Make it possible for the application to determine whether the AF_XDP
socket is running in zero-copy mode. To achieve this, add a new
getsockopt option XDP_OPTIONS that returns flags. The only flag
supported for now is the zero-copy mode indicator.
Also query XDP_OPTIONS in the xdpsock sample application. The zero-copy
flag will be used in the following commits.
Signed-off-by: Maxim Mikityanskiy <maxi...@mellanox.com>
---
include/uapi/linux/if_xdp.h | 7 +++++++
net/xdp/xsk.c | 22 ++++++++++++++++++++++
tools/include/uapi/linux/if_xdp.h | 7 +++++++
tools/lib/bpf/xsk.c | 11 +++++++++++
4 files changed, 47 insertions(+)
diff --git a/include/uapi/linux/if_xdp.h b/include/uapi/linux/if_xdp.h
index caed8b1614ff..9ae4b4e08b68 100644
--- a/include/uapi/linux/if_xdp.h
+++ b/include/uapi/linux/if_xdp.h
@@ -46,6 +46,7 @@ struct xdp_mmap_offsets {
#define XDP_UMEM_FILL_RING 5
#define XDP_UMEM_COMPLETION_RING 6
#define XDP_STATISTICS 7
+#define XDP_OPTIONS 8
struct xdp_umem_reg {
__u64 addr; /* Start of packet data area */
@@ -60,6 +61,12 @@ struct xdp_statistics {
__u64 tx_invalid_descs; /* Dropped due to invalid descriptor */
};
+struct xdp_options {
+ __u32 flags;
+};
+
+#define XDP_OPTIONS_FLAG_ZEROCOPY (1 << 0)
+
/* Pgoff for mmaping the rings */
#define XDP_PGOFF_RX_RING 0
#define XDP_PGOFF_TX_RING 0x80000000
diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
index ca764ed9da41..ff8427552e8d 100644
--- a/net/xdp/xsk.c
+++ b/net/xdp/xsk.c
@@ -652,6 +652,28 @@ static int xsk_getsockopt(struct socket *sock, int level,
int optname,
return 0;
}
+ case XDP_OPTIONS:
+ {
+ struct xdp_options opts;
+
+ if (len < sizeof(opts))
+ return -EINVAL;
+
+ opts.flags = 0;
+
+ mutex_lock(&xs->mutex);
+ if (xs->zc)
+ opts.flags |= XDP_OPTIONS_FLAG_ZEROCOPY;
+ mutex_unlock(&xs->mutex);
+
+ len = sizeof(opts);
+ if (copy_to_user(optval, &opts, len))
+ return -EFAULT;
+ if (put_user(len, optlen))
+ return -EFAULT;
+
+ return 0;
+ }
default:
break;
}
diff --git a/tools/include/uapi/linux/if_xdp.h
b/tools/include/uapi/linux/if_xdp.h
index caed8b1614ff..9ae4b4e08b68 100644
--- a/tools/include/uapi/linux/if_xdp.h
+++ b/tools/include/uapi/linux/if_xdp.h
@@ -46,6 +46,7 @@ struct xdp_mmap_offsets {
#define XDP_UMEM_FILL_RING 5
#define XDP_UMEM_COMPLETION_RING 6
#define XDP_STATISTICS 7
+#define XDP_OPTIONS 8
struct xdp_umem_reg {
__u64 addr; /* Start of packet data area */
@@ -60,6 +61,12 @@ struct xdp_statistics {
__u64 tx_invalid_descs; /* Dropped due to invalid descriptor */
};
+struct xdp_options {
+ __u32 flags;
+};
+
+#define XDP_OPTIONS_FLAG_ZEROCOPY (1 << 0)
+
/* Pgoff for mmaping the rings */
#define XDP_PGOFF_RX_RING 0
#define XDP_PGOFF_TX_RING 0x80000000
diff --git a/tools/lib/bpf/xsk.c b/tools/lib/bpf/xsk.c
index 8d0078b65486..50d7235e3b21 100644
--- a/tools/lib/bpf/xsk.c
+++ b/tools/lib/bpf/xsk.c
@@ -67,6 +67,7 @@ struct xsk_socket {
int xsks_map_fd;
__u32 queue_id;
char ifname[IFNAMSIZ];
+ bool zc;
};
struct xsk_nl_info {
@@ -525,6 +526,7 @@ int xsk_socket__create(struct xsk_socket **xsk_ptr, const
char *ifname,
{
struct sockaddr_xdp sxdp = {};
struct xdp_mmap_offsets off;
+ struct xdp_options opts;
struct xsk_socket *xsk;
socklen_t optlen;
void *map;
@@ -642,6 +644,15 @@ int xsk_socket__create(struct xsk_socket **xsk_ptr, const
char *ifname,
goto out_mmap_tx;
}
+ optlen = sizeof(opts);
+ err = getsockopt(xsk->fd, SOL_XDP, XDP_OPTIONS, &opts, &optlen);
+ if (err) {
+ err = -errno;
+ goto out_mmap_tx;
+ }
+
+ xsk->zc = opts.flags & XDP_OPTIONS_FLAG_ZEROCOPY;
+
if (!(xsk->config.libbpf_flags & XSK_LIBBPF_FLAGS__INHIBIT_PROG_LOAD)) {
err = xsk_setup_xdp_prog(xsk);
if (err)
--
2.19.1
