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Re: [Qemu-ppc] [PULL 00/60] ppc-for-4.0 queue 20190310
From: |
David Gibson |
Subject: |
Re: [Qemu-ppc] [PULL 00/60] ppc-for-4.0 queue 20190310 |
Date: |
Tue, 12 Mar 2019 21:33:14 +1100 |
User-agent: |
Mutt/1.11.3 (2019-02-01) |
On Tue, Mar 12, 2019 at 10:01:45AM +0000, Peter Maydell wrote:
> On Tue, 12 Mar 2019 at 03:34, David Gibson <address@hidden> 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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- [Qemu-ppc] [PULL 16/60] PPC: E500: Update u-boot to v2019.01, (continued)
- [Qemu-ppc] [PULL 16/60] PPC: E500: Update u-boot to v2019.01, David Gibson, 2019/03/10
- Re: [Qemu-ppc] [PULL 00/60] ppc-for-4.0 queue 20190310, Peter Maydell, 2019/03/10
- Re: [Qemu-ppc] [Qemu-devel] [PULL 00/60] ppc-for-4.0 queue 20190310, Alex Bennée, 2019/03/11
- Re: [Qemu-ppc] [Qemu-devel] [PULL 00/60] ppc-for-4.0 queue 20190310, David Gibson, 2019/03/11
- Re: [Qemu-ppc] [Qemu-devel] [PULL 00/60] ppc-for-4.0 queue 20190310, Alex Bennée, 2019/03/12
- Re: [Qemu-ppc] [Qemu-devel] [PULL 00/60] ppc-for-4.0 queue 20190310, David Gibson, 2019/03/12
- Re: [Qemu-ppc] [Qemu-devel] [PULL 00/60] ppc-for-4.0 queue 20190310, Alex Bennée, 2019/03/13
- Re: [Qemu-ppc] [Qemu-devel] [PULL 00/60] ppc-for-4.0 queue 20190310, David Gibson, 2019/03/13
Re: [Qemu-ppc] [PULL 00/60] ppc-for-4.0 queue 20190310, David Gibson, 2019/03/11