Re: [PATCH v5 04/23] vhost: move protocol_features to vhost_user

["Michael S. Tsirkin" <mst@redhat.com>]

On Fri, Feb 06, 2026 at 12:52:38PM +0300, Vladimir Sementsov-Ogievskiy wrote:
> As comment says: it's only for vhost-user. So, let's move it
> to corresponding vhost backend realization.
> 
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>


breaks build:

https://gitlab.com/mstredhat/qemu/-/jobs/13201554836

builds/mstredhat/qemu/build/../hw/virtio/virtio-qmp.c:830:(.text+0xd60): undefined reference to `vhost_user_qmp_status'


> ---
>  backends/cryptodev-vhost.c     |  1 -
>  hw/block/vhost-user-blk.c      |  6 ++----
>  hw/net/vhost_net.c             |  2 --
>  hw/virtio/vhost-user.c         | 36 +++++++++++++++++++++++++++-------
>  hw/virtio/virtio-qmp.c         |  6 ++++--
>  include/hw/virtio/vhost-user.h |  4 ++++
>  include/hw/virtio/vhost.h      |  8 --------
>  7 files changed, 39 insertions(+), 24 deletions(-)
> 
> diff --git a/backends/cryptodev-vhost.c b/backends/cryptodev-vhost.c
> index abdfce33af..c6069f4e5b 100644
> --- a/backends/cryptodev-vhost.c
> +++ b/backends/cryptodev-vhost.c
> @@ -60,7 +60,6 @@ cryptodev_vhost_init(
>  
>      crypto->cc = options->cc;
>  
> -    crypto->dev.protocol_features = 0;
>      crypto->backend = -1;
>  
>      /* vhost-user needs vq_index to initiate a specific queue pair */
> diff --git a/hw/block/vhost-user-blk.c b/hw/block/vhost-user-blk.c
> index dc99de0263..2831f3c053 100644
> --- a/hw/block/vhost-user-blk.c
> +++ b/hw/block/vhost-user-blk.c
> @@ -572,10 +572,8 @@ static bool vhost_user_blk_inflight_needed(void *opaque)
>  {
>      struct VHostUserBlk *s = opaque;
>  
> -    bool inflight_migration = virtio_has_feature(s->dev.protocol_features,
> -                               VHOST_USER_PROTOCOL_F_GET_VRING_BASE_INFLIGHT);
> -
> -    return inflight_migration;
> +    return vhost_user_has_protocol_feature(
> +        &s->dev, VHOST_USER_PROTOCOL_F_GET_VRING_BASE_INFLIGHT);
>  }
>  
>  static const VMStateDescription vmstate_vhost_user_blk_inflight = {
> diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c
> index fda90e231e..ca19983126 100644
> --- a/hw/net/vhost_net.c
> +++ b/hw/net/vhost_net.c
> @@ -265,9 +265,7 @@ struct vhost_net *vhost_net_init(VhostNetOptions *options)
>              goto fail;
>          }
>          net->backend = r;
> -        net->dev.protocol_features = 0;
>      } else {
> -        net->dev.protocol_features = 0;
>          net->backend = -1;
>  
>          /* vhost-user needs vq_index to initiate a specific queue pair */
> diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
> index 2de82ac466..de8ead3e94 100644
> --- a/hw/virtio/vhost-user.c
> +++ b/hw/virtio/vhost-user.c
> @@ -11,6 +11,7 @@
>  #include "qemu/osdep.h"
>  #include "qapi/error.h"
>  #include "hw/virtio/virtio-dmabuf.h"
> +#include "hw/virtio/virtio-qmp.h"
>  #include "hw/virtio/vhost.h"
>  #include "hw/virtio/virtio-crypto.h"
>  #include "hw/virtio/vhost-user.h"
> @@ -264,6 +265,14 @@ struct vhost_user {
>      /* Our current regions */
>      int num_shadow_regions;
>      struct vhost_memory_region shadow_regions[VHOST_USER_MAX_RAM_SLOTS];
> +
> +    /**
> +     * @protocol_features: the vhost-user protocol feature set by
> +     * VHOST_USER_SET_PROTOCOL_FEATURES. Protocol features are only
> +     * negotiated if VHOST_USER_F_PROTOCOL_FEATURES has been offered
> +     * by the backend (see @features).
> +     */
> +    uint64_t protocol_features;
>  };
>  
>  struct scrub_regions {
> @@ -272,10 +281,13 @@ struct scrub_regions {
>      int fd_idx;
>  };
>  
> -static bool vhost_user_has_protocol_feature(struct vhost_dev *dev,
> -                                            uint64_t feature)
> +bool vhost_user_has_protocol_feature(struct vhost_dev *dev, uint64_t feature)
>  {
> -    return virtio_has_feature(dev->protocol_features, feature);
> +    struct vhost_user *u = dev->opaque;
> +
> +    assert(dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_USER);
> +
> +    return virtio_has_feature(u->protocol_features, feature);
>  }
>  
>  static int vhost_user_read_header(struct vhost_dev *dev, VhostUserMsg *msg)
