On Fri, Nov 30, 2018 at 02:01:06PM +0100, Maxime Coquelin wrote: > > > 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 下午6:03, Tiwei Bie wrote: > > > > > Add types and macros for packed ring. > > > > > > > > > > Signed-off-by: Tiwei Bie <tiwei.bie@xxxxxxxxx> > > > > > --- > > > > > 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/#1989390 > > > > But 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. I don't think that will help. the problem is that most of the existing virtio code consistently uses _F_ as shifts. So we just need to do something about these 5 being inconsistent: include/uapi/linux/virtio_ring.h:#define VRING_DESC_F_NEXT 1 include/uapi/linux/virtio_ring.h:#define VRING_DESC_F_WRITE 2 include/uapi/linux/virtio_ring.h:#define VRING_DESC_F_INDIRECT 4 include/uapi/linux/virtio_ring.h:#define VRING_USED_F_NO_NOTIFY 1 include/uapi/linux/virtio_ring.h:#define VRING_AVAIL_F_NO_INTERRUPT 1 I do not want all of virtio to become verbose with _SHIFT, ergo we need to change the above 5 to have names which are with _F_ and have the bit number. > > > > > > > > > > > > > > > > > + */ > > > > > +#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_? > > > > > > Yeah, it was suggested to not use _F_, as these are values, > > > should not have _F_: > > > > > > https://patchwork.ozlabs.org/patch/942296/#1989390 > > > > > > Regards, > > > Tiwei > > > > > > > > > > > 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 */ _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
