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hw/net: report errors from failing to use eBPF RSS FDs

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If the user/mgmt app passed in a set of pre-opened FDs for eBPF RSS,
then it is expecting QEMU to use them. Any failure to do so must be
considered a fatal error and propagated back up the stack, otherwise
deployment mistakes will not be detectable in a prompt manner. When
not using pre-opened FDs, then eBPF RSS is tried on a "best effort"
basis only and thus fallback to software RSS is valid.

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
This commit is contained in:
Daniel P. Berrangé 2024-10-23 09:51:01 +01:00 • committed by Jason Wang
parent 00b69f1d86
commit b5900dff14
1 changed files with 29 additions and 12 deletions
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35
hw/net/virtio-net.c
View file

@ -1316,28 +1316,27 @@ static void virtio_net_disable_rss(VirtIONet *n)
virtio_net_commit_rss_config(n); virtio_net_commit_rss_config(n);
} }
static bool virtio_net_load_ebpf_fds(VirtIONet *n) static bool virtio_net_load_ebpf_fds(VirtIONet *n, Error **errp)
{ {
int fds[EBPF_RSS_MAX_FDS] = { [0 ... EBPF_RSS_MAX_FDS - 1] = -1}; int fds[EBPF_RSS_MAX_FDS] = { [0 ... EBPF_RSS_MAX_FDS - 1] = -1};
int ret = true; int ret = true;
int i = 0; int i = 0;
if (n->nr_ebpf_rss_fds != EBPF_RSS_MAX_FDS) { if (n->nr_ebpf_rss_fds != EBPF_RSS_MAX_FDS) {
warn_report("Expected %d file descriptors but got %d", error_setg(errp, "Expected %d file descriptors but got %d",
EBPF_RSS_MAX_FDS, n->nr_ebpf_rss_fds); EBPF_RSS_MAX_FDS, n->nr_ebpf_rss_fds);
return false; return false;
} }
for (i = 0; i < n->nr_ebpf_rss_fds; i++) { for (i = 0; i < n->nr_ebpf_rss_fds; i++) {
fds[i] = monitor_fd_param(monitor_cur(), n->ebpf_rss_fds[i], fds[i] = monitor_fd_param(monitor_cur(), n->ebpf_rss_fds[i], errp);
&error_warn);
if (fds[i] < 0) { if (fds[i] < 0) {
ret = false; ret = false;
goto exit; goto exit;
} }
} }
ret = ebpf_rss_load_fds(&n->ebpf_rss, fds[0], fds[1], fds[2], fds[3], NULL); ret = ebpf_rss_load_fds(&n->ebpf_rss, fds[0], fds[1], fds[2], fds[3], errp);
exit: exit:
if (!ret) { if (!ret) {
@ -1349,13 +1348,15 @@ exit:
return ret; return ret;
} }
static bool virtio_net_load_ebpf(VirtIONet *n) static bool virtio_net_load_ebpf(VirtIONet *n, Error **errp)
{ {
bool ret = false; bool ret = false;
if (virtio_net_attach_ebpf_to_backend(n->nic, -1)) { if (virtio_net_attach_ebpf_to_backend(n->nic, -1)) {
if (!(n->ebpf_rss_fds && virtio_net_load_ebpf_fds(n))) { if (n->ebpf_rss_fds) {
ret = ebpf_rss_load(&n->ebpf_rss, NULL); ret = virtio_net_load_ebpf_fds(n, errp);
} else {
ret = ebpf_rss_load(&n->ebpf_rss, errp);
} }
} }
@ -3761,7 +3762,23 @@ static void virtio_net_device_realize(DeviceState *dev, Error **errp)
net_rx_pkt_init(&n->rx_pkt); net_rx_pkt_init(&n->rx_pkt);
if (virtio_has_feature(n->host_features, VIRTIO_NET_F_RSS)) { if (virtio_has_feature(n->host_features, VIRTIO_NET_F_RSS)) {
virtio_net_load_ebpf(n); Error *err = NULL;
if (!virtio_net_load_ebpf(n, &err)) {
/*
* If user explicitly gave QEMU RSS FDs to use, then
* failing to use them must be considered a fatal
* error. If no RSS FDs were provided, QEMU is trying
* eBPF on a "best effort" basis only, so report a
* warning and allow fallback to software RSS.
*/
if (n->ebpf_rss_fds) {
error_propagate(errp, err);
} else {
warn_report("unable to load eBPF RSS: %s",
error_get_pretty(err));
error_free(err);
}
}
} }
} }