From: Malcolm Crossley <malcolm.crossley@citrix.com>
To: Jan Beulich <JBeulich@suse.com>
Cc: Andrew Cooper <Andrew.Cooper3@citrix.com>,
"xiantao.zhang@intel.com" <xiantao.zhang@intel.com>,
xen-devel <xen-devel@lists.xen.org>
Subject: Re: [PATCH] VTD/Intremap: Disable Intremap on Chipset 5500/5520/X58 due to errata
Date: Wed, 16 Jan 2013 14:33:39 +0000 [thread overview]
Message-ID: <50F6BA43.6000100@citrix.com> (raw)
In-Reply-To: <50F6C3E002000078000B649F@nat28.tlf.novell.com>
On 16/01/13 14:14, Jan Beulich wrote:
>>>> On 16.01.13 at 00:27, Malcolm Crossley <malcolm.crossley@citrix.com> wrote:
>> Unfortunately this chipset is very common and many BIOSes are not
>> disabling remapping. We can detect this in Xen and prevent turning on
>> remapping in the first place. However, this will turn VT-d off on many
>> systems by default.
> Why would the IOMMU be turned off in that case as a whole?
> Interrupt remapping is not a prerequisite iirc.
You are correct. I read the description of XSA-3 but didn't the check
the current xen-unstable code correctly.
>> Users who still wish to use VT-d can use iommu=force if they are happy
>> exposing the associated security risk.
> "iommu=force" doesn't enable interrupt remapping if it was
> forcibly turned off.
This was based upon the faulty code reading above and therefore the
comment is wrong . I will change the patch description.
> Jan
>
prev parent reply other threads:[~2013-01-16 14:33 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-15 23:27 [PATCH] VTD/Intremap: Disable Intremap on Chipset 5500/5520/X58 due to errata Malcolm Crossley
2013-01-16 8:00 ` Zhang, Xiantao
2013-01-16 13:57 ` Jan Beulich
2013-01-16 21:09 ` Malcolm Crossley
2013-01-17 8:49 ` Jan Beulich
2013-01-17 9:01 ` Ian Campbell
2013-01-17 9:09 ` Jan Beulich
2013-01-17 9:15 ` Ian Campbell
2013-01-17 9:33 ` Jan Beulich
2013-01-17 9:51 ` Ian Campbell
2013-01-17 10:01 ` Jan Beulich
2013-01-17 10:02 ` Malcolm Crossley
2013-01-17 10:41 ` Jan Beulich
2013-01-16 14:14 ` Jan Beulich
2013-01-16 14:33 ` Malcolm Crossley [this message]
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