Re: [RFC v1 3/4] vhost-vdpa: implement vhost-vdpa backend

[Maxime Coquelin <maxime.coquelin@redhat.com>]

On 4/20/20 11:32 AM, Cindy Lu wrote:
> Currently we have 2 types of vhost backends in QEMU: vhost kernel and
> vhost-user. The above patch provides a generic device for vDPA purpose,
> this vDPA device exposes to user space a non-vendor-specific configuration
> interface for setting up a vhost HW accelerator, this patch set introduces
> a third vhost backend called vhost-vdpa based on the vDPA interface.
> 
> Vhost-vdpa usage:
> 
>   qemu-system-x86_64 -cpu host -enable-kvm \
>     ......
>   -netdev type=vhost-vdpa,vhostdev=/dev/vhost-vdpa-id,id=vhost-vdpa0 \
>   -device virtio-net-pci,netdev=vhost-vdpa0,page-per-vq=on \
> 
> Author: Tiwei Bie
> Signed-off-by: Cindy Lu <lulu@redhat.com>
> ---
>  hw/net/vhost_net.c                |  43 ++++
>  hw/net/virtio-net.c               |   9 +
>  hw/virtio/Makefile.objs           |   2 +-
>  hw/virtio/vhost-backend.c         |   3 +
>  hw/virtio/vhost-vdpa.c            | 379 ++++++++++++++++++++++++++++++
>  hw/virtio/vhost.c                 |   5 +
>  include/hw/virtio/vhost-backend.h |   6 +-
>  include/hw/virtio/vhost-vdpa.h    |  14 ++
>  8 files changed, 459 insertions(+), 2 deletions(-)
>  create mode 100644 hw/virtio/vhost-vdpa.c
>  create mode 100644 include/hw/virtio/vhost-vdpa.h
> 
> diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c
> index 4096d64aaf..0d13fda2fc 100644
> --- a/hw/net/vhost_net.c
> +++ b/hw/net/vhost_net.c
> @@ -17,8 +17,10 @@
>  #include "net/net.h"
>  #include "net/tap.h"
>  #include "net/vhost-user.h"
> +#include "net/vhost-vdpa.h"
>  
>  #include "standard-headers/linux/vhost_types.h"
> +#include "linux-headers/linux/vhost.h"
>  #include "hw/virtio/virtio-net.h"
>  #include "net/vhost_net.h"
>  #include "qemu/error-report.h"
> @@ -85,6 +87,29 @@ static const int user_feature_bits[] = {
>      VHOST_INVALID_FEATURE_BIT
>  };
>  
> +static const int vdpa_feature_bits[] = {
> +    VIRTIO_F_NOTIFY_ON_EMPTY,
> +    VIRTIO_RING_F_INDIRECT_DESC,
> +    VIRTIO_RING_F_EVENT_IDX,
> +    VIRTIO_F_ANY_LAYOUT,
> +    VIRTIO_F_VERSION_1,
> +    VIRTIO_NET_F_CSUM,
> +    VIRTIO_NET_F_GUEST_CSUM,
> +    VIRTIO_NET_F_GSO,
> +    VIRTIO_NET_F_GUEST_TSO4,
> +    VIRTIO_NET_F_GUEST_TSO6,
> +    VIRTIO_NET_F_GUEST_ECN,
> +    VIRTIO_NET_F_GUEST_UFO,
> +    VIRTIO_NET_F_HOST_TSO4,
> +    VIRTIO_NET_F_HOST_TSO6,
> +    VIRTIO_NET_F_HOST_ECN,
> +    VIRTIO_NET_F_HOST_UFO,
> +    VIRTIO_NET_F_MRG_RXBUF,
> +    VIRTIO_NET_F_MTU,
> +    VIRTIO_F_IOMMU_PLATFORM,
> +    VIRTIO_NET_F_GUEST_ANNOUNCE,
> +    VHOST_INVALID_FEATURE_BIT
> +};
>  static const int *vhost_net_get_feature_bits(struct vhost_net *net)
>  {
>      const int *feature_bits = 0;
> @@ -96,6 +121,9 @@ static const int *vhost_net_get_feature_bits(struct vhost_net *net)
>      case NET_CLIENT_DRIVER_VHOST_USER:
>          feature_bits = user_feature_bits;
>          break;
> +    case NET_CLIENT_DRIVER_VHOST_VDPA:
> +        feature_bits = vdpa_feature_bits;
> +        break;
>      default:
>          error_report("Feature bits not defined for this type: %d",
>                  net->nc->info->type);
> @@ -434,6 +462,10 @@ VHostNetState *get_vhost_net(NetClientState *nc)
>          assert(vhost_net);
>          break;
>  #endif
> +    case NET_CLIENT_DRIVER_VHOST_VDPA:
> +        vhost_net = vhost_vdpa_get_vhost_net(nc);
> +        assert(vhost_net);
> +        break;
>      default:
>          break;
>      }
> @@ -465,3 +497,14 @@ int vhost_net_set_mtu(struct vhost_net *net, uint16_t mtu)
>  
>      return vhost_ops->vhost_net_set_mtu(&net->dev, mtu);
>  }
> +int vhost_set_state(NetClientState *nc, int state)
> +{
> +    struct vhost_net *net = get_vhost_net(nc);
> +    struct vhost_dev *hdev = &net->dev;
> +    if (nc->info->type == NET_CLIENT_DRIVER_VHOST_VDPA) {

Maybe checking the vhost_set_state callback is implemented is enough,
and it is not need to restrict that to Vhost-vDPA?

> +        if (hdev->vhost_ops->vhost_set_state) {
> +                return hdev->vhost_ops->vhost_set_state(hdev, state);
> +             }
> +        }
> +    return 0;
> +}