On Tue, Mar 12, 2019 at 10:01:45AM +0000, Peter Maydell wrote: > On Tue, 12 Mar 2019 at 03:34, David Gibson <da...@gibson.dropbear.id.au> > wrote: > > Ok, done. As a rule these warnings are there intentionally for TCG - > > we want to enable Spectre/Meltdown mitigations by default, but no-one > > really knows if and how to implement them for TCG. > > For the Arm "block speculation" type instructions what we did was > say "TCG's execution doesn't speculate in a relevant way, and > we treat the TCG backends as not a security boundary anyway, > so we'll end the TB and put in a memory barrier and call that > sufficient". That is, they're provided for the benefit of > emulating guest OSes that use them, rather than because they > make a difference from a security perspective. > > I don't know exactly what the semantics of the PPC mitigations > are, but we should probably think about and document a coherent > position on this for TCG.
Yes, but this requires input from someone who understands both Spectre
and TCG well enough, which I am not.
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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