linux-kernel - Re: IO_PAGE_FAULTs on unity mapped regions during amd_iommu

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20130205133104.GC2532@8bytes.org>
Date:	Tue, 5 Feb 2013 14:31:05 +0100
From:	Joerg Roedel <joro@...tes.org>
To:	Shuah Khan <shuah.khan@...com>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	stable <stable@...r.kernel.org>,
	iommu@...ts.linux-foundation.org, shuahkhan@...il.com
Subject: Re: IO_PAGE_FAULTs on unity mapped regions during amd_iommu_init()
 in Linux 3.4

Hi Shuah,

On Fri, Feb 01, 2013 at 11:31:59AM -0700, Shuah Khan wrote:
> Yes, 3.7 has the same window of opportunity for this race condition,
> however I couldn't figure out why it doesn't happen on 3.7. On 3.7 the
> window between amd_iommu_init_hardware() and amd_iommu_init_dma_ops()
> might actually be wider than the window in 3.4.

I think this is highly timing related. IOMMU initialization may have
been moved by a few milliseconds between the kernel versions which might
cause the warnings to appear or disappear. I don't think it has much
value to dive deeper into the differences between the initialization
sequences.

As somethimes with such issues there is a simple and a more complex fix
for that. I'll try to come up with a simple fix for the next merge
window and implement the clean and more complex one for the next one.

	Joerg

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/