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-rw-r--r--src/libknot/xdp/xdp.c585
1 files changed, 585 insertions, 0 deletions
diff --git a/src/libknot/xdp/xdp.c b/src/libknot/xdp/xdp.c
new file mode 100644
index 0000000..8286884
--- /dev/null
+++ b/src/libknot/xdp/xdp.c
@@ -0,0 +1,585 @@
+/* Copyright (C) 2023 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+
+ This program is free software: you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation, either version 3 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program. If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <assert.h>
+#include <errno.h>
+#include <netinet/in.h>
+#include <linux/if_ether.h>
+#include <linux/udp.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+#include <unistd.h>
+
+#include "libknot/attribute.h"
+#include "libknot/endian.h"
+#include "libknot/errcode.h"
+#include "libknot/xdp/bpf-consts.h"
+#include "libknot/xdp/bpf-user.h"
+#include "libknot/xdp/eth.h"
+#include "libknot/xdp/msg_init.h"
+#include "libknot/xdp/protocols.h"
+#include "libknot/xdp/xdp.h"
+#include "contrib/macros.h"
+#include "contrib/net.h"
+
+#define FRAME_SIZE 2048
+
+#define FRAME_COUNT_TX 2048
+#define FRAME_COUNT_RX 2048
+#define FRAME_COUNT (FRAME_COUNT_TX + FRAME_COUNT_RX)
+
+#define RING_LEN_TX FRAME_COUNT_TX
+#define RING_LEN_CQ FRAME_COUNT_TX
+#define RING_LEN_RX FRAME_COUNT_RX
+/* It's recommended that the FQ ring size >= HW RX ring size + AF_XDP RX ring size. */
+#define RING_LEN_FQ (2 * FRAME_COUNT_RX)
+
+#define ALLOC_RETRY_NUM 15
+#define ALLOC_RETRY_DELAY 20 // In nanoseconds.
+
+/* With recent compilers we statically check #defines for settings that
+ * get refused by AF_XDP drivers (in current versions, at least). */
+#if (__STDC_VERSION__ >= 201112L)
+#define IS_POWER_OF_2(n) (((n) & (n - 1)) == 0)
+_Static_assert((FRAME_SIZE == 4096 || FRAME_SIZE == 2048)
+ && IS_POWER_OF_2(RING_LEN_TX) && IS_POWER_OF_2(RING_LEN_RX)
+ && IS_POWER_OF_2(RING_LEN_CQ) && IS_POWER_OF_2(RING_LEN_FQ)
+ && FRAME_COUNT_TX <= (1 << 16) /* see tx_free_indices */
+ , "Incorrect #define combination for AF_XDP.");
+#endif
+
+struct umem_frame {
+ uint8_t bytes[FRAME_SIZE];
+};
+
+static int configure_xsk_umem(struct kxsk_umem **out_umem, bool extra_frames)
+{
+ /* Allocate memory and call driver to create the UMEM. */
+ struct kxsk_umem *umem = calloc(1,
+ offsetof(struct kxsk_umem, tx_free_indices)
+ + sizeof(umem->tx_free_indices[0]) * FRAME_COUNT_TX);
+ if (umem == NULL) {
+ return KNOT_ENOMEM;
+ }
+
+ size_t frame_count = FRAME_COUNT + (extra_frames ? FRAME_COUNT_RX : 0);
+
+ int ret = posix_memalign((void **)&umem->frames, getpagesize(),
+ FRAME_SIZE * frame_count);
+ if (ret != 0) {
