linux-kernel - Re: IOMMU+DMAR causing NMIs-s (was: 4.7-rc6: NMI in intel

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Date:	Wed, 13 Jul 2016 08:48:30 -0600
From:	Alex Williamson <alex.williamson@...hat.com>
To:	Joerg Roedel <joro@...tes.org>
Cc:	Meelis Roos <mroos@...ux.ee>, iommu@...ts.linux-foundation.org,
	David Woodhouse <dwmw2@...radead.org>,
	Linux Kernel list <linux-kernel@...r.kernel.org>
Subject: Re: IOMMU+DMAR causing NMIs-s (was: 4.7-rc6: NMI in intel_idle on
 HP Proliant G6)

On Wed, 13 Jul 2016 12:18:59 +0200
Joerg Roedel <joro@...tes.org> wrote:

> On Wed, Jul 13, 2016 at 12:58:24PM +0300, Meelis Roos wrote:
> > > > Just got http://kodu.ut.ee/~mroos/4.6-dmar-fault2.png when playing with 
> > > > BIOS settings (disabling NUMA). It is the first time I see at least some 
> > > > info in NMI decode.  
> > > 
> > > This looks interesting. Can you please post output of 'lspci -vvv' and
> > > 'lspci -t'?  
> > 
> > Here.  
> 
> Thanks. So device 00:1e.0 is a PCI-bridge which has some 32-bit
> PCI-devices behind it. One of these devices tries to read address
> 0xb000, which is blocked by the IOMMU and causes the fault seen in the
> screen-shot. The fault also causes a PCI-error which is then reported
> through the NMI, causing your kernel panic.
> 
> So the 32bit PCI devices behind the bridge are:
> 
> 01:03.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] ES1000 (rev 02) (prog-if 00 [VGA controller])
> 01:04.0 System peripheral: Compaq Computer Corporation Integrated Lights Out Controller (rev 03)
> 01:04.2 System peripheral: Compaq Computer Corporation Integrated Lights Out  Processor (rev 03)
> 01:04.4 USB controller: Hewlett-Packard Company Integrated Lights-Out Standard Virtual USB Controller (prog-if 00 [UHCI])
> 01:04.6 IPMI SMIC interface: Hewlett-Packard Company Integrated Lights-Out Standard KCS Interface (prog-if 01)
> 
> Can you try to disable this 'Lights Out' processor? Maybe it is causing
> the issues. On the other side, the radeon driver for the ATI card is
> also know for causing faults from time to time. Can you capture the
> kernel messages right before a crash too?

IIRC, blacklisting the hpwdt module can defuse those NMIs and might
help us see more of the actual DMAR faults.  Blacklist in modprobe.d
and rebuild initrd. Thanks,

Alex

PS - never assume BIOS release notes are actually complete