From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: <stephen@networkplumber.org> Received: from mail-pa0-f49.google.com (mail-pa0-f49.google.com [209.85.220.49]) by dpdk.org (Postfix) with ESMTP id A23568D9D for <dev@dpdk.org>; Wed, 14 Oct 2015 02:06:55 +0200 (CEST) Received: by pacex6 with SMTP id ex6so35422655pac.3 for <dev@dpdk.org>; Tue, 13 Oct 2015 17:06:55 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:date:from:to:cc:subject:message-id:in-reply-to :references:mime-version:content-type:content-transfer-encoding; bh=UbNGCxtgZ2RWcOsLPlzRK8Hh347UitmCFpocDxpfnPo=; b=j50lAmdwzGvBfEj5KOO/jnFkQp8h67WpVnPcwqkchgZI9bU+g69WC9SqKJL1wCQsWL W9faK5anDASNtQ3UYwagLrZilYWGiVLlFv7TVW99lYxOxNiVgl5m0NXe0Jk55SF4H4XQ oO80G1vYwi5P5DJY4509kFDZfpQ0cT1kJ7b2A77EDwgAqZ4iaKx2NADJS4M2VIoY9qj5 1P1PWCZzQsWd+I3aEWetRv8kK3Gpj8wBkXg4XQnO3koma04CNsHuZoiy16NnNwEhKDrT ol6fqT2sUsTsIG4lwqO13MTPgjFa9TfRbROZGq5B1prXMCNuZmmaoD9CgHLpGhSVRy36 Fj4Q== X-Gm-Message-State: ALoCoQk2VsJ6DIJwuD7Wz6O49ecrruJ0v7/VbiR99u7OGmHcfZQRV6xee/DXcta7Fp+HjHqagB+u X-Received: by 10.66.162.168 with SMTP id yb8mr286639pab.48.1444781214962; Tue, 13 Oct 2015 17:06:54 -0700 (PDT) Received: from xeon-e3 (static-50-53-82-155.bvtn.or.frontiernet.net. [50.53.82.155]) by smtp.gmail.com with ESMTPSA id vm6sm5964509pbc.8.2015.10.13.17.06.54 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 13 Oct 2015 17:06:54 -0700 (PDT) Date: Tue, 13 Oct 2015 17:07:06 -0700 From: Stephen Hemminger <stephen@networkplumber.org> To: Neil Horman <nhorman@tuxdriver.com> Message-ID: <20151013170706.376bbdd8@xeon-e3> In-Reply-To: <20151001112545.GC4537@hmsreliant.think-freely.org> References: <CALwxeUuQtv685KnbmpZKCPkrAqmjLs558xeCW7c=-TPTsB423w@mail.gmail.com> <CALwxeUuiFpPKeSOh11ANmJwbkTi3fSO6AVAi-TLWBNs0nTP66g@mail.gmail.com> <20150930145202.GE32524@hmsreliant.think-freely.org> <2615920.hxcAs4lYm6@xps13> <20151001112545.GC4537@hmsreliant.think-freely.org> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: dev@dpdk.org Subject: Re: [dpdk-dev] [PATCH 2/2] virtio: change io privilege level as early as possible X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches and discussions about DPDK <dev.dpdk.org> List-Unsubscribe: <http://dpdk.org/ml/options/dev>, <mailto:dev-request@dpdk.org?subject=unsubscribe> List-Archive: <http://dpdk.org/ml/archives/dev/> List-Post: <mailto:dev@dpdk.org> List-Help: <mailto:dev-request@dpdk.org?subject=help> List-Subscribe: <http://dpdk.org/ml/listinfo/dev>, <mailto:dev-request@dpdk.org?subject=subscribe> X-List-Received-Date: Wed, 14 Oct 2015 00:06:56 -0000 On Thu, 1 Oct 2015 07:25:45 -0400 Neil Horman <nhorman@tuxdriver.com> wrote: > On Wed, Sep 30, 2015 at 05:37:05PM +0200, Thomas Monjalon wrote: > > 2015-09-30 10:52, Neil Horman: > > > On Wed, Sep 30, 2015 at 10:28:53AM +0200, David Marchand wrote: > > > > On Tue, Sep 29, 2015 at 9:25 PM, Stephen Hemminger < > > > > stephen@networkplumber.org> wrote: > > > > > > > > > On Tue, 10 Mar 2015 09:14:28 -0400 > > > > > Neil Horman <nhorman@tuxdriver.com> wrote: > > > > > > I don't see how this works for all cases. The constructor is called > > > > > once when > > > > > > the library is first loaded. What if you have multiple independent > > > > > (i.e. not > > > > > > forked children) processes that are using the dpdk in parallel? Only the > > > > > > process that triggered the library load will have io permissions set > > > > > > appropriately. I think what you need is to have every application that > > > > > expects > > > > > > to call through the transmit path or poll the receive path call iopl, > > > > > which I > > > > > > think speaks to having this requirement documented, so each application > > > > > can call > > > > > > iopl prior to calling fork/daemonize/etc. > > > > > > > > > > > > > > > > I am still seeing this problem with DPDK 2.0 and 2.1. > > > > > It seems to me that doing the iopl init in eal_init is the only safe way. > > > > > Other workaround is to have application calling iopl_init before eal_init > > > > > but that kind of violates the current method of all things being > > > > > initialized by eal_init > > > > > > > > Putting it in the virtio pmd constructor is my preferred solution and we > > > > don't need to pollute the eal for virtio (specific to x86, btw). > > > > > > Preferred solution or not, you can't just call iopl from the constructor, > > > because not all process will get appropriate permissions. It needs to be called > > > by every process. What Stephen is saying is that your solution has use cases > > > for which it doesn't work, and that needs to be solved. > > > > I think it may be solved by calling iopl in the constructor. > > We just need an extra call in rte_virtio_pmd_init() to detect iopl failures. > > We can also simply move rte_eal_intr_init() after rte_eal_dev_init(). > > Please read my previous post on this topic: > > http://thread.gmane.org/gmane.comp.networking.dpdk.devel/14761/focus=22341 > > > > About the multiprocess case, I don't see the problem as the RX/TX and interrupt > > threads are forked in the rte_eal_init() context which should call iopl even in > > secondary processes. > > > > I'm not talking about secondary processes here (i.e. processes forked from a > parent that was the process which initialized the dpdk). I'm referring to two > completely independent processes, both of which link to and use the dpdk. > > Though I think we're saying the same thing. When you say 'constructor' above, > you don't mean 'constructor' in the strict sense, but rather the pmd init > routine (the one called from rte_eal_vdev_init and rte_eal_dev_init). If this > is the case, then yes, that works fine, since each process linking to the DPDK > will enter those routines and call iopl. In fact, if thats the case, then no > call is needed in the constructor at all. I think this patch should be rebased and resubmitted for 2.2. It fixes a real problem (virtio link state). The driver changed directory and the the patch could be redone to minimize changes.