From: Arthur Fabre <afabre@xxxxxxxxxxxxxx>
xdp_buff stores whether metadata is supported by a NIC by setting
data_meta to be greater than data.
But xdp_frame only stores the metadata size (as metasize), so converting
between xdp_frame and xdp_buff is lossy.
Steal an unused bit in xdp_frame to track whether metadata is supported
or not.
This will lets us have "generic" functions for setting skb fields from
either xdp_frame or xdp_buff from drivers.
Signed-off-by: Arthur Fabre <afabre@xxxxxxxxxxxxxx>
---
include/net/xdp.h | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/include/net/xdp.h b/include/net/xdp.h
index 58019fa299b56dbd45c104fdfa807f73af6e4fa4..84afe07d09efdb2ab0cb78b904f02cb74f9a56b6 100644
--- a/include/net/xdp.h
+++ b/include/net/xdp.h
@@ -116,6 +116,9 @@ static __always_inline void xdp_buff_set_frag_pfmemalloc(struct xdp_buff *xdp)
xdp->flags |= XDP_FLAGS_FRAGS_PF_MEMALLOC;
}
+static bool xdp_data_meta_unsupported(const struct xdp_buff *xdp);
+static void xdp_set_data_meta_invalid(struct xdp_buff *xdp);
+
static __always_inline void *xdp_buff_traits(const struct xdp_buff *xdp)
{
return xdp->data_hard_start + _XDP_FRAME_SIZE;
@@ -270,7 +273,9 @@ struct xdp_frame {
void *data;
u32 len;
u32 headroom;
- u32 metasize; /* uses lower 8-bits */
+ u32 :23, /* unused */
+ meta_unsupported:1,
+ metasize:8;
/* Lifetime of xdp_rxq_info is limited to NAPI/enqueue time,
* while mem_type is valid on remote CPU.
*/
@@ -369,6 +374,8 @@ void xdp_convert_frame_to_buff(const struct xdp_frame *frame,
xdp->data = frame->data;
xdp->data_end = frame->data + frame->len;
xdp->data_meta = frame->data - frame->metasize;
+ if (frame->meta_unsupported)
+ xdp_set_data_meta_invalid(xdp);
xdp->frame_sz = frame->frame_sz;
xdp->flags = frame->flags;
}
@@ -396,6 +403,7 @@ int xdp_update_frame_from_buff(const struct xdp_buff *xdp,
xdp_frame->len = xdp->data_end - xdp->data;
xdp_frame->headroom = headroom - sizeof(*xdp_frame);
xdp_frame->metasize = metasize;
+ xdp_frame->meta_unsupported = xdp_data_meta_unsupported(xdp);
xdp_frame->frame_sz = xdp->frame_sz;
xdp_frame->flags = xdp->flags;
--
2.43.0