+ free(umem);
+ return KNOT_ENOMEM;
+ }
+
+ const struct xsk_umem_config config = {
+ .fill_size = RING_LEN_FQ,
+ .comp_size = RING_LEN_CQ,
+ .frame_size = FRAME_SIZE,
+ .frame_headroom = KNOT_XDP_PKT_ALIGNMENT,
+ };
+
+ ret = xsk_umem__create(&umem->umem, umem->frames, FRAME_SIZE * frame_count,
+ &umem->fq, &umem->cq, &config);
+ if (ret != KNOT_EOK) {
+ free(umem->frames);
+ free(umem);
+ return ret;
+ }
+ *out_umem = umem;
+
+ /* Designate the starting chunk of buffers for TX, and put them onto the stack. */
+ umem->tx_free_count = FRAME_COUNT_TX;
+ for (uint32_t i = 0; i < FRAME_COUNT_TX; ++i) {
+ umem->tx_free_indices[i] = i;
+ }
+
+ /* Designate the rest of buffers for RX, and pass them to the driver. */
+ uint32_t idx = 0;
+ ret = xsk_ring_prod__reserve(&umem->fq, frame_count - FRAME_COUNT_TX, &idx);
+ if (ret != frame_count - FRAME_COUNT_TX) {
+ assert(0);
+ return KNOT_ERROR;
+ }
+ assert(idx == 0);
+ for (uint32_t i = FRAME_COUNT_TX; i < frame_count; ++i) {
+ *xsk_ring_prod__fill_addr(&umem->fq, idx++) = i * FRAME_SIZE;
+ }
+ xsk_ring_prod__submit(&umem->fq, frame_count - FRAME_COUNT_TX);
+
+ return KNOT_EOK;
+}
+
+static void deconfigure_xsk_umem(struct kxsk_umem *umem)
+{
+ (void)xsk_umem__delete(umem->umem);
+ free(umem->frames);
+ free(umem);
+}
+
+static int configure_xsk_socket(struct kxsk_umem *umem,
+ const struct kxsk_iface *iface,
+ knot_xdp_socket_t **out_sock,
+ const knot_xdp_config_t *config)
+{
+ knot_xdp_socket_t *xsk_info = calloc(1, sizeof(*xsk_info));
+ if (xsk_info == NULL) {
+ return KNOT_ENOMEM;
+ }
+ xsk_info->iface = iface;
+ xsk_info->umem = umem;
+
+ uint16_t bind_flags = 0;
+ if (config != NULL && config->force_copy) {
+ bind_flags |= XDP_COPY;
+ }
+
+ const struct xsk_socket_config sock_conf = {
+ .tx_size = RING_LEN_TX,
+ .rx_size = RING_LEN_RX,
+ .libbpf_flags = XSK_LIBBPF_FLAGS__INHIBIT_PROG_LOAD,
+ .bind_flags = bind_flags,
+ };
+
+ int ret = xsk_socket__create(&xsk_info->xsk, iface->if_name,
+ iface->if_queue, umem->umem,
+ &xsk_info->rx, &xsk_info->tx, &sock_conf);
+ if (ret != 0) {
+ free(xsk_info);
+ return ret;
+ }
+
+ *out_sock = xsk_info;
+ return KNOT_EOK;
+}
+
+_public_
+int knot_xdp_init(knot_xdp_socket_t **socket, const char *if_name, int if_queue,
+ knot_xdp_filter_flag_t flags, uint16_t udp_port, uint16_t quic_port,
+ knot_xdp_load_bpf_t load_bpf, const knot_xdp_config_t *xdp_config)
+{
+ if (socket == NULL || if_name == NULL ||
+ (udp_port == quic_port && (flags & KNOT_XDP_FILTER_UDP) && (flags & KNOT_XDP_FILTER_QUIC)) ||
+ (flags & (KNOT_XDP_FILTER_UDP | KNOT_XDP_FILTER_TCP | KNOT_XDP_FILTER_QUIC)) == 0) {
+ return KNOT_EINVAL;
+ }
+
+ struct kxsk_iface *iface;
+ const bool generic_xdp = (xdp_config != NULL && xdp_config->force_generic);
