xdp-loader: introduce features command

Add features command to xdp-loader in order to dump XDP features
supported by the NIC.

Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>

configure

@@ -284,6 +284,7 @@ check_libbpf_functions()
     check_libbpf_function "bpf_xdp_attach" "(0, 0, 0, NULL)" "" "$LIBBPF_CFLAGS" "$LIBBPF_LDLIBS"
     check_libbpf_function "bpf_map__set_autocreate" "(NULL, false)" "" "$LIBBPF_CFLAGS" "$LIBBPF_LDLIBS"
     check_libbpf_function "bpf_prog_test_run_opts" "(0, &opts)" "DECLARE_LIBBPF_OPTS(bpf_test_run_opts, opts, .batch_size = 1)" "$LIBBPF_CFLAGS" "$LIBBPF_LDLIBS"
+    check_libbpf_function "bpf_xdp_query" "(0, 0, &opts)" "DECLARE_LIBBPF_OPTS(bpf_xdp_query_opts, opts, .feature_flags = 1)" "$LIBBPF_CFLAGS" "$LIBBPF_LDLIBS"
 }
 
 get_libbpf_version()

headers/linux/netdev.h

@@ -0,0 +1,61 @@
+/* SPDX-License-Identifier: ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) */
+/* Do not edit directly, auto-generated from: */
+/*	Documentation/netlink/specs/netdev.yaml */
+/* YNL-GEN uapi header */
+
+#ifndef _UAPI_LINUX_NETDEV_H
+#define _UAPI_LINUX_NETDEV_H
+
+#define NETDEV_FAMILY_NAME	"netdev"
+#define NETDEV_FAMILY_VERSION	1
+
+/**
+ * enum netdev_xdp_act
+ * @NETDEV_XDP_ACT_BASIC: XDP feautues set supported by all drivers
+ *   (XDP_ABORTED, XDP_DROP, XDP_PASS, XDP_TX)
+ * @NETDEV_XDP_ACT_REDIRECT: The netdev supports XDP_REDIRECT
+ * @NETDEV_XDP_ACT_NDO_XMIT: This feature informs if netdev implements
+ *   ndo_xdp_xmit callback.
+ * @NETDEV_XDP_ACT_XSK_ZEROCOPY: This feature informs if netdev supports AF_XDP
+ *   in zero copy mode.
+ * @NETDEV_XDP_ACT_HW_OFFLOAD: This feature informs if netdev supports XDP hw
+ *   offloading.
+ * @NETDEV_XDP_ACT_RX_SG: This feature informs if netdev implements non-linear
+ *   XDP buffer support in the driver napi callback.
+ * @NETDEV_XDP_ACT_NDO_XMIT_SG: This feature informs if netdev implements
+ *   non-linear XDP buffer support in ndo_xdp_xmit callback.
+ */
+enum netdev_xdp_act {
+	NETDEV_XDP_ACT_BASIC = 1,
+	NETDEV_XDP_ACT_REDIRECT = 2,
+	NETDEV_XDP_ACT_NDO_XMIT = 4,
+	NETDEV_XDP_ACT_XSK_ZEROCOPY = 8,
+	NETDEV_XDP_ACT_HW_OFFLOAD = 16,
+	NETDEV_XDP_ACT_RX_SG = 32,
+	NETDEV_XDP_ACT_NDO_XMIT_SG = 64,
+
+	NETDEV_XDP_ACT_MASK = 127,
+};
+
+enum {
+	NETDEV_A_DEV_IFINDEX = 1,
+	NETDEV_A_DEV_PAD,
+	NETDEV_A_DEV_XDP_FEATURES,
+
+	__NETDEV_A_DEV_MAX,
+	NETDEV_A_DEV_MAX = (__NETDEV_A_DEV_MAX - 1)
+};
+
+enum {
+	NETDEV_CMD_DEV_GET = 1,
+	NETDEV_CMD_DEV_ADD_NTF,
+	NETDEV_CMD_DEV_DEL_NTF,
+	NETDEV_CMD_DEV_CHANGE_NTF,
+
+	__NETDEV_CMD_MAX,
+	NETDEV_CMD_MAX = (__NETDEV_CMD_MAX - 1)
+};
+
+#define NETDEV_MCGRP_MGMT	"mgmt"
+
+#endif /* _UAPI_LINUX_NETDEV_H */

xdp-loader/README.org

@@ -25,6 +25,7 @@ Where COMMAND can be one of:
        load        - load an XDP program on an interface
        unload      - unload an XDP program from an interface
        status      - show current XDP program status
+       features    - show XDP features supported by the NIC
        clean       - clean up detached program links in XDP bpffs directory
        help        - show the list of available commands
 #+end_src
@@ -136,6 +137,38 @@ Enable debug logging. Specify twice for even more verbosity.
 ** -h, --help
 Display a summary of the available options
 
