Re: [PATCH 2/2] virtio: change io privilege level as early as possible

[David Marchand <david.marchand@6wind.com>]

On Wed, Oct 14, 2015 at 2:07 AM, Stephen Hemminger <
stephen@networkplumber.org> wrote:

> 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:
>
> > > 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.
>

I am testing Thomas proposal (just moving the intr_init() call), else I
will rebase this patch.

-- 
David Marchand