[PATCH 07/11] libbpf: add flags to umem config

[Kevin Laatz <kevin.laatz@xxxxxxxxx>]

This patch adds a 'flags' field to the umem_config and umem_reg structs.
This will allow for more options to be added for configuring umems.

The first use for the flags field is to add a flag for unaligned chunks
mode. These flags can either be user-provided or filled with a default.

Signed-off-by: Kevin Laatz <kevin.laatz@xxxxxxxxx>
Signed-off-by: Ciara Loftus <ciara.loftus@xxxxxxxxx>
---
 tools/include/uapi/linux/if_xdp.h | 4 ++++
 tools/lib/bpf/xsk.c               | 7 +++++++
 tools/lib/bpf/xsk.h               | 2 ++
 3 files changed, 13 insertions(+)

diff --git a/tools/include/uapi/linux/if_xdp.h b/tools/include/uapi/linux/if_xdp.h
index caed8b1614ff..8548f2110a77 100644
--- a/tools/include/uapi/linux/if_xdp.h
+++ b/tools/include/uapi/linux/if_xdp.h
@@ -17,6 +17,9 @@
 #define XDP_COPY	(1 << 1) /* Force copy-mode */
 #define XDP_ZEROCOPY	(1 << 2) /* Force zero-copy mode */
 
+/* Flags for xsk_umem_config flags */
+#define XDP_UMEM_UNALIGNED_CHUNKS (1 << 0)
+
 struct sockaddr_xdp {
 	__u16 sxdp_family;
 	__u16 sxdp_flags;
@@ -52,6 +55,7 @@ struct xdp_umem_reg {
 	__u64 len; /* Length of packet data area */
 	__u32 chunk_size;
 	__u32 headroom;
+	__u32 flags;
 };
 
 struct xdp_statistics {
diff --git a/tools/lib/bpf/xsk.c b/tools/lib/bpf/xsk.c
index 7ef6293b4fd7..df4207d4ff4a 100644
--- a/tools/lib/bpf/xsk.c
+++ b/tools/lib/bpf/xsk.c
@@ -115,6 +115,7 @@ static void xsk_set_umem_config(struct xsk_umem_config *cfg,
 		cfg->comp_size = XSK_RING_CONS__DEFAULT_NUM_DESCS;
 		cfg->frame_size = XSK_UMEM__DEFAULT_FRAME_SIZE;
 		cfg->frame_headroom = XSK_UMEM__DEFAULT_FRAME_HEADROOM;
+		cfg->flags = XSK_UMEM__DEFAULT_FLAGS;
 		return;
 	}
 
@@ -122,6 +123,7 @@ static void xsk_set_umem_config(struct xsk_umem_config *cfg,
 	cfg->comp_size = usr_cfg->comp_size;
 	cfg->frame_size = usr_cfg->frame_size;
 	cfg->frame_headroom = usr_cfg->frame_headroom;
+	cfg->flags = usr_cfg->flags;
 }
 
 static int xsk_set_xdp_socket_config(struct xsk_socket_config *cfg,
@@ -181,6 +183,11 @@ int xsk_umem__create(struct xsk_umem **umem_ptr, void *umem_area, __u64 size,
 	mr.len = size;
 	mr.chunk_size = umem->config.frame_size;
 	mr.headroom = umem->config.frame_headroom;
+	mr.flags = umem->config.flags;
+
+	/* Headroom must be 0 for unaligned chunks */
+	if ((mr.flags & XDP_UMEM_UNALIGNED_CHUNKS) && mr.headroom != 0)
+		return -EINVAL;
 
 	err = setsockopt(umem->fd, SOL_XDP, XDP_UMEM_REG, &mr, sizeof(mr));
 	if (err) {
diff --git a/tools/lib/bpf/xsk.h b/tools/lib/bpf/xsk.h
index 82ea71a0f3ec..8d393873b70f 100644
--- a/tools/lib/bpf/xsk.h
+++ b/tools/lib/bpf/xsk.h
@@ -170,12 +170,14 @@ LIBBPF_API int xsk_socket__fd(const struct xsk_socket *xsk);
 #define XSK_UMEM__DEFAULT_FRAME_SHIFT    11 /* 2048 bytes */
 #define XSK_UMEM__DEFAULT_FRAME_SIZE     (1 << XSK_UMEM__DEFAULT_FRAME_SHIFT)
 #define XSK_UMEM__DEFAULT_FRAME_HEADROOM 0
+#define XSK_UMEM__DEFAULT_FLAGS 0
 
 struct xsk_umem_config {
 	__u32 fill_size;
 	__u32 comp_size;
 	__u32 frame_size;
 	__u32 frame_headroom;
+	__u32 flags;
 };
 
 /* Flags for the libbpf_flags field. */
-- 
2.17.1