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

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Message-ID: <alpine.LRH.2.20.1607131206430.20366@math.ut.ee>
Date:	Wed, 13 Jul 2016 12:16:46 +0300 (EEST)
From:	Meelis Roos <mroos@...ux.ee>
To:	Joerg Roedel <joro@...tes.org>
cc:	iommu@...ts.linux-foundation.org,
	Linux Kernel list <linux-kernel@...r.kernel.org>,
	David Woodhouse <dwmw2@...radead.org>
Subject: Re: IOMMU+DMAR causing NMIs-s (was: 4.7-rc6: NMI in intel_idle on
 HP Proliant G6)

> > > > Bisecting kernel configs shows that it's DMAR+IOMMU. When it is 
> > > > activated, there is high probability of NMI-s in random places.
> > > 
> > > Hmm, strange. But nothing could really surprise when you have an HP
> > > BIOS.
> > 
> > BIOS P64 01/22/2015. There seems to be a newer 2015.08.16 BIOS out but 
> > the release notes only describe updated CPU microcode for security 
> > reasons.
> 
> It is probably something HP is selling as a "feature" and not a BIOS
> bug.

ROM setup settings that might be of interest:

Advanced memory protection: advanced ecc support
No-Execute memory protection: enabled
Intel virtualization technology: enabled
Intel hyperthreading options: enabled
Processor core disable: all cored enabled
Intel turbo boost technology: enabled
Intel VT-d: enabled
HP power profile: custom
HP power regulator: hp dynamic power savings mode (not OS control)
Intel qpi link power management: enabled
Minimum processor idle power core state: C6
Minimum processor idle power package state: C6
Dynamic power saving mode response: fast
Collaborative power control: enabled
MPS table: full table apic
NMI debug button: enabled
PCI bus padding options: enabled
HW prefetcher: enabled
Adjacent sector prefetch: enabled
Node interleaving: disabled


> > > Can you probably use the faulty config and bisect this down to a
> > > specific commit? In v4.7-rc1 some changes to the iova-allocation code
> > > got merged, but I have no idea how those could cause NMIs.
> > 
> > Will try but I do not know a working base yet - this was broken in both 
> > 4.6 and 4.7-rc.
> 
> Oh, in that case it is not related to the recent iova changes. Does the
> box have any hardware error log which you can access and send to us
> (right after some NMIs happened)?

Nothing in ILO log or integrated management log (IML).

-- 
Meelis Roos (mroos@...ux.ee)