+ int ret = kxsk_iface_new(if_name, if_queue, load_bpf, generic_xdp, &iface);
+ if (ret != KNOT_EOK) {
+ return ret;
+ }
+
+ /* Initialize shared packet_buffer for umem usage. */
+ struct kxsk_umem *umem = NULL;
+ ret = configure_xsk_umem(&umem, xdp_config->extra_frames);
+ if (ret != KNOT_EOK) {
+ kxsk_iface_free(iface);
+ return ret;
+ }
+
+ ret = configure_xsk_socket(umem, iface, socket, xdp_config);
+ if (ret != KNOT_EOK) {
+ deconfigure_xsk_umem(umem);
+ kxsk_iface_free(iface);
+ return ret;
+ }
+
+ (*socket)->frame_limit = FRAME_SIZE;
+ ret = knot_eth_mtu(if_name);
+ if (ret > 0) {
+ (*socket)->frame_limit = MIN((unsigned)ret, (*socket)->frame_limit);
+ }
+
+ if (flags & KNOT_XDP_FILTER_ROUTE) {
+ ret = knot_eth_vlans(&(*socket)->vlan_map, &(*socket)->vlan_map_max);
+ if (ret != KNOT_EOK) {
+ xsk_socket__delete((*socket)->xsk);
+ deconfigure_xsk_umem(umem);
+ kxsk_iface_free(iface);
+ free(*socket);
+ *socket = NULL;
+ return ret;
+ }
+ }
+
+ ret = kxsk_socket_start(iface, flags, udp_port, quic_port, (*socket)->xsk);
+ if (ret != KNOT_EOK) {
+ free((*socket)->vlan_map);
+ xsk_socket__delete((*socket)->xsk);
+ deconfigure_xsk_umem(umem);
+ kxsk_iface_free(iface);
+ free(*socket);
+ *socket = NULL;
+ return ret;
+ }
+
+ return ret;
+}
+
+_public_
+void knot_xdp_deinit(knot_xdp_socket_t *socket)
+{
+ if (socket == NULL) {
+ return;
+ }
+ if (unlikely(socket->send_mock != NULL)) {
+ free(socket);
+ return;
+ }
+
+ kxsk_socket_stop(socket->iface);
+ xsk_socket__delete(socket->xsk);
+ deconfigure_xsk_umem(socket->umem);
+
+ kxsk_iface_free((struct kxsk_iface *)/*const-cast*/socket->iface);
+ free(socket->vlan_map);
+ free(socket);
+}
+
+_public_
+int knot_xdp_socket_fd(knot_xdp_socket_t *socket)
+{
+ if (socket == NULL) {
+ return 0;
+ }
+
+ return xsk_socket__fd(socket->xsk);
+}
+
+static void tx_free_relative(struct kxsk_umem *umem, uint64_t addr_relative)
+{
+ /* The address may not point to *start* of buffer, but `/` solves that. */
+ uint64_t index = addr_relative / FRAME_SIZE;
+ assert(index < FRAME_COUNT);
+ umem->tx_free_indices[umem->tx_free_count++] = index;
+}
+
+_public_
+void knot_xdp_send_prepare(knot_xdp_socket_t *socket)
+{
+ if (socket == NULL || unlikely(socket->send_mock != NULL)) {
+ return;
+ }
+
+ struct kxsk_umem *const umem = socket->umem;
+ struct xsk_ring_cons *const cq = &umem->cq;
+
+ uint32_t idx = 0;
+ const uint32_t completed = xsk_ring_cons__peek(cq, UINT32_MAX, &idx);
+ if (completed == 0) {
+ return;
+ }
+ assert(umem->tx_free_count + completed <= FRAME_COUNT_TX);
+
+ for (uint32_t i = 0; i < completed; ++i) {
+ uint64_t addr_relative = *xsk_ring_cons__comp_addr(cq, idx++);
