Messages in this thread | | | Subject | Re: [PATCH 6/7] x86/spec_ctrl: Add sysctl knobs to enable/disable SPEC_CTRL feature | From | Dave Hansen <> | Date | Thu, 4 Jan 2018 10:36:30 -0800 |
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On 01/04/2018 10:33 AM, Borislav Petkov wrote: >> 2. At run time >> echo 0 > /sys/kernel/debug/ibrs_enabled will turn off IBRS >> echo 1 > /sys/kernel/debug/ibrs_enabled will turn on IBRS in kernel >> echo 2 > /sys/kernel/debug/ibrs_enabled will turn on IBRS in both userspace and kernel > I am not sure that tristate is really needed. What's wrong with on/off > only?
Lots of things:
Distros have the tri-state already deployed. Paranoid people want "IBRS always" aka "ibrs 2". Future CPUs may have cheap-enough IBRS to not be worth switching it.
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