On Sat, Jan 22, 2022 at 12:10:35 +0800, yshxxsjt715@gmail.com wrote:
> From: shenjiatong <yshxxsjt715@gmail.com>
>
> When trying to attach vhost-user-blk device to virtual
> machine using libvirt 7.8 and qemu 4.2. Libvirt mistakenly
> add a scsi=off parameter which is not supported by Qemu
>
> Signed-off-by: shenjiatong <yshxxsjt715@gmail.com>
> ---
>  src/qemu/qemu_command.c                                     | 6 +++++-
>  .../qemuxml2argvdata/disk-vhostuser-numa.x86_64-4.2.0.args  | 4 ++--
>  2 files changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
> index 662d15e28e..cdf89fc74c 100644
> --- a/src/qemu/qemu_command.c
> +++ b/src/qemu/qemu_command.c
> @@ -2253,11 +2253,15 @@ qemuBuildDiskDeviceProps(const virDomainDef *def,
>                                    "S:iothread", iothread,
>                                    "T:ioeventfd", disk->ioeventfd,
>                                    "T:event_idx", disk->event_idx,
> -                                  "T:scsi", scsi,

Rather than moving this line out of the formatter,

>                                    "p:num-queues", disk->queues,
>                                    "p:queue-size", disk->queue_size,
>                                    NULL) < 0)
>              return NULL;
> +
> +        if (virStorageSourceGetActualType(disk->src) != VIR_STORAGE_TYPE_VHOST_USER) {
> +          if (virJSONValueObjectAdd(&props, "T:scsi", scsi, NULL) < 0)

you can simply skip the code that assigns VIR_TRISTATE_SWITCH_ON/OFF to
the 'scsi' value. By default the formatter doesn't print anything for
the _ABSENT case.

If you don't mind I can do that before pushing so you don't have to send
another round.