On Thu, Apr 08, 2021 at 04:26:48PM +0800, Jason Wang wrote:
> This patch mandates 1.0 for vDPA devices. The goal is to have the
> semantic of normative statement in the virtio spec and eliminate the
> burden of transitional device for both vDPA bus and vDPA parent.
>
> uAPI seems fine since all the vDPA parent mandates
> VIRTIO_F_ACCESS_PLATFORM which implies 1.0 devices.
>
> For legacy guests, it can still work since Qemu will mediate when
> necessary (e.g doing the endian conversion).
>
> Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
Hmm. If we do this, don't we still have a problem with
legacy drivers which don't ack 1.0?
Note 1.0 affects ring endianness which is not mediated in QEMU
so QEMU can't pretend to device guest is 1.0.
> ---
> include/linux/vdpa.h | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/include/linux/vdpa.h b/include/linux/vdpa.h
> index 0fefeb976877..cfde4ec999b4 100644
> --- a/include/linux/vdpa.h
> +++ b/include/linux/vdpa.h
> @@ -6,6 +6,7 @@
> #include <linux/device.h>
> #include <linux/interrupt.h>
> #include <linux/vhost_iotlb.h>
> +#include <uapi/linux/virtio_config.h>
>
> /**
> * vDPA callback definition.
> @@ -317,6 +318,11 @@ static inline int vdpa_set_features(struct vdpa_device *vdev, u64 features)
> {
> const struct vdpa_config_ops *ops = vdev->config;
>
> + /* Mandating 1.0 to have semantics of normative statements in
> + * the spec. */
> + if (!(features & BIT_ULL(VIRTIO_F_VERSION_1)))
> + return -EINVAL;
> +
> vdev->features_valid = true;
> return ops->set_features(vdev, features);
> }
> --
> 2.25.1
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