost_virtqueue *, struct vring_used_elem *heads,
unsigned count);