@@ -20,6 +20,7 @@
#include <linux/set_memory.h>
#include <linux/kallsyms.h>
+#include <net/xdp.h>
#include <net/sch_generic.h>
#include <uapi/linux/filter.h>
@@ -503,6 +504,7 @@ struct xdp_buff {
void *data_end;
void *data_meta;
void *data_hard_start;
+ struct xdp_rxq_info *rxq;
};
/* Compute the linear packet data range [data, data_end) which
new file mode 100644
@@ -0,0 +1,47 @@
+/* include/net/xdp.h
+ *
+ * Copyright (c) 2017 Jesper Dangaard Brouer, Red Hat Inc.
+ * Released under terms in GPL version 2. See COPYING.
+ */
+#ifndef __LINUX_NET_XDP_H__
+#define __LINUX_NET_XDP_H__
+
+/**
+ * DOC: XDP RX-queue information
+ *
+ * The XDP RX-queue info (xdp_rxq_info) is associated with the driver
+ * level RX-ring queues. It is information that is specific to how
+ * the driver have configured a given RX-ring queue.
+ *
+ * Each xdp_buff frame received in the driver carry a (pointer)
+ * reference to this xdp_rxq_info structure. This provides the XDP
+ * data-path read-access to RX-info for both kernel and bpf-side
+ * (limited subset).
+ *
+ * For now, direct access is only safe while running in NAPI/softirq
+ * context. Contents is read-mostly and must not be updated during
+ * driver NAPI/softirq poll.
+ *
+ * The driver usage API is a register and unregister API.
+ *
+ * The struct is not directly tied to the XDP prog. A new XDP prog
+ * can be attached as long as it doesn't change the underlying
+ * RX-ring. If the RX-ring does change significantly, the NIC driver
+ * naturally need to stop the RX-ring before purging and reallocating
+ * memory. In that process the driver MUST call unregistor (which
+ * also apply for driver shutdown and unload). The register API is
+ * also mandatory during RX-ring setup.
+ */
+
+struct xdp_rxq_info {
+ struct net_device *dev;
+ u32 queue_index;
+ u32 reg_state;
+} ____cacheline_aligned; /* perf critical, avoid false-sharing */
+
+int xdp_rxq_info_reg(struct xdp_rxq_info *xdp_rxq,
+ struct net_device *dev, u32 queue_index);
+void xdp_rxq_info_unreg(struct xdp_rxq_info *xdp_rxq);
+void xdp_rxq_info_unused(struct xdp_rxq_info *xdp_rxq);
+
+#endif /* __LINUX_NET_XDP_H__ */
@@ -11,7 +11,7 @@ obj-$(CONFIG_SYSCTL) += sysctl_net_core.o
obj-y += dev.o ethtool.o dev_addr_lists.o dst.o netevent.o \
neighbour.o rtnetlink.o utils.o link_watch.o filter.o \
sock_diag.o dev_ioctl.o tso.o sock_reuseport.o \
- fib_notifier.o
+ fib_notifier.o xdp.o
obj-y += net-sysfs.o
obj-$(CONFIG_PROC_FS) += net-procfs.o
new file mode 100644
@@ -0,0 +1,67 @@
+/* net/core/xdp.c
+ *
+ * Copyright (c) 2017 Jesper Dangaard Brouer, Red Hat Inc.
+ * Released under terms in GPL version 2. See COPYING.
+ */
+#include <linux/types.h>
+#include <linux/mm.h>
+
+#include <net/xdp.h>
+
+#define REG_STATE_NEW 0x0
+#define REG_STATE_REGISTERED 0x1
+#define REG_STATE_UNREGISTERED 0x2
+#define REG_STATE_UNUSED 0x3
+
+void xdp_rxq_info_unreg(struct xdp_rxq_info *xdp_rxq)
+{
+ /* Simplify driver cleanup code paths, allow unreg "unused" */
+ if (xdp_rxq->reg_state == REG_STATE_UNUSED)
+ return;
+
+ WARN(!(xdp_rxq->reg_state == REG_STATE_REGISTERED), "Driver BUG");
+
+ xdp_rxq->reg_state = REG_STATE_UNREGISTERED;
+ xdp_rxq->dev = NULL;
+}
+EXPORT_SYMBOL_GPL(xdp_rxq_info_unreg);
+
+static void xdp_rxq_info_init(struct xdp_rxq_info *xdp_rxq)
+{
+ memset(xdp_rxq, 0, sizeof(*xdp_rxq));
+}
+
+/* Returns 0 on success, negative on failure */
+int xdp_rxq_info_reg(struct xdp_rxq_info *xdp_rxq,
+ struct net_device *dev, u32 queue_index)
+{
+ if (xdp_rxq->reg_state == REG_STATE_UNUSED) {
+ WARN(1, "Driver promised not to register this");
+ return -EINVAL;
+ }
+
+ if (xdp_rxq->reg_state == REG_STATE_REGISTERED) {
+ WARN(1, "Missing unregister, handled but fix driver");
+ xdp_rxq_info_unreg(xdp_rxq);
+ }
+
+ if (!dev) {
+ WARN(1, "Missing net_device from driver");
+ return -ENODEV;
+ }
+
+ /* State either UNREGISTERED or NEW */
+ xdp_rxq_info_init(xdp_rxq);
+ xdp_rxq->dev = dev;
+ xdp_rxq->queue_index = queue_index;
+
+ xdp_rxq->reg_state = REG_STATE_REGISTERED;
+ return 0;
+}
+EXPORT_SYMBOL_GPL(xdp_rxq_info_reg);
+
+void xdp_rxq_info_unused(struct xdp_rxq_info *xdp_rxq)
+{
+ xdp_rxq->reg_state = REG_STATE_UNUSED;
+}
+EXPORT_SYMBOL_GPL(xdp_rxq_info_unused);
This patch only introduce the core data structures and API functions. All XDP enabled drivers must use the API before this info can used. There is a need for XDP to know more about the RX-queue a given XDP frames have arrived on. For both the XDP bpf-prog and kernel side. Instead of extending xdp_buff each time new info is needed, the patch creates a separate read-mostly struct xdp_rxq_info, that contains this info. We stress this data/cache-line is for read-only info. This is NOT for dynamic per packet info, use the data_meta for such use-cases. The performance advantage is this info can be setup at RX-ring init time, instead of updating N-members in xdp_buff. A possible (driver level) micro optimization is that xdp_buff->rxq assignment could be done once per XDP/NAPI loop. The extra pointer deref only happens for program needing access to this info (thus, no slowdown to existing use-cases). Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com> --- include/linux/filter.h | 2 + include/net/xdp.h | 47 ++++++++++++++++++++++++++++++++++ net/core/Makefile | 2 + net/core/xdp.c | 67 ++++++++++++++++++++++++++++++++++++++++++++++++ 4 files changed, 117 insertions(+), 1 deletion(-) create mode 100644 include/net/xdp.h create mode 100644 net/core/xdp.c