Re: [Qemu-devel] [PATCH v10 7/7] vhost-user: add a new message to disable/enable a specific virt queue.

[Eric Blake <eblake@redhat.com>]

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On 09/18/2015 08:58 AM, Yuanhan Liu wrote:
> From: Changchun Ouyang <changchun.ouyang@intel.com>
> 
> Add a new message, VHOST_USER_SET_VRING_ENABLE, to enable or disable
> a specific virt queue, which is similar to attach/detach queue for
> tap device.
> 
> virtio driver on guest doesn't have to use max virt queue pair, it
> could enable any number of virt queue ranging from 1 to max virt
> queue pair.
> 
> Signed-off-by: Changchun Ouyang <changchun.ouyang@intel.com>
> Signed-off-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
> ---
>  docs/specs/vhost-user.txt         | 12 +++++++++++-
>  hw/net/vhost_net.c                | 18 ++++++++++++++++++
>  hw/net/virtio-net.c               |  8 ++++++++
>  hw/virtio/vhost-user.c            | 19 +++++++++++++++++++
>  include/hw/virtio/vhost-backend.h |  2 ++
>  include/net/vhost_net.h           |  2 ++
>  6 files changed, 60 insertions(+), 1 deletion(-)
> 
> diff --git a/docs/specs/vhost-user.txt b/docs/specs/vhost-user.txt
> index cfc9d41..a5f1c31 100644
> --- a/docs/specs/vhost-user.txt
> +++ b/docs/specs/vhost-user.txt
> @@ -148,7 +148,9 @@ VHOST_USER_GET_PROTOCOL_FEATURES. Master should stop when the number of
>  requested queues is bigger than that.
>  
>  As all queues share one connection, the master uses a unique index for each
> -queue in the sent message to identify a specified queue.
> +queue in the sent message to identify a specified queue. One queue pairs

s/pairs/pair/

> +is enabled initially. More queues are enabled dynamically, by sending
> +message VHOST_USER_SET_VRING_ENABLE.
>  
>  Message types
>  -------------
> @@ -327,3 +329,11 @@ Message types
>        Query how many queues the backend supports. This request should be
>        sent only when VHOST_USER_PROTOCOL_F_MQ is set in quried protocol
>        features by VHOST_USER_GET_PROTOCOL_FEATURES.
> +
> + * VHOST_USER_SET_VRING_ENABLE
> +
> +      Id: 18
> +      Equivalent ioctl: N/A
> +      Master payload: vring state description
> +
> +      Signal slave to enable or disable corresponding vring.

Does there need to be any QMP control to manually change a given queue,
or is it all used under the hood with no need for management apps to
care other than their initial request of max queues?

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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