+ tx_free_relative(umem, addr_relative);
+ }
+
+ xsk_ring_cons__release(cq, completed);
+}
+
+static struct umem_frame *alloc_tx_frame(knot_xdp_socket_t *socket)
+{
+ if (unlikely(socket->send_mock != NULL)) {
+ return malloc(sizeof(struct umem_frame));
+ }
+
+ const struct timespec delay = { .tv_nsec = ALLOC_RETRY_DELAY };
+ struct kxsk_umem *umem = socket->umem;
+
+ for (int i = 0; unlikely(umem->tx_free_count == 0); i++) {
+ if (i == ALLOC_RETRY_NUM) {
+ return NULL;
+ }
+ nanosleep(&delay, NULL);
+ knot_xdp_send_prepare(socket);
+ }
+
+ uint32_t index = umem->tx_free_indices[--umem->tx_free_count];
+ return umem->frames + index;
+}
+
+static void prepare_payload(knot_xdp_msg_t *msg, void *uframe)
+{
+ size_t hdr_len = prot_write_hdrs_len(msg);
+ msg->payload.iov_base = uframe + hdr_len + KNOT_XDP_PKT_ALIGNMENT;
+ msg->payload.iov_len = FRAME_SIZE - hdr_len - KNOT_XDP_PKT_ALIGNMENT;
+}
+
+_public_
+int knot_xdp_send_alloc(knot_xdp_socket_t *socket, knot_xdp_msg_flag_t flags,
+ knot_xdp_msg_t *out)
+{
+ if (socket == NULL || out == NULL) {
+ return KNOT_EINVAL;
+ }
+
+ struct umem_frame *uframe = alloc_tx_frame(socket);
+ if (uframe == NULL) {
+ return KNOT_ENOMEM;
+ }
+
+ msg_init(out, flags);
+ prepare_payload(out, uframe);
+
+ return KNOT_EOK;
+}
+
+_public_
+int knot_xdp_reply_alloc(knot_xdp_socket_t *socket, const knot_xdp_msg_t *query,
+ knot_xdp_msg_t *out)
+{
+ if (socket == NULL || query == NULL || out == NULL) {
+ return KNOT_EINVAL;
+ }
+
+ struct umem_frame *uframe = alloc_tx_frame(socket);
+ if (uframe == NULL) {
+ return KNOT_ENOMEM;
+ }
+
+ msg_init_reply(out, query);
+ prepare_payload(out, uframe);
+
+ return KNOT_EOK;
+}
+
+static void free_unsent(knot_xdp_socket_t *socket, const knot_xdp_msg_t *msg)
+{
+ if (unlikely(socket->send_mock != NULL)) {
+ free(msg->payload.iov_base - prot_write_hdrs_len(msg) - KNOT_XDP_PKT_ALIGNMENT);
+ return;
+ }
+ uint64_t addr_relative = (uint8_t *)msg->payload.iov_base
+ - socket->umem->frames->bytes;
+ tx_free_relative(socket->umem, addr_relative);
+}
+
+_public_
+int knot_xdp_send(knot_xdp_socket_t *socket, const knot_xdp_msg_t msgs[],
+ uint32_t count, uint32_t *sent)
+{
+ if (socket == NULL || msgs == NULL || sent == NULL) {
+ return KNOT_EINVAL;
+ }
+ if (unlikely(socket->send_mock != NULL)) {
+ int ret = socket->send_mock(socket, msgs, count, sent);
+ for (uint32_t i = 0; i < count; ++i) {
+ free_unsent(socket, &msgs[i]);
+ }
+ return ret;
+ }
+
+ /* Now we want to do something close to
+ * xsk_ring_prod__reserve(&socket->tx, count, *idx)
+ * but we don't know in advance if we utilize *whole* `count`,
+ * and the API doesn't allow "cancelling reservations".
+ * Therefore we handle `socket->tx.cached_prod` by hand.
