Re: [PATCH v3 2/5] vdpa: add vhost_vdpa_reset_status_fd

[Jason Wang <jasowang@redhat.com>]

On Tue, May 9, 2023 at 11:44 PM Eugenio Pérez <eperezma@redhat.com> wrote:
>
> This allows to reset a vhost-vdpa device from external subsystems like
> vhost-net, since it does not have any struct vhost_dev by the time we
> need to use it.
>
> It is used in subsequent patches to negotiate features
> and probe for CVQ ASID isolation.
>
> Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
> Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
> ---
>  include/hw/virtio/vhost-vdpa.h |  1 +
>  hw/virtio/vhost-vdpa.c         | 58 +++++++++++++++++++++++-----------
>  2 files changed, 41 insertions(+), 18 deletions(-)
>
> diff --git a/include/hw/virtio/vhost-vdpa.h b/include/hw/virtio/vhost-vdpa.h
> index c278a2a8de..28de7da91e 100644
> --- a/include/hw/virtio/vhost-vdpa.h
> +++ b/include/hw/virtio/vhost-vdpa.h
> @@ -54,6 +54,7 @@ typedef struct vhost_vdpa {
>      VhostVDPAHostNotifier notifier[VIRTIO_QUEUE_MAX];
>  } VhostVDPA;
>
> +void vhost_vdpa_reset_status_fd(int fd);
>  int vhost_vdpa_get_iova_range(int fd, struct vhost_vdpa_iova_range *iova_range);
>
>  int vhost_vdpa_dma_map(struct vhost_vdpa *v, uint32_t asid, hwaddr iova,
> diff --git a/hw/virtio/vhost-vdpa.c b/hw/virtio/vhost-vdpa.c
> index bbabea18f3..7a2053b8d9 100644
> --- a/hw/virtio/vhost-vdpa.c
> +++ b/hw/virtio/vhost-vdpa.c
> @@ -335,38 +335,45 @@ static const MemoryListener vhost_vdpa_memory_listener = {
>      .region_del = vhost_vdpa_listener_region_del,
>  };
>
> -static int vhost_vdpa_call(struct vhost_dev *dev, unsigned long int request,
> -                             void *arg)
> +static int vhost_vdpa_dev_fd(const struct vhost_dev *dev)
>  {
>      struct vhost_vdpa *v = dev->opaque;
> -    int fd = v->device_fd;
> -    int ret;
>
>      assert(dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_VDPA);
> +    return v->device_fd;
> +}

Nit: unless the vhost_dev structure is opaque to the upper layer, I
don't see any advantage for having a dedicated indirect helper to get
device_fd.

> +
> +static int vhost_vdpa_call_fd(int fd, unsigned long int request, void *arg)
> +{
> +    int ret = ioctl(fd, request, arg);
>
> -    ret = ioctl(fd, request, arg);
>      return ret < 0 ? -errno : ret;
>  }
>
> -static int vhost_vdpa_add_status(struct vhost_dev *dev, uint8_t status)
> +static int vhost_vdpa_call(struct vhost_dev *dev, unsigned long int request,
> +                           void *arg)
> +{
> +    return vhost_vdpa_call_fd(vhost_vdpa_dev_fd(dev), request, arg);
> +}
> +
> +static int vhost_vdpa_add_status_fd(int fd, uint8_t status)
>  {
>      uint8_t s;
>      int ret;
>
> -    trace_vhost_vdpa_add_status(dev, status);
> -    ret = vhost_vdpa_call(dev, VHOST_VDPA_GET_STATUS, &s);
> +    ret = vhost_vdpa_call_fd(fd, VHOST_VDPA_GET_STATUS, &s);
>      if (ret < 0) {
>          return ret;
>      }
>
>      s |= status;
>
> -    ret = vhost_vdpa_call(dev, VHOST_VDPA_SET_STATUS, &s);
> +    ret = vhost_vdpa_call_fd(fd, VHOST_VDPA_SET_STATUS, &s);
>      if (ret < 0) {
>          return ret;
>      }
>
> -    ret = vhost_vdpa_call(dev, VHOST_VDPA_GET_STATUS, &s);
> +    ret = vhost_vdpa_call_fd(fd, VHOST_VDPA_GET_STATUS, &s);
>      if (ret < 0) {
>          return ret;
>      }
> @@ -378,6 +385,12 @@ static int vhost_vdpa_add_status(struct vhost_dev *dev, uint8_t status)
>      return 0;
>  }
>
> +static int vhost_vdpa_add_status(struct vhost_dev *dev, uint8_t status)
> +{
> +    trace_vhost_vdpa_add_status(dev, status);
> +    return vhost_vdpa_add_status_fd(vhost_vdpa_dev_fd(dev), status);
> +}
> +
>  int vhost_vdpa_get_iova_range(int fd, struct vhost_vdpa_iova_range *iova_range)
>  {
>      int ret = ioctl(fd, VHOST_VDPA_GET_IOVA_RANGE, iova_range);
> @@ -709,16 +722,20 @@ static int vhost_vdpa_get_device_id(struct vhost_dev *dev,
>      return ret;
>  }
>
> +static int vhost_vdpa_reset_device_fd(int fd)
> +{
> +    uint8_t status = 0;
> +
> +    return vhost_vdpa_call_fd(fd, VHOST_VDPA_SET_STATUS, &status);
> +}
> +
>  static int vhost_vdpa_reset_device(struct vhost_dev *dev)
>  {
>      struct vhost_vdpa *v = dev->opaque;
> -    int ret;
> -    uint8_t status = 0;
>
> -    ret = vhost_vdpa_call(dev, VHOST_VDPA_SET_STATUS, &status);
> -    trace_vhost_vdpa_reset_device(dev);
>      v->suspended = false;
> -    return ret;
> +    trace_vhost_vdpa_reset_device(dev);
> +    return vhost_vdpa_reset_device_fd(vhost_vdpa_dev_fd(dev));
>  }
>
>  static int vhost_vdpa_get_vq_index(struct vhost_dev *dev, int idx)
> @@ -1170,6 +1187,13 @@ static int vhost_vdpa_dev_start(struct vhost_dev *dev, bool started)
>      return 0;
>  }
>
> +void vhost_vdpa_reset_status_fd(int fd)
> +{
> +    vhost_vdpa_reset_device_fd(fd);
> +    vhost_vdpa_add_status_fd(fd, VIRTIO_CONFIG_S_ACKNOWLEDGE |
> +                                 VIRTIO_CONFIG_S_DRIVER);

I would like to rename this function since it does more than just reset.

Thanks

> +}
> +
>  static void vhost_vdpa_reset_status(struct vhost_dev *dev)
>  {
>      struct vhost_vdpa *v = dev->opaque;
> @@ -1178,9 +1202,7 @@ static void vhost_vdpa_reset_status(struct vhost_dev *dev)
>          return;
>      }
>
> -    vhost_vdpa_reset_device(dev);
> -    vhost_vdpa_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE |
> -                               VIRTIO_CONFIG_S_DRIVER);
> +    vhost_vdpa_reset_status_fd(vhost_vdpa_dev_fd(dev));
>      memory_listener_unregister(&v->listener);
>  }
>
> --
> 2.31.1
>