From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by mail.toke.dk (Postfix) with ESMTPS id 2E4CB9E63C4 for ; Wed, 1 Feb 2023 18:32:00 +0100 (CET) Authentication-Results: mail.toke.dk; dkim=pass (1024-bit key; unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=ZJXU+QsY DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1675272719; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=C4dv67rjWbB8phkwR88pNNn9RFMxdY5vO814eYDknDc=; b=ZJXU+QsYxvlpJLTtpUR79rY2p86EXJVCY90QBiTBAqa82qUM9G3QLUN4mhRzRzWII/21Ez cwJH0yQCw4v8FHEL8XkMbpM1dtdydq1AKvB+0M/HVFtSFEcv7Bk2ci2dR7MYOQdXOb3GHt ekjn0YIfCIRGVWEHFmp4qxHcMkcq3v8= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-633-OfAtXXwYOJegtnh4WYXY2w-1; Wed, 01 Feb 2023 12:31:54 -0500 X-MC-Unique: OfAtXXwYOJegtnh4WYXY2w-1 Received: from smtp.corp.redhat.com (int-mx09.intmail.prod.int.rdu2.redhat.com [10.11.54.9]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 898563C0F68C; Wed, 1 Feb 2023 17:31:51 +0000 (UTC) Received: from firesoul.localdomain (ovpn-208-9.brq.redhat.com [10.40.208.9]) by smtp.corp.redhat.com (Postfix) with ESMTP id 45037492B05; Wed, 1 Feb 2023 17:31:51 +0000 (UTC) Received: from [192.168.42.3] (localhost [IPv6:::1]) by firesoul.localdomain (Postfix) with ESMTP id 4F142300005EE; Wed, 1 Feb 2023 18:31:50 +0100 (CET) From: Jesper Dangaard Brouer To: bpf@vger.kernel.org, Stanislav Fomichev Date: Wed, 01 Feb 2023 18:31:50 +0100 Message-ID: <167527271027.937063.5177725618616476592.stgit@firesoul> In-Reply-To: <167527267453.937063.6000918625343592629.stgit@firesoul> References: <167527267453.937063.6000918625343592629.stgit@firesoul> User-Agent: StGit/1.4 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 3.1 on 10.11.54.9 Message-ID-Hash: ALX7DGIFOE2HA54O5OZMEITZK2GENMZM X-Message-ID-Hash: ALX7DGIFOE2HA54O5OZMEITZK2GENMZM X-MailFrom: brouer@redhat.com X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header CC: Jesper Dangaard Brouer , netdev@vger.kernel.org, martin.lau@kernel.org, ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, martin.lau@linux.dev, song@kernel.org, yhs@fb.com, john.fastabend@gmail.com, dsahern@gmail.com, willemb@google.com, void@manifault.com, kuba@kernel.org, xdp-hints@xdp-project.net X-Mailman-Version: 3.3.8 Precedence: list Subject: [xdp-hints] [PATCH bpf-next V2 1/4] selftests/bpf: xdp_hw_metadata clear metadata when -EOPNOTSUPP List-Id: XDP hardware hints design discussion Archived-At: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: The AF_XDP userspace part of xdp_hw_metadata see non-zero as a signal of the availability of rx_timestamp and rx_hash in data_meta area. The kernel-side BPF-prog code doesn't initialize these members when kernel returns an error e.g. -EOPNOTSUPP. This memory area is not guaranteed to be zeroed, and can contain garbage/previous values, which will be read and interpreted by AF_XDP userspace side. Tested this on different drivers. The experiences are that for most packets they will have zeroed this data_meta area, but occasionally it will contain garbage data. Example of failure tested on ixgbe: poll: 1 (0) xsk_ring_cons__peek: 1 0x18ec788: rx_desc[0]->addr=100000000008000 addr=8100 comp_addr=8000 rx_hash: 3697961069 rx_timestamp: 9024981991734834796 (sec:9024981991.7348) 0x18ec788: complete idx=8 addr=8000 Converting to date: date -d @9024981991 2255-12-28T20:26:31 CET I choose a simple fix in this patch. When kfunc fails or isn't supported assign zero to the corresponding struct meta value. It's up to the individual BPF-programmer to do something smarter e.g. that fits their use-case, like getting a software timestamp and marking a flag that gives the type of timestamp. Fixes: 297a3f124155 ("selftests/bpf: Simple program to dump XDP RX metadata") Signed-off-by: Jesper Dangaard Brouer --- .../testing/selftests/bpf/progs/xdp_hw_metadata.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/tools/testing/selftests/bpf/progs/xdp_hw_metadata.c b/tools/testing/selftests/bpf/progs/xdp_hw_metadata.c index 25b8178735ee..4c55b4d79d3d 100644 --- a/tools/testing/selftests/bpf/progs/xdp_hw_metadata.c +++ b/tools/testing/selftests/bpf/progs/xdp_hw_metadata.c @@ -70,10 +70,14 @@ int rx(struct xdp_md *ctx) } if (!bpf_xdp_metadata_rx_timestamp(ctx, &meta->rx_timestamp)) - bpf_printk("populated rx_timestamp with %u", meta->rx_timestamp); + bpf_printk("populated rx_timestamp with %llu", meta->rx_timestamp); + else + meta->rx_timestamp = 0; /* Used by AF_XDP as not avail signal */ if (!bpf_xdp_metadata_rx_hash(ctx, &meta->rx_hash)) bpf_printk("populated rx_hash with %u", meta->rx_hash); + else + meta->rx_hash = 0; /* Used by AF_XDP as not avail signal */ return bpf_redirect_map(&xsk, ctx->rx_queue_index, XDP_PASS); }