Stefano Garzarella <sgarz...@redhat.com> writes:
> The virtio-blk-vhost-vdpa driver in libblkio 1.3.0 supports the fd
> passing through the new 'fd' property.
>
> Since now we are using qemu_open() on '@path' if the virtio-blk driver
> supports the fd passing, let's announce it.
> In this way, the management layer can pass the file descriptor of an
> already opened vhost-vdpa character device. This is useful especially
> when the device can only be accessed with certain privileges.
>
> Add the '@fdset' feature only when the virtio-blk-vhost-vdpa driver
> in libblkio supports it.
>
> Suggested-by: Markus Armbruster <arm...@redhat.com>
> Signed-off-by: Stefano Garzarella <sgarz...@redhat.com>
> ---
>
> Notes:
> v4:
> - added this patch to allow libvirt to discover we support fdset [Markus]
>
> meson.build | 4 ++++
> qapi/block-core.json | 8 +++++++-
> 2 files changed, 11 insertions(+), 1 deletion(-)
>
> diff --git a/meson.build b/meson.build
> index 78890f0155..8ea911f7b4 100644
> --- a/meson.build
> +++ b/meson.build
> @@ -2108,6 +2108,10 @@ config_host_data.set('CONFIG_LZO', lzo.found())
> config_host_data.set('CONFIG_MPATH', mpathpersist.found())
> config_host_data.set('CONFIG_MPATH_NEW_API', mpathpersist_new_api)
> config_host_data.set('CONFIG_BLKIO', blkio.found())
> +if blkio.found()
> + config_host_data.set('CONFIG_BLKIO_VHOST_VDPA_FD',
> + blkio.version().version_compare('>=1.3.0'))
> +endif
> config_host_data.set('CONFIG_CURL', curl.found())
> config_host_data.set('CONFIG_CURSES', curses.found())
> config_host_data.set('CONFIG_GBM', gbm.found())
> diff --git a/qapi/block-core.json b/qapi/block-core.json
> index 98d9116dae..1538d84ef4 100644
> --- a/qapi/block-core.json
> +++ b/qapi/block-core.json
> @@ -3955,10 +3955,16 @@
> #
> # @path: path to the vhost-vdpa character device.
> #
> +# Features:
> +# @fdset: Member @path supports the special "/dev/fdset/N" path (since 8.1)
Slightly long line, break it like this:
# @fdset: Member @path supports the special "/dev/fdset/N" path
# since 8.1)
> +#
> # Since: 7.2
> ##
> { 'struct': 'BlockdevOptionsVirtioBlkVhostVdpa',
> - 'data': { 'path': 'str' },
> + 'data': { 'path': { 'type': 'str',
> + 'features': [ { 'name' :'fdset',
> + 'if': 'CONFIG_BLKIO_VHOST_VDPA_FD' } ]
> + } },
> 'if': 'CONFIG_BLKIO' }
>
> ##
Tacking the feature to the member works.
For what it's worth, the existing features serving similar purposes are
all tacked to the command or type.
Do libvirt developers have a preference?
