On 05/22/2018 08:06 AM, Marc Zyngier wrote: > On a system where the firmware implements ARCH_WORKAROUND_2, > it may be useful to either permanently enable or disable the > workaround for cases where the user decides that they'd rather > not get a trap overhead, and keep the mitigation permanently > on or off instead of switching it on exception entry/exit. > > In any case, default to the mitigation being enabled. > > Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx> > --- > Documentation/admin-guide/kernel-parameters.txt | 17 ++++ > arch/arm64/include/asm/cpufeature.h | 6 ++ > arch/arm64/kernel/cpu_errata.c | 102 ++++++++++++++++++++---- > 3 files changed, 109 insertions(+), 16 deletions(-) > > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > index f2040d46f095..646e112c6f63 100644 > --- a/Documentation/admin-guide/kernel-parameters.txt > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -4092,6 +4092,23 @@ > expediting. Set to zero to disable automatic > expediting. > > + ssbd= [ARM64,HW] > + Speculative Store Bypass Disable control > + > + On CPUs that are vulnerable to the Speculative > + Store Bypass vulnerability and offer a > + firmware based mitigation, this parameter > + indicates how the mitigation should be used: > + > + force-on: Unconditionnaly enable mitigation for Unconditionally > + for both kernel and userspace > + force-off: Unconditionnaly disable mitigation for Unconditionally > + for both kernel and userspace > + kernel: Always enable mitigation in the > + kernel, and offer a prctl interface > + to allow userspace to register its > + interest in being mitigated too. > + > stack_guard_gap= [MM] > override the default stack gap protection. The value > is in page units and it defines how many pages prior -- ~Randy _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
