From: Alex Williamson <alex.williamson@redhat.com>
To: Stephen Hemminger <stephen@networkplumber.org>
Cc: dev@dpdk.org, Avi Kivity <avi@scylladb.com>
Subject: Re: [dpdk-dev] [PATCH] vfio: support iommu group zero
Date: Wed, 09 Dec 2015 18:52:00 -0700 [thread overview]
Message-ID: <1449712320.15753.480.camel@redhat.com> (raw)
In-Reply-To: <20151209165216.778bf9e3@xeon-e3>
On Wed, 2015-12-09 at 16:52 -0800, Stephen Hemminger wrote:
> On Wed, 09 Dec 2015 16:22:14 -0700
> Alex Williamson <alex.williamson@redhat.com> wrote:
>
> > On Wed, 2015-12-09 at 15:12 -0800, Stephen Hemminger wrote:
> > > On Wed, 09 Dec 2015 23:49:59 +0100
> > > Thomas Monjalon <thomas.monjalon@6wind.com> wrote:
> > >
> > > > 2015-12-09 13:58, Stephen Hemminger:
> > > > > On Wed, 09 Dec 2015 22:12:33 +0100
> > > > > Thomas Monjalon <thomas.monjalon@6wind.com> wrote:
> > > > >
> > > > > > 2015-12-09 09:55, Stephen Hemminger:
> > > > > > > The current implementation of VFIO will not with the new no-IOMMU mode
> > > > > > > in 4.4 kernel. The original code assumed that IOMMU group zero would
> > > > > > > never be used. Group numbers are assigned starting at zero, and up
> > > > > > > until now the group numbers came from the hardware which is likely
> > > > > > > to use group 0 for system devices that are not used with DPDK.
> > > > > > >
> > > > > > > The fix is to allow 0 as a valid group and rearrange code
> > > > > > > to split the return value from the group value.
> > > > > > >
> > > > > > > Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
> > > > > > > ---
> > > > > > > Why was this ignored? It was originally sent on 26 Oct 15 back
> > > > > > > when IOMMU discussion was lively.
> > > > > >
> > > > > > There was no review of this patch.
> > > > > > The patch has been marked as deferred recently when it was too late
> > > > > > to do such feature changes in DPDK code:
> > > > > > http://dpdk.org/dev/patchwork/patch/8035/
> > > > >
> > > > > This is why as a fallback the MAINTAINER has to review the patch
> > > > > or direct a sub-maintainer to do it. I think almost 2 months is
> > > > > plenty of time for review.
> > > >
> > > > 27 October was 3 days before the feature deadline.
> > > > And you have not pinged about it since then.
> > > > But that's true I have missed the importance of this patch.
> > > > Would it help to have it integrated today?
> > > > Are you sure it won't break something else?
> > >
> > > Could the original VFIO submitter from Intel review it.
> >
> > vfio group 0 has always been valid, but it's unlikely that you'd ever
> > hit it in regular usage since it will typically be the root bus device.
> > It's only with no-iommu mode in vfio that it's common, but that's
> > getting reverted for Linux v4.4, so that may change your priorities
> > about squeezing this in at the last minute. Thanks,
>
> Why, who objected? It was useful and working fine as far as I tested.
> Really wanted to get to the per-queue stuff, but that was harder to
> got working (even on regular IOMMU).
I objected because nobody has spoken up for the month that I've been
asking to be notified if a user has been tested. You can ask for it
again in v4.5 with evidence showing that it works and meets your needs.
next prev parent reply other threads:[~2015-12-10 1:52 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-09 17:55 Stephen Hemminger
2015-12-09 21:12 ` Thomas Monjalon
2015-12-09 21:51 ` Stephen Hemminger
2015-12-09 21:58 ` Stephen Hemminger
2015-12-09 22:49 ` Thomas Monjalon
2015-12-09 23:12 ` Stephen Hemminger
2015-12-09 23:22 ` Alex Williamson
2015-12-10 0:52 ` Stephen Hemminger
2015-12-10 1:52 ` Alex Williamson [this message]
2015-12-10 9:57 ` Burakov, Anatoly
2015-12-10 20:30 ` Thomas Monjalon
-- strict thread matches above, loose matches on Subject: below --
2015-10-27 2:34 Stephen Hemminger
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