> @@ -1343,8 +1355,8 @@ static int vhost_set_vring_file(struct vhost_dev *dev,
>      int ret;
>      int fds[VHOST_USER_MAX_RAM_SLOTS];
>      size_t fd_num = 0;
> -    bool reply_supported = virtio_has_feature(dev->protocol_features,
> -                                              VHOST_USER_PROTOCOL_F_REPLY_ACK);
> +    bool reply_supported =
> +        vhost_user_has_protocol_feature(dev, VHOST_USER_PROTOCOL_F_REPLY_ACK);
>      VhostUserMsg msg = {
>          .hdr.request = request,
>          .hdr.flags = VHOST_USER_VERSION,
> @@ -2244,8 +2256,8 @@ static int vhost_user_backend_init(struct vhost_dev *dev, void *opaque,
>          }
>  
>          /* final set of protocol features */
> -        dev->protocol_features = protocol_features;
> -        err = vhost_user_set_protocol_features(dev, dev->protocol_features);
> +        u->protocol_features = protocol_features;
> +        err = vhost_user_set_protocol_features(dev, u->protocol_features);
>          if (err < 0) {
>              error_setg_errno(errp, EPROTO, "vhost_backend_init failed");
>              return -EPROTO;
> @@ -3036,6 +3048,16 @@ static int vhost_user_check_device_state(struct vhost_dev *dev, Error **errp)
>      return 0;
>  }
>  
> +void vhost_user_qmp_status(struct vhost_dev *dev, VirtioStatus *status)
> +{
> +    struct vhost_user *u = dev->opaque;
> +
> +    assert(dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_USER);
> +
> +    status->vhost_dev->protocol_features =
> +        qmp_decode_protocols(u->protocol_features);
> +}
> +
>  const VhostOps user_ops = {
>          .backend_type = VHOST_BACKEND_TYPE_USER,
>          .vhost_backend_init = vhost_user_backend_init,
> diff --git a/hw/virtio/virtio-qmp.c b/hw/virtio/virtio-qmp.c
> index 916972e331..5e42b7b540 100644
> --- a/hw/virtio/virtio-qmp.c
> +++ b/hw/virtio/virtio-qmp.c
> @@ -821,12 +821,14 @@ VirtioStatus *qmp_x_query_virtio_status(const char *path, Error **errp)
>          status->vhost_dev->acked_features =
>              qmp_decode_features(vdev->device_id, hdev->acked_features_ex);
>  
> -        status->vhost_dev->protocol_features =
> -            qmp_decode_protocols(hdev->protocol_features);
>          status->vhost_dev->max_queues = hdev->max_queues;
>          status->vhost_dev->backend_cap = hdev->backend_cap;
>          status->vhost_dev->log_enabled = hdev->log_enabled;
>          status->vhost_dev->log_size = hdev->log_size;
> +
> +        if (hdev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_USER) {
> +            vhost_user_qmp_status(hdev, status);
> +        }
>      }
>  
>      return status;
> diff --git a/include/hw/virtio/vhost-user.h b/include/hw/virtio/vhost-user.h
> index 53fe996686..0e576fc538 100644
> --- a/include/hw/virtio/vhost-user.h
> +++ b/include/hw/virtio/vhost-user.h
> @@ -10,6 +10,7 @@
>  
>  #include "chardev/char-fe.h"
>  #include "hw/virtio/virtio.h"
> +#include "qapi/qapi-types-virtio.h"
>  
>  enum VhostUserProtocolFeature {
>      VHOST_USER_PROTOCOL_F_MQ = 0,
> @@ -113,4 +114,7 @@ void vhost_user_async_close(DeviceState *d,
>                              CharFrontend *chardev, struct vhost_dev *vhost,
>                              vu_async_close_fn cb);
>  
> +void vhost_user_qmp_status(struct vhost_dev *dev, VirtioStatus *status);
> +bool vhost_user_has_protocol_feature(struct vhost_dev *dev, uint64_t feature);
> +
>  #endif
> diff --git a/include/hw/virtio/vhost.h b/include/hw/virtio/vhost.h
> index e139e05985..4a9bd3effe 100644
> --- a/include/hw/virtio/vhost.h
> +++ b/include/hw/virtio/vhost.h
> @@ -104,14 +104,6 @@ struct vhost_dev {
>      VIRTIO_DECLARE_FEATURES(features);
>      VIRTIO_DECLARE_FEATURES(acked_features);
>  
> -    /**
> -     * @protocol_features: is the vhost-user only feature set by
> -     * VHOST_USER_SET_PROTOCOL_FEATURES. Protocol features are only
> -     * negotiated if VHOST_USER_F_PROTOCOL_FEATURES has been offered
> -     * by the backend (see @features).
> -     */
> -    uint64_t protocol_features;
> -
>      uint64_t max_queues;
>      uint64_t backend_cap;
>      /* @started: is the vhost device started? */
> -- 
> 2.52.0