virtio/s390: handle failures of READ_VQ_CONF ccw

In virtio_ccw_read_vq_conf() the return value of ccw_io_helper()
was not checked.
If the configuration could not be read properly, we'd wrongly assume a
queue size of 0.

Let's propagate any I/O error to virtio_ccw_setup_vq() so it may
properly fail.

Signed-off-by: Pierre Morel <pmorel@linux.vnet.ibm.com>
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

diff --git a/drivers/s390/virtio/virtio_ccw.c b/drivers/s390/virtio/virtio_ccw.c
index f8d8fdb..e9fae30 100644 (file)
--- a/drivers/s390/virtio/virtio_ccw.c
+++ b/drivers/s390/virtio/virtio_ccw.c
@@ -400,12 +400,16 @@ static bool virtio_ccw_kvm_notify(struct virtqueue *vq)
 static int virtio_ccw_read_vq_conf(struct virtio_ccw_device *vcdev,
                                   struct ccw1 *ccw, int index)
 {
+       int ret;
+
        vcdev->config_block->index = index;
        ccw->cmd_code = CCW_CMD_READ_VQ_CONF;
        ccw->flags = 0;
        ccw->count = sizeof(struct vq_config_block);
        ccw->cda = (__u32)(unsigned long)(vcdev->config_block);
-       ccw_io_helper(vcdev, ccw, VIRTIO_CCW_DOING_READ_VQ_CONF);
+       ret = ccw_io_helper(vcdev, ccw, VIRTIO_CCW_DOING_READ_VQ_CONF);
+       if (ret)
+               return ret;
        return vcdev->config_block->num;
 }
 
@@ -503,6 +507,10 @@ static struct virtqueue *virtio_ccw_setup_vq(struct virtio_device *vdev,
                goto out_err;
        }
        info->num = virtio_ccw_read_vq_conf(vcdev, ccw, i);
+       if (info->num < 0) {
+               err = info->num;
+               goto out_err;
+       }
        size = PAGE_ALIGN(vring_size(info->num, KVM_VIRTIO_CCW_RING_ALIGN));
        info->queue = alloc_pages_exact(size, GFP_KERNEL | __GFP_ZERO);
        if (info->queue == NULL) {