+ */
+ if (xsk_prod_nb_free(&socket->tx, count) < count) {
+ /* This situation was sometimes observed in the emulated XDP mode. */
+ for (uint32_t i = 0; i < count; ++i) {
+ free_unsent(socket, &msgs[i]);
+ }
+ return KNOT_ENOBUFS;
+ }
+ uint32_t idx = socket->tx.cached_prod;
+
+ for (uint32_t i = 0; i < count; ++i) {
+ const knot_xdp_msg_t *msg = &msgs[i];
+
+ if (empty_msg(msg)) {
+ free_unsent(socket, msg);
+ } else {
+ size_t hdr_len = prot_write_hdrs_len(msg);
+ size_t tot_len = hdr_len + msg->payload.iov_len;
+ uint8_t *msg_beg = msg->payload.iov_base - hdr_len;
+ uint16_t mss = MIN(socket->frame_limit - hdr_len, KNOT_TCP_MSS);
+ prot_write_eth(msg_beg, msg, msg_beg + tot_len, mss);
+
+ *xsk_ring_prod__tx_desc(&socket->tx, idx++) = (struct xdp_desc) {
+ .addr = msg_beg - socket->umem->frames->bytes,
+ .len = tot_len,
+ };
+ }
+ }
+
+ *sent = idx - socket->tx.cached_prod;
+ assert(*sent <= count);
+ socket->tx.cached_prod = idx;
+ xsk_ring_prod__submit(&socket->tx, *sent);
+ socket->kernel_needs_wakeup = true;
+
+ return KNOT_EOK;
+}
+
+_public_
+void knot_xdp_send_free(knot_xdp_socket_t *socket, const knot_xdp_msg_t msgs[],
+ uint32_t count)
+{
+ for (uint32_t i = 0; i < count; i++) {
+ free_unsent(socket, &msgs[i]);
+ }
+}
+
+_public_
+int knot_xdp_send_finish(knot_xdp_socket_t *socket)
+{
+ if (socket == NULL) {
+ return KNOT_EINVAL;
+ }
+
+ /* Trigger sending queued packets. */
+ if (!socket->kernel_needs_wakeup) {
+ return KNOT_EOK;
+ }
+
+ int ret = sendto(xsk_socket__fd(socket->xsk), NULL, 0, MSG_DONTWAIT, NULL, 0);
+ const bool is_ok = (ret >= 0);
+ // List of "safe" errors taken from
+ // https://github.com/torvalds/linux/blame/master/samples/bpf/xdpsock_user.c
+ const bool is_again = !is_ok && (errno == ENOBUFS || errno == EAGAIN
+ || errno == EBUSY || errno == ENETDOWN);
+ // Some of the !is_ok cases are a little unclear - what to do about the syscall,
+ // including how caller of _sendmsg_finish() should react.
+ if (is_ok || !is_again) {
+ socket->kernel_needs_wakeup = false;
+ }
+ if (is_again) {
+ return KNOT_EAGAIN;
+ } else if (is_ok) {
+ return KNOT_EOK;
+ } else {
+ return -errno;
+ }
+ /* This syscall might be avoided with a newer kernel feature (>= 5.4):
+ https://www.kernel.org/doc/html/latest/networking/af_xdp.html#xdp-use-need-wakeup-bind-flag
+ Unfortunately it's not easy to continue supporting older kernels
+ when using this feature on newer ones.
