Re: [PATCH v2 0/2] block/blkio: add 'fd' option to virtio-blk-vhost-vdpa driver

[Jonathon Jongsma]

On 5/4/23 4:28 AM, Stefano Garzarella wrote:
> v2:
> - added patch 01 to use monitor_fd_param() in the blkio module
> - use monitor_fd_param() to parse the fd like vhost devices [Stefan]
>
> v1: 
> 20230502145050.224615-1-sgarzare@redhat.com/">https://lore.kernel.org/qemu-devel/20230502145050.224615-1-sgarzare@redhat.com/
>
> The virtio-blk-vhost-vdpa driver in libblkio 1.3.0 supports the new
> 'fd' property. Let's expose this to the user, so 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.
>
> Stefano Garzarella (2):
>    stubs/monitor: add monitor_fd_param()
>    block/blkio: add 'fd' option to virtio-blk-vhost-vdpa driver
>
>   qapi/block-core.json |  6 ++++-
>   block/blkio.c        | 53 +++++++++++++++++++++++++++++++++++++++++++-
>   stubs/monitor.c      |  6 +++++
>   3 files changed, 63 insertions(+), 2 deletions(-)


I mentioned this briefly off-list, but I'm following up here just to 
provide a bit more visibility. From libvirt's point of view, it is 
actually much easier if we could pass the fd via the existing 'path' 
parameter (using /dev/fdset/N as the path, for example) due to how we 
construct the commandline for qemu. So if I get a vote, I would 
definitely vote for that approach over adding a new 'fd' property.

Thanks,
Jonathon