From: Philippe Mathieu-Daudé <philmd@redhat.com>

When building QEMU with --disable-vhost-user and using introspection,
query-qmp-schema lists vhost-user-blk even though it's not actually
available:

  { "execute": "query-qmp-schema" }
  {
      "return": [
          ...
          {
              "name": "312",
              "members": [
                  {
                      "name": "nbd"
                  },
                  {
                      "name": "vhost-user-blk"
                  }
              ],
              "meta-type": "enum",
              "values": [
                  "nbd",
                  "vhost-user-blk"
              ]
          },

Restrict vhost-user-blk in BlockExportType when
CONFIG_VHOST_USER_BLK_SERVER is disabled, so it
doesn't end listed by query-qmp-schema.

Fixes: 90fc91d50b7 ("convert vhost-user-blk server to block export API")
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <20220107105420.395011-4-f4bug@amsat.org>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 qapi/block-export.json | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/qapi/block-export.json b/qapi/block-export.json
index c1b92ce1c1..f9ce79a974 100644
--- a/qapi/block-export.json
+++ b/qapi/block-export.json
@@ -277,7 +277,8 @@
 # Since: 4.2
 ##
 { 'enum': 'BlockExportType',
-  'data': [ 'nbd', 'vhost-user-blk',
+  'data': [ 'nbd',
+            { 'name': 'vhost-user-blk', 'if': 'CONFIG_VHOST_USER_BLK_SERVER' },
             { 'name': 'fuse', 'if': 'CONFIG_FUSE' } ] }
 
 ##
@@ -319,7 +320,8 @@
   'discriminator': 'type',
   'data': {
       'nbd': 'BlockExportOptionsNbd',
-      'vhost-user-blk': 'BlockExportOptionsVhostUserBlk',
+      'vhost-user-blk': { 'type': 'BlockExportOptionsVhostUserBlk',
+                          'if': 'CONFIG_VHOST_USER_BLK_SERVER' },
       'fuse': { 'type': 'BlockExportOptionsFuse',
                 'if': 'CONFIG_FUSE' }
    } }
-- 
2.31.1

On 14/1/22 14:52, Kevin Wolf wrote:
> From: Philippe Mathieu-Daudé <philmd@redhat.com>
> 
> When building QEMU with --disable-vhost-user and using introspection,
> query-qmp-schema lists vhost-user-blk even though it's not actually
> available:
> 
>    { "execute": "query-qmp-schema" }
>    {
>        "return": [
>            ...
>            {
>                "name": "312",
>                "members": [
>                    {
>                        "name": "nbd"
>                    },
>                    {
>                        "name": "vhost-user-blk"
>                    }
>                ],
>                "meta-type": "enum",
>                "values": [
>                    "nbd",
>                    "vhost-user-blk"
>                ]
>            },
> 
> Restrict vhost-user-blk in BlockExportType when
> CONFIG_VHOST_USER_BLK_SERVER is disabled, so it
> doesn't end listed by query-qmp-schema.
> 
> Fixes: 90fc91d50b7 ("convert vhost-user-blk server to block export API")
> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
> Message-Id: <20220107105420.395011-4-f4bug@amsat.org>
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
>   qapi/block-export.json | 6 ++++--
>   1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/qapi/block-export.json b/qapi/block-export.json
> index c1b92ce1c1..f9ce79a974 100644
> --- a/qapi/block-export.json
> +++ b/qapi/block-export.json
> @@ -277,7 +277,8 @@
>   # Since: 4.2
>   ##
>   { 'enum': 'BlockExportType',
> -  'data': [ 'nbd', 'vhost-user-blk',
> +  'data': [ 'nbd',
> +            { 'name': 'vhost-user-blk', 'if': 'CONFIG_VHOST_USER_BLK_SERVER' },
>               { 'name': 'fuse', 'if': 'CONFIG_FUSE' } ] }

Markus asked to split this line:
https://lore.kernel.org/qemu-devel/87zgny37s8.fsf@dusky.pond.sub.org/
I will add a cleanup patch, no need to cancel this PR for that ;)