blob: 38e600703a3d5478db8e4a8a92c10a2ace174c4c [file] [log] [blame]
/*
* AF_XDP network backend.
*
* Copyright (c) 2023 Red Hat, Inc.
*
* Authors:
* Ilya Maximets <i.maximets@ovn.org>
*
* This work is licensed under the terms of the GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
*/
#include "qemu/osdep.h"
#include <bpf/bpf.h>
#include <linux/if_link.h>
#include <linux/if_xdp.h>
#include <net/if.h>
#include <xdp/xsk.h>
#include "clients.h"
#include "monitor/monitor.h"
#include "net/net.h"
#include "qapi/error.h"
#include "qemu/cutils.h"
#include "qemu/error-report.h"
#include "qemu/iov.h"
#include "qemu/main-loop.h"
#include "qemu/memalign.h"
typedef struct AFXDPState {
NetClientState nc;
struct xsk_socket *xsk;
struct xsk_ring_cons rx;
struct xsk_ring_prod tx;
struct xsk_ring_cons cq;
struct xsk_ring_prod fq;
char ifname[IFNAMSIZ];
int ifindex;
bool read_poll;
bool write_poll;
uint32_t outstanding_tx;
uint64_t *pool;
uint32_t n_pool;
char *buffer;
struct xsk_umem *umem;
uint32_t n_queues;
uint32_t xdp_flags;
bool inhibit;
} AFXDPState;
#define AF_XDP_BATCH_SIZE 64
static void af_xdp_send(void *opaque);
static void af_xdp_writable(void *opaque);
/* Set the event-loop handlers for the af-xdp backend. */
static void af_xdp_update_fd_handler(AFXDPState *s)
{
qemu_set_fd_handler(xsk_socket__fd(s->xsk),
s->read_poll ? af_xdp_send : NULL,
s->write_poll ? af_xdp_writable : NULL,
s);
}
/* Update the read handler. */
static void af_xdp_read_poll(AFXDPState *s, bool enable)
{
if (s->read_poll != enable) {
s->read_poll = enable;
af_xdp_update_fd_handler(s);
}
}
/* Update the write handler. */
static void af_xdp_write_poll(AFXDPState *s, bool enable)
{
if (s->write_poll != enable) {
s->write_poll = enable;
af_xdp_update_fd_handler(s);
}
}
static void af_xdp_poll(NetClientState *nc, bool enable)
{
AFXDPState *s = DO_UPCAST(AFXDPState, nc, nc);
if (s->read_poll != enable || s->write_poll != enable) {
s->write_poll = enable;
s->read_poll = enable;
af_xdp_update_fd_handler(s);
}
}
static void af_xdp_complete_tx(AFXDPState *s)
{
uint32_t idx = 0;
uint32_t done, i;
uint64_t *addr;
done = xsk_ring_cons__peek(&s->cq, XSK_RING_CONS__DEFAULT_NUM_DESCS, &idx);
for (i = 0; i < done; i++) {
addr = (void *) xsk_ring_cons__comp_addr(&s->cq, idx++);
s->pool[s->n_pool++] = *addr;
s->outstanding_tx--;
}
if (done) {
xsk_ring_cons__release(&s->cq, done);
}
}
/*
* The fd_write() callback, invoked if the fd is marked as writable
* after a poll.
*/
static void af_xdp_writable(void *opaque)
{
AFXDPState *s = opaque;
/* Try to recover buffers that are already sent. */
af_xdp_complete_tx(s);
/*
* Unregister the handler, unless we still have packets to transmit
* and kernel needs a wake up.
*/
if (!s->outstanding_tx || !xsk_ring_prod__needs_wakeup(&s->tx)) {
af_xdp_write_poll(s, false);
}
/* Flush any buffered packets. */
qemu_flush_queued_packets(&s->nc);
}
static ssize_t af_xdp_receive(NetClientState *nc,
const uint8_t *buf, size_t size)
{
AFXDPState *s = DO_UPCAST(AFXDPState, nc, nc);
struct xdp_desc *desc;
uint32_t idx;
void *data;
/* Try to recover buffers that are already sent. */
af_xdp_complete_tx(s);
if (size > XSK_UMEM__DEFAULT_FRAME_SIZE) {
/* We can't transmit packet this size... */
return size;
}
if (!s->n_pool || !xsk_ring_prod__reserve(&s->tx, 1, &idx)) {
/*
* Out of buffers or space in tx ring. Poll until we can write.
