Re: [RFC PATCH v4 13/20] vdpa: Save host and guest features

[Jason Wang <jasowang@redhat.com>]

在 2021/10/1 下午3:05, Eugenio Pérez 写道:
> Those are needed for SVQ: Host ones are needed to check if SVQ knows
> how to talk with the device and for feature negotiation, and guest ones
> to know if SVQ can talk with it.
>
> Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
> ---
>   include/hw/virtio/vhost-vdpa.h |  2 ++
>   hw/virtio/vhost-vdpa.c         | 31 ++++++++++++++++++++++++++++---
>   2 files changed, 30 insertions(+), 3 deletions(-)
>
> diff --git a/include/hw/virtio/vhost-vdpa.h b/include/hw/virtio/vhost-vdpa.h
> index fddac248b3..9044ae694b 100644
> --- a/include/hw/virtio/vhost-vdpa.h
> +++ b/include/hw/virtio/vhost-vdpa.h
> @@ -26,6 +26,8 @@ typedef struct vhost_vdpa {
>       int device_fd;
>       uint32_t msg_type;
>       MemoryListener listener;
> +    uint64_t host_features;
> +    uint64_t guest_features;


Any reason that we can't use the features stored in VirtioDevice?

Thanks


>       bool shadow_vqs_enabled;
>       GPtrArray *shadow_vqs;
>       struct vhost_dev *dev;
> diff --git a/hw/virtio/vhost-vdpa.c b/hw/virtio/vhost-vdpa.c
> index 6c5f4c98b8..a057e8277d 100644
> --- a/hw/virtio/vhost-vdpa.c
> +++ b/hw/virtio/vhost-vdpa.c
> @@ -439,10 +439,19 @@ static int vhost_vdpa_set_mem_table(struct vhost_dev *dev,
>       return 0;
>   }
>   
> -static int vhost_vdpa_set_features(struct vhost_dev *dev,
> -                                   uint64_t features)
> +/**
> + * Internal set_features() that follows vhost/VirtIO protocol for that
> + */
> +static int vhost_vdpa_backend_set_features(struct vhost_dev *dev,
> +                                           uint64_t features)
>   {
> +    struct vhost_vdpa *v = dev->opaque;
> +
>       int ret;
> +    if (v->host_features & BIT_ULL(VIRTIO_F_QUEUE_STATE)) {
> +        features |= BIT_ULL(VIRTIO_F_QUEUE_STATE);
> +    }
> +
>       trace_vhost_vdpa_set_features(dev, features);
>       ret = vhost_vdpa_call(dev, VHOST_SET_FEATURES, &features);
>       uint8_t status = 0;
> @@ -455,6 +464,17 @@ static int vhost_vdpa_set_features(struct vhost_dev *dev,
>       return !(status & VIRTIO_CONFIG_S_FEATURES_OK);
>   }
>   
> +/**
> + * Exposed vhost set features
> + */
> +static int vhost_vdpa_set_features(struct vhost_dev *dev,
> +                                   uint64_t features)
> +{
> +    struct vhost_vdpa *v = dev->opaque;
> +    v->guest_features = features;
> +    return vhost_vdpa_backend_set_features(dev, features);
> +}
> +
>   static int vhost_vdpa_set_backend_cap(struct vhost_dev *dev)
>   {
>       uint64_t features;
> @@ -673,12 +693,17 @@ static int vhost_vdpa_set_vring_call(struct vhost_dev *dev,
>   }
>   
>   static int vhost_vdpa_get_features(struct vhost_dev *dev,
> -                                     uint64_t *features)
> +                                   uint64_t *features)
>   {
>       int ret;
>   
>       ret = vhost_vdpa_call(dev, VHOST_GET_FEATURES, features);
>       trace_vhost_vdpa_get_features(dev, *features);
> +
> +    if (ret == 0) {
> +        struct vhost_vdpa *v = dev->opaque;
> +        v->host_features = *features;
> +    }
>       return ret;
>   }
>