selftests/xsk: load and attach XDP program only once per mode

Load and attach the XDP program only once per XDP mode that is being
executed. Today, the XDP program is loaded and attached for every
test, then unloaded, which takes a long time on real NICs, since they
have to reconfigure their HW, in contrast to veth. The test suite now
completes in 21 seconds, instead of 207 seconds previously on my
machine. This is a speed-up of around 10x.

This is accomplished by moving the XDP loading from the worker threads
to the main thread and replacing the XDP loading interfaces of xsk.c
that was taken from the xsk support in libbpf, with something more
explicit that is more useful for these tests. Instead, the relevant
file descriptors and ifindexes are just passed down to the new
functions.

Signed-off-by: Magnus Karlsson <magnus.karlsson@intel.com>
Acked-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Link: https://lore.kernel.org/r/20230111093526.11682-10-magnus.karlsson@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 61 insertions, 31 deletions

diff --git a/tools/testing/selftests/bpf/xsk.c b/tools/testing/selftests/bpf/xsk.c
index b166edfff86d..1dd953541812 100644
--- a/tools/testing/selftests/bpf/xsk.c
+++ b/tools/testing/selftests/bpf/xsk.c
@@ -51,6 +51,8 @@
 
 #define pr_warn(fmt, ...) fprintf(stderr, fmt, ##__VA_ARGS__)
 
+#define XSKMAP_SIZE 1
+
 enum xsk_prog {
 	XSK_PROG_FALLBACK,
 	XSK_PROG_REDIRECT_FLAGS,
@@ -387,10 +389,9 @@ static enum xsk_prog get_xsk_prog(void)
 	return detected;
 }
 
-static int xsk_load_xdp_prog(struct xsk_socket *xsk)
+static int __xsk_load_xdp_prog(int xsk_map_fd)
 {
 	static const int log_buf_size = 16 * 1024;
-	struct xsk_ctx *ctx = xsk->ctx;
 	char log_buf[log_buf_size];
 	int prog_fd;
 
@@ -418,7 +419,7 @@ static int xsk_load_xdp_prog(struct xsk_socket *xsk)
 		/* *(u32 *)(r10 - 4) = r2 */
 		BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_2, -4),
 		/* r1 = xskmap[] */
-		BPF_LD_MAP_FD(BPF_REG_1, ctx->xsks_map_fd),
+		BPF_LD_MAP_FD(BPF_REG_1, xsk_map_fd),
 		/* r3 = XDP_PASS */
 		BPF_MOV64_IMM(BPF_REG_3, 2),
 		/* call bpf_redirect_map */
@@ -430,7 +431,7 @@ static int xsk_load_xdp_prog(struct xsk_socket *xsk)
 		/* r2 += -4 */
 		BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -4),
 		/* r1 = xskmap[] */
-		BPF_LD_MAP_FD(BPF_REG_1, ctx->xsks_map_fd),
+		BPF_LD_MAP_FD(BPF_REG_1, xsk_map_fd),
 		/* call bpf_map_lookup_elem */
 		BPF_EMIT_CALL(BPF_FUNC_map_lookup_elem),
 		/* r1 = r0 */
@@ -442,7 +443,7 @@ static int xsk_load_xdp_prog(struct xsk_socket *xsk)
 		/* r2 = *(u32 *)(r10 - 4) */
 		BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_10, -4),
 		/* r1 = xskmap[] */
-		BPF_LD_MAP_FD(BPF_REG_1, ctx->xsks_map_fd),
+		BPF_LD_MAP_FD(BPF_REG_1, xsk_map_fd),
 		/* r3 = 0 */
 		BPF_MOV64_IMM(BPF_REG_3, 0),
 		/* call bpf_redirect_map */
@@ -461,7 +462,7 @@ static int xsk_load_xdp_prog(struct xsk_socket *xsk)
 		/* r2 = *(u32 *)(r1 + 16) */
 		BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1, 16),
 		/* r1 = xskmap[] */
-		BPF_LD_MAP_FD(BPF_REG_1, ctx->xsks_map_fd),
+		BPF_LD_MAP_FD(BPF_REG_1, xsk_map_fd),
 		/* r3 = XDP_PASS */
 		BPF_MOV64_IMM(BPF_REG_3, 2),
 		/* call bpf_redirect_map */
@@ -480,13 +481,40 @@ static int xsk_load_xdp_prog(struct xsk_socket *xsk)
 
