Messages in this thread | | | Date | Mon, 19 Nov 2018 14:32:48 +0100 (CET) | From | Thomas Gleixner <> | Subject | Re: [Patch v5 11/16] x86/speculation: Add Spectre v2 app to app protection modes |
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Tim,
On Fri, 16 Nov 2018, Tim Chen wrote:
> Add new protection modes for Spectre v2 mitigations against > Spectre v2 attacks on user processes. There are three modes: > > strict mode: > In this mode, IBPB and STIBP are deployed full > time to protect all processes. > > lite mode: > In this mode, IBPB and STIBP are only deployed on > processes marked with TIF_STIBP flag. > > none mode: > In this mode, no mitigations are deployed. > > The protection mode can be specified by the spectre_v2_app2app > boot parameter with the following semantics: > > spectre_v2_app2app= > off - Turn off mitigation > lite - Protect processes which are marked non-dumpable > strict - Protect all processes > auto - Kernel selects the mode
Is there any reason why we need yet another naming convention?
pti= on, off, auto
spectre_v2= on, off, auto
spec_store_bypass_disable = on, off, auto, prctl, seccomp
> Not specifying this option is equivalent to > spectre_v2_app2app=auto.
For better understanding it's nowhere documented what auto does.
> + spectre_v2_app2app= > + [X86] Control mitigation of Spectre variant 2 > + application to application (indirect branch speculation) > + vulnerability. > + > + off - Unconditionally disable mitigations > + lite - Protect tasks which have requested restricted > + indirect branch speculation via the > + PR_SET_SPECULATION_CTRL prctl(). > + strict - Protect all processes > + auto - Kernel selects the mode > + > + Not specifying this option is equivalent to > + spectre_v2_app2app=auto. > + > + Setting spectre_v2=off will also turn off this mitigation. > + > + Setting spectre_v2=on implies unconditionally enabling > + this mitigation.
Can we please have a full documentation for all the spectre_v2 stuff similar to l1tf?
Thanks,
tglx
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