From b5900dff14e5a8334766de6b37629c8020c6bbb0 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Daniel=20P=2E=20Berrang=C3=A9?= Date: Wed, 23 Oct 2024 09:51:01 +0100 Subject: [PATCH] hw/net: report errors from failing to use eBPF RSS FDs MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Signed-off-by: Jason Wang --- hw/net/virtio-net.c | 41 +++++++++++++++++++++++++++++------------ 1 file changed, 29 insertions(+), 12 deletions(-) diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c index 289fba8152..c08ae55424 100644 --- a/hw/net/virtio-net.c +++ b/hw/net/virtio-net.c @@ -1316,28 +1316,27 @@ static void virtio_net_disable_rss(VirtIONet *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 ret = true; int i = 0; if (n->nr_ebpf_rss_fds != EBPF_RSS_MAX_FDS) { - warn_report("Expected %d file descriptors but got %d", - EBPF_RSS_MAX_FDS, n->nr_ebpf_rss_fds); - return false; - } + error_setg(errp, "Expected %d file descriptors but got %d", + EBPF_RSS_MAX_FDS, n->nr_ebpf_rss_fds); + return false; + } for (i = 0; i < n->nr_ebpf_rss_fds; i++) { - fds[i] = monitor_fd_param(monitor_cur(), n->ebpf_rss_fds[i], - &error_warn); + fds[i] = monitor_fd_param(monitor_cur(), n->ebpf_rss_fds[i], errp); if (fds[i] < 0) { ret = false; 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: if (!ret) { @@ -1349,13 +1348,15 @@ exit: return ret; } -static bool virtio_net_load_ebpf(VirtIONet *n) +static bool virtio_net_load_ebpf(VirtIONet *n, Error **errp) { bool ret = false; if (virtio_net_attach_ebpf_to_backend(n->nic, -1)) { - if (!(n->ebpf_rss_fds && virtio_net_load_ebpf_fds(n))) { - ret = ebpf_rss_load(&n->ebpf_rss, NULL); + if (n->ebpf_rss_fds) { + 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); 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); + } + } } }