 	prog_fd = bpf_prog_load(BPF_PROG_TYPE_XDP, NULL, "LGPL-2.1 or BSD-2-Clause",
 				progs[option], insns_cnt[option], &opts);
-	if (prog_fd < 0) {
+	if (prog_fd < 0)
 		pr_warn("BPF log buffer:\n%s", log_buf);
-		return prog_fd;
+
+	return prog_fd;
+}
+
+int xsk_attach_xdp_program(int ifindex, int prog_fd, u32 xdp_flags)
+{
+	DECLARE_LIBBPF_OPTS(bpf_link_create_opts, opts);
+	__u32 prog_id = 0;
+	int link_fd;
+	int err;
+
+	err = bpf_xdp_query_id(ifindex, xdp_flags, &prog_id);
+	if (err) {
+		pr_warn("getting XDP prog id failed\n");
+		return err;
 	}
 
-	ctx->prog_fd = prog_fd;
-	return 0;
+	/* If there's a netlink-based XDP prog loaded on interface, bail out
+	 * and ask user to do the removal by himself
+	 */
+	if (prog_id) {
+		pr_warn("Netlink-based XDP prog detected, please unload it in order to launch AF_XDP prog\n");
+		return -EINVAL;
+	}
+
+	opts.flags = xdp_flags & ~(XDP_FLAGS_UPDATE_IF_NOEXIST | XDP_FLAGS_REPLACE);
+
+	link_fd = bpf_link_create(prog_fd, ifindex, BPF_XDP, &opts);
+	if (link_fd < 0)
+		pr_warn("bpf_link_create failed: %s\n", strerror(errno));
+
+	return link_fd;
 }
 
 static int xsk_create_bpf_link(struct xsk_socket *xsk)
@@ -775,7 +803,7 @@ static int xsk_init_xdp_res(struct xsk_socket *xsk,
 	if (err)
 		return err;
 
-	err = xsk_load_xdp_prog(xsk);
+	err = __xsk_load_xdp_prog(*xsks_map_fd);
 	if (err)
 		goto err_load_xdp_prog;
 
@@ -871,6 +899,22 @@ int xsk_setup_xdp_prog_xsk(struct xsk_socket *xsk, int *xsks_map_fd)
 	return __xsk_setup_xdp_prog(xsk, xsks_map_fd);
 }
 
+int xsk_load_xdp_program(int *xsk_map_fd, int *prog_fd)
+{
+	*xsk_map_fd = bpf_map_create(BPF_MAP_TYPE_XSKMAP, "xsks_map", sizeof(int), sizeof(int),
+				     XSKMAP_SIZE, NULL);
+	if (*xsk_map_fd < 0)
+		return *xsk_map_fd;
+
+	*prog_fd = __xsk_load_xdp_prog(*xsk_map_fd);
+	if (*prog_fd < 0) {
+		close(*xsk_map_fd);
+		return *prog_fd;
+	}
+
+	return 0;
+}
+
 static struct xsk_ctx *xsk_get_ctx(struct xsk_umem *umem, int ifindex,
 				   __u32 queue_id)
 {
@@ -917,7 +961,7 @@ out_free:
 
