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Tsirkin" , Andrew Melnychenko , =?UTF-8?q?Daniel=20P=2E=20Berrang=C3=A9?= Subject: [PATCH v2 5/7] hw/net: report errors from failing to use eBPF RSS FDs Date: Thu, 5 Sep 2024 19:13:28 +0100 Message-ID: <20240905181330.3657590-6-berrange@redhat.com> In-Reply-To: <20240905181330.3657590-1-berrange@redhat.com> References: <20240905181330.3657590-1-berrange@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=170.10.133.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: 11 X-Spam_score: 1.1 X-Spam_bar: + X-Spam_report: (1.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.142, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_SBL_CSS=3.335, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1725560115874116600 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. Berrang=C3=A9 Reviewed-by: Philippe Mathieu-Daud=C3=A9 --- 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 558fc62844..f2690390c1 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); } =20 -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] =3D { [0 ... EBPF_RSS_MAX_FDS - 1] =3D -1}; int ret =3D true; int i =3D 0; =20 if (n->nr_ebpf_rss_fds !=3D 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; + } =20 for (i =3D 0; i < n->nr_ebpf_rss_fds; i++) { - fds[i] =3D monitor_fd_param(monitor_cur(), n->ebpf_rss_fds[i], - &error_warn); + fds[i] =3D monitor_fd_param(monitor_cur(), n->ebpf_rss_fds[i], err= p); if (fds[i] < 0) { ret =3D false; goto exit; } } =20 - ret =3D ebpf_rss_load_fds(&n->ebpf_rss, fds[0], fds[1], fds[2], fds[3]= , NULL); + ret =3D ebpf_rss_load_fds(&n->ebpf_rss, fds[0], fds[1], fds[2], fds[3]= , errp); =20 exit: if (!ret) { @@ -1349,13 +1348,15 @@ exit: return ret; } =20 -static bool virtio_net_load_ebpf(VirtIONet *n) +static bool virtio_net_load_ebpf(VirtIONet *n, Error **errp) { bool ret =3D false; =20 if (virtio_net_attach_ebpf_to_backend(n->nic, -1)) { - if (!(n->ebpf_rss_fds && virtio_net_load_ebpf_fds(n))) { - ret =3D ebpf_rss_load(&n->ebpf_rss, NULL); + if (n->ebpf_rss_fds) { + ret =3D virtio_net_load_ebpf_fds(n, errp); + } else { + ret =3D ebpf_rss_load(&n->ebpf_rss, errp); } } =20 @@ -3761,7 +3762,23 @@ static void virtio_net_device_realize(DeviceState *d= ev, Error **errp) net_rx_pkt_init(&n->rx_pkt); =20 if (virtio_has_feature(n->host_features, VIRTIO_NET_F_RSS)) { - virtio_net_load_ebpf(n); + Error *err =3D 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); + } + } } } =20 --=20 2.45.2