+* The FEATURES command
+The =features= command displays the XDP features supported by the NIC.
+
+Currently supported XDP features are:
+
+** NETDEV_XDP_ACT_BASIC
+The networking device has basic support for running XDP programs, and can
+handle the base set of return codes (XDP_ABORTED, XDP_DROP, XDP_PASS, XDP_TX).
+
+** NETDEV_XDP_ACT_REDIRECT
+The network device supports handling the XDP_REDIRECT return code. This means
+packets can be redirected from this device by XDP.
+
+** NETDEV_XDP_ACT_NDO_XMIT
+The networking interfaces implements the ndo_xdp_xmit callback. This means
+packets can be redirected to this device by XDP.
+
+** NETDEV_XDP_ACT_XSK_ZEROCOPY
+The networking device supports AF_XDP in zero copy mode.
+
+** NETDEV_XDP_ACT_HW_OFFLOAD
+The networking device supports XDP hw offloading.
+
+** NETDEV_XDP_ACT_RX_SG
+The networking device supports non-linear XDP frames on the receive side.
+This means XDP can be used with big MTUs on this device (if the XDP program
+is compiled with fragments support)
+
+** NETDEV_XDP_ACT_NDO_XMIT_SG
+The networking device supports non-linear XDP frames on the transmit side. This
+means non-linear frames can be redirected to this device.
+
 * The CLEAN command
 
 The syntax for the =clean= command is:

xdp-loader/tests/test-xdp-loader.sh

@@ -1,5 +1,5 @@
 XDP_LOADER=${XDP_LOADER:-./xdp-loader}
-ALL_TESTS="test_load test_section test_prog_name test_load_multi test_load_incremental test_load_clobber"
+ALL_TESTS="test_load test_section test_prog_name test_load_multi test_load_incremental test_load_clobber test_features"
 
 test_load()
 {
@@ -90,6 +90,32 @@ test_load_clobber()
     check_run $XDP_LOADER unload $NS --all -vv
 }
 
+check_xdp_feature()
+{
+    check_run ip link add dev v0 type veth peer name v1
+
+    $XDP_LOADER features v0 | grep "$1" | grep -q "$2"
+    ret=$?
+
+    ip link del dev v0
+
+    [ $ret -eq 1 ] && exit 1
+}
+
+test_features()
+{
+    skip_if_missing_kernel_symbol xdp_set_features_flag
+
+    check_xdp_feature NETDEV_XDP_ACT_BASIC yes
+    check_xdp_feature NETDEV_XDP_ACT_REDIRECT yes
+    check_xdp_feature NETDEV_XDP_ACT_NDO_XMIT no
+    check_xdp_feature NETDEV_XDP_ACT_XSK_ZEROCOPY no
+    check_xdp_feature NETDEV_XDP_ACT_HW_OFFLOAD no
+    check_xdp_feature NETDEV_XDP_ACT_RX_SG yes
+    check_xdp_feature NETDEV_XDP_ACT_NDO_XMIT_SG no
+
+    return 0
+}
 
 cleanup_tests()
 {

xdp-loader/xdp-loader.8

@@ -1,4 +1,4 @@
-.TH "xdp-loader" "8" "JANUARY  9, 2023" "V1.3.1" "XDP program loader" 
+.TH "xdp-loader" "8" "JUNE  7, 2023" "V1.3.1" "XDP program loader"
 
 .SH "NAME"
 xdp-loader \- an XDP program loader
@@ -21,6 +21,7 @@ Where COMMAND can be one of:
        load        - load an XDP program on an interface
        unload      - unload an XDP program from an interface
        status      - show current XDP program status
+       features    - show XDP features supported by the NIC
        clean       - clean up detached program links in XDP bpffs directory
        help        - show the list of available commands
 \fP
@@ -160,6 +161,47 @@ Enable debug logging. Specify twice for even more verbosity.
 .PP
 Display a summary of the available options
 
+.SH "The FEATURES command"
+.PP
+The \fIfeatures\fP command displays the XDP features supported by the NIC.
+
+.PP
+Currently supported XDP features are:
+
+.SS "NETDEV_XDP_ACT_BASIC"
+.PP
+The networking device has basic support for running XDP programs, and can
+handle the base set of return codes (XDP_ABORTED, XDP_DROP, XDP_PASS, XDP_TX).
+
+.SS "NETDEV_XDP_ACT_REDIRECT"
+.PP
+The network device supports handling the XDP_REDIRECT return code. This means
+packets can be redirected from this device by XDP.
+
+.SS "NETDEV_XDP_ACT_NDO_XMIT"
+.PP
+The networking interfaces implements the ndo_xdp_xmit callback. This means
+packets can be redirected to this device by XDP.
+
+.SS "NETDEV_XDP_ACT_XSK_ZEROCOPY"
+.PP
+The networking device supports AF_XDP in zero copy mode.
+
+.SS "NETDEV_XDP_ACT_HW_OFFLOAD"
+.PP
+The networking device supports XDP hw offloading.
+
+.SS "NETDEV_XDP_ACT_RX_SG"
+.PP
+The networking device supports non-linear XDP frames on the receive side.
+This means XDP can be used with big MTUs on this device (if the XDP program
+is compiled with fragments support)
+
+.SS "NETDEV_XDP_ACT_NDO_XMIT_SG"
+.PP
+The networking device supports non-linear XDP frames on the transmit side. This
+means non-linear frames can be redirected to this device.
+
 .SH "The CLEAN command"
 .PP
 The syntax for the \fIclean\fP command is:

xdp-loader/xdp-loader.c

@@ -12,6 +12,7 @@
 #include <bpf/libbpf.h>
 #include <xdp/libxdp.h>
 #include <linux/err.h>
+#include <linux/netdev.h>
 
