Re: [PATCH RFC 1/2] virtio: introduce packed ring defines

[Jens Freimann]

On Fri, Feb 23, 2018 at 07:18:00PM +0800, Tiwei Bie wrote:
> Signed-off-by: Tiwei Bie <tiwei.bie@xxxxxxxxx>
> ---
> include/uapi/linux/virtio_config.h | 18 +++++++++-
> include/uapi/linux/virtio_ring.h   | 68 ++++++++++++++++++++++++++++++++++++++
> 2 files changed, 85 insertions(+), 1 deletion(-)
>
> diff --git a/include/uapi/linux/virtio_config.h b/include/uapi/linux/virtio_config.h
> index 308e2096291f..e3d077ef5207 100644
> --- a/include/uapi/linux/virtio_config.h
> +++ b/include/uapi/linux/virtio_config.h
> @@ -49,7 +49,7 @@
>  * transport being used (eg. virtio_ring), the rest are per-device feature
>  * bits. */
> #define VIRTIO_TRANSPORT_F_START	28
> -#define VIRTIO_TRANSPORT_F_END		34
> +#define VIRTIO_TRANSPORT_F_END		37
>
> #ifndef VIRTIO_CONFIG_NO_LEGACY
> /* Do we get callbacks when the ring is completely used, even if we've
> @@ -71,4 +71,20 @@
>  * this is for compatibility with legacy systems.
>  */
> #define VIRTIO_F_IOMMU_PLATFORM		33
> +
> +/* This feature indicates support for the packed virtqueue layout. */
> +#define VIRTIO_F_RING_PACKED		34

Spec says VIRTIO_F_PACKED_RING not RING_PACKED
> +
> +/*
> + * This feature indicates that all buffers are used by the device
> + * in the same order in which they have been made available.
> + */
> +#define VIRTIO_F_IN_ORDER		35
> +
> +/*
> + * This feature indicates that drivers pass extra data (besides
> + * identifying the Virtqueue) in their device notifications.
> + */
> +#define VIRTIO_F_NOTIFICATION_DATA	36
> +
> #endif /* _UAPI_LINUX_VIRTIO_CONFIG_H */
> diff --git a/include/uapi/linux/virtio_ring.h b/include/uapi/linux/virtio_ring.h
> index 6d5d5faa989b..77b1d4aeef72 100644
> --- a/include/uapi/linux/virtio_ring.h
> +++ b/include/uapi/linux/virtio_ring.h
> @@ -44,6 +44,9 @@
> /* This means the buffer contains a list of buffer descriptors. */
> #define VRING_DESC_F_INDIRECT	4
>
> +#define VRING_DESC_F_AVAIL(b)	((b) << 7)
> +#define VRING_DESC_F_USED(b)	((b) << 15)
> +
> /* The Host uses this in used->flags to advise the Guest: don't kick me when
>  * you add a buffer.  It's unreliable, so it's simply an optimization.  Guest
>  * will still kick if it's out of buffers. */
> @@ -104,6 +107,36 @@ struct vring {
> 	struct vring_used *used;
> };
>
> +struct vring_packed_desc_event {
> +	/* Descriptor Event Offset */
> +	__virtio16 desc_event_off   : 15,
> +	/* Descriptor Event Wrap Counter */
> +		   desc_event_wrap  : 1;
> +	/* Descriptor Event Flags */
> +	__virtio16 desc_event_flags : 2;
> +};

Where would the virtqueue number go in driver notifications?

regards,
Jens