Re: [Qemu-devel] [PATCH v11 7/7] vhost-user: add a new message to disable/enable a specific virt queue.

[Jason Wang <jasowang@redhat.com>]

On 09/23/2015 12:20 PM, 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>

Reviewed-by: Jason Wang <jasowang@redhat.com>

>
> ---
> v11: fix typo
> ---
>  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..4eadad1 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 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.
> diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c
> index ad82b5c..2bce891 100644
> --- a/hw/net/vhost_net.c
> +++ b/hw/net/vhost_net.c
> @@ -422,6 +422,19 @@ VHostNetState *get_vhost_net(NetClientState *nc)
>  
>      return vhost_net;
>  }
> +
> +int vhost_set_vring_enable(NetClientState *nc, int enable)
> +{
> +    VHostNetState *net = get_vhost_net(nc);
> +    const VhostOps *vhost_ops = net->dev.vhost_ops;
> +
> +    if (vhost_ops->vhost_backend_set_vring_enable) {
> +        return vhost_ops->vhost_backend_set_vring_enable(&net->dev, enable);
> +    }
> +
> +    return 0;
> +}
> +
>  #else
>  uint64_t vhost_net_get_max_queues(VHostNetState *net)
>  {
> @@ -472,4 +485,9 @@ VHostNetState *get_vhost_net(NetClientState *nc)
>  {
>      return 0;
>  }
> +
> +int vhost_set_vring_enable(NetClientState *nc, int enable)
> +{
> +    return 0;
> +}
>  #endif
> diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
> index f72eebf..916222f 100644
> --- a/hw/net/virtio-net.c
> +++ b/hw/net/virtio-net.c
> @@ -406,6 +406,10 @@ static int peer_attach(VirtIONet *n, int index)
>          return 0;
>      }
>  
> +    if (nc->peer->info->type == NET_CLIENT_OPTIONS_KIND_VHOST_USER) {
> +        vhost_set_vring_enable(nc->peer, 1);
> +    }
> +
>      if (nc->peer->info->type != NET_CLIENT_OPTIONS_KIND_TAP) {
>          return 0;
>      }
> @@ -421,6 +425,10 @@ static int peer_detach(VirtIONet *n, int index)
>          return 0;
>      }
>  
> +    if (nc->peer->info->type == NET_CLIENT_OPTIONS_KIND_VHOST_USER) {
> +        vhost_set_vring_enable(nc->peer, 0);
> +    }
> +
>      if (nc->peer->info->type !=  NET_CLIENT_OPTIONS_KIND_TAP) {
>          return 0;
>      }
> diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
> index e42fde6..b11c0d2 100644
> --- a/hw/virtio/vhost-user.c
> +++ b/hw/virtio/vhost-user.c
> @@ -48,6 +48,7 @@ typedef enum VhostUserRequest {
>      VHOST_USER_GET_PROTOCOL_FEATURES = 15,
>      VHOST_USER_SET_PROTOCOL_FEATURES = 16,
>      VHOST_USER_GET_QUEUE_NUM = 17,
> +    VHOST_USER_SET_VRING_ENABLE = 18,
>      VHOST_USER_MAX
>  } VhostUserRequest;
>  
> @@ -290,6 +291,7 @@ static int vhost_user_call(struct vhost_dev *dev, unsigned long int request,
>  
>      case VHOST_USER_SET_VRING_NUM:
>      case VHOST_USER_SET_VRING_BASE:
> +    case VHOST_USER_SET_VRING_ENABLE:
>          memcpy(&msg.state, arg, sizeof(struct vhost_vring_state));
>          msg.size = sizeof(m.state);
>          break;
> @@ -406,6 +408,22 @@ static int vhost_user_init(struct vhost_dev *dev, void *opaque)
>      return 0;
>  }
>  
> +static int vhost_user_set_vring_enable(struct vhost_dev *dev, int enable)
> +{
> +    struct vhost_vring_state state = {
> +        .index = dev->vq_index,
> +        .num   = enable,
> +    };
> +
> +    assert(dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_USER);
> +
> +    if (!(dev->protocol_features & (1ULL << VHOST_USER_PROTOCOL_F_MQ))) {
> +        return -1;
> +    }
> +
> +    return vhost_user_call(dev, VHOST_USER_SET_VRING_ENABLE, &state);
> +}
> +
>  static int vhost_user_cleanup(struct vhost_dev *dev)
>  {
>      assert(dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_USER);
> @@ -428,4 +446,5 @@ const VhostOps user_ops = {
>          .vhost_backend_init = vhost_user_init,
>          .vhost_backend_cleanup = vhost_user_cleanup,
>          .vhost_backend_get_vq_index = vhost_user_get_vq_index,
> +        .vhost_backend_set_vring_enable = vhost_user_set_vring_enable,
>  };
> diff --git a/include/hw/virtio/vhost-backend.h b/include/hw/virtio/vhost-backend.h
> index e1dfc6d..3a0f6e2 100644
> --- a/include/hw/virtio/vhost-backend.h
> +++ b/include/hw/virtio/vhost-backend.h
> @@ -25,6 +25,7 @@ typedef int (*vhost_call)(struct vhost_dev *dev, unsigned long int request,
>  typedef int (*vhost_backend_init)(struct vhost_dev *dev, void *opaque);
>  typedef int (*vhost_backend_cleanup)(struct vhost_dev *dev);
>  typedef int (*vhost_backend_get_vq_index)(struct vhost_dev *dev, int idx);
> +typedef int (*vhost_backend_set_vring_enable)(struct vhost_dev *dev, int enable);
>  
>  typedef struct VhostOps {
>      VhostBackendType backend_type;
> @@ -32,6 +33,7 @@ typedef struct VhostOps {
>      vhost_backend_init vhost_backend_init;
>      vhost_backend_cleanup vhost_backend_cleanup;
>      vhost_backend_get_vq_index vhost_backend_get_vq_index;
> +    vhost_backend_set_vring_enable vhost_backend_set_vring_enable;
>  } VhostOps;
>  
>  extern const VhostOps user_ops;
> diff --git a/include/net/vhost_net.h b/include/net/vhost_net.h
> index 8db723e..0188c4d 100644
> --- a/include/net/vhost_net.h
> +++ b/include/net/vhost_net.h
> @@ -28,4 +28,6 @@ bool vhost_net_virtqueue_pending(VHostNetState *net, int n);
>  void vhost_net_virtqueue_mask(VHostNetState *net, VirtIODevice *dev,
>                                int idx, bool mask);
>  VHostNetState *get_vhost_net(NetClientState *nc);
> +
> +int vhost_set_vring_enable(NetClientState * nc, int enable);
>  #endif