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From: Stephen Hemminger <stephen@networkplumber.org>
To: Neil Horman <nhorman@tuxdriver.com>
Cc: dev@dpdk.org
Subject: Re: [dpdk-dev] [PATCH 2/2] virtio: change io privilege level as early as possible
Date: Tue, 13 Oct 2015 17:07:06 -0700
Message-ID: <20151013170706.376bbdd8@xeon-e3> (raw)
In-Reply-To: <20151001112545.GC4537@hmsreliant.think-freely.org>

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.

  parent reply	other threads:[~2015-10-14  0:06 UTC|newest]

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-03-06  0:45 [dpdk-dev] [PATCH 0/2] virtio: bugfixes Stephen Hemminger
2015-03-06  0:45 ` [dpdk-dev] [PATCH 1/2] virtio: initialize iopl when device is initialized Stephen Hemminger
2015-03-06  3:41   ` Ouyang, Changchun
2015-03-06 16:20     ` Stephen Hemminger
2015-03-06 16:33       ` David Marchand
2015-03-06 16:55         ` Stephen Hemminger
2015-03-06 22:04           ` David Marchand
2015-03-06 23:43             ` Stephen Hemminger
2015-03-07  6:53               ` David Marchand
2015-03-09 11:05       ` David Marchand
2015-03-09 14:56         ` [dpdk-dev] [PATCH 0/2] fix virtio interrupt handling David Marchand
2015-03-09 14:56           ` [dpdk-dev] [PATCH 1/2] eal/linux: move plugin load to very start of eal init David Marchand
2015-03-09 15:21             ` Neil Horman
     [not found]               ` <CALwxeUs4hPbYDPBUfz9u2AoiCoj_wwTsAyj=_1xxzuT6LLW6nw@mail.gmail.com>
2015-03-10 10:55                 ` Neil Horman
2015-10-14  0:05                   ` Stephen Hemminger
2015-10-14  9:55                     ` David Marchand
2015-03-09 14:56           ` [dpdk-dev] [PATCH 2/2] virtio: change io privilege level as early as possible David Marchand
2015-03-10 13:14             ` Neil Horman
2015-09-29 19:25               ` Stephen Hemminger
2015-09-30  8:28                 ` David Marchand
2015-09-30 14:52                   ` Neil Horman
2015-09-30 15:37                     ` Thomas Monjalon
2015-09-30 17:26                       ` Stephen Hemminger
2015-10-01 11:25                       ` Neil Horman
2015-10-12 20:08                         ` Stephen Hemminger
2015-10-14  0:07                         ` Stephen Hemminger [this message]
2015-10-14  8:00                           ` David Marchand
2015-10-14  9:49                             ` David Marchand
2015-10-14  9:50                               ` [dpdk-dev] [PATCH] eal: move interrupt init after device init David Marchand
2015-10-14 11:32                                 ` David Marchand
2015-10-20 21:22                                   ` Thomas Monjalon
2015-07-29 17:26       ` [dpdk-dev] [PATCH 1/2] virtio: initialize iopl when device is initialized Thomas Monjalon
2015-03-06  0:45 ` [dpdk-dev] [PATCH 2/2] virtio: allow running w/o vlan filtering Stephen Hemminger
2015-03-06  3:39   ` Ouyang, Changchun
2015-03-06 16:24     ` Stephen Hemminger
2015-07-29 12:56       ` Thomas Monjalon
2015-07-30  1:23         ` Ouyang, Changchun
2015-08-04 12:51         ` Vincent JARDIN
2015-08-05  1:01           ` Ouyang, Changchun
2015-08-05  1:22             ` Stephen Hemminger
2015-08-05 10:49             ` Vincent JARDIN
2015-10-21 13:58               ` Thomas Monjalon
2017-02-15  8:38                 ` Thomas Monjalon

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