 static struct xsk_ctx *xsk_create_ctx(struct xsk_socket *xsk,
 				      struct xsk_umem *umem, int ifindex,
-				      const char *ifname, __u32 queue_id,
+				      __u32 queue_id,
 				      struct xsk_ring_prod *fill,
 				      struct xsk_ring_cons *comp)
 {
@@ -944,7 +988,6 @@ static struct xsk_ctx *xsk_create_ctx(struct xsk_socket *xsk,
 	ctx->refcount = 1;
 	ctx->umem = umem;
 	ctx->queue_id = queue_id;
-	bpf_strlcpy(ctx->ifname, ifname, IFNAMSIZ);
 	ctx->prog_fd = FD_NOT_USED;
 	ctx->link_fd = FD_NOT_USED;
 	ctx->xsks_map_fd = FD_NOT_USED;
@@ -991,7 +1034,7 @@ int xsk_setup_xdp_prog(int ifindex, int *xsks_map_fd)
 }
 
 int xsk_socket__create_shared(struct xsk_socket **xsk_ptr,
-			      const char *ifname,
+			      int ifindex,
 			      __u32 queue_id, struct xsk_umem *umem,
 			      struct xsk_ring_cons *rx,
 			      struct xsk_ring_prod *tx,
@@ -1005,7 +1048,7 @@ int xsk_socket__create_shared(struct xsk_socket **xsk_ptr,
 	struct xdp_mmap_offsets off;
 	struct xsk_socket *xsk;
 	struct xsk_ctx *ctx;
-	int err, ifindex;
+	int err;
 
 	if (!umem || !xsk_ptr || !(rx || tx))
 		return -EFAULT;
@@ -1020,12 +1063,6 @@ int xsk_socket__create_shared(struct xsk_socket **xsk_ptr,
 	if (err)
 		goto out_xsk_alloc;
 
-	ifindex = if_nametoindex(ifname);
-	if (!ifindex) {
-		err = -errno;
-		goto out_xsk_alloc;
-	}
-
 	if (umem->refcount++ > 0) {
 		xsk->fd = socket(AF_XDP, SOCK_RAW | SOCK_CLOEXEC, 0);
 		if (xsk->fd < 0) {
@@ -1045,8 +1082,7 @@ int xsk_socket__create_shared(struct xsk_socket **xsk_ptr,
 			goto out_socket;
 		}
 
-		ctx = xsk_create_ctx(xsk, umem, ifindex, ifname, queue_id,
-				     fill, comp);
+		ctx = xsk_create_ctx(xsk, umem, ifindex, queue_id, fill, comp);
 		if (!ctx) {
 			err = -ENOMEM;
 			goto out_socket;
@@ -1144,12 +1180,6 @@ int xsk_socket__create_shared(struct xsk_socket **xsk_ptr,
 		goto out_mmap_tx;
 	}
 
-	if (!(xsk->config.libbpf_flags & XSK_LIBBPF_FLAGS__INHIBIT_PROG_LOAD)) {
-		err = __xsk_setup_xdp_prog(xsk, NULL);
-		if (err)
-			goto out_mmap_tx;
-	}
-
 	*xsk_ptr = xsk;
 	umem->fill_save = NULL;
 	umem->comp_save = NULL;
@@ -1173,7 +1203,7 @@ out_xsk_alloc:
 	return err;
 }
 
-int xsk_socket__create(struct xsk_socket **xsk_ptr, const char *ifname,
+int xsk_socket__create(struct xsk_socket **xsk_ptr, int ifindex,
 		       __u32 queue_id, struct xsk_umem *umem,
 		       struct xsk_ring_cons *rx, struct xsk_ring_prod *tx,
 		       const struct xsk_socket_config *usr_config)
@@ -1181,7 +1211,7 @@ int xsk_socket__create(struct xsk_socket **xsk_ptr, const char *ifname,
 	if (!umem)
 		return -EFAULT;
 
-	return xsk_socket__create_shared(xsk_ptr, ifname, queue_id, umem,
+	return xsk_socket__create_shared(xsk_ptr, ifindex, queue_id, umem,
 					 rx, tx, umem->fill_save,
 					 umem->comp_save, usr_config);
 }