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/block/vhost-user-blk.c b/hw/block/vhost-user-blk.c
index e9382e1..3770f71 100644
--- a/hw/block/vhost-user-blk.c
+++ b/hw/block/vhost-user-blk.c
@@ -91,11 +91,13 @@ static int vhost_user_blk_handle_config_change(struct vhost_dev *dev)
     int ret;
     struct virtio_blk_config blkcfg;
     VHostUserBlk *s = VHOST_USER_BLK(dev->vdev);
+    Error *local_err = NULL;
 
     ret = vhost_dev_get_config(dev, (uint8_t *)&blkcfg,
-                               sizeof(struct virtio_blk_config));
+                               sizeof(struct virtio_blk_config),
+                               &local_err);
     if (ret < 0) {
-        error_report("get config space failed");
+        error_report_err(local_err);
         return -1;
     }
 
@@ -478,9 +480,8 @@ static void vhost_user_blk_device_realize(DeviceState *dev, Error **errp)
     assert(s->connected);
 
     ret = vhost_dev_get_config(&s->dev, (uint8_t *)&s->blkcfg,
-                               sizeof(struct virtio_blk_config));
+                               sizeof(struct virtio_blk_config), errp);
     if (ret < 0) {
-        error_setg(errp, "vhost-user-blk: get block config failed");
         goto vhost_err;
     }