Re: [Xen-devel] [PATCH 3/3 V3] XSA-60 security hole: cr0.cd handling

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 22/10/13 16:26, Tim Deegan wrote:
> At 15:55 +0000 on 21 Oct (1382367312), Liu, Jinsong wrote:
>> From 4ff1e2955f67954e60562b29a00adea89e5b93ae Mon Sep 17 00:00:00 2001
>> From: Liu Jinsong <jinsong.liu@xxxxxxxxx>
>> Date: Thu, 17 Oct 2013 05:49:23 +0800
>> Subject: [PATCH 3/3 V3] XSA-60 security hole: cr0.cd handling
>>
>> This patch solves XSA-60 security hole:
>> 1. For guest w/o VT-d, and for guest with VT-d but snooped, Xen need
>> do nothing, since hardware snoop mechanism has ensured cache coherency.
>>
>> 2. For guest with VT-d but non-snooped, cache coherency can not be
>> guaranteed by h/w snoop, therefore it need emulate UC type to guest:
>> 2.1). if it works w/ Intel EPT, set guest IA32_PAT fields as UC so that
>> guest memory type are all UC.
>> 2.2). if it works w/ shadow, drop all shadows so that any new ones would
>> be created on demand w/ UC.
>>
>> This patch also fix a bug of shadow cr0.cd setting. Current shadow has a
>> small window between cache flush and TLB invalidation, resulting in possilbe
>> cache pollution. This patch pause vcpus so that no vcpus context involved
>> into the window. 
>>
>> Signed-off-by: Liu Jinsong <jinsong.liu@xxxxxxxxx>
> Reviewed-by: Tim Deegan <tim@xxxxxxx>

Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

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