 #include "params.h"
 #include "logging.h"
@@ -377,6 +378,70 @@ int do_clean(const void *cfg, __unused const char *pin_root_path)
 	return libxdp_clean_references(opt->iface.ifindex);
 }
 
+static const struct featuresopt {
+	struct iface iface;
+} defaults_features = {};
+
+static struct prog_option features_options[] = {
+	DEFINE_OPTION("dev", OPT_IFNAME, struct featuresopt, iface,
+		      .positional = true,
+		      .metavar = "<ifname>",
+		      .required = true,
+		      .help = "Show XDP features for device <ifname>"),
+	END_OPTIONS
+};
+
+#define CHECK_XDP_FEATURE(f)	(opts.feature_flags & (f) ? "yes" : "no")
+static int iface_print_xdp_features(const struct iface *iface)
+{
+#ifdef HAVE_LIBBPF_BPF_XDP_QUERY
+	LIBBPF_OPTS(bpf_xdp_query_opts, opts);
+	int err;
+
+	err = bpf_xdp_query(iface->ifindex, 0, &opts);
+	if (err) {
+		pr_warn("The running kernel doesn't support querying XDP features (%d).\n", err);
+		return err;
+	}
+
+	/* NETDEV_XDP features are defined in <linux/netdev.h> kernel header */
+	printf("NETDEV_XDP_ACT_BASIC:\t\t%s\n",
+	       CHECK_XDP_FEATURE(NETDEV_XDP_ACT_BASIC));
+	printf("NETDEV_XDP_ACT_REDIRECT:\t%s\n",
+	       CHECK_XDP_FEATURE(NETDEV_XDP_ACT_REDIRECT));
+	printf("NETDEV_XDP_ACT_NDO_XMIT:\t%s\n",
+	       CHECK_XDP_FEATURE(NETDEV_XDP_ACT_NDO_XMIT));
+	printf("NETDEV_XDP_ACT_XSK_ZEROCOPY:\t%s\n",
+	       CHECK_XDP_FEATURE(NETDEV_XDP_ACT_XSK_ZEROCOPY));
+	printf("NETDEV_XDP_ACT_HW_OFFLOAD:\t%s\n",
+	       CHECK_XDP_FEATURE(NETDEV_XDP_ACT_HW_OFFLOAD));
+	printf("NETDEV_XDP_ACT_RX_SG:\t\t%s\n",
+	       CHECK_XDP_FEATURE(NETDEV_XDP_ACT_RX_SG));
+	printf("NETDEV_XDP_ACT_NDO_XMIT_SG:\t%s\n",
+	       CHECK_XDP_FEATURE(NETDEV_XDP_ACT_NDO_XMIT_SG));
+
+	if (opts.feature_flags & ~NETDEV_XDP_ACT_MASK)
+		pr_debug("unknown reported xdp features: 0x%llx\n",
+			 opts.feature_flags & ~NETDEV_XDP_ACT_MASK);
+
+	return 0;
+#else
+	__unused const void *i = iface;
+
+	pr_warn("Cannot display features, because xdp-loader was compiled against an "
+		"old version of libbpf without support for querying features.\n");
+
+	return -EOPNOTSUPP;
+#endif
+}
+
+int do_features(const void *cfg, __unused const char *pin_root_path)
+{
+	const struct featuresopt *opt = cfg;
+
+	return iface_print_xdp_features(&opt->iface);
+}
+
 int do_help(__unused const void *cfg, __unused const char *pin_root_path)
 {
 	fprintf(stderr,
@@ -387,6 +452,7 @@ int do_help(__unused const void *cfg, __unused const char *pin_root_path)
 		"       unload      - unload an XDP program from an interface\n"
 		"       status      - show current XDP program status\n"
 		"       clean       - clean up detached program links in XDP bpffs directory\n"
+		"       features    - show XDP features supported by the NIC\n"
 		"       help        - show this help message\n"
 		"\n"
 		"Use 'xdp-loader COMMAND --help' to see options for each command\n");
@@ -398,6 +464,7 @@ static const struct prog_command cmds[] = {
 	DEFINE_COMMAND(unload, "Unload an XDP program from an interface"),
 	DEFINE_COMMAND(clean, "Clean up detached program links in XDP bpffs directory"),
 	DEFINE_COMMAND(status, "Show XDP program status"),
+	DEFINE_COMMAND(features, "Show NIC XDP features"),
 	{ .name = "help", .func = do_help, .no_cfg = true },
 	END_COMMANDS
 };
@@ -406,6 +473,7 @@ union all_opts {
 	struct loadopt load;
 	struct unloadopt unload;
 	struct statusopt status;
+	struct featuresopt features;
 };
 
 int main(int argc, char **argv)