* This will also kick the Tx, if it was waiting on CQ.
*/
af_xdp_write_poll(s, true);
return 0;
}
desc = xsk_ring_prod__tx_desc(&s->tx, idx);
desc->addr = s->pool[--s->n_pool];
desc->len = size;
data = xsk_umem__get_data(s->buffer, desc->addr);
memcpy(data, buf, size);
xsk_ring_prod__submit(&s->tx, 1);
s->outstanding_tx++;
if (xsk_ring_prod__needs_wakeup(&s->tx)) {
af_xdp_write_poll(s, true);
}
return size;
}
/*
* Complete a previous send (backend --> guest) and enable the
* fd_read callback.
*/
static void af_xdp_send_completed(NetClientState *nc, ssize_t len)
{
AFXDPState *s = DO_UPCAST(AFXDPState, nc, nc);
af_xdp_read_poll(s, true);
}
static void af_xdp_fq_refill(AFXDPState *s, uint32_t n)
{
uint32_t i, idx = 0;
/* Leave one packet for Tx, just in case. */
if (s->n_pool < n + 1) {
n = s->n_pool;
}
if (!n || !xsk_ring_prod__reserve(&s->fq, n, &idx)) {
return;
}
for (i = 0; i < n; i++) {
*xsk_ring_prod__fill_addr(&s->fq, idx++) = s->pool[--s->n_pool];
}
xsk_ring_prod__submit(&s->fq, n);
if (xsk_ring_prod__needs_wakeup(&s->fq)) {
/* Receive was blocked by not having enough buffers. Wake it up. */
af_xdp_read_poll(s, true);
}
}
static void af_xdp_send(void *opaque)
{
uint32_t i, n_rx, idx = 0;
AFXDPState *s = opaque;
n_rx = xsk_ring_cons__peek(&s->rx, AF_XDP_BATCH_SIZE, &idx);
if (!n_rx) {
return;
}
for (i = 0; i < n_rx; i++) {
const struct xdp_desc *desc;
struct iovec iov;
desc = xsk_ring_cons__rx_desc(&s->rx, idx++);
iov.iov_base = xsk_umem__get_data(s->buffer, desc->addr);
iov.iov_len = desc->len;
s->pool[s->n_pool++] = desc->addr;
if (!qemu_sendv_packet_async(&s->nc, &iov, 1,
af_xdp_send_completed)) {
/*
* The peer does not receive anymore. Packet is queued, stop
* reading from the backend until af_xdp_send_completed().
