From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mails.dpdk.org (mails.dpdk.org [217.70.189.124]) by inbox.dpdk.org (Postfix) with ESMTP id C13D9A0C41; Wed, 15 Sep 2021 10:34:47 +0200 (CEST) Received: from [217.70.189.124] (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id B0512410ED; Wed, 15 Sep 2021 10:34:47 +0200 (CEST) Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by mails.dpdk.org (Postfix) with ESMTP id DD8264003C; Wed, 15 Sep 2021 10:34:46 +0200 (CEST) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 661066D; Wed, 15 Sep 2021 01:34:46 -0700 (PDT) Received: from net-arm-n1amp-02.shanghai.arm.com (net-arm-n1amp-02.shanghai.arm.com [10.169.210.110]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 0C4273F719; Wed, 15 Sep 2021 01:34:42 -0700 (PDT) From: Ruifeng Wang To: dev@dpdk.org Cc: beilei.xing@intel.com, qi.z.zhang@intel.com, bruce.richardson@intel.com, jerinj@marvell.com, hemant.agrawal@nxp.com, drc@linux.vnet.ibm.com, honnappa.nagarahalli@arm.com, stable@dpdk.org, nd@arm.com, Ruifeng Wang Date: Wed, 15 Sep 2021 16:33:38 +0800 Message-Id: <20210915083339.2424369-2-ruifeng.wang@arm.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210915083339.2424369-1-ruifeng.wang@arm.com> References: <20210906033201.1789796-1-ruifeng.wang@arm.com> <20210915083339.2424369-1-ruifeng.wang@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Subject: [dpdk-dev] [PATCH v2 1/2] net/i40e: fix risk in Rx descriptor read in NEON vector path X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" Rx descriptor is 16B/32B in size. If the DD bit is set, it indicates that the rest of the descriptor words have valid values. Hence, the word containing DD bit must be read first before reading the rest of the descriptor words. In NEON vector PMD, vector load loads two contiguous 8B of descriptor data into vector register. Given vector load ensures no 16B atomicity, read of the word that includes DD field could be reordered after read of other words. In this case, some words could contain invalid data. Read barrier is added after read of qword1 that includes DD field. And qword0 is reloaded to update vector register. This ensures that the fetched data is correct. Testpmd single core test on N1SDP/ThunderX2 showed no performance drop. Fixes: ae0eb310f253 ("net/i40e: implement vector PMD for ARM") Cc: stable@dpdk.org Signed-off-by: Ruifeng Wang Reviewed-by: Honnappa Nagarahalli --- drivers/net/i40e/i40e_rxtx_vec_neon.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/drivers/net/i40e/i40e_rxtx_vec_neon.c b/drivers/net/i40e/i40e_rxtx_vec_neon.c index b2683fda60..71191c7cc8 100644 --- a/drivers/net/i40e/i40e_rxtx_vec_neon.c +++ b/drivers/net/i40e/i40e_rxtx_vec_neon.c @@ -286,6 +286,14 @@ _recv_raw_pkts_vec(struct i40e_rx_queue *__rte_restrict rxq, descs[1] = vld1q_u64((uint64_t *)(rxdp + 1)); descs[0] = vld1q_u64((uint64_t *)(rxdp)); + /* Use acquire fence to order loads of descriptor qwords */ + rte_atomic_thread_fence(__ATOMIC_ACQUIRE); + /* A.2 reload qword0 to make it ordered after qword1 load */ + descs[3] = vld1q_lane_u64((uint64_t *)(rxdp + 3), descs[3], 0); + descs[2] = vld1q_lane_u64((uint64_t *)(rxdp + 2), descs[2], 0); + descs[1] = vld1q_lane_u64((uint64_t *)(rxdp + 1), descs[1], 0); + descs[0] = vld1q_lane_u64((uint64_t *)(rxdp), descs[0], 0); + /* B.1 load 4 mbuf point */ mbp1 = vld1q_u64((uint64_t *)&sw_ring[pos]); mbp2 = vld1q_u64((uint64_t *)&sw_ring[pos + 2]); -- 2.25.1