On Wed, Oct 02, 2024 at 04:55:25PM +0100, Marc Zyngier wrote: > Marc Zyngier <maz@xxxxxxxxxx> wrote: > > > + if (!kvm_has_gcs(kvm)) > > > + kvm->arch.fgu[HFGxTR_GROUP] |= (HFGxTR_EL2_nGCS_EL0 | > > > + HFGxTR_EL2_nGCS_EL1); > > Why are you still allowing the GCS instructions when GCS isn't > > enabled? > Scratch that, they are NOPs when GCS isn't enabled, so there shouldn't > be any need for extra traps. They are, though really they should UNDEF if GCS isn't there (which I had thought was what you were referencing here). Equally we only have traps for a subset of GCS instructions and it's not like there aren't a whole bunch of untrappable extensions anyway so it's not clear it's worth the effort just for that.
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