Re: [PATCH 1/2] eal/linux: fix VFIO hotplug with multiprocess

[David Marchand <david.marchand@redhat.com>]

On Tue, Sep 17, 2024 at 10:20 AM Maxime Coquelin
<maxime.coquelin@redhat.com> wrote:
> On 9/16/24 14:30, David Marchand wrote:
> > At the moment, if VFIO is not available at DPDK init, it won't be
> > available unless a subsequent rte_vfio_enable() is done.
> >
> > Yet, even if rte_vfio_enable() is called again in primary and secondary
> > processes, a secondary process will never get to know that VFIO has been
> > enabled in the primary process as the MP requests handler is only
> > registered in EAL init.
> >
> > On the other hand, moving the MP requests handler registration earlier
> > in EAL init is ok, as secondary process are supposed to be waiting on
> > eal_mcfg_wait_complete() until the primary process calls
> > eal_mcfg_complete().
> >
> > Move vfio_mp_sync_setup() in rte_vfio_enable().
> >
> > Besides, rte_eal_vfio_setup() is useless and its name with a rte_ prefix
> > is ambiguous as it gives the impression it is an exported/public symbol.
> > Remove it and directly call rte_vfio_enable() where needed.
> >
> > Signed-off-by: David Marchand <david.marchand@redhat.com>
> > ---
> >   lib/eal/linux/eal.c      | 18 +-----------------
> >   lib/eal/linux/eal_vfio.c |  9 ++++++---
> >   2 files changed, 7 insertions(+), 20 deletions(-)
> >
>
> Should it be considered as a fix, and so a candidate for stable?
> Or do you think it is too risky to change the behaviour?

Cc: stable maintainers (fyi)

I don't think it is risky: existing applications which relied on multi
process had no choice but to make sure VFIO was properly setup before
DPDK init.
Yet, a change in behavior impact is always hard to estimate.

(same comment for the second patch of the series)


-- 
David Marchand