From: gregkh@linuxfoundation•org (Greg Kroah-Hartman)
To: linux-arm-kernel@lists•infradead.org
Subject: 3.16rc3 multiplatform, Armada 370 and IOMMU: unbootable kernel
Date: Mon, 7 Jul 2014 11:30:02 -0700 [thread overview]
Message-ID: <20140707183002.GA5947@kroah.com> (raw)
In-Reply-To: <20140707105818.GA1101@arch.cereza>
On Mon, Jul 07, 2014 at 07:58:18AM -0300, Ezequiel Garcia wrote:
> On 05 Jul 01:59 PM, Greg Kroah-Hartman wrote:
> > On Sat, Jul 05, 2014 at 12:03:08PM -0300, Ezequiel Garcia wrote:
> > > After following Gregory's stacktrace (also reproduced here):
> > >
> > > [<c02451f8>] (iommu_bus_notifier) from [<c00512e8>] (notifier_call_chain+0x64/0x9c)
> > > [<c00512e8>] (notifier_call_chain) from [<c00514cc>] (__blocking_notifier_call_chain+0x40/0x58)
> > > [<c00514cc>] (__blocking_notifier_call_chain) from [<c00514f8>] (blocking_notifier_call_chain+0x14/0x1c)
> > > [<c00514f8>] (blocking_notifier_call_chain) from [<c01d225c>] (device_add+0x424/0x524)
> > > [<c01d225c>] (device_add) from [<c0186d90>] (pci_device_add+0xec/0x110)
> > > [<c0186d90>] (pci_device_add) from [<c0186e54>] (pci_scan_single_device+0xa0/0xac)
> > >
> > > I added a few printks and found that the problem is that the iommu_bus_notifier is
> > > called for the 'pci' bus type, which has a null iommu_ops.
> > >
> > > On 04 Jul 10:47 AM, Laurent Pinchart wrote:
> > > [..]
> > > >
> > > > We need a quick fix for v3.16, ...
> > >
> > > Therefore, a quick fix would be to simply check for that:
> > >
> > > diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> > > index e5555fc..b712cb2 100644
> > > --- a/drivers/iommu/iommu.c
> > > +++ b/drivers/iommu/iommu.c
> > > @@ -536,6 +536,9 @@ static int iommu_bus_notifier(struct notifier_block *nb,
> > > struct iommu_group *group;
> > > unsigned long group_action = 0;
> > >
> > > + if (!ops)
> > > + return 0;
> > > +
> > > /*
> > > * ADD/DEL call into iommu driver ops if provided, which may
> > > * result in ADD/DEL notifiers to group->notifier
> > >
> > > This (nasty workaround?) patch makes the problem go away.
> > >
> > > [..]
> > > > > So it also boot well in 3.15 and then failed in 3.16-rc3. I hope it will
> > > > > help the developers of the OMAP IOMMU driver to fix it.
> > > >
> > > > Thank you. I've had a look at the OMAP IOMMU driver changes between v3.15 and
> > > > v3.16-rc3, and didn't find at first sight any change that could explain the
> > > > crash.
> > > >
> > > > 286f600 iommu/omap: Fix map protection value handling
> > > > 67b779d iommu/omap: Remove comment about supporting single page mappings only
> > > > f7129a0 iommu/omap: Fix 'no page for' debug message in flush_iotlb_page()
> > > > 5acc97d iommu/omap: Move to_iommu definition from omap-iopgtable.h
> > > > 2ac6133 iommu/omap: Remove omap_iommu_domain_has_cap() function
> > > > d760e3e iommu/omap: Correct init value of iotlb_entry valid field
> > > >
> > > > Could you try reverting those changes and retest ? If the problem doesn't
> > > > disappear, we'll need to look somewhere else.
> > > >
> > >
> > > I reverted the above commits but nothing changed. I'm far from being an expert,
> > > but it sounds odd to have this bus notifier (that got registered for the
> > > platform bus type) called by a pci bus type.
> >
> > Why wouldn't the PCI bus set this up for its devices? Are you
> > "assuming" you know the bus type and that's the issue?
> >
>
> Thanks for looking at this.
>
> I guess I snipped the thread and lost most of the information about the panic.
> Here's the original bug report:
>
> http://www.spinics.net/lists/arm-kernel/msg344059.html
>
> The problem reported involves enabling OMAP IOMMU driver and not any other IOMMU
> driver. Doing some tracing and adding a few prints, we found that
> omap_iommu_init() sets a bus notifier for the platform bus type:
>
> omap_iommu_init -> bus_set_iommu -> iommu_bus_init:
>
> static void iommu_bus_init(struct bus_type *bus, struct iommu_ops *ops)
> {
> bus_register_notifier(bus, &iommu_bus_nb);
> bus_for_each_dev(bus, NULL, ops, add_iommu_group);
> }
>
> But the iommu bus notifier gets called for the 'pci' bus type, which
> has the iommu_ops field NULL (since it hasn't been set for iommu).
So this is what needs to be figured out, how is the notifier being
called with a PCI device? Who else called iommu_bus_init() for the PCI
bus?
thanks,
greg k-h
next prev parent reply other threads:[~2014-07-07 18:30 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-07-03 13:51 3.16rc3 multiplatform, Armada 370 and IOMMU: unbootable kernel Paolo Pisati
2014-07-03 14:27 ` Thomas Petazzoni
2014-07-03 14:57 ` Paolo Pisati
2014-07-03 20:22 ` Gregory CLEMENT
2014-07-03 20:52 ` Thomas Petazzoni
2014-07-03 20:57 ` Gregory CLEMENT
2014-07-03 21:01 ` Thomas Petazzoni
2014-07-03 21:07 ` Gregory CLEMENT
2014-07-03 21:24 ` Gregory CLEMENT
2014-07-04 8:47 ` Laurent Pinchart
2014-07-05 15:03 ` Ezequiel Garcia
2014-07-05 20:59 ` Greg Kroah-Hartman
2014-07-07 10:58 ` Ezequiel Garcia
2014-07-07 18:30 ` Greg Kroah-Hartman [this message]
2014-07-07 23:37 ` Ezequiel Garcia
2014-07-07 23:47 ` Greg Kroah-Hartman
2014-07-08 7:41 ` Thomas Petazzoni
2014-07-08 9:20 ` Paolo Pisati
2014-07-08 12:01 ` Jason Cooper
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20140707183002.GA5947@kroah.com \
--to=gregkh@linuxfoundation$(echo .)org \
--cc=linux-arm-kernel@lists$(echo .)infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox