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Re: [Xen-devel] HT Vulnerability CAN-2005-0109

  • To: xen-devel@xxxxxxxxxxxxxxxxxxx
  • From: "Jonathan S. Shapiro" <shap@xxxxxxxxxxx>
  • Date: Wed, 18 May 2005 11:27:00 -0400
  • Delivery-date: Wed, 18 May 2005 15:26:50 +0000
  • Importance: Normal
  • List-id: Xen developer discussion <xen-devel.lists.xensource.com>

> Is it possible that two domain kernels running on the same physical core
but on different ht threads leak information to each other exploiting
this covert/side channels?

It is possible. When exploited, this is a fairly high bandwiidth channel. It is 
possible for the nucleus to prevent this through page coloring. 

All that being said, future processors are moving from HT to multicore. The 
problem then migrates to the L2 cache, where coloring is much less effective. 
It is unlikely that there exists any satisfsactory solution short of flushing 
or disabling the cache, neither of which is pragmatically viable.

Current high assurance requirements don't require that you solve  the channel 
problem. They require that you characterize them and make a reasonable efffort 
to minimize them.


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