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Subject: Re: [PATCH net-next v3 01/13] virtio: add packed ring types and macros
On 11/30/18 1:47 PM, Michael S. Tsirkin wrote:
On Fri, Nov 30, 2018 at 05:53:40PM +0800, Tiwei Bie wrote:On Fri, Nov 30, 2018 at 04:10:55PM +0800, Jason Wang wrote:On 2018/11/21 äå6:03, 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?Yeah, it was suggested to use shifts, as _F_ should be a bit number, not a shifted value: https://patchwork.ozlabs.org/patch/942296/#1989390But let's add a _SPLIT_ variant that uses shifts consistently.
Maybe we could avoid adding SPLIT and PACKED, but define as follow: #define VRING_DESC_F_INDIRECT_SHIFT 2 #define VRING_DESC_F_INDIRECT (1ull << VRING_DESC_F_INDIRECT_SHIFT) #define VRING_DESC_F_AVAIL_SHIFT 7 #define VRING_DESC_F_AVAIL (1ull << VRING_DESC_F_AVAIL_SHIFT) I think it would be better for consistency.
+ */ +#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 0x2Any reason for using _FLAG_ instead of _F_?Yeah, it was suggested to not use _F_, as these are values, should not have _F_: https://patchwork.ozlabs.org/patch/942296/#1989390 Regards, TiweiThanks+ +/* + * 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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