*/
af_xdp_read_poll(s, false);
/* Return unused descriptors to not break the ring cache. */
xsk_ring_cons__cancel(&s->rx, n_rx - i - 1);
n_rx = i + 1;
break;
}
}
/* Release actually sent descriptors and try to re-fill. */
xsk_ring_cons__release(&s->rx, n_rx);
af_xdp_fq_refill(s, AF_XDP_BATCH_SIZE);
}
/* Flush and close. */
static void af_xdp_cleanup(NetClientState *nc)
{
AFXDPState *s = DO_UPCAST(AFXDPState, nc, nc);
qemu_purge_queued_packets(nc);
af_xdp_poll(nc, false);
xsk_socket__delete(s->xsk);
s->xsk = NULL;
g_free(s->pool);
s->pool = NULL;
xsk_umem__delete(s->umem);
s->umem = NULL;
qemu_vfree(s->buffer);
s->buffer = NULL;
/* Remove the program if it's the last open queue. */
if (!s->inhibit && nc->queue_index == s->n_queues - 1 && s->xdp_flags
&& bpf_xdp_detach(s->ifindex, s->xdp_flags, NULL) != 0) {
fprintf(stderr,
"af-xdp: unable to remove XDP program from '%s', ifindex: %d\n",
s->ifname, s->ifindex);
}
}
static int af_xdp_umem_create(AFXDPState *s, int sock_fd, Error **errp)
{
struct xsk_umem_config config = {
.fill_size = XSK_RING_PROD__DEFAULT_NUM_DESCS,
.comp_size = XSK_RING_CONS__DEFAULT_NUM_DESCS,
.frame_size = XSK_UMEM__DEFAULT_FRAME_SIZE,
.frame_headroom = 0,
};
uint64_t n_descs;
uint64_t size;
int64_t i;
int ret;
/* Number of descriptors if all 4 queues (rx, tx, cq, fq) are full. */
n_descs = (XSK_RING_PROD__DEFAULT_NUM_DESCS
+ XSK_RING_CONS__DEFAULT_NUM_DESCS) * 2;
size = n_descs * XSK_UMEM__DEFAULT_FRAME_SIZE;
s->buffer = qemu_memalign(qemu_real_host_page_size(), size);
memset(s->buffer, 0, size);
if (sock_fd < 0) {
ret = xsk_umem__create(&s->umem, s->buffer, size,
&s->fq, &s->cq, &config);
} else {
ret = xsk_umem__create_with_fd(&s->umem, sock_fd, s->buffer, size,
&s->fq, &s->cq, &config);
}
if (ret) {
qemu_vfree(s->buffer);
error_setg_errno(errp, errno,
"failed to create umem for %s queue_index: %d",
s->ifname, s->nc.queue_index);
return -1;
}
s->pool = g_new(uint64_t, n_descs);
/* Fill the pool in the opposite order, because it's a LIFO queue. */
for (i = n_descs; i >= 0; i--) {
s->pool[i] = i * XSK_UMEM__DEFAULT_FRAME_SIZE;
}
s->n_pool = n_descs;
af_xdp_fq_refill(s, XSK_RING_PROD__DEFAULT_NUM_DESCS);
return 0;
}
static int af_xdp_socket_create(AFXDPState *s,
const NetdevAFXDPOptions *opts, Error **errp)
{
struct xsk_socket_config cfg = {
.rx_size = XSK_RING_CONS__DEFAULT_NUM_DESCS,
.tx_size = XSK_RING_PROD__DEFAULT_NUM_DESCS,
.libxdp_flags = 0,
.bind_flags = XDP_USE_NEED_WAKEUP,
.xdp_flags = XDP_FLAGS_UPDATE_IF_NOEXIST,
};
int queue_id, error = 0;
s->inhibit = opts->has_inhibit && opts->inhibit;
if (s->inhibit) {
cfg.libxdp_flags |= XSK_LIBXDP_FLAGS__INHIBIT_PROG_LOAD;
}
if (opts->has_force_copy && opts->force_copy) {
cfg.bind_flags |= XDP_COPY;
}
queue_id = s->nc.queue_index;
if (opts->has_start_queue && opts->start_queue > 0) {
queue_id += opts->start_queue;
}
if (opts->has_mode) {
/* Specific mode requested. */
cfg.xdp_flags |= (opts->mode == AFXDP_MODE_NATIVE)
? XDP_FLAGS_DRV_MODE : XDP_FLAGS_SKB_MODE;
if (xsk_socket__create(&s->xsk, s->ifname, queue_id,
s->umem, &s->rx, &s->tx, &cfg)) {
error = errno;
}
} else {
/* No mode requested, try native first. */
cfg.xdp_flags |= XDP_FLAGS_DRV_MODE;
