From: Joerg Roedel <joro@8bytes.org>
To: "Li, Zhen-Hua" <zhen-hual@hp.com>
Cc: David Woodhouse <dwmw2@infradead.org>,
"iommu@lists.linux-foundation.org"
<iommu@lists.linux-foundation.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/1] iommu/vt-d : clear old root entry for dump kernel
Date: Tue, 19 Aug 2014 13:02:39 +0200 [thread overview]
Message-ID: <20140819110239.GA16329@8bytes.org> (raw)
In-Reply-To: <1267BB84A242B24E81E0C0C8955CFFC061A4CA69@G9W0343.americas.hpqcorp.net>
On Mon, Aug 18, 2014 at 11:27:01PM +0000, Li, Zhen-Hua wrote:
> : [fault reason 01] Present bit in root entry is clear
> It appears when iommu initializing in the kdump kernel.
Hmm, do you have an explanation how this can happen? From how I read the
code, the kdump kernel disables translation on the IOMMU, then sets a
new root entry, and then re-enabled translation. To me it looks like
there is no point in time where translation is enabled and the
root-entry is clear (present-bit==0).
But obviously I am missing something if you see the message above.
Btw, have you looked into this patch-set posted earlier this year:
https://lkml.org/lkml/2014/4/24/836
It approaches the same problem-space, but also cares about in-flight
DMA.
Joerg
next prev parent reply other threads:[~2014-08-19 11:02 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-08-18 8:59 [PATCH 1/1] iommu/vt-d : clear old root entry for dump kernel Li, Zhen-Hua
2014-08-18 23:01 ` Li, Zhen-Hua
2014-08-18 23:23 ` Joerg Roedel
2014-08-18 23:27 ` Li, Zhen-Hua
2014-08-19 11:02 ` Joerg Roedel [this message]
2014-08-20 9:54 ` Li, ZhenHua
2014-08-18 23:47 ` Li, Zhen-Hua
2014-08-18 23:59 ` Li, Zhen-Hua
2014-08-19 5:49 ` Li, ZhenHua
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