vhost: Distinguish errors in vhost_dev_get_config()

Instead of just returning 0/-1 and letting the caller make up a
meaningless error message, add an Error parameter to allow reporting the
real error and switch to 0/-errno so that different kind of errors can
be distinguished in the caller.

config_len in vhost_user_get_config() is defined by the device, so if
it's larger than VHOST_USER_MAX_CONFIG_SIZE, this is a programming
error. Turn the corresponding check into an assertion.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20210609154658.350308-6-kwolf@redhat.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Reviewed-by: Raphael Norwitz <raphael.norwitz@nutanix.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

1 files changed, 5 insertions, 4 deletions

diff --git a/hw/virtio/vhost-user-vsock.c b/hw/virtio/vhost-user-vsock.c
index b6a4a25ea1..6095ed7349 100644
--- a/hw/virtio/vhost-user-vsock.c
+++ b/hw/virtio/vhost-user-vsock.c
@@ -34,10 +34,12 @@ static void vuv_get_config(VirtIODevice *vdev, uint8_t *config)
 static int vuv_handle_config_change(struct vhost_dev *dev)
 {
     VHostUserVSock *vsock = VHOST_USER_VSOCK(dev->vdev);
+    Error *local_err = NULL;
     int ret = vhost_dev_get_config(dev, (uint8_t *)&vsock->vsockcfg,
-                                   sizeof(struct virtio_vsock_config));
+                                   sizeof(struct virtio_vsock_config),
+                                   &local_err);
     if (ret < 0) {
-        error_report("get config space failed");
+        error_report_err(local_err);
         return -1;
     }
 
@@ -114,9 +116,8 @@ static void vuv_device_realize(DeviceState *dev, Error **errp)
     }
 
     ret = vhost_dev_get_config(&vvc->vhost_dev, (uint8_t *)&vsock->vsockcfg,
-                               sizeof(struct virtio_vsock_config));
+                               sizeof(struct virtio_vsock_config), errp);
     if (ret < 0) {
-        error_setg_errno(errp, -ret, "get config space failed");
         goto err_vhost_dev;
     }