From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andrew Cooper <andrew.cooper3@citrix.com>
Subject: Re: [PATCH RFC] VT-d: honor firmware-first mode in
 XSA-59 workaround code
Date: Thu, 22 May 2014 15:19:25 +0100
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To: Jan Beulich <JBeulich@suse.com>
Cc: Yang Z Zhang <yang.z.zhang@intel.com>, xen-devel <xen-devel@lists.xenproject.org>, Malcolm Crossley <malcolm.crossley@citrix.com>, Kevin Tian <kevin.tian@intel.com>, Donald D Dugger <donald.d.dugger@intel.com>
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On 22/05/14 11:33, Jan Beulich wrote:
>>>> On 22.05.14 at 12:19, <andrew.cooper3@citrix.com> wrote:
>> No.  We have not observed an issue from XSA-59.
>>
>> The version of XenServer we had the issue with didn't contain any of the
>> XSA-59 fixes at the point that the problem was observed.
> Then what was yesterday's alert about then? I.e. do we have any
> indication that the workaround as is may cause problems, and that
> hence the (relatively involved) patch here is needed at all? And, how
> are you intending to test this patch if you haven't even seen an
> issue?
>
> Jan
>

As part of finding the root cause of our issue, we identified that just
as Dom0 must not play with AER in firmware first mode, Xen must not play
either.

I believe that we have XSA-59 affected hardware with both firmware-first
and non-firmware-first HEST tables, so we should be able to
behaviourally test the patch.

~Andrew