Re: [RFC 08/10] vhost: Add x-vhost-enable-shadow-vq qmp

[Eric Blake <eblake@redhat.com>]

On 1/29/21 2:54 PM, Eugenio Pérez wrote:
> Command to enable shadow virtqueue looks like:
> 
> { "execute": "x-vhost-enable-shadow-vq", "arguments": { "name": "dev0", "enable": true } }
> 
> Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
> ---
>  qapi/net.json     | 23 +++++++++++++++++++++++
>  hw/virtio/vhost.c |  6 ++++++
>  2 files changed, 29 insertions(+)
> 
> diff --git a/qapi/net.json b/qapi/net.json
> index c31748c87f..6170d69798 100644
> --- a/qapi/net.json
> +++ b/qapi/net.json
> @@ -77,6 +77,29 @@
>  ##
>  { 'command': 'netdev_del', 'data': {'id': 'str'} }
>  
> +##
> +# @x-vhost-enable-shadow-vq:

This spelling is the preferred form...[1]

> +#
> +# Use vhost shadow virtqueue.
> +#
> +# @name: the device name of the virtual network adapter
> +#
> +# @enable: true to use he alternate shadow VQ notification path
> +#
> +# Returns: Error if failure, or 'no error' for success

This line...[2]

> +#
> +# Since: 5.3

The next release is 6.0, not 5.3.

> +#
> +# Example:
> +#
> +# -> { "execute": "x-vhost_enable_shadow_vq", "arguments": {"enable": true} }

[1]...but doesn't match the example.

> +# <- { "return": { "enabled" : true } }

[2]...doesn't match this comment.  I'd just drop the line, since there
is no explicit return listed.

> +#
> +##
> +{ 'command': 'x-vhost-enable-shadow-vq',
> +  'data': {'name': 'str', 'enable': 'bool'},
> +  'if': 'defined(CONFIG_VHOST_KERNEL)' }
> +
>  ##
>  # @NetLegacyNicOptions:
>  #
> diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
> index 040f68ff2e..42836e45f3 100644
> --- a/hw/virtio/vhost.c
> +++ b/hw/virtio/vhost.c
> @@ -15,6 +15,7 @@
>  
>  #include "qemu/osdep.h"
>  #include "qapi/error.h"
> +#include "qapi/qapi-commands-net.h"
>  #include "hw/virtio/vhost.h"
>  #include "qemu/atomic.h"
>  #include "qemu/range.h"
> @@ -1841,3 +1842,8 @@ int vhost_net_set_backend(struct vhost_dev *hdev,
>  
>      return -1;
>  }
> +
> +void qmp_x_vhost_enable_shadow_vq(const char *name, bool enable, Error **errp)
> +{
> +    error_setg(errp, "Shadow virtqueue still not implemented.");

error_setg() should not be passed a trailing '.'.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org