+ */
+}
+
+_public_
+int knot_xdp_recv(knot_xdp_socket_t *socket, knot_xdp_msg_t msgs[],
+ uint32_t max_count, uint32_t *count, size_t *wire_size)
+{
+ if (socket == NULL || msgs == NULL || count == NULL) {
+ return KNOT_EINVAL;
+ }
+
+ uint32_t idx = 0;
+ const uint32_t available = xsk_ring_cons__peek(&socket->rx, max_count, &idx);
+ if (available == 0) {
+ *count = 0;
+ return KNOT_EOK;
+ }
+ assert(available <= max_count);
+
+ for (uint32_t i = 0; i < available; ++i) {
+ knot_xdp_msg_t *msg = &msgs[i];
+ const struct xdp_desc *desc = xsk_ring_cons__rx_desc(&socket->rx, idx++);
+ uint8_t *uframe_p = (uint8_t *)socket->umem->frames + desc->addr;
+
+ void *payl_end;
+ void *payl_start = prot_read_eth(uframe_p, msg, &payl_end,
+ socket->vlan_map, socket->vlan_map_max);
+
+ msg->payload.iov_base = payl_start;
+ msg->payload.iov_len = payl_end - payl_start;
+ msg->mss = MIN(msg->mss, FRAME_SIZE - (payl_start - (void *)uframe_p));
+
+ if (wire_size != NULL) {
+ (*wire_size) += desc->len;
+ }
+ }
+
+ xsk_ring_cons__release(&socket->rx, available);
+ *count = available;
+
+ return KNOT_EOK;
+}
+
+static uint8_t *msg_uframe_ptr(const knot_xdp_msg_t *msg)
+{
+ return NULL + ((msg->payload.iov_base - NULL) & ~(FRAME_SIZE - 1));
+}
+
+_public_
+void knot_xdp_recv_finish(knot_xdp_socket_t *socket, const knot_xdp_msg_t msgs[],
+ uint32_t count)
+{
+ if (socket == NULL || msgs == NULL) {
+ return;
+ }
+
+ const struct timespec delay = { .tv_nsec = ALLOC_RETRY_DELAY };
+
+ struct kxsk_umem *const umem = socket->umem;
+ struct xsk_ring_prod *const fq = &umem->fq;
+
+ uint32_t idx = 0;
+ uint32_t reserved = xsk_ring_prod__reserve(fq, count, &idx);
+ for (int i = 0; unlikely(reserved < count); i++) {
+ if (i == ALLOC_RETRY_NUM) {
+ return;
+ }
+ nanosleep(&delay, NULL);
+ reserved = xsk_ring_prod__reserve(fq, count, &idx);
+ }
+
+ for (uint32_t i = 0; i < reserved; ++i) {
+ uint8_t *uframe_p = msg_uframe_ptr(&msgs[i]);
+ uint64_t offset = uframe_p - umem->frames->bytes;
+ *xsk_ring_prod__fill_addr(fq, idx++) = offset;
+ }
+
+ xsk_ring_prod__submit(fq, reserved);
+}
+
+_public_
+void knot_xdp_socket_info(const knot_xdp_socket_t *socket, FILE *file)
+{
+ if (socket == NULL || file == NULL) {
+ return;
+ }
+
+ // The number of busy frames
+ #define RING_BUSY(ring) \
+ ((*(ring)->producer - *(ring)->consumer) & (ring)->mask)
+
+ #define RING_PRINFO(name, ring) \
+ fprintf(file, "Ring %s: size %4d, busy %4d (prod %4d, cons %4d)\n", \
+ name, (unsigned)(ring)->size, \
+ (unsigned)RING_BUSY((ring)), \
+ (unsigned)*(ring)->producer, (unsigned)*(ring)->consumer)
+
+ const int rx_busyf = RING_BUSY(&socket->umem->fq) + RING_BUSY(&socket->rx);
+ fprintf(file, "\nLOST RX frames: %4d", (int)(FRAME_COUNT_RX - rx_busyf));
+
+ const int tx_busyf = RING_BUSY(&socket->umem->cq) + RING_BUSY(&socket->tx);
+ const int tx_freef = socket->umem->tx_free_count;
+ fprintf(file, "\nLOST TX frames: %4d\n", (int)(FRAME_COUNT_TX - tx_busyf - tx_freef));
+
+ RING_PRINFO("FQ", &socket->umem->fq);
+ RING_PRINFO("RX", &socket->rx);
+ RING_PRINFO("TX", &socket->tx);
+ RING_PRINFO("CQ", &socket->umem->cq);
+ fprintf(file, "TX free frames: %4d\n", tx_freef);
+}
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