RE: vfio issue in qemu 2.5

["Goutham GS" <goutham@zadarastorage.com>]

Hello Alex,

Thanks a tonne. We will backport the fix.

Regards,
Goutham.

-----Original Message-----
From: Alex Williamson [mailto:alex.williamson@redhat.com] 
Sent: Friday, February 5, 2016 11:32 AM
To: Goutham GS <goutham@zadarastorage.com>
Cc: kvm@vger.kernel.org
Subject: Re: vfio issue in qemu 2.5

On Fri, 5 Feb 2016 10:49:23 +0530
"Goutham GS" <goutham@zadarastorage.com> wrote:

> Hello Alex,
> 
> Sorry, I got the timestamps wrong yesterday.
> 
> I see the following messages in kern.log at the time of the issue:
> 
> Jan 31 03:46:39 qa2-sn2 kernel: [228419.858857] vfio-pci 0000:04:01.4:
> enabling device (0000 -> 0002)
> Jan 31 03:46:39 qa2-sn2 kernel: [228419.970492] vfio-pci 0000:04:02.7:
> enabling device (0000 -> 0002)
> Jan 31 03:46:39 qa2-sn2 kernel: [228420.082435] IOMMU: no free domain 
> ids Jan 31 03:46:39 qa2-sn2 kernel: [228420.124440] IOMMU: no free 
> domain ids
> 
> Does this say anything?

That's kind of a big deal.  Kernel v3.17 introduced a domain ID leak that
didn't get fully fixed until kernel v4.2.  To make matters worse, even
though the fixes were tagged for stable, the last one doesn't seem to have
been backported to any pre-4.2 stable series.  Long story short, you'll need
to move to v4.2 or backport this to your kernel:

https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=4
6ebb7af7b93792de65e124e1ab8b89a108a41f2

Thanks,
Alex