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 <redacted>
Signed-off-by: Ciara Loftus <redacted>
---
 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