From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 099AFC33CB6 for ; Thu, 23 Jan 2020 16:59:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CBECA21D7E for ; Thu, 23 Jan 2020 16:59:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579798748; bh=kSGcMTzAf4NiR0SgzGIPmzGXO+zaWusO8GxX42p0iIc=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=kCw0j+jDGMDPQWzi3oNDzVN2R5ZB3jtOt0HUYT0uhUCEt6XQIcKz1fQBHAOAeys12 aUTel8tqMFmAyazIDDfx/K6z7YSfDY+dfEuCQY1oe3KU1oThWObHokh+s4Nqtjzmh/ MXh4cL7oETDSLyYx6j0U7JQ0dweaYGqY9/O8pglQ= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729654AbgAWQ7I (ORCPT ); Thu, 23 Jan 2020 11:59:08 -0500 Received: from mail.kernel.org ([198.145.29.99]:49316 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728731AbgAWQ7H (ORCPT ); Thu, 23 Jan 2020 11:59:07 -0500 Received: from cakuba (unknown [199.201.64.139]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id D5D982071E; Thu, 23 Jan 2020 16:59:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579798747; bh=kSGcMTzAf4NiR0SgzGIPmzGXO+zaWusO8GxX42p0iIc=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=0N8Psd0uums0PGJRB9OdJVzkPo9Mfe++Q1LgNtwD1fi5N1TZBFx8eYEUAjT1pbh63 Sv8OX4mDZmVVfeP9DrbffU9L9jFVm184UokrlZWMMcKzTT62mXb8shjU9Wo3QmjgOO l+TP4ZNPwFb7EcA9dzJv9I3HGCmPRvCCqWrsTZjk= Date: Thu, 23 Jan 2020 08:59:06 -0800 From: Jakub Kicinski To: Haiyang Zhang Cc: sashal@kernel.org, linux-hyperv@vger.kernel.org, netdev@vger.kernel.org, kys@microsoft.com, sthemmin@microsoft.com, olaf@aepfle.de, vkuznets@redhat.com, davem@davemloft.net, linux-kernel@vger.kernel.org Subject: Re: [PATCH V3,net-next, 1/2] hv_netvsc: Add XDP support Message-ID: <20200123085906.20608707@cakuba> In-Reply-To: <1579713814-36061-2-git-send-email-haiyangz@microsoft.com> References: <1579713814-36061-1-git-send-email-haiyangz@microsoft.com> <1579713814-36061-2-git-send-email-haiyangz@microsoft.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 22 Jan 2020 09:23:33 -0800, Haiyang Zhang wrote: > This patch adds support of XDP in native mode for hv_netvsc driver, and > transparently sets the XDP program on the associated VF NIC as well. > > Setting / unsetting XDP program on synthetic NIC (netvsc) propagates to > VF NIC automatically. Setting / unsetting XDP program on VF NIC directly > is not recommended, also not propagated to synthetic NIC, and may be > overwritten by setting of synthetic NIC. > > The Azure/Hyper-V synthetic NIC receive buffer doesn't provide headroom > for XDP. We thought about re-use the RNDIS header space, but it's too > small. So we decided to copy the packets to a page buffer for XDP. And, > most of our VMs on Azure have Accelerated Network (SRIOV) enabled, so > most of the packets run on VF NIC. The synthetic NIC is considered as a > fallback data-path. So the data copy on netvsc won't impact performance > significantly. > > XDP program cannot run with LRO (RSC) enabled, so you need to disable LRO > before running XDP: > ethtool -K eth0 lro off > > XDP actions not yet supported: > XDP_REDIRECT > > Signed-off-by: Haiyang Zhang > > --- > Changes: > v3: Minor code and comment updates. > v2: Added XDP_TX support. Addressed review comments. How does the locking of the TX path work? You seem to be just calling the normal xmit method, but you don't hold the xmit queue lock, so the stack can start xmit concurrently, no?