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SubjectRe: [PATCH net-next v3 01/13] virtio: add packed ring types and macros
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On 2018/11/21 下午6:03, Tiwei Bie wrote:
> Add types and macros for packed ring.
>
> Signed-off-by: Tiwei Bie <tiwei.bie@intel.com>
> ---
> include/uapi/linux/virtio_config.h | 3 +++
> include/uapi/linux/virtio_ring.h | 52 ++++++++++++++++++++++++++++++++++++++
> 2 files changed, 55 insertions(+)
>
> diff --git a/include/uapi/linux/virtio_config.h b/include/uapi/linux/virtio_config.h
> index 449132c76b1c..1196e1c1d4f6 100644
> --- a/include/uapi/linux/virtio_config.h
> +++ b/include/uapi/linux/virtio_config.h
> @@ -75,6 +75,9 @@
> */
> #define VIRTIO_F_IOMMU_PLATFORM 33
>
> +/* This feature indicates support for the packed virtqueue layout. */
> +#define VIRTIO_F_RING_PACKED 34
> +
> /*
> * Does the device support Single Root I/O Virtualization?
> */
> diff --git a/include/uapi/linux/virtio_ring.h b/include/uapi/linux/virtio_ring.h
> index 6d5d5faa989b..2414f8af26b3 100644
> --- a/include/uapi/linux/virtio_ring.h
> +++ b/include/uapi/linux/virtio_ring.h
> @@ -44,6 +44,13 @@
> /* This means the buffer contains a list of buffer descriptors. */
> #define VRING_DESC_F_INDIRECT 4
>
> +/*
> + * Mark a descriptor as available or used in packed ring.
> + * Notice: they are defined as shifts instead of shifted values.


This looks inconsistent to previous flags, any reason for using shifts?


> + */
> +#define VRING_PACKED_DESC_F_AVAIL 7
> +#define VRING_PACKED_DESC_F_USED 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. */
> @@ -53,6 +60,23 @@
> * optimization. */
> #define VRING_AVAIL_F_NO_INTERRUPT 1
>
> +/* Enable events in packed ring. */
> +#define VRING_PACKED_EVENT_FLAG_ENABLE 0x0
> +/* Disable events in packed ring. */
> +#define VRING_PACKED_EVENT_FLAG_DISABLE 0x1
> +/*
> + * Enable events for a specific descriptor in packed ring.
> + * (as specified by Descriptor Ring Change Event Offset/Wrap Counter).
> + * Only valid if VIRTIO_RING_F_EVENT_IDX has been negotiated.
> + */
> +#define VRING_PACKED_EVENT_FLAG_DESC 0x2


Any reason for using _FLAG_ instead of _F_?

Thanks


> +
> +/*
> + * Wrap counter bit shift in event suppression structure
> + * of packed ring.
> + */
> +#define VRING_PACKED_EVENT_F_WRAP_CTR 15
> +
> /* We support indirect buffer descriptors */
> #define VIRTIO_RING_F_INDIRECT_DESC 28
>
> @@ -171,4 +195,32 @@ static inline int vring_need_event(__u16 event_idx, __u16 new_idx, __u16 old)
> return (__u16)(new_idx - event_idx - 1) < (__u16)(new_idx - old);
> }
>
> +struct vring_packed_desc_event {
> + /* Descriptor Ring Change Event Offset/Wrap Counter. */
> + __le16 off_wrap;
> + /* Descriptor Ring Change Event Flags. */
> + __le16 flags;
> +};
> +
> +struct vring_packed_desc {
> + /* Buffer Address. */
> + __le64 addr;
> + /* Buffer Length. */
> + __le32 len;
> + /* Buffer ID. */
> + __le16 id;
> + /* The flags depending on descriptor type. */
> + __le16 flags;
> +};
> +
> +struct vring_packed {
> + unsigned int num;
> +
> + struct vring_packed_desc *desc;
> +
> + struct vring_packed_desc_event *driver;
> +
> + struct vring_packed_desc_event *device;
> +};
> +
> #endif /* _UAPI_LINUX_VIRTIO_RING_H */

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