Re: [Qemu-devel] [PATCH v10 4/7] vhost-user: add VHOST_USER_GET_QUEUE_NUM message

[Jason Wang <jasowang@redhat.com>]

On 09/18/2015 10:58 PM, Yuanhan Liu wrote:
> This is for querying how many queues the backend supports if it has mq
> support(when VHOST_USER_PROTOCOL_F_MQ flag is set from the quried
> protocol features).
>
> vhost_net_get_max_queues() is the interface to export that value, and
> to tell if the backend supports # of queues user requested, which is
> done in the following patch.
>
> Signed-off-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
> ---
>  docs/specs/vhost-user.txt | 11 +++++++++++
>  hw/net/vhost_net.c        |  7 +++++++
>  hw/virtio/vhost-user.c    | 15 ++++++++++++++-
>  include/hw/virtio/vhost.h |  1 +
>  include/net/vhost_net.h   |  1 +
>  5 files changed, 34 insertions(+), 1 deletion(-)
>
> diff --git a/docs/specs/vhost-user.txt b/docs/specs/vhost-user.txt
> index ccbbcbb..43db9b4 100644
> --- a/docs/specs/vhost-user.txt
> +++ b/docs/specs/vhost-user.txt
> @@ -301,3 +301,14 @@ Message types
>        Bits (0-7) of the payload contain the vring index. Bit 8 is the
>        invalid FD flag. This flag is set when there is no file descriptor
>        in the ancillary data.
> +
> + * VHOST_USER_GET_QUEUE_NUM
> +
> +      Id: 17
> +      Equivalent ioctl: N/A
> +      Master payload: N/A
> +      Slave payload: u64
> +
> +      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.
> diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c
> index b7d29b7..bc88006 100644
> --- a/hw/net/vhost_net.c
> +++ b/hw/net/vhost_net.c
> @@ -122,6 +122,11 @@ void vhost_net_ack_features(struct vhost_net *net, uint64_t features)
>      vhost_ack_features(&net->dev, vhost_net_get_feature_bits(net), features);
>  }
>  
> +uint64_t vhost_net_get_max_queues(VHostNetState *net)
> +{
> +    return net->dev.max_queues;
> +}

Looks like need a dummy function for !CONFIG_VHOST_NET.

> +
>  static int vhost_net_get_fd(NetClientState *backend)
>  {
>      switch (backend->info->type) {
> @@ -144,6 +149,8 @@ struct vhost_net *vhost_net_init(VhostNetOptions *options)
>          goto fail;
>      }
>  
> +    net->dev.max_queues = 1;
> +
>      if (backend_kernel) {
>          r = vhost_net_get_fd(options->net_backend);
>          if (r < 0) {
> diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
> index 9cb2f52..694fde5 100644
> --- a/hw/virtio/vhost-user.c
> +++ b/hw/virtio/vhost-user.c
> @@ -25,7 +25,9 @@
>  
>  #define VHOST_MEMORY_MAX_NREGIONS    8
>  #define VHOST_USER_F_PROTOCOL_FEATURES 30
> -#define VHOST_USER_PROTOCOL_FEATURE_MASK 0x0ULL
> +#define VHOST_USER_PROTOCOL_FEATURE_MASK 0x1ULL
> +
> +#define VHOST_USER_PROTOCOL_F_MQ    0
>  
>  typedef enum VhostUserRequest {
>      VHOST_USER_NONE = 0,
> @@ -45,6 +47,7 @@ typedef enum VhostUserRequest {
>      VHOST_USER_SET_VRING_ERR = 14,
>      VHOST_USER_GET_PROTOCOL_FEATURES = 15,
>      VHOST_USER_SET_PROTOCOL_FEATURES = 16,
> +    VHOST_USER_GET_QUEUE_NUM = 17,
>      VHOST_USER_MAX
>  } VhostUserRequest;
>  
> @@ -211,6 +214,7 @@ static int vhost_user_call(struct vhost_dev *dev, unsigned long int request,
>      switch (msg_request) {
>      case VHOST_USER_GET_FEATURES:
>      case VHOST_USER_GET_PROTOCOL_FEATURES:
> +    case VHOST_USER_GET_QUEUE_NUM:
>          need_reply = 1;
>          break;
>  
> @@ -315,6 +319,7 @@ static int vhost_user_call(struct vhost_dev *dev, unsigned long int request,
>          switch (msg_request) {
>          case VHOST_USER_GET_FEATURES:
>          case VHOST_USER_GET_PROTOCOL_FEATURES:
> +        case VHOST_USER_GET_QUEUE_NUM:
>              if (msg.size != sizeof(m.u64)) {
>                  error_report("Received bad msg size.");
>                  return -1;
> @@ -366,6 +371,14 @@ static int vhost_user_init(struct vhost_dev *dev, void *opaque)
>          if (err < 0) {
>              return err;
>          }
> +
> +        /* query the max queues we support if backend supports Multiple Queue */
> +        if (dev->protocol_features & (1ULL << VHOST_USER_PROTOCOL_F_MQ)) {
> +            err = vhost_user_call(dev, VHOST_USER_GET_QUEUE_NUM, &dev->max_queues);
> +            if (err < 0) {
> +                return err;
> +            }
> +        }
>      }
>  
>      return 0;
> diff --git a/include/hw/virtio/vhost.h b/include/hw/virtio/vhost.h
> index 6467c73..c3758f3 100644
> --- a/include/hw/virtio/vhost.h
> +++ b/include/hw/virtio/vhost.h
> @@ -48,6 +48,7 @@ struct vhost_dev {
>      unsigned long long acked_features;
>      unsigned long long backend_features;
>      unsigned long long protocol_features;
> +    unsigned long long max_queues;
>      bool started;
>      bool log_enabled;
>      unsigned long long log_size;
> diff --git a/include/net/vhost_net.h b/include/net/vhost_net.h
> index 840d4b1..8db723e 100644
> --- a/include/net/vhost_net.h
> +++ b/include/net/vhost_net.h
> @@ -13,6 +13,7 @@ typedef struct VhostNetOptions {
>      void *opaque;
>  } VhostNetOptions;
>  
> +uint64_t vhost_net_get_max_queues(VHostNetState *net);
>  struct vhost_net *vhost_net_init(VhostNetOptions *options);
>  
>  int vhost_net_start(VirtIODevice *dev, NetClientState *ncs, int total_queues);