if (xsk_socket__create(&s->xsk, s->ifname, queue_id,
s->umem, &s->rx, &s->tx, &cfg)) {
/* Can't use native mode, try skb. */
cfg.xdp_flags &= ~XDP_FLAGS_DRV_MODE;
cfg.xdp_flags |= XDP_FLAGS_SKB_MODE;
if (xsk_socket__create(&s->xsk, s->ifname, queue_id,
s->umem, &s->rx, &s->tx, &cfg)) {
error = errno;
}
}
}
if (error) {
error_setg_errno(errp, error,
"failed to create AF_XDP socket for %s queue_id: %d",
s->ifname, queue_id);
return -1;
}
s->xdp_flags = cfg.xdp_flags;
return 0;
}
/* NetClientInfo methods. */
static NetClientInfo net_af_xdp_info = {
.type = NET_CLIENT_DRIVER_AF_XDP,
.size = sizeof(AFXDPState),
.receive = af_xdp_receive,
.poll = af_xdp_poll,
.cleanup = af_xdp_cleanup,
};
static int *parse_socket_fds(const char *sock_fds_str,
int64_t n_expected, Error **errp)
{
gchar **substrings = g_strsplit(sock_fds_str, ":", -1);
int64_t i, n_sock_fds = g_strv_length(substrings);
int *sock_fds = NULL;
if (n_sock_fds != n_expected) {
error_setg(errp, "expected %"PRIi64" socket fds, got %"PRIi64,
n_expected, n_sock_fds);
goto exit;
}
sock_fds = g_new(int, n_sock_fds);
for (i = 0; i < n_sock_fds; i++) {
sock_fds[i] = monitor_fd_param(monitor_cur(), substrings[i], errp);
if (sock_fds[i] < 0) {
g_free(sock_fds);
sock_fds = NULL;
goto exit;
}
}
exit:
g_strfreev(substrings);
return sock_fds;
}
/*
* The exported init function.
*
* ... -netdev af-xdp,ifname="..."
*/
int net_init_af_xdp(const Netdev *netdev,
const char *name, NetClientState *peer, Error **errp)
{
const NetdevAFXDPOptions *opts = &netdev->u.af_xdp;
NetClientState *nc, *nc0 = NULL;
unsigned int ifindex;
uint32_t prog_id = 0;
int *sock_fds = NULL;
int64_t i, queues;
Error *err = NULL;
AFXDPState *s;
ifindex = if_nametoindex(opts->ifname);
if (!ifindex) {
error_setg_errno(errp, errno, "failed to get ifindex for '%s'",
opts->ifname);
return -1;
}
queues = opts->has_queues ? opts->queues : 1;
if (queues < 1) {
error_setg(errp, "invalid number of queues (%" PRIi64 ") for '%s'",
queues, opts->ifname);
return -1;
}
if ((opts->has_inhibit && opts->inhibit) != !!opts->sock_fds) {
error_setg(errp, "'inhibit=on' requires 'sock-fds' and vice versa");
return -1;
}
if (opts->sock_fds) {
sock_fds = parse_socket_fds(opts->sock_fds, queues, errp);
if (!sock_fds) {
return -1;
}
}
for (i = 0; i < queues; i++) {
nc = qemu_new_net_client(&net_af_xdp_info, peer, "af-xdp", name);
qemu_set_info_str(nc, "af-xdp%"PRIi64" to %s", i, opts->ifname);
nc->queue_index = i;
if (!nc0) {
nc0 = nc;
}
s = DO_UPCAST(AFXDPState, nc, nc);
pstrcpy(s->ifname, sizeof(s->ifname), opts->ifname);
s->ifindex = ifindex;
s->n_queues = queues;
if (af_xdp_umem_create(s, sock_fds ? sock_fds[i] : -1, errp)
|| af_xdp_socket_create(s, opts, errp)) {
/* Make sure the XDP program will be removed. */
s->n_queues = i;
error_propagate(errp, err);
goto err;
}
}
if (nc0) {
s = DO_UPCAST(AFXDPState, nc, nc0);
if (bpf_xdp_query_id(s->ifindex, s->xdp_flags, &prog_id) || !prog_id) {
error_setg_errno(errp, errno,
"no XDP program loaded on '%s', ifindex: %d",
s->ifname, s->ifindex);
goto err;
}
}
af_xdp_read_poll(s, true); /* Initially only poll for reads. */
return 0;
err:
g_free(sock_fds);
if (nc0) {
qemu_del_net_client(nc0);
}
return -1;
}