From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from dpdk.org (dpdk.org [92.243.14.124]) by inbox.dpdk.org (Postfix) with ESMTP id 7FC2DA0525; Fri, 21 Feb 2020 17:26:55 +0100 (CET) Received: from [92.243.14.124] (localhost [127.0.0.1]) by dpdk.org (Postfix) with ESMTP id 667A81BFAC; Fri, 21 Feb 2020 17:26:54 +0100 (CET) Received: from inbox.dpdk.org (xvm-172-178.dc0.ghst.net [95.142.172.178]) by dpdk.org (Postfix) with ESMTP id B56C51BFA9 for ; Fri, 21 Feb 2020 17:26:53 +0100 (CET) Received: by inbox.dpdk.org (Postfix, from userid 33) id 8DC18A0551; Fri, 21 Feb 2020 17:26:53 +0100 (CET) From: bugzilla@dpdk.org To: dev@dpdk.org Date: Fri, 21 Feb 2020 16:26:53 +0000 X-Bugzilla-Reason: AssignedTo X-Bugzilla-Type: new X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: DPDK X-Bugzilla-Component: ethdev X-Bugzilla-Version: 19.11 X-Bugzilla-Keywords: X-Bugzilla-Severity: critical X-Bugzilla-Who: scott_wasson@affirmednetworks.com X-Bugzilla-Status: UNCONFIRMED X-Bugzilla-Resolution: X-Bugzilla-Priority: Normal X-Bugzilla-Assigned-To: dev@dpdk.org X-Bugzilla-Target-Milestone: --- X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: bug_id short_desc product version rep_platform op_sys bug_status bug_severity priority component assigned_to reporter target_milestone Message-ID: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bugzilla-URL: http://bugs.dpdk.org/ Auto-Submitted: auto-generated X-Auto-Response-Suppress: All MIME-Version: 1.0 Subject: [dpdk-dev] [Bug 405] mlx5: the guest driver doesn't enforce the MTU set by rte_eth_dev_set_mtu() X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 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" https://bugs.dpdk.org/show_bug.cgi?id=3D405 Bug ID: 405 Summary: mlx5: the guest driver doesn't enforce the MTU set by rte_eth_dev_set_mtu() Product: DPDK Version: 19.11 Hardware: All OS: All Status: UNCONFIRMED Severity: critical Priority: Normal Component: ethdev Assignee: dev@dpdk.org Reporter: scott_wasson@affirmednetworks.com Target Milestone: --- On our guest VM, we are seeing packets that exceed the configured MTU are n= ot dropped by the mlx5 driver, and the packet scribbles past the end of the bu= ffer and overwrites the next struct rte_mbuf in memory. The Openstack host=E2=80=99s MTU is 9000 on the PF. Any large value will d= o. The guest has buffers that are all 2250 bytes in payload size. The guest calls rte_eth_dev_set_mtu() with a value of 2250 on a given VF. We send an ICMP echo packet of size 3000 bytes, and it is not dropped by the driver. Instead, the 3000-byte packet is written into a 2250-byte buffer, having ignored the setting from rte_eth_dev_set_mtu (which had returned =E2=80=9Csuccess=E2=80=9D), and causes corruption of the next struct rte_mb= uf in memory, and a crash very soon thereafter. When we reduce the host=E2=80=99s MTU on the PF to a value <=3D 2250, then = the problem goes away. But we see this is a work-around, not a fix. If the guest is in fact unable to change the MTU due to hardware architectu= ral limitations, it would be prudent to return the error (-ENOTSUP) to indicate that the guest is unable to perform the request. Also generate a log messa= ge describing the reason for the error, to provide the community with sufficie= nt information to understand the problem. But this is speculation, we don't k= now for certain that the mlx5 guest driver is architecturally unable to enforce MTU. --=20 You are receiving this mail because: